Require verification after git commit execution

- update the git guide to require post-commit verification before reporting success
- document that commit verification must confirm git commit exited successfully, HEAD advanced, and the new commit appears in git log
- document that failed or non-created commits must be reported clearly instead of being claimed as successful

git-guide.md

@@ -25,6 +25,13 @@ This file records repo-specific git workflow preferences for `/home/aw/code/cds`
 - Do not treat a request such as "give me the git commit" or "make the commit" as approval by itself.
 - Only execute `git commit` after the user explicitly approves the displayed commit command.
 - If the user changes the requested commit message or scope after commands are shown, rebuild the proposal and wait for fresh approval.
+- After executing `git commit`, always verify that the commit actually succeeded before reporting success.
+- Verification must include checking that:
+  - `git commit` exited successfully
+  - `HEAD` advanced to a new commit
+  - the new commit appears in `git log --oneline -n 1`
+- Do not claim a commit was created unless that verification has been completed.
+- If `git commit` did not actually create a commit, report that clearly and leave the changes as uncommitted.
 
 ## Push Requests
 - When the user asks to push, use `git push -u origin main` by default unless the user explicitly asks for a different remote or branch.