fix(release): fail closed on malformed WebUI metadata

tests/test_release_plan_guidance.py

@@ -108,6 +108,37 @@ class ReleasePlanGuidanceTests(unittest.TestCase):
                 self.assertIn("Repair the malformed TOML or JSON", finding.remediation)
                 self.assertEqual("resolve_release_gate", plan.recommended_action.id)
 
+    def test_malformed_webui_metadata_is_a_structured_blocker(self) -> None:
+        with tempfile.TemporaryDirectory() as temp_dir:
+            workspace = Path(temp_dir)
+            repo_path = workspace / "govoplan-files"
+            (repo_path / "webui").mkdir(parents=True)
+            (repo_path / "pyproject.toml").write_text(
+                '[project]\nname = "govoplan-files"\nversion = "1.2.4"\n',
+                encoding="utf-8",
+            )
+            (repo_path / "webui" / "package.json").write_text(
+                "{not-json\n", 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)
+        codes = {item.code for item in plan.gate_findings}
+        self.assertIn("repository_version_metadata_unreadable", codes)
+        finding = next(
+            item
+            for item in plan.gate_findings
+            if item.code == "release_webui_metadata_unreadable"
+        )
+        self.assertIn("JSONDecodeError", finding.message)
+        self.assertIn("Repair malformed 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")