feat: Require account ID configuration for sample app

Move account ID from hardcoded value to local.properties configuration.
The sample app now requires maxmind.account.id to be set, showing an
error message if not configured.

Configuration in local.properties:
  maxmind.account.id=123456

This ensures developers use their own account ID rather than a demo value.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: oschwald

SETUP.md

@@ -188,17 +188,32 @@ device-android/
 └── README.md            # Main documentation
 ```
 
-## Local Development Server
+## Sample App Configuration
 
-The sample app can be configured to connect to a local development server
-instead of the production MaxMind servers. This is useful for testing the SDK
-against a local backend.
+The sample app requires configuration via `local.properties` (gitignored).
 
-### Quick Start
+### Required Configuration
+
+Add your MaxMind account ID to `local.properties`:
+
+```properties
+maxmind.account.id=123456
+```
+
+Without this, the sample app will show an error when you try to initialize the
+SDK.
+
+### Local Development Server
+
+The sample app can optionally connect to a local development server instead of
+the production MaxMind servers.
+
+#### Quick Start
 
 1. **Add to `local.properties`**:
 
    ```properties
+   maxmind.account.id=123456
    debug.server.url=https://localhost:8443
    debug.ca.cert=/path/to/your/ca.crt
    ```
@@ -219,13 +234,14 @@ against a local backend.
 
 Add these to `local.properties` (gitignored):
 
-| Property           | Description                                  |
-| ------------------ | -------------------------------------------- |
-| `debug.server.url` | Server URL (e.g., `https://localhost:8443`)  |
-| `debug.ca.cert`    | Path to CA certificate for self-signed HTTPS |
+| Property             | Required | Description                                  |
+| -------------------- | -------- | -------------------------------------------- |
+| `maxmind.account.id` | Yes      | Your MaxMind account ID                      |
+| `debug.server.url`   | No       | Server URL (e.g., `https://localhost:8443`)  |
+| `debug.ca.cert`      | No       | Path to CA certificate for self-signed HTTPS |
 
-Both properties are optional. Without them, the sample app connects to
-production MaxMind servers.
+Without the optional debug properties, the sample app connects to production
+MaxMind servers.
 
 ### ADB Reverse Port Forwarding
 

sample/build.gradle.kts

@@ -16,6 +16,7 @@ if (localPropertiesFile.exists()) {
 }
 val debugServerUrl = localProperties.getProperty("debug.server.url", "")
 val debugCaCertPath = localProperties.getProperty("debug.ca.cert", "")
+val accountId = localProperties.getProperty("maxmind.account.id", "0")
 
 android {
     namespace = "com.maxmind.device.sample"
@@ -40,6 +41,7 @@ android {
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
 
         buildConfigField("String", "DEBUG_SERVER_URL", "\"$debugServerUrl\"")
+        buildConfigField("int", "MAXMIND_ACCOUNT_ID", accountId)
     }
 
     buildTypes {

sample/src/main/java/com/maxmind/device/sample/MainActivity.kt

@@ -67,11 +67,18 @@ class MainActivity : AppCompatActivity() {
                 return
             }
 
+            // Check that account ID is configured
+            if (BuildConfig.MAXMIND_ACCOUNT_ID == 0) {
+                val errorMsg = "Account ID not configured. Add maxmind.account.id to local.properties"
+                appendLog("✗ $errorMsg")
+                showMessage(errorMsg)
+                return
+            }
+
             // Create SDK configuration
-            // Note: Replace with your actual MaxMind account ID
             val configBuilder =
                 SdkConfig
-                    .Builder(123456) // Demo account ID - replace with real one
+                    .Builder(BuildConfig.MAXMIND_ACCOUNT_ID)
                     .enableLogging(true)
 
             // Use debug server URL if configured in local.properties