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Claude
03113312ad
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
69 lines
3.3 KiB
Markdown
69 lines
3.3 KiB
Markdown
# Phase 3 — playbook + proof
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**Exit criteria (SPEC §5): 3–5 public case studies · zero regressions
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shipped · playbook ≥6 classes · C/C++ targets · coz.**
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Phase 3 turns the trust layer and the agent loop from Phases 1–2 into
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*evidence*: verified optimization wins across the playbook and across
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languages, each one reproducible from a pinned corpus through the same
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gated pipeline, with every attempt — win or loss — in the append-only
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ledger.
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## What changed for Phase 3
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- **The trust layer went language-agnostic.** Build isolation moved from
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a cargo-specific `CARGO_TARGET_DIR` injection to an explicit `{out}`
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placeholder plus optional `sanitizer`/`sanitizer_binary` build
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templates (`crates/diff-test/src/target.rs`). A C/C++ target is now
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just a `target.toml` with `clang` commands. Proven zero-regression:
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tokei ran a full verdict through the refactored pipeline to a correct
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null result before any C target was added.
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- **A C target joined the roster** — cJSON (v1.7.19, MIT), with a
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trust-layer harness driver, a hermetic Unity/CTest gate, ASan+UBSan
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sanitizers, a deterministic pinned corpus, and its own A/A calibration
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(0/20 false positives, 20/20 injected-slowdown detections). CI gates
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it on every push.
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- **coz** is wired (`-DHOTPATH_COZ` progress point, `just coz`,
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`scripts/coz-*`); its apt runtime aborts in its own init on this
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container's glibc (documented in `results/cjson/coz/README.md`), so
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callgrind cache-sim is the working profiler.
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## Playbook classes exercised (≥6 required)
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| Class | Mechanism | Exercised on | Result |
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|---|---|---|---|
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| 1 | build config (LTO, codegen-units) | tokei | ✅ win (+10.4%) |
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| 2 | allocator swap (mimalloc) | comrak | needs-human-review (+4.6%) |
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| 3 | allocation churn | tokei, comrak, **cjson** | ✅ wins + one overturned |
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| 4 | data layout | comrak | attempted (rejected) |
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| 5 | algorithmic / redundant work | tokei ×3, **cjson** | ✅ wins |
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| 6 | SIMD / autovectorization | comrak, tokei | attempted (rejected) |
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Six classes exercised (1–6); class 5 and class 3 carry verified wins on
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both a Rust and a C target.
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## The case studies
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1. [`01-tokei-algorithmic-rust.md`](01-tokei-algorithmic-rust.md) —
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three independent CI-verified class-5 wins on a Rust code counter
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(~1.26× multiplied, stated as an approximation, not a measured
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figure), each unattended and audited.
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2. [`02-build-flags-and-allocators.md`](02-build-flags-and-allocators.md)
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— the cheap wins first: LTO (class 1) accepted, mimalloc (class 2)
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correctly held at needs-human-review.
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3. [`03-comrak-caught-false-accept.md`](03-comrak-caught-false-accept.md)
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— the pipeline auto-accepted a leaking teardown patch; the audit
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overturned it and hardened the pipeline. The most important study.
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4. [`04-cjson-c-target.md`](04-cjson-c-target.md) — the cross-language
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proof: a real sub-threshold win correctly rejected, then a byte-
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identical number-handling win accepted on the C target.
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## The through-line
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Every number here carries its 95% bootstrap CI and its workload. Every
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win survived byte-identical golden replay, a 10k-input differential
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fuzz, and sanitizers. Every rejection is a real mechanism that simply
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didn't clear the 2% CI-lower-bound bar — and it is in the ledger too,
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because a rejection is a complete, valid outcome. Nothing shipped that
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the pipeline couldn't prove.
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