fix: CI file change detector to handle large PRs (#33092)

scripts/change_detector.py

@@ -63,7 +63,10 @@ def fetch_files_github_api(url: str):  # type: ignore
 
 def fetch_changed_files_pr(repo: str, pr_number: str) -> List[str]:
     """Fetches files changed in a PR using the GitHub API."""
-    url = f"https://api.github.com/repos/{repo}/pulls/{pr_number}/files"
+
+    # NOTE: limited to 100 files ideally should page-through but instead resorting
+    # to assuming we should trigger when 100 files have been touched
+    url = f"https://api.github.com/repos/{repo}/pulls/{pr_number}/files?per_page=100"
     files = fetch_files_github_api(url)
     return [file_info["filename"] for file_info in files]
 
@@ -103,7 +106,7 @@ def main(event_type: str, sha: str, repo: str) -> None:
     """Main function to check for file changes based on event context."""
     print("SHA:", sha)
     print("EVENT_TYPE", event_type)
-    files = None
+    files = []
     if event_type == "pull_request":
         pr_number = os.getenv("GITHUB_REF", "").split("/")[-2]
         if is_int(pr_number):
@@ -133,7 +136,10 @@ def main(event_type: str, sha: str, repo: str) -> None:
     output_path = os.getenv("GITHUB_OUTPUT") or "/tmp/GITHUB_OUTPUT.txt"  # noqa: S108
     with open(output_path, "a") as f:
         for check, changed in changes_detected.items():
-            if changed:
+            # NOTE: as noted above, we assume that if 100 files are touched, we should
+            # trigger all checks. This is a workaround for the GitHub API limit of 100
+            # files. Using >= 99 because off-by-one errors are not uncommon
+            if changed or len(files) >= 99:
                 print(f"{check}={str(changed).lower()}", file=f)
                 print(f"Triggering group: {check}")