Remove emitLastMessage from continue(), use prompt(AppMessage) instead

Cleans up the temporary emitLastMessage plumbing since we now use
Agent.prompt(AppMessage) for hook messages instead of appendMessage+continue.

- Remove emitLastMessage parameter from Agent.continue()
- Remove from transport interface and implementations
- Remove from agentLoopContinue()

packages/agent/src/agent.ts

@@ -216,12 +216,7 @@ export class Agent {
 	 * Continue from the current context without adding a new user message.
 	 * Used for retry after overflow recovery when context already has user message or tool results.
 	 */
-	/**
-	 * Continue from the current context without adding a new user message.
-	 * Used for retry after overflow recovery when context already has user message or tool results.
-	 * @param emitLastMessage If true, emit message_start/message_end for the last message
-	 */
-	async continue(emitLastMessage?: boolean) {
+	async continue() {
 		const messages = this._state.messages;
 		if (messages.length === 0) {
 			throw new Error("No messages to continue from");
@@ -232,7 +227,7 @@ export class Agent {
 			throw new Error(`Cannot continue from message role: ${lastMessage.role}`);
 		}
 
-		await this._runAgentLoopContinue(emitLastMessage);
+		await this._runAgentLoopContinue();
 	}
 
 	/**
@@ -249,10 +244,10 @@ export class Agent {
 	/**
 	 * Internal: Continue the agent loop from current context.
 	 */
-	private async _runAgentLoopContinue(emitLastMessage?: boolean) {
+	private async _runAgentLoopContinue() {
 		const { llmMessages, cfg } = await this._prepareRun();
 
-		const events = this.transport.continue(llmMessages, cfg, this.abortController!.signal, emitLastMessage);
+		const events = this.transport.continue(llmMessages, cfg, this.abortController!.signal);
 
 		await this._processEvents(events);
 	}

packages/agent/src/transports/AppTransport.ts

@@ -380,7 +380,7 @@ export class AppTransport implements AgentTransport {
 		}
 	}
 
-	async *continue(messages: Message[], cfg: AgentRunConfig, signal?: AbortSignal, emitLastMessage?: boolean) {
+	async *continue(messages: Message[], cfg: AgentRunConfig, signal?: AbortSignal) {
 		const authToken = await this.options.getAuthToken();
 		if (!authToken) {
 			throw new Error("Auth token is required for AppTransport");
@@ -390,7 +390,7 @@ export class AppTransport implements AgentTransport {
 		const context = this.buildContext(messages, cfg);
 		const pc = this.buildLoopConfig(cfg);
 
-		for await (const ev of agentLoopContinue(context, pc, signal, streamFn as any, emitLastMessage)) {
+		for await (const ev of agentLoopContinue(context, pc, signal, streamFn as any)) {
 			yield ev;
 		}
 	}

packages/agent/src/transports/ProviderTransport.ts

@@ -73,12 +73,12 @@ export class ProviderTransport implements AgentTransport {
 		}
 	}
 
-	async *continue(messages: Message[], cfg: AgentRunConfig, signal?: AbortSignal, emitLastMessage?: boolean) {
+	async *continue(messages: Message[], cfg: AgentRunConfig, signal?: AbortSignal) {
 		const model = this.getModel(cfg);
 		const context = this.buildContext(messages, cfg);
 		const pc = this.buildLoopConfig(model, cfg);
 
-		for await (const ev of agentLoopContinue(context, pc, signal, undefined, emitLastMessage)) {
+		for await (const ev of agentLoopContinue(context, pc, signal)) {
 			yield ev;
 		}
 	}

packages/agent/src/transports/types.ts

@@ -28,10 +28,5 @@ export interface AgentTransport {
 	): AsyncIterable<AgentEvent>;
 
 	/** Continue from current context (no new user message) */
-	continue(
-		messages: Message[],
-		config: AgentRunConfig,
-		signal?: AbortSignal,
-		emitLastMessage?: boolean,
-	): AsyncIterable<AgentEvent>;
+	continue(messages: Message[], config: AgentRunConfig, signal?: AbortSignal): AsyncIterable<AgentEvent>;
 }

packages/ai/src/agent/agent-loop.ts

@@ -44,14 +44,12 @@ export function agentLoop(
  * Continue an agent loop from the current context without adding a new message.
  * Used for retry after overflow - context already has user message or tool results.
  * Throws if the last message is not a user message or tool result.
- * @param emitLastMessage If true, emit message_start/message_end for the last message in context
  */
 export function agentLoopContinue(
 	context: AgentContext,
 	config: AgentLoopConfig,
 	signal?: AbortSignal,
 	streamFn?: typeof streamSimple,
-	emitLastMessage?: boolean,
 ): EventStream<AgentEvent, AgentContext["messages"]> {
 	// Validate that we can continue from this context
 	const lastMessage = context.messages[context.messages.length - 1];
@@ -70,12 +68,7 @@ export function agentLoopContinue(
 
 		stream.push({ type: "agent_start" });
 		stream.push({ type: "turn_start" });
-
-		// Optionally emit events for the last message (used when message was added outside the loop)
-		if (emitLastMessage) {
-			stream.push({ type: "message_start", message: lastMessage });
-			stream.push({ type: "message_end", message: lastMessage });
-		}
+		// No user message events - we're continuing from existing context
 
 		await runLoop(currentContext, newMessages, config, signal, stream, streamFn);
 	})();