Incident Response

Incident Response

Resolve production incidents quickly and safely. Under pressure, the instinct to jump to fixes causes more harm than good — this workflow keeps the response structured without slowing it down.

⛔ The Iron Law

Mitigate before you investigate; never declare resolved without verification evidence.

Stopping user impact and understanding the cause are separate jobs — don't trade the first for the second. And under pressure, a forward fix you haven't reviewed or verified often creates a second incident: prefer the blunt, reversible mitigation now and confirm recovery with data before declaring the incident over.

Step 1: Triage — Scope and Severity

Spend 2-3 minutes here, not more.

Determine blast radius:

• What is broken? (Specific feature, entire service, dependent services)
• Who is affected? (All users, subset, specific accounts, internal only)
• Is data being lost or corrupted? (If yes: severity immediately escalates)
• Is the issue getting worse over time or stable?

Classify severity:

• Sev1/P0: Complete service outage, data loss, security breach. All hands.
• Sev2/P1: Major feature down, significant user impact, degraded performance at scale.
• Sev3/P2: Minor feature broken, small user subset affected, workaround exists.

If you can't classify yet, treat it as Sev2 until proven otherwise.

Notify the right people now. Don't wait until you understand the problem. People need lead time to join.

See references/severity-levels.md for team-specific escalation paths.

Step 2: Mitigate First — Fix Later

The goal is to stop the bleeding, not to understand it. Mitigation and root cause analysis are separate phases.

Fastest mitigation options (try in order):

1. Feature flag off: If the broken code is behind a flag, disable it immediately
2. Rollback: If a recent deploy caused this, revert to the previous version
3. Traffic shed: Disable the specific endpoint or functionality that's failing
4. Circuit breaker / cache: Serve stale data while the live system is broken
5. Scale up: If it's a load issue, add capacity before investigating

Apply the first option that will work. Do not spend 20 minutes finding the perfect mitigation — apply the blunt one now, refine later.

Document each action with a timestamp as you go. This builds the post-mortem timeline automatically.

See references/communication-templates.md for status page and stakeholder update templates.

Step 3: Communicate

A brief status update every 15-30 minutes prevents stakeholders from escalating or interrupting responders. Use the template in references/communication-templates.md:

[TIME] Status: [Investigating / Mitigating / Recovering]
Impact: [What is broken, who is affected]
Last action: [What was just done]
Next action: [What's happening next]
ETA: [Best estimate or "unknown"]

Assign one person as the incident commander (coordinates response) and one as the communications lead (external updates). The same person should not do both under pressure.

Step 4: Investigate — Rapid Root Cause

Once mitigation is in place and user impact is reduced, find the root cause.

Apply the binary search from bug-investigating at high speed:

1. When did it start? Check deployment logs, config changes, dependency changes in the window before the incident.
2. What changed? Compare current state to last-known-good state.
3. Reproduce in isolation? Can you trigger the error on a single request/record?
4. Trace the error path: Follow the error from symptom back to cause using logs, traces, and metrics.

Time-box investigation phases: 15 minutes to identify the probable cause. If not found, escalate or bring in more people.

Step 5: Recover and Verify

Deploy the fix:

• For rollbacks: verify the previous version is clean, deploy, monitor for 10 minutes
• For forward fixes: code review is still required (even during incidents, a second set of eyes prevents making things worse)
• For config changes: change one variable at a time

Verify recovery:

• Error rate returns to baseline
• Latency returns to normal
• Affected functionality works end-to-end
• No secondary issues (cascading failures, queue backlogs)

Declare the incident resolved with a timestamp. Send a final status update.

Schedule the post-mortem within 48-72 hours while memory is fresh. Use the retrospective skill (incident post-mortem format).

Principles Applied

• KISS: Apply the simplest mitigation first. A blunt rollback that works beats an elegant fix that takes an hour.
• Blameless culture: Incidents are caused by systems, not people. Focus on what the system allowed, not who triggered it.
• Communication over silence: Even "we don't know yet" is better than silence. Stakeholders will escalate if they don't hear anything.
• Separate mitigation from investigation: Stopping user impact and understanding root cause are different work. Don't conflate them.

Rationalizations to reject

Time pressure makes these tempting. Reject them anyway.

Red flags — stop and correct course

• Debugging root cause while users are still impacted and no mitigation is live.
• Deploying a forward fix you haven't reviewed.
• Declaring resolved from a single metric or a quick glance.
• No timestamped action log being kept as you go.

Cross-Skill References

• rollback-strategy — design safe rollback plans before incidents happen
• bug-investigating — use for offline root cause analysis after mitigation
• retrospective — use the incident post-mortem format after the incident resolves
• deployment-checklist — gate future deploys to prevent recurrence