1 min lesson
Severity: how bad is the failure itself
Connect "How bad is the failure itself" to the decision you would make.
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Severity: how bad is the failure itselfone report, judged on its worst outcome
Severity describes the damage independent of how many people hit it. A single user losing uncommitted work is a serious event even if they're the only one. Rank failure classes from the one you'd interrupt someone over down to the one that can wait a sprint.
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Advanced table
Severity is graded on the worst plausible outcome, not the average one
- Tier
- S0 - Critical
- What it means
- Data loss, security exposure or full outage
- Cursor example
- An Agent edit silently overwrites unsaved files; a privacy-mode leak; backend down for all users
- Tier
- S1 - Major
- What it means
- Core workflow blocked, no workaround
- Cursor example
- Tab autocomplete returns nothing for everyone on the latest update; Agent loops and never completes
- Tier
- S2 - Degraded
- What it means
- Works but worse or a workaround exists
- Cursor example
- ⌘K latency doubled; codebase indexing is slow but eventually completes
- Tier
- S3 - Cosmetic
- What it means
- Annoyance, no functional loss
- Cursor example
- A misaligned icon in the model picker; a typo in a tooltip
| Tier | What it means | Cursor example |
|---|---|---|
| S0 - Critical | Data loss, security exposure or full outage | An Agent edit silently overwrites unsaved files; a privacy-mode leak; backend down for all users |
| S1 - Major | Core workflow blocked, no workaround | Tab autocomplete returns nothing for everyone on the latest update; Agent loops and never completes |
| S2 - Degraded | Works but worse or a workaround exists | ⌘K latency doubled; codebase indexing is slow but eventually completes |
| S3 - Cosmetic | Annoyance, no functional loss | A misaligned icon in the model picker; a typo in a tooltip |
Severity is graded on the worst plausible outcome, not the average one.
Watch out
Anything that can destroy a user's code or expose their data is S0 even if exactly one person reported it. Data loss has no quorum. If you find yourself debating whether a single-user data-loss bug is “really” urgent, you've already mis-graded it.