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system-diff

system-diff draws a system from its code, and shows what each change does to it.

• The map: the parts of your system in columns, from what people use, through entry points, logic and data access, to stored data and outside systems, with the connections between them.
• The diff: what a commit, a branch or your uncommitted work adds, changes or removes in that structure. It comes as one sentence, an exact list and a picture of only what changed.

It reads code straight from git (no checkout), needs nothing but Python 3.11, and gives the same picture for the same code, byte for byte. So a part that did not change keeps its place, and a picture diff is a real diff.

Pages

• Getting started: install, the first map, the first diff
• Commands: every command and option
• Configuration: system-diff.toml, key by key
• How it reads code: what is observed and what is declared, and the limits
• Pictures: reading the map and the diff, and drawing your own pictures
• In pull requests: the GitHub workflow, and CI that keeps the README map current
• With AI coding agents: the hook, the live page, checkpoints and the MCP server
• Roadmap: what comes next