Tyrell Build 13 release rereview v4

Completed an independent read-only release gate against the frozen Build 13 revision; the requested v3 blockers are closed, but unexpected inner helper exit statuses remain fail-open, so the verdict is NO-GO.

• Scope: local rdmsm4x review; no remote host, application runtime, signing identity, or deployment changed.
• Source reviewed: /Users/richh/dev/_worktrees/tyrell-build18-chat-catalog-20260902 at base HEAD 42277bcf045b3e9d6b93ac2ab98355db08c89d56, dirty diff SHA-256 21b3b0d1336c0d8bb2e0e26cd6c1a497cd580c8fe173c9ea664273cbb27a3cd3.
• File added: /Users/richh/dev/_handoff/tyrell-build13-release-rereview-v4-20260903.md (SHA-256 bb8e7145d8717536d9080383f1e8ed1b28ab6bdd8587e813e14c619d69755e42).
• Project files touched by reviewer: none.
• Validation: syntax over all project scripts/libraries/script tests; all eight release contracts; headless debug build and lifecycle checks; git diff --check; injected candidate-survivor rejection. All passed.
• Finding: tyrell_app_nested_recovery_disposition reports verified for all nonzero inner statuses except 5 when app recovery succeeds, including signal statuses 130, 137, and 143. Interrupted helper mutation is therefore capable of being mislabeled as verified rollback.
• Undo: remove only the added v4 handoff report and this changelog file. No source/runtime rollback is needed.
• Outstanding owner action: whitelist only explicitly safe inner statuses, treat unknown/signal exits as incomplete with outer exit 5, add fault cases, and request one final independent review before canary.
• Apple Notes: pending because the reviewer runs under the Background launchd manager and cannot send GUI AppleEvents safely.