RepoStory takes any public GitHub repository and separates its history into “milestones,” creating a readable project timeline that lets you put yourself in the developer’s shoes and understand their design process.
This was a two-person team project at Hack the North 2025, where it won a sponsor prize from Cerebras. I worked on the AI agent, the FastAPI backend, and the React/Next.js frontend.
The agent is built with openai-agents and powered by Cerebras for fast inference; it’s engineered to lazily collect data about commits in a milestone in steps of increasing complexity, then use that data to choose which files to actually examine. For example, it’s obviously more likely to query the diff for project.py than node_modules. We stream the agent’s progress to the frontend, so users can watch tool calls and see the timeline generate in real time.
On the Git side, performance was a priority. It’s not feasible to just send everything to the agent, so we only fetch tree objects on initialization, never blobs, and minimize expensive diff operations. To select meaningful milestone boundaries, we use a heuristic that measures “work done” between commits, then used Git’s bisect utility to binary search for the commit that crosses a threshold.
Find the project on GitHub.
