Cost Tracking

Use this skill to analyze Claude Code cost and usage history from the metrics log that ECC's stop:cost-tracker hook writes.

Where the data lives

The tracker appends one JSON object per session-stop to ~/.claude/metrics/costs.jsonl. Each row is a cumulative snapshot for that session, so to total spend you take the latest row per session_id and sum across sessions — summing every row multiply-counts.

Row schema: