Feature: Reorder AI prompt components

Modifies PhotoReasoningViewModel.kt to change the order in which
information is sent to the Generative AI model. The new order is:
1. System Message (as the first message in the chat history with "user" role)
2. Chat History (previous user/model messages)
3. Current User Input

Previously, the system message was prepended to the current user input.
This change makes the system message a more distinct initial instruction
for the AI model.

Changes include:
- Modified `rebuildChatHistory()` to prepend the system message.
- Modified `clearChatHistory()` to initialize with the system message.
- Removed system message prepending from the `reason()` method.

Note: The `com.google.ai.client.generativeai` SDK (version 0.9.0)
used in this application is deprecated. You should consider migrating
to the recommended Firebase SDK for future development and potentially
more robust support for system instructions.

Automated testing of this change could not be completed due to
persistent Android SDK configuration issues in the test environment.

Author: google-labs-jules[bot]

app/build.gradle.kts

@@ -3,7 +3,7 @@
 plugins {
     id("com.android.application")
     id("org.jetbrains.kotlin.android")
-    id("org.jetbrains.kotlin.plugin.serialization") version "1.9.0"
+    id("org.jetbrains.kotlin.plugin.serialization") version "1.9.20"
     id("com.google.android.libraries.mapsplatform.secrets-gradle-plugin")
     id("kotlin-parcelize")
 }

app/src/main/kotlin/com/google/ai/sample/feature/multimodal/PhotoReasoningViewModel.kt

@@ -90,15 +90,7 @@ class PhotoReasoningViewModel(
     ) {
         _uiState.value = PhotoReasoningUiState.Loading
 
-        // Get the system message
-        val systemMessageText = _systemMessage.value
-
-        // Create the prompt with system message if available
-        val prompt = if (systemMessageText.isNotBlank()) {
-            "System Message: $systemMessageText\n\nFOLLOW THE INSTRUCTIONS STRICTLY: $userInput"
-        } else {
-            "FOLLOW THE INSTRUCTIONS STRICTLY: $userInput"
-        }
+        val prompt = "FOLLOW THE INSTRUCTIONS STRICTLY: $userInput"
 
         // Store the current user input and selected images
         currentUserInput = userInput
@@ -542,6 +534,10 @@ class PhotoReasoningViewModel(
     private fun rebuildChatHistory() {
         // Convert the current chat messages to Content objects for the chat history
         val history = mutableListOf<Content>()
+
+        if (_systemMessage.value.isNotBlank()) {
+            history.add(content(role = "user") { text(_systemMessage.value) })
+        }
 
         // Group messages by participant to create proper conversation turns
         var currentUserContent = ""
@@ -607,10 +603,13 @@ class PhotoReasoningViewModel(
         _chatState.clearMessages()
         _chatMessagesFlow.value = emptyList()
 
-        // Reset the chat with empty history
-        chat = generativeModel.startChat(
-            history = emptyList()
-        )
+        // Reset the chat with empty history or system message
+        val initialHistory = if (_systemMessage.value.isNotBlank()) {
+            listOf(content(role = "user") { text(_systemMessage.value) })
+        } else {
+            emptyList()
+        }
+        chat = generativeModel.startChat(history = initialHistory)
 
         // Also clear from SharedPreferences if context is provided
         context?.let {