diff --git a/CLAUDE.md b/CLAUDE.md
index 9ca72cf..9f33264 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -13,3 +13,14 @@ failures before treating the work as done:
 
 Do not consider a push complete until its CI run is green (or the failure is
 understood and explicitly accepted by the user).
+
+## PR title convention for CI-only PRs
+
+A PR whose diff is confined entirely to files under `.github/workflows/` gets a
+title starting with `CI: ` (capital, colon, space). A PR that's CI-*motivated*
+but also touches a real file elsewhere (a `bin/` script a workflow calls, a
+linter's `Makefile` wiring, a submodule, etc.) is NOT CI-only under this
+reading, even though CI is the reason it exists — don't stretch the prefix to
+cover those. Check the actual file list
+(`gh pr view <n> --json files --jq '.files[].path'`) before applying it, don't
+guess from the title/description alone.