Individual skill
cost-anomaly
MAD-based outlier detection on session spend: lists anomalous sessions with modified-z scores, with an optional --alert-on-outliers exit code for CI. Use when asked which individual session is the cost outlier; cost-burn covers the aggregate trend.
plugins/ruflo-cost-tracker/skills/cost-anomaly/SKILL.md
Source commit 722232566ad1fc4e73ba4fefc46d77d380ce61ba
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- Last checked
- Nov 6, 2026
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- Repository last updated
- Nov 7, 2026
- License
- MIT
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Read excerpt
Per-session outlier detection — the diagnostic counterpart to cost-burn's
aggregate-trend signal.
| Question | Skill |
|---|---|
| "Is the AGGREGATE rate accelerating?" | `cost-burn` |
| "Which SPECIFIC sessions are anomalous outliers?" | **`cost-anomaly`** ← this |
| "Could we have spent less in aggregate?" | `cost-counterfactual` |
| "When will we hit budget?" | `cost-projection` |
## Algorithm
Implementation: [`scripts/anomaly.mjs`](../../scripts/anomaly.mjs).
