anoman
Anomaly Detection

Catch unusual AI behaviour before it becomes a problem.

Two-layer detection: Z-score/Welford sliding windows for fast signals, Isolation Forest per-customer models for subtle drift.

Detection layers

Statistical + ML anomaly detection

Layer 1 — Z-score / Welford

Online algorithm, no history required. 4 rules run on every request:

  • token_spike — tokens >> rolling average
  • request_burst — RPM spike
  • guardrail_storm — block rate spike
  • cost_outlier — cost >> session average

Layer 2 — Isolation Forest

Per-customer models, trained nightly from a 14-day analytics lookback (200-sample minimum). 8-dimensional feature vector:

total_tokenscost_usdrequest_rate_60stool_call_countguardrail_rate_300ssession_lengthprompt_len_charshour_of_day

Fail-soft design

Exceptions never block the completion pipeline. Anomaly scoring is fire-and-forget — a model load failure returns a degraded score, not a 500.

Inline scoring

ML score computed with a 5-minute process-local model cache. Models stored in the in-memory cache with 48h TTL, refreshed nightly by training job.

Ops alerts

Email alerts via Resend for anomalies, batch failures, and SLA breaches. Configurable threshold and recipient.

Dashboard integration

Acknowledge anomalies, link to trace for investigation. Severity cards in dashboard with open/high counts.

Detect unusual AI behaviour automatically.