Claude
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phase3-cjson-002 (class 5+3): stack-buffer number parsing + strtod round-trip replacing sscanf. +8.85% median, 95% CI [+7.5%, +10.0%] on the C target, banked. 100% audit: byte-identical golden replay, independent ASan+UBSan clean, 10k-input differential fuzz 0 divergences, patch bounds/free-gating verified by eye. - verdict: an infrastructure sanitizer-BUILD failure (missing runtime, broken toolchain) now caps the accept at needs-human-review and logs it, instead of crashing the verdict and losing a measured bench. - results/phase3/: four public case studies (tokei class-5 wins; build flags + allocators; the comrak caught false-accept; the cJSON cross-language proof) + README. Compound-speedup claim stated as an approximation, not a measured figure (CIs don't multiply). - .gitignore: cjson build-artifact dirs. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EcKPWQ3MQD4NdEHwar96u2
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Phase 3 — playbook + proof
Exit criteria (SPEC §5): 3–5 public case studies · zero regressions shipped · playbook ≥6 classes · C/C++ targets · coz.
Phase 3 turns the trust layer and the agent loop from Phases 1–2 into evidence: verified optimization wins across the playbook and across languages, each one reproducible from a pinned corpus through the same gated pipeline, with every attempt — win or loss — in the append-only ledger.
What changed for Phase 3
- The trust layer went language-agnostic. Build isolation moved from
a cargo-specific
CARGO_TARGET_DIRinjection to an explicit{out}placeholder plus optionalsanitizer/sanitizer_binarybuild templates (crates/diff-test/src/target.rs). A C/C++ target is now just atarget.tomlwithclangcommands. Proven zero-regression: tokei ran a full verdict through the refactored pipeline to a correct null result before any C target was added. - A C target joined the roster — cJSON (v1.7.19, MIT), with a trust-layer harness driver, a hermetic Unity/CTest gate, ASan+UBSan sanitizers, a deterministic pinned corpus, and its own A/A calibration (0/20 false positives, 20/20 injected-slowdown detections). CI gates it on every push.
- coz is wired (
-DHOTPATH_COZprogress point,just coz,scripts/coz-*); its apt runtime aborts in its own init on this container's glibc (documented inresults/cjson/coz/README.md), so callgrind cache-sim is the working profiler.
Playbook classes exercised (≥6 required)
| Class | Mechanism | Exercised on | Result |
|---|---|---|---|
| 1 | build config (LTO, codegen-units) | tokei | ✅ win (+10.4%) |
| 2 | allocator swap (mimalloc) | comrak | needs-human-review (+4.6%) |
| 3 | allocation churn | tokei, comrak, cjson | ✅ wins + one overturned |
| 4 | data layout | comrak | attempted (rejected) |
| 5 | algorithmic / redundant work | tokei ×3, cjson | ✅ wins |
| 6 | SIMD / autovectorization | comrak, tokei | attempted (rejected) |
Six classes exercised (1–6); class 5 and class 3 carry verified wins on both a Rust and a C target.
The case studies
01-tokei-algorithmic-rust.md— three independent CI-verified class-5 wins on a Rust code counter (~1.26× multiplied, stated as an approximation, not a measured figure), each unattended and audited.02-build-flags-and-allocators.md— the cheap wins first: LTO (class 1) accepted, mimalloc (class 2) correctly held at needs-human-review.03-comrak-caught-false-accept.md— the pipeline auto-accepted a leaking teardown patch; the audit overturned it and hardened the pipeline. The most important study.04-cjson-c-target.md— the cross-language proof: a real sub-threshold win correctly rejected, then a byte- identical number-handling win accepted on the C target.
The through-line
Every number here carries its 95% bootstrap CI and its workload. Every win survived byte-identical golden replay, a 10k-input differential fuzz, and sanitizers. Every rejection is a real mechanism that simply didn't clear the 2% CI-lower-bound bar — and it is in the ledger too, because a rejection is a complete, valid outcome. Nothing shipped that the pipeline couldn't prove.