gates: close the audit findings — enforce the gates the docs claimed

An adversarial audit found the enforcement story ahead of the code: gates
that were documented as hard gates were advisory, manual, or absent, and
several human-facing claims outran the machine record. This makes the
claims true.

High findings

- Differential fuzz was documentation, not enforcement: verdict hardcoded
  fuzz_iters=0 and diff-test hardcoded the gate to Skipped, while the case
  studies claimed 10k-iteration fuzz on the same wins. Fuzz is now a real
  pipeline gate (strict FUZZ-RESULT contract, executed count recorded), and
  it is inherently baseline-vs-candidate, so it runs on the accept path and
  reports Skipped in the standalone `just gates` flow. New hard rule: a
  machine `accepted` verdict is impossible unless the fuzz gate actually
  passed — otherwise it caps at needs-human-review.
- The agent's system prompt claimed FP/concurrency/unsafe patches were
  "routed to human review automatically". No such mechanism existed. Added
  a conservative lexical risk classifier (crates/verdict/src/risk.rs) that
  forces needs-human-review on any would-be accept carrying those signals;
  fp-tolerance equivalence always signals.
- The local verdict path ran agent-influenced code unsandboxed. It now runs
  under scripts/no-net.sh (network namespace) and fails closed. Upstream
  test suites are hash-verified against corpora/<t>/TESTSUITE.sha256 when
  present (scripts/pin-testsuite.sh generates them).

Also fixed, found while fixing the above

- The pipeline script's `set -e` was inert (brace group as the left operand
  of `&&`), so a failing candidate build did not abort the run and verdict
  could bench a stale binary. Now a scoped subshell whose status is branched
  on at top level.
- A wrapper that exits before exec'ing (no-net.sh refusing, bad wrapper path)
  stranded RUNNING.lock and left read_verdict polling forever. Failure
  accounting now lives outside the wrapper.
- harnessd's patch allowlist ignored git rename/copy headers and --no-prefix
  diffs; the rename-escape case is now a committed regression test.
- The workspace did not compile on Windows (ungated Unix APIs). cfg-gated;
  71 portable tests now run on both platforms.
- pin-check regenerated the corpus manifest instead of verifying it; it is
  now verify-only, with a deliberate `just pin-corpus` to re-pin.
- Max RSS is captured per run on Unix; PMU counters are opt-in diagnostics
  (compare --perf-stat), never part of the accept decision.

Docs now match the code, including what is NOT yet enforced: no target ships
a TESTSUITE.sha256 pin, no target declares [build].tsan, and matmul is not
wired to the fp-tolerance gate — each is stated as mechanized-but-inert
rather than done. Corrected the stale "33 ledger rows" (34), the playbook's
class-3 cJSON win (rejected), adversarial-review.md's sanitizer-separation
claim (five accepted rows carry sanitizers_clean=false), the unsupported
"40,000 requests" figure, and the blanket "historical rows record
fuzz_iters=0" (8 of 10; phase0-tokei-002/-003 record 4,332).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

results/phase4/README.md

@@ -36,9 +36,11 @@ numbers.
 ## The result (`phase4-cjson-service`, ledger)
 
 The accepted batch win `phase3-cjson-002` (+8.85% throughput) was
-measured as a **service under a 150 rps coordinated-omission-correct
+measured as a **service under a 150 rps-target coordinated-omission-correct
 replay**, baseline (pristine cJSON v1.7.19) vs candidate (the banked
-win), 20 interleaved rounds, server pinned, 40,000 requests, **0 drops**:
+win), 20 interleaved rounds, server pinned, **0 drops** — the ledger row
+records `sessions=20`, `rate_rps=150`, `drop_rate=0.0`; the total request
+count was **not machine-recorded** (see errata below):
 
 | metric | baseline | candidate | speedup | 95% CI |
 |---|---|---|---|---|
@@ -63,7 +65,10 @@ project in one line.
 ## The ROI, generated mechanically
 
 `just report phase4-cjson-service --service-json results/phase4/cjson-service.json`
-→ [`cjson-service-roi.md`](cjson-service-roi.md). On a 500-core fleet at
+→ [`cjson-service-roi.md`](cjson-service-roi.md). *(Note, 2026-07-13: the
+raw `cjson-service.json` was not preserved — see errata below — so this
+command is not reproducible as written; the generated report and the
+ledger row are the surviving evidence.)* On a 500-core fleet at
 $0.04/core-hour, the +6.2% p50 win returns **27.5 cores / $9,621 per
 year at the CI lower bound** (median 29.4 cores / $10,290) — and the
 report quotes the lower bound, because the point estimate is not a
@@ -79,3 +84,20 @@ that produced it, so the number survives hostile review.
   ledger row and the calibrated service JSON with no hand-editing;
   throughput→cores→dollars and latency percentiles, CIs and methodology
   inline.
+
+## Errata (2026-07-13)
+
+- **"40,000 requests" retracted.** This report originally stated the
+  replay comprised 40,000 requests. The `phase4-cjson-service` ledger row
+  records only `sessions=20`, `rate_rps=150`, and `drop_rate=0.0` — the
+  per-run request count was never machine-recorded, so the 40,000 figure
+  (an arithmetic reconstruction, not evidence) is withdrawn. The prose
+  above now states the ledger-backed facts only. The claimed result is
+  unaffected: p50 latency +6.2%, 95% CI [+5.8%, +7.2%], under the 150
+  rps-target CO-correct replay, 20 interleaved rounds, 0 drops.
+- **`results/phase4/cjson-service.json` was not preserved.** The
+  `.gitignore` rule `results/**/*.json` swept the raw service-latency
+  JSON that the report command consumes, so it no longer exists in the
+  repository. A `!results/phase4/*.json` carve-out has been added so
+  future service-mode evidence JSONs are committed alongside the
+  calibration JSONs.