PR-first shipping + MERGEABLE gate + scheduled CI follow-ups + flaky-test diagnostic

CI policy + PR-first shipping workflow (jj + gh): Always run full CI suite on current HEAD; never gate unrelated PRs on each other. When local venv is heavily stale and pytest/mypy fail on import errors unrelated to the change, skip local execution and trust CI.

PR-FIRST SHIPPING (🔴): code fixes must ALWAYS result in a PR. Canonical workflow: (1) jj st + jj bookmark list pre-flight, (2) jj commit -m "<msg>" (NEVER interactive flags — hang in agent env), (3) verify bookmark at @-, (4) jj git push -b <name> (auto force-pushes on rewrite), (5) gh pr create --base main --head <name>. Never target immutable tracked bookmarks directly — use main@origin. Conventional commit style: imperative sentence-case "verb object" no trailing period.

MERGEABLE GATE: PR is mergeable only when test, lint, preview, Seer Code Review, AND darwin-arm64 + linux-arm64 + windows-x64 binary smokes are all green. Skipping checks (Hermes real ContextEngine ABC drift+conformance, Supabase Preview) are expected for code-only PRs and NOT blockers. Seer Code Review also commonly skipped (links to sentry.io) — treat as expected, not a blocker.

FLAKY-TEST DIAGNOSTIC (Aug 5 2026, reinforced): CI test [truncated — entry too long]