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benbrownandClaude Opus 4.8
af3fc3dccd
The reusable artifact here was never the vendored targets — it is the discipline: prove equivalence, prove significance, or claim nothing. This packages it as a Claude Code skill usable from any repo. Two modes. `verify` works anywhere, on any two shell commands in any language: equivalence before timing -> A/A calibration -> interleaved A/B with a bootstrap CI -> a verdict decided by the CI lower bound, never the median. `attempt` drives the full in-repo loop (gates, pristine-baseline verdict, ledger row, ROI report). It drives the real bench-runner binary and refuses rather than degrade: on an unsupported host, or with no trust layer reachable, preflight stops and says so instead of falling back to a hand-rolled timing loop. A second copy of the statistics is a second thing that can lie. A refusal ends the claim, not the work. An adversarial review of the skill caught six high-severity defects, all fixed here — several of them the very errors the skill exists to prevent: - verify mode had no risk classification at all. bench-runner emits only accepted/rejected-bench; needs-human-review is minted by the in-repo verdict path, which verify does not run. A concurrency change with byte-identical output would have sailed through as "accepted". The skill now makes the agent the classifier and says so explicitly. - the accept template exposed `pin_prefix`, which is inert for compare/aa/calibrate (only `verdict` reads it) — an agent would have set it and reported pinning that never happened. Now documents wrapping both sides in taskset instead. - the equivalence gate compared stdout only, so two commands that write to stderr and a dist/ tree would "GOLDEN PASS" on two empty files. Now hashes stdout + stderr + exit code + artifact tree, and an empty diff over empty output is a failed gate, not a passed one. - nothing told the agent to build two coexisting immutable artifacts, so a `cargo run` baseline could rebuild from the patched tree mid-bench — the exact trap phase1-verdict-smoke-001 recorded. - service mode was documented as generic HTTP. It is not: the server must take <port> <doc> <iters>, print READY, and close the connection. A stock Express app hangs the harness forever. Contract now stated. - the CI refusal test could not pass: preflight also walks up from its own location, so running it in-place found this very repo. The test now copies the skill out of the tree first. CI job `skill-preflight` asserts the contract that matters — resolve when a trust layer is reachable, REFUSE when it is not, and work when consumed from another repo via PELTIER_HOME. It deliberately does not assert a statistical outcome: a shared runner is too noisy for that, which is precisely why the skill calibrates before it claims. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
105 lines
4.6 KiB
Markdown
105 lines
4.6 KiB
Markdown
# attempt — the full loop, inside a peltier checkout
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Profile → hypothesize → patch → gated verdict → ledger row. This mode only
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applies when you are working **inside a peltier checkout** on a target that has
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a `targets/<name>/target.toml`. Everywhere else, use
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[verify.md](verify.md).
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Requires Linux (harnessd uses Unix sockets and `setsid`; every gate shells
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through `sh`).
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## Before you touch anything
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**Read the ledger first.** It records every attempt ever made on this target,
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including the failures — which is exactly what stops you re-running a dead
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end:
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cargo run -p policy # ranks playbook classes by their evidence
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`policy` reads the ledger and ranks optimization classes by the Wilson lower
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bound of their shippable-win rate. It is **advisory** — a learned prior over
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the fixed cheapest-first order. The gates still decide every verdict.
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**Then respect the order.** Cheapest wins first: build flags → LTO → PGO →
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allocator swap → *then* code changes. Do not hand-write SIMD before trying
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`-O3`. The playbook (`playbook/`) has the preconditions and known risks for
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each class.
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## The boundary you may not cross
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The agent may modify **only** allowlisted paths under `targets/<name>/`.
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`crates/`, `config/`, `corpora/`, and the upstream test suites are read-only:
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the thing being measured does not get to grade itself. `harnessd` enforces
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this on every proposed diff (path allowlist over every diff header, including
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`rename`/`copy` — a patch that tries to escape is rejected, not sanitized).
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## Log the hypothesis *before* patching
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A hypothesis written after seeing the numbers is not a hypothesis. State what
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you think is slow, why, and what you expect the change to buy — then patch.
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## Run the gates
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just gates <target>
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Corpus pin → test-suite pin (when `corpora/<t>/TESTSUITE.sha256` exists) →
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upstream tests → golden replay. Note what this **does not** do: differential
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fuzz needs a pristine baseline to differ against, so it reports `Skipped` here
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and runs for real on the accept path below. `just gates` is a fast equivalence
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check, not a fuzz run — do not report it as one.
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## The verdict — the only thing that can accept a change
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just verdict <target> <candidate-bin> <run-id> <class> "<hypothesis>" "<hotspot>" \
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--patch-file <diff>
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This rebuilds a **pristine baseline** from the pinned upstream commit (not
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whatever is lying around in your tree), runs the full gate set against the
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candidate, benches interleaved A/B against that baseline, and writes one
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append-only ledger row with the verdict and the complete evidence.
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It will refuse to hand you an `accepted` unless:
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- the upstream test suite is green **and** golden replay is byte-identical (or
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within the target's declared FP tolerance);
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- the **differential-fuzz gate actually passed** — a real run reporting zero
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divergences. No fuzz run, no machine accept. Ever;
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- ASan/UBSan are clean (and TSan, when the target configures it);
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- the bootstrap 95% CI lower bound of the speedup clears the threshold in
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`config/accept.toml` (default 2%);
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- and a conservative lexical risk classifier finds **no** concurrency, unsafe,
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or floating-point signals in the patch. If it does, the verdict is capped at
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`needs-human-review` no matter how good the numbers are.
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Any of these failing produces a rejected row. **That is a complete, valid
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outcome** — the row is the deliverable. Write it and move on. Do not iterate on
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a rejected patch more than twice without a genuinely new hypothesis.
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## Report
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just report <run-id>
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Mechanically generates the ROI from the ledger row: throughput → cores →
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dollars, and/or latency percentiles — every figure with its CI, workload, and
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methodology printed inline. It flags any row that was not accepted, so a
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rejected attempt cannot be laundered into a dollar figure.
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## Unattended
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just agent-attempt <target> <run-id>
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Runs one full attempt behind the OS boundary: `harnessd` as the trusted uid on
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a Unix socket, the agent loop as an unprivileged user, the verdict pipeline
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wrapped in a network namespace (`scripts/no-net.sh`) that **fails closed** — if
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namespaces are unavailable it refuses to run rather than quietly running with
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the network up. `just isolation-check` verifies the boundary from the agent's
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side.
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## When the numbers are good and the change is scary
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FP-ordering, concurrency primitives, anything UB-adjacent: `needs-human-review`,
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always, regardless of the speedup. This is not a formality. The one false
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accept in peltier's history (`phase2-comrak-010`) passed its bench and was
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caught by a human audit afterwards — which is precisely why the sanitizer lane
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is now machine-enforced and why this rule does not bend.
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