refactor: enhance fallback review to include detailed failure reasons from OpenAI API

src/gitea_codex_bot/services/reviewer.py

@@ -166,8 +166,42 @@ def _call_openai_review(settings: Settings, prompt: str) -> dict[str, Any]:
     raise ReviewError("OpenAI response did not contain JSON output text.")
 
 
-def _fallback_review(diff_context: dict[str, Any]) -> dict[str, Any]:
-    findings = []
+def _summarize_openai_failure(exc: Exception) -> str:
+    if isinstance(exc, httpx.HTTPStatusError):
+        status = exc.response.status_code
+        response_text = exc.response.text.strip()
+        if response_text:
+            compact = " ".join(response_text.split())
+            if len(compact) > 400:
+                compact = f"{compact[:400]}..."
+            return f"OpenAI API HTTP {status}: {compact}"
+        return f"OpenAI API HTTP {status}."
+    if isinstance(exc, httpx.TimeoutException):
+        return "OpenAI API request timed out."
+    message = str(exc).strip()
+    if message:
+        return message
+    return f"{exc.__class__.__name__} (no details)"
+
+
+def _fallback_review(diff_context: dict[str, Any], *, failure_reason: str | None = None) -> dict[str, Any]:
+    findings: list[dict[str, Any]] = []
+    summary = "Fallback analysis was used because OpenAI review was unavailable."
+
+    if failure_reason:
+        summary = f"OpenAI review failed. Error: {failure_reason}"
+        findings.append(
+            {
+                "severity": "high",
+                "file": "unknown",
+                "line_start": 1,
+                "line_end": 1,
+                "title": "OpenAI review request failed",
+                "body": failure_reason,
+                "suggestion": "Fix API/auth/network issues and rerun @codex review.",
+            }
+        )
+
     if "TODO" in diff_context["diff"]:
         findings.append(
             {
@@ -183,7 +217,7 @@ def _fallback_review(diff_context: dict[str, Any]) -> dict[str, Any]:
     return {
         "verdict": "correct" if not findings else "has_issues",
         "confidence": 0.4 if not findings else 0.6,
-        "summary": "Fallback analysis was used because OpenAI review was unavailable.",
+        "summary": summary,
         "findings": findings,
     }
 
@@ -198,8 +232,8 @@ def run_review_for_pr(
     prompt, diff_context, repo_cfg = prepare_review_prompt(settings, gitea, repo, pr_number, command)
     try:
         result = _call_openai_review(settings, prompt)
-    except Exception:
-        result = _fallback_review(diff_context)
+    except Exception as exc:
+        result = _fallback_review(diff_context, failure_reason=_summarize_openai_failure(exc))
     return normalize_review_result(result), repo_cfg