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

tests/test_reviewer_fallback.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+import httpx
+
+from gitea_codex_bot.config import get_settings
+from gitea_codex_bot.services.repo_config import RepoReviewConfig
+from gitea_codex_bot.services.reviewer import _fallback_review, run_review_for_pr
+from gitea_codex_bot.types import ParsedCommand
+
+
+def test_fallback_review_surfaces_failure_reason() -> None:
+    result = _fallback_review({"diff": ""}, failure_reason="OpenAI API HTTP 401: invalid_api_key")
+
+    assert result["verdict"] == "has_issues"
+    assert result["summary"] == "OpenAI review failed. Error: OpenAI API HTTP 401: invalid_api_key"
+    assert result["findings"][0]["title"] == "OpenAI review request failed"
+    assert result["findings"][0]["body"] == "OpenAI API HTTP 401: invalid_api_key"
+
+
+def test_run_review_for_pr_uses_openai_http_error_in_fallback(monkeypatch) -> None:
+    def _fake_prepare(*_args, **_kwargs):
+        return "prompt", {"diff": "TODO: tighten validation"}, RepoReviewConfig()
+
+    def _raise_http_error(*_args, **_kwargs):
+        request = httpx.Request("POST", "https://api.openai.com/v1/responses")
+        response = httpx.Response(429, request=request, text='{"error":{"message":"rate_limited"}}')
+        raise httpx.HTTPStatusError("rate limited", request=request, response=response)
+
+    monkeypatch.setattr("gitea_codex_bot.services.reviewer.prepare_review_prompt", _fake_prepare)
+    monkeypatch.setattr("gitea_codex_bot.services.reviewer._call_openai_review", _raise_http_error)
+
+    settings = get_settings()
+    command = ParsedCommand(name="review", raw="@codex review")
+    result, _repo_cfg = run_review_for_pr(settings, object(), "acme/repo", 9, command)
+
+    assert result["summary"].startswith("OpenAI review failed. Error: OpenAI API HTTP 429:")
+    assert result["findings"][0]["title"] == "OpenAI review request failed"
+    assert "rate_limited" in result["findings"][0]["body"]
+    assert any(finding["title"] == "TODO marker in diff" for finding in result["findings"])