# Scar Tissue

- **Event:** [The Harness Engineering & Model Wrangling Hackathon](https://cerebralvalley.ai/e/mongodb-nyc-hackathon)
- **When:** Sat, Sep 26 at 9:00 AM – 10:00 PM (EDT)
- **Where:** New York, NY
- **Team:** [Woody Kim](https://cerebralvalley.ai/u/woody-kim)
- **GitHub:** https://github.com/the-woody-kim/scar-tissue
- **Demo video:** https://www.loom.com/share/7ca4cb6854ea49e09f5fea81ad3be1bd
- **Gallery:** https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery
- **Page:** https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/65

Scar Tissue: Every agent failure becomes a tested upgrade to its own harness.

An LLM agent takes a small grocery's orders in MongoDB Atlas. When a run breaks an invariant (the order API times out after saving, and the retry orders twice), the harness, with no human:

Turns the incident into test cases;
Recalls past incidents and their fixes with one $lookup;
Asks a model for three typed policy changes: rules, guardrails, context or tool access;
Drops any that name the incident, and tests the rest against a fixed evaluator it can't edit. Only a candidate that passes every case ships;
Writes the winner to Atlas, and the agent reloads it through a change stream, pinned by hash.

Agents that take real actions can't learn by trial and error in production. Scar Tissue makes the postmortem executable and tested.

https://scar-tissue-five.vercel.app/

## More from The Harness Engineering & Model Wrangling Hackathon

- [Team SG](https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/62)
- [Sightline](https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/63)
- [Cortex](https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/64)
- [Pregame](https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/66)
- [XChange](https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/67)
- [Chor](https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/68)

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Markdown version of https://cerebralvalley.ai/e/mongodb-nyc-hackathon/hackathon/gallery/65. Site index for agents: https://cerebralvalley.ai/llms.txt · full text: https://cerebralvalley.ai/llms-full.txt