Cost Tracking Use this skill to analyze Claude Code cost and usage history from the metrics log that ECC's hook writes. Where the data lives The tracker appends one JSON object per session-stop to . Each row is a cumulative snapshot for that session , so to total spend you take the latest row per and sum across sessions — summing every row multiply-counts. ECC also maintains internal per-session files under so runtime hooks can read the current session total without rescanning all history. Treat those files as a rebuildable cache; each snapshot stores a byte cursor so only newly appended rows…