diff --git a/packages/ai/src/api/openai-codex-responses.ts b/packages/ai/src/api/openai-codex-responses.ts
index 52e1becfb..e72ec06aa 100644
--- a/packages/ai/src/api/openai-codex-responses.ts
+++ b/packages/ai/src/api/openai-codex-responses.ts
@@ -662,7 +662,7 @@ async function processStream(
 	grammarToolInputProperties: ReadonlyMap<string, string>,
 	options?: OpenAICodexResponsesOptions,
 ): Promise<void> {
-	await processResponsesStream(mapCodexEvents(parseSSE(response, options?.signal)), output, stream, model, {
+	await processResponsesStream(mapCodexEvents(parseSSE(response, options?.signal), output), output, stream, model, {
 		serviceTier: options?.serviceTier,
 		grammarToolInputProperties,
 		resolveServiceTier: resolveCodexServiceTier,
@@ -719,7 +719,10 @@ function extractCodexEventError(event: Record<string, unknown>): { code?: string
 	};
 }
 
-async function* mapCodexEvents(events: AsyncIterable<Record<string, unknown>>): AsyncGenerator<ResponseStreamEvent> {
+async function* mapCodexEvents(
+	events: AsyncIterable<Record<string, unknown>>,
+	output: AssistantMessage,
+): AsyncGenerator<ResponseStreamEvent> {
 	for await (const event of events) {
 		const type = typeof event.type === "string" ? event.type : undefined;
 		if (!type) continue;
@@ -740,7 +743,10 @@ async function* mapCodexEvents(events: AsyncIterable<Record<string, unknown>>):
 		}
 
 		if (type === "response.done" || type === "response.completed" || type === "response.incomplete") {
-			const response = (event as { response?: { status?: unknown } }).response;
+			const response = (event as { response?: { status?: unknown; end_turn?: unknown } }).response;
+			if (typeof response?.end_turn === "boolean") {
+				output.endTurn = response.end_turn;
+			}
 			const normalizedResponse = response
 				? { ...response, status: normalizeCodexStatus(response.status) }
 				: response;
@@ -1504,7 +1510,7 @@ async function processWebSocketStream(
 		socket.send(JSON.stringify({ type: "response.create", ...requestBody }));
 		await processResponsesStream(
 			startWebSocketOutputOnFirstEvent(
-				mapCodexEvents(parseWebSocket(socket, options?.signal, idleTimeoutMs)),
+				mapCodexEvents(parseWebSocket(socket, options?.signal, idleTimeoutMs), output),
 				onStart,
 			),
 			output,
diff --git a/packages/ai/src/types.ts b/packages/ai/src/types.ts
index 75e1d6f3c..5bf6c9fa6 100644
--- a/packages/ai/src/types.ts
+++ b/packages/ai/src/types.ts
@@ -424,6 +424,11 @@ export interface AssistantMessage {
 	deferred?: DeferredHandle;
 	errorMessage?: string;
 	rawStopReason?: string;
+	/**
+	 * Provider indication of whether the model explicitly ended its turn.
+	 * Preserved for debugging and does not currently affect agent control flow.
+	 */
+	endTurn?: boolean;
 	timestamp: number; // Unix timestamp in milliseconds
 }
 
diff --git a/packages/ai/test/openai-codex-stream.test.ts b/packages/ai/test/openai-codex-stream.test.ts
index a8423c887..ccd7f51c6 100644
--- a/packages/ai/test/openai-codex-stream.test.ts
+++ b/packages/ai/test/openai-codex-stream.test.ts
@@ -49,9 +49,11 @@ function decodeCodexRequestBody(body: RequestInit["body"] | undefined): Record<s
 function buildSSEPayload({
 	status,
 	includeDone = false,
+	endTurn,
 }: {
 	status: "completed" | "incomplete";
 	includeDone?: boolean;
+	endTurn?: boolean;
 }): string {
 	const terminalType = status === "incomplete" ? "response.incomplete" : "response.completed";
 	const events = [
@@ -75,6 +77,7 @@ function buildSSEPayload({
 			type: terminalType,
 			response: {
 				status,
+				end_turn: endTurn,
 				incomplete_details: status === "incomplete" ? { reason: "max_output_tokens" } : null,
 				usage: {
 					input_tokens: 5,
@@ -210,7 +213,7 @@ describe("openai-codex streaming", () => {
 		process.env.PI_CODING_AGENT_DIR = tempDir;
 		const token = mockToken();
 		const encoder = new TextEncoder();
-		const sse = buildSSEPayload({ status: "completed", includeDone: true });
+		const sse = buildSSEPayload({ status: "completed", includeDone: true, endTurn: false });
 
 		const stream = new ReadableStream<Uint8Array>({
 			start(controller) {
@@ -263,6 +266,7 @@ describe("openai-codex streaming", () => {
 
 		expect(result.content.find((c) => c.type === "text")?.text).toBe("Hello");
 		expect(result.stopReason).toBe("stop");
+		expect(result.endTurn).toBe(false);
 	});
 
 	it("maps response.incomplete to stopReason length even when the SSE body stays open", async () => {
@@ -1273,6 +1277,7 @@ describe("openai-codex streaming", () => {
 						type: "response.completed",
 						response: {
 							status: "completed",
+							end_turn: false,
 							usage: {
 								input_tokens: 5,
 								output_tokens: 3,
@@ -1317,12 +1322,13 @@ describe("openai-codex streaming", () => {
 			messages: [{ role: "user", content: "Say hello", timestamp: 1 }],
 		};
 
-		await streamSimpleOpenAICodexResponses(model, context, {
+		const result = await streamSimpleOpenAICodexResponses(model, context, {
 			apiKey: token,
 			sessionId: "session-auto",
 			transport: "auto",
 		}).result();
 
+		expect(result.endTurn).toBe(false);
 		expect(sentBodies).toHaveLength(1);
 		expect(capturedWebSocketHeaders?.["session-id"]).toBe("session-auto");
 		expect(capturedWebSocketHeaders?.session_id).toBeUndefined();
diff --git a/packages/server/src/protocol.ts b/packages/server/src/protocol.ts
index 99b5a948e..6180cf407 100644
--- a/packages/server/src/protocol.ts
+++ b/packages/server/src/protocol.ts
@@ -94,6 +94,7 @@ type _AiAssistantMessageFieldsAccountedFor = Assert<
 		| "deferred"
 		| "errorMessage"
 		| "rawStopReason"
+		| "endTurn"
 		| "timestamp"
 	>
 >;