Agent: architect (architect)
Confidence: 58%
Cost: $1.7136
Duration: 4m 39s
Task ID: 4880184a-33d9-40d1-9f68-745c70977f52

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Summary

Implemented Page-Hinkley concept drift detection for agent performance metrics:

New: src/agents/drift-detector.ts — pure Page-Hinkley algorithm (~170 LOC) that detects gradual shifts in cost, confidence, and failure trends. Catches the “boiling frog” scenario where metrics drift slowly enough to stay within Z-score thresholds but the mean itself has shifted significantly.

Integration:

• getAgentTrends() now includes drift analysis alongside existing % change metrics
• get_agent_trends MCP tool displays drift section when detected
• New agent:drift:detected EventBus event for future alerting

Key design choice: Stateless recomputation from daily snapshots rather than persistent state — simpler, no stale data risk, and daily granularity is sufficient for agent performance monitoring.

Compilation passes. Commit: 5fc225e.

—HANDOFF—
TO: reviewer
INTENT: handoff
ARTIFACT_TYPE: code-change
SUMMARY: Page-Hinkley concept drift detector added to agent stats — review new drift-detector.ts and integration into stats-snapshot.ts