# Month Proof

- **Event:** [Built with Opus 4.7: a Claude Code hackathon](https://cerebralvalley.ai/e/built-with-4-7-hackathon)
- **When:** Apr 21 at 12:00 PM – Apr 27 at 2:00 AM (EDT)
- **Where:** Online
- **Team:** [Can Soganci](https://cerebralvalley.ai/u/Janso)
- **GitHub:** https://github.com/jansoganci/iron-ledger.git
- **Demo video:** https://www.loom.com/share/93db0269afaa400aa612fe0311291094
- **Gallery:** https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery
- **Page:** https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery/149

Month Proof automates month-end close for US finance teams. Upload your financial Excel files → the agent reads them, compares to history, flags anomalies, writes a plain-language report, and sends it via email — all in under 2 minutes.

Finance teams spend 10-15 hours/month on manual variance analysis and narrative writing. Month Proof reduces that to zero human-hours for the first draft.

The system uses a 3-agent pipeline: Parser (column mapping with Haiku), Comparison (pure pandas variance calculation), and Interpreter (narrative generation with Opus 4.7). The critical innovation is the numeric guardrail: Claude never does math — all calculations happen in Python, and a verification layer ensures the narrative matches the pandas output within 2% tolerance. No report is saved until the guardrail passes.

Built with FastAPI, React, Supabase, and Claude Opus 4.7. Tested with real GL exports from NetSuite, QuickBooks, and manual consolidation scenarios. The entire codebase was developed using Claude Code as the primary development engine.

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Markdown version of https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery/149. Site index for agents: https://cerebralvalley.ai/llms.txt · full text: https://cerebralvalley.ai/llms-full.txt