The session db fixture now disposes the engine before deleting the file, since a module under a no-op db (tests/sdk, tests/flow) may have connected first; the sdk import tests forget the study packages they import; the supervision tests keep the real quarantine length so it cannot expire mid-assertion. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_013GAeg4Jo6xjZzjwy9QDWMQ