Show HN: Sem – Semantic diffs and patches for Git

Git diffs are great for humans scanning line noise. But agents need to understand changes: "added function X", "renamed symbol Y", "moved block Z".

sem computes semantic diffs on top of your Git repo—no repo rewrite needed.

Repo: https://github.com/Ataraxy-Labs/sem

Key ideas:

Parses code to AST, computes tree‑edit ops (add/remove/move/change).

Outputs human‑/agent‑readable patches: "diff_sem" shows intent, not whitespace churn.

Applies deterministically via git apply --sem—survives formatting shifts or unrelated edits.

Use cases popping up:

Agent codemods: output semantic patches instead of brittle hunks.

Review tools: "explain this PR as semantic changes".

Stacked diffs / Graphite: semantic base for stacks.

Bulk refactors: apply "rename all X to Y" across noisy repos.