Reject deploy error URLs in builder

tests/test_builder_prompt.py

@@ -70,6 +70,39 @@ class FakeGraph:
         }
 
 
+class FakePlanLimitGraph:
+    async def astream_events(self, *_args, **_kwargs):
+        yield {
+            "event": "on_tool_end",
+            "name": "cp_deploy_tarball",
+            "data": {
+                "output": {
+                    "error": "cp 402",
+                    "detail": (
+                        '{"detail":{"error":"plan_limit","feature":"agents",'
+                        '"upgrade_url":"https://app.a2acloud.io/billing"}}'
+                    ),
+                }
+            },
+        }
+        yield {
+            "event": "on_chain_end",
+            "parent_ids": [],
+            "data": {
+                "output": {
+                    "messages": [
+                        {
+                            "content": (
+                                "Deployment failed. Upgrade: "
+                                "https://app.a2acloud.io/billing"
+                            )
+                        }
+                    ]
+                }
+            },
+        }
+
+
 class AgentBuilderBuildTests(unittest.IsolatedAsyncioTestCase):
     async def test_build_captures_nested_graph_state_and_deployed_url(self) -> None:
         ctx = FakeRunContext()
@@ -87,6 +120,22 @@ class AgentBuilderBuildTests(unittest.IsolatedAsyncioTestCase):
         self.assertIn("Deployed at https://generated-agent.a2acloud.io", result["reply"])
         self.assertIn("deployed: https://generated-agent.a2acloud.io", ctx.progress)
 
+    async def test_build_does_not_treat_billing_url_as_deployed_agent(self) -> None:
+        ctx = FakeRunContext()
+
+        with patch("agent.build_agent_builder", return_value=FakePlanLimitGraph()):
+            result = await AgentBuilder().build(
+                ctx,
+                name="generated-agent",
+                prompt="make a test agent",
+                public=False,
+            )
+
+        self.assertEqual(result["ok"], False)
+        self.assertNotIn("url", result)
+        self.assertIn("no live URL was found", result["warning"])
+        self.assertNotIn("deployed: https://app.a2acloud.io/billing", ctx.progress)
+
 
 class BuilderPromptTests(unittest.TestCase):
     def test_outer_agent_uses_500_recursion_limit(self) -> None: