Add extraContext to Conversation sendMessage methods.

docs/api/kotlin/getting_started.md

@@ -166,15 +166,15 @@ engine.createConversation(conversationConfig).use { conversation ->
 
 There are three ways to send messages:
 
--   **`sendMessage(contents): Message`**: Synchronous call that blocks until the
-    model returns a complete response. This is simpler for basic
-    request/response interactions.
--   **`sendMessageAsync(contents, callback)`**: Asynchronous call for streaming
-    responses. This is better for long-running requests or when you want to
-    display the response as it's being generated.
--   **`sendMessageAsync(contents): Flow<Message>`**: Asynchronous call that
-    returns a Kotlin Flow for streaming responses. This is the recommended
-    approach for Coroutine users.
+-   **`sendMessage(contents, extraContext): Message`**: Synchronous call that
+    blocks until the model returns a complete response. This is simpler for
+    basic request/response interactions.
+-   **`sendMessageAsync(contents, callback, extraContext)`**: Asynchronous call
+    for streaming responses. This is better for long-running requests or when
+    you want to display the response as it's being generated.
+-   **`sendMessageAsync(contents, extraContext): Flow<Message>`**: Asynchronous
+    call that returns a Kotlin Flow for streaming responses. This is the
+    recommended approach for Coroutine users.
 
 **Synchronous Example:**
 
@@ -456,6 +456,33 @@ To try out tool use, clone the repo and run with
 bazel run -c opt //kotlin/java/com/google/ai/edge/litertlm/example:tool -- <abs_model_path>
 ```
 
+### 7. Extra Template Context Variables
+
+You can pass extra context variables to the prompt template for rendering.
+This allows you to customize the model's behavior based on dynamic values.
+
+`extraContext` is an optional `Map<String, Any>` that can be passed to
+`sendMessage` and `sendMessageAsync`. These variables are merged with the extra
+context provided in the `Preface` (if any), with keys in the message-level
+context overwriting those in the `Preface`.
+
+```kotlin
+val extraContext = mapOf(
+    "user_name" to "Alice",
+    "enable_thinking" to true
+)
+
+// Synchronous
+val response = conversation.sendMessage("Hello!", extraContext = extraContext)
+
+// Asynchronous with Flow
+conversation.sendMessageAsync("Hello!", extraContext = extraContext)
+    .collect { ... }
+```
+
+These variables are used within the Jinja-style prompt templates, e.g.,
+`{{ user_name }}` or `{% if enable_thinking %}`.
+
 ## Error Handling
 
 API methods can throw `LiteRtLmJniException` for errors from the native layer or

kotlin/java/com/google/ai/edge/litertlm/Conversation.kt

@@ -86,18 +86,21 @@ class Conversation(
    * [RECURRING_TOOL_CALL_LIMIT] times.
    *
    * @param message The message to send to the model.
+   * @param extraContext Optional context used for prompt template rendering.
    * @return The model's response message.
    * @throws IllegalStateException if the conversation is not alive, if the native layer returns an
    *   invalid response, or if the tool call limit is exceeded.
    * @throws LiteRtLmJniException if an error occurs during the native call.
    */
-  fun sendMessage(message: Message): Message {
+  fun sendMessage(message: Message, extraContext: Map<String, Any> = emptyMap()): Message {
     checkIsAlive()
 
     var currentMessageJson = message.toJson()
+    var extraContextJsonString = extraContext.toJsonObject().toString()
 
     for (i in 0..<RECURRING_TOOL_CALL_LIMIT) {
-      val responseJsonString = LiteRtLmJni.nativeSendMessage(handle, currentMessageJson.toString())
+      val responseJsonString =
+        LiteRtLmJni.nativeSendMessage(handle, currentMessageJson.toString(), extraContextJsonString)
       val responseJsonObject = JsonParser.parseString(responseJsonString).asJsonObject
 
       if (responseJsonObject.has("tool_calls")) {
@@ -124,13 +127,14 @@ class Conversation(
    * [RECURRING_TOOL_CALL_LIMIT] times.
    *
    * @param contents The list of contents to send to the model.
+   * @param extraContext Optional context used for prompt template rendering.
    * @return The model's response message.
    * @throws IllegalStateException if the conversation is not alive, if the native layer returns an
    *   invalid response, or if the tool call limit is exceeded.
    * @throws LiteRtLmJniException if an error occurs during the native call.
    */
-  fun sendMessage(contents: Contents): Message {
-    return sendMessage(Message.user(contents))
+  fun sendMessage(contents: Contents, extraContext: Map<String, Any> = emptyMap()): Message {
+    return sendMessage(Message.user(contents), extraContext)
   }
 
   /**
@@ -142,12 +146,14 @@ class Conversation(
    * [RECURRING_TOOL_CALL_LIMIT] times.
    *
    * @param text The text to send to the model.
+   * @param extraContext Optional context used for prompt template rendering.
    * @return The model's response message.
    * @throws IllegalStateException if the conversation is not alive, if the native layer returns an
    *   invalid response, or if the tool call limit is exceeded.
    * @throws LiteRtLmJniException if an error occurs during the native call.
    */
-  fun sendMessage(text: String): Message = sendMessage(Contents.of(text))
+  fun sendMessage(text: String, extraContext: Map<String, Any> = emptyMap()): Message =
+    sendMessage(Contents.of(text), extraContext)
 
   /**
    * Send a message to the model and returns the response async with a callback.
@@ -159,14 +165,26 @@ class Conversation(
    *
    * @param message The message to send to the model.
    * @param callback The callback to receive the streaming responses.
+   * @param extraContext Optional context used for prompt template rendering.
    * @throws IllegalStateException if the conversation has already been closed or the content is
    *   empty.
    */
-  fun sendMessageAsync(message: Message, callback: MessageCallback) {
+  fun sendMessageAsync(
+    message: Message,
+    callback: MessageCallback,
+    extraContext: Map<String, Any> = emptyMap(),
+  ) {
     checkIsAlive()
 
+    val extraContextJsonString = extraContext.toJsonObject().toString()
+
     val jniCallback = JniMessageCallbackImpl(callback)
-    LiteRtLmJni.nativeSendMessageAsync(handle, message.toJson().toString(), jniCallback)
+    LiteRtLmJni.nativeSendMessageAsync(
+      handle,
+      message.toJson().toString(),
+      extraContextJsonString,
+      jniCallback,
+    )
   }
 
   /**
@@ -179,11 +197,15 @@ class Conversation(
    *
    * @param contents The list of contents to send to the model.
    * @param callback The callback to receive the streaming responses.
+   * @param extraContext Optional context used for prompt template rendering.
    * @throws IllegalStateException if the conversation has already been closed or the content is
    *   empty.
    */
-  fun sendMessageAsync(contents: Contents, callback: MessageCallback) =
-    sendMessageAsync(Message.user(contents), callback)
+  fun sendMessageAsync(
+    contents: Contents,
+    callback: MessageCallback,
+    extraContext: Map<String, Any> = emptyMap(),
+  ) = sendMessageAsync(Message.user(contents), callback, extraContext)
 
   /**
    * Send a text to the model and returns the response async with a callback.
@@ -195,11 +217,15 @@ class Conversation(
    *
    * @param text The text to send to the model.
    * @param callback The callback to receive the streaming responses.
+   * @param extraContext Optional context used for prompt template rendering.
    * @throws IllegalStateException if the conversation has already been closed or the content is
    *   empty.
    */
-  fun sendMessageAsync(text: String, callback: MessageCallback) =
-    sendMessageAsync(Contents.of(text), callback)
+  fun sendMessageAsync(
+    text: String,
+    callback: MessageCallback,
+    extraContext: Map<String, Any> = emptyMap(),
+  ) = sendMessageAsync(Contents.of(text), callback, extraContext)
 
   /**
    * Sends a message to the model and returns the response async as a [Flow].
@@ -210,11 +236,15 @@ class Conversation(
    * [RECURRING_TOOL_CALL_LIMIT] times.
    *
    * @param message The message to send to the model.
+   * @param extraContext Optional context used for prompt template rendering.
    * @return A Flow of messages representing the model's response.
    * @throws IllegalStateException if the conversation has already been closed or the content is
    *   empty.
    */
-  fun sendMessageAsync(message: Message): Flow<Message> = callbackFlow {
+  fun sendMessageAsync(
+    message: Message,
+    extraContext: Map<String, Any> = emptyMap(),
+  ): Flow<Message> = callbackFlow {
     sendMessageAsync(
       message,
       object : MessageCallback {
@@ -230,6 +260,7 @@ class Conversation(
           close(throwable)
         }
       },
+      extraContext,
     )
     awaitClose {}
   }
@@ -243,11 +274,15 @@ class Conversation(
    * [RECURRING_TOOL_CALL_LIMIT] times.
    *
    * @param contents The list of contents to send to the model.
+   * @param extraContext Optional context used for prompt template rendering.
    * @return A Flow of messages representing the model's response.
    * @throws IllegalStateException if the conversation has already been closed or the content is
    *   empty.
    */
-  fun sendMessageAsync(contents: Contents): Flow<Message> = sendMessageAsync(Message.user(contents))
+  fun sendMessageAsync(
+    contents: Contents,
+    extraContext: Map<String, Any> = emptyMap(),
+  ): Flow<Message> = sendMessageAsync(Message.user(contents), extraContext)
 
   /**
    * Sends a text to the model and returns the response async as a [Flow].
@@ -258,11 +293,13 @@ class Conversation(
    * [RECURRING_TOOL_CALL_LIMIT] times.
    *
    * @param text The text to send to the model.
+   * @param extraContext Optional context used for prompt template rendering.
    * @return A Flow of messages representing the model's response.
    * @throws IllegalStateException if the conversation has already been closed or the content is
    *   empty.
    */
-  fun sendMessageAsync(text: String): Flow<Message> = sendMessageAsync(Contents.of(text))
+  fun sendMessageAsync(text: String, extraContext: Map<String, Any> = emptyMap()): Flow<Message> =
+    sendMessageAsync(Contents.of(text), extraContext)
 
   private fun handleToolCalls(toolCallsJsonObject: JsonObject): JsonObject {
     val toolCallsJSONArray = toolCallsJsonObject.getAsJsonArray("tool_calls")
@@ -328,6 +365,7 @@ class Conversation(
         LiteRtLmJni.nativeSendMessageAsync(
           handle,
           localToolResponse.toString(),
+          "{}",
           this@JniMessageCallbackImpl,
         )
         pendingToolResponseJSONMessage = null // Clear after sending

kotlin/java/com/google/ai/edge/litertlm/LiteRtLmJni.kt

@@ -215,6 +215,7 @@ internal object LiteRtLmJni {
   external fun nativeSendMessageAsync(
     conversationPointer: Long,
     messageJsonString: String,
+    extraContextJsonString: String,
     callback: JniMessageCallback,
   )
 
@@ -225,7 +226,11 @@ internal object LiteRtLmJni {
    * @param messageJsonString The message to be processed by the native conversation instance.
    * @return The response message in JSON string format.
    */
-  external fun nativeSendMessage(conversationPointer: Long, messageJsonString: String): String
+  external fun nativeSendMessage(
+    conversationPointer: Long,
+    messageJsonString: String,
+    extraContextJsonString: String,
+  ): String
 
   /**
    * Cancels the ongoing conversation process.

kotlin/java/com/google/ai/edge/litertlm/jni/BUILD

@@ -25,6 +25,7 @@ cc_binary(
     linkshared = 1,
     deps = [
         "@com_google_absl//absl/base:log_severity",
+        "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/functional:any_invocable",
         "@com_google_absl//absl/log:absl_log",
         "@com_google_absl//absl/log:globals",

kotlin/java/com/google/ai/edge/litertlm/jni/litertlm.cc

@@ -295,6 +295,19 @@ SamplerParameters CreateSamplerParamsFromJni(JNIEnv* env,
 
   return sampler_params;
 }
+
+nlohmann::ordered_json GetExtraContextJson(JNIEnv* env,
+                                           jstring extra_context_json_string) {
+  const char* extra_context_chars =
+      env->GetStringUTFChars(extra_context_json_string, nullptr);
+  nlohmann::ordered_json extra_context_json;
+  if (extra_context_chars != nullptr) {
+    extra_context_json = nlohmann::ordered_json::parse(extra_context_chars);
+  }
+  env->ReleaseStringUTFChars(extra_context_json_string, extra_context_chars);
+  return extra_context_json;
+}
+
 }  // namespace
 
 extern "C" {
@@ -851,7 +864,8 @@ LITERTLM_JNIEXPORT void JNICALL JNI_METHOD(nativeDeleteConversation)(
 
 LITERTLM_JNIEXPORT void JNICALL JNI_METHOD(nativeSendMessageAsync)(
     JNIEnv* env, jclass thiz, jlong conversation_pointer,
-    jstring messageJSONString, jobject callback) {
+    jstring messageJSONString, jstring extraContextJsonString,
+    jobject callback) {
   JavaVM* jvm = nullptr;
   if (env->GetJavaVM(&jvm) != JNI_OK) {
     ThrowLiteRtLmJniException(env, "Failed to get JavaVM");
@@ -866,6 +880,13 @@ LITERTLM_JNIEXPORT void JNICALL JNI_METHOD(nativeSendMessageAsync)(
       nlohmann::ordered_json::parse(json_chars);
   env->ReleaseStringUTFChars(messageJSONString, json_chars);
 
+  litert::lm::OptionalArgs optional_args;
+  nlohmann::ordered_json extra_context =
+      GetExtraContextJson(env, extraContextJsonString);
+  if (!extra_context.is_null() && !extra_context.empty()) {
+    optional_args.extra_context = extra_context;
+  }
+
   jobject callback_global = env->NewGlobalRef(callback);
   jclass callback_class = env->GetObjectClass(callback_global);
   jmethodID on_message_mid =
@@ -932,8 +953,8 @@ LITERTLM_JNIEXPORT void JNICALL JNI_METHOD(nativeSendMessageAsync)(
         }
       };
 
-  auto status =
-      conversation->SendMessageAsync(json_message, std::move(callback_fn));
+  auto status = conversation->SendMessageAsync(
+      json_message, std::move(callback_fn), std::move(optional_args));
 
   if (!status.ok()) {
     ThrowLiteRtLmJniException(
@@ -943,7 +964,7 @@ LITERTLM_JNIEXPORT void JNICALL JNI_METHOD(nativeSendMessageAsync)(
 
 LITERTLM_JNIEXPORT jstring JNICALL JNI_METHOD(nativeSendMessage)(
     JNIEnv* env, jclass thiz, jlong conversation_pointer,
-    jstring messageJSONString) {
+    jstring messageJSONString, jstring extraContextJsonString) {
   Conversation* conversation =
       reinterpret_cast<Conversation*>(conversation_pointer);
 
@@ -952,7 +973,15 @@ LITERTLM_JNIEXPORT jstring JNICALL JNI_METHOD(nativeSendMessage)(
       nlohmann::ordered_json::parse(json_chars);
   env->ReleaseStringUTFChars(messageJSONString, json_chars);
 
-  auto response = conversation->SendMessage(json_message);
+  litert::lm::OptionalArgs optional_args;
+  nlohmann::ordered_json extra_context =
+      GetExtraContextJson(env, extraContextJsonString);
+  if (!extra_context.is_null() && !extra_context.empty()) {
+    optional_args.extra_context = extra_context;
+  }
+
+  auto response =
+      conversation->SendMessage(json_message, std::move(optional_args));
   if (!response.ok()) {
     ThrowLiteRtLmJniException(env, "Failed to call nativeSendMessage: " +
                                        response.status().ToString());

runtime/conversation/BUILD

@@ -106,7 +106,6 @@ cc_library(
         "@com_google_absl//absl/time",
         "@nlohmann_json//:json",
         "//runtime/components:prompt_template",
-        "//runtime/components:tokenizer",
         "//runtime/components/constrained_decoding:constraint",
         "//runtime/components/constrained_decoding:constraint_provider",
         "//runtime/components/constrained_decoding:constraint_provider_config",
@@ -137,6 +136,7 @@ cc_test(
         ":conversation",
         ":io_types",
         "@com_google_googletest//:gtest_main",
+        "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/functional:any_invocable",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",