feat: add 3-attempt circuit breaker to fix-renovate-tests agentic workflow

Author: jzbahrai

.github/workflows/fix-renovate-tests.md

@@ -56,6 +56,21 @@ then push those fixes back to the PR branch.
 
 ## Step-by-step instructions
 
+### 0. Circuit breaker — check attempt count
+
+Before doing anything else, count how many `[copilot-fix]` commits are already
+on this branch:
+
+```bash
+git log --oneline | grep -c '\[copilot-fix\]' || true
+```
+
+If the count is **3 or more**, the maximum number of automated fix attempts has
+been reached. Call `noop` immediately with the message:
+"Max fix attempts (3) reached. Human review required."
+
+Do NOT attempt any further fixes.
+
 ### 1. Identify the failing CI run
 
 Use the `agentic-workflows` tools to find the most recent failed workflow run
@@ -97,17 +112,21 @@ Use `cat`, `grep`, and `find` to explore the repository before editing.
 ### 5. Push your fixes
 
 After making all edits, push them to the PR branch using
-`push-to-pull-request-branch`.
+`push-to-pull-request-branch`. Use a commit message that includes `[copilot-fix]`
+so the circuit breaker in step 0 can count previous attempts, e.g.:
+`fix: update call sites for marshmallow 3.26.2 API change [copilot-fix]`
 
 Then remove the `renovate-fix-needed` label from the PR using `remove-labels`
 to signal that the fix has been applied. A separate workflow will detect the
 label removal and push an empty commit to re-trigger CI.
 
 ### 6. If no action is needed
 
-If the CI run is already green (the label was applied redundantly), or if you
-cannot determine a safe fix, call `noop` with a clear explanation.
+Call `noop` with a clear explanation if:
+- The CI run is already green (label applied redundantly)
+- You cannot determine a safe fix
+- The max attempt count was reached (step 0)
 
 **Never** guess at a fix or make changes you are not confident about.
-If you are unsure, call `noop` and leave a comment explaining what you found.
+If you are unsure, call `noop` and describe exactly what you found in the logs.