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Fix Gemma image prefill prompt logic and UI #181

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Merged
kirklandsign merged 5 commits into from
Jan 27, 2026
Merged

Fix Gemma image prefill prompt logic and UI #181

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2da8ab4
[Android] Fix Gemma image prefill prompt logic
kirklandsign Jan 27, 2026
4af3429
Fix prompt format
kirklandsign Jan 27, 2026
2c6ebd5
UI
kirklandsign Jan 27, 2026
c4ae6c8
Try again
kirklandsign Jan 27, 2026
2fe4f7e
More fixes
kirklandsign Jan 27, 2026
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16 changes: 13 additions & 3 deletions llm/android/LlamaDemo/app/src/main/java/com/example/executorchllamademo/PromptFormat.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -85,12 +85,22 @@ object PromptFormat {
@JvmStatic
fun getLlavaPresetPrompt(): String {
return "A chat between a curious human and an artificial intelligence assistant. The assistant" +
" gives helpful, detailed, and polite answers to the human's questions. USER: "
" gives helpful, detailed, and polite answers to the human's questions."
}

@JvmStatic
fun getLlavaFirstTurnUserPrompt(): String {
return "$USER_PLACEHOLDER ASSISTANT:"
fun getLlavaMultimodalUserPrompt(): String {
return "USER: $USER_PLACEHOLDER ASSISTANT:"
}

@JvmStatic
fun getGemmaPreImagePrompt(): String {
return "<start_of_turn>user\n<start_of_image>"
}

@JvmStatic
fun getGemmaMultimodalUserPrompt(): String {
return "$USER_PLACEHOLDER<end_of_turn>\n<start_of_turn>model"
}

@JvmStatic
Expand Down
29 changes: 18 additions & 11 deletions ...LlamaDemo/app/src/main/java/com/example/executorchllamademo/ui/viewmodel/ChatViewModel.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -110,23 +110,26 @@ class ChatViewModel(application: Application) : AndroidViewModel(application), L
val isLoadModel = updatedSettingsFields.isLoadModel
if (isUpdated) {
checkForClearChatHistory(updatedSettingsFields)
// Update media capabilities after settings are updated
setBackendMode(updatedSettingsFields.backendType)

if (isLoadModel) {
// Update local copy BEFORE checking media capabilities
val settingsWithLoadFlagCleared = updatedSettingsFields.copy(isLoadModel = false)
currentSettingsFields = settingsWithLoadFlagCleared
demoSharedPreferences.saveModuleSettings(settingsWithLoadFlagCleared)

// Update media capabilities after settings are updated
setBackendMode(updatedSettingsFields.backendType)

loadLocalModelAndParameters(
updatedSettingsFields.modelFilePath,
updatedSettingsFields.tokenizerFilePath,
updatedSettingsFields.dataPath,
updatedSettingsFields.temperature.toFloat()
)
// Save with isLoadModel = false and update local copy to match,
// preventing duplicate "To get started..." messages on subsequent calls
val settingsWithLoadFlagCleared = updatedSettingsFields.copy(isLoadModel = false)
demoSharedPreferences.saveModuleSettings(settingsWithLoadFlagCleared)
currentSettingsFields = settingsWithLoadFlagCleared
} else {
currentSettingsFields = updatedSettingsFields.copy()
// Update media capabilities after settings are updated
setBackendMode(updatedSettingsFields.backendType)
if (module == null) {
addSystemMessage(systemPromptMessage)
}
Expand Down Expand Up @@ -317,13 +320,13 @@ class ChatViewModel(application: Application) : AndroidViewModel(application), L
val processedImageList = getProcessedImagesForModel(_selectedImages)
if (processedImageList.isNotEmpty()) {
_messages.add(
Message("Llava - Starting image Prefill.", false, MessageType.SYSTEM, 0)
Message("Starting image prefill.", false, MessageType.SYSTEM, 0)
)
executor.execute {
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_MORE_FAVORABLE)
ETLogging.getInstance().log("Starting runnable prefill image")
val img = processedImageList[0]
ETLogging.getInstance().log("Llava start prefill image")
ETLogging.getInstance().log("Starting prefill image")
if (currentSettingsFields.modelType == ModelType.LLAVA_1_5) {
module?.prefillImages(
img.getInts(),
Expand All @@ -332,6 +335,7 @@ class ChatViewModel(application: Application) : AndroidViewModel(application), L
ModelUtils.VISION_MODEL_IMAGE_CHANNELS
)
} else if (currentSettingsFields.modelType == ModelType.GEMMA_3) {
module?.prefillPrompt(PromptFormat.getGemmaPreImagePrompt())
module?.prefillImages(
img.getFloats(),
img.width,
Expand Down Expand Up @@ -372,8 +376,11 @@ class ChatViewModel(application: Application) : AndroidViewModel(application), L
val rawPrompt = inputText
val finalPrompt: String

if (currentSettingsFields.modelType == ModelType.LLAVA_1_5 && shouldAddSystemPrompt) {
finalPrompt = PromptFormat.getLlavaFirstTurnUserPrompt()
if (currentSettingsFields.modelType == ModelType.LLAVA_1_5 && _selectedImages.isNotEmpty()) {
finalPrompt = PromptFormat.getLlavaMultimodalUserPrompt()
.replace(PromptFormat.USER_PLACEHOLDER, rawPrompt)
} else if (currentSettingsFields.modelType == ModelType.GEMMA_3 && _selectedImages.isNotEmpty()) {
finalPrompt = PromptFormat.getGemmaMultimodalUserPrompt()
.replace(PromptFormat.USER_PLACEHOLDER, rawPrompt)
} else {
finalPrompt = (if (shouldAddSystemPrompt) currentSettingsFields.getFormattedSystemPrompt() else "") +
Expand Down