fix: avoid red PR review runs without AI backend

Co-Authored-By: Codex <noreply@openai.com>

Author: Pigbibi

scripts/run_codex_pr_review.py

@@ -43,6 +43,10 @@
     "rate limit",
     "quota",
 )
+NO_REVIEW_BACKEND_CONFIGURED = (
+    "No Codex service URL or API key configured. "
+    "Set CODEX_AUDIT_SERVICE_URL, ANTHROPIC_API_KEY, or OPENAI_API_KEY."
+)
 
 # Risk → block mapping
 BLOCK_SEVERITIES = frozenset({"critical", "high"})
@@ -480,6 +484,10 @@ def _service_review_should_fallback(exc: ReviewError) -> bool:
     return any(signal in message for signal in CODEX_SERVICE_FALLBACK_SIGNALS)
 
 
+def _review_backend_is_unconfigured(exc: ReviewError) -> bool:
+    return str(exc).strip() == NO_REVIEW_BACKEND_CONFIGURED
+
+
 def run_codex_review_with_fallback(
     prompt: str,
     timeout_minutes: int,
@@ -570,10 +578,7 @@ def run_direct_api_review(prompt: str, complexity: str = "") -> str:
                 model=_direct_api_model_for_complexity(provider, normalized),
             )
 
-    raise ReviewError(
-        "No Codex service URL or API key configured. "
-        "Set CODEX_AUDIT_SERVICE_URL, ANTHROPIC_API_KEY, or OPENAI_API_KEY."
-    )
+    raise ReviewError(NO_REVIEW_BACKEND_CONFIGURED)
 
 
 def _run_anthropic_review(prompt: str, api_key: str, model: str = "") -> str:
@@ -985,7 +990,10 @@ def main() -> int:
             upsert_pr_comment(token, repo, pr_number, warning_body)
             return 0
 
-        # High-risk changes should not fail open on review infrastructure errors.
+        # Caller repositories may not have the central AI backend secrets configured.
+        # In that case, leave an explicit human-review note but do not create
+        # persistent red workflow runs. Other high-risk review infrastructure
+        # failures still fail closed.
         warning_body = (
             "<!-- codex-pr-review -->\n"
             "## 🤖 Codex PR Review\n\n"
@@ -994,6 +1002,9 @@ def main() -> int:
             "Please ensure a human reviewer checks this PR before merging.\n"
         )
         upsert_pr_comment(token, repo, pr_number, warning_body)
+        if _review_backend_is_unconfigured(exc):
+            print("::warning::Codex review backend is not configured; leaving human-review note without failing the workflow.")
+            return 0
         return 1
 
     print(f"Codex output: {len(output)} chars")

tests/test_run_codex_pr_review.py

@@ -124,6 +124,28 @@ def test_main_allows_low_risk_docs_on_review_infra_error(self) -> None:
 
         comment.assert_called_once()
 
+
+    def test_main_allows_unconfigured_backend_with_human_review_note(self) -> None:
+        with tempfile.TemporaryDirectory() as tmpdir:
+            event_path = self._write_event(tmpdir, ["scripts/run_codex_pr_review.py"])
+            env = {
+                "GH_TOKEN": "token",
+                "GITHUB_REPOSITORY": "org/repo",
+                "GITHUB_EVENT_PATH": event_path,
+                "GITHUB_EVENT_NAME": "pull_request",
+            }
+            with (
+                patch.dict(os.environ, env, clear=True),
+                patch("scripts.run_codex_pr_review.fetch_pr_files", return_value=[{"filename": "scripts/run_codex_pr_review.py"}]),
+                patch("scripts.run_codex_pr_review.fetch_pr_diff", return_value="diff --git a/scripts/run_codex_pr_review.py b/scripts/run_codex_pr_review.py"),
+                patch("scripts.run_codex_pr_review.run_codex_review_with_fallback", side_effect=ReviewError(run_codex_pr_review.NO_REVIEW_BACKEND_CONFIGURED)),
+                patch("scripts.run_codex_pr_review.upsert_pr_comment") as comment,
+            ):
+                self.assertEqual(run_codex_pr_review.main(), 0)
+
+        comment.assert_called_once()
+        self.assertIn("Human review required", comment.call_args.args[3])
+
     def test_service_timeout_does_not_fall_back_to_direct_api(self) -> None:
         with (
             patch.dict(os.environ, {"CODEX_AUDIT_SERVICE_URL": "https://service.example"}, clear=True),