Spinning up a throwaway Postgres via Docker in test.sh forced Docker onto every local dev machine — that's the job of the dedicated test system, not local iteration. test.sh now fails loudly if DATABASE_URL is unset instead, so the append-only guarantee still can't be silently skipped on the release path, without assuming Docker locally. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>