Most teams running AI APIs don't know which project is eating their budget until the invoice lands. This workbook fixes that — no logging pipeline, no code changes needed. Track spend by model and project, get instant cost rollups via VLOOKUP against 19 pre-priced models (GPT-4o, Claude Sonnet, Gemini, Mistral — July 2026 pricing), and watch your MTD dashboard auto-flag when any project hits 80% of budget. Built for solo devs and small teams. Instant download — XLSX + PDF guide + README.