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Scans files being modified for incident annotations before touching them, surfacing prior postmortem learnings the model would otherwise ignore.
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Based on SOC occupation classification
Detects files that always change together, exposing hidden coupling that inflates Lead Time for Change and makes every PR bigger than it needs to be.
Generates a deployment-specific checklist before any code ships, covering rollout, monitoring, communication, and rollback. Directly reduces Change Failure Rate and Mean Time to Restore.
Requires a feature flag for any user-facing change, giving teams an instant kill switch without a deployment.
Identifies flaky tests in the affected test suite before shipping, because flaky tests kill Deployment Frequency by making CI untrustworthy.
Blocks shipping code where test coverage for changed files drops below threshold, and flags untested paths that directly raise Change Failure Rate.
Detects breaking changes to public APIs, interfaces, and exported symbols, and blocks shipping without a migration path.
| name | postmortem-check |
| description | Scans files being modified for incident annotations before touching them, surfacing prior postmortem learnings the model would otherwise ignore. |
| when_to_use | Apply automatically before modifying any existing file. |
When engineers survive a production incident, the good ones annotate the code. They leave comments like // INCIDENT-2024-03: this timeout must stay above 30s or the downstream service drops connections. These comments are the institutional memory of what went wrong and why certain decisions exist.
AI agents ignore these comments unless explicitly told to look for them. This skill makes looking for them mandatory.
Before modifying any existing file, scan it for annotations matching these patterns:
// INCIDENT: or // INCIDENT-# INCIDENT: or # INCIDENT-// POSTMORTEM: or /* POSTMORTEM# postmortem: or # POST-MORTEM// DO NOT CHANGE or // DO NOT REMOVE// WARNING: (especially near configuration, timeouts, retry logic, or connection pools)// FRAGILE: or // HACK: or // DANGER:// SEE RUNBOOK: or // SEE INCIDENT:If annotations are found, surface them before any code is written:
## Postmortem Check — Annotations Found
The following incident or warning annotations were found in files you are about to modify.
Read these before proceeding. They represent real production failures.
---
**File:** [path:line]
**Annotation:** [full comment text]
**Interpretation:** [one sentence explaining what constraint this implies for the current change]
---
[repeat for each annotation found]
### Impact on Current Task
[Does any annotation constrain or change what you were about to do?
If yes, describe how. If no, confirm explicitly that the change does not violate the annotated constraint.]
If no annotations are found, output a single line: Postmortem check: no incident annotations found in affected files.
If an annotation indicates that the change you are about to make was tried before and caused an incident, stop. Do not proceed without explicitly acknowledging the prior incident and explaining why the current change is different or safer.
Output:
## STOP — Prior Incident Annotation
A prior incident annotation at [file:line] directly constrains this change.
Annotation: [text]
Before proceeding, I need you to confirm one of the following:
1. This change is different from what caused the incident because: [reason]
2. The conditions that caused the incident no longer apply because: [reason]
3. You accept the risk and want to proceed anyway
I will not modify this code until one of the above is confirmed.
The worst production incidents are the ones that have happened before. A team that loses an engineer loses the memory of why a particular constant is 30 and not 5. The comment they left is the only thing standing between the next engineer (human or AI) and repeating the incident.
An AI that reads code without reading its warnings is an AI that will reopen closed incidents.