feat(onboarding): add first-run membership activation

tests/test_appconfig.py

@@ -438,7 +438,10 @@ class AppConfigTests(TempDirMixin, unittest.TestCase):
             ai = appconfig.ai_config(config)
             self.assertEqual("cmhub", ai["backend"])
             self.assertEqual("cmhub", appconfig.ai_backend(config))
-            self.assertEqual("", appconfig.cmhub_config(config)["base_url"])
+            self.assertEqual(
+                appconfig.DEFAULT_CMHUB_BASE_URL,
+                appconfig.cmhub_config(config)["base_url"],
+            )
             self.assertEqual(
                 appconfig.CMHUB_CONNECT_TIMEOUT_DEFAULT,
                 appconfig.cmhub_config(config)["connect_timeout"],
@@ -480,6 +483,47 @@ class AppConfigTests(TempDirMixin, unittest.TestCase):
 
         self.assert_removed(temp_dir)
 
+    def test_default_gateway_url_and_first_use_state_preserve_existing_config(self):
+        with self.make_temp_dir() as temp_dir:
+            config_path = os.path.join(temp_dir, "config.json")
+            with open(config_path, "w", encoding="utf-8") as fh:
+                json.dump({"ai": {"cmhub": {"base_url": ""}}}, fh)
+
+            migrated = appconfig.load_config(config_path)
+
+            self.assertEqual(
+                appconfig.DEFAULT_CMHUB_BASE_URL,
+                appconfig.cmhub_config(migrated)["base_url"],
+            )
+            self.assertEqual("", appconfig.first_use_guide_state(migrated))
+
+            migrated["ai"]["cmhub"]["base_url"] = "https://gateway.example.com/api/v1"
+            saved = appconfig.save_config(migrated, path=config_path)
+            self.assertEqual(
+                "https://gateway.example.com",
+                appconfig.cmhub_config(saved)["base_url"],
+            )
+
+            pending = appconfig.save_first_use_guide_state(
+                "pending",
+                path=config_path,
+            )
+            self.assertEqual("pending", appconfig.first_use_guide_state(pending))
+            self.assertEqual(
+                "https://gateway.example.com",
+                appconfig.cmhub_config(pending)["base_url"],
+            )
+
+            dismissed = appconfig.save_first_use_guide_state(
+                "dismissed",
+                path=config_path,
+            )
+            self.assertEqual("dismissed", appconfig.first_use_guide_state(dismissed))
+            with self.assertRaises(appconfig.ConfigError):
+                appconfig.save_first_use_guide_state("unknown", path=config_path)
+
+        self.assert_removed(temp_dir)
+
     def test_subscription_notice_id_persists_without_credentials(self):
         with self.make_temp_dir() as temp_dir:
             config_path = os.path.join(temp_dir, "config.json")