fix: preserve eval evidence on graceful cancellation

[vriesd]

Summary

• Handle SIGINT/SIGTERM across startup, requests, scheduling, primary/reserve attempts, and host cleanup; stop accepting cancellation before immutable report publication.
• Preserve observed provider failures and completed evidence without inventing interrupted product outcomes. Share once-only cleanup, confirm process termination, and retain recoverable credential scratch on cleanup failure.
• Keep operator/budget stops nonqualifying, expose completion and failure origins in reports/triage, and document the strict frozen-candidate release sequence.
• Add isolated real-signal regressions with fake provider boundaries; no model calls or real credentials are used by these tests.

Validation

• Commit and clean-worktree push preflights passed. Optional gitleaks scanning was unavailable because gitleaks is not installed.
• bun run check: 790 passed, 1 skipped; typecheck, lint, build and release metadata checks passed.
• bun run replay: 13/13 cassettes matched.
• Prior Linux focused cancellation/qualification suite on the same implementation: 175 passed.
• Independent Flow implementation and final documentation reviews passed; both sessions are closed.

Limits And Release Status

• Failure snapshots can omit earlier/child-session token and cost usage. This remains explicitly documented partial accounting, not complete billing proof.
• Session v5, public tool inputs, package version (8.2.1), and exact-artifact qualification requirements are unchanged.
• Paid evals remain stopped. This PR contains no campaign evidence, credentials, Flow state, tag, or publication. A fresh campaign and exact-artifact canary still require separate approval after candidate validation and freezing.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-05T08:31:23.742186Z	2fb4bc3	PR opened

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