document backend switching

README.md

@@ -79,7 +79,7 @@ npm run dev
 
 The web app starts at `http://localhost:3000`.
 
-### 5. Run the desktop client (optional)
+### 5. Run the desktop client
 
 ```sh
 cd desktop
@@ -87,10 +87,61 @@ cp connectionpetstore.properties.example connectionpetstore.properties
 mvn javafx:run
 ```
 
-### 6. Run the Android app (optional)
+### 6. Run the Android app
 
 Open `android/` in Android Studio and run on an emulator or device.
 
+## Switching Between Azure and Local Backend
+
+Each client reads the backend URL from a config file. To point a client at the
+hosted Azure backend versus a local one, flip the commented lines.
+
+### Web
+
+Edit `web/.env.local`:
+
+```
+# Local
+BACKEND_URL=http://localhost:8080
+#BACKEND_URL=https://petshop-backend.nicepond-c7280126.westus2.azurecontainerapps.io
+
+# Azure
+#BACKEND_URL=http://localhost:8080
+BACKEND_URL=https://petshop-backend.nicepond-c7280126.westus2.azurecontainerapps.io
+```
+
+Restart the dev server after changing.
+
+### Desktop
+
+Edit `desktop/src/main/resources/connectionpetstore.properties`:
+
+```
+# Local
+api.baseUrl=http://localhost:8080
+#api.baseUrl=https://petshop-backend.nicepond-c7280126.westus2.azurecontainerapps.io
+
+# Azure
+#api.baseUrl=http://localhost:8080
+api.baseUrl=https://petshop-backend.nicepond-c7280126.westus2.azurecontainerapps.io
+```
+
+### Android
+
+Edit `android/local.properties`:
+
+```properties
+# Local (emulator — 10.0.2.2 maps to host's localhost)
+petstore.backend.emulatorUrl=http\://10.0.2.2\:8080/
+petstore.backend.deviceUrl=http\://192.168.x.x\:8080/
+
+# Azure
+petstore.backend.emulatorUrl=https\://petshop-backend.nicepond-c7280126.westus2.azurecontainerapps.io/
+petstore.backend.deviceUrl=https\://petshop-backend.nicepond-c7280126.westus2.azurecontainerapps.io/
+```
+
+Sync Gradle and re-run the app.
+
 ## API
 
 A Postman collection is available at `backend/postman/`. Key endpoint groups: