docs: Clarify what a logically distinct commit is

"Keep logically distinct changes in separate commits" was being read as
split anything separable, which turns one piece of work into several
commits that only make sense read together.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

AGENTS.md

@@ -215,6 +215,11 @@ in churn.
   rationale is welcome when the subject alone does not provide enough context — keep it to the
   essentials rather than restating the diff. `Co-Authored-By` is the only trailer used here; do
   **not** add a `Claude-Session` link (or any other session/tooling trailer).
+- **"Logically distinct" means unrelated** — two different applications, two boxes that have nothing
+  to do with each other, a drive-by fix that happens to sit in a file you were editing anyway. One
+  piece of work stays in one commit even when it touches a config, several docs and a switch: if the
+  parts only make sense together, splitting them just makes each half unreviewable. Err towards one
+  commit and split when a reader would ask why two things arrived together.
 
 ## Documentation