codegraph-edit

name	codegraph-edit
description	Use this skill whenever you need to modify source files in a repo that has the `codegraph` CLI available. Apply changes by sending a unified diff to `codegraph patch` instead of using Edit/Write to rewrite file contents. Triggers when the user asks to "edit a file", "modify code", "apply a patch", "make a change to <symbol>", or any time you would otherwise reach for Edit/Write on source code.
version	0.1.0

codegraph-edit

When this skill is active, edit files by emitting a unified diff to codegraph patch, not by calling Edit or Write on source files. Patches are smaller, easier for the user to review, and the patch tool validates context lines so silent corruption fails loudly.

The rule

• DO produce a unified diff and apply it with codegraph patch <file> --diff <patchfile> (or via stdin).
• DO NOT use the Edit or Write tools on tracked source files. Reserve those for new non-source files (configs the patch tool can't reach, generated artifacts) or when the user explicitly asks for a full rewrite.
• DO NOT hand-edit by re-reading the whole file and calling Write with a near-identical body. That wastes tokens.

Producing a patch

Use standard unified-diff format with at least 3 lines of context:

--- a/src/server.rs
+++ b/src/server.rs
@@ -42,7 +42,7 @@
 fn handle_request(req: Request) -> Response {
     let id = req.id();
-    log::info!("got request {}", id);
+    log::debug!("got request {}", id);
     dispatch(req)
 }

Tips for keeping patches reliable:

• Pull the current source with codegraph snippet <file> <symbol> (or Read a small range) so the context lines match exactly — whitespace and trailing chars matter.
• Keep one logical change per patch. Multiple unrelated hunks across a file are fine; multiple unrelated changes should be separate patches so a failure leaves the rest unaffected.
• Re-index after large structural edits: codegraph index.

Applying a patch

Two equivalent ways:

# from a file
codegraph patch src/server.rs --diff /tmp/change.patch

# from stdin (preferred for ephemeral patches — no temp file)
printf '%s\n' "$DIFF" | codegraph patch src/server.rs

Always dry-run first when you're unsure the context will line up:

codegraph patch src/server.rs --diff /tmp/change.patch --check

--check parses and applies the diff in memory only. If it fails, fix the patch (usually stale context) and re-run before applying for real.

Output

Default output is JSON: { ok, file, hunks_applied, hunks_total, bytes_written, failure }. Pass --text for a one-line human summary. Exit code is non-zero on failure.

When the patch fails

• Re-read the target region with codegraph snippet and rebuild the diff against the actual current bytes.
• Don't fall back to Write to "just overwrite the file" — that loses concurrent edits and defeats the review benefit. Fix the patch.
• If the file is truly outside the working directory and you have permission, pass --allow-outside.

What still uses Edit/Write

• Creating brand-new files (codegraph patch is for modifying existing ones).
• Non-source artifacts where a diff is awkward (binary files, generated output).
• Cases where the user explicitly asks for a full-file rewrite.

For everything else: diff first, patch second, no direct writes.