ChainReaction

ChainReaction tells you what a dependency upgrade will break before you merge it, and proves it. You type a decision like “upgrade numpy to 2.0” for any public Python repo. ChainReaction then: 1. finds and reads the official migration guide; 2. traces every affected import through the code; 3. Predicts the “domino chain” from the removed symbol up to the package root; 4. Runs the real test suite before and after the change to check the prediction; 5. Proposes fixes one layer at a time, keeping an edit only when its failure clears and nothing new breaks. The final report checks every claim it makes against the run’s own data. The core rule is that the model may only assert what a tool returned. Change items must quote their source word for word, and agent findings must cite the tool calls behind them. Predictions are compared with real tracebacks, and fixes with real test runs. Every model call, command and fetch is recorded, so the five presets replay offline with no key and no network. CI replays all five byte for byte on Ubuntu, macOS and Windows on every push.