Feature: Populate default entries in System Message Database on first launch

Modifies `SystemMessageEntryPreferences.kt` to ensure that a predefined
set of placeholder `SystemMessageEntry` items are saved to the database
the first time the application loads these entries (typically on first app
install).

Changes include:
- Added a SharedPreferences flag `KEY_DEFAULT_DB_ENTRIES_POPULATED` to
  track if default entries have been populated.
- Updated `loadEntries()` to check this flag. If not set, three
  placeholder entries (with titles like "Example Task: Web Browsing"
  and guides containing "// TODO:" comments) are created and saved.
  The flag is then set to true.
- This ensures you have some initial examples in the database without
  affecting existing user-created entries on subsequent loads or app
  updates where the flag is already set.

This change does not affect the active system message or its default,
only the database of available system message entries.

Testing Caveat:
I was unable to complete automated testing of this change due to
persistent Android SDK configuration issues in the test environment.

Author: google-labs-jules[bot]

app/src/main/kotlin/com/google/ai/sample/util/SystemMessageEntryPreferences.kt

@@ -11,6 +11,7 @@ object SystemMessageEntryPreferences {
     private const val TAG = "SystemMessageEntryPrefs"
     private const val PREFS_NAME = "system_message_entry_prefs"
     private const val KEY_SYSTEM_MESSAGE_ENTRIES = "system_message_entries"
+    private const val KEY_DEFAULT_DB_ENTRIES_POPULATED = "default_db_entries_populated" // Added constant
 
     private fun getSharedPreferences(context: Context): SharedPreferences {
         return context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
@@ -31,7 +32,33 @@ object SystemMessageEntryPreferences {
 
     fun loadEntries(context: Context): List<SystemMessageEntry> {
         try {
-            val jsonString = getSharedPreferences(context).getString(KEY_SYSTEM_MESSAGE_ENTRIES, null)
+            val prefs = getSharedPreferences(context)
+            val defaultsPopulated = prefs.getBoolean(KEY_DEFAULT_DB_ENTRIES_POPULATED, false)
+
+            if (!defaultsPopulated) {
+                Log.d(TAG, "Default entries not populated. Populating now.")
+                val defaultEntries = listOf(
+                    SystemMessageEntry(
+                        title = "Example Task: Web Browsing",
+                        guide = "// TODO: Define a detailed guide for the AI on how to perform web browsing tasks. \n// Example: \"To search the web, first click on the search bar (element_id: 'search_bar'), then type your query using writeText('your query'), then click the search button (element_id: 'search_button').\""
+                    ),
+                    SystemMessageEntry(
+                        title = "Example Task: Sending an Email",
+                        guide = "// TODO: Provide step-by-step instructions for composing and sending an email. \n// Specify UI elements to interact with (e.g., compose button, recipient field, subject field, body field, send button).\""
+                    ),
+                    SystemMessageEntry(
+                        title = "General App Navigation Guide",
+                        guide = "// TODO: Describe common navigation patterns within this app or general Android OS that the AI should know. \n// Example: \"To go to settings, click on the 'Settings' icon. To return to the previous screen, use the back button.\""
+                    )
+                )
+                saveEntries(context, defaultEntries) // This saves them to KEY_SYSTEM_MESSAGE_ENTRIES
+                prefs.edit().putBoolean(KEY_DEFAULT_DB_ENTRIES_POPULATED, true).apply()
+                Log.d(TAG, "Populated and saved default database entries.")
+                // The logic will now fall through to load these just-saved entries.
+            }
+
+            // Existing logic to load entries from KEY_SYSTEM_MESSAGE_ENTRIES:
+            val jsonString = prefs.getString(KEY_SYSTEM_MESSAGE_ENTRIES, null)
             if (jsonString != null) {
                 // Log.v(TAG, "Loaded JSON: $jsonString") // Verbose
                 val loadedEntries = Json.decodeFromString(ListSerializer(SystemMessageEntry.serializer()), jsonString)