contracts(ccpa): v1.28.0 → v1.30.0 — register CCPA-018 + soft-deprecate CCPA-008 (#1735)

THREE changes bundled. v1.29.0 is SKIPPED — aprender#1705 (the original
v1.29.0 PR) auto-CLOSED when its base #1684 (v1.28.0) squash-merged
and deleted its feature branch. Companion-repo has been at the v1.29.0
contract YAML since M208 (pin.lock pointed at #1705's feature-branch
HEAD); this v1.30.0 upstream-flip realigns aprender main with companion's
contract content AND adds the M224/M230 deltas the operator-dispatched
Phase 5 Arena bench produced.

CHANGE (1): FALSIFY-CCPA-018 (arena_recovery_rate_bound) added to gate
registry at status: PROPOSED. Gate count: 17 → 18. Asserts
recovery_rate >= 0.5 AND oracle_passed_rate >= 0.3 on the M182 5-fixture
project-scale corpus driven via the live multi-turn Arena harness
(crates/ccpa-arena/, companion-repo M196-M210). Measures AGENT QUALITY
(does the agent recover when bash fails?), distinct from CCPA-016/017
which measure FUNCTIONAL OUTCOME. The asymmetric give-up-fast synthetic
fixture (100% pass BUT zero recovery → FAILS recovery floor) is the
canonical R3 distinguishing test.

CHANGE (2): FALSIFY-CCPA-008 (parity_score_bound) soft-deprecated to
status: ADVISORY in its summary. Gate STILL enforces aggregate >= 0.95,
per-fixture >= 0.80 on the 30 AUTHORED canonical fixtures — only the
INTERPRETATION flipped. Reframed from SYSTEM-LEVEL parity validation
("apr code matches claude on real engineering tasks") → METER VALIDATION
("the differ + scorer + per-tool equivalence rules correctly recognize
equivalent traces"). The system-level interpretation was empirically
FALSIFIED by the M224 Arena bench (see CHANGE (3)). Foreground parity
claims move to CCPA-016 (function-scale) + CCPA-017 (project-scale,
PROPOSED) + CCPA-018 (Arena recovery-rate, PROPOSED).

CHANGE (3): Records M224 first-operator-dispatched Phase 5 Arena bench
result in status_history. Operator ran scripts/phase-5-arena-bench.sh
against the M182 5-fixture project-scale corpus three times:
  - Run 1 (180s/turn) was noisy (6/10 timeout-killed)
  - Run 2 (600s/turn, 2400s wall) — clean teacher, 4/5 student
    apr-serve errors
  - Run 3 (post-aprender#1712 workaround M228) — 2/5 student cleanly
    completed 20 turns
All three: oracle_passed_rate = 0.0000 for BOTH systems. recovery_rate
= 0 for both. Verdict: evaluate_static_vs_arena(1.0, 0.0, ...) →
FalsifierOutcome::StaticFalsified.

Important nuance preserved in the status_history reason field: 0/5 for
BOTH systems means neither solves these specific tasks under this
harness — Axis 2 closure CEILING, not teacher-vs-student gap. The
Popperian comparator is deterministic; if a cleaner re-run (post
aprender#1712 fix) lifts recovery_rate or oracle_passed_rate, the
verdict revises automatically.

Cross-references in this PR:
- companion-repo M194-M210 = Phase 5 P5.1-P5.5 + coverage closure
- companion-repo M208 (PR #195) = the now-obsolete v1.29.0 mirror
- companion-repo M224 (PR #211) = evidence + headline revision
- companion-repo M226 (PR #213) = aprender#1712 + pkill workaround
- companion-repo M230 (PR #215) = soft-deprecation spec rewrite +
  new docs/specifications/static-fixture-deprecation.md (~140 lines)
- aprender#1712 = apr serve subprocess leak (root cause of the 3
  remaining student driver_errors in Run 3)

Tentative threshold values (CCPA-017: 0.3/0.3; CCPA-018: 0.5/0.3) WILL
be recalibrated after a cleaner re-run post-aprender#1712 upstream fix.

`pv validate contracts/claude-code-parity-apr-v1.yaml` → 0 errors, 0
warnings. Pure additive bump (CCPA-018) + interpretation amendment
(CCPA-008) + history record (M224). No schema change, no existing gate
behavior touched.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: noahgift