diff --git a/src/app-server/client.ts b/src/app-server/client.ts
index 8cde630c..21e4362c 100644
--- a/src/app-server/client.ts
+++ b/src/app-server/client.ts
@@ -372,11 +372,17 @@ export class AppServerClient {
     return this.request("turn/start", params);
   }
 
-  steerTurn(threadId: string, expectedTurnId: string, input: string | UserInput[]): Promise<TurnSteerResponse> {
+  steerTurn(
+    threadId: string,
+    expectedTurnId: string,
+    input: string | UserInput[],
+    clientUserMessageId?: string | null,
+  ): Promise<TurnSteerResponse> {
     return this.request("turn/steer", {
       threadId,
       expectedTurnId,
       input: toUserInput(input),
+      ...(clientUserMessageId !== undefined ? { clientUserMessageId } : {}),
     });
   }
 
diff --git a/src/features/chat/controllers/submission/turn-submission-controller.ts b/src/features/chat/controllers/submission/turn-submission-controller.ts
index 805de42f..8ea0b538 100644
--- a/src/features/chat/controllers/submission/turn-submission-controller.ts
+++ b/src/features/chat/controllers/submission/turn-submission-controller.ts
@@ -112,13 +112,14 @@ export class TurnSubmissionController {
     }
 
     const codexInput = codexInputOverride ?? this.host.codexInput(text);
+    const localSteerId = `local-steer-${String(Date.now())}`;
     this.host.setDraft("", { clearSuggestions: true });
 
     try {
-      await client.steerTurn(threadId, expectedTurnId, codexInput);
+      await client.steerTurn(threadId, expectedTurnId, codexInput, localSteerId);
       this.host.state.addLocalUserMessage(
         localUserMessageItemFromInput({
-          id: `local-steer-${String(Date.now())}`,
+          id: localSteerId,
           text,
           turnId: expectedTurnId,
           referencedThread,
diff --git a/tests/app-server/app-server-client.test.ts b/tests/app-server/app-server-client.test.ts
index a395227b..9073b028 100644
--- a/tests/app-server/app-server-client.test.ts
+++ b/tests/app-server/app-server-client.test.ts
@@ -199,13 +199,14 @@ describe("AppServerClient", () => {
     getTransport().emitLine({ id: 1, result: { codexHome: "/tmp/codex" } satisfies Partial<InitializeResponse> });
     await connecting;
 
-    const steering = client.steerTurn("thread-1", "turn-1", "Please adjust course.");
+    const steering = client.steerTurn("thread-1", "turn-1", "Please adjust course.", "local-steer-1");
     expect(getTransport().sent[2]).toMatchObject({
       id: 2,
       method: "turn/steer",
       params: {
         threadId: "thread-1",
         expectedTurnId: "turn-1",
+        clientUserMessageId: "local-steer-1",
         input: [{ type: "text", text: "Please adjust course.", text_elements: [] }],
       },
     });
diff --git a/tests/features/chat/controllers/submission/turn-submission-controller.test.ts b/tests/features/chat/controllers/submission/turn-submission-controller.test.ts
index 924a977e..e09e895f 100644
--- a/tests/features/chat/controllers/submission/turn-submission-controller.test.ts
+++ b/tests/features/chat/controllers/submission/turn-submission-controller.test.ts
@@ -113,9 +113,12 @@ describe("TurnSubmissionController", () => {
 
     await controller.sendTurnText("follow up");
 
-    expect(steerTurn).toHaveBeenCalledWith("thread", "turn", textInput("follow up"));
+    expect(steerTurn).toHaveBeenCalledWith("thread", "turn", textInput("follow up"), expect.stringMatching(/^local-steer-\d+$/));
     expect(startTurn).not.toHaveBeenCalled();
     expect(host.setStatus).toHaveBeenCalledWith("Steered current turn.");
-    expect(stateStore.getState().displayItems.some((item) => item.kind === "message" && item.text === "follow up")).toBe(true);
+    const localSteerId = steerTurn.mock.calls[0]?.[3];
+    expect(
+      stateStore.getState().displayItems.some((item) => item.kind === "message" && item.id === localSteerId && item.text === "follow up"),
+    ).toBe(true);
   });
 });