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Benchmark run run-20260924-codex-prescriptive

Benchmark run run-20260924-codex-prescriptive

This page contains exactly the publishable benchmark observations recorded in run run-20260924-codex-prescriptive; it does not select or aggregate them. Return to the run index or view aggregate metrics.

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Rows are pre-aggregated by task, target, prompt variant, MCP-instruction mode, context, arm, and restriction. Numeric values show median (p50), IQR, p90, maximum, and sample count. Boolean checks show pass counts and success rates. Filters apply to these summary groups; per-run observations remain available on their run pages.

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Baseline vs semedit

Comparison evaluates baseline and semedit values within each restriction policy, target, and context group. Negative changes mark improvements for these lower-is-better metrics; positive changes mark degradations.

Detailed observations

Empirical telemetry measuring wall-clock latency, token usage, tool turns, and compiler correctness when AI coding agents perform code modifications.

Every benchmark pairs Vanilla LLM (standard file editing tools) against Semedit MCP (deterministic AST compiler operations).

Benchmark Methodology & Transparency

  • Reproducibility & Provenance: Self-contained txtar archives define test scenarios. Links below resolve to commit-anchored GitHub source files for published commits, or cryptographic SHA-256 fingerprints for uncommitted local fixtures.
  • Model Cost: Tables report model-specific credit consumption where a target model has a declared schedule: (uncached input × input credits + cached input × cached credits + (reasoning + visible output) × output credits) / 1,000,000. Thinking tokens use the output rate. ADR-0043 defines the per-million-token credit rates.
  • Multi-Level Correctness Oracle: Four validation levels evaluate each trial:
    1. Level 1 (Mutation Policy): Restricts file modifications strictly to authorized paths.
    2. Level 2 (AST Invariants): Compiler AST verification of required symbols, imports, and relative declaration ordering.
    3. Level 3 (Clean Build): Strict compilation validation with zero compiler or typecheck errors.
    4. Level 4 (Test Suite): Unit and integration test suite execution.
  • Isolated Sandboxing: Each trial executes in an ephemeral directory with pristine git and module state.

Test case: task-04-insert-public

Target: codex/gpt-5.6-luna/high

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-04-insert-public
Targetcodex/gpt-5.6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_04_insert_public.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package api

type Server struct {
	Port int
}

func (s *Server) Start() {}

func (s *Server) internalRun() {}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency35.83s50.33s+40.5%54.26s52.46s-3.3%
Process Start → First Event0.58s0.12s—0.12s0.12s—
First Event → First Tool Call8.70s7.24s—8.20s10.48s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles56+20.0%660%
Initial Load / Discovery Turns52-60.0%62-66.7%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)56+20.0%660%
Output Tokens11451683+47.0%18491943+5.1%
Reasoning / Thinking Tokens347738+112.7%803861+7.2%
Total Input Tokens102686208466+103.0%168967230867+36.6%
Cached Input Tokens84736177152+109.1%141568200704+41.8%
Uncached Input Tokens1795031314+74.5%2739930163+10.1%
Cost0.17690.3178+79.7%0.28730.3353+16.7%
Cached vs Uncached Token Ratio4.72:15.66:1+19.8%5.17:16.65:1+28.8%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g '*.go' -g 'Makefile' -g 'go.mod' -g 'go.sum' | sort && \
rg -n \"type Server|func .*Server|private|helpers\" -g '*.go' ."
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g '*.go' -g 'Makefile' -g 'README*' | sed -n '1,120p' && \
printf '\\n--- status ---\\n' && \
git status --short"
2✓ ✓
/bin/zsh -lc "sed -n '1,160p' api/server.go"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go && \
printf '\\n--- tests ---\\n' && \
sed -n '1,240p' api/server_test.go && \
printf '\\n--- top-level files ---\\n' && \
rg --files -g '"'!api/server.go'"' -g '"'!api/server_test.go'"' | sed -n '1,120p'"
3✓ ✓
/bin/zsh -lc "sed -n '1,160p' Makefile 2>/dev/null || \
true; sed -n '1,120p' go.mod; sed -n '1,120p' go.sum 2>/dev/null || \
true"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "api/server.go",
  "placement": "before_symbol",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}",
  "target_symbol": "internalRun"
}
4✓ ✓
/bin/zsh -lc "sed -n '1,160p' api/server_test.go && \
git status --short"
✓ ✓
/bin/zsh -lc "git diff -- api/server.go && \
printf '\\n--- file ---\\n' && \
sed -n '1,120p' api/server.go && \
printf '\\n--- test ---\\n' && \
go test ./..."
5✓ ✓
/bin/zsh -lc 'gofmt -w api/server.go && \
go test ./... && \
git diff --check && \
git status --short -- api/server.go api/server_test.go go.mod go.sum && \
git diff -- api/server.go'
✓ ✓
/bin/zsh -lc "git status --short -- api/server.go api/server_test.go go.mod go.sum && \
printf '\\n--- HEAD server ---\\n' && \
git show HEAD:api/server.go && \
printf '\\n--- protected hashes ---\\n' && \
shasum go.mod go.sum 2>/dev/null || \
true"
6—✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
git status --short --untracked-files=all | sed -n '1,80p' && \
git ls-files --stage | sed -n '1,40p' && \
printf '\\n--- ignore ---\\n' && \
git check-ignore -v api/server.go api/server_test.go go.mod || \
true"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*_test.go'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort | sed -n '1,120p' && \
printf '\\n--- status ---\\n' && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g '*.go' -g 'Makefile' -g 'README*' | sort; printf '\\n--- brief ---\\n'; if [ -f PROJECT_BRIEF.md ]; then sed -n '1,220p' PROJECT_BRIEF.md; fi; printf '\\n--- git status ---\\n'; git status --short"
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go && \
printf '\\n--- router ---\\n' && \
sed -n '1,220p' api/router.go && \
printf '\\n--- project docs ---\\n' && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g 'Makefile' -g 'AGENTS*.md' | sort"
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- api/server.go ---'; nl -ba api/server.go; printf '%s\\n' '--- api/router.go ---'; nl -ba api/router.go; printf '%s\\n' '--- Makefile ---'; if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi; printf '%s\\n' '--- go files ---'; for f in api/*.go auth/*.go cache/*.go config/*.go db/*.go health/*.go logging/*.go metrics/*.go models/*.go utils/*.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,180p' \""'$f"; done'
3✓ ✓
/bin/zsh -lc "rg -n \"Server|InitServer|internalRun|Start\" . -g '*.go' -g '"'!go.mod'"' -g '"'!go.sum'"'"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": false,
  "file": "api/server.go",
  "placement": "public_end",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}"
}
4✓ ✓
/bin/zsh -lc "sed -n '1,160p' api/server_test.go && \
sed -n '1,160p' AGENTS.override.md"
? ✗
/bin/zsh -lc 'make check'
5✓ ✓
/bin/zsh -lc 'git diff -- api/server.go && \
git status --short -- api/server.go api/server_test.go go.mod go.sum && \
if [ -f Makefile ]; then make check; else go test ./...; fi'
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- diff ---'; git diff -- api/server.go; printf '%s\\n' '--- changed files in fixture ---'; git status --short -- api/server.go api/server_test.go go.mod go.sum; printf '%s\\n' '--- go test ---'; go test ./..."
6✓ ✓
/bin/zsh -lc "sed -n '1,80p' api/server.go && \
gofmt -d api/server.go && \
git rev-parse --show-toplevel && \
git status --short --untracked-files=all -- api/server.go api/server_test.go go.mod go.sum"
✓ ✓
/bin/zsh -lc 'nl -ba api/server.go; git status --short --untracked-files=all; git diff --no-ext-diff -- api/server.go; git show HEAD:api/server.go | nl -ba'

Target: codex/gpt-5.6-luna/medium

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-04-insert-public
Targetcodex/gpt-5.6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_04_insert_public.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package api

type Server struct {
	Port int
}

func (s *Server) Start() {}

func (s *Server) internalRun() {}
MetricVanilla (Small)⚠ MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency36.29s42.72sN/A43.42s58.98s+35.8%
Process Start → First Event0.12s0.14s—0.12s0.13s—
First Event → First Tool Call6.69s6.47s—7.81s7.11s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns11N/A110%
Internal Tool Cycles56N/A58+60.0%
Initial Load / Discovery Turns52N/A52-60.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)56N/A58+60.0%
Output Tokens11811318N/A12811702+32.9%
Reasoning / Thinking Tokens321362N/A328542+65.2%
Total Input Tokens144212165208N/A145710255380+75.3%
Cached Input Tokens129280145408N/A112896198144+75.5%
Uncached Input Tokens1493219800N/A3281457236+74.4%
Cost0.18440.2221N/A0.26880.4526+68.4%
Cached vs Uncached Token Ratio8.66:17.34:1N/A3.44:13.46:1+0.6%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/AFAIL—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*test*'"' -g 'AGENTS*' -g 'PROJECT_BRIEF.md' | head -80 && \
rg -n \"type Server|func Init|private|func [a-z]\" -g '*.go' ."
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*_test.go'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort && \
rg -n \"type Server|func .*Server|private|helper\" -g '*.go' -g '"'!**/*_test.go'"' ."
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go && \
printf '\\n--- files ---\\n' && \
rg --files -g '"'!AGENTS.override.md'"' | sort && \
printf '\\n--- git status ---\\n' && \
git status --short"
✓ ✓
/bin/zsh -lc "sed -n '1,120p' api/server.go && \
git status --short"
3✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server_test.go && \
printf '\\n--- go.mod ---\\n' && \
sed -n '1,120p' go.mod && \
printf '\\n--- override ---\\n' && \
sed -n '1,260p' AGENTS.override.md"
✓ ✓
/bin/zsh -lc "rg -n \"semantic_insert_function|insert_function|semedit\" README.md docs api .codex 2>/dev/null | head -80; rg --files -g '*semedit*' -g '*.sh' -g 'Makefile' | sort | head -80"
4✓ ✓
/bin/zsh -lc 'gofmt -w api/server.go && \
go test ./... && \
git diff -- api/server.go go.mod go.sum'
✓ ✓
/bin/zsh -lc "gofmt -w api/server.go && \
git diff -- api/server.go && \
git diff --name-only -- api/server.go go.mod go.sum '*_test.go'"
5✓ ✓
/bin/zsh -lc "sed -n '1,80p' api/server.go && \
git status --short -- api/server.go go.mod go.sum && \
git diff --no-ext-diff -- api/server.go"
✓ ✓
/bin/zsh -lc "sed -n '1,40p' api/server.go; git status --short -- api/server.go go.mod go.sum; git ls-files --stage -- api/server.go"
6—✓ ✓
/bin/zsh -lc "rg --files -g 'go.mod' -g 'go.sum' -g 'Makefile' -g '*_test.go' | sort; go test ./..."
⚠ Why no semantic edit tool was used
I did not discover any callable `semantic_*` tools from the available semedit MCP server in this fixture. I judged the direct one-function edit sufficient for this small task.
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g '*.go' -g 'Makefile' | sort && \
rg -n \"type Server|func .*Server|private helpers|func [a-z]\" -g '*.go' ."
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g '*.go' -g 'Makefile' -g 'README*' | head -80"
2✓ ✓
/bin/zsh -lc "sed -n '1,160p' api/server.go && \
printf '\\n--- router ---\\n' && \
sed -n '1,160p' api/router.go && \
printf '\\n--- brief/make ---\\n' && \
if test -f PROJECT_BRIEF.md; then sed -n '1,220p' PROJECT_BRIEF.md; fi; if test -f Makefile; then sed -n '1,220p' Makefile; fi && \
printf '\\n--- status ---\\n' && \
git status --short"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go && \
printf '\\n--- router.go ---\\n' && \
sed -n '1,200p' api/router.go && \
printf '\\n--- root files ---\\n' && \
rg --files -g '"'!*.go'"' | sort"
3✓ ✓
/bin/zsh -lc "sed -n '1,160p' api/server_test.go && \
sed -n '1,120p' api/router_test.go && \
find . -maxdepth 2 -type f -not -path './.git/*' -print | sort"
✓ ✓
/bin/zsh -lc "command -v semedit || \
true; command -v semantic-editor || \
true; find . -maxdepth 3 -type f -not -path './.git/*' -print | sort; printf '\\n--- go.mod ---\\n'; sed -n '1,120p' go.mod"
4✓ ✓
/bin/zsh -lc 'gofmt -w api/server.go && \
git diff -- api/server.go && \
git status --short -- api/server.go api/server_test.go go.mod go.sum && \
go test ./...'
✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server_test.go && \
sed -n '1,220p' api/router_test.go && \
for f in auth/auth.go cache/cache.go config/config.go db/db.go health/health.go logging/logging.go metrics/metrics.go models/models.go utils/utils.go; do echo \"--- "'$f"; sed -n '"'1,100p' \""'$f"; done'
5✓ ✓
/bin/zsh -lc "sed -n '1,80p' api/server.go && \
git ls-files --stage -- api/server.go api/server_test.go go.mod go.sum && \
git status --short --untracked-files=all -- api/server.go api/server_test.go go.mod go.sum"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": false,
  "file": "api/server.go",
  "placement": "public_end",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}"
}
6—✓ ✓
/bin/zsh -lc 'git diff -- api/server.go && \
git status --short && \
if [ -f Makefile ]; then make check; else go test ./...; fi'
7—✓ ✓
/bin/zsh -lc "sed -n '1,120p' api/server.go; git rev-parse --show-toplevel; git status --short -- api/server.go go.mod go.sum api/server_test.go; git diff --no-ext-diff -- api/server.go"
8—✓ ✓
/bin/zsh -lc 'git check-ignore -v api/server.go || \
true; git ls-files --stage -- api/server.go; git diff --no-index /dev/null api/server.go || \
true; git status --short --untracked-files=all | head -20'

Target: codex/gpt-6-luna/high

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-04-insert-public
Targetcodex/gpt-6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_04_insert_public.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package api

type Server struct {
	Port int
}

func (s *Server) Start() {}

func (s *Server) internalRun() {}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency36.10s21.12s-41.5%23.70s26.73s+12.8%
Process Start → First Event0.12s0.12s—0.13s0.13s—
First Event → First Tool Call7.76s4.38s—5.42s7.44s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles53-40.0%440%
Initial Load / Discovery Turns220%42-50.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)53-40.0%440%
Output Tokens1416441-68.9%741755+1.9%
Reasoning / Thinking Tokens363184-49.3%370315-14.9%
Total Input Tokens120294104969-12.7%115345114387-0.8%
Cached Input Tokens10803291904-14.9%103936100096-3.7%
Uncached Input Tokens1226213065+6.5%1140914291+25.3%
Cost0.07990.0635-20.6%0.06840.0741+8.4%
Cached vs Uncached Token Ratio8.81:17.03:1-20.2%9.11:17.00:1-23.1%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc 'rg -n "type Server|func .*Server|''^func [a-z]" . --glob '"'*.go'"
✓ ✓
/bin/zsh -lc "rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g '*.go' -g 'go.mod' -g 'go.sum'"
2✓ ✓
/bin/zsh -lc 'cat api/server.go && \
git status --short'
✓ ✓
/bin/zsh -lc 'cat api/server.go'
3? ✗
/bin/zsh -lc "python3 -c 'from pathlib import Path; import os, tempfile, time; p=Path(\"api/server.go\"); data=p.read_text(); old=\"func (s *Server) Start() {}\\n\\nfunc (s *Server) internalRun() {}\\n\"; new=\"func (s *Server) Start() {}\\n\\nfunc InitServer() *Server {\\n\\treturn &Server{}\\n}\\n\\nfunc (s *Server) internalRun() {}\\n\"; assert old in data; st=p.stat(); fd, name=tempfile.mkstemp(dir=p.parent, prefix=\".server.go.\");\\ntry:\\n f=os.fdopen(fd,\"w\"); f.write(data.replace(old,new)); f.flush(); os.fsync(f.fileno()); f.close(); os.replace(name,p); os.utime(p, ns=(st.st_atime_ns, max(time.time_ns(), st.st_mtime_ns+1)));\\n d=os.open(p.parent,os.O_RDONLY); os.fsync(d); os.close(d)\\nexcept BaseException:\\n try: os.unlink(name)\\n except FileNotFoundError: pass\\n raise' && \
git diff -- api/server.go"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "api/server.go",
  "placement": "before_symbol",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}",
  "target_symbol": "internalRun"
}
4✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile
import time

path = Path(\"api/server.go\")
data = path.read_text()
old = \"func (s *Server) Start() {}\\n\\nfunc (s *Server) internalRun() {}\\n\"
new = \"func (s *Server) Start() {}\\n\\nfunc InitServer() *Server {\\n\\treturn &Server{}\\n}\\n\\nfunc (s *Server) internalRun() {}\\n\"
assert old in data
stat = path.stat()
fd, temp_name = tempfile.mkstemp(dir=path.parent, prefix=\".server.go.\")
try:
    with os.fdopen(fd, \"w\") as stream:
        stream.write(data.replace(old, new))
        stream.flush()
        os.fsync(stream.fileno())
    os.replace(temp_name, path)
    os.utime(path, ns=(stat.st_atime_ns, max(time.time_ns(), stat.st_mtime_ns + 1)))
    directory_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(directory_fd)
    finally:
        os.close(directory_fd)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY
git diff -- api/server.go"
—
5? ✗
/bin/zsh -lc 'cat api/server.go && \
git status --short -- api/server.go && \
git diff --no-index /dev/null api/server.go'
—
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "rg --files -g '"'!*test*'"' -g '*.go' -g 'AGENTS.md' -g 'PROJECT_BRIEF.md'"
✓ ✓
/bin/zsh -lc 'rg -n "type Server|func .*Server|''^func " .'
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go && \
sed -n '1,180p' api/router.go"
✓ ✓
/bin/zsh -lc 'cat api/server.go && \
cat api/server_test.go'
3✓ ✓
/bin/zsh -lc 'git diff -- api/server.go go.mod go.sum'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "api/server.go",
  "placement": "public_end",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}"
}
4✓ ✓
/bin/zsh -lc "sed -n '1,80p' api/server.go && \
git status --short"
✓ ✓
/bin/zsh -lc 'cat api/server.go && \
git diff -- api/server.go'

Target: codex/gpt-6-luna/medium

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-04-insert-public
Targetcodex/gpt-6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_04_insert_public.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package api

type Server struct {
	Port int
}

func (s *Server) Start() {}

func (s *Server) internalRun() {}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency17.50s46.79s+167.4%14.62s19.52s+33.6%
Process Start → First Event0.55s0.14s—0.12s0.12s—
First Event → First Tool Call5.30s16.13s—4.26s4.47s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles43-25.0%34+33.3%
Initial Load / Discovery Turns32-33.3%32-33.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)43-25.0%34+33.3%
Output Tokens469326-30.5%282378+34.0%
Reasoning / Thinking Tokens061—073—
Total Input Tokens94873108542+14.4%94521109007+15.3%
Cached Input Tokens8473691904+8.5%8473691904+8.5%
Uncached Input Tokens1013716638+64.1%978517103+74.8%
Cost0.05240.0694+32.5%0.04920.0714+45.1%
Cached vs Uncached Token Ratio8.36:15.52:1-33.9%8.66:15.37:1-37.9%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g '*.go' -g 'go.mod' -g 'go.sum'"
✓ ✓
/bin/zsh -lc "rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g '*.go' -g 'go.mod' -g 'go.sum'"
2✓ ✓
/bin/zsh -lc 'cat api/server.go'
? ✗
/bin/zsh -lc "cat api/server.go && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md'"
3✓ ✓
/bin/zsh -lc ''
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "api/server.go",
  "placement": "public_end",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}"
}
4✓ ✓
/bin/zsh -lc "python3 -c 'from pathlib import Path; p=Path(\"api/server.go\"); s=p.read_text(); marker=\"func (s *Server) Start() {}\"; insert=\"func InitServer() *Server {\\n\\treturn &Server{}\\n}\\n\\n\"; assert marker in s and \"func InitServer()\" not in s; p.write_text(s.replace(marker, insert+marker, 1))'"
—
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "rg --files -g 'AGENTS.md' -g '*.go' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'go.sum'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g '*.go' -g 'Makefile' | head -80"
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' api/server.go"
3✓ ✓
/bin/zsh -lc "rg -n '"'^func .*'"' --glob '*.go'"
? ✗
/bin/zsh -lc 'rg -n "semantic_insert_function|semantic_scaffold|semantic_" .'
4—semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "api/server.go",
  "placement": "public_start",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}"
}

Target: codex/gpt-6-luna/xhigh

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-04-insert-public
Targetcodex/gpt-6-luna/xhigh
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_04_insert_public.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Add public constructor func InitServer() *Server placed before private helpers. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package api

type Server struct {
	Port int
}

func (s *Server) Start() {}

func (s *Server) internalRun() {}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency57.21s43.03s-24.8%34.34s112.30s+227.1%
Process Start → First Event0.12s0.13s—0.51s0.12s—
First Event → First Tool Call12.30s11.01s—8.76s31.25s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles35+66.7%550%
Initial Load / Discovery Turns220%52-60.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)35+66.7%550%
Output Tokens17751558-12.2%11381207+6.1%
Reasoning / Thinking Tokens10861087+0.1%777789+1.5%
Total Input Tokens78684160544+104.0%137305159036+15.8%
Cached Input Tokens67584142592+111.0%125184142592+13.9%
Uncached Input Tokens1110017952+61.7%1212116444+35.7%
Cost0.08040.1136+41.3%0.08550.1017+18.9%
Cached vs Uncached Token Ratio6.09:17.94:1+30.5%10.33:18.67:1-16.0%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "rg --files -g '*.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g '"'!vendor'"'"
✓ ✓
/bin/zsh -lc "rg --files -g '"'!vendor'"' | head -80"
2✓ ✓
/bin/zsh -lc "git status --short && \
sed -n '1,240p' api/server.go"
✓ ✓
/bin/zsh -lc 'cat api/server.go'
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import tempfile
import time
from pathlib import Path

path = Path('api/server.go')
content = path.read_text()
old = 'func (s *Server) Start() {}\\n\\nfunc (s *Server) internalRun() {}\\n'
new = 'func (s *Server) Start() {}\\n\\nfunc InitServer() *Server {\\n\\treturn &Server{}\\n}\\n\\nfunc (s *Server) internalRun() {}\\n'
if content.count(old) "'!= 1:
    raise SystemExit('"'expected insertion point exactly once in api/server.go')
updated = content.replace(old, new, 1)
stat = path.stat()
mtime_ns = max(time.time_ns(), stat.st_mtime_ns + 1_000_000)
fd, temp_name = tempfile.mkstemp(prefix='.server.go.', dir=path.parent)
try:
    with os.fdopen(fd, 'w') as temp_file:
        temp_file.write(updated)
        temp_file.flush()
        os.fchmod(temp_file.fileno(), stat.st_mode)
        os.utime(temp_name, ns=(stat.st_atime_ns, mtime_ns))
        os.fsync(temp_file.fileno())
    os.replace(temp_name, path)
    dir_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(dir_fd)
    finally:
        os.close(dir_fd)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY
cat api/server.go"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "api/server.go",
  "placement": "before_symbol",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}",
  "target_symbol": "internalRun"
}
4—✓ ✓
/bin/zsh -lc 'git diff -- api/server.go api/server_test.go go.mod go.sum && \
git status --short'
5—✓ ✓
/bin/zsh -lc 'cat api/server.go && \
git rev-parse --show-toplevel && \
git check-ignore -v api/server.go'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File api/server.go modified (9 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc 'rg -n "type Server|func [A-Z]|func [a-z]" .'
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g '*.go' -g 'AGENTS.md' | head -100 && \
rg -n 'type Server|func .*Server|private helper|func [a-z]' --glob '*.go' ."
2✓ ✓
/bin/zsh -lc "cat api/server.go && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g 'AGENTS.md' -g 'AGENTS.override.md' ."
✓ ✓
/bin/zsh -lc 'cat api/server.go && \
cat go.mod'
3✓ ✓
/bin/zsh -lc 'git diff -- api/server.go go.mod go.sum api/server_test.go'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": true,
  "file": "api/server.go",
  "placement": "before_symbol",
  "source": "func InitServer() *Server {\n\treturn \u0026Server{}\n}",
  "target_symbol": "internalRun"
}
4✓ ✓
/bin/zsh -lc 'cat api/server.go'
✓ ✓
/bin/zsh -lc 'git diff -- api/server.go && \
git status --short'
5✓ ✓
/bin/zsh -lc 'git status --short'
✓ ✓
/bin/zsh -lc 'cat api/server.go'

Test case: task-07-generate-template-main

Target: codex/gpt-5.6-luna/high

crypto_rand prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-5.6-luna/high
Prompt variantcrypto_rand
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)⚠ MCP (Large)Δ (Large)
Wall-Clock Latency53.97s112.86s+109.1%65.61s51.13sN/A
Process Start → First Event0.12s0.14s—0.54s0.12s—
First Event → First Tool Call13.47s6.58s—8.00s8.89s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%11N/A
Internal Tool Cycles512+140.0%85N/A
Initial Load / Discovery Turns52-60.0%81N/A
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)512+140.0%85N/A
Output Tokens18024077+126.2%24351986N/A
Reasoning / Thinking Tokens9172147+134.1%1213882N/A
Total Input Tokens142497460606+223.2%169096147319N/A
Cached Input Tokens124160423936+241.4%138240113920N/A
Uncached Input Tokens1833736670+100.0%3085633399N/A
Cost0.23530.5820+147.3%0.33280.3100N/A
Cached vs Uncached Token Ratio6.77:111.56:1+70.7%4.48:13.41:1N/A
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/AFAIL—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 20 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS*' -g 'PROJECT_BRIEF.md' -g 'Makefile' -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'README*' | sort && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,200p' main.go && \
printf '\\n--- Makefile (if present) ---\\n' && \
if [ -f Makefile ]; then sed -n '1,200p' Makefile; fi"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!AGENTS.override.md'"' -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'README*' -g 'docs/**' | sort"
2✓ ✓
/bin/zsh -lc 'gofmt -w main.go'
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
git status --short"
3✓ ✓
/bin/zsh -lc 'go run .'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "greeting := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nrandomNumber, err := rand.Int(rand.Reader, big.NewInt(100))\nif err != nil {\n\tpanic(fmt.Errorf(\"generate random number: %w\", err))\n}\nif err := greeting.Execute(os.Stdout, randomNumber); err != nil {\n\tpanic(fmt.Errorf(\"execute greeting template: %w\", err))\n}",
  "file": "main.go",
  "symbol": "main"
}
4✓ ✓
/bin/zsh -lc 'git diff --check'
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
go run ."
5✓ ✓
/bin/zsh -lc 'git status --short && \
git diff -- main.go go.mod go.sum'
✓ ✓
/bin/zsh -lc "if [ -d docs ]; then echo docs-present; else echo docs-absent; fi; if [ -f docs/SUBOPTIMAL_TOOLS.md ]; then sed -n '1,120p' docs/SUBOPTIMAL_TOOLS.md; fi"
6—✓ ✓
/bin/zsh -lc 'mkdir -p docs'
7—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
8—? ✗
/bin/zsh -lc 'make check'
9—✓ ✓
/bin/zsh -lc 'gofmt -d main.go && \
go test ./...'
10—✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
git status --short -- main.go docs/SUBOPTIMAL_TOOLS.md go.mod go.sum && \
go run ."
11—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "crypto/rand",
    "fmt",
    "math/big",
    "os",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "fmt",
    "math/big",
    "os",
    "text/template"
  ]
}
12—✓ ✓
/bin/zsh -lc "sed -n '1,80p' main.go && \
gofmt -d main.go && \
go test ./... && \
go run . && \
git status --short -- main.go docs/SUBOPTIMAL_TOOLS.md go.mod go.sum"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!AGENTS.override.md'"' | sort && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,240p' main.go && \
printf '\\n--- project docs ---\\n' && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!AGENTS.override.md'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,200p' main.go && \
printf '\\n--- project docs ---\\n' && \
for f in PROJECT_BRIEF.md Makefile; do if [ -f \""'$f" ]; then echo "### $f"; sed -n '"'1,220p' \""'$f"; fi; done'
2✓ ✓
/bin/zsh -lc "sed -n '1,160p' go.mod && \
printf '\\n--- nearby main package conventions ---\\n' && \
sed -n '1,160p' api/router.go && \
sed -n '1,120p' config/config.go"
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- repository metadata ---' && \
rg --files .agents .codex 2>/dev/null | sort && \
printf '%s\\n' '--- references to semantic operations ---' && \
rg -n \"semantic_|semedit|make check|go test|go run\" . --glob '"'!go.mod'"' --glob '"'!go.sum'"' --glob '"'!AGENTS.override.md'"' || \
true && \
printf '%s\\n' '--- git status ---' && \
git status --short"
3? ✗
/bin/zsh -lc 'gofmt -w main.go && \
make check'
✓ ✓
/bin/zsh -lc "command -v semedit || \
true; command -v go || \
true; go version; find . -maxdepth 2 -type f -not -path './.git/*' -print | sort"
4✓ ✓
/bin/zsh -lc 'git status --short -- go.mod go.sum main.go'
✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
git diff --check -- main.go && \
go test ./... && \
output=$(go run .) && \
printf '"'program output: %s\\n' \""'$output" && \
git status --short -- main.go go.mod go.sum && \
git diff -- main.go'
5✓ ✓
/bin/zsh -lc 'go run .'
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
git status --short --untracked-files=all -- main.go go.mod go.sum && \
git diff --no-ext-diff -- main.go && \
git ls-files --stage -- main.go go.mod go.sum"
6✓ ✓
/bin/zsh -lc 'git diff --check && \
go test ./...'
—
7✓ ✓
/bin/zsh -lc "git diff -- main.go && \
printf '\\n--- status ---\\n' && \
git status --short"
—
8✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
printf '\\n--- protected files status ---\\n' && \
git status --short -- go.mod go.sum main.go && \
printf '\\n--- repository tracking ---\\n' && \
git ls-files --error-unmatch main.go 2>&1 || \
true"
—
⚠ Why no semantic edit tool was used
I did not discover an available `semantic_*` MCP tool in the fixture environment. Ordinary editing was therefore the only practical option.

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-5.6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency31.14s80.05s+157.1%30.20s100.13s+231.6%
Process Start → First Event0.13s0.13s—0.42s0.12s—
First Event → First Tool Call7.13s8.30s—6.81s6.43s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles39+200.0%313+333.3%
Initial Load / Discovery Turns31-66.7%32-33.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)39+200.0%313+333.3%
Output Tokens10582804+165.0%11033362+204.8%
Reasoning / Thinking Tokens5321390+161.3%4741502+216.9%
Total Input Tokens100072336366+236.1%101629533931+425.4%
Cached Input Tokens86784308224+255.2%88832498432+461.1%
Uncached Input Tokens1328828142+111.8%1279735499+177.4%
Cost0.15750.4206+167.0%0.15570.5726+267.8%
Cached vs Uncached Token Ratio6.53:110.95:1+67.7%6.94:114.04:1+102.3%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 11 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!go.mod'"' -g '"'!go.sum'"' | sort && \
sed -n '1,200p' main.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*go.mod'"' -g '"'!*go.sum'"' | sort | sed -n '1,120p' && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,200p' main.go && \
printf '\\n--- project docs ---\\n' && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi && \
if [ -f Makefile ]; then printf '\\n--- Makefile ---\\n'; sed -n '1,200p' Makefile; fi"
2✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
go test ./... && \
go run . && \
git diff -- main.go go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc "git status --short && \
sed -n '1,120p' main.go"
✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go && \
printf '\\n--- git diff ---\\n' && \
git diff -- main.go && \
printf '\\n--- go files ---\\n' && \
rg --files -g '*.go' -g '"'!go.mod'"' -g '"'!go.sum'"'"
4—✓ ✓
/bin/zsh -lc 'mkdir -p docs'
5—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand"
  ]
}
6—✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go && \
printf '\\n--- status ---\\n' && \
git status --short && \
printf '\\n--- diff ---\\n' && \
git diff -- main.go docs/SUBOPTIMAL_TOOLS.md"
7—✓ ✓
/bin/zsh -lc "ls -la && \
printf '\\n--- local metadata ---\\n' && \
find . -maxdepth 2 -type f -print | sort && \
printf '\\n--- module files ---\\n' && \
ls -l go.mod go.sum 2>/dev/null || \
true"
8—semedit/semantic_verify (✓ ✓)
{
  "path": "main.go"
}
9—✓ ✓
/bin/zsh -lc 'go test ./... && \
output=$(go run .) && \
printf '"'program_output=%s\\n' \""'$output"'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'AGENTS*.md' -g '"'!AGENTS.override.md'"' -g 'go.mod' -g 'go.sum' && \
sed -n '1,200p' main.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS*' -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'go.mod' -g 'go.sum' -g 'docs/**'"
2✓ ✓
/bin/zsh -lc "sed -n '1,120p' go.mod && \
git status --short"
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
sed -n '1,120p' go.mod"
3✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
go run . && \
git diff -- main.go go.mod go.sum && \
git status --short -- main.go go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go; if test -f docs/SUBOPTIMAL_TOOLS.md; then sed -n '1,200p' docs/SUBOPTIMAL_TOOLS.md; else echo 'NO_SUBOPTIMAL_LOG'; fi; rg --files docs 2>/dev/null || \
true"
5—✓ ✓
/bin/zsh -lc 'mkdir -p docs && \
git status --short'
6—✓ ✓
/bin/zsh -lc 'ls -la && \
ls -la docs 2>/dev/null || \
true && \
git status --short --untracked-files=all -- main.go docs/SUBOPTIMAL_TOOLS.md go.mod go.sum'
7—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
8—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, mathrand.Intn(100)); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
9—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "mathrand math/rand"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand"
  ]
}
10—✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git diff --no-ext-diff -- main.go go.mod go.sum docs/SUBOPTIMAL_TOOLS.md"
11—? ✗
/bin/zsh -lc 'make check'
12—✓ ✓
/bin/zsh -lc 'go run .'
13—✓ ✓
/bin/zsh -lc 'go test ./... && \
git status --short --untracked-files=all -- main.go go.mod go.sum docs/SUBOPTIMAL_TOOLS.md'

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-5.6-luna/high
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency69.30s86.16s+24.3%79.46s86.74s+9.2%
Process Start → First Event0.13s0.12s—0.12s0.13s—
First Event → First Tool Call18.86s16.26s—17.48s17.58s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles79+28.6%136-53.8%
Initial Load / Discovery Turns72-71.4%132-84.6%
MCP Discovery / Schema Turns01—00—
Tool Invocations (per run)79+28.6%136-53.8%
Output Tokens25522846+11.5%32973063-7.1%
Reasoning / Thinking Tokens13531746+29.0%15681799+14.7%
Total Input Tokens178731356781+99.6%204882292505+42.8%
Cached Input Tokens135168318720+135.8%168704264704+56.9%
Uncached Input Tokens4356338061-12.6%3617827801-23.2%
Cost0.40250.4874+21.1%0.41120.4172+1.5%
Cached vs Uncached Token Ratio3.10:18.37:1+169.9%4.66:19.52:1+104.2%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 16 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd; printf '%s\\n' '--- files ---'; rg --files -g '"'!*go.sum'"' -g '"'!*go.mod'"' | sort; printf '%s\\n' '--- git status ---'; git status --short; printf '%s\\n' '--- protected files ---'; ls -l go.mod go.sum 2>/dev/null || \
true"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!AGENTS.override.md'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort && \
git status --short && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi && \
if [ -f main.go ]; then sed -n '1,200p' main.go; fi && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi"
2✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- main.go ---'; sed -n '1,200p' main.go; printf '%s\\n' '--- go.mod ---'; sed -n '1,80p' go.mod; printf '%s\\n' '--- project brief ---'; if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; else printf '%s\\n' '(absent)'; fi; printf '%s\\n' '--- make targets ---'; if [ -f Makefile ]; then sed -n '1,200p' Makefile; else printf '%s\\n' '(absent)'; fi"
cua_repl/js (✓ ✓)
{
  "code": "await cua.getState()",
  "title": "Check available computer surfaces"
}
3✓ ✓
/bin/zsh -lc 'gofmt -w main.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go"
✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go"
5✓ ✓
/bin/zsh -lc 'git diff --check; git status --short -- main.go go.mod go.sum; git diff -- go.mod go.sum'
semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand"
  ]
}
6✓ ✓
/bin/zsh -lc 'go test ./...'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
7✓ ✓
/bin/zsh -lc 'go run .'
semedit/semantic_verify (✓ ✓)
{
  "path": "main.go"
}
8—✓ ✓
/bin/zsh -lc 'git status --short -- main.go go.mod go.sum && \
git diff -- main.go'
9—✓ ✓
/bin/zsh -lc 'go run main.go'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*go.sum'"' -g '"'!go.mod'"' | sort"
✓ ✓
/bin/zsh -lc "pwd
rg --files -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'go.mod' -g 'AGENTS*.md' -g 'README*' -g 'docs/**' | sort
printf '\\n--- main.go ---\\n'
sed -n '1,200p' main.go
printf '\\n--- project brief if present ---\\n'
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi
printf '\\n--- Makefile if present ---\\n'
if [ -f Makefile ]; then sed -n '1,240p' Makefile; fi"
2✓ ✓
/bin/zsh -lc "if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi"
✓ ✓
/bin/zsh -lc "sed -n '1,120p' go.mod
git status --short
rg -n \"Hello World|text/template|rand.Int|func main\" . --glob '"'!AGENTS.override.md'"'"
3✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go 2>/dev/null || \
true"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "const templateText = \"Hello World {{.}}\\n\"\ntmpl := template.Must(template.New(\"greeting\").Parse(templateText))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4✓ ✓
/bin/zsh -lc 'git status --short && \
git diff -- main.go go.mod go.sum'
? ✗
/bin/zsh -lc "sed -n '1,160p' main.go
printf '\\n--- suboptimal tool log ---\\n'
sed -n '1,220p' docs/SUBOPTIMAL_TOOLS.md"
5✓ ✓
/bin/zsh -lc "sed -n '1,160p' go.mod"
semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand"
  ]
}
6✓ ✓
/bin/zsh -lc "rg -n \"text/template|rand\\.Int|Hello World|random integer|func main\" . --glob '"'!go.mod'"' --glob '"'!go.sum'"'"
✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go
go test ./...
go run .
printf '\\n--- protected file status ---\\n'
git diff --quiet -- go.mod go.sum && \
echo 'go.mod and go.sum unchanged'
printf '\\n--- task diff ---\\n'
git diff -- main.go docs/SUBOPTIMAL_TOOLS.md"
7✓ ✓
/bin/zsh -lc 'for f in api/router.go auth/auth.go cache/cache.go config/config.go db/db.go health/health.go logging/logging.go metrics/metrics.go models/models.go utils/utils.go; do echo "--- $f"; sed -n '"'1,120p' \""'$f"; done'
—
8✓ ✓
/bin/zsh -lc 'gofmt -w main.go'
—
9? ✗
/bin/zsh -lc 'make check'
—
10✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum && \
git status --short -- main.go go.mod go.sum'
—
11✓ ✓
/bin/zsh -lc 'go run .'
—
12✓ ✓
/bin/zsh -lc 'go test ./...'
—
13✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git ls-files --stage -- main.go && \
git status --porcelain=v1 --untracked-files=all -- main.go go.mod go.sum && \
git diff --no-ext-diff --no-textconv -- main.go"
—

Target: codex/gpt-5.6-luna/medium

crypto_rand prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-5.6-luna/medium
Prompt variantcrypto_rand
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)⚠ MCP (Large)Δ (Large)
Wall-Clock Latency45.73s80.01s+75.0%36.34s47.21sN/A
Process Start → First Event0.47s0.48s—0.12s0.13s—
First Event → First Tool Call7.29s8.50s—8.22s11.22s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%11N/A
Internal Tool Cycles49+125.0%44N/A
Initial Load / Discovery Turns42-50.0%41N/A
MCP Discovery / Schema Turns01—00—
Tool Invocations (per run)49+125.0%44N/A
Output Tokens14442190+51.7%11941635N/A
Reasoning / Thinking Tokens641879+37.1%467717N/A
Total Input Tokens121660340143+179.6%100148122679N/A
Cached Input Tokens98816276736+180.1%74496108032N/A
Uncached Input Tokens2284463407+177.6%2565214647N/A
Cost0.22620.5475+142.1%0.21530.1978N/A
Cached vs Uncached Token Ratio4.33:14.36:1+0.9%2.90:17.38:1N/A
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/AFAIL—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 19 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'AGENTS.md' -g 'AGENTS.override.md' | sort && \
sed -n '1,200p' main.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*go.mod'"' -g '"'!*go.sum'"' | sed -n '1,80p' && \
printf '%s\\n' '--- main.go ---' && \
sed -n '1,200p' main.go && \
printf '%s\\n' '--- docs ---' && \
rg --files -g 'PROJECT_BRIEF.md' -g 'docs/README.md' -g 'Makefile' -g 'AGENTS.md' | sed -n '1,80p'"
2? ✗
/bin/zsh -lc 'gofmt -w main.go && \
make check && \
go run . && \
git diff -- main.go go.mod go.sum && \
git status --short -- main.go go.mod go.sum'
cua_repl/js (✓ ✓)
{
  "code": "const s = await cua.getState(); nodeRepl.write(s)",
  "title": "Inspect semantic editing surfaces"
}
3✓ ✓
/bin/zsh -lc 'go run . && \
git diff -- main.go go.mod go.sum && \
git status --short -- main.go go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World %d\\n\"))\n\trandomValue, err := rand.Int(rand.Reader, big.NewInt(100))\n\tif err != nil {\n\t\tpanic(err)\n\t}\n\tif err := tmpl.Execute(os.Stdout, randomValue.Int64()); err != nil {\n\t\tpanic(err)\n\t}",
  "file": "main.go",
  "symbol": "main"
}
4✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git status --short && \
git diff --no-ext-diff -- main.go"
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
printf '%s\\n' '--- status ---' && \
git status --short && \
printf '%s\\n' '--- diff ---' && \
git diff -- main.go go.mod go.sum && \
printf '%s\\n' '--- compile/run ---' && \
GO111MODULE=off go run main.go"
5—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\n\trandomValue, err := rand.Int(rand.Reader, big.NewInt(100))\n\tif err != nil {\n\t\tpanic(err)\n\t}\n\tif err := tmpl.Execute(os.Stdout, randomValue.Int64()); err != nil {\n\t\tpanic(err)\n\t}",
  "file": "main.go",
  "symbol": "main"
}
6—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
7—✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
printf '%s\\n' '--- run ---' && \
GO111MODULE=off go run main.go && \
printf '%s\\n' '--- protected files ---' && \
git diff --quiet -- go.mod go.sum && \
printf '%s\\n' 'protected files unchanged' || \
exit 1 && \
printf '%s\\n' '--- tracked status for fixture ---' && \
git status --short -- main.go go.mod go.sum"
8—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "crypto/rand",
    "math/big",
    "os",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "math/big",
    "os",
    "text/template"
  ]
}
9—✓ ✓
/bin/zsh -lc "sed -n '1,80p' main.go && \
GO111MODULE=off gofmt -d main.go && \
GO111MODULE=off go run main.go >/tmp/semedit-main-output && \
sed -n '1p' /tmp/semedit-main-output && \
case \""'$(sed -n '"'1p' /tmp/semedit-main-output)\" in 'Hello World '* ) ;; * ) exit 1 ;; esac && \
git diff --quiet -- go.mod go.sum && \
printf '%s\\n' 'DONE'"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 24 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*go.mod'"' -g '"'!*go.sum'"' | head -80 && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,200p' main.go && \
printf '\\n--- Makefile/package files ---\\n' && \
rg --files -g 'Makefile' -g 'README*' -g 'PROJECT_BRIEF.md' -g 'AGENTS*.md' | sort"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!go.mod'"' -g '"'!go.sum'"' | sed -n '1,80p' && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,200p' main.go && \
printf '\\n--- docs candidates ---\\n' && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README.md' -g 'Makefile' -g 'AGENTS*.md' | sed -n '1,80p'"
2✓ ✓
/bin/zsh -lc 'gofmt -w main.go'
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- available semantic tooling ---' && \
command -v semedit || \
true && \
command -v semantic-editor || \
true && \
printf '%s\\n' '--- fixture files ---' && \
find . -maxdepth 2 -type f -not -path './.git/*' -print | sort"
3✓ ✓
/bin/zsh -lc 'git diff --check && \
git status --short -- main.go go.mod go.sum'
✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
git diff --check && \
go test ./... && \
go run .'
4✓ ✓
/bin/zsh -lc 'go run .'
✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum && \
git status --short'
⚠ Why no semantic edit tool was used
I did not discover any callable `semantic_*` tools in the available tool context, and no semedit CLI was present in the fixture. I therefore used ordinary editing, which was sufficient for this minimal `main.go` change.

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-5.6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency28.51s67.42s+136.4%50.37s71.64s+42.3%
Process Start → First Event0.12s0.44s—0.12s0.12s—
First Event → First Tool Call5.85s9.98s—11.50s7.09s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles38+166.7%38+166.7%
Initial Load / Discovery Turns31-66.7%31-66.7%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)38+166.7%38+166.7%
Output Tokens10561982+87.7%15072028+34.6%
Reasoning / Thinking Tokens509793+55.8%715738+3.2%
Total Input Tokens100080367982+267.7%121096416483+243.9%
Cached Input Tokens82688338944+309.9%87552381440+335.7%
Uncached Input Tokens1739229038+67.0%3354435043+4.5%
Cost0.17530.3979+127.0%0.27820.4489+61.4%
Cached vs Uncached Token Ratio4.75:111.67:1+145.5%2.61:110.88:1+317.0%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSFAIL—
Oracle L3: Clean BuildPASSPASS—PASSFAIL—
Oracle L4: Verification TestPASSPASS—PASSFAIL—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*AGENTS.override.md'"' -g 'main.go' -g 'Makefile' -g 'PROJECT_BRIEF.md' && \
sed -n '1,200p' main.go"
✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'AGENTS*.md' -g '"'!AGENTS.override.md'"'; printf '\\n--- main.go ---\\n'; sed -n '1,160p' main.go; printf '\\n--- project brief ---\\n'; if test -f PROJECT_BRIEF.md; then sed -n '1,200p' PROJECT_BRIEF.md; fi; printf '\\n--- status ---\\n'; git status --short"
2✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
go run main.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum && \
git status --short'
✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go; printf '\\n--- manifests ---\\n'; ls -1 go.mod go.sum Makefile 2>/dev/null || \
true; printf '\\n--- checks ---\\n'; rg -n '"'^(check|test|fmt)|make check'"' Makefile 2>/dev/null || \
true"
4—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
5—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "html/template"
  ]
}
6—✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go; printf '\\n--- go env/version ---\\n'; go version; printf '\\n--- diff ---\\n'; git diff -- main.go go.mod go.sum"
7—✓ ✓
/bin/zsh -lc "go run .; printf '\\n--- semantic verification ---\\n'"
8—semedit/semantic_verify (✓ ✓)
{
  "path": "main.go"
}
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
printf '\\n--- files ---\\n' && \
rg --files -g '"'!go.mod'"' -g '"'!go.sum'"' | head -50"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*go.mod'"' -g '"'!*go.sum'"' | sort && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi && \
if [ -f main.go ]; then sed -n '1,240p' main.go; fi"
2✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
go run main.go && \
git diff --check && \
git diff -- main.go && \
git status --short -- go.mod go.sum main.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "t := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := t.Execute(os.Stdout, rand.Int()); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git status --short && \
git ls-files --stage -- main.go && \
git diff --no-index /dev/null main.go || \
true"
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
git diff -- main.go"
4—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "t := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := t.Execute(os.Stdout, mathrand.Int()); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
5—✓ ✓
/bin/zsh -lc "sed -n '1,80p' main.go"
6—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "main.go"
}
7—✓ ✓
/bin/zsh -lc 'go run main.go && \
git diff --check && \
git status --short -- go.mod go.sum main.go'
8—✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git diff --stat && \
git status --short"

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-5.6-luna/medium
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency61.92s63.01s+1.8%54.84s88.56s+61.5%
Process Start → First Event0.12s0.12s—0.13s0.14s—
First Event → First Tool Call13.92s12.57s—15.59s14.71s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles47+75.0%513+160.0%
Initial Load / Discovery Turns41-75.0%54-20.0%
MCP Discovery / Schema Turns00—02—
Tool Invocations (per run)47+75.0%513+160.0%
Output Tokens16181773+9.6%17892760+54.3%
Reasoning / Thinking Tokens560868+55.0%8311264+52.1%
Total Input Tokens171967228466+32.9%198598503850+153.7%
Cached Input Tokens129024203776+57.9%179968466176+159.0%
Uncached Input Tokens4294324690-42.5%1863037674+102.2%
Cost0.34460.3046-11.6%0.26170.5422+107.1%
Cached vs Uncached Token Ratio3.00:18.25:1+174.7%9.66:112.37:1+28.1%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'README*' -g 'Makefile' -g '*.md' | sort"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!go.mod'"' -g '"'!go.sum'"' | sort | head -200 && \
printf '\\n--- main.go ---\\n' && \
sed -n '1,200p' main.go && \
printf '\\n--- project docs ---\\n' && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi && \
printf '\\n--- Makefile targets ---\\n' && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi"
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' AGENTS.override.md; printf '\\n--- main.go ---\\n'; sed -n '1,200p' main.go; printf '\\n--- go.mod ---\\n'; sed -n '1,120p' go.mod; printf '\\n--- git status ---\\n'; git status --short"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc "gofmt -w main.go && \
go run . && \
printf '\\n--- diff ---\\n' && \
git diff -- main.go go.mod go.sum && \
printf '\\n--- status ---\\n' && \
git status --short -- main.go go.mod go.sum"
✓ ✓
/bin/zsh -lc "sed -n '1,160p' main.go"
4✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go; git diff --no-ext-diff --no-textconv -- main.go; git ls-files --stage -- main.go; git check-ignore -v main.go || \
true"
semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand"
  ]
}
5—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "main.go"
}
6—✓ ✓
/bin/zsh -lc 'go run main.go'
7—✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum && \
git status --short'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'Makefile' -g 'main.go' -g 'README*' -g 'docs/adr/README.md' -g 'docs/research/README.md'; if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi; if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi; sed -n '1,220p' main.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'go.mod' -g 'Makefile' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g 'AGENTS.md' -g 'AGENTS.override.md' | sort"
2✓ ✓
/bin/zsh -lc "rg --files -g '"'!AGENTS.override.md'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort; git status --short"
✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
printf '\\n--- go.mod ---\\n' && \
sed -n '1,120p' go.mod && \
printf '\\n--- files ---\\n' && \
rg --files | sort"
3✓ ✓
/bin/zsh -lc 'gofmt -w main.go; go test ./...; go run .'
cua_repl/js (✓ ✓)
{
  "code": "const s = await cua.getState(); nodeRepl.write(JSON.stringify(s));",
  "title": "Inspect connected UI surfaces"
}
4✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum; git status --short -- main.go go.mod go.sum'
cua_repl/js (✓ ✓)
{
  "code": "nodeRepl.write('');",
  "title": "Continue with repository editing"
}
5✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go; git diff --no-index /dev/null main.go || \
true"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
6—✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git diff -- main.go go.mod go.sum"
7—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "html/template"
  ]
}
8—✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go"
9—? ✗
/bin/zsh -lc 'make check'
10—semedit/semantic_verify (✓ ✓)
{
  "path": "main.go"
}
11—✓ ✓
/bin/zsh -lc 'go run . && \
git diff --check && \
git diff -- main.go go.mod go.sum'
12—✓ ✓
/bin/zsh -lc 'git status --short && \
git diff -- main.go'
13—? ✗
/bin/zsh -lc 'git rev-parse --show-toplevel && \
git ls-files --error-unmatch main.go && \
git diff --no-ext-diff -- main.go && \
git status --short --untracked-files=all -- main.go go.mod go.sum'

Target: codex/gpt-6-luna/high

crypto_rand prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/high
Prompt variantcrypto_rand
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency36.14s73.74s+104.0%53.49s80.79s+51.0%
Process Start → First Event0.13s0.12s—0.12s0.12s—
First Event → First Tool Call4.81s6.66s—7.65s6.70s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles48+100.0%310+233.3%
Initial Load / Discovery Turns220%32-33.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)48+100.0%310+233.3%
Output Tokens13561640+20.9%10472290+118.7%
Reasoning / Thinking Tokens778989+27.1%4661595+242.3%
Total Input Tokens97013192564+98.5%99710244881+145.6%
Cached Input Tokens85760177920+107.5%88832226560+155.0%
Uncached Input Tokens1125314644+30.1%1087818321+68.4%
Cost0.07620.1140+49.5%0.06830.1510+121.0%
Cached vs Uncached Token Ratio7.62:112.15:1+59.4%8.17:112.37:1+51.4%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 23 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'AGENTS*' -g 'PROJECT_BRIEF.md'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'Makefile' -g 'go.mod' -g 'go.sum' -g 'docs/**'"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
✓ ✓
/bin/zsh -lc 'cat main.go'
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile

path = Path('main.go')
source = '''package main

import (
	\"crypto/rand\"
	\"math/big\"
	\"os\"
	\"text/template\"
)

func main() {
	n, err := rand.Int(rand.Reader, big.NewInt(100))
	if err "'!= nil {
		panic(err)
	}

	tmpl, err := template.New("greeting").Parse("Hello World {{.}}'"\\\\n\")
	if err "'!= nil {
		panic(err)
	}
	if err := tmpl.Execute(os.Stdout, n); err != nil {
		panic(err)
	}
}
'"'''
old_mtime = path.stat().st_mtime_ns
fd, temp_name = tempfile.mkstemp(dir=path.parent, prefix='.main.go.')
try:
    with os.fdopen(fd, 'w', encoding='utf-8', newline='') as f:
        f.write(source)
        f.flush()
        os.fsync(f.fileno())
    os.replace(temp_name, path)
    new_time = max(path.stat().st_mtime_ns, old_mtime + 1_000_000)
    os.utime(path, ns=(new_time, new_time))
finally:
    if os.path.exists(temp_name):
        os.unlink(temp_name)
PY

git diff -- main.go go.mod go.sum"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "randomNumber, err := rand.Int(rand.Reader, big.NewInt(100))\nif err != nil {\n\tlog.Fatal(err)\n}\n\ngreeting := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := greeting.Execute(os.Stdout, randomNumber); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short && \
rg --files'
✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short -- main.go go.mod go.sum'
5—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
6—✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short -- main.go go.mod go.sum'
7—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "crypto/rand",
    "log",
    "math/big",
    "os",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "log",
    "math/big",
    "os",
    "text/template"
  ]
}
8—✓ ✓
/bin/zsh -lc "sed -n '1,24p' main.go"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 24 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g 'AGENTS.override.md'"
2✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
git diff -- main.go go.mod go.sum'
✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short'
3? ✗
/bin/zsh -lc "sed -n '1,160p' main.go && \
git status --short -- main.go go.mod go.sum && \
git diff --no-index /dev/null main.go"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "randomInt, err := rand.Int(rand.Reader, big.NewInt(100))\nif err != nil {\n\tlog.Fatal(err)\n}\n\ngreeting, err := template.New(\"greeting\").Parse(\"Hello World: {{.}}\\n\")\nif err != nil {\n\tlog.Fatal(err)\n}\nif err := greeting.Execute(os.Stdout, randomInt); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
5—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
6—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
7—semedit/semantic_organize_imports (✓ ✓)
{
  "file": "main.go"
}
8—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
9—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "crypto/rand",
    "log",
    "math/big",
    "os",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "log",
    "math/big",
    "os",
    "text/template"
  ]
}
10—✓ ✓
/bin/zsh -lc 'cat main.go'

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency38.19s93.86s+145.8%28.49s46.62s+63.6%
Process Start → First Event0.12s0.12s—0.13s0.12s—
First Event → First Tool Call8.81s7.55s—5.52s5.77s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles411+175.0%35+66.7%
Initial Load / Discovery Turns43-25.0%21-50.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)411+175.0%35+66.7%
Output Tokens10362908+180.7%818861+5.3%
Reasoning / Thinking Tokens6511801+176.7%408466+14.2%
Total Input Tokens115958265373+128.9%77501155964+101.2%
Cached Input Tokens104960231424+120.5%67584136448+101.9%
Uncached Input Tokens1099833949+208.7%991719516+96.8%
Cost0.07480.2016+169.4%0.05700.0995+74.5%
Cached vs Uncached Token Ratio9.54:16.82:1-28.6%6.81:16.99:1+2.6%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS*' -g 'README*' -g 'go.mod' -g 'go.sum'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'go.sum' -g 'Makefile'"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
✓ ✓
/bin/zsh -lc 'cat main.go'
3✓ ✓
/bin/zsh -lc 'gofmt -d main.go && \
git diff -- main.go go.mod go.sum'
✓ ✓
/bin/zsh -lc 'cat go.mod'
4✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
5—? ✗
/bin/zsh -lc "cat main.go && \
rg --files | rg '("'^|/)SUBOPTIMAL_TOOLS'"\\.md"'$'"'"
6—✓ ✓
/bin/zsh -lc "rg --files -g 'SUBOPTIMAL_TOOLS.md' -g 'docs/**' | head -30; ls"
7—✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import tempfile
from pathlib import Path

path = Path('docs/SUBOPTIMAL_TOOLS.md')
path.parent.mkdir(parents=True, exist_ok=True)
content = \"\"\"# Suboptimal Tool Behavior

## 2026-09-24: "'`semantic_replace_body` import inference

- Tool: `semantic_replace_body` with `auto_organize_imports: true`
- Target: `main.go`
- Observed failure: The edit required `text/template` and a random integer, but import organization selected `html/template` and `crypto/rand`. Verification then reported that `crypto/rand.Int` requires arguments.
- Workaround: Correct the imports explicitly to `text/template` and `math/rand`, then re-run semantic import organization.
- Root cause: Automatic import resolution chose unintended packages for ambiguous identifiers.
"""
fd, temp_name = tempfile.mkstemp(prefix='"'.SUBOPTIMAL_TOOLS.', dir=path.parent)
try:
    with os.fdopen(fd, 'w') as f:
        f.write(content)
        f.flush()
        os.fsync(f.fileno())
    os.replace(temp_name, path)
    os.utime(path, None)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY"
8—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "html/template"
  ]
}
9—semedit/semantic_replace_body (✓ ✓)
{
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
10—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go docs/SUBOPTIMAL_TOOLS.md'
11—✓ ✓
/bin/zsh -lc 'git status --short'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'go.mod' -g 'go.sum'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS*' -g 'PROJECT_BRIEF.md' -g 'Makefile' -g '*semantic*' -g '*.md' | head -80 && \
sed -n '1,200p' main.go"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod && \
git status --short'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"hello\").Parse(\"Hello World {{.}}\\n\"))\n\tif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\t\tlog.Fatal(err)\n\t}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc "python3 -c 'import os, tempfile; p=\"main.go\"; data=\"\"\"package main

import (
	\\\"log\\\"
	\\\"math/rand\\\"
	\\\"os\\\"
	\\\"text/template\\\"
)

func main() {
	tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\\\n\"))
	if err := tmpl.Execute(os.Stdout, rand.Intn(100)); err "'!= nil {
		log.Fatal(err)
	}
}
"""; fd, tmp = tempfile.mkstemp(prefix=".main.go.", dir=".");
f = os.fdopen(fd, "w"); f.write(data); f.flush(); os.fsync(f.fileno()); f.close(); os.replace(tmp, p); d=os.open(".", os.O_RDONLY); os.fsync(d); os.close(d)'"' && \
cat main.go"
✓ ✓
/bin/zsh -lc 'cat main.go'
4—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
5—✓ ✓
/bin/zsh -lc 'cat main.go'

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/high
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency69.75s30.03s-56.9%58.38s47.40s-18.8%
Process Start → First Event0.12s0.13s—0.12s0.12s—
First Event → First Tool Call18.73s10.00s—19.89s15.96s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles63-50.0%63-50.0%
Initial Load / Discovery Turns61-83.3%61-83.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)63-50.0%63-50.0%
Output Tokens1979927-53.2%23531636-30.5%
Reasoning / Thinking Tokens1361554-59.3%15191077-29.1%
Total Input Tokens285897152347-46.7%196430190868-2.8%
Cached Input Tokens261632126720-51.6%173312163328-5.8%
Uncached Input Tokens2426525627+5.6%2311827540+19.1%
Cost0.16780.1143-31.9%0.14950.1436-4.0%
Cached vs Uncached Token Ratio10.78:14.94:1-54.1%7.50:15.93:1-20.9%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'AGENTS*' -g 'PROJECT_BRIEF.md'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' | sort && \
cat main.go"
2✓ ✓
/bin/zsh -lc 'cat main.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc 'gofmt -w main.go'
✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
4✓ ✓
/bin/zsh -lc 'git diff -- main.go'
—
5✓ ✓
/bin/zsh -lc 'git status --short && \
cat main.go'
—
6✓ ✓
/bin/zsh -lc 'git status --short -- main.go && \
git check-ignore -v main.go'
—
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc 'cat main.go'
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'Makefile' | sort && \
git status --short && \
sed -n '1,200p' main.go"
2✓ ✓
/bin/zsh -lc 'git status --short -- main.go go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc 'git diff -- main.go'
✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go"
4✓ ✓
/bin/zsh -lc 'git status --short -- main.go go.mod go.sum'
—
5✓ ✓
/bin/zsh -lc 'cat main.go'
—
6✓ ✓
/bin/zsh -lc 'git status --short'
—

Target: codex/gpt-6-luna/medium

crypto_rand prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/medium
Prompt variantcrypto_rand
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency17.66s22.03s+24.7%17.22s27.93s+62.2%
Process Start → First Event0.12s0.16s—0.12s0.14s—
First Event → First Tool Call4.81s5.46s—4.69s7.46s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles330%24+100.0%
Initial Load / Discovery Turns31-66.7%220%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)330%24+100.0%
Output Tokens417388-7.0%491465-5.3%
Reasoning / Thinking Tokens00—1590-100.0%
Total Input Tokens77113107072+38.9%75514109919+45.6%
Cached Input Tokens6758492928+37.5%6656097024+45.8%
Uncached Input Tokens952914144+48.4%895412895+44.0%
Cost0.04590.0634+38.1%0.04710.0623+32.1%
Cached vs Uncached Token Ratio7.09:16.57:1-7.4%7.43:17.52:1+1.2%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 26 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'Makefile'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g 'Makefile' -g '*semantic*' | head -80 && \
sed -n '1,160p' main.go"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod && \
git status --short'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "n, err := rand.Int(rand.Reader, big.NewInt(100))\nif err != nil {\n\tfmt.Fprintln(os.Stderr, err)\n\tos.Exit(1)\n}\ntmpl, err := template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\")\nif err != nil {\n\tfmt.Fprintln(os.Stderr, err)\n\tos.Exit(1)\n}\nif err := tmpl.Execute(os.Stdout, n); err != nil {\n\tfmt.Fprintln(os.Stderr, err)\n\tos.Exit(1)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc 'gofmt -w main.go && \
go run main.go'
✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git status --short"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 20 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'AGENTS*' -g 'PROJECT_BRIEF.md'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'Makefile' -g 'docs/**' -g 'README*' | head -80"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
✓ ✓
/bin/zsh -lc 'cat main.go'
3—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "var value [8]byte\nif _, err := rand.Read(value[:]); err != nil {\n\tpanic(err)\n}\nnumber := binary.LittleEndian.Uint64(value[:])\ntmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, number); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short -- main.go go.mod go.sum'

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency14.19s37.67s+165.4%14.34s83.85s+484.7%
Process Start → First Event0.12s0.12s—0.13s0.12s—
First Event → First Tool Call4.97s5.32s—4.66s16.03s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles26+200.0%25+150.0%
Initial Load / Discovery Turns220%21-50.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)26+200.0%25+150.0%
Output Tokens324926+185.8%332727+119.0%
Reasoning / Thinking Tokens0350—0252—
Total Input Tokens75340156745+108.1%76936148080+92.5%
Cached Input Tokens66560132352+98.8%67584132352+95.8%
Uncached Input Tokens878024393+177.8%935215728+68.2%
Cost0.04260.1100+158.0%0.04440.0846+90.5%
Cached vs Uncached Token Ratio7.58:15.43:1-28.4%7.23:18.42:1+16.4%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 12 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'README*' -g 'go.mod' -g 'go.sum'"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
3—semedit/semantic_replace_body (✓ ✗): syntax error: expected '}', found 'EOF'
{
  "auto_organize_imports": true,
  "body": "data := struct {\n\tMessage string\n\tNumber  int\n}{\n\tMessage: \"Hello World\",\n\tNumber:  rand.Intn(100),\n}\n\ntmpl, err := template.New(\"greeting\").Parse(\"{{.Message}} {{.Number}}\\n\")\nif err != nil {\n\tlog.Fatal(err)\n}\n\nif err := tmpl.Execute(os.Stdout, data); err != nil {\n\tlog.Fatal(err)\n",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'rg --files'
5—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
6—✓ ✓
/bin/zsh -lc 'cat main.go && \
go run .'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'Makefile' -g 'README*' -g 'go.mod' -g 'AGENTS*'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS*' -g 'PROJECT_BRIEF.md' -g 'Makefile' -g 'go.mod' -g '*.md' | head -80"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod && \
git status --short'
? ✗
/bin/zsh -lc 'cat main.go && \
cat go.mod && \
rg -n "semantic_(replace_body|organize_imports)|semantic_replace_body" .'
3—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\\\n\"))\n\tif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\t\tlog.Fatal(err)\n\t}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
5—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\n\tif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\t\tlog.Fatal(err)\n\t}",
  "file": "main.go",
  "symbol": "main"
}

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/medium
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency30.55s53.34s+74.6%29.22s54.07s+85.0%
Process Start → First Event0.12s0.12s—0.13s0.12s—
First Event → First Tool Call11.05s5.79s—11.36s7.68s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles37+133.3%38+166.7%
Initial Load / Discovery Turns220%32-33.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)37+133.3%38+166.7%
Output Tokens6871279+86.2%9441249+32.3%
Reasoning / Thinking Tokens244718+194.3%508630+24.0%
Total Input Tokens99454211631+112.8%187300275643+47.2%
Cached Input Tokens87808188416+114.6%164096251392+53.2%
Uncached Input Tokens1164623215+99.3%2320424251+4.5%
Cost0.06270.1301+107.5%0.11720.1470+25.4%
Cached vs Uncached Token Ratio7.54:18.12:1+7.6%7.07:110.37:1+46.6%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSFAIL—
Oracle L3: Clean BuildPASSPASS—PASSFAIL—
Oracle L4: Verification TestPASSPASS—PASSFAIL—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g '"'!go.mod'"' -g '"'!go.sum'"' -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'go.sum' -g 'Makefile' -g 'README*'"
2✓ ✓
/bin/zsh -lc 'cat main.go'
✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
p = Path('main.go')
data = '''package main

import (
	\"math/rand\"
	\"os\"
	\"text/template\"
)

func main() {
	tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\\\n\"))
	if err := tmpl.Execute(os.Stdout, rand.Int()); err "'!= nil {
		panic(err)
	}
}
'"'''
tmp = p.with_name(p.name + '.tmp')
with tmp.open('w') as f:
    f.write(data)
    f.flush()
    os.fsync(f.fileno())
os.replace(tmp, p)
PY
cat main.go"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, mathrand.Intn(100)); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
5—✓ ✓
/bin/zsh -lc 'cat main.go && \
rg --files'
6—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "mathrand \"math/rand\""
  ],
  "file": "main.go"
}
7—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'AGENTS*' | sort && \
cat main.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g 'main.go' -g 'Makefile' -g 'go.mod' | sort"
2✓ ✓
/bin/zsh -lc 'cat go.mod && \
git status --short'
✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short'
3✓ ✓
/bin/zsh -lc 'gofmt -d main.go && \
git diff -- main.go go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
5—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "mathrand math/rand"
  ],
  "file": "main.go"
}
6—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, mathrand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
7—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "mathrand math/rand"
  ],
  "file": "main.go"
}
8—✓ ✓
/bin/zsh -lc 'cat main.go && \
go run .'

Target: codex/gpt-6-luna/xhigh

crypto_rand prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/xhigh
Prompt variantcrypto_rand
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer from crypto/rand, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency72.50s136.70s+88.6%59.82s158.55s+165.0%
Process Start → First Event0.13s0.13s—0.12s0.11s—
First Event → First Tool Call25.34s8.70s—9.63s7.19s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles38+166.7%310+233.3%
Initial Load / Discovery Turns220%110%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)38+166.7%310+233.3%
Output Tokens18115485+202.9%27157221+166.0%
Reasoning / Thinking Tokens12534669+272.6%20106039+200.4%
Total Input Tokens78730253949+222.6%82140261461+218.3%
Cached Input Tokens67584230912+241.7%70656226816+221.0%
Uncached Input Tokens1114623037+106.7%1148434645+201.7%
Cost0.08310.2422+191.6%0.10540.3091+193.1%
Cached vs Uncached Token Ratio6.06:110.02:1+65.3%6.15:16.55:1+6.4%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 22 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'go.mod' -g 'go.sum'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS*' -g 'main.go' -g 'go.mod' -g 'go.sum' -g 'README*' -g 'Makefile'"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short'
✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import stat
import tempfile
from pathlib import Path

path = Path('main.go')
content = '''package main

import (
\\t\"crypto/rand\"
\\t\"log\"
\\t\"math/big\"
\\t\"os\"
\\t\"text/template\"
)

func main() {
\\trandomInt, err := rand.Int(rand.Reader, big.NewInt(100))
\\tif err "'!= nil {
'"\\t\\tlog.Fatal(err)
\\t}

\\toutput := template.Must(template.New(\"greeting\").Parse(\"Hello World"'! Random integer: {{.}}'"\\\\n\"))
\\tif err := output.Execute(os.Stdout, randomInt); err "'!= nil {
'"\\t\\tlog.Fatal(err)
\\t}
}
'''
mode = stat.S_IMODE(path.stat().st_mode)
fd, temporary = tempfile.mkstemp(dir=path.parent, prefix='.main.go.')
try:
    with os.fdopen(fd, 'w', encoding='utf-8', newline='') as stream:
        stream.write(content)
        stream.flush()
        os.fsync(stream.fileno())
    os.chmod(temporary, mode)
    os.replace(temporary, path)
    directory_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(directory_fd)
    finally:
        os.close(directory_fd)
except BaseException:
    try:
        os.unlink(temporary)
    except FileNotFoundError:
        pass
    raise
PY
cat main.go"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "n, err := rand.Int(rand.Reader, big.NewInt(100))\nif err != nil {\n\tlog.Fatal(err)\n}\n\ntmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, n.Int64()); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
git status --short && \
git diff -- main.go go.mod go.sum'
5—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
6—✓ ✓
/bin/zsh -lc 'cat main.go && \
cat docs/SUBOPTIMAL_TOOLS.md && \
git diff -- main.go go.mod go.sum docs/SUBOPTIMAL_TOOLS.md'
7—semedit/semantic_organize_imports (✓ ✓)
{
  "file": "main.go"
}
8—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- go.mod go.sum && \
test ! -e go.sum'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 25 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g '"'!go.mod'"' -g '"'!go.sum'"' | head -80 && \
sed -n '1,200p' main.go"
2✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import pathlib
import tempfile
import time

path = pathlib.Path('main.go')
previous_mtime_ns = path.stat().st_mtime_ns
content = '''package main

import (
	\"crypto/rand\"
	\"math/big\"
	\"os\"
	\"text/template\"
)

func main() {
	n, err := rand.Int(rand.Reader, big.NewInt(100))
	if err "'!= nil {
		panic(err)
	}

	tmpl := template.Must(template.New("greeting").Parse("Hello World: {{.}}'"\\\\n\"))
	if err := tmpl.Execute(os.Stdout, n); err "'!= nil {
		panic(err)
	}
}
'"'''
fd, temp_name = tempfile.mkstemp(prefix='.main.go.', dir=path.parent)
try:
    with os.fdopen(fd, 'wb') as temp_file:
        temp_file.write(content.encode())
        temp_file.flush()
        os.fsync(temp_file.fileno())
    os.replace(temp_name, path)
    mtime_ns = max(time.time_ns(), previous_mtime_ns + 1)
    os.utime(path, ns=(mtime_ns, mtime_ns))
    with path.open('rb') as updated:
        os.fsync(updated.fileno())
    dir_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(dir_fd)
    finally:
        os.close(dir_fd)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY

gofmt -w main.go
sed -n '1,120p' main.go"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "n, err := rand.Int(rand.Reader, big.NewInt(1000))\nif err != nil {\n\tlog.Fatal(err)\n}\n\ntmpl, err := template.New(\"hello\").Parse(\"Hello World (random integer: {{.}})\\n\")\nif err != nil {\n\tlog.Fatal(err)\n}\n\nif err := tmpl.Execute(os.Stdout, n); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum'
✓ ✓
/bin/zsh -lc "sed -n '1,120p' main.go && \
git diff -- main.go go.mod go.sum"
4—✓ ✓
/bin/zsh -lc "if [ -f docs/SUBOPTIMAL_TOOLS.md ]; then sed -n '1,180p' docs/SUBOPTIMAL_TOOLS.md; else printf '%s\\n' 'MISSING'; fi"
5—✓ ✓
/bin/zsh -lc 'pwd && \
rg --files | head -80'
6—✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
from pathlib import Path
import tempfile

directory = Path('docs')
directory.mkdir(exist_ok=True)
target = directory / 'SUBOPTIMAL_TOOLS.md'
content = \"\"\"# Suboptimal Tool Behavior

This log records semantic editor tool failures and the workarounds used in this workspace.

## 2026-09-24

- Tool: "'`semantic_replace_body` import organization in `main.go`.
- Observed failure: `auto_organize_imports` selected `html/template` for code that requires the requested `text/template` package.
- Workaround applied: Explicitly replace `html/template` with `text/template` using `semantic_organize_imports`.
- Root cause: The import organizer resolved the ambiguous `template` package name to the wrong standard library package.
"""
with tempfile.NamedTemporaryFile(mode='"'w', encoding='utf-8', dir=directory, prefix='.SUBOPTIMAL_TOOLS.', delete=False) as stream:
    temp_path = Path(stream.name)
    stream.write(content)
    stream.flush()
    os.fsync(stream.fileno())
os.replace(temp_path, target)
dir_fd = os.open(directory, os.O_RDONLY)
try:
    os.fsync(dir_fd)
finally:
    os.close(dir_fd)
PY"
7—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
8—✓ ✓
/bin/zsh -lc "sed -n '1,100p' main.go && \
git status --short && \
git diff -- main.go docs/SUBOPTIMAL_TOOLS.md go.mod go.sum"
9—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "crypto/rand",
    "log",
    "math/big",
    "os",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "log",
    "math/big",
    "os",
    "text/template"
  ]
}
10—? ✗
/bin/zsh -lc "sed -n '1,100p' main.go && \
cat docs/SUBOPTIMAL_TOOLS.md && \
stat -f '%Sm %N' -t '%Y-%m-%d %H:%M:%S' go.mod go.sum"

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/xhigh
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency38.38s62.48s+62.8%39.00s170.07s+336.1%
Process Start → First Event0.12s0.12s—0.12s0.14s—
First Event → First Tool Call7.02s9.65s—6.98s10.73s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles34+33.3%29+350.0%
Initial Load / Discovery Turns220%12+100.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)34+33.3%29+350.0%
Output Tokens16031984+23.8%17304732+173.5%
Reasoning / Thinking Tokens11221611+43.6%12783702+189.7%
Total Input Tokens76768124523+62.2%57715237569+311.6%
Cached Input Tokens62464104192+66.8%48384217600+349.7%
Uncached Input Tokens1430420331+42.1%933119969+114.0%
Cost0.08540.1218+42.6%0.07300.2097+187.2%
Cached vs Uncached Token Ratio4.37:15.12:1+17.4%5.19:110.90:1+110.1%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'go.sum'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'go.mod' -g 'go.sum'"
2✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
✓ ✓
/bin/zsh -lc 'cat main.go'
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile

path = Path('main.go')
content = '''// Package main runs the greeting template as the application entry point.
package main

import (
	\"math/rand\"
	\"os\"
	\"text/template\"
)

func main() {
	greeting := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\\\n\"))
	if err := greeting.Execute(os.Stdout, rand.Intn(100)); err "'!= nil {
		panic(err)
	}
}
'"'''
fd, temp_name = tempfile.mkstemp(prefix='.main.go.', dir='.')
try:
    with os.fdopen(fd, 'w') as f:
        f.write(content)
        f.flush()
        os.fsync(f.fileno())
    os.replace(temp_name, path)
    dir_fd = os.open('.', os.O_RDONLY)
    try:
        os.fsync(dir_fd)
    finally:
        os.close(dir_fd)
except Exception:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY
cat main.go
git diff -- main.go go.mod go.sum"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod && \
git status --short && \
git diff -- go.mod go.sum'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 18 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 18 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "sed -n '1,200p' main.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'go.sum'"
2✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import tempfile
from pathlib import Path

path = Path('main.go')
content = '''package main

import (
	\"log\"
	\"math/rand\"
	\"os\"
	\"text/template\"
)

func main() {
	tmpl, err := template.New(\"greeting\").Parse(\"Hello World {{.}}\\\\n\")
	if err "'!= nil {
		log.Fatal(err)
	}
	if err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {
		log.Fatal(err)
	}
}
'"'''
fd, temp_name = tempfile.mkstemp(dir=path.parent, prefix='.main.go.')
try:
    with os.fdopen(fd, 'w') as temp_file:
        temp_file.write(content)
        temp_file.flush()
        os.fsync(temp_file.fileno())
    os.replace(temp_name, path)
finally:
    if os.path.exists(temp_name):
        os.unlink(temp_name)
PY
sed -n '1,120p' main.go"
✓ ✓
/bin/zsh -lc 'cat main.go'
3—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl, err := template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\")\nif err != nil {\n\tlog.Fatal(err)\n}\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go go.mod go.sum'
5—✓ ✓
/bin/zsh -lc "if [ -f docs/SUBOPTIMAL_TOOLS.md ]; then cat docs/SUBOPTIMAL_TOOLS.md; else printf 'MISSING\\n'; fi"
6—✓ ✓
/bin/zsh -lc "rg --files -g 'docs/**' -g 'AGENTS.md' -g 'AGENTS.override.md'"
7—✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile

path = Path('docs/SUBOPTIMAL_TOOLS.md')
path.parent.mkdir(parents=True, exist_ok=True)
content = '''<"'!-- This log records semantic editor failures so they can be diagnosed and avoided. -->

# Suboptimal tool behavior

## 2026-09-24: semantic import inference selected the wrong template package

- Tool: `semantic_replace_body` with automatic import organization enabled.
- Target: `main.go`.
- Observed failure: import inference added `html/template` although the request explicitly required `text/template`.
- Workaround: replace the inferred import with an explicit `text/template` import using semantic import organization.
- Root cause: the body used the unqualified identifier `template`, and automatic import inference selected a package without preserving the requested package distinction.
'"'''
fd, temp_name = tempfile.mkstemp(prefix='.SUBOPTIMAL_TOOLS.', dir=path.parent)
try:
    with os.fdopen(fd, 'w', encoding='utf-8') as temp_file:
        temp_file.write(content)
        temp_file.flush()
        os.fsync(temp_file.fileno())
    os.replace(temp_name, path)
    dir_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(dir_fd)
    finally:
        os.close(dir_fd)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY"
8—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
9—✓ ✓
/bin/zsh -lc 'cat main.go && \
git diff -- main.go docs/SUBOPTIMAL_TOOLS.md go.mod go.sum && \
git status --short'

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-07-generate-template-main
Targetcodex/gpt-6-luna/xhigh
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/scripts/generate_template_main.txtar

Vanilla LLM Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. In main.go, implement main() to execute a text/template that prints ‘Hello World’ along with a random integer, ensuring all necessary standard library packages are imported cleanly. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package main

func main() {
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency52.27s98.25s+88.0%67.18s182.12s+171.1%
Process Start → First Event0.13s0.12s—0.14s0.12s—
First Event → First Tool Call20.26s22.94s—27.33s20.87s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles25+150.0%310+233.3%
Initial Load / Discovery Turns21-50.0%220%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)25+150.0%310+233.3%
Output Tokens23343611+54.7%28288698+207.6%
Reasoning / Thinking Tokens17672918+65.1%22437140+218.3%
Total Input Tokens166451286899+72.4%138467379903+174.4%
Cached Input Tokens144896252928+74.6%115456346112+199.8%
Uncached Input Tokens2155533971+57.6%2301133791+46.8%
Cost0.14140.2298+62.5%0.14980.3690+146.3%
Cached vs Uncached Token Ratio6.72:17.45:1+10.8%5.02:110.24:1+104.1%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File main.go modified (4 lines -> 14 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc 'cat main.go'
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'main.go' -g 'PROJECT_BRIEF.md' -g 'README*' -g 'AGENTS.md' -g 'AGENTS.override.md' && \
git status --short && \
cat main.go"
2✓ ✓
/bin/zsh -lc 'cat main.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Int()); err != nil {\n\tpanic(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
3—✓ ✓
/bin/zsh -lc 'cat main.go'
4—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "math/rand",
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "crypto/rand",
    "html/template"
  ]
}
5—✓ ✓
/bin/zsh -lc 'cat main.go'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 19 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File main.go modified (4 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc 'cat main.go'
✓ ✓
/bin/zsh -lc "rg --files -g 'main.go' -g 'go.mod' -g 'AGENTS*'"
2✓ ✓
/bin/zsh -lc 'git status --short'
✓ ✓
/bin/zsh -lc 'cat main.go && \
cat go.mod'
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import tempfile
from pathlib import Path

path = Path('main.go')
content = '''// Package main exists as a runnable example of rendering a template with random input.
package main

import (
	\"math/rand\"
	\"os\"
	\"text/template\"
)

func main() {
	greeting, err := template.New(\"greeting\").Parse(\"Hello World {{.}}\\\\n\")
	if err "'!= nil {
		panic(err)
	}

	if err := greeting.Execute(os.Stdout, rand.Intn(100)); err != nil {
		panic(err)
	}
}
'"'''
fd, temp_name = tempfile.mkstemp(prefix='.main.go.', dir=path.parent)
try:
    with os.fdopen(fd, 'w') as temp_file:
        temp_file.write(content)
        temp_file.flush()
        os.fsync(temp_file.fileno())
    os.replace(temp_name, path)
    dir_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(dir_fd)
    finally:
        os.close(dir_fd)
finally:
    if os.path.exists(temp_name):
        os.unlink(temp_name)
PY
cat main.go"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "tmpl := template.Must(template.New(\"greeting\").Parse(\"Hello World! Random number: {{.}}\\n\"))\nif err := tmpl.Execute(os.Stdout, rand.Intn(100)); err != nil {\n\tlog.Fatal(err)\n}",
  "file": "main.go",
  "symbol": "main"
}
4—✓ ✓
/bin/zsh -lc 'cat main.go'
5—✓ ✓
/bin/zsh -lc 'git diff -- main.go go.mod go.sum'
6—? ✗
/bin/zsh -lc "rg --files -g 'SUBOPTIMAL_TOOLS.md'"
7—✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile

directory = Path('docs')
directory.mkdir(exist_ok=True)
target = directory / 'SUBOPTIMAL_TOOLS.md'
content = '''# Suboptimal Tool Behavior

## 2026-09-24: semantic import selection

- Tool: "'`semantic_replace_body` with automatic import organization.
- Target: `main.go`.
- Observed failure: the organizer added `html/template`, although the requested implementation uses `text/template`.
- Workaround: use `semantic_organize_imports` to remove `html/template` and add `text/template` explicitly.
- Root cause: automatic import resolution chose the HTML template package for the ambiguous `template` identifier without accounting for the requested package.
'"'''
fd, temporary = tempfile.mkstemp(prefix='.SUBOPTIMAL_TOOLS.', dir=directory)
try:
    with os.fdopen(fd, 'w', encoding='utf-8') as stream:
        stream.write(content)
        stream.flush()
        os.fsync(stream.fileno())
    os.replace(temporary, target)
    directory_fd = os.open(directory, os.O_RDONLY)
    try:
        os.fsync(directory_fd)
    finally:
        os.close(directory_fd)
except BaseException:
    try:
        os.unlink(temporary)
    except FileNotFoundError:
        pass
    raise
PY"
8—semedit/semantic_organize_imports (✓ ✓)
{
  "add": [
    "text/template"
  ],
  "file": "main.go",
  "remove": [
    "html/template"
  ]
}
9—✓ ✓
/bin/zsh -lc 'cat main.go'
10—✓ ✓
/bin/zsh -lc 'git status --short'

Test case: task-09-composite-refactor

Target: codex/gpt-5.6-luna/high

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-09-composite-refactor
Targetcodex/gpt-5.6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_09_composite_refactor.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package config

import (
	"archive/tar"
	"fmt"
)

type Config struct {
	Host string
	Port int
}

func (c *Config) Addr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.Port)
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency44.40s78.92s+77.7%45.85s79.08s+72.5%
Process Start → First Event0.12s0.14s—0.12s0.12s—
First Event → First Tool Call7.99s8.02s—8.98s8.27s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles410+150.0%68+33.3%
Initial Load / Discovery Turns41-75.0%62-66.7%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)410+150.0%68+33.3%
Output Tokens17402349+35.0%17242720+57.8%
Reasoning / Thinking Tokens751954+27.0%5531325+139.6%
Total Input Tokens124885333236+166.8%167097274387+64.2%
Cached Input Tokens110080290816+164.2%151552241152+59.1%
Uncached Input Tokens1480542420+186.5%1554533235+113.8%
Cost0.20380.4566+124.0%0.22180.4081+84.0%
Cached vs Uncached Token Ratio7.44:16.86:1-7.8%9.75:17.26:1-25.6%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS*.md' -g 'Makefile' -g 'config/config.go' -g '*.go' | sort && \
printf '\\n--- config/config.go ---\\n' && \
sed -n '1,240p' config/config.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS*.md' -g 'Makefile' -g 'go.mod' -g 'go.sum' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g '.codex/**' | sort && \
sed -n '1,220p' config/config.go && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,220p' PROJECT_BRIEF.md; fi && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi"
2✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- config/config_test.go ---' && \
sed -n '1,240p' config/config_test.go && \
printf '%s\\n' '--- git status ---' && \
git status --short && \
printf '%s\\n' '--- tracked files ---' && \
git ls-files"
✓ ✓
/bin/zsh -lc "rg --files -g '"'!AGENTS.override.md'"' | sort && \
printf '%s\\n' '--- go.mod ---' && \
sed -n '1,160p' go.mod && \
printf '%s\\n' '--- references ---' && \
rg -n '\\.Port\\b|Config\\{|DefaultConfig|semantic_(rename|insert|replace|batch)|semedit' -g '*.go' -g '*.md' -g '*.txtar' . || \
true"
3✓ ✓
/bin/zsh -lc "gofmt -w config/config.go && \
printf '%s\\n' '--- config/config.go ---' && \
sed -n '1,200p' config/config.go && \
printf '%s\\n' '--- module files ---' && \
rg --files -g 'go.mod' -g 'go.sum' -g 'Makefile' && \
printf '%s\\n' '--- diff ---' && \
git diff -- config/config.go && \
printf '%s\\n' '--- test ---' && \
go test ./config"
✓ ✓
/bin/zsh -lc "sed -n '1,200p' config/config_test.go && \
git status --short && \
git diff -- config/config.go config/config_test.go go.mod go.sum"
4✓ ✓
/bin/zsh -lc 'go test ./... && \
git status --short -- config/config.go config/config_test.go go.mod go.sum && \
git diff --check -- config/config.go'
semedit/semantic_rename (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
5—semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{\n\t\tHost:       \"localhost\",\n\t\tListenPort: 8080,\n\t}\n}"
}
6—✓ ✓
/bin/zsh -lc "sed -n '1,200p' config/config.go && \
git diff -- config/config.go config/config_test.go go.mod go.sum && \
git status --short -- config/config.go config/config_test.go go.mod go.sum"
7—✓ ✓
/bin/zsh -lc "git ls-files --stage -- config/config.go config/config_test.go go.mod go.sum; git status --short --untracked-files=all | rg 'config|go\\.mod|go\\.sum' || \
true; git diff --no-ext-diff -- config/config.go; git diff --no-index /dev/null config/config.go || \
true"
8—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "config/config.go"
}
9—? ✗
/bin/zsh -lc 'make check'
10—✓ ✓
/bin/zsh -lc 'gofmt -d config/config.go && \
go test ./...'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 18 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'Makefile' -g 'AGENTS*.md' -g 'go.mod' -g 'go.sum' && \
sed -n '1,220p' config/config.go && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,220p' PROJECT_BRIEF.md; fi && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'config/config.go' -g 'Makefile' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g 'cmd/**' -g '*semantic*' | sort && \
printf '\\n--- config/config.go ---\\n' && \
sed -n '1,220p' config/config.go && \
printf '\\n--- top-level ---\\n' && \
ls -la"
2✓ ✓
/bin/zsh -lc "rg -n --glob '"'!AGENTS.override.md'"' --glob '"'!go.mod'"' --glob '"'!go.sum'"' 'Config|\\.Port|Port:' ."
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- references ---' && \
rg -n --glob '*.go' '\\b(Config|\\.Port|Port:|DefaultConfig|Addr\\()\\b' . && \
printf '%s\\n' '--- go.mod ---' && \
sed -n '1,80p' go.mod && \
printf '%s\\n' '--- source files ---' && \
rg --files -g '*.go' | sort | xargs -n1 sh -c 'echo --- \""'$0"; sed -n "1,180p" "$0"'"'"
3✓ ✓
/bin/zsh -lc "sed -n '1,220p' config/config_test.go && \
git status --short && \
git diff -- config/config.go"
semedit/semantic_rename (✓ ✓)
{
  "auto_organize_imports": false,
  "file": "config/config.go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
4✓ ✓
/bin/zsh -lc 'gofmt -w config/config.go && \
go test ./config && \
git diff -- config/config.go && \
git status --short -- config/config.go config/config_test.go go.mod go.sum'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": false,
  "file": "config/config.go",
  "placement": "file_end",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{Host: \"localhost\", ListenPort: 8080}\n}"
}
5✓ ✓
/bin/zsh -lc "sed -n '1,160p' config/config.go && \
git ls-files --stage -- config/config.go config/config_test.go go.mod go.sum && \
git status --short --untracked-files=all -- config"
semedit/semantic_organize_imports (✓ ✓)
{
  "file": "config/config.go"
}
6✓ ✓
/bin/zsh -lc 'go test ./... && \
git diff --no-ext-diff -- config/config.go config/config_test.go go.mod go.sum; git status --short --untracked-files=all -- config/config.go config/config_test.go go.mod go.sum'
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- config/config.go ---' && \
sed -n '1,180p' config/config.go && \
printf '%s\\n' '--- status ---' && \
git status --short && \
printf '%s\\n' '--- diff ---' && \
git diff -- config/config.go && \
printf '%s\\n' '--- protected-file diff check ---' && \
git diff --quiet -- go.mod go.sum; printf 'protected_diff_exit=%s\\n' \""'$?"'
7—? ✗
/bin/zsh -lc "printf '%s\\n' '--- git root ---' && \
git rev-parse --show-toplevel && \
printf '%s\\n' '--- tracked config ---' && \
git ls-files --stage -- config/config.go config/config_test.go go.mod go.sum && \
printf '%s\\n' '--- config file metadata ---' && \
stat -f '%N %z bytes %Sm' config/config.go && \
printf '%s\\n' '--- make check ---' && \
make check"
8—✓ ✓
/bin/zsh -lc "gofmt -d config/config.go && \
go test ./... && \
printf '%s\\n' '--- relevant references ---' && \
rg -n --glob '*.go' '\\b(Port|ListenPort|DefaultConfig)\\b' config && \
printf '%s\\n' '--- fixture status ---' && \
git status --short -- config go.mod go.sum"

Target: codex/gpt-5.6-luna/medium

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-09-composite-refactor
Targetcodex/gpt-5.6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_09_composite_refactor.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package config

import (
	"archive/tar"
	"fmt"
)

type Config struct {
	Host string
	Port int
}

func (c *Config) Addr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.Port)
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency48.82s79.25s+62.3%51.45s85.88s+66.9%
Process Start → First Event0.12s0.14s—0.12s0.12s—
First Event → First Tool Call6.74s16.82s—8.81s12.17s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles611+83.3%610+66.7%
Initial Load / Discovery Turns63-50.0%63-50.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)611+83.3%610+66.7%
Output Tokens16761838+9.7%15601851+18.7%
Reasoning / Thinking Tokens549508-7.5%390540+38.5%
Total Input Tokens165302469776+184.2%185889401272+115.9%
Cached Input Tokens132096435456+229.7%154368352000+128.0%
Uncached Input Tokens3320634320+3.4%3152149272+56.3%
Cost0.29880.4597+53.8%0.29330.4941+68.5%
Cached vs Uncached Token Ratio3.98:112.69:1+219.0%4.90:17.14:1+45.9%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'Makefile' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'go.mod' -g 'go.sum' | sort && \
sed -n '1,220p' config/config.go"
✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS*.md' -g 'Makefile' -g 'go.mod' | sort; sed -n '1,220p' config/config.go; if [ -f PROJECT_BRIEF.md ]; then sed -n '1,220p' PROJECT_BRIEF.md; fi"
2✓ ✓
/bin/zsh -lc "rg -n --glob '"'!AGENTS.override.md'"' 'Config\\{|\\.Port\\b|Port:' . && \
rg --files | sort"
✓ ✓
/bin/zsh -lc "rg -n --glob '"'!go.mod'"' --glob '"'!go.sum'"' 'Config|\\.Port|Port:|Host:' ."
3✓ ✓
/bin/zsh -lc "sed -n '1,240p' config/config_test.go && \
sed -n '1,160p' go.mod && \
find . -maxdepth 2 -type f -not -path './.git/*' -print"
✓ ✓
/bin/zsh -lc "sed -n '1,160p' config/config_test.go; sed -n '1,160p' go.mod; git status --short"
4✓ ✓
/bin/zsh -lc 'gofmt -w config/config.go && \
git diff --check && \
go test ./... && \
git diff -- config/config.go && \
git status --short'
semedit/semantic_rename (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
5✓ ✓
/bin/zsh -lc "git diff -- config/config.go; git status --short -- config/config.go config/config_test.go go.mod go.sum; sed -n '1,160p' config/config.go; if [ -f Makefile ]; then make check; else echo 'make check unavailable: no Makefile in fixture'; fi"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": true,
  "file": "config/config.go",
  "placement": "public_end",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{\n\t\tHost:       \"localhost\",\n\t\tListenPort: 8080,\n\t}\n}"
}
6✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
git ls-files -- config/config.go config/config_test.go go.mod go.sum && \
git diff --no-ext-diff --no-index /dev/null config/config.go | sed -n '1,120p'"
semedit/semantic_organize_imports (✓ ✓)
{
  "file": "config/config.go"
}
7—✓ ✓
/bin/zsh -lc 'git diff -- config/config.go; git status --short -- config/config.go go.mod go.sum config/config_test.go; go test ./config'
8—✓ ✓
/bin/zsh -lc "sed -n '1,160p' config/config.go; git status --short; git diff --no-ext-diff -- config/config.go"
9—✓ ✓
/bin/zsh -lc 'git show HEAD:config/config.go; git ls-files -v config/config.go; git diff --stat HEAD -- config/config.go; git status --porcelain=v2 -- config/config.go'
10—✓ ✓
/bin/zsh -lc 'git status --short --untracked-files=all --ignored -- config/config.go config/config_test.go; git check-ignore -v config/config.go config/config_test.go || \
true; git ls-files --others --exclude-standard config/config.go config/config_test.go'
11—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "config"
}
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 18 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'Makefile' -g 'AGENTS*' -g 'docs/adr/README.md' -g 'docs/research/README.md' && \
sed -n '1,220p' config/config.go"
✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'Makefile' -g 'go.mod' -g '"'!tests/**'"' -g '"'!**/*_test.go'"' | sort; sed -n '1,220p' config/config.go"
2✓ ✓
/bin/zsh -lc "rg -n \"Config|\\.Port|ListenPort|DefaultConfig|Host\" . -g '"'!AGENTS.override.md'"' -g '"'!*.sum'"' -g '"'!go.mod'"'"
✓ ✓
/bin/zsh -lc "rg -n --glob '"'!go.mod'"' --glob '"'!go.sum'"' --glob '"'!**/*_test.go'"' 'Config|\\.Port|Port:' .; rg --files | sort | head -100; git status --short"
3? ✗
/bin/zsh -lc "sed -n '1,160p' config/config_test.go && \
rg -n \"default|8080|localhost|listen\" README* docs . -g '"'!AGENTS.override.md'"' -g '"'!config/config_test.go'"' -g '"'!go.sum'"' -g '"'!go.mod'"'"
✓ ✓
/bin/zsh -lc "sed -n '1,220p' config/config_test.go; sed -n '1,160p' go.mod; find . -maxdepth 2 -type f -not -path './.git/*' -print | sort"
4? ✗
/bin/zsh -lc 'gofmt -w config/config.go && \
git diff -- config/config.go && \
make check'
semedit/semantic_rename (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
5✓ ✓
/bin/zsh -lc 'git diff --check && \
go test ./... && \
git status --short && \
git diff -- go.mod go.sum -- config/config.go'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": true,
  "file": "config/config.go",
  "placement": "after_symbol",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{Host: \"localhost\", ListenPort: 8080}\n}",
  "target_symbol": "Config"
}
6✓ ✓
/bin/zsh -lc "git diff -- config/config.go && \
git status --short -- config/config.go go.mod go.sum config/config_test.go && \
sed -n '1,120p' config/config.go"
✓ ✓
/bin/zsh -lc "sed -n '1,180p' config/config.go; git diff -- config/config.go; rg -n --glob '"'!go.mod'"' --glob '"'!go.sum'"' --glob '"'!**/*_test.go'"' '\\bPort\\b|ListenPort|DefaultConfig' ."
7—? ✗
/bin/zsh -lc 'git status --short -- config/config.go; git diff --no-index /dev/null config/config.go || \
true; make check'
8—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "config/config.go"
}
9—✓ ✓
/bin/zsh -lc 'go test ./...'
10—✓ ✓
/bin/zsh -lc "git status --short -- config/config.go config/config_test.go go.mod go.sum; sed -n '1,80p' config/config.go"

Target: codex/gpt-6-luna/high

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-09-composite-refactor
Targetcodex/gpt-6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_09_composite_refactor.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package config

import (
	"archive/tar"
	"fmt"
)

type Config struct {
	Host string
	Port int
}

func (c *Config) Addr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.Port)
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency33.35s62.00s+85.9%55.18s64.05s+16.1%
Process Start → First Event0.12s0.12s—0.13s0.12s—
First Event → First Tool Call8.86s10.46s—7.10s6.96s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles46+50.0%109-10.0%
Initial Load / Discovery Turns330%64-33.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)46+50.0%109-10.0%
Output Tokens11451584+38.3%17781506-15.3%
Reasoning / Thinking Tokens502991+97.4%872851-2.4%
Total Input Tokens99817150958+51.2%140507241110+71.6%
Cached Input Tokens88832132352+49.0%127232221696+74.2%
Uncached Input Tokens1098518606+69.4%1327519414+46.2%
Cost0.07030.1118+59.1%0.09810.1334+36.0%
Cached vs Uncached Token Ratio8.09:17.11:1-12.0%9.58:111.42:1+19.1%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 19 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'README*' | head -80 && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'docs/adr/README.md' | sort"
2✓ ✓
/bin/zsh -lc "cat config/config.go && \
rg -n 'Config\\.Port|\\.Port\\b|DefaultConfig|ListenPort' --glob '*.go' ."
✓ ✓
/bin/zsh -lc 'cat config/config.go && \
rg --files | head -80'
3✓ ✓
/bin/zsh -lc "cat config/config_test.go && \
rg -n 'Host:|ListenPort|localhost|127\\.0\\.0\\.1|:8080' --glob '*.go' ."
✓ ✓
/bin/zsh -lc 'cat config/config_test.go && \
cat go.mod'
4✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile

path = Path('config/config.go')
content = '''package config

import \"fmt\"

type Config struct {
\\tHost       string
\\tListenPort int
}

func DefaultConfig() *Config {
\\treturn &Config{
\\t\\tHost:       \"localhost\",
\\t\\tListenPort: 8080,
\\t}
}

func (c *Config) Addr() string {
\\treturn fmt.Sprintf(\"%s:%d\", c.Host, c.ListenPort)
}
'''
stat = path.stat()
with tempfile.NamedTemporaryFile('w', dir=path.parent, delete=False) as temp:
    temp.write(content)
    temp.flush()
    os.fsync(temp.fileno())
    temp_path = Path(temp.name)
os.chmod(temp_path, stat.st_mode)
os.utime(temp_path, ns=(stat.st_atime_ns, max(stat.st_mtime_ns + 1, os.stat(temp_path).st_mtime_ns)))
os.replace(temp_path, path)
PY
cat config/config.go
git diff -- config/config.go"
semedit/semantic_rename (✓ ✓)
{
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
5—semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{\n\t\tHost:       \"localhost\",\n\t\tListenPort: 8080,\n\t}\n}"
}
6—✓ ✓
/bin/zsh -lc 'cat config/config.go && \
git diff -- config/config.go && \
git status --short'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 16 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 18 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md'"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' config/config.go && \
git status --short"
2✓ ✓
/bin/zsh -lc 'cat config/config.go'
✓ ✓
/bin/zsh -lc "rg -n \"Config\\{|\\.Port\\b|DefaultConfig|ListenPort|config\\.Config|config\\.\" --glob '"'!**/*_test.go'"' ."
3✓ ✓
/bin/zsh -lc "rg -n '\\.Port\\b|\\bPort\\s*:' --glob '"'!AGENTS.override.md'"'"
? ✗
/bin/zsh -lc "rg --files -g '"'!*.sum'"' -g '"'!go.mod'"' | head -80 && \
rg -n \"default|port|host\" README* config"
4✓ ✓
/bin/zsh -lc 'git status --short'
✓ ✓
/bin/zsh -lc "sed -n '1,220p' config/config_test.go && \
sed -n '1,120p' AGENTS.override.md"
5✓ ✓
/bin/zsh -lc "rg -n 'DefaultConfig|config\\.Config|config\\.New|ListenPort|Host:' --glob '"'!AGENTS.override.md'"' --glob '"'!go.mod'"' --glob '"'!go.sum'"'"
semedit/semantic_rename (✓ ✓)
{
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
6✓ ✓
/bin/zsh -lc "cat config/config_test.go && \
rg -n '8080|localhost|127\\.0\\.0\\.1|ListenPort|Port' config --glob '*.go'"
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{Host: \"localhost\", ListenPort: 8080}\n}"
}
7✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os, tempfile, time

path = Path('config/config.go')
content = '''package config

import \"fmt\"

type Config struct {
\\tHost       string
\\tListenPort int
}

func DefaultConfig() *Config {
\\treturn &Config{Host: \"localhost\", ListenPort: 8080}
}

func (c *Config) Addr() string {
\\treturn fmt.Sprintf(\"%s:%d\", c.Host, c.ListenPort)
}
'''
fd, temporary = tempfile.mkstemp(dir=path.parent, prefix='.config.go.')
try:
    with os.fdopen(fd, 'w') as f:
        f.write(content)
        f.flush()
        os.fsync(f.fileno())
    os.replace(temporary, path)
    current = time.time()
    os.utime(path, (current, current + 1))
except Exception:
    try:
        os.unlink(temporary)
    except FileNotFoundError:
        pass
    raise
PY
gofmt -w config/config.go
"
semedit/semantic_organize_imports (✓ ✓)
{
  "file": "config/config.go"
}
8✓ ✓
/bin/zsh -lc 'cat config/config.go'
✓ ✓
/bin/zsh -lc "sed -n '1,160p' config/config.go && \
git diff -- config/config.go && \
git status --short -- config/config.go config/config_test.go go.mod go.sum"
9✓ ✓
/bin/zsh -lc 'git status --short -- config/config.go go.mod go.sum config/config_test.go'
✓ ✓
/bin/zsh -lc 'pwd; git rev-parse --show-toplevel; git ls-files --stage -- config/config.go; git check-ignore -v config/config.go || \
true; git status --short --untracked-files=all -- config/config.go'
10✓ ✓
/bin/zsh -lc 'git diff -- config/config.go'
—

Target: codex/gpt-6-luna/medium

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-09-composite-refactor
Targetcodex/gpt-6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_09_composite_refactor.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package config

import (
	"archive/tar"
	"fmt"
)

type Config struct {
	Host string
	Port int
}

func (c *Config) Addr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.Port)
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency32.09s57.16s+78.1%31.77s47.61s+49.9%
Process Start → First Event0.12s0.13s—0.14s0.13s—
First Event → First Tool Call6.64s5.08s—4.64s5.43s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles611+83.3%68+33.3%
Initial Load / Discovery Turns63-50.0%64-33.3%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)611+83.3%68+33.3%
Output Tokens8201426+73.9%956975+2.0%
Reasoning / Thinking Tokens177314+77.4%295151-48.8%
Total Input Tokens159287282604+77.4%160918194636+21.0%
Cached Input Tokens146432262912+79.5%147456177920+20.7%
Uncached Input Tokens1285519692+53.2%1346216716+24.2%
Cost0.08120.1367+68.3%0.08620.1003+16.5%
Cached vs Uncached Token Ratio11.39:113.35:1+17.2%10.95:110.64:1-2.8%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'config.go' -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g 'go.sum' -g '*.go' | head -80 && \
sed -n '1,240p' config/config.go"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'Makefile' -g 'go.mod' -g 'go.sum' | head -80"
2✓ ✓
/bin/zsh -lc "rg -n '\\bPort\\b|DefaultConfig|Config\\{' --glob '*.go' . && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'README*'"
✓ ✓
/bin/zsh -lc "cat config/config.go && \
rg -n \"DefaultConfig|\\.Port\\b|Config\\{\" --glob '"'!go.mod'"' --glob '"'!go.sum'"' . | head -100"
3✓ ✓
/bin/zsh -lc 'cat config/config_test.go && \
cat AGENTS.override.md && \
git status --short'
✓ ✓
/bin/zsh -lc 'cat config/config_test.go'
4✓ ✓
/bin/zsh -lc 'git diff -- config/config.go && \
git diff --check -- config/config.go'
semedit/semantic_rename (✓ ✗): resolve Port in config/config.go: symbol not found
{
  "file": "config/config.go",
  "language": "go",
  "symbol": "Port",
  "to": "ListenPort"
}
5✓ ✓
/bin/zsh -lc 'cat config/config.go && \
git status --short -- config/config.go && \
git rev-parse --show-toplevel'
? ✗
/bin/zsh -lc 'rg --files docs | head -30; cat docs/SUBOPTIMAL_TOOLS.md 2>/dev/null'
6✓ ✓
/bin/zsh -lc 'gofmt -w config/config.go && \
cat config/config.go'
✓ ✓
/bin/zsh -lc 'rg --files | head -60'
7—✓ ✓
/bin/zsh -lc "mkdir -p docs && \
python3 -c 'from pathlib import Path; import os, tempfile; p=Path(\"docs/SUBOPTIMAL_TOOLS.md\"); data=\"# Suboptimal Tool Behavior\\n\\n- Tool: "'`semantic_rename`'"\\n  Target: "'`config/config.go`'"\\n  Observed failure: resolving the "'`Port` struct field by the bare symbol name returned `symbol not found`.'"\\n  Workaround: use a narrow source edit for the field declaration and its receiver reference.\\n  Root cause: the Go rename tool did not resolve this field through the supplied symbol identifier.\\n\"; fd, name=tempfile.mkstemp(dir=str(p.parent), prefix=\".SUBOPTIMAL_TOOLS.\"); f=os.fdopen(fd,\"w\"); f.write(data); f.flush(); os.fsync(f.fileno()); f.close(); os.replace(name,p); d=os.open(str(p.parent),os.O_RDONLY); os.fsync(d); os.close(d)'"
8—semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{\n\t\tHost:       \"localhost\",\n\t\tListenPort: 8080,\n\t}\n}"
}
9—✓ ✓
/bin/zsh -lc 'cat config/config.go'
10—✓ ✓
/bin/zsh -lc "python3 -c 'from pathlib import Path; import os, tempfile; p=Path(\"config/config.go\"); s=p.read_text(); s=s.replace(\"\\tPort int\", \"\\tListenPort int\").replace(\"c.Host, c.Port\", \"c.Host, c.ListenPort\"); fd, name=tempfile.mkstemp(dir=str(p.parent), prefix=\".config.go.\"); f=os.fdopen(fd,\"w\"); f.write(s); f.flush(); os.fsync(f.fileno()); f.close(); os.replace(name,p); d=os.open(str(p.parent),os.O_RDONLY); os.fsync(d); os.close(d)' && \
cat config/config.go && \
git status --short"
11—✓ ✓
/bin/zsh -lc 'gofmt -w config/config.go && \
cat config/config.go && \
git status --short -- config/config.go docs/SUBOPTIMAL_TOOLS.md go.mod go.sum'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 21 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'README*' | head -80 && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'docs/**' | head -80 && \
git status --short"
2✓ ✓
/bin/zsh -lc "cat config/config.go && \
rg -n '\\.Port\\b|Port:' --glob '*.go'"
✓ ✓
/bin/zsh -lc "cat config/config.go && \
rg -n \"Config\\.Port|\\.Port\\b|DefaultConfig|ListenPort\" --glob '*.go'"
3✓ ✓
/bin/zsh -lc "rg -n 'DefaultConfig|ListenPort|default.*(port|host)|localhost|8080' --glob '"'!*.sum'"'"
✓ ✓
/bin/zsh -lc 'rg --files | head -80; cat AGENTS.override.md'
4✓ ✓
/bin/zsh -lc 'cat config/config_test.go && \
rg --files | head -60'
✓ ✓
/bin/zsh -lc 'cat config/config_test.go'
5✓ ✓
/bin/zsh -lc 'gofmt -w config/config.go && \
git diff -- config/config.go && \
git status --short -- config/config.go go.mod go.sum'
semedit/semantic_rename (✓ ✓)
{
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
6✓ ✓
/bin/zsh -lc 'cat config/config.go && \
git rev-parse --show-toplevel && \
git status --short --untracked-files=all -- config/config.go go.mod go.sum'
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{\n\t\tHost:       \"localhost\",\n\t\tListenPort: 8080,\n\t}\n}"
}
7—✓ ✓
/bin/zsh -lc 'cat config/config.go && \
git status --short -- config/config.go config/config_test.go go.mod go.sum'
8—semedit/semantic_organize_imports (✓ ✓)
{
  "file": "config/config.go"
}

Target: codex/gpt-6-luna/xhigh

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-09-composite-refactor
Targetcodex/gpt-6-luna/xhigh
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_09_composite_refactor.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

In config/config.go: rename Config.Port to Config.ListenPort, insert helper function DefaultConfig() *Config returning default values, and clean up unused imports. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
package config

import (
	"archive/tar"
	"fmt"
)

type Config struct {
	Host string
	Port int
}

func (c *Config) Addr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.Port)
}
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency119.16s70.98s-40.4%67.92s66.99s-1.4%
Process Start → First Event0.12s0.12s—0.13s0.12s—
First Event → First Tool Call11.88s7.83s—10.36s10.75s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles67+16.7%48+100.0%
Initial Load / Discovery Turns34+33.3%25+150.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)67+16.7%48+100.0%
Output Tokens34262629-23.3%30252320-23.3%
Reasoning / Thinking Tokens24052077-13.6%19911643-17.5%
Total Input Tokens143511223860+56.0%104062166919+60.4%
Cached Input Tokens127232200704+57.7%90880148736+63.7%
Uncached Input Tokens1627923156+42.2%1318218183+37.9%
Cost0.14540.1669+14.8%0.11840.1322+11.7%
Cached vs Uncached Token Ratio7.82:18.67:1+10.9%6.89:18.18:1+18.6%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 20 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File config/config.go modified (15 lines -> 18 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g '*.go' | head -100"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' config/config.go && \
git status --short"
2✓ ✓
/bin/zsh -lc "cat config/config.go && \
rg -n '\\bPort\\b|DefaultConfig|Config\\{' --glob '*.go' ."
✓ ✓
/bin/zsh -lc "rg -n '\\bPort\\b|Config\\{' --glob '*.go' ."
3✓ ✓
/bin/zsh -lc 'cat config/config_test.go && \
rg --files'
✓ ✓
/bin/zsh -lc "rg -n 'DefaultConfig|ListenPort|Config\\{|Host:|Port:' --glob '*.go' --glob '*.md' .; rg --files config"
4✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import tempfile
import time

path = Path('config/config.go')
old_stat = path.stat()
content = '''// Package config centralizes the host and listen port used to build the server address.
package config

import \"fmt\"

type Config struct {
\\tHost       string
\\tListenPort int
}

func DefaultConfig() *Config {
\\treturn &Config{
\\t\\tHost:       \"localhost\",
\\t\\tListenPort: 8080,
\\t}
}

func (c *Config) Addr() string {
\\treturn fmt.Sprintf(\"%s:%d\", c.Host, c.ListenPort)
}
'''
fd, temp_name = tempfile.mkstemp(prefix='.config.go.', dir=path.parent)
try:
    with os.fdopen(fd, 'w') as temp_file:
        temp_file.write(content)
        temp_file.flush()
        new_mtime_ns = max(time.time_ns(), old_stat.st_mtime_ns + 1_000_000)
        os.utime(temp_file.fileno(), ns=(old_stat.st_atime_ns, new_mtime_ns))
        os.fsync(temp_file.fileno())
    os.chmod(temp_name, old_stat.st_mode)
    os.replace(temp_name, path)
    directory_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(directory_fd)
    finally:
        os.close(directory_fd)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY
gofmt -d config/config.go
git diff -- config/config.go"
✓ ✓
/bin/zsh -lc 'cat config/config_test.go'
5✓ ✓
/bin/zsh -lc 'cat config/config.go && \
git status --short && \
git diff -- config/config.go'
semedit/semantic_rename (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
6✓ ✓
/bin/zsh -lc "rg -n '\\.Port\\b|\\bPort:' --glob '*.go' .; test -z \""'$(gofmt -d config/config.go)"'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": true,
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{Host: \"localhost\", ListenPort: 8080}\n}"
}
7—✓ ✓
/bin/zsh -lc 'cat config/config.go && \
git diff -- config/config.go go.mod go.sum'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 19 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File config/config.go modified (15 lines -> 21 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'config.go' -g '*.go' | head -80 && \
git status --short && \
sed -n '1,240p' config/config.go && \
rg -n '\\bPort\\b|\\.Port\\b' --glob '*.go' --glob '"'!**/*_test.go'"' ."
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'config/config.go' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g 'Makefile'"
2✓ ✓
/bin/zsh -lc "rg -n 'config\\.Config|Config\\{|DefaultConfig|\\bHost\\b|\\bPort\\b' --glob '*.go' --glob '"'!**/*_test.go'"' . && \
sed -n '1,220p' config/config_test.go && \
rg --files -g 'README*' -g 'PROJECT_BRIEF.md' -g 'go.mod' -g '*.yaml' -g '*.yml' | head -80"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' config/config.go"
3✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import stat
import tempfile
import time
from pathlib import Path

path = Path('config/config.go')
old_stat = path.stat()
content = '''package config

import \"fmt\"

type Config struct {
\\tHost       string
\\tListenPort int
}

func DefaultConfig() *Config {
\\treturn &Config{
\\t\\tHost:       \"localhost\",
\\t\\tListenPort: 8080,
\\t}
}

func (c *Config) Addr() string {
\\treturn fmt.Sprintf(\"%s:%d\", c.Host, c.ListenPort)
}
'''
fd, temp_name = tempfile.mkstemp(prefix='.config.go.', dir=path.parent)
try:
    with os.fdopen(fd, 'w', encoding='utf-8') as temp_file:
        temp_file.write(content)
        temp_file.flush()
        os.fsync(temp_file.fileno())
    os.chmod(temp_name, stat.S_IMODE(old_stat.st_mode))
    timestamp = max(time.time_ns(), old_stat.st_mtime_ns + 1_000_000_000)
    os.utime(temp_name, ns=(timestamp, timestamp))
    os.replace(temp_name, path)
    directory_fd = os.open(path.parent, os.O_RDONLY)
    try:
        os.fsync(directory_fd)
    finally:
        os.close(directory_fd)
except BaseException:
    try:
        os.unlink(temp_name)
    except FileNotFoundError:
        pass
    raise
PY
gofmt -d config/config.go
git diff -- config/config.go"
✓ ✓
/bin/zsh -lc "rg -n --glob '*.go' 'Config\\{|\\.Port\\b|ListenPort|DefaultConfig\\(' ."
4✓ ✓
/bin/zsh -lc "sed -n '1,180p' config/config.go && \
rg -n '\\bPort\\b|\\.Port\\b' --glob '*.go' . || \
true && \
gofmt -d config/config.go"
✓ ✓
/bin/zsh -lc "rg --files | sed -n '1,120p'"
5—✓ ✓
/bin/zsh -lc "sed -n '1,160p' config/config_test.go && \
rg -n --glob '*.go' 'config\\.Config|config\\.DefaultConfig|\\.Addr\\(' ."
6—semedit/semantic_rename (✓ ✓)
{
  "file": "config/config.go",
  "language": "go",
  "symbol": "Config.Port",
  "to": "ListenPort"
}
7—semedit/semantic_insert_function (✓ ✓)
{
  "file": "config/config.go",
  "placement": "public_start",
  "source": "func DefaultConfig() *Config {\n\treturn \u0026Config{\n\t\tHost:       \"localhost\",\n\t\tListenPort: 8080,\n\t}\n}"
}
8—✓ ✓
/bin/zsh -lc "git status --short && \
git diff -- config/config.go && \
sed -n '1,120p' config/config.go"

Test case: task-11-mixed-sink-api-migration

Target: codex/gpt-5.6-luna/high

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-5.6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)⚠ MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency115.42s123.12sN/A162.74s274.95s+69.0%
Process Start → First Event0.12s0.12s—0.12s0.12s—
First Event → First Tool Call7.63s9.46s—9.04s8.71s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns11N/A110%
Internal Tool Cycles810N/A1025+150.0%
Initial Load / Discovery Turns11N/A220%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)810N/A1025+150.0%
Output Tokens52195378N/A71928881+23.5%
Reasoning / Thinking Tokens32923332N/A38755073+30.9%
Total Input Tokens233129285581N/A384319856359+122.8%
Cached Input Tokens207360240640N/A348672766976+120.0%
Uncached Input Tokens2576944941N/A3564789383+150.7%
Cost0.48790.6063N/A0.68461.2490+82.5%
Cached vs Uncached Token Ratio8.05:15.35:1N/A9.78:18.58:1-12.3%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/AFAIL—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*AGENTS.override.md'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sed -n '1,160p'"
✓ ✓
/bin/zsh -lc "pwd; rg --files -g '"'!*_test.go'"' -g '"'!AGENTS.override.md'"' | sort; printf '\\n--- docs ---\\n'; rg --files -g 'PROJECT_BRIEF.md' -g 'docs/**' -g 'AGENTS.md' | sort"
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' docs/audit-sinks.md && \
sed -n '1,260p' audit/event.go && \
sed -n '1,260p' audit/normalize.go && \
sed -n '1,260p' audit/sink.go && \
sed -n '1,280p' service/dispatch.go && \
sed -n '1,240p' audit/summary.go && \
sed -n '1,220p' legacy/export.go && \
sed -n '1,220p' metrics/writer.go"
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- docs/audit-sinks.md ---'; sed -n '1,240p' docs/audit-sinks.md; printf '%s\\n' '--- source ---'; for f in audit/event.go audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go metrics/writer.go legacy/export.go cmd/migrate/main.go; do echo \"--- "'$f ---"; sed -n '"'1,260p' \""'$f"; done'
3✓ ✓
/bin/zsh -lc "sed -n '1,280p' audit/event_test.go && \
sed -n '1,260p' audit/summary_test.go && \
sed -n '1,300p' service/dispatch_test.go && \
sed -n '1,240p' legacy/export_test.go && \
sed -n '1,240p' metrics/writer_test.go && \
git status --short && \
git diff -- audit service legacy metrics docs"
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- tests ---'; for f in "'$(rg --files -g '"'*_test.go' | sort); do echo \"--- "'$f ---"; sed -n '"'1,300p' \""'$f"; done; printf '"'%s\\n' '--- repo files ---'; rg --files -g 'Makefile' -g 'README*' -g '.golangci*' -g 'scripts/**' -g '*.sh' | sort; printf '%s\\n' '--- git status ---'; git status --short"
4✓ ✓
/bin/zsh -lc "sed -n '1,260p' cmd/migrate/main.go && \
find . -maxdepth 3 -type f -not -path './.git/*' -print | sort && \
git ls-files --stage -- service audit legacy metrics docs cmd go.mod go.sum"
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- module ---'; sed -n '1,120p' go.mod; printf '%s\\n' '--- all source references ---'; rg -n \"Normalize|normalize|Write\\(|DispatchAll|Record\\(|Classify|probe|health|MemorySink|Sink\" . -g '"'!AGENTS.override.md'"'; printf '%s\\n' '--- command files ---'; find . -maxdepth 2 -type f -not -path './.git/*' -print | sort"
5? ✗
/bin/zsh -lc 'make check'
✓ ✓
/bin/zsh -lc 'git log --oneline --all --decorate -8; git branch --show-current; git diff -- audit service metrics legacy go.mod go.sum'
6✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
go test ./...'
? ✗
/bin/zsh -lc 'git log --oneline --all -- audit/normalize.go audit/sink.go service/dispatch.go | head -20; git show HEAD:audit/normalize.go; git show HEAD:audit/sink.go'
7✓ ✓
/bin/zsh -lc "git status --short --untracked-files=all -- . && \
git diff --no-ext-diff -- go.mod go.sum && \
sed -n '1,180p' audit/normalize.go && \
sed -n '1,220p' audit/sink.go && \
sed -n '1,180p' audit/summary.go && \
sed -n '1,220p' service/dispatch.go"
✓ ✓
/bin/zsh -lc 'git status --short --untracked-files=all -- .; git ls-files -- . | head -50; ls -la'
8✓ ✓
/bin/zsh -lc 'git rev-parse --show-toplevel && \
git status --short --untracked-files=all -- audit service legacy metrics docs cmd go.mod go.sum && \
git diff --stat -- audit service legacy metrics docs cmd go.mod go.sum'
? ✗
/bin/zsh -lc 'make check'
9—✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/summary.go
go test ./...'
10—✓ ✓
/bin/zsh -lc "go vet ./...
make check
printf '%s\\n' '--- changed implementation ---'
sed -n '1,120p' audit/normalize.go
sed -n '1,120p' audit/sink.go
sed -n '1,80p' audit/summary.go
printf '%s\\n' '--- protected files present ---'
stat -f '%N %z bytes' go.mod audit/event_test.go service/dispatch_test.go metrics/writer_test.go legacy/export_test.go"
⚠ Why no semantic edit tool was used
I did not discover any callable `semantic_*` tools from the available semedit MCP server in this environment. I therefore used ordinary editing for the small, localized change.
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!AGENTS.override.md'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort && \
printf '\\n--- status ---\\n' && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS*.md' -g '"'!AGENTS.override.md'"' -g '*.go' -g 'Makefile' -g 'docs/**' | sed -n '1,160p'"
2✓ ✓
/bin/zsh -lc "ls -la && \
printf '\\n--- docs ---\\n' && \
sed -n '1,240p' docs/audit-sinks.md && \
printf '\\n--- event.go ---\\n' && \
sed -n '1,240p' audit/event.go && \
printf '\\n--- normalize.go ---\\n' && \
sed -n '1,240p' audit/normalize.go && \
printf '\\n--- fanout.go ---\\n' && \
sed -n '1,280p' audit/fanout.go && \
printf '\\n--- sink.go ---\\n' && \
sed -n '1,240p' audit/sink.go"
✓ ✓
/bin/zsh -lc "git status --short && \
sed -n '1,240p' audit/event.go && \
sed -n '1,260p' audit/normalize.go && \
sed -n '1,280p' audit/fanout.go && \
sed -n '1,240p' audit/sink.go && \
sed -n '1,240p' audit/transaction.go && \
sed -n '1,220p' docs/audit-sinks.md"
3✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- all Go sources ---' && \
rg -n \"audit|Event|Kind|Probe|probe|Write\\(|Fanout|metrics|legacy|Normalize|normalize\" --glob '*.go' --glob '"'!go.mod'"' --glob '"'!go.sum'"' . && \
printf '%s\\n' '--- audit tests ---' && \
sed -n '1,260p' audit/event_test.go && \
sed -n '1,300p' audit/summary.go && \
sed -n '1,300p' audit/summary_test.go && \
sed -n '1,300p' audit/transaction.go && \
printf '%s\\n' '--- service dispatch ---' && \
sed -n '1,320p' service/dispatch.go && \
sed -n '1,360p' service/dispatch_test.go && \
printf '%s\\n' '--- metrics and legacy ---' && \
sed -n '1,280p' metrics/metrics.go && \
sed -n '1,320p' metrics/writer.go && \
sed -n '1,280p' legacy/export.go"
✓ ✓
/bin/zsh -lc "sed -n '1,280p' audit/event_test.go && \
sed -n '1,280p' audit/summary.go && \
sed -n '1,280p' audit/summary_test.go && \
sed -n '1,260p' audit/transaction.go && \
sed -n '1,260p' metrics/writer.go && \
sed -n '1,220p' metrics/metrics.go && \
sed -n '1,280p' legacy/export.go && \
sed -n '1,280p' service/dispatch.go && \
sed -n '1,260p' service/replay.go && \
rg -n \"audit|Event|Probe|probe|Write\\(\" --glob '*.go' --glob '"'!**/*_test.go'"' ."
4✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- remaining sources ---' && \
for f in api/router.go auth/auth.go cache/cache.go config/config.go db/db.go health/health.go journal/file.go logging/logging.go models/models.go service/replay.go utils/utils.go; do echo \"--- "'$f"; sed -n '"'1,260p' \""'$f"; done && \
printf '"'%s\\n' '--- module ---' && \
sed -n '1,80p' go.mod && \
printf '%s\\n' '--- git diff in fixture ---' && \
git diff -- . ':(exclude)go.mod' ':(exclude)go.sum' ':(exclude)AGENTS.override.md'"
✓ ✓
/bin/zsh -lc "sed -n '1,220p' journal/file.go && \
sed -n '1,260p' api/router.go && \
sed -n '1,240p' db/db.go && \
sed -n '1,240p' logging/logging.go && \
sed -n '1,240p' health/health.go && \
sed -n '1,240p' cache/cache.go && \
sed -n '1,240p' models/models.go && \
rg --files -g 'go.mod' -g 'go.sum' -g 'Makefile' -g 'README*' -g '*brief*' -g 'AGENTS*' -g 'docs/**' | sort"
5✓ ✓
/bin/zsh -lc "find . -maxdepth 2 -type f -not -name AGENTS.override.md -not -name go.mod -not -name go.sum -print | sort && \
printf '\\n--- available checks ---\\n' && \
find . -maxdepth 2 -type f \\( -name 'Makefile' -o -name 'Taskfile.yml' -o -name 'README*' -o -name 'PROJECT_BRIEF.md' \\) -print"
✓ ✓
/bin/zsh -lc "git log --oneline --all --decorate -12 && \
git diff -- audit go.mod go.sum service journal metrics legacy docs/audit-sinks.md && \
git show HEAD:go.mod && \
find . -maxdepth 2 -type f -not -path './.git/*' -print | sort"
6✓ ✓
/bin/zsh -lc "gofmt -w audit/normalize.go audit/summary.go audit/sink.go audit/fanout.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go && \
printf '%s\\n' '--- diff stat ---' && \
git diff --stat -- audit journal service && \
printf '%s\\n' '--- diff ---' && \
git diff -- audit journal service && \
printf '%s\\n' '--- protected file status ---' && \
git status --short -- go.mod go.sum AGENTS.override.md"
✓ ✓
/bin/zsh -lc "sed -n '1,300p' service/dispatch_test.go && \
sed -n '1,260p' legacy/export_test.go && \
sed -n '1,220p' metrics/writer_test.go && \
go env GOMOD && \
go test ./..."
7✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
printf '%s\\n' '--- tracked fixture files ---' && \
git ls-files -- audit journal service | head -100 && \
printf '%s\\n' '--- source snapshots ---' && \
sed -n '1,120p' audit/normalize.go && \
sed -n '1,120p' audit/summary.go && \
printf '%s\\n' '--- status scoped ---' && \
git status --short --untracked-files=all -- audit journal service"
semedit/semantic_insert_function (✓ ✗): validate function snippet: multiple declarations found in snippet: expected single function declaration, found 2 declarations
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}\n\nfunc NormalizeEvent(event Event) Event {\n\tevent.Kind = NormalizeKind(event.Kind)\n\treturn event\n}"
}
8✓ ✓
/bin/zsh -lc 'go test ./...'
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
9✓ ✓
/bin/zsh -lc "gofmt -w audit/transaction.go && \
go test ./... && \
printf '%s\\n' '--- protected files unchanged by mtime check ---' && \
stat -f '%N %m' go.mod go.sum 2>/dev/null || \
true && \
printf '%s\\n' '--- changed source mtimes ---' && \
stat -f '%N %m' audit/normalize.go audit/summary.go audit/sink.go audit/fanout.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go"
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeEvent(event Event) Event {\n\tevent.Kind = NormalizeKind(event.Kind)\n\treturn event\n}"
}
10✓ ✓
/bin/zsh -lc 'go vet ./...'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "kind = NormalizeKind(kind)\n\tswitch kind {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
11—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = NormalizeEvent(event)\n\tm.Events = append(m.Events, event)\n\treturn nil",
  "file": "audit/sink.go",
  "symbol": "(*MemorySink).Write"
}
12—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = NormalizeEvent(event)\n\tif err := f.First.Write(event); err != nil {\n\t\treturn err\n\t}\n\treturn f.Second.Write(event)",
  "file": "audit/fanout.go",
  "symbol": "FanoutSink.Write"
}
13—semedit/semantic_replace_body (✓ ✓)
{
  "body": "for _, event := range b.queue {\n\t\tif err := b.Sink.Write(NormalizeEvent(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "audit/transaction.go",
  "symbol": "(*BufferedSink).Commit"
}
14—semedit/semantic_replace_body (✓ ✓)
{
  "body": "return d.sink.Write(audit.NormalizeEvent(event))",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
15—semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\n\tfor _, event := range events {\n\t\tif err := writeEvent(sink, audit.NormalizeEvent(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
16—semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\n\tfor _, event := range events {\n\t\tif err := writeEvent(sink, audit.NormalizeEvent(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/replay.go",
  "symbol": "Replay"
}
17—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = audit.NormalizeEvent(event)\n\tj.Entries = append(j.Entries, event)\n\treturn nil",
  "file": "journal/file.go",
  "symbol": "(*JournalSink).Write"
}
18—semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": false,
  "file": "audit/transaction.go",
  "placement": "file_end",
  "source": "func (b *BufferedSink) Write(event Event) error {\n\tb.queue = append(b.queue, NormalizeEvent(event))\n\treturn nil\n}"
}
19—semedit/semantic_verify (✓ ✓)
{
  "path": "."
}
20—? ✗
/bin/zsh -lc 'make check'
21—✓ ✓
/bin/zsh -lc 'gofmt -d audit journal service && \
git diff --check && \
git diff --name-only -- go.mod go.sum && \
go test ./...'
22—✓ ✓
/bin/zsh -lc "git diff -- audit/normalize.go audit/summary.go audit/sink.go audit/fanout.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go docs/SUBOPTIMAL_TOOLS.md && \
printf '\\nChanged files in fixture:\\n' && \
git status --short -- audit journal service docs go.mod go.sum && \
printf '\\nProtected-file diff check:\\n' && \
git diff --quiet -- go.mod go.sum; printf 'exit=%s\\n' \""'$?"'
23—✓ ✓
/bin/zsh -lc "sed -n '1,220p' audit/normalize.go; sed -n '1,160p' audit/summary.go; sed -n '1,180p' audit/transaction.go; sed -n '1,140p' service/dispatch.go; git status --short --untracked-files=all | sed -n '1,120p'; git rev-parse --show-toplevel; git ls-files audit/normalize.go audit/summary.go"
24—✓ ✓
/bin/zsh -lc "git check-ignore -v audit/normalize.go docs/SUBOPTIMAL_TOOLS.md || \
true; git ls-files --error-unmatch audit/normalize.go || \
true; git status --short --untracked-files=all -- .scratch/benchmarks/run_codex_semedit_large-default_task-11-mixed-sink-api-migration_1790264881860244000 | sed -n '1,80p'; git diff --no-index /dev/null audit/normalize.go | sed -n '1,120p'"
25—✓ ✓
/bin/zsh -lc 'go vet ./... && \
git diff --check && \
test ! -e go.sum && \
printf '"'go.sum absent and untouched\\n' && \
printf 'production files:\\n' && \
for f in audit/normalize.go audit/summary.go audit/sink.go audit/fanout.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go; do test -f \""'$f" && \
printf '"'%s\\n' \""'$f"; done && \
printf '"'test files unchanged by task operations\\n'"

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-5.6-luna/high
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency163.51s178.96s+9.4%197.79s247.02s+24.9%
Process Start → First Event0.12s0.13s—0.12s0.12s—
First Event → First Tool Call19.14s17.10s—16.21s19.07s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%110%
Internal Tool Cycles1917-10.5%1122+100.0%
Initial Load / Discovery Turns31-66.7%21-50.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)1917-10.5%1122+100.0%
Output Tokens69335637-18.7%88237677-13.0%
Reasoning / Thinking Tokens33643222-4.2%45004546+1.0%
Total Input Tokens482477792585+64.3%5715821119409+95.8%
Cached Input Tokens418304745216+78.2%5253121063936+102.5%
Uncached Input Tokens6417347369-26.2%4627055473+19.9%
Cost0.83890.8752+4.3%0.89371.1760+31.6%
Cached vs Uncached Token Ratio6.52:115.73:1+141.4%11.35:119.18:1+68.9%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS*.md' -g 'go.mod' -g 'go.sum' -g 'Makefile' -g 'docs/**' -g '*.go' -g '*.txtar' | sort"
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- files ---'; rg --files -g '"'!tests/**'"' -g '"'!testdata/**'"' | sort | sed -n '1,160p'; printf '%s\\n' '--- brief ---'; if test -f PROJECT_BRIEF.md; then sed -n '1,240p' PROJECT_BRIEF.md; fi; printf '%s\\n' '--- status ---'; git status --short"
2✓ ✓
/bin/zsh -lc 'git status --short && \
git diff --stat'
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- docs/audit-sinks.md ---'; sed -n '1,260p' docs/audit-sinks.md; printf '%s\\n' '--- audit files ---'; for f in audit/event.go audit/normalize.go audit/sink.go audit/summary.go; do printf '\\n### %s\\n' \""'$f"; sed -n '"'1,260p' \""'$f"; done; printf '"'%s\\n' '--- consumers ---'; for f in service/dispatch.go cmd/migrate/main.go metrics/writer.go legacy/export.go; do printf '\\n### %s\\n' \""'$f"; sed -n '"'1,260p' \""'$f"; done'
3✓ ✓
/bin/zsh -lc "sed -n '1,240p' docs/audit-sinks.md && \
sed -n '1,240p' audit/event.go && \
sed -n '1,240p' audit/normalize.go && \
sed -n '1,260p' audit/sink.go && \
sed -n '1,260p' audit/summary.go"
✓ ✓
/bin/zsh -lc "for f in audit/event_test.go audit/summary_test.go service/dispatch_test.go metrics/writer_test.go legacy/export_test.go; do printf '\\n### %s\\n' \""'$f"; sed -n '"'1,320p' \""'$f"; done; printf '"'\\n--- module ---\\n'; sed -n '1,120p' go.mod; printf '\\n--- symbols ---\\n'; rg -n \"Record|DispatchAll|Write\\(|Classify|probe|health|Kind|normalize|normalize\" --glob '*.go' --glob '"'!**/*_test.go'"'"
4✓ ✓
/bin/zsh -lc "sed -n '1,260p' service/dispatch.go && \
sed -n '1,260p' metrics/writer.go && \
sed -n '1,260p' legacy/export.go && \
sed -n '1,240p' cmd/migrate/main.go && \
sed -n '1,160p' go.mod"
cua_repl/js (✓ ✓)
{
  "code": "await cua.getState()",
  "title": "Inspect connected tool surfaces"
}
5✓ ✓
/bin/zsh -lc "sed -n '1,260p' audit/event_test.go && \
sed -n '1,300p' audit/summary_test.go && \
sed -n '1,300p' service/dispatch_test.go && \
sed -n '1,260p' metrics/writer_test.go && \
sed -n '1,240p' legacy/export_test.go"
cua_repl/js (✓ ✓)
{
  "code": "await cua.getState({emit:false})",
  "title": "Confirm workspace tool surface"
}
6✓ ✓
/bin/zsh -lc "rg --files -g 'Makefile' -g '*.yaml' -g '*.yml' -g '*.sh' -g 'README*' -g 'PROJECT_BRIEF.md' | sort | xargs -r -n1 sh -c 'echo --- \""'$0"; sed -n "1,220p" "$0"'"'"
semedit/semantic_lookup (✓ ✓)
{
  "file": "audit/sink.go",
  "language": "go",
  "symbol": "(*MemorySink).Write"
}
7✓ ✓
/bin/zsh -lc "rg -n --hidden --glob '"'!AGENTS.override.md'"' --glob '"'!go.mod'"' --glob '"'!go.sum'"' 'Kind|Classify|\\.Write\\(|DispatchAll|Record\\(' ."
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- fixture metadata ---'; rg --files -g '.agents/**' -g '.codex/**' -g '*.md' | sort; printf '%s\\n' '--- all source ---'; rg -n \""'^func |''^type |''^var |''^const " --glob '"'*.go' --glob '"'!**/*_test.go'"'"
8✓ ✓
/bin/zsh -lc 'git log --oneline --all --decorate -8 -- . && \
git diff -- audit/event.go audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go metrics/writer.go legacy/export.go'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
9? ✗
/bin/zsh -lc 'make check'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\nreturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
10✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "writeEvent := audit.Sink.Write\nfor _, event := range events {\n\tevent.Kind = audit.NormalizeKind(event.Kind)\n\tif err := writeEvent(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
11✓ ✓
/bin/zsh -lc 'git status --short -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go audit/event_test.go audit/summary_test.go service/dispatch_test.go metrics/writer.go legacy/export.go go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event.Kind = NormalizeKind(event.Kind)\nm.Events = append(m.Events, event)\nreturn nil",
  "file": "audit/sink.go",
  "symbol": "(*MemorySink).Write"
}
12✓ ✓
/bin/zsh -lc 'git diff --check -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
git diff -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "switch NormalizeKind(kind) {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
13✓ ✓
/bin/zsh -lc 'go test ./...'
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- diff ---'; git diff -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go; printf '%s\\n' '--- protected file diff ---'; git diff -- go.mod go.sum; printf '%s\\n' '--- changed files ---'; git status --short -- audit service metrics legacy cmd go.mod go.sum; printf '%s\\n' '--- top-level ---'; ls -la"
14✓ ✓
/bin/zsh -lc "sed -n '1,200p' audit/normalize.go && \
sed -n '1,120p' audit/sink.go && \
sed -n '1,120p' audit/summary.go && \
sed -n '1,140p' service/dispatch.go"
✓ ✓
/bin/zsh -lc "for f in audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go; do printf '\\n### %s\\n' \""'$f"; sed -n '"'1,140p' \""'$f"; done; printf '"'\\n--- git root ---\\n'; git rev-parse --show-toplevel; git status --short --untracked-files=all -- ."
15✓ ✓
/bin/zsh -lc 'git rev-parse --show-toplevel && \
git ls-files --stage -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
git check-ignore -v audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go || \
true'
? ✗
/bin/zsh -lc 'make check'
16✓ ✓
/bin/zsh -lc 'git diff --no-ext-diff --no-index /dev/null audit/normalize.go; git diff --stat --no-ext-diff'
✓ ✓
/bin/zsh -lc 'gofmt -d audit service cmd/migrate metrics legacy; go test ./...'
17✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go'
semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
18✓ ✓
/bin/zsh -lc 'go vet ./...'
—
19✓ ✓
/bin/zsh -lc 'go test ./...'
—
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g 'README*' -g 'go.mod' -g 'go.sum' -g '*.go' -g '*.md' | sort | sed -n '1,240p'"
✓ ✓
/bin/zsh -lc "rg --files -g '"'!AGENTS.override.md'"' | sort && \
echo '--- status ---' && \
git status --short && \
echo '--- docs candidates ---' && \
rg --files -g 'PROJECT_BRIEF.md' -g 'Makefile' -g 'docs/**' -g '*.go' | sort"
2✓ ✓
/bin/zsh -lc "sed -n '1,260p' AGENTS.override.md && \
sed -n '1,260p' docs/audit-sinks.md && \
sed -n '1,220p' audit/event.go && \
sed -n '1,260p' audit/normalize.go && \
sed -n '1,260p' audit/fanout.go && \
sed -n '1,220p' audit/sink.go && \
sed -n '1,240p' audit/transaction.go"
✓ ✓
/bin/zsh -lc 'for f in docs/audit-sinks.md audit/event.go audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go service/replay.go metrics/metrics.go metrics/writer.go legacy/export.go; do echo "--- $f ---"; sed -n '"'1,260p' \""'$f"; done'
3✓ ✓
/bin/zsh -lc 'for f in api/router.go auth/auth.go cache/cache.go cmd/migrate/main.go cmd/replay/main.go config/config.go db/db.go health/health.go journal/file.go legacy/export.go logging/logging.go metrics/metrics.go metrics/writer.go models/models.go service/dispatch.go service/replay.go utils/utils.go audit/summary.go; do echo "--- $f"; sed -n '"'1,280p' \""'$f"; done'
✓ ✓
/bin/zsh -lc 'for f in audit/*_test.go service/*_test.go metrics/*_test.go legacy/*_test.go api/*_test.go; do echo "--- $f ---"; sed -n '"'1,280p' \""'$f"; done && \
echo '"'--- go.mod ---' && \
sed -n '1,120p' go.mod && \
echo '--- Makefile? ---' && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; else echo '(none)'; fi"
4✓ ✓
/bin/zsh -lc 'for f in audit/*_test.go service/*_test.go metrics/*_test.go legacy/*_test.go api/*_test.go; do echo "--- $f"; sed -n '"'1,300p' \""'$f"; done; echo '"'--- git status'; git status --short; echo '--- git diff'; git diff -- . ':(exclude)go.mod' ':(exclude)go.sum'"
semedit/semantic_lookup (✓ ✗): resolve Normalize in audit/normalize.go: symbol not found
{
  "file": "audit/normalize.go",
  "language": "go",
  "symbol": "Normalize"
}
5✓ ✓
/bin/zsh -lc "sed -n '1,160p' go.mod; rg -n \"audit|probe|normalize|Sink|Record|Replay|DispatchAll|Classify\" --glob '*.go' --glob '*.md' ."
✓ ✓
/bin/zsh -lc "rg -n \"probe|Normalize|normalize|Classify|Sink|Record|DispatchAll|Replay|audit\" . -g '"'!AGENTS.override.md'"'"
6✓ ✓
/bin/zsh -lc "git log --oneline --all -- audit service journal docs/audit-sinks.md | sed -n '1,80p'; git branch --all --no-color | sed -n '1,80p'; find . -maxdepth 3 -type f -not -path './.git/*' -print | sort"
✓ ✓
/bin/zsh -lc 'for f in journal/file.go api/router.go cmd/migrate/main.go cmd/replay/main.go; do echo "--- $f ---"; sed -n '"'1,220p' \""'$f"; done'
7✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/transaction.go; sed -n '1,80p' audit/normalize.go; git diff -- audit journal service"
semedit/semantic_lookup (✓ ✓)
{
  "file": "audit/sink.go",
  "language": "go",
  "symbol": "(*MemorySink).Write"
}
8✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go journal/file.go service/dispatch.go service/replay.go && \
go test ./...'
semedit/semantic_insert_declaration (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}",
  "visibility": "public"
}
9✓ ✓
/bin/zsh -lc 'git diff -- audit journal service metrics legacy go.mod go.sum; git status --short -- audit journal service metrics legacy go.mod go.sum; test ! -e Makefile && \
echo '"'no Makefile in fixture' || \
true; go vet ./..."
semedit/semantic_insert_declaration (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeEvent(event Event) Event {\n\tevent.Kind = NormalizeKind(event.Kind)\n\treturn event\n}",
  "visibility": "public"
}
10✓ ✓
/bin/zsh -lc "sed -n '1,160p' audit/normalize.go; sed -n '1,120p' audit/sink.go; sed -n '1,120p' audit/fanout.go; sed -n '1,160p' audit/transaction.go; sed -n '1,100p' audit/summary.go; sed -n '1,80p' journal/file.go; sed -n '1,120p' service/dispatch.go; sed -n '1,100p' service/replay.go; git rev-parse --show-toplevel; git status --short --ignored -- audit/normalize.go audit/sink.go"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = NormalizeEvent(event)\nm.Events = append(m.Events, event)\nreturn nil",
  "file": "audit/sink.go",
  "symbol": "(*MemorySink).Write"
}
11✓ ✓
/bin/zsh -lc 'gofmt -d audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go journal/file.go service/dispatch.go service/replay.go && \
go test -race ./...'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = NormalizeEvent(event)\nif err := f.First.Write(event); err != nil {\n\treturn err\n}\nreturn f.Second.Write(event)",
  "file": "audit/fanout.go",
  "symbol": "FanoutSink.Write"
}
12—semedit/semantic_replace_body (✓ ✓)
{
  "body": "for _, event := range b.queue {\n\tevent = NormalizeEvent(event)\n\tif err := b.Sink.Write(event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "audit/transaction.go",
  "symbol": "(*BufferedSink).Commit"
}
13—semedit/semantic_replace_body (✓ ✓)
{
  "body": "switch NormalizeKind(kind) {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
14—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = audit.NormalizeEvent(event)\nreturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
15—semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\nfor _, event := range events {\n\tevent = audit.NormalizeEvent(event)\n\tif err := writeEvent(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
16—semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\nfor _, event := range events {\n\tevent = audit.NormalizeEvent(event)\n\tif err := writeEvent(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/replay.go",
  "symbol": "Replay"
}
17—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = audit.NormalizeEvent(event)\nj.Entries = append(j.Entries, event)\nreturn nil",
  "file": "journal/file.go",
  "symbol": "(*JournalSink).Write"
}
18—✓ ✓
/bin/zsh -lc "git diff -- audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go service/replay.go journal/file.go docs/SUBOPTIMAL_TOOLS.md && \
echo '--- protected-file diff ---' && \
git diff --name-only -- go.mod go.sum audit/*_test.go service/*_test.go metrics/*_test.go legacy/*_test.go api/*_test.go && \
echo '--- changed files ---' && \
git status --short -- audit docs service journal metrics legacy api go.mod go.sum && \
echo '--- formatting check ---' && \
gofmt -d audit journal service"
19—✓ ✓
/bin/zsh -lc "sed -n '1,160p' audit/normalize.go; sed -n '1,80p' audit/sink.go; sed -n '1,80p' service/dispatch.go; sed -n '1,80p' docs/SUBOPTIMAL_TOOLS.md; pwd; git rev-parse --show-toplevel; git ls-files --stage -- audit/normalize.go audit/sink.go"
20—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
21—✓ ✓
/bin/zsh -lc 'go test ./... && \
test ! -e go.sum && \
cmp -s go.mod go.mod'
22—✓ ✓
/bin/zsh -lc "go vet ./... && \
echo '--- protected files present/unchanged by targeted operations ---' && \
ls -l go.mod go.sum 2>/dev/null || \
true && \
echo '--- source references ---' && \
rg -n \"Normalize(Event|Kind)|probe|strings\\.ToLower|metrics|legacy\" audit service journal metrics legacy"

Target: codex/gpt-5.6-luna/medium

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-5.6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)⚠ MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency88.25s84.87sN/A95.09s——
Process Start → First Event0.13s0.13s—0.12s——
First Event → First Tool Call7.42s9.52s—6.51s——
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns11N/A1——
Internal Tool Cycles107N/A10——
Initial Load / Discovery Turns11N/A2——
MCP Discovery / Schema Turns00—0——
Tool Invocations (per run)107N/A10——
Output Tokens36563249N/A4126——
Reasoning / Thinking Tokens12311174N/A1812——
Total Input Tokens321237205828N/A313477——
Cached Input Tokens294656186112N/A288512——
Uncached Input Tokens2658119716N/A24965——
Cost0.42680.3243N/A0.4472——
Cached vs Uncached Token Ratio11.09:19.44:1N/A11.56:1——
Oracle L1: Mutation PolicyPASSPASS—PASS——
Oracle L2: AST InvariantsPASSPASS—PASS——
Oracle L3: Clean BuildPASSPASS—PASS——
Oracle L4: Verification TestPASSPASS—PASS——
Semantic Tool Invocation Verified (per run)N/AFAIL—N/A——
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README.md' -g 'docs/**' -g '*.go' -g 'go.mod' -g 'go.sum' | sed -n '1,160p'"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*AGENTS.override.md'"' | sort | sed -n '1,160p' && \
printf '\\n--- docs ---\\n' && \
rg -n \"PROJECT_BRIEF|delivery|persist|probe|event kind|metrics|legacy\" -g '*.md' -g '*.go' ."
2✓ ✓
/bin/zsh -lc "sed -n '1,220p' docs/audit-sinks.md && \
sed -n '1,240p' audit/event.go && \
sed -n '1,240p' audit/normalize.go && \
sed -n '1,240p' audit/sink.go && \
sed -n '1,260p' service/dispatch.go && \
sed -n '1,180p' audit/summary.go && \
git status --short"
✓ ✓
/bin/zsh -lc "sed -n '1,220p' docs/audit-sinks.md && \
for f in audit/event.go audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go cmd/migrate/main.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,240p' \""'$f"; done && \
printf '"'\\n--- tests (read-only) ---\\n' && \
for f in audit/event_test.go audit/summary_test.go service/dispatch_test.go; do sed -n '1,220p' \""'$f"; done'
3✓ ✓
/bin/zsh -lc "sed -n '1,260p' audit/event_test.go && \
sed -n '1,260p' audit/summary_test.go && \
sed -n '1,260p' service/dispatch_test.go && \
sed -n '1,220p' metrics/writer.go && \
sed -n '1,240p' legacy/export.go && \
sed -n '1,220p' cmd/migrate/main.go && \
sed -n '1,120p' go.mod"
✓ ✓
/bin/zsh -lc "git status --short && \
printf '\\n--- module ---\\n' && \
sed -n '1,80p' go.mod && \
printf '\\n--- all implementation ---\\n' && \
for f in legacy/export.go metrics/writer.go; do printf '\\n%s\\n' \""'$f"; sed -n '"'1,180p' \""'$f"; done && \
printf '"'\\n--- available commands ---\\n' && \
(command -v semedit || \
true) && \
(rg -n \"semantic_|semedit\" . --glob '"'!*.sum'"' --glob '"'!*.mod'"' || \
true)"
4✓ ✓
/bin/zsh -lc "rg -n \"audit|Classify|MemorySink|DispatchAll|Record|probe|health|Kind\" --glob '"'!*.sum'"' --glob '"'!go.mod'"' ."
? ✗
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
git diff -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
make check'
5✓ ✓
/bin/zsh -lc "ls -la && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,220p' PROJECT_BRIEF.md; fi"
✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/normalize.go; sed -n '1,100p' audit/sink.go; sed -n '1,80p' audit/summary.go; sed -n '1,100p' service/dispatch.go; git diff --no-ext-diff -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go; git status --short -- audit service"
6✓ ✓
/bin/zsh -lc "gofmt -w audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
git diff -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go && \
git diff --name-only -- go.mod go.sum '*_test.go'"
✓ ✓
/bin/zsh -lc 'git ls-files -- audit/normalize.go audit/sink.go audit/summary.go service/dispatch.go go.mod audit/event_test.go; go test ./...; go vet ./...; git diff --name-only -- go.mod go.sum audit service; git status --short --untracked-files=no -- audit service go.mod go.sum'
7✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/normalize.go; sed -n '1,100p' audit/sink.go; sed -n '1,100p' audit/summary.go; sed -n '1,100p' service/dispatch.go; git status --short -- audit service go.mod go.sum"
✓ ✓
/bin/zsh -lc "git status --short --ignored -- audit service go.mod go.sum | sed -n '1,80p'; printf '\\n--- protected/test mtimes and content markers ---\\n'; rg -n \"Normalize|probe|go 1\\.23|Test\" audit service go.mod go.sum 2>/dev/null; printf '\\n--- final diff-like changes ---\\n'; git diff --no-index /dev/null audit/normalize.go || \
true"
8✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
git ls-files --stage -- audit/normalize.go audit/sink.go service/dispatch.go && \
git status --short --untracked-files=all | sed -n '1,80p' && \
git diff --no-ext-diff --no-textconv --stat"
—
9✓ ✓
/bin/zsh -lc "set -e
if [ -e Makefile ]; then make check; else echo 'make check unavailable: no Makefile in fixture'; fi
go test ./...
go vet ./...
sha256sum go.mod go.sum 2>/dev/null || \
true
find . -type f -name '*_test.go' -print | sort"
—
10✓ ✓
/bin/zsh -lc "set -e
printf '%s\\n' 'Changed production files:'
rg -n \"NormalizeKind|probe|strings\\.TrimSpace|strings\\.ToLower\" audit service
printf '%s\\n' 'Protected files present and checksums:'
for file in go.mod go.sum; do if [ -e \""'$file" ]; then sha256sum "$file"; else echo "$file: absent"; fi; done
printf '"'%s\\n' 'Test file mtimes/content status:'
git status --short --untracked-files=all -- audit service go.mod go.sum
printf '%s\\n' 'Repository-wide forbidden protocol edits in fixture:'
rg -n \"func Classify|probe|sample|archive\" metrics legacy"
—
⚠ Why no semantic edit tool was used
I did not discover an available semedit MCP server or callable `semantic_*` tools in the provided tool set. I therefore used ordinary editing for this small, localized change.
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS*.md' -g '"'!AGENTS.override.md'"' -g '*.go' -g 'Makefile' -g 'README*' | sort | head -200"
not published
2✓ ✓
/bin/zsh -lc "find . -maxdepth 3 -type f | sort | sed -n '1,240p' && \
printf '\\n--- git status ---\\n' && \
git status --short"
not published
3✓ ✓
/bin/zsh -lc "sed -n '1,240p' docs/audit-sinks.md && \
for f in audit/event.go audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go legacy/export.go metrics/metrics.go metrics/writer.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,260p' \""'$f"; done'
not published
4✓ ✓
/bin/zsh -lc "for f in audit/*_test.go service/*_test.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,300p' \""'$f"; done; printf '"'\\n--- references ---\\n'; rg -n 'NewDispatcher|DispatchAll|\\.Write\\(|Classify\\(|MemorySink|BufferedSink|FanoutSink|audit\\.Event|Kind' --glob '*.go' --glob '"'!**/*_test.go'"'"
not published
5✓ ✓
/bin/zsh -lc "sed -n '1,220p' journal/file.go; sed -n '1,160p' service/replay.go; sed -n '1,160p' cmd/migrate/main.go; sed -n '1,160p' cmd/replay/main.go; sed -n '1,240p' api/router.go; sed -n '1,220p' auth/auth.go; sed -n '1,200p' db/db.go; sed -n '1,160p' cache/cache.go; sed -n '1,160p' health/health.go"
not published
6✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go service/replay.go && \
git diff -- audit/normalize.go audit/summary.go service/dispatch.go service/replay.go && \
go test ./...'
not published
7✓ ✓
/bin/zsh -lc "git diff --check && \
git diff --name-only -- audit service journal metrics legacy go.mod go.sum && \
printf '\\n--- diff ---\\n' && \
git diff -- audit service && \
printf '\\n--- protected/test changes ---\\n' && \
git diff --name-only -- go.mod go.sum '*_test.go' && \
printf '\\n--- make check availability ---\\n' && \
if [ -f Makefile ]; then make check; else echo 'no Makefile in benchmark fixture'; fi"
not published
8✓ ✓
/bin/zsh -lc "git status --short -- audit service journal metrics legacy go.mod go.sum && \
git ls-files -v audit/normalize.go audit/summary.go service/dispatch.go service/replay.go && \
sed -n '1,120p' audit/normalize.go && \
sed -n '1,80p' service/dispatch.go"
not published
9✓ ✓
/bin/zsh -lc 'git rev-parse --show-toplevel; git status --short --untracked-files=all | head -40; git check-ignore -v audit/normalize.go audit/summary.go service/dispatch.go || \
true; git ls-files | head -30'
not published
10✓ ✓
/bin/zsh -lc "go vet ./... && \
printf 'verified: go vet and go test passed; no Makefile present; protected files/tests unchanged\\n'"
not published

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-5.6-luna/medium
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency172.55s116.76s-32.3%103.55s298.02s+187.8%
Process Start → First Event0.13s0.14s—0.14s0.13s—
First Event → First Tool Call14.57s15.04s—13.10s15.69s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns51-80.0%15+400.0%
Internal Tool Cycles1112+9.1%936+300.0%
Initial Load / Discovery Turns21-50.0%26+200.0%
MCP Discovery / Schema Turns00—01—
Tool Invocations (per run)1112+9.1%936+300.0%
Output Tokens289183303-88.6%446131939+616.0%
Reasoning / Thinking Tokens121871739-85.7%241713527+459.7%
Total Input Tokens3148719465882-85.2%4416734686755+961.1%
Cached Input Tokens2813696431616-84.7%4042244424704+994.6%
Uncached Input Tokens33502334266-89.8%37449262051+599.8%
Cost4.31510.5384-87.5%0.59574.8866+720.3%
Cached vs Uncached Token Ratio8.40:112.60:1+50.0%10.79:116.88:1+56.4%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 9 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
printf '%s\\n' '--- files ---' && \
rg --files -g '"'!go.sum'"' -g '"'!go.mod'"' | sort | sed -n '1,160p' && \
printf '%s\\n' '--- docs ---' && \
if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi && \
if [ -f Makefile ]; then sed -n '1,220p' Makefile; fi"
✓ ✓
/bin/zsh -lc "pwd; rg --files -g 'PROJECT_BRIEF.md' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g '"'!go.mod'"' -g '"'!go.sum'"'; printf '\\n-- top-level --\\n'; rg --files -g '"'!go.mod'"' -g '"'!go.sum'"' | head -80"
2✓ ✓
/bin/zsh -lc "git status --short && \
printf '%s\\n' '--- audit/event.go ---' && \
sed -n '1,240p' audit/event.go && \
printf '%s\\n' '--- audit/normalize.go ---' && \
sed -n '1,240p' audit/normalize.go && \
printf '%s\\n' '--- audit/sink.go ---' && \
sed -n '1,240p' audit/sink.go && \
printf '%s\\n' '--- service/dispatch.go ---' && \
sed -n '1,280p' service/dispatch.go && \
printf '%s\\n' '--- docs/audit-sinks.md ---' && \
sed -n '1,260p' docs/audit-sinks.md"
✓ ✓
/bin/zsh -lc "git status --short; printf '\\n-- audit files --\\n'; nl -ba audit/event.go; nl -ba audit/normalize.go; nl -ba audit/sink.go; nl -ba audit/summary.go; printf '\\n-- service --\\n'; nl -ba service/dispatch.go; printf '\\n-- docs --\\n'; nl -ba docs/audit-sinks.md; printf '\\n-- tests references --\\n'; rg -n \"event|probe|sink|normalize|audit|dispatch|legacy|metrics\" audit service legacy metrics cmd --glob '*_test.go' --glob '*.go'"
3✓ ✓
/bin/zsh -lc "for f in audit/*_test.go audit/summary.go cmd/migrate/main.go legacy/export.go metrics/writer.go service/*_test.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,280p' \""'$f"; done'
✓ ✓
/bin/zsh -lc 'for f in audit/*_test.go service/*_test.go metrics/writer.go legacy/export.go cmd/migrate/main.go; do echo "-- $f --"; nl -ba "$f"; done; printf '"'\\n-- files and module --\\n'; rg --files -g '"'!go.mod'"' -g '"'!go.sum'"' | sort; sed -n '1,80p' go.mod"
4✓ ✓
/bin/zsh -lc "rg -n \"probe|health|Classify|Record|DispatchAll|Normalize|normalize|audit\" -g '"'!*.sum'"' -g '"'!go.mod'"' ."
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
5✓ ✓
/bin/zsh -lc "gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
git diff -- audit/normalize.go audit/summary.go service/dispatch.go && \
printf '%s\\n' '--- protected status ---' && \
git status --short -- go.mod go.sum && \
printf '%s\\n' '--- tests ---' && \
go test ./... && \
printf '%s\\n' '--- vet ---' && \
go vet ./..."
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeEvent(event Event) Event {\n\tevent.Kind = NormalizeKind(event.Kind)\n\treturn event\n}"
}
6✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- changed source ---' && \
sed -n '1,120p' audit/normalize.go && \
sed -n '1,120p' audit/summary.go && \
sed -n '1,120p' service/dispatch.go && \
printf '%s\\n' '--- fixture git metadata ---' && \
git status --short --untracked-files=all -- audit/normalize.go audit/summary.go service/dispatch.go && \
git ls-files --stage -- audit/normalize.go audit/summary.go service/dispatch.go && \
printf '%s\\n' '--- full status in fixture ---' && \
git status --short --untracked-files=all | sed -n '1,80p'"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "return d.sink.Write(audit.NormalizeEvent(event))",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
7✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- protected files ---' && \
for f in go.mod go.sum; do if [ -f \""'$f" ]; then shasum -a 256 "$f"; fi; done && \
printf '"'%s\\n' '--- source ---' && \
sed -n '1,160p' audit/normalize.go && \
sed -n '1,160p' audit/summary.go && \
sed -n '1,200p' audit/sink.go && \
sed -n '1,200p' service/dispatch.go && \
printf '%s\\n' '--- docs ---' && \
sed -n '1,160p' docs/audit-sinks.md && \
printf '%s\\n' '--- files ---' && \
rg --files | sort"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "for _, event := range events {\n\t\tif err := sink.Write(audit.NormalizeEvent(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
8✓ ✓
/bin/zsh -lc "gofmt -w audit/sink.go && \
go test ./... && \
go vet ./... && \
git diff --check && \
printf '%s\\n' '--- protected/test status ---' && \
git status --short -- go.mod go.sum audit/event_test.go audit/summary_test.go service/dispatch_test.go legacy/export_test.go metrics/writer_test.go && \
printf '%s\\n' '--- protocols ---' && \
sed -n '1,80p' metrics/writer.go && \
sed -n '1,100p' legacy/export.go && \
printf '%s\\n' '--- audit persistence ---' && \
sed -n '1,120p' audit/sink.go"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "switch NormalizeKind(kind) {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
9✓ ✓
/bin/zsh -lc "sed -n '1,100p' audit/summary.go && \
go test ./... && \
git status --short -- go.mod go.sum audit/*_test.go service/*_test.go legacy/*_test.go metrics/*_test.go"
✓ ✓
/bin/zsh -lc "git diff -- audit/normalize.go audit/summary.go service/dispatch.go; printf '\\n-- protected/test status --\\n'; git status --short -- go.mod go.sum audit/*_test.go service/*_test.go metrics/*_test.go legacy/*_test.go; printf '\\n-- Makefile availability --\\n'; test -f Makefile && \
echo yes || \
echo no"
10✓ ✓
/bin/zsh -lc "sed -n '1,180p' service/dispatch.go && \
go test ./... && \
git status --short -- go.mod go.sum service/*_test.go audit/*_test.go"
? ✗
/bin/zsh -lc "printf '%s\\n' '-- normalize --'; nl -ba audit/normalize.go; printf '%s\\n' '-- summary --'; nl -ba audit/summary.go; printf '%s\\n' '-- dispatch --'; nl -ba service/dispatch.go; printf '%s\\n' '-- git context --'; git rev-parse --show-toplevel; git status --short --untracked-files=all -- audit/normalize.go audit/summary.go service/dispatch.go; git ls-files --error-unmatch audit/normalize.go audit/summary.go service/dispatch.go"
11✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./... && \
git status --short -- go.mod go.sum audit/*_test.go service/*_test.go legacy/*_test.go metrics/*_test.go'
semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": ".",
  "trust_workspace": true
}
12—✓ ✓
/bin/zsh -lc 'go test ./...'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 9 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!AGENTS.override.md'"' -g '"'!go.mod'"' -g '"'!go.sum'"' | sort | sed -n '1,160p' && \
printf '\\n--- status ---\\n' && \
git status --short"
✓ ✓
/bin/zsh -lc "pwd; printf '%s\\n' '--- files ---'; rg --files -g 'PROJECT_BRIEF.md' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g 'Makefile' -g '*.go' -g 'AGENTS.md' -g 'AGENTS.override.md' | sort; printf '%s\\n' '--- git status ---'; git status --short; printf '%s\\n' '--- project brief ---'; if [ -f PROJECT_BRIEF.md ]; then sed -n '1,240p' PROJECT_BRIEF.md; fi; printf '%s\\n' '--- adr index ---'; if [ -f docs/adr/README.md ]; then sed -n '1,220p' docs/adr/README.md; fi; printf '%s\\n' '--- research index ---'; if [ -f docs/research/README.md ]; then sed -n '1,220p' docs/research/README.md; fi"
2✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- docs ---' && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'README*' -g 'docs/**' | sort && \
printf '%s\\n' '--- relevant source symbols ---' && \
rg -n \"audit|probe|event|metric|legacy|sink|normalize|Export|Kind\" --glob '*.go' --glob '"'!**/*_test.go'"' ."
✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- audit files ---'; for f in audit/*.go; do echo \"### "'$f"; sed -n '"'1,260p' \""'$f"; done; printf '"'%s\\n' '--- references ---'; rg -n -i 'audit|probe|event.?kind|normalize|persist|metric|legacy|fanout|sink' --glob '*.go' --glob '"'!**/*_test.go'"' ."
3✓ ✓
/bin/zsh -lc "sed -n '1,240p' docs/audit-sinks.md && \
for f in audit/event.go audit/normalize.go audit/sink.go audit/fanout.go audit/summary.go audit/transaction.go service/dispatch.go service/replay.go journal/file.go legacy/export.go metrics/writer.go metrics/metrics.go cmd/migrate/main.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,240p' \""'$f"; done'
? ✗
/bin/zsh -lc 'for f in service/*.go journal/*.go metrics/*.go legacy/*.go; do echo "### $f"; sed -n '"'1,240p' \""'$f"; done; printf '"'%s\\n' '--- tests ---'; for f in audit/*_test.go service/*_test.go journal/*_test.go metrics/*_test.go legacy/*_test.go; do [ -f \""'$f" ] && \
{ echo "### $f"; sed -n '"'1,260p' \""'$f"; }; done; printf '"'%s\\n' '--- build files ---'; rg --files -g 'go.mod' -g 'Makefile' -g '*.md' | sort | xargs -r -n1 sh -c 'echo \"### "'$0"; sed -n "1,180p" "$0"'"'"
4✓ ✓
/bin/zsh -lc "for f in audit/event_test.go audit/summary_test.go audit/*_test.go service/*_test.go legacy/*_test.go metrics/*_test.go; do printf '\\n--- %s ---\\n' \""'$f"; sed -n '"'1,260p' \""'$f"; done'
✓ ✓
/bin/zsh -lc "rg --files -g 'go.mod' -g 'Makefile' -g '*.md' | sort | while IFS= read -r f; do echo \"### "'$f"; sed -n '"'1,180p' \""'$f"; done'
5✓ ✓
/bin/zsh -lc "git log --oneline --all -8 && \
printf '\\n--- all non-test files ---\\n' && \
rg --files -g '*.go' -g '*.md' -g '"'!AGENTS.override.md'"' | sort && \
printf '\\n--- boundary references ---\\n' && \
rg -n \"NewDispatcher|DispatchAll|Replay|FanoutSink|BufferedSink|JournalSink|Classify\\(\" . --glob '"'!AGENTS.override.md'"'"
cua_repl/js (✓ ✓)
{
  "code": "await cua.getState()",
  "title": "Inspect available computer surfaces"
}
6✓ ✓
/bin/zsh -lc "ls -la && \
if [ -f Makefile ]; then make check; else echo 'no fixture Makefile'; fi"
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func Normalize(event Event) Event {\n\tevent.Kind = strings.ToLower(strings.TrimSpace(event.Kind))\n\treturn event\n}"
}
7✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/fanout.go audit/summary.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go && \
git diff --check && \
go test ./...'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event = Normalize(event)\n\tm.Events = append(m.Events, event)\n\treturn nil",
  "file": "audit/sink.go",
  "symbol": "(*MemorySink).Write"
}
8✓ ✓
/bin/zsh -lc "git diff --name-only && \
printf '\\n--- diff ---\\n' && \
git diff -- audit/normalize.go audit/sink.go audit/fanout.go audit/summary.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go && \
printf '\\n--- protected/test changes ---\\n' && \
git diff --name-only -- go.mod go.sum '*_test.go' && \
printf '\\n--- status ---\\n' && \
git status --short"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event = audit.Normalize(event)\n\tj.Entries = append(j.Entries, event)\n\treturn nil",
  "file": "journal/file.go",
  "symbol": "(*JournalSink).Write"
}
9✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel --show-prefix && \
git ls-files --stage -- audit/normalize.go audit/sink.go && \
sed -n '1,120p' audit/normalize.go && \
git status --short --untracked-files=all -- ."
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "switch Normalize(Event{Kind: kind}).Kind {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
10—✓ ✓
/bin/zsh -lc "git diff -- audit/normalize.go audit/sink.go audit/summary.go journal/file.go; printf '%s\\n' '--- protected diff check ---'; git diff --name-only -- go.mod go.sum; printf '%s\\n' '--- gofmt check ---'; test -z \""'$(gofmt -l audit journal)"; printf '"'gofmt_status=%s\\n' \""'$?"'
11—✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/normalize.go; sed -n '1,100p' audit/sink.go; sed -n '1,100p' audit/summary.go; sed -n '1,80p' journal/file.go; git status --short -- audit journal; git rev-parse --show-toplevel"
12—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
13—✓ ✓
/bin/zsh -lc 'go test ./...'
14—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "for _, event := range events {\n\t\tif err := sink.Write(audit.Normalize(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
15—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "return d.sink.Write(audit.Normalize(event))",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
16—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "for _, event := range events {\n\t\tif err := sink.Write(audit.Normalize(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/replay.go",
  "symbol": "Replay"
}
17—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event = Normalize(event)\n\tif err := f.First.Write(event); err != nil {\n\t\treturn err\n\t}\n\treturn f.Second.Write(event)",
  "file": "audit/fanout.go",
  "symbol": "FanoutSink.Write"
}
18—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "for _, event := range b.queue {\n\t\tif err := b.Sink.Write(Normalize(event)); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "audit/transaction.go",
  "symbol": "(*BufferedSink).Commit"
}
19—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
20—✓ ✓
/bin/zsh -lc 'go test ./... && \
test -z "$(gofmt -l audit journal service)" && \
test -z "$(git diff --name-only -- go.mod go.sum)"'
21—✓ ✓
/bin/zsh -lc "printf '%s\\n' '--- protected hashes ---'; shasum go.mod go.sum 2>/dev/null || \
true; printf '%s\\n' '--- audit boundary ---'; sed -n '1,160p' audit/normalize.go; sed -n '1,160p' audit/sink.go; sed -n '1,120p' service/dispatch.go; sed -n '1,120p' journal/file.go; printf '%s\\n' '--- status ---'; git status --short -- go.mod go.sum audit service journal '*_test.go'"
22—✓ ✓
/bin/zsh -lc 'for f in audit/*.go; do echo "### $f"; sed -n '"'1,220p' \""'$f"; done; printf '"'%s\\n' '--- all kind handling ---'; rg -n 'Kind|Classify|Write\\(' --glob '*.go' --glob '"'!**/*_test.go'"' ."
23—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
24—✓ ✓
/bin/zsh -lc 'go test ./... && \
test -z "$(gofmt -l audit journal service)" && \
test -z "$(git diff --name-only -- go.mod go.sum)"'
25—✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/summary.go; sed -n '1,120p' audit/normalize.go; printf '%s\\n' '--- protected status ---'; git status --short -- go.mod go.sum; printf '%s\\n' '--- tests status ---'; git status --short -- '*_test.go'"
26—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "audit"
}
27—✓ ✓
/bin/zsh -lc 'go test ./audit ./service ./journal ./metrics ./legacy && \
test -z "$(git diff --name-only -- go.mod go.sum)"'
28—✓ ✓
/bin/zsh -lc "sed -n '1,140p' service/dispatch.go; printf '%s\\n' '--- protected status ---'; git status --short -- go.mod go.sum; printf '%s\\n' '--- tests status ---'; git status --short -- '*_test.go'"
29—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "service"
}
30—✓ ✓
/bin/zsh -lc 'go test ./service && \
test -z "$(git diff --name-only -- go.mod go.sum)"'
31—✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/normalize.go; sed -n '1,100p' audit/summary.go; sed -n '1,100p' service/dispatch.go; git status --short -- go.mod go.sum '*_test.go'"
32—semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": false,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
33—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event.Kind = NormalizeKind(event.Kind)\n\treturn event",
  "file": "audit/normalize.go",
  "symbol": "Normalize"
}
34—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "switch NormalizeKind(kind) {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
35—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": false,
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\n\treturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
36—✓ ✓
/bin/zsh -lc 'go test ./...'

Target: codex/gpt-6-luna/high

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-6-luna/high
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency65.63s108.24s+64.9%161.50s278.30s+72.3%
Process Start → First Event0.13s0.12s—0.12s0.93s—
First Event → First Tool Call7.11s6.06s—5.53s5.96s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%550%
Internal Tool Cycles1016+60.0%1328+115.4%
Initial Load / Discovery Turns110%43-25.0%
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)1016+60.0%1328+115.4%
Output Tokens27893300+18.3%2621039762+51.7%
Reasoning / Thinking Tokens16501938+17.5%1669828126+68.4%
Total Input Tokens201453410158+103.6%18112632639234+45.7%
Cached Input Tokens183040362496+98.0%16888322462976+45.8%
Uncached Input Tokens1841347662+158.8%122431176258+44.0%
Cost0.14730.2753+86.9%1.26461.9050+50.6%
Cached vs Uncached Token Ratio9.94:17.61:1-23.5%13.79:113.97:1+1.3%
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestPASSPASS—PASSFAIL—
Semantic Tool Invocation Verified (per run)N/APASS—N/APASS—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g '*.go' -g 'Makefile' -g 'go.mod' -g 'go.sum' | head -200"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS*' -g 'PROJECT_BRIEF.md' -g '*.go' -g 'Makefile' -g 'go.mod' -g 'go.sum' | head -100"
2✓ ✓
/bin/zsh -lc 'cat audit/event.go audit/normalize.go audit/sink.go service/dispatch.go'
✓ ✓
/bin/zsh -lc "cat AGENTS.override.md && \
sed -n '1,240p' audit/event.go && \
sed -n '1,240p' audit/normalize.go && \
sed -n '1,240p' audit/sink.go && \
sed -n '1,240p' service/dispatch.go"
3✓ ✓
/bin/zsh -lc 'cat go.mod && \
ls -la'
✓ ✓
/bin/zsh -lc "rg -n \"probe|event kind|Kind|Deliver|Persist|normalize|legacy|metrics\" . --glob '"'!**/*_test.go'"' --glob '"'!go.sum'"' --glob '"'!go.mod'"'"
4✓ ✓
/bin/zsh -lc "git status --short && \
rg -n \"event|probe|Normalize|persist|Delivery|deliver\" . --glob '"'!**/*_test.go'"'"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' audit/event_test.go && \
sed -n '1,240p' audit/summary.go && \
sed -n '1,240p' audit/summary_test.go && \
sed -n '1,240p' audit/sink_test.go 2>/dev/null; sed -n '1,200p' metrics/writer.go && \
sed -n '1,200p' legacy/export.go && \
rg --files -g 'Makefile' -g 'README*' -g '*.md'"
5✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md audit/summary.go metrics/writer.go legacy/export.go cmd/migrate/main.go'
✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md && \
cat go.mod && \
rg --files'
6✓ ✓
/bin/zsh -lc 'cat service/dispatch_test.go audit/event_test.go audit/summary_test.go metrics/writer_test.go legacy/export_test.go'
✓ ✓
/bin/zsh -lc 'cat service/dispatch_test.go && \
cat legacy/export_test.go && \
cat metrics/writer_test.go'
7✓ ✓
/bin/zsh -lc "rg --files -g 'Makefile' -g '*.sh' -g '*.md'"
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
8✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./... && \
git diff -- audit/normalize.go audit/summary.go service/dispatch.go go.mod go.sum'
✓ ✓
/bin/zsh -lc 'cat audit/normalize.go'
9✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
git status --short -- audit/normalize.go audit/summary.go service/dispatch.go go.mod go.sum && \
cat audit/normalize.go audit/summary.go service/dispatch.go && \
stat -f '%Sm %N' audit/normalize.go audit/summary.go service/dispatch.go"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\n\treturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
10✓ ✓
/bin/zsh -lc 'gofmt -w audit/summary.go && \
go test ./...'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\n\tfor _, event := range events {\n\t\tevent.Kind = audit.NormalizeKind(event.Kind)\n\t\tif err := writeEvent(sink, event); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
11—semedit/semantic_replace_body (✓ ✓)
{
  "body": "switch NormalizeKind(kind) {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
12—? ✗
/bin/zsh -lc 'make check'
13—✓ ✓
/bin/zsh -lc 'go test ./...'
14—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
15—✓ ✓
/bin/zsh -lc 'git status --short && \
git diff -- audit/normalize.go audit/summary.go service/dispatch.go && \
git diff --name-only'
16—✓ ✓
/bin/zsh -lc 'cat audit/normalize.go audit/summary.go service/dispatch.go && \
sha256sum go.mod audit/event_test.go audit/summary_test.go service/dispatch_test.go metrics/writer_test.go legacy/export_test.go'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 9 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g '"'!*vendor*'"' | head -200"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g '*.go' -g 'Makefile' | head -100"
2✓ ✓
/bin/zsh -lc "sed -n '1,240p' audit/event.go && \
sed -n '1,240p' audit/fanout.go && \
sed -n '1,240p' audit/sink.go && \
sed -n '1,200p' audit/normalize.go && \
sed -n '1,200p' audit/transaction.go && \
sed -n '1,240p' docs/audit-sinks.md && \
sed -n '1,200p' db/db.go"
✓ ✓
/bin/zsh -lc "git status --short && \
rg --files | head -100 && \
sed -n '1,240p' audit/event.go && \
sed -n '1,260p' audit/fanout.go && \
sed -n '1,260p' audit/sink.go && \
sed -n '1,260p' service/dispatch.go && \
sed -n '1,220p' audit/normalize.go"
3✓ ✓
/bin/zsh -lc "sed -n '1,260p' service/dispatch.go && \
sed -n '1,260p' service/replay.go && \
sed -n '1,280p' audit/event_test.go && \
sed -n '1,260p' audit/summary.go && \
sed -n '1,260p' audit/summary_test.go && \
sed -n '1,260p' audit/transaction.go && \
sed -n '1,200p' api/router.go && \
sed -n '1,200p' go.mod && \
rg -n \"Probe|probe|Audit|\\.Write\\(|Kind\" --glob '*.go'"
✓ ✓
/bin/zsh -lc "sed -n '1,240p' docs/audit-sinks.md && \
sed -n '1,240p' db/db.go && \
sed -n '1,220p' journal/file.go && \
sed -n '1,200p' audit/transaction.go && \
sed -n '1,220p' metrics/metrics.go && \
sed -n '1,180p' legacy/export.go && \
sed -n '1,180p' service/replay.go && \
sed -n '1,160p' audit/event_test.go && \
sed -n '1,160p' service/dispatch_test.go"
4✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go service/replay.go && \
go test ./...'
? ✗
/bin/zsh -lc "sed -n '1,220p' Makefile && \
rg -n \"\\.Write\\(|Record\\(|DispatchAll|Replay|probe|Kind\" --glob '*.go'"
5✓ ✓
/bin/zsh -lc "git status --short && \
git diff --check && \
git diff -- audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go service/replay.go && \
git diff -- go.mod go.sum && \
git status --short -- '*_test.go'"
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeEvent(event Event) Event {\n\tevent.Kind = strings.ToLower(strings.TrimSpace(event.Kind))\n\treturn event\n}"
}
6✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
git check-ignore -v audit/normalize.go audit/summary.go || \
true && \
sed -n '1,100p' audit/normalize.go && \
sed -n '1,100p' audit/summary.go && \
sed -n '1,120p' audit/transaction.go && \
git diff --no-index /dev/null audit/normalize.go || \
true"
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func IsProbeEvent(event Event) bool {\n\treturn NormalizeEvent(event).Kind == \"probe\"\n}"
}
7✓ ✓
/bin/zsh -lc "sed -n '1,160p' audit/normalize.go && \
sed -n '1,160p' audit/fanout.go && \
sed -n '1,160p' service/dispatch.go && \
sed -n '1,160p' service/replay.go && \
sed -n '1,140p' audit/sink.go && \
sed -n '1,160p' audit/transaction.go && \
sed -n '1,120p' audit/summary.go && \
cat go.mod && \
if [ -f go.sum ]; then cat go.sum; else echo 'go.sum absent'; fi"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "event = NormalizeEvent(event)\nif IsProbeEvent(event) {\n\treturn nil\n}\nm.Events = append(m.Events, event)\nreturn nil",
  "file": "audit/sink.go",
  "symbol": "(*MemorySink).Write"
}
8✓ ✓
/bin/zsh -lc 'go test ./... && \
git diff --check'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "event = NormalizeEvent(event)\nif IsProbeEvent(event) {\n\treturn nil\n}\nif err := f.First.Write(event); err != nil {\n\treturn err\n}\nreturn f.Second.Write(event)",
  "file": "audit/fanout.go",
  "symbol": "(FanoutSink).Write"
}
9✓ ✓
/bin/zsh -lc "sed -n '1,100p' audit/summary.go && \
sed -n '1,100p' audit/normalize.go && \
sed -n '1,100p' audit/summary_test.go && \
cat go.mod && \
test "'! -e go.sum && \
echo '"'go.sum absent' || \
echo 'go.sum present'"
semedit/semantic_replace_body (✓ ✗): replace_body (*BufferedSink).Write in /Users/alessandro/sources/semantic-editor/.scratch/benchmarks/run_codex_semedit_large-default_task-11-mixed-sink-api-migration_1790266169385090000/audit/transaction.go: symbol not found
{
  "auto_organize_imports": true,
  "body": "event = NormalizeEvent(event)\nif IsProbeEvent(event) {\n\treturn nil\n}\nb.queue = append(b.queue, event)\nreturn nil",
  "file": "audit/transaction.go",
  "symbol": "(*BufferedSink).Write"
}
10✓ ✓
/bin/zsh -lc 'go test ./audit && \
git diff --check'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "event = audit.NormalizeEvent(event)\nif audit.IsProbeEvent(event) {\n\treturn nil\n}\nreturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
11✓ ✓
/bin/zsh -lc "sed -n '1,120p' service/dispatch.go && \
sed -n '1,100p' service/replay.go && \
cat go.mod && \
test "'! -e go.sum && \
echo '"'go.sum absent' || \
echo 'go.sum present'"
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "writeEvent := audit.Sink.Write\nfor _, event := range events {\n\tevent = audit.NormalizeEvent(event)\n\tif audit.IsProbeEvent(event) {\n\t\tcontinue\n\t}\n\tif err := writeEvent(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
12✓ ✓
/bin/zsh -lc 'go test ./service && \
git diff --check'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "writeEvent := audit.Sink.Write\nfor _, event := range events {\n\tevent = audit.NormalizeEvent(event)\n\tif audit.IsProbeEvent(event) {\n\t\tcontinue\n\t}\n\tif err := writeEvent(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/replay.go",
  "symbol": "Replay"
}
13✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./...'
semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "event = audit.NormalizeEvent(event)\nif audit.IsProbeEvent(event) {\n\treturn nil\n}\nj.Entries = append(j.Entries, event)\nreturn nil",
  "file": "journal/file.go",
  "symbol": "(*JournalSink).Write"
}
14—semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/transaction.go",
  "placement": "after_symbol",
  "source": "func (b *BufferedSink) Write(event Event) error {\n\tevent = NormalizeEvent(event)\n\tif IsProbeEvent(event) {\n\t\treturn nil\n\t}\n\tb.queue = append(b.queue, event)\n\treturn nil\n}",
  "target_symbol": "Commit"
}
15—✓ ✓
/bin/zsh -lc 'git diff -- audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go service/dispatch.go service/replay.go journal/file.go docs/SUBOPTIMAL_TOOLS.md && \
go test ./...'
16—✓ ✓
/bin/zsh -lc "sed -n '1,200p' audit/normalize.go && \
sed -n '1,200p' audit/transaction.go && \
sed -n '1,120p' docs/SUBOPTIMAL_TOOLS.md && \
git status --short -- audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go service/dispatch.go service/replay.go journal/file.go docs/SUBOPTIMAL_TOOLS.md && \
git rev-parse --show-toplevel"
17—✓ ✓
/bin/zsh -lc 'git status --short -- go.mod go.sum audit/*_test.go service/*_test.go api/*_test.go metrics/*_test.go legacy/*_test.go && \
git diff --exit-code -- go.mod go.sum'
18—✓ ✓
/bin/zsh -lc "sed -n '1,200p' audit/normalize.go && \
sed -n '1,180p' audit/event.go && \
sed -n '1,180p' audit/fanout.go && \
sed -n '1,140p' legacy/export.go && \
rg -n \"IsProbe|Normalize|Classif|control|probe\" . --glob '"'!**/*_test.go'"' && \
git status --short -- go.mod go.sum"
19—✓ ✓
/bin/zsh -lc "cat audit/summary.go && \
rg -n \"Classify\\(\" --glob '*.go' . && \
sed -n '1,140p' audit/summary_test.go && \
sed -n '1,100p' metrics/writer.go && \
sed -n '1,100p' audit/transaction.go && \
git status --short -- go.mod go.sum"
20—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "switch NormalizeEvent(Event{Kind: kind}).Kind {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
21—✓ ✓
/bin/zsh -lc 'go test ./... && \
git status --short -- go.mod go.sum audit/*_test.go service/*_test.go api/*_test.go metrics/*_test.go legacy/*_test.go'
22—✓ ✓
/bin/zsh -lc "sed -n '1,100p' service/dispatch.go && \
sed -n '1,80p' service/replay.go && \
git status --short -- go.mod go.sum service/dispatch_test.go service/replay_test.go && \
go test ./service"
23—semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_start",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
24—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "return NormalizeKind(event.Kind) == \"probe\"",
  "file": "audit/normalize.go",
  "symbol": "IsProbeEvent"
}
25—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "event.Kind = NormalizeKind(event.Kind)\nreturn event",
  "file": "audit/normalize.go",
  "symbol": "NormalizeEvent"
}
26—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "switch NormalizeKind(kind) {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
27—semedit/semantic_replace_body (✓ ✓)
{
  "auto_organize_imports": true,
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\nif audit.IsProbeEvent(event) {\n\treturn nil\n}\nreturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
28—✓ ✓
/bin/zsh -lc 'go test ./... && \
git status --short -- go.mod go.sum audit/*_test.go service/*_test.go api/*_test.go metrics/*_test.go legacy/*_test.go'

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-6-luna/high
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency173.40s121.25s-30.1%143.44s——
Process Start → First Event0.12s0.12s—0.12s——
First Event → First Tool Call14.23s15.47s—17.85s——
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns51-80.0%1——
Internal Tool Cycles1016+60.0%8——
Initial Load / Discovery Turns12+100.0%2——
MCP Discovery / Schema Turns00—0——
Tool Invocations (per run)1016+60.0%8——
Output Tokens285694193-85.3%6061——
Reasoning / Thinking Tokens198592828-85.8%3416——
Total Input Tokens2068407561017-72.9%437440——
Cached Input Tokens1901824517376-72.8%402176——
Uncached Input Tokens16658343641-73.8%35264——
Cost1.49730.3262-78.2%0.3072——
Cached vs Uncached Token Ratio11.42:111.86:1+3.8%11.40:1——
Oracle L1: Mutation PolicyPASSPASS—PASS——
Oracle L2: AST InvariantsPASSPASS—PASS——
Oracle L3: Clean BuildPASSPASS—PASS——
Oracle L4: Verification TestPASSPASS—PASS——
Semantic Tool Invocation Verified (per run)N/APASS—N/A——
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 11 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g 'AGENTS.md' -g 'AGENTS.override.md' -g '*.go' -g 'Makefile' | head -200 && \
rg -n -i 'audit|probe|event kind|eventkind' --glob '*.go' ."
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'go.mod' -g '*.go' -g '"'!**/*_test.go'"' | head -200"
2✓ ✓
/bin/zsh -lc 'cat audit/normalize.go audit/event.go audit/sink.go service/dispatch.go audit/summary.go metrics/writer.go legacy/export.go && \
git status --short && \
find . -maxdepth 2 -type f | sort'
✓ ✓
/bin/zsh -lc "git status --short && \
rg -n --glob '*.go' --glob '"'!**/*_test.go'"' -i 'audit|probe|metric|legacy|event.?kind' ."
3✓ ✓
/bin/zsh -lc "cat docs/audit-sinks.md audit/summary_test.go audit/event_test.go service/dispatch_test.go && \
cat go.mod && \
rg -n 'Normalize|probe|health|Classify|DispatchAll|TransactionalSink' ."
✓ ✓
/bin/zsh -lc 'cat AGENTS.override.md && \
cat service/dispatch.go && \
cat audit/event.go && \
cat audit/normalize.go && \
cat audit/sink.go && \
cat audit/summary.go'
4✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import tempfile
from pathlib import Path

changes = {
    Path('audit/normalize.go'): '''// Package audit normalizes event kinds before they cross the delivery boundary.\\npackage audit\\n\\nimport (\\n\\t\"strings\"\\n)\\n\\nfunc Normalize(event Event) Event {\\n\\tevent.Kind = strings.ToLower(strings.TrimSpace(event.Kind))\\n\\treturn event\\n}\\n''',
    Path('audit/summary.go'): '''// Package audit groups delivery kinds for operational reporting.\\npackage audit\\n\\nfunc Classify(kind string) string {\\n\\tswitch Normalize(Event{Kind: kind}).Kind {\\n\\tcase \"health\", \"probe\":\\n\\t\\treturn \"control\"\\n\\tdefault:\\n\\t\\treturn \"data\"\\n\\t}\\n}\\n''',
    Path('service/dispatch.go'): '''// Package service coordinates application work with the configured audit sink.\\npackage service\\n\\nimport \"example.com/auditapp/audit\"\\n\\ntype Dispatcher struct {\\n\\tsink audit.Sink\\n}\\n\\nfunc NewDispatcher(sink audit.Sink) *Dispatcher {\\n\\treturn &Dispatcher{sink: sink}\\n}\\n\\nfunc (d *Dispatcher) Record(event audit.Event) error {\\n\\treturn d.sink.Write(audit.Normalize(event))\\n}\\n\\nfunc DispatchAll(sink audit.Sink, events []audit.Event) error {\\n\\twriteEvent := audit.Sink.Write\\n\\tfor _, event := range events {\\n\\t\\tif err := writeEvent(sink, audit.Normalize(event)); err "'!= nil {'"\\n\\t\\t\\treturn err\\n\\t\\t}\\n\\t}\\n\\treturn nil\\n}\\n''',
}

for path, content in changes.items():
    previous_mtime = path.stat().st_mtime_ns if path.exists() else 0
    fd, temp_name = tempfile.mkstemp(prefix=f'.{path.name}.', dir=path.parent)
    try:
        with os.fdopen(fd, 'w', encoding='utf-8', newline='') as temp_file:
            temp_file.write(content)
            temp_file.flush()
            os.fsync(temp_file.fileno())
        os.replace(temp_name, path)
        directory_fd = os.open(path.parent, os.O_RDONLY)
        try:
            os.fsync(directory_fd)
        finally:
            os.close(directory_fd)
        current_mtime = path.stat().st_mtime_ns
        if current_mtime <= previous_mtime:
            os.utime(path, ns=(current_mtime, previous_mtime + 1))
    finally:
        if os.path.exists(temp_name):
            os.unlink(temp_name)
PY

gofmt -w audit/normalize.go audit/summary.go service/dispatch.go
git diff -- audit/normalize.go audit/summary.go service/dispatch.go"
✓ ✓
/bin/zsh -lc 'cat metrics/writer.go && \
cat legacy/export.go && \
cat cmd/migrate/main.go'
5✓ ✓
/bin/zsh -lc 'git rev-parse --show-toplevel && \
git status --short -- audit/normalize.go audit/summary.go service/dispatch.go && \
git check-ignore -v audit/normalize.go audit/summary.go service/dispatch.go || \
true && \
cat audit/normalize.go audit/summary.go service/dispatch.go && \
git diff --no-index /dev/null audit/normalize.go || \
true'
✓ ✓
/bin/zsh -lc 'rg --files'
6✓ ✓
/bin/zsh -lc 'go test ./...'
✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md'
7✓ ✓
/bin/zsh -lc "cat audit/normalize.go audit/event.go audit/summary.go service/dispatch.go audit/sink.go && \
git status --short -- go.mod go.sum audit service metrics legacy && \
git check-ignore -v audit/normalize.go service/dispatch.go go.mod go.sum || \
true && \
rg -n 'Normalize\\(|Classify\\(|\\.Write\\(' audit service metrics legacy"
✓ ✓
/bin/zsh -lc 'cat service/dispatch_test.go && \
cat audit/summary_test.go && \
cat audit/event_test.go'
8✓ ✓
/bin/zsh -lc 'cat service/dispatch.go audit/normalize.go && \
git status --short -- go.mod go.sum'
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "public",
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
9✓ ✓
/bin/zsh -lc "cat audit/normalize.go audit/summary.go service/dispatch.go && \
cat go.mod && \
if [ -f go.sum ]; then wc -l go.sum; else printf 'go.sum absent\\n'; fi"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "switch NormalizeKind(kind) {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
10✓ ✓
/bin/zsh -lc "python3 - <<'PY'
import os
import tempfile
from pathlib import Path

changes = {
    Path('audit/normalize.go'): '''// Package audit normalizes event kinds before they cross the delivery boundary.\\npackage audit\\n\\nimport \"strings\"\\n\\nfunc NormalizeKind(kind string) string {\\n\\treturn strings.ToLower(strings.TrimSpace(kind))\\n}\\n\\nfunc Normalize(event Event) Event {\\n\\tevent.Kind = NormalizeKind(event.Kind)\\n\\treturn event\\n}\\n''',
    Path('audit/summary.go'): '''// Package audit groups delivery kinds for operational reporting.\\npackage audit\\n\\nfunc Classify(kind string) string {\\n\\tswitch NormalizeKind(kind) {\\n\\tcase \"health\", \"probe\":\\n\\t\\treturn \"control\"\\n\\tdefault:\\n\\t\\treturn \"data\"\\n\\t}\\n}\\n''',
    Path('service/dispatch.go'): '''// Package service coordinates application work with the configured audit sink.\\npackage service\\n\\nimport \"example.com/auditapp/audit\"\\n\\ntype Dispatcher struct {\\n\\tsink audit.Sink\\n}\\n\\nfunc NewDispatcher(sink audit.Sink) *Dispatcher {\\n\\treturn &Dispatcher{sink: sink}\\n}\\n\\nfunc (d *Dispatcher) Record(event audit.Event) error {\\n\\tevent.Kind = audit.NormalizeKind(event.Kind)\\n\\treturn d.sink.Write(event)\\n}\\n\\nfunc DispatchAll(sink audit.Sink, events []audit.Event) error {\\n\\twriteEvent := audit.Sink.Write\\n\\tfor _, event := range events {\\n\\t\\tevent.Kind = audit.NormalizeKind(event.Kind)\\n\\t\\tif err := writeEvent(sink, event); err "'!= nil {'"\\n\\t\\t\\treturn err\\n\\t\\t}\\n\\t}\\n\\treturn nil\\n}\\n''',
}

for path, content in changes.items():
    previous_mtime = path.stat().st_mtime_ns
    fd, temp_name = tempfile.mkstemp(prefix=f'.{path.name}.', dir=path.parent)
    try:
        with os.fdopen(fd, 'w', encoding='utf-8', newline='') as temp_file:
            temp_file.write(content)
            temp_file.flush()
            os.fsync(temp_file.fileno())
        os.replace(temp_name, path)
        directory_fd = os.open(path.parent, os.O_RDONLY)
        try:
            os.fsync(directory_fd)
        finally:
            os.close(directory_fd)
        current_mtime = path.stat().st_mtime_ns
        if current_mtime <= previous_mtime:
            os.utime(path, ns=(current_mtime, previous_mtime + 1))
    finally:
        if os.path.exists(temp_name):
            os.unlink(temp_name)
PY
gofmt -w audit/normalize.go audit/summary.go service/dispatch.go
go test ./..."
semedit/semantic_insert_function (✓ ✓)
{
  "access_modifier": "private",
  "file": "service/dispatch.go",
  "placement": "file_end",
  "source": "func deliver(sink audit.Sink, event audit.Event) error {\n\tevent.Kind = audit.NormalizeKind(event.Kind)\n\treturn sink.Write(event)\n}"
}
11—semedit/semantic_replace_body (✓ ✓)
{
  "body": "return deliver(d.sink, event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
12—semedit/semantic_replace_body (✓ ✓)
{
  "body": "for _, event := range events {\n\tif err := deliver(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
13—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
14—✓ ✓
/bin/zsh -lc 'git diff -- audit/normalize.go audit/summary.go service/dispatch.go && \
git status --short -- audit/normalize.go audit/summary.go service/dispatch.go service/dispatch_test.go audit/summary_test.go audit/event_test.go go.mod go.sum'
15—✓ ✓
/bin/zsh -lc 'go test -mod=readonly ./...'
16—✓ ✓
/bin/zsh -lc 'cat audit/normalize.go && \
cat audit/summary.go && \
cat service/dispatch.go && \
git status --short --untracked-files=all'
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'Makefile' -g '*.go' | head -100 && \
git status --short"
not published
2✓ ✓
/bin/zsh -lc "rg -n \"Event|event|Probe|probe|Persist|persist|Deliver|deliver|Sink|sink|Normalize|normalize\" --glob '*.go' . && \
find . -maxdepth 2 -type f -not -path './.git/*' | sort | head -120"
not published
3? ✗
/bin/zsh -lc 'cat AGENTS.override.md && \
cat audit/normalize.go audit/event.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go service/replay.go journal/file.go metrics/writer.go metrics/metrics.go legacy/export.go && \
cat docs/audit-sinks.md && \
cat Makefile go.mod'
not published
4✓ ✓
/bin/zsh -lc "cat api/router.go db/db.go models/models.go config/config.go logging/logging.go health/health.go auth/auth.go cache/cache.go utils/utils.go cmd/migrate/main.go cmd/replay/main.go audit/summary_test.go audit/event_test.go service/dispatch_test.go metrics/writer_test.go legacy/export_test.go && \
rg -n \"\\.Write\\(|DispatchAll|Replay\\(|NewDispatcher|Classify\\(\" --glob '*.go' ."
not published
5✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go service/replay.go && \
go test ./...'
not published
6✓ ✓
/bin/zsh -lc 'git diff --check -- .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/audit/normalize.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/audit/summary.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/service/dispatch.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/service/replay.go && \
git status --short -- .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/audit/normalize.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/audit/summary.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/service/dispatch.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/service/replay.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/go.mod .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/go.sum && \
git diff -- .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/audit/normalize.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/audit/summary.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/service/dispatch.go .scratch/benchmarks/run_codex_baseline-diff_large-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790266310931757000/service/replay.go'
not published
7? ✗
/bin/zsh -lc 'cat audit/normalize.go audit/summary.go service/dispatch.go service/replay.go && \
git diff --check --no-index /dev/null audit/normalize.go >/dev/null; test -f go.mod && \
test -f go.sum'
not published
8? ✗
/bin/zsh -lc 'ls -l go.mod go.sum'
not published

Target: codex/gpt-6-luna/medium

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-6-luna/medium
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)⚠ MCP (Large)Δ (Large)
Wall-Clock Latency114.70s85.98s-25.0%144.34s92.12sN/A
Process Start → First Event0.12s0.12s—0.13s0.12s—
First Event → First Tool Call5.42s5.65s—6.00s5.39s—
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns51-80.0%51N/A
Internal Tool Cycles14140%1210N/A
Initial Load / Discovery Turns31-66.7%21N/A
MCP Discovery / Schema Turns00—00—
Tool Invocations (per run)14140%1210N/A
Output Tokens160292047-87.2%151403326N/A
Reasoning / Thinking Tokens4084905-77.8%59691057N/A
Total Input Tokens1636853279526-82.9%1675254247473N/A
Cached Input Tokens1532160253952-83.4%1544192227584N/A
Uncached Input Tokens10469325574-75.6%13106219889N/A
Cost0.89620.1643-81.7%0.97760.1614N/A
Cached vs Uncached Token Ratio14.63:19.93:1-32.1%11.78:111.44:1N/A
Oracle L1: Mutation PolicyPASSPASS—PASSPASS—
Oracle L2: AST InvariantsPASSPASS—PASSPASS—
Oracle L3: Clean BuildPASSPASS—PASSPASS—
Oracle L4: Verification TestFAILPASS—PASSPASS—
Semantic Tool Invocation Verified (per run)N/APASS—N/AFAIL—
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 10 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS.md' -g 'PROJECT_BRIEF.md' -g '*.go' -g 'Makefile' | head -200"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'Makefile' -g '*.go' -g 'docs/**' | head -100"
2✓ ✓
/bin/zsh -lc "rg --files -g 'PROJECT_BRIEF.md' -g 'Makefile' -g 'AGENTS.md'; git status --short; sed -n '1,240p' audit/event.go; sed -n '1,240p' audit/normalize.go; sed -n '1,220p' audit/sink.go; sed -n '1,260p' service/dispatch.go; sed -n '1,200p' metrics/writer.go; sed -n '1,220p' legacy/export.go"
✓ ✓
/bin/zsh -lc "cat docs/audit-sinks.md && \
sed -n '1,240p' service/dispatch.go && \
sed -n '1,240p' audit/event.go && \
sed -n '1,240p' audit/normalize.go && \
sed -n '1,240p' audit/sink.go"
3✓ ✓
/bin/zsh -lc 'cat service/dispatch_test.go; cat audit/event_test.go; cat audit/summary.go; cat audit/summary_test.go; cat go.mod; ls -la;'
✓ ✓
/bin/zsh -lc 'rg --files'
4✓ ✓
/bin/zsh -lc 'cat cmd/migrate/main.go; rg -n "Normalize|probe|Record|DispatchAll|make check" .'
✓ ✓
/bin/zsh -lc 'cat service/dispatch_test.go audit/event_test.go audit/summary.go audit/summary_test.go legacy/export.go metrics/writer.go'
5✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os, tempfile

path = Path('audit/normalize.go')
content = '''// Package audit defines event-kind normalization for the delivery boundary.\\npackage audit\\n\\nimport (\\n\\t\"strings\"\\n)\\n\\nfunc NormalizeKind(kind string) string {\\n\\treturn strings.ToLower(strings.TrimSpace(kind))\\n}\\n'''
fd, tmp = tempfile.mkstemp(dir=path.parent, prefix='.normalize-', text=True)
try:
    with os.fdopen(fd, 'w') as f:
        f.write(content)
        f.flush()
        os.fsync(f.fileno())
    os.replace(tmp, path)
finally:
    if os.path.exists(tmp):
        os.unlink(tmp)

path = Path('service/dispatch.go')
content = '''// Package service coordinates application work with the configured audit sink.\\npackage service\\n\\nimport \"example.com/auditapp/audit\"\\n\\ntype Dispatcher struct {\\n\\tsink audit.Sink\\n}\\n\\nfunc NewDispatcher(sink audit.Sink) *Dispatcher {\\n\\treturn &Dispatcher{sink: sink}\\n}\\n\\nfunc (d *Dispatcher) Record(event audit.Event) error {\\n\\tevent.Kind = audit.NormalizeKind(event.Kind)\\n\\tif event.Kind == \"probe\" {\\n\\t\\treturn nil\\n\\t}\\n\\treturn d.sink.Write(event)\\n}\\n\\nfunc DispatchAll(sink audit.Sink, events []audit.Event) error {\\n\\tfor _, event := range events {\\n\\t\\tevent.Kind = audit.NormalizeKind(event.Kind)\\n\\t\\tif event.Kind == \"probe\" {\\n\\t\\t\\tcontinue\\n\\t\\t}\\n\\t\\tif err := sink.Write(event); err "'!= nil {'"\\n\\t\\t\\treturn err\\n\\t\\t}\\n\\t}\\n\\treturn nil\\n}\\n'''
fd, tmp = tempfile.mkstemp(dir=path.parent, prefix='.dispatch-', text=True)
try:
    with os.fdopen(fd, 'w') as f:
        f.write(content)
        f.flush()
        os.fsync(f.fileno())
    os.replace(tmp, path)
finally:
    if os.path.exists(tmp):
        os.unlink(tmp)
PY
gofmt -w audit/normalize.go service/dispatch.go
go test ./..."
✓ ✓
/bin/zsh -lc 'cat go.mod && \
git status --short'
6✓ ✓
/bin/zsh -lc 'git diff -- audit/normalize.go service/dispatch.go go.mod go.sum; git status --short -- audit/normalize.go service/dispatch.go go.mod go.sum;'
semedit/semantic_insert_function (✓ ✓)
{
  "file": "audit/normalize.go",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
7? ✗
/bin/zsh -lc 'git status --short -- .; git diff --no-index /dev/null audit/normalize.go; git diff --no-index /dev/null service/dispatch.go'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "switch NormalizeKind(kind) {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
8✓ ✓
/bin/zsh -lc "pwd; git status --short -- .; find . -maxdepth 3 -type f -print; sed -n '1,180p' audit/normalize.go; sed -n '1,200p' audit/sink.go; sed -n '1,200p' audit/event.go; sed -n '1,220p' service/dispatch.go; cat go.mod; test "'! -f go.sum || \
cat go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\n\treturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
9✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md; cat AGENTS.override.md;'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\n\tfor _, event := range events {\n\t\tevent.Kind = audit.NormalizeKind(event.Kind)\n\t\tif err := writeEvent(sink, event); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
10? ✗
/bin/zsh -lc 'go test ./...; git diff --no-index /dev/null audit/normalize.go; git diff --no-index /dev/null service/dispatch.go'
✓ ✓
/bin/zsh -lc "sed -n '1,120p' audit/normalize.go && \
sed -n '1,100p' audit/summary.go && \
sed -n '1,120p' service/dispatch.go"
11✓ ✓
/bin/zsh -lc "sed -n '1,180p' audit/summary.go; sed -n '1,100p' audit/normalize.go; sed -n '1,100p' audit/summary_test.go; cat go.mod;"
? ✗
/bin/zsh -lc 'make check'
12✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os, tempfile
path = Path('audit/summary.go')
content = '''// Package audit groups delivery kinds for operational reporting.\\npackage audit\\n\\nfunc Classify(kind string) string {\\n\\tswitch NormalizeKind(kind) {\\n\\tcase \"health\", \"probe\":\\n\\t\\treturn \"control\"\\n\\tdefault:\\n\\t\\treturn \"data\"\\n\\t}\\n}\\n'''
fd, tmp = tempfile.mkstemp(dir=path.parent, prefix='.summary-', text=True)
try:
    with os.fdopen(fd, 'w') as f:
        f.write(content)
        f.flush()
        os.fsync(f.fileno())
    os.replace(tmp, path)
finally:
    if os.path.exists(tmp):
        os.unlink(tmp)
PY
gofmt -w audit/summary.go
go test ./..."
✓ ✓
/bin/zsh -lc "git diff -- audit/normalize.go audit/summary.go service/dispatch.go && \
git status --short -- audit/normalize.go audit/summary.go service/dispatch.go go.mod go.sum '*_test.go'"
13✓ ✓
/bin/zsh -lc "sed -n '1,180p' service/dispatch.go; sed -n '1,80p' audit/normalize.go; cat go.mod; if test -f go.sum; then cat go.sum; fi; go test ./..."
✓ ✓
/bin/zsh -lc 'go test ./...'
14✓ ✓
/bin/zsh -lc 'go test ./...'
✓ ✓
/bin/zsh -lc "git status --short --untracked-files=all | rg 'audit/(normalize|summary)\\.go|service/dispatch\\.go|go\\.mod|go\\.sum|_test\\.go' || \
true; git check-ignore -v audit/normalize.go audit/summary.go service/dispatch.go || \
true; git rev-parse --show-toplevel"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 15 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 17 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'Makefile' -g '*.go' -g 'README*' -g 'docs/**' | head -200"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g 'go.mod' -g 'go.sum' -g 'docs/**' -g '*.go' | head -160"
2? ✗
/bin/zsh -lc 'ls -la && \
cat docs/audit-sinks.md && \
cat audit/normalize.go && \
cat audit/event.go && \
cat audit/fanout.go && \
cat audit/sink.go && \
cat service/dispatch.go && \
cat Makefile'
✓ ✓
/bin/zsh -lc "cat AGENTS.override.md && \
cat docs/audit-sinks.md && \
sed -n '1,240p' audit/event.go && \
sed -n '1,260p' audit/fanout.go && \
sed -n '1,240p' audit/sink.go && \
sed -n '1,220p' audit/normalize.go && \
sed -n '1,240p' service/dispatch.go && \
git status --short"
3✓ ✓
/bin/zsh -lc "cat audit/transaction.go audit/summary.go db/db.go journal/file.go metrics/metrics.go legacy/export.go && \
rg -n \"probe|Probe|Write\\(|Normalize|kind\" --glob '*.go' ."
✓ ✓
/bin/zsh -lc "cat audit/transaction.go && \
cat audit/summary.go && \
cat audit/event_test.go && \
cat audit/summary_test.go && \
cat service/dispatch_test.go && \
rg -n 'audit\\.|NewDispatcher|DispatchAll|Probe|probe|Kind|MemorySink|TransactionalSink' --glob '"'!**/*_test.go'"'"
4✓ ✓
/bin/zsh -lc 'cat audit/*_test.go service/*_test.go metrics/writer.go metrics/writer_test.go && \
find . -maxdepth 2 -type f | sort'
✓ ✓
/bin/zsh -lc 'cat service/replay.go && \
cat journal/file.go && \
cat metrics/writer.go && \
cat legacy/export.go && \
cat metrics/metrics.go && \
cat legacy/export_test.go && \
cat metrics/writer_test.go && \
cat go.mod'
5✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./...'
? ✗
/bin/zsh -lc "rg -n 'make check|semantic_' Makefile"
6✓ ✓
/bin/zsh -lc 'git status --short && \
git diff --check && \
git diff -- audit/normalize.go audit/summary.go service/dispatch.go && \
git diff -- go.mod go.sum'
✓ ✓
/bin/zsh -lc "rg --files -g 'Makefile' -g 'go.work' -g '*.go' -g 'README*' -g '.codex/**' | head -100"
7✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go service/dispatch.go && \
go test ./... && \
git diff --check && \
git status --short -- go.mod go.sum'
✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os, tempfile
root=Path('.')
changes={
'audit/normalize.go':'''// Package audit defines normalization at the event delivery boundary.
package audit

import \"strings\"

func NormalizeKind(kind string) string {
\\treturn strings.ToLower(strings.TrimSpace(kind))
}

func Normalize(event Event) Event {
\\tevent.Kind = NormalizeKind(event.Kind)
\\treturn event
}

func Deliver(sink Sink, event Event) error {
\\tevent = Normalize(event)
\\tif Classify(event.Kind) == \"control\" {
\\t\\treturn nil
\\t}
\\treturn sink.Write(event)
}
''',
'audit/summary.go':'''// Package audit groups delivery kinds for operational reporting.
package audit

func Classify(kind string) string {
\\tswitch NormalizeKind(kind) {
\\tcase \"health\", \"probe\":
\\t\\treturn \"control\"
\\tdefault:
\\t\\treturn \"data\"
\\t}
}
''',
'audit/fanout.go':'''// Package audit delivers normalized events to configured destinations.
package audit

type FanoutSink struct {
\\tFirst  Sink
\\tSecond Sink
}

func (f FanoutSink) Write(event Event) error {
\\tevent = Normalize(event)
\\tif Classify(event.Kind) == \"control\" {
\\t\\treturn nil
\\t}
\\tif err := f.First.Write(event); err "'!= nil {
'"\\t\\treturn err
\\t}
\\treturn f.Second.Write(event)
}
''',
'audit/transaction.go':'''// Package audit buffers events until transactional delivery commits.
package audit

type BufferedSink struct {
\\tSink
\\tqueue []Event
}

func (b *BufferedSink) Begin() error {
\\tb.queue = b.queue[:0]
\\treturn nil
}

func (b *BufferedSink) Commit() error {
\\tfor _, event := range b.queue {
\\t\\tif err := Deliver(b.Sink, event); err "'!= nil {
'"\\t\\t\\treturn err
\\t\\t}
\\t}
\\treturn nil
}
''',
'service/dispatch.go':'''// Package service coordinates application work with the configured audit sink.
package service

import \"example.com/auditapp/audit\"

type Dispatcher struct {
\\tsink audit.Sink
}

func NewDispatcher(sink audit.Sink) *Dispatcher {
\\treturn &Dispatcher{sink: sink}
}

func (d *Dispatcher) Record(event audit.Event) error {
\\treturn audit.Deliver(d.sink, event)
}

func DispatchAll(sink audit.Sink, events []audit.Event) error {
\\tfor _, event := range events {
\\t\\tif err := audit.Deliver(sink, event); err "'!= nil {
'"\\t\\t\\treturn err
\\t\\t}
\\t}
\\treturn nil
}
''',
'service/replay.go':'''// Package service contains replay helpers for previously captured audit events.
package service

import \"example.com/auditapp/audit\"

func Replay(sink audit.Sink, events []audit.Event) error {
\\tfor _, event := range events {
\\t\\tif err := audit.Deliver(sink, event); err "'!= nil {
'"\\t\\t\\treturn err
\\t\\t}
\\t}
\\treturn nil
}
'''
}
for name, data in changes.items():
    path=root/name
    fd,tmp=tempfile.mkstemp(dir=path.parent, prefix=path.name+'.')
    try:
        with os.fdopen(fd,'w') as f:
            f.write(data); f.flush(); os.fsync(f.fileno())
        os.replace(tmp,path)
    finally:
        if os.path.exists(tmp): os.unlink(tmp)
PY
gofmt -w audit/normalize.go audit/summary.go audit/fanout.go audit/transaction.go service/dispatch.go service/replay.go
git diff -- audit service metrics legacy go.mod go.sum"
8✓ ✓
/bin/zsh -lc 'git status --short -- go.mod go.sum && \
git diff -- go.mod go.sum && \
cat audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go service/dispatch.go audit/summary.go'
✓ ✓
/bin/zsh -lc 'git status --short -- . && \
git diff --no-index /dev/null audit/normalize.go | head -80 && \
go test ./...'
9✓ ✓
/bin/zsh -lc 'cat audit/summary.go audit/normalize.go && \
git status --short -- go.mod go.sum && \
go test ./audit ./service && \
git diff --check'
✓ ✓
/bin/zsh -lc 'git rev-parse --show-toplevel && \
git check-ignore -v audit/normalize.go audit/summary.go || \
true && \
git diff --no-index /dev/null audit/summary.go | head -50 && \
git diff --no-index /dev/null service/dispatch.go | head -70 && \
sha256sum go.mod go.sum 2>/dev/null || \
true'
10✓ ✓
/bin/zsh -lc 'cat service/dispatch.go && \
git status --short -- go.mod go.sum && \
go test ./service && \
git diff --check'
✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os, tempfile
changes={
'audit/normalize.go':'''// Package audit defines normalization at the event delivery boundary.
package audit

import \"strings\"

func NormalizeKind(kind string) string {
\\treturn strings.ToLower(strings.TrimSpace(kind))
}

func Normalize(event Event) Event {
\\tevent.Kind = NormalizeKind(event.Kind)
\\treturn event
}

func Deliver(sink Sink, event Event) error {
\\treturn sink.Write(Normalize(event))
}
''',
'audit/fanout.go':'''// Package audit delivers normalized events to configured destinations.
package audit

type FanoutSink struct {
\\tFirst  Sink
\\tSecond Sink
}

func (f FanoutSink) Write(event Event) error {
\\tevent = Normalize(event)
\\tif err := f.First.Write(event); err "'!= nil {
'"\\t\\treturn err
\\t}
\\treturn f.Second.Write(event)
}
'''
}
for name,data in changes.items():
    path=Path(name); fd,tmp=tempfile.mkstemp(dir=path.parent,prefix=path.name+'.')
    try:
        with os.fdopen(fd,'w') as f:
            f.write(data); f.flush(); os.fsync(f.fileno())
        os.replace(tmp,path)
    finally:
        if os.path.exists(tmp): os.unlink(tmp)
PY
gofmt -w audit/normalize.go audit/fanout.go
go test ./..."
11✓ ✓
/bin/zsh -lc 'cat audit/normalize.go audit/summary.go service/dispatch.go && \
git status --short -- go.mod go.sum'
—
12✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./... && \
git diff --check && \
git status --short -- go.mod go.sum'
—
⚠ Why no semantic edit tool was used
I did not discover or call any `semantic_*` tools from the semedit MCP server; I used ordinary file editing and Go formatting instead.

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-6-luna/medium
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency106.71s240.60s+125.5%155.63s——
Process Start → First Event0.13s0.12s—0.13s——
First Event → First Tool Call7.56s11.34s—6.82s——
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns550%5——
Internal Tool Cycles1335+169.2%12——
Initial Load / Discovery Turns330%4——
MCP Discovery / Schema Turns00—0——
Tool Invocations (per run)1335+169.2%12——
Output Tokens1368924040+75.6%25645——
Reasoning / Thinking Tokens586012107+106.6%11343——
Total Input Tokens25035524459430+78.1%2339386——
Cached Input Tokens22545924234496+87.8%2198784——
Uncached Input Tokens248960224934-9.7%140602——
Cost1.43042.0728+44.9%1.3636——
Cached vs Uncached Token Ratio9.06:118.83:1+107.9%15.64:1——
Oracle L1: Mutation PolicyPASSPASS—PASS——
Oracle L2: AST InvariantsPASSPASS—PASS——
Oracle L3: Clean BuildPASSPASS—PASS——
Oracle L4: Verification TestFAILFAIL—FAIL——
Semantic Tool Invocation Verified (per run)N/APASS—N/A——
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 17 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 13 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g '*.go' -g 'go.mod' -g 'AGENTS*' -g 'docs/**' | head -120"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'docs/adr/README.md' -g 'docs/research/README.md' -g 'AGENTS.md' -g '"'!**/*_test.go'"' -g '*.go' | head -160 && \
git status --short"
2✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md && \
cat audit/event.go audit/normalize.go audit/sink.go service/dispatch.go cmd/migrate/main.go && \
cat audit/event_test.go audit/summary.go'
✓ ✓
/bin/zsh -lc 'rg --files'
3✓ ✓
/bin/zsh -lc 'cat audit/summary_test.go service/dispatch_test.go metrics/writer.go legacy/export.go && \
cat go.mod && \
git status --short'
✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md && \
cat audit/event.go && \
cat audit/normalize.go && \
cat audit/sink.go && \
cat service/dispatch.go && \
cat metrics/writer.go && \
cat legacy/export.go'
4✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./...'
semedit/semantic_insert_function (✓ ✓)
{
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func Normalize(event Event) Event {\n\tevent.Kind = strings.ToLower(strings.TrimSpace(event.Kind))\n\treturn event\n}"
}
5✓ ✓
/bin/zsh -lc 'git diff -- audit/normalize.go audit/summary.go service/dispatch.go go.mod go.sum && \
git status --short -- audit/normalize.go audit/summary.go service/dispatch.go audit/*test.go service/*test.go go.mod go.sum && \
git diff --check -- audit/normalize.go audit/summary.go service/dispatch.go'
semedit/semantic_insert_function (✓ ✓)
{
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func IsProbe(event Event) bool {\n\treturn Normalize(event).Kind == \"probe\"\n}"
}
6✓ ✓
/bin/zsh -lc 'cat audit/normalize.go audit/summary.go service/dispatch.go && \
git rev-parse --show-toplevel && \
git status --short --untracked-files=all | head -30'
semedit/semantic_insert_function (✓ ✓)
{
  "file": "service/dispatch.go",
  "placement": "file_end",
  "source": "func deliver(sink audit.Sink, event audit.Event) error {\n\tevent = audit.Normalize(event)\n\tif audit.IsProbe(event) {\n\t\treturn nil\n\t}\n\treturn sink.Write(event)\n}"
}
7✓ ✓
/bin/zsh -lc 'pwd && \
cat docs/audit-sinks.md audit/event.go audit/normalize.go audit/sink.go service/dispatch.go && \
git status --short -- go.mod go.sum audit service && \
git diff -- audit go.mod go.sum'
semedit/semantic_replace_body (✓ ✗): replace_body Record in /Users/alessandro/sources/semantic-editor/.scratch/benchmarks/run_codex_semedit_small-prefer_discover_semedit_task-11-mixed-sink-api-migration_1790265415962817000/service/dispatch.go: symbol not found
{
  "body": "return deliver(d.sink, event)",
  "file": "service/dispatch.go",
  "symbol": "Record"
}
8✓ ✓
/bin/zsh -lc "rg -n 'Normalize|Classify|\\.Write\\(|DispatchAll|Record\\(' --glob '"'!**/*test.go'"' . && \
cat audit/summary.go && \
cat audit/summary_test.go service/dispatch_test.go"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "for _, event := range events {\n\t\tif err := deliver(sink, event); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\treturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
9✓ ✓
/bin/zsh -lc 'go test ./... && \
git status --short -- go.mod go.sum'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = audit.Normalize(event)\n\tif event.Kind == \"probe\" {\n\t\treturn nil\n\t}\n\treturn sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "deliver"
}
10✓ ✓
/bin/zsh -lc 'cat audit/normalize.go audit/summary.go audit/event.go && \
git status --short -- go.mod go.sum && \
git diff -- audit/normalize.go audit/summary.go'
semedit/semantic_replace_body (✓ ✓)
{
  "body": "return deliver(d.sink, event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
11✓ ✓
/bin/zsh -lc 'go test ./audit ./service && \
git status --short -- go.mod go.sum'
✓ ✓
/bin/zsh -lc 'ls -la docs && \
git status --short -- audit service go.mod go.sum'
12✓ ✓
/bin/zsh -lc 'cat service/dispatch.go audit/normalize.go && \
git status --short -- go.mod go.sum && \
go test ./service'
✓ ✓
/bin/zsh -lc "python3 -c 'from pathlib import Path; import os,tempfile,time; p=Path(\"docs/SUBOPTIMAL_TOOLS.md\"); p.parent.mkdir(parents=True,exist_ok=True); content=\"# Suboptimal tool behavior\\n\\nThis file records semantic editing tool failures and workarounds required by the workspace instructions.\\n\\n## 2026-09-24: semantic_replace_body symbol lookup\\n\\n- Tool: "'`semantic_replace_body`'"\\n- Target: "'`service/dispatch.go`'"\\n- Observed failure: requesting symbol "'`Record` returned `symbol not found`. The method requires its receiver-qualified name.'"\\n- Workaround: retried with "'`(*Dispatcher).Record`, which succeeded.'"\\n- Root cause: the initial tool argument did not match the method identifier expected by the tool.\\n\"; fd,tmp=tempfile.mkstemp(dir=str(p.parent),prefix=\".SUBOPTIMAL_TOOLS.\"); f=os.fdopen(fd,\"w\"); f.write(content); f.flush(); os.fsync(f.fileno()); f.close(); os.replace(tmp,p); os.utime(p,None)'"
13✓ ✓
/bin/zsh -lc 'cat audit/normalize.go audit/summary.go service/dispatch.go && \
git status --short -- go.mod go.sum && \
go test ./...'
semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
14—✓ ✓
/bin/zsh -lc 'GOWORK=off GOPROXY=off go test ./...'
15—✓ ✓
/bin/zsh -lc 'git status --short -- audit service docs go.mod go.sum && \
git diff -- audit service docs/SUBOPTIMAL_TOOLS.md go.mod go.sum && \
cat audit/normalize.go && \
cat service/dispatch.go'
16—✓ ✓
/bin/zsh -lc 'git status --short -- audit service docs go.mod go.sum && \
git diff -- go.mod go.sum && \
cat audit/normalize.go && \
cat service/dispatch.go && \
cat audit/event.go && \
cat audit/sink.go'
17—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event = Normalize(event)\n\tm.Events = append(m.Events, event)\n\treturn nil",
  "file": "audit/sink.go",
  "symbol": "(*MemorySink).Write"
}
18—✓ ✓
/bin/zsh -lc 'git diff -- go.mod go.sum && \
git status --short -- go.mod go.sum'
19—✓ ✓
/bin/zsh -lc 'GOWORK=off GOPROXY=off go test ./...'
20—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
21—✓ ✓
/bin/zsh -lc 'rg -n "Classif|probe|Normalize|control|Kind" audit service metrics legacy docs && \
cat audit/summary.go && \
cat audit/normalize.go && \
cat audit/sink.go && \
git diff -- go.mod go.sum'
22—semedit/semantic_replace_body (✓ ✓)
{
  "body": "kind = Normalize(Event{Kind: kind}).Kind\n\tswitch kind {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
23—✓ ✓
/bin/zsh -lc 'git diff -- go.mod go.sum && \
git status --short -- go.mod go.sum'
24—✓ ✓
/bin/zsh -lc 'GOWORK=off GOPROXY=off go test ./...'
25—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
26—✓ ✓
/bin/zsh -lc 'cat service/dispatch.go && \
git diff -- go.mod go.sum && \
git status --short -- go.mod go.sum'
27—✓ ✓
/bin/zsh -lc 'GOWORK=off GOPROXY=off go test ./...'
28—semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "service"
}
29—✓ ✓
/bin/zsh -lc 'cat audit/normalize.go && \
cat audit/summary.go && \
cat service/dispatch.go && \
git diff -- go.mod go.sum && \
git status --short -- go.mod go.sum'
30—semedit/semantic_insert_function (✓ ✓)
{
  "file": "audit/normalize.go",
  "placement": "public_start",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
31—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event.Kind = NormalizeKind(event.Kind)\n\treturn event",
  "file": "audit/normalize.go",
  "symbol": "Normalize"
}
32—semedit/semantic_replace_body (✓ ✓)
{
  "body": "kind = NormalizeKind(kind)\n\tswitch kind {\n\tcase \"health\", \"probe\":\n\t\treturn \"control\"\n\tdefault:\n\t\treturn \"data\"\n\t}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
33—semedit/semantic_replace_body (✓ ✓)
{
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\n\treturn deliver(d.sink, event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
34—✓ ✓
/bin/zsh -lc 'go test ./...'
35—✓ ✓
/bin/zsh -lc "git diff -- go.mod go.sum && \
git status --short -- go.mod go.sum && \
sed -n '1,60p' audit/normalize.go && \
sed -n '1,45p' audit/summary.go && \
sed -n '1,50p' service/dispatch.go"
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 17 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'AGENTS.override.md' -g '*.go' -g 'README*' | head -200"
not published
2✓ ✓
/bin/zsh -lc "cat AGENTS.override.md && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g '*.md'"
not published
3✓ ✓
/bin/zsh -lc "cat docs/audit-sinks.md && \
sed -n '1,240p' audit/event.go && \
sed -n '1,260p' audit/fanout.go && \
sed -n '1,260p' audit/sink.go && \
sed -n '1,240p' audit/normalize.go && \
sed -n '1,220p' audit/transaction.go && \
rg -n \"probe|Probe|Kind|kind|audit\""
not published
4✓ ✓
/bin/zsh -lc 'cat service/dispatch.go service/replay.go audit/summary.go metrics/writer.go legacy/export.go journal/file.go && \
cat audit/event_test.go service/dispatch_test.go audit/summary_test.go metrics/writer_test.go legacy/export_test.go && \
git status --short --branch && \
cat go.mod'
not published
5✓ ✓
/bin/zsh -lc 'cat audit/transaction.go && \
git status --short audit service journal go.mod go.sum'
not published
6✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/sink.go audit/fanout.go audit/transaction.go audit/summary.go service/dispatch.go service/replay.go journal/file.go && \
go test ./...'
not published
7✓ ✓
/bin/zsh -lc 'git diff --check -- audit service journal && \
git status --short -- audit service journal go.mod go.sum && \
git diff -- audit service journal'
not published
8✓ ✓
/bin/zsh -lc "git rev-parse --show-toplevel && \
git status --short | head -30 && \
sed -n '1,120p' audit/normalize.go && \
git check-ignore -v audit/normalize.go"
not published
9✓ ✓
/bin/zsh -lc "sed -n '1,200p' audit/normalize.go && \
sed -n '1,160p' service/dispatch.go && \
sed -n '1,160p' audit/fanout.go && \
sed -n '1,200p' audit/transaction.go && \
sed -n '1,100p' audit/sink.go && \
sed -n '1,100p' audit/summary.go && \
sed -n '1,80p' journal/file.go && \
git status --short -- go.mod go.sum && \
go test ./..."
not published
10✓ ✓
/bin/zsh -lc 'cat audit/summary.go audit/normalize.go && \
git status --short -- go.mod go.sum'
not published
11✓ ✓
/bin/zsh -lc 'cat service/dispatch.go service/replay.go && \
cat audit/normalize.go && \
git status --short -- go.mod go.sum'
not published
12✓ ✓
/bin/zsh -lc 'gofmt -w audit/normalize.go audit/summary.go service/dispatch.go && \
go test ./... && \
git status --short -- go.mod go.sum'
not published

Target: codex/gpt-6-luna/xhigh

default prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-6-luna/xhigh
Prompt variantdefault
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
MetricVanilla (Small)MCP (Small)Δ (Small)Vanilla (Large)MCP (Large)Δ (Large)
Wall-Clock Latency128.71s162.37s+26.2%255.74s——
Process Start → First Event0.14s0.12s—0.56s——
First Event → First Tool Call6.83s8.95s—10.01s——
MCP Initialize → First Semantic Call——————
MCP Server Start → Initialize——————
Top-Level User Turns110%1——
Internal Tool Cycles1312-7.7%13——
Initial Load / Discovery Turns21-50.0%2——
MCP Discovery / Schema Turns00—0——
Tool Invocations (per run)1312-7.7%13——
Output Tokens60116684+11.2%9521——
Reasoning / Thinking Tokens41055223+27.2%6857——
Total Input Tokens204372283833+38.9%383051——
Cached Input Tokens185088257536+39.1%352768——
Uncached Input Tokens1928426297+36.4%30283——
Cost0.22090.2790+26.3%0.3686——
Cached vs Uncached Token Ratio9.60:19.79:1+2.0%11.65:1——
Oracle L1: Mutation PolicyPASSPASS—PASS——
Oracle L2: AST InvariantsPASSPASS—PASS——
Oracle L3: Clean BuildPASSPASS—PASS——
Oracle L4: Verification TestPASSPASS—PASS——
Semantic Tool Invocation Verified (per run)N/APASS—N/A——
Baseline vs Semedit Agentic in Small Context
  • Vanilla (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
  • Semedit MCP (Baseline vs Semedit Agentic in Small Context) Edit: File audit/normalize.go modified (2 lines -> 8 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'AGENTS*' -g 'PROJECT_BRIEF.md' -g 'README*' -g '*.go' -g 'Makefile' -g '*.md' | head -200"
✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'README*' -g 'AGENTS*' -g '*.go' -g '*.md' | head -200 && \
git status --short && \
rg -n \"Audit|audit|probe|Probe|event kind|EventKind|event_kind\" . --glob '"'!go.sum'"' --glob '"'!go.mod'"'"
2✓ ✓
/bin/zsh -lc 'cat docs/audit-sinks.md'
? ✗
/bin/zsh -lc "cat audit/event_test.go && \
cat audit/summary_test.go && \
cat service/dispatch_test.go && \
cat metrics/writer_test.go && \
cat legacy/export_test.go && \
rg --files -g 'PROJECT_BRIEF.md'"
3✓ ✓
/bin/zsh -lc "sed -n '1,240p' service/dispatch_test.go && \
sed -n '1,220p' audit/event_test.go && \
sed -n '1,220p' audit/summary.go"
✓ ✓
/bin/zsh -lc 'cat AGENTS.override.md && \
cat docs/audit-sinks.md && \
cat audit/event.go && \
cat audit/normalize.go && \
cat audit/sink.go && \
cat service/dispatch.go && \
cat audit/summary.go && \
cat metrics/writer.go && \
cat legacy/export.go'
4✓ ✓
/bin/zsh -lc "sed -n '1,240p' service/dispatch.go && \
sed -n '1,260p' audit/normalize.go && \
sed -n '1,220p' audit/event.go && \
sed -n '1,240p' audit/sink.go"
? ✗
/bin/zsh -lc "rg --files | sort | sed -n '1,160p' && \
sed -n '1,240p' Makefile 2>/dev/null && \
cat go.mod"
5✓ ✓
/bin/zsh -lc 'git status --short'
semedit/semantic_insert_function (✓ ✓)
{
  "auto_organize_imports": true,
  "file": "audit/normalize.go",
  "placement": "file_end",
  "source": "func NormalizeKind(kind string) string {\n\treturn strings.ToLower(strings.TrimSpace(kind))\n}"
}
6✓ ✓
/bin/zsh -lc "sed -n '1,220p' legacy/export.go && \
sed -n '1,260p' metrics/writer.go"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "event.Kind = audit.NormalizeKind(event.Kind)\nreturn d.sink.Write(event)",
  "file": "service/dispatch.go",
  "symbol": "(*Dispatcher).Record"
}
7✓ ✓
/bin/zsh -lc "sed -n '1,260p' audit/summary_test.go && \
sed -n '1,260p' legacy/export_test.go && \
sed -n '1,260p' metrics/writer_test.go"
semedit/semantic_replace_body (✓ ✓)
{
  "body": "writeEvent := audit.Sink.Write\nfor _, event := range events {\n\tevent.Kind = audit.NormalizeKind(event.Kind)\n\tif err := writeEvent(sink, event); err != nil {\n\t\treturn err\n\t}\n}\nreturn nil",
  "file": "service/dispatch.go",
  "symbol": "DispatchAll"
}
8✓ ✓
/bin/zsh -lc "rg -n 'Classify|Normalize|DispatchAll|NewDispatcher|\\.Record\\(|Kind|health|probe' --glob '"'!**/*_test.go'"' ."
semedit/semantic_replace_body (✓ ✓)
{
  "body": "switch NormalizeKind(kind) {\ncase \"health\", \"probe\":\n\treturn \"control\"\ndefault:\n\treturn \"data\"\n}",
  "file": "audit/summary.go",
  "symbol": "Classify"
}
9✓ ✓
/bin/zsh -lc "rg --files -g '"'!**/*_test.go'"' -g '"'!AGENTS.override.md'"'"
✓ ✓
/bin/zsh -lc 'cat go.mod && \
cat audit/normalize.go && \
cat service/dispatch.go && \
cat audit/summary.go && \
git diff -- audit/normalize.go service/dispatch.go audit/summary.go'
10✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os
import stat
import tempfile
import time

updates = {
    Path('audit/normalize.go'): '''// Package audit normalizes event kinds before audit delivery.
package audit

import \"strings\"

func NormalizeKind(kind string) string {
	return strings.ToLower(strings.Join(strings.Fields(kind), \" \"))
}
''',
    Path('audit/summary.go'): '''// Package audit groups delivery kinds for operational reporting.
package audit

func Classify(kind string) string {
	switch NormalizeKind(kind) {
	case \"health\", \"probe\":
		return \"control\"
	default:
		return \"data\"
	}
}
''',
    Path('service/dispatch.go'): '''// Package service coordinates application work with the configured audit sink.
package service

import \"example.com/auditapp/audit\"

type Dispatcher struct {
	sink audit.Sink
}

func NewDispatcher(sink audit.Sink) *Dispatcher {
	return &Dispatcher{sink: sink}
}

func (d *Dispatcher) Record(event audit.Event) error {
	event.Kind = audit.NormalizeKind(event.Kind)
	return d.sink.Write(event)
}

func DispatchAll(sink audit.Sink, events []audit.Event) error {
	for _, event := range events {
		event.Kind = audit.NormalizeKind(event.Kind)
		if err := sink.Write(event); err "'!= nil {
			return err
		}
	}
	return nil
}
'"''',
}

for path, content in updates.items():
    old_stat = path.stat()
    fd, temp_name = tempfile.mkstemp(prefix=f'.{path.name}.', dir=path.parent)
    try:
        with os.fdopen(fd, 'w', encoding='utf-8', newline='') as temp:
            temp.write(content)
            temp.flush()
            os.fsync(temp.fileno())
        os.chmod(temp_name, stat.S_IMODE(old_stat.st_mode))
        mtime_ns = max(time.time_ns(), old_stat.st_mtime_ns + 1)
        os.utime(temp_name, ns=(mtime_ns, mtime_ns))
        os.replace(temp_name, path)
        dir_fd = os.open(path.parent, os.O_RDONLY)
        try:
            os.fsync(dir_fd)
        finally:
            os.close(dir_fd)
    except BaseException:
        try:
            os.unlink(temp_name)
        except FileNotFoundError:
            pass
        raise
PY
gofmt -w audit/normalize.go audit/summary.go service/dispatch.go
git diff -- audit/normalize.go audit/summary.go service/dispatch.go"
? ✗
/bin/zsh -lc 'make check'
11✓ ✓
/bin/zsh -lc "sed -n '1,100p' audit/normalize.go && \
sed -n '1,120p' audit/summary.go && \
sed -n '1,120p' service/dispatch.go && \
git status --short -- audit/normalize.go audit/summary.go service/dispatch.go && \
git ls-files --stage -- audit/normalize.go audit/summary.go service/dispatch.go"
✓ ✓
/bin/zsh -lc 'go test ./...'
12? ✗
/bin/zsh -lc 'set -eu
before_mod=$(shasum -a 256 go.mod go.sum)
gofmt -d audit/normalize.go audit/summary.go service/dispatch.go
go test ./...
after_mod=$(shasum -a 256 go.mod go.sum)
if [ "$before_mod" != "$after_mod" ]; then
  printf '"'%s\\n' 'go.mod/go.sum changed during verification' >&2
  exit 1
fi
printf '%s\\n' 'go.mod and go.sum unchanged' "
semedit/semantic_verify (✓ ✓)
{
  "language": "go",
  "path": "."
}
13✓ ✓
/bin/zsh -lc 'set -eu
before_mod=$(shasum -a 256 go.mod)
if [ -e go.sum ]; then before_sum=present; else before_sum=absent; fi
gofmt -d audit/normalize.go audit/summary.go service/dispatch.go
go test ./...
after_mod=$(shasum -a 256 go.mod)
if [ -e go.sum ]; then after_sum=present; else after_sum=absent; fi
if [ "$before_mod" != "$after_mod" ] || \
[ "$before_sum" != "$after_sum" ]; then
  printf '"'%s\\n' 'protected module metadata changed during verification' >&2
  exit 1
fi
printf 'go.mod unchanged; go.sum remains %s\\n' \""'$after_sum"'
—
Baseline vs Semedit Agentic in Large Context
  • Vanilla (Baseline vs Semedit Agentic in Large Context) Edit: File audit/normalize.go modified (2 lines -> 15 lines)
#VanillaSemedit MCP
1✓ ✓
/bin/zsh -lc "pwd && \
rg --files -g 'PROJECT_BRIEF.md' -g 'AGENTS.md' -g 'README*' -g '*.go' -g 'Makefile' -g 'docs/**' | head -200"
not published
2✓ ✓
/bin/zsh -lc "rg --files -g '"'!*.sum'"' -g '"'!*.mod'"' && \
git status --short && \
sed -n '1,240p' docs/audit-sinks.md && \
sed -n '1,240p' audit/event.go && \
sed -n '1,260p' audit/normalize.go && \
sed -n '1,280p' audit/sink.go"
not published
3✓ ✓
/bin/zsh -lc "ls -la && \
sed -n '1,260p' audit/fanout.go && \
sed -n '1,260p' audit/transaction.go && \
sed -n '1,260p' audit/summary.go && \
sed -n '1,260p' service/dispatch.go && \
sed -n '1,240p' service/replay.go && \
sed -n '1,260p' metrics/metrics.go && \
sed -n '1,240p' metrics/writer.go && \
sed -n '1,260p' legacy/export.go"
not published
4✓ ✓
/bin/zsh -lc "sed -n '1,280p' audit/event_test.go && \
sed -n '1,280p' audit/summary_test.go && \
sed -n '1,280p' service/dispatch_test.go && \
sed -n '1,260p' metrics/writer_test.go && \
sed -n '1,260p' legacy/export_test.go && \
sed -n '1,260p' db/db.go && \
sed -n '1,260p' journal/file.go && \
sed -n '1,260p' models/models.go && \
cat go.mod"
not published
5✓ ✓
/bin/zsh -lc "python3 - <<'PY'
from pathlib import Path
import os, tempfile, time

root = Path.cwd()
changes = {
    'audit/normalize.go': '''// Package audit owns event normalization at its delivery boundary.
package audit

import (
\\t\"strings\"
)

func NormalizeKind(kind string) string {
\\treturn strings.Join(strings.Fields(strings.ToLower(kind)), \" \")
}

func NormalizeEvent(event Event) Event {
\\tevent.Kind = NormalizeKind(event.Kind)
\\treturn event
}
''',
    'audit/summary.go': '''// Package audit groups delivery kinds for operational reporting.
package audit

func Classify(kind string) string {
\\tswitch NormalizeKind(kind) {
\\tcase \"health\", \"probe\":
\\t\\treturn \"control\"
\\tdefault:
\\t\\treturn \"data\"
\\t}
}
''',
    'audit/sink.go': '''// Package audit exposes the established event sink contract and a memory implementation.
package audit

type Sink interface {
\\tWrite(Event) error
}

type TransactionalSink interface {
\\tSink
\\tBegin() error
\\tCommit() error
}

type MemorySink struct {
\\tEvents []Event
}

func NewMemorySink() *MemorySink {
\\treturn &MemorySink{}
}

func (m *MemorySink) Write(event Event) error {
\\tm.Events = append(m.Events, NormalizeEvent(event))
\\treturn nil
}
''',
    'audit/fanout.go': '''// FanoutSink delivers a normalized event to each configured audit destination.
package audit

type FanoutSink struct {
\\tFirst  Sink
\\tSecond Sink
}

func (f FanoutSink) Write(event Event) error {
\\tevent = NormalizeEvent(event)
\\tif err := f.First.Write(event); err "'!= nil {
'"\\t\\treturn err
\\t}
\\treturn f.Second.Write(event)
}
''',
    'audit/transaction.go': '''// BufferedSink exposes transactional delivery without owning the persistence protocol.
package audit

type BufferedSink struct {
\\tSink
\\tqueue []Event
}

func (b *BufferedSink) Begin() error {
\\tb.queue = b.queue[:0]
\\treturn nil
}

func (b *BufferedSink) Write(event Event) error {
\\tb.queue = append(b.queue, NormalizeEvent(event))
\\treturn nil
}

func (b *BufferedSink) Commit() error {
\\tfor _, event := range b.queue {
\\t\\tif err := b.Sink.Write(NormalizeEvent(event)); err "'!= nil {
'"\\t\\t\\treturn err
\\t\\t}
\\t}
\\treturn nil
}
''',
    'journal/file.go': '''// Package journal contains a separate audit implementation used by batch jobs.
package journal

import \"example.com/auditapp/audit\"

type JournalSink struct {
\\tEntries []audit.Event
}

func (j *JournalSink) Write(event audit.Event) error {
\\tj.Entries = append(j.Entries, audit.NormalizeEvent(event))
\\treturn nil
}

var _ audit.Sink = (*JournalSink)(nil)
''',
    'service/dispatch.go': '''// Package service coordinates application work with the configured audit sink.
package service

import \"example.com/auditapp/audit\"

type Dispatcher struct {
\\tsink audit.Sink
}

func NewDispatcher(sink audit.Sink) *Dispatcher {
\\treturn &Dispatcher{sink: sink}
}

func (d *Dispatcher) Record(event audit.Event) error {
\\treturn deliver(d.sink, event)
}

func DispatchAll(sink audit.Sink, events []audit.Event) error {
\\tfor _, event := range events {
\\t\\tif err := deliver(sink, event); err "'!= nil {
'"\\t\\t\\treturn err
\\t\\t}
\\t}
\\treturn nil
}

func deliver(sink audit.Sink, event audit.Event) error {
\\treturn sink.Write(audit.NormalizeEvent(event))
}
''',
    'service/replay.go': '''// Package service contains replay helpers for previously captured audit events.
package service

import \"example.com/auditapp/audit\"

func Replay(sink audit.Sink, events []audit.Event) error {
\\tfor _, event := range events {
\\t\\tif err := deliver(sink, event); err "'!= nil {
'"\\t\\t\\treturn err
\\t\\t}
\\t}
\\treturn nil
}
''',
    'docs/audit-sinks.md': '''# Audit delivery

The service records operational events at a package boundary so deployments can choose an appropriate destination. Event labels arrive from command-line flags, hooks, and external integrations, so audit delivery trims and lowercases them and collapses whitespace before sending them to a sink. Audit reporting classifies "'`health` and `probe` events as control traffic.

Metrics collection and archival export use separate protocols. Changes to the audit boundary should avoid coupling those components to event persistence details.
'"''',
}

for name, content in changes.items():
    path = root / name
    old_stat = path.stat()
    fd, temp_name = tempfile.mkstemp(prefix=f'.{path.name}.', dir=path.parent)
    try:
        with os.fdopen(fd, 'w', encoding='utf-8', newline='') as stream:
            stream.write(content)
            stream.flush()
            os.fsync(stream.fileno())
            next_mtime = max(time.time_ns(), old_stat.st_mtime_ns + 1)
            os.utime(stream.fileno(), ns=(old_stat.st_atime_ns, next_mtime))
            os.fsync(stream.fileno())
        os.replace(temp_name, path)
        dir_fd = os.open(path.parent, os.O_RDONLY)
        try:
            os.fsync(dir_fd)
        finally:
            os.close(dir_fd)
    except BaseException:
        try:
            os.unlink(temp_name)
        except FileNotFoundError:
            pass
        raise
PY"
not published
6✓ ✓
/bin/zsh -lc 'gofmt -d audit/normalize.go audit/summary.go audit/sink.go audit/fanout.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go && \
shasum -a 256 go.mod && \
test ! -e go.sum && \
printf '"'go.sum absent\\n'"
not published
7✓ ✓
/bin/zsh -lc 'go test ./...'
not published
8✓ ✓
/bin/zsh -lc 'go vet ./...'
not published
9✓ ✓
/bin/zsh -lc "sed -n '1,160p' audit/normalize.go && \
sed -n '1,120p' audit/summary.go && \
sed -n '1,180p' audit/transaction.go && \
sed -n '1,180p' service/dispatch.go && \
sed -n '1,120p' service/replay.go && \
sed -n '1,120p' journal/file.go && \
sed -n '1,120p' docs/audit-sinks.md"
not published
10✓ ✓
/bin/zsh -lc "rg -n \"func deliver|\\.Write\\(event|Classify\\(\" -g '*.go'"
not published
11✓ ✓
/bin/zsh -lc 'gofmt -d audit/normalize.go audit/summary.go audit/sink.go audit/fanout.go audit/transaction.go journal/file.go service/dispatch.go service/replay.go'
not published
12✓ ✓
/bin/zsh -lc 'shasum -a 256 go.mod'
not published
13✓ ✓
/bin/zsh -lc 'test ! -e go.sum'
not published

prefer_discover_semedit prompt · prescriptive MCP instructions · unspecified semedit restriction

SettingValue
Test casetask-11-mixed-sink-api-migration
Targetcodex/gpt-6-luna/xhigh
Prompt variantprefer_discover_semedit
MCP server instructionsprescriptive
Semedit arm restrictionunspecified
Run provenancebinary=44027cf7b57a0b4e
Fixturetestdata/bench/task_11_mixed_sink_api_migration.txtar

Vanilla LLM Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Do not use semantic editing MCP tools; use standard file editing. When done, output DONE.

Semedit MCP Prompt:

Do not edit tests. You are forbidden to modify protected files: “go.mod”, “go.sum”.

Before editing, inspect the complete available tool inventory, including deferred or lazy tools. If applicable semantic editing tools are callable, prefer them for source mutations. Audit event kinds may contain inconsistent whitespace and casing. Normalize them at the delivery boundary before persistence, and treat probe events as control traffic. Do not change the metrics or legacy export protocols. Preserve the module metadata and tests, and leave the workspace verified. Prefer using semantic editor operations if applicable. When done, output DONE.

Initial Workspace State (Before Edit)
// Package audit leaves room for normalization rules owned by the delivery boundary.
package audit
Benchmark run run-20260924-codex-descriptiveBenchmark run saluki-opencode-relay-20261011T095400Z