c4-diff
C4 Diff Diagrams
Turn a git change (two commit-ish references) into three C4 component diagrams — before, after, and a combined diff with a red/green/amber overlay — so a reviewer can validate the system-level impact of a change without reading every line.
This is review-grade documentation, not a modeling platform. Favor a small, honest, traceable diagram over an exhaustive one.
When this applies
Use this whenever the task involves comparing the structure of the code at two points in history: a PR, a branch vs its base, a single commit, or an arbitrary <base>..<head> range. If only one reference is given, diff it against its parent (<sha>~1) or the merge-base with the default branch — state which you chose.
Inputs
base— the "before" commit-ish (SHA, tag, branch). Required.head— the "after" commit-ish. Defaults toHEAD.out— output directory. Defaults to./artifacts.
Confirm these before doing work if any are ambiguous. Resolve each reference to its commit metadata so the reader gets the same context GitHub shows — short SHA, subject line, author, and date — not just an opaque hash: