fix(release): harden review gate diagnostics

tests/test_release_plan_guidance.py

@@ -74,6 +74,40 @@ class ReleasePlanGuidanceTests(unittest.TestCase):
         self.assertEqual("preview_source_release", plan.recommended_action.id)
         self.assertIn("Preview Tag + Publish", plan.recommended_action.remediation)
 
+    def test_malformed_version_metadata_is_a_structured_blocker(self) -> None:
+        cases = (
+            ("package.json", "{not-json\n", "JSONDecodeError"),
+            ("pyproject.toml", "[project\n", "TOMLDecodeError"),
+        )
+        for relative_path, malformed, error_name in cases:
+            with self.subTest(relative_path=relative_path):
+                with tempfile.TemporaryDirectory() as temp_dir:
+                    workspace = Path(temp_dir)
+                    repo_path = workspace / "govoplan-files"
+                    repo_path.mkdir()
+                    (repo_path / "pyproject.toml").write_text(
+                        '[project]\nname = "govoplan-files"\nversion = "1.2.4"\n',
+                        encoding="utf-8",
+                    )
+                    (repo_path / relative_path).write_text(malformed, encoding="utf-8")
+
+                    plan = build_selective_release_plan(
+                        dashboard(workspace=workspace, version="1.2.4"),
+                        selected_repos=("govoplan-files",),
+                        repo_versions={"govoplan-files": "1.2.4"},
+                    )
+
+                self.assertEqual("blocked", plan.status)
+                finding = next(
+                    item
+                    for item in plan.gate_findings
+                    if item.code == "repository_version_metadata_unreadable"
+                )
+                self.assertEqual("govoplan-files", finding.repo)
+                self.assertIn(error_name, finding.message)
+                self.assertIn("Repair the malformed TOML or JSON", finding.remediation)
+                self.assertEqual("resolve_release_gate", plan.recommended_action.id)
+
     def test_webui_renders_recommendation_and_remediation(self) -> None:
         webui = (RELEASE_ROOT / "webui" / "index.html").read_text(encoding="utf-8")