fix(mosaic): bound promotion transport delivery

packages/mosaic/src/lease-broker/promotion_trigger_unittest.py

@@ -410,6 +410,33 @@ class PromotionCompleteTest(PromotionHookFixture):
         self.assertTrue(self.pending_file.exists())
         self.assertIn("ConnectionRefusedError", stderr)
 
+    def test_result_write_failure_exits_zero(self) -> None:
+        self.write_pending()
+        runner = mock.Mock(
+            return_value=self.completed(
+                {"stage": "promote_lease", "ok": True, "state": "VERIFIED"}
+            )
+        )
+
+        with mock.patch.object(self.complete, "write_result", side_effect=OSError("disk full")):
+            result, stderr = self.run_complete(runner)
+
+        self.assertEqual(result, 0)
+        self.assertIn("OSError", stderr)
+
+    def test_missing_lease_session_id_exits_zero(self) -> None:
+        self.write_pending()
+        environment = dict(self.environment)
+        del environment["MOSAIC_LEASE_SESSION_ID"]
+        runner = mock.Mock()
+        stderr = io.StringIO()
+
+        result = self.complete.main(environ=environment, stderr=stderr, run=runner)
+
+        self.assertEqual(result, 0)
+        runner.assert_not_called()
+        self.assertIn("KeyError", stderr.getvalue())
+
     def test_insecure_runtime_directory_mode_preserves_pending(self) -> None:
         self.write_pending(CHALLENGE)
         self.runtime_dir.chmod(0o755)