Rollback Contained in the Same Hour

Context

• A change threatened a long rollback window (regression risk on auth/session).
• Baseline rule: “Stop the line; fix in the same hour; no Plan B.”

Decision

• Pause new prompts, keep the change behind a flag, and diagnose inside the same iteration.
• Add the failing scenario to the baseline and tighten the prompt context before retrying.

Guardrails

• Living baseline update is mandatory after any failure.
• Traceability chain stays intact: roadmap node → prompt → failing evidence → fixed commit/CI.
• Health checks stay enabled during investigation to ensure the service never goes dark.

Outcome

• Regression was contained behind the flag; GitHub and existing flows stayed live.
• Baseline gained a new rule for auth/session changes (include health probes + UI walkthrough before merge).
• Recovery proof captured in the evidence timeline.

Lessons

• Short loops (1–2h) turn rollbacks into quick, documented recoveries.
• Baseline-first thinking prevents the same regression from resurfacing.
• Feature flags are the safety net when prompts misbehave.