diff --git a/src/gateway/server-methods/chat.ts b/src/gateway/server-methods/chat.ts
index edbab03789ea..0a29ff653126 100644
--- a/src/gateway/server-methods/chat.ts
+++ b/src/gateway/server-methods/chat.ts
@@ -2943,6 +2943,7 @@ export const chatHandlers: GatewayRequestHandlers = {
     }
     const rawSessionKey = p.sessionKey;
     const agentIdOverride = normalizeOptionalText(p.agentId);
+    const clientRunId = p.idempotencyKey;
     const requestedAgentId = resolveRequestedChatAgentId({
       cfg: (context as { getRuntimeConfig?: () => OpenClawConfig }).getRuntimeConfig?.(),
       requestedSessionKey: rawSessionKey,
@@ -2959,6 +2960,7 @@ export const chatHandlers: GatewayRequestHandlers = {
       {
         phase: "agent-turn",
         attributes: {
+          runId: clientRunId,
           hasAttachments: normalizedAttachments.length > 0,
           hasExplicitOrigin: explicitOriginResult.value !== undefined,
         },
@@ -3013,7 +3015,6 @@ export const chatHandlers: GatewayRequestHandlers = {
       overrideMs: p.timeoutMs,
     });
     const now = Date.now();
-    const clientRunId = p.idempotencyKey;
 
     const sendPolicy = resolveSendPolicy({
       cfg,
@@ -3347,6 +3348,11 @@ export const chatHandlers: GatewayRequestHandlers = {
         channel: INTERNAL_MESSAGE_CHANNEL,
       });
       const chatSendTraceAttributes = {
+        runId: clientRunId,
+        sessionKey,
+        agentId: selectedAgent.agentId ?? agentId,
+        provider: resolvedSessionModel.provider,
+        model: resolvedSessionModel.model,
         hasAttachments: normalizedAttachments.length > 0,
         hasExplicitOrigin: explicitOriginResult.value !== undefined,
         hasConnectedClient: client?.connect !== undefined,
diff --git a/src/gateway/server.chat.gateway-server-chat-b.test.ts b/src/gateway/server.chat.gateway-server-chat-b.test.ts
index 1adebd209b6a..fe4678ad5140 100644
--- a/src/gateway/server.chat.gateway-server-chat-b.test.ts
+++ b/src/gateway/server.chat.gateway-server-chat-b.test.ts
@@ -116,6 +116,15 @@ async function writeMainSessionTranscript(sessionDir: string, lines: string[]) {
   await fs.writeFile(path.join(sessionDir, "sess-main.jsonl"), `${lines.join("\n")}\n`, "utf-8");
 }
 
+async function readTimelineEvents(filePath: string): Promise<Array<Record<string, unknown>>> {
+  const raw = await fs.readFile(filePath, "utf-8");
+  return raw
+    .trim()
+    .split("\n")
+    .filter(Boolean)
+    .map((line) => JSON.parse(line) as Record<string, unknown>);
+}
+
 async function fetchHistoryMessages(
   ws: GatewaySocket,
   params?: {
@@ -1178,6 +1187,60 @@ describe("gateway server chat", () => {
     });
   });
 
+  test("chat.send diagnostics timeline carries run correlation attributes", async () => {
+    const timelineDir = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-chat-timeline-"));
+    const timelinePath = path.join(timelineDir, "timeline.jsonl");
+    const previousDiagnostics = process.env.OPENCLAW_DIAGNOSTICS;
+    const previousTimelinePath = process.env.OPENCLAW_DIAGNOSTICS_TIMELINE_PATH;
+    process.env.OPENCLAW_DIAGNOSTICS = "timeline";
+    process.env.OPENCLAW_DIAGNOSTICS_TIMELINE_PATH = timelinePath;
+    try {
+      await withGatewayChatHarness(async ({ ws, createSessionDir }) => {
+        const spy = getReplyFromConfig;
+        await connectOk(ws);
+
+        await createSessionDir();
+        await writeMainSessionStore();
+        mockGetReplyFromConfigOnce(async () => undefined);
+
+        const sendRes = await rpcReq(ws, "chat.send", {
+          sessionKey: "main",
+          message: "hello",
+          idempotencyKey: "idem-timeline",
+        });
+        expect(sendRes.ok).toBe(true);
+
+        await vi.waitFor(() => {
+          expect(spy.mock.calls.length).toBeGreaterThan(0);
+        }, FAST_WAIT_OPTS);
+        await vi.waitFor(async () => {
+          const events = await readTimelineEvents(timelinePath);
+          expect(
+            events.some(
+              (event) =>
+                event.type === "span.end" &&
+                event.name === "gateway.chat_send.dispatch_inbound" &&
+                (event.attributes as Record<string, unknown> | undefined)?.runId ===
+                  "idem-timeline",
+            ),
+          ).toBe(true);
+        }, FAST_WAIT_OPTS);
+      });
+    } finally {
+      if (previousDiagnostics === undefined) {
+        delete process.env.OPENCLAW_DIAGNOSTICS;
+      } else {
+        process.env.OPENCLAW_DIAGNOSTICS = previousDiagnostics;
+      }
+      if (previousTimelinePath === undefined) {
+        delete process.env.OPENCLAW_DIAGNOSTICS_TIMELINE_PATH;
+      } else {
+        process.env.OPENCLAW_DIAGNOSTICS_TIMELINE_PATH = previousTimelinePath;
+      }
+      await fs.rm(timelineDir, { recursive: true, force: true, maxRetries: 5, retryDelay: 50 });
+    }
+  });
+
   test("chat.history hard-caps single oversized nested payloads", async () => {
     await withGatewayChatHarness(async ({ ws, createSessionDir }) => {
       const historyMaxBytes = 64 * 1024;
diff --git a/ui/src/ui/app-chat.ts b/ui/src/ui/app-chat.ts
index 7ed70a5858e4..2224435f4be0 100644
--- a/ui/src/ui/app-chat.ts
+++ b/ui/src/ui/app-chat.ts
@@ -27,13 +27,13 @@ import type { ChatSideResult } from "./chat/side-result.ts";
 import { executeSlashCommand } from "./chat/slash-command-executor.ts";
 import { parseSlashCommand, refreshSlashCommands } from "./chat/slash-commands.ts";
 import { formatConnectError } from "./connect-error.ts";
+import { resolveControlUiAuthHeader } from "./control-ui-auth.ts";
 import {
   controlUiNowMs,
   recordControlUiPerformanceEvent,
   roundedControlUiDurationMs,
   scheduleControlUiAfterPaint,
 } from "./control-ui-performance.ts";
-import { resolveControlUiAuthHeader } from "./control-ui-auth.ts";
 import {
   abortChatRun,
   appendUserChatMessage,
@@ -41,7 +41,9 @@ import {
   requestChatSend,
   sendDetachedChatMessage,
   sendSteerChatMessage,
+  type ChatEventPayload,
   type ChatHistoryResult,
+  type ChatSendAck,
   type ChatState,
 } from "./controllers/chat.ts";
 import { loadModels } from "./controllers/models.ts";
@@ -105,6 +107,7 @@ export type ChatHost = ChatInputHistoryState & {
   refreshSessionsAfterChat: Map<string, ChatSessionRefreshTarget>;
   pendingAbort?: { runId?: string | null; sessionKey: string; agentId?: string } | null;
   chatSubmitGuards?: Map<string, Promise<void>>;
+  chatSendTimingsByRun?: Map<string, ChatSendTimingEntry>;
   assistantAgentId?: string | null;
   agentsList?: { defaultId?: string | null; mainKey?: string | null } | null;
   eventLogBuffer?: unknown[];
@@ -395,8 +398,9 @@ function enqueuePendingSendMessage(
   attachments?: ChatAttachment[],
   refreshSessions?: boolean,
   submittedAtMs = controlUiNowMs(),
-  sendState: ChatQueueItem["sendState"] =
-    host.connected && host.client ? "sending" : "waiting-reconnect",
+  sendState: ChatQueueItem["sendState"] = host.connected && host.client
+    ? "sending"
+    : "waiting-reconnect",
 ): ChatQueueItem | null {
   const trimmed = text.trim();
   const hasAttachments = Boolean(attachments && attachments.length > 0);
@@ -541,9 +545,9 @@ function cancelPendingSendBeforeRequest(
     restoreComposer && opts.previousDraft != null && !host.chatMessage.trim();
   const willRestoreAttachments = Boolean(
     restoreComposer &&
-      opts.previousAttachments?.length &&
-      host.chatAttachments.length === 0 &&
-      (willRestoreDraft || !host.chatMessage.trim()),
+    opts.previousAttachments?.length &&
+    host.chatAttachments.length === 0 &&
+    (willRestoreDraft || !host.chatMessage.trim()),
   );
   if (restoreComposer) {
     if (willRestoreDraft) {
@@ -568,11 +572,26 @@ type ChatSendTimingPhase =
   | "pending-painted"
   | "request-start"
   | "ack"
+  | "first-assistant-visible"
+  | "terminal-before-delta"
   | "queued-busy"
   | "waiting-model"
   | "waiting-reconnect"
   | "failed";
 
+type ChatSendTimingEntry = {
+  runId: string;
+  sessionKey?: string;
+  agentId?: string;
+  sendAttempts: number;
+  sendState?: ChatQueueItem["sendState"];
+  submittedAtMs: number;
+  requestStartedAtMs?: number;
+  ackAtMs?: number;
+  ackStatus?: ChatSendAck["status"];
+  firstAssistantVisibleRecorded?: boolean;
+};
+
 function recordChatSendTiming(
   host: ChatHost,
   item: Pick<
@@ -603,6 +622,156 @@ function recordChatSendTiming(
   );
 }
 
+function ensureChatSendTimingEntries(host: ChatHost): Map<string, ChatSendTimingEntry> {
+  if (host.chatSendTimingsByRun) {
+    return host.chatSendTimingsByRun;
+  }
+  const entries = new Map<string, ChatSendTimingEntry>();
+  host.chatSendTimingsByRun = entries;
+  return entries;
+}
+
+function registerChatSendTiming(
+  host: ChatHost,
+  item: Pick<
+    ChatQueueItem,
+    "sendRunId" | "sessionKey" | "agentId" | "sendAttempts" | "sendState" | "sendSubmittedAtMs"
+  >,
+  runId: string,
+  requestStartedAtMs: number,
+) {
+  ensureChatSendTimingEntries(host).set(runId, {
+    runId,
+    sessionKey: item.sessionKey,
+    agentId: item.agentId,
+    sendAttempts: item.sendAttempts ?? 0,
+    sendState: item.sendState,
+    submittedAtMs: item.sendSubmittedAtMs ?? requestStartedAtMs,
+    requestStartedAtMs,
+  });
+}
+
+function updateChatSendAckTiming(
+  host: ChatHost,
+  requestedRunId: string,
+  ack: ChatSendAck,
+  item: Pick<
+    ChatQueueItem,
+    "sessionKey" | "agentId" | "sendAttempts" | "sendState" | "sendSubmittedAtMs"
+  >,
+  requestStartedAtMs: number,
+) {
+  const entries = ensureChatSendTimingEntries(host);
+  const existing = entries.get(requestedRunId);
+  const submittedAtMs = existing?.submittedAtMs ?? item.sendSubmittedAtMs ?? requestStartedAtMs;
+  const next: ChatSendTimingEntry = {
+    ...(existing ?? {
+      runId: ack.runId,
+      sessionKey: item.sessionKey,
+      agentId: item.agentId,
+      sendAttempts: item.sendAttempts ?? 0,
+      sendState: item.sendState,
+      submittedAtMs,
+      requestStartedAtMs,
+    }),
+    runId: ack.runId,
+    sessionKey: existing?.sessionKey ?? item.sessionKey,
+    agentId: existing?.agentId ?? item.agentId,
+    ackAtMs: controlUiNowMs(),
+    ackStatus: ack.status,
+  };
+  if (ack.runId !== requestedRunId) {
+    entries.delete(requestedRunId);
+  }
+  entries.set(ack.runId, next);
+}
+
+function chatEventHasVisibleTerminalPayload(payload: ChatEventPayload): boolean {
+  if (payload.state === "error" && payload.errorMessage?.trim()) {
+    return true;
+  }
+  return Boolean(payload.message && typeof payload.message === "object");
+}
+
+function resolveFirstAssistantTimingPhase(
+  host: ChatHost,
+  payload: ChatEventPayload,
+  entry: ChatSendTimingEntry,
+): Extract<ChatSendTimingPhase, "first-assistant-visible" | "terminal-before-delta"> | null {
+  if (entry.firstAssistantVisibleRecorded) {
+    return null;
+  }
+  if (payload.state === "delta") {
+    return typeof host.chatStream === "string" && host.chatStream.trim()
+      ? "first-assistant-visible"
+      : null;
+  }
+  if (payload.state === "final" || payload.state === "aborted" || payload.state === "error") {
+    return chatEventHasVisibleTerminalPayload(payload) ? "terminal-before-delta" : null;
+  }
+  return null;
+}
+
+export function recordFirstAssistantChatTiming(
+  host: ChatHost,
+  payload: ChatEventPayload | undefined,
+  handledState: ChatEventPayload["state"] | null,
+) {
+  if (!payload || !handledState || typeof payload.runId !== "string") {
+    return;
+  }
+  const runId = payload.runId.trim();
+  const entry = runId ? host.chatSendTimingsByRun?.get(runId) : undefined;
+  if (!entry) {
+    return;
+  }
+  const phase = resolveFirstAssistantTimingPhase(host, payload, entry);
+  if (!phase) {
+    if (payload.state === "final" || payload.state === "aborted" || payload.state === "error") {
+      host.chatSendTimingsByRun?.delete(runId);
+    }
+    return;
+  }
+
+  const eventAtMs = controlUiNowMs();
+  entry.firstAssistantVisibleRecorded = true;
+  scheduleControlUiAfterPaint(host, () => {
+    const paintedAtMs = controlUiNowMs();
+    recordControlUiPerformanceEvent(
+      host as Parameters<typeof recordControlUiPerformanceEvent>[0],
+      "control-ui.chat.send",
+      {
+        phase,
+        durationMs: roundedControlUiDurationMs(paintedAtMs - entry.submittedAtMs),
+        runId,
+        sessionKey: entry.sessionKey ?? payload.sessionKey,
+        agentId: entry.agentId ?? payload.agentId,
+        sendAttempts: entry.sendAttempts,
+        sendState: entry.sendState,
+        ackStatus: entry.ackStatus,
+        eventState: payload.state,
+        firstAssistantPaintMs: roundedControlUiDurationMs(paintedAtMs - eventAtMs),
+        ...(entry.requestStartedAtMs != null
+          ? {
+              requestToFirstAssistantEventMs: roundedControlUiDurationMs(
+                eventAtMs - entry.requestStartedAtMs,
+              ),
+            }
+          : {}),
+        ...(entry.ackAtMs != null
+          ? {
+              ackToFirstAssistantEventMs: roundedControlUiDurationMs(eventAtMs - entry.ackAtMs),
+            }
+          : {}),
+      },
+      { console: false, maxBufferedEventsForType: 40 },
+    );
+    if (phase === "terminal-before-delta") {
+      host.chatSendTimingsByRun?.delete(runId);
+    }
+  });
+}
+
 function shouldRecordPendingSendPaint(item: ChatQueueItem): boolean {
   return (
     typeof item.sendSubmittedAtMs === "number" &&
@@ -622,21 +791,18 @@ function schedulePendingSendPaintTiming(
   if (!sendRunId || startedAtMs == null) {
     return;
   }
-  scheduleControlUiAfterPaint(
-    host as Parameters<typeof scheduleControlUiAfterPaint>[0],
-    () => {
-      if (!visibleSessionMatches(host, sessionKey, item.agentId)) {
-        return;
-      }
-      const queued = readChatQueueForSession(host, sessionKey).find(
-        (entry) => entry.id === item.id && entry.sendRunId === sendRunId,
-      );
-      if (!queued || !shouldRecordPendingSendPaint(queued)) {
-        return;
-      }
-      recordChatSendTiming(host, queued, "pending-painted", startedAtMs);
-    },
-  );
+  scheduleControlUiAfterPaint(host as Parameters<typeof scheduleControlUiAfterPaint>[0], () => {
+    if (!visibleSessionMatches(host, sessionKey, item.agentId)) {
+      return;
+    }
+    const queued = readChatQueueForSession(host, sessionKey).find(
+      (entry) => entry.id === item.id && entry.sendRunId === sendRunId,
+    );
+    if (!queued || !shouldRecordPendingSendPaint(queued)) {
+      return;
+    }
+    recordChatSendTiming(host, queued, "pending-painted", startedAtMs);
+  });
 }
 
 function ensureQueuedSendState(
@@ -695,17 +861,19 @@ async function sendQueuedChatMessage(
   const runId = prepared.sendRunId ?? generateUUID();
   const startedAt = Date.now();
   const requestStartedAtMs = controlUiNowMs();
-  updateQueuedMessageForSession(host, sessionKey, id, (item) => ({
-    ...item,
-    sendAttempts: (item.sendAttempts ?? 0) + 1,
-    sendError: undefined,
-    sendRunId: runId,
-    sendState: "sending",
-    sendRequestStartedAtMs: requestStartedAtMs,
-    sessionKey,
-    agentId: prepared.agentId,
-  }));
-  recordChatSendTiming(host, prepared, "request-start", prepared.sendSubmittedAtMs);
+  const sendingItem =
+    updateQueuedMessageForSession(host, sessionKey, id, (item) => ({
+      ...item,
+      sendAttempts: (item.sendAttempts ?? 0) + 1,
+      sendError: undefined,
+      sendRunId: runId,
+      sendState: "sending",
+      sendRequestStartedAtMs: requestStartedAtMs,
+      sessionKey,
+      agentId: prepared.agentId,
+    })) ?? prepared;
+  registerChatSendTiming(host, sendingItem, runId, requestStartedAtMs);
+  recordChatSendTiming(host, sendingItem, "request-start", sendingItem.sendSubmittedAtMs);
   host.chatSending = true;
   const isVisibleSession = () => visibleSessionMatches(host, sessionKey, prepared.agentId);
   if (isVisibleSession()) {
@@ -723,7 +891,8 @@ async function sendQueuedChatMessage(
       sessionKey,
       agentId: prepared.agentId,
     });
-    recordChatSendTiming(host, prepared, "ack", prepared.sendSubmittedAtMs, {
+    updateChatSendAckTiming(host, runId, ack, sendingItem, requestStartedAtMs);
+    recordChatSendTiming(host, sendingItem, "ack", sendingItem.sendSubmittedAtMs, {
       ackStatus: ack.status,
       requestDurationMs: roundedControlUiDurationMs(controlUiNowMs() - requestStartedAtMs),
     });
diff --git a/ui/src/ui/app-gateway.node.test.ts b/ui/src/ui/app-gateway.node.test.ts
index 616be91c38dd..2e58251858a9 100644
--- a/ui/src/ui/app-gateway.node.test.ts
+++ b/ui/src/ui/app-gateway.node.test.ts
@@ -125,6 +125,7 @@ type TestGatewayHost = Parameters<typeof connectGateway>[0] & {
   chatSideResult: unknown;
   chatSideResultTerminalRuns: Set<string>;
   chatStream: string | null;
+  updateComplete?: Promise<unknown>;
   chatToolMessages: Record<string, unknown>[];
   activityEntries: ActivityEntry[];
   toolStreamById: Map<string, unknown>;
@@ -209,6 +210,18 @@ function connectHostGateway() {
   return { host, client };
 }
 
+function eventPayloads(host: TestGatewayHost, event: string): Array<Record<string, unknown>> {
+  const payloads: Array<Record<string, unknown>> = [];
+  for (const entry of host.eventLogBuffer) {
+    const candidate = entry as { event?: unknown; payload?: unknown };
+    if (candidate.event !== event || !candidate.payload || typeof candidate.payload !== "object") {
+      continue;
+    }
+    payloads.push(candidate.payload as Record<string, unknown>);
+  }
+  return payloads;
+}
+
 function emitToolResultEvent(client: GatewayClientMock) {
   client.emitEvent({
     event: "agent",
@@ -1104,6 +1117,67 @@ describe("connectGateway", () => {
     expect(loadChatHistoryMock).not.toHaveBeenCalled();
   });
 
+  it("records first assistant paint timing for tracked chat sends", async () => {
+    const { host, client } = connectHostGateway();
+    host.updateComplete = Promise.resolve();
+    host.chatRunId = "run-first-visible";
+    host.chatStream = "";
+    (
+      host as TestGatewayHost & {
+        chatSendTimingsByRun: Map<string, Record<string, unknown>>;
+      }
+    ).chatSendTimingsByRun = new Map([
+      [
+        "run-first-visible",
+        {
+          runId: "run-first-visible",
+          sessionKey: "main",
+          sendAttempts: 1,
+          sendState: "sending",
+          submittedAtMs: 100,
+          requestStartedAtMs: 125,
+          ackAtMs: 150,
+          ackStatus: "started",
+        },
+      ],
+    ]);
+
+    client.emitEvent({
+      event: "chat",
+      payload: {
+        runId: "run-first-visible",
+        sessionKey: "main",
+        state: "delta",
+        deltaText: "Hello",
+        message: {
+          role: "assistant",
+          content: [{ type: "text", text: "Hello" }],
+          timestamp: Date.now(),
+        },
+      },
+    });
+
+    await vi.waitFor(() =>
+      expect(
+        eventPayloads(host, "control-ui.chat.send").some(
+          (payload) => payload.phase === "first-assistant-visible",
+        ),
+      ).toBe(true),
+    );
+    const firstVisible = eventPayloads(host, "control-ui.chat.send").find(
+      (payload) => payload.phase === "first-assistant-visible",
+    );
+    expect(firstVisible).toMatchObject({
+      runId: "run-first-visible",
+      sessionKey: "main",
+      ackStatus: "started",
+      eventState: "delta",
+      sendState: "sending",
+    });
+    expect(firstVisible?.ackToFirstAssistantEventMs).toEqual(expect.any(Number));
+    expect(host.chatStream).toBe("Hello");
+  });
+
   it("renders session-scoped tool events for externally started runs", () => {
     const { host, client } = connectHostGateway();
 
diff --git a/ui/src/ui/app-gateway.ts b/ui/src/ui/app-gateway.ts
index baefb00112cf..44bbc683a563 100644
--- a/ui/src/ui/app-gateway.ts
+++ b/ui/src/ui/app-gateway.ts
@@ -9,6 +9,7 @@ import {
   flushChatQueueForEvent,
   hasReconnectableQueuedChatSends,
   markQueuedChatSendsWaitingForReconnect,
+  recordFirstAssistantChatTiming,
   refreshChatAvatar,
   scopedAgentListParamsForRefreshTarget,
   retryReconnectableQueuedChatSends,
@@ -895,6 +896,11 @@ function handleChatGatewayEvent(host: GatewayHost, payload: ChatEventPayload | u
   }
   const activeRunIdBeforeEvent = host.chatRunId;
   const state = handleChatEvent(host as unknown as ChatState, payload);
+  recordFirstAssistantChatTiming(
+    host as unknown as Parameters<typeof recordFirstAssistantChatTiming>[0],
+    payload,
+    state,
+  );
   const terminalEventIsForDifferentActiveRun = isEventForDifferentActiveRun(
     payload,
     activeRunIdBeforeEvent,
diff --git a/ui/src/ui/e2e/chat-flow.e2e.test.ts b/ui/src/ui/e2e/chat-flow.e2e.test.ts
index 769cc4a2f5b4..7459569117ab 100644
--- a/ui/src/ui/e2e/chat-flow.e2e.test.ts
+++ b/ui/src/ui/e2e/chat-flow.e2e.test.ts
@@ -56,6 +56,26 @@ async function chatThreadDistanceFromBottom(page: Page): Promise<number> {
   });
 }
 
+async function controlUiEventPayloads(
+  page: Page,
+  event: string,
+): Promise<Array<Record<string, unknown>>> {
+  return page.evaluate((eventName) => {
+    const app = document.querySelector("openclaw-app") as
+      | (Element & { eventLogBuffer?: unknown[] })
+      | null;
+    return (app?.eventLogBuffer ?? [])
+      .filter((entry): entry is { event: string; payload: Record<string, unknown> } => {
+        const candidate = entry as { event?: unknown; payload?: unknown };
+        return (
+          candidate.event === eventName &&
+          Boolean(candidate.payload && typeof candidate.payload === "object")
+        );
+      })
+      .map((entry) => entry.payload);
+  }, event);
+}
+
 function chatSessionListResponse() {
   return {
     count: 2,
@@ -280,6 +300,40 @@ describeControlUiE2e("Control UI mocked Gateway E2E", () => {
 
       const runId = requireString(params.idempotencyKey, "chat send idempotency key");
       await page.locator(".chat-thread").getByText(prompt).waitFor({ timeout: 10_000 });
+      await gateway.emitGatewayEvent("chat", {
+        deltaText: "First token visible.",
+        message: {
+          content: [{ text: "First token visible.", type: "text" }],
+          role: "assistant",
+          timestamp: Date.now(),
+        },
+        runId,
+        sessionKey: "main",
+        state: "delta",
+      });
+      await page.getByText("First token visible.").waitFor({ timeout: 10_000 });
+      await page.waitForFunction((expectedRunId) => {
+        const app = document.querySelector("openclaw-app") as
+          | (Element & { eventLogBuffer?: unknown[] })
+          | null;
+        return (app?.eventLogBuffer ?? []).some((entry) => {
+          const candidate = entry as {
+            event?: unknown;
+            payload?: { phase?: unknown; runId?: unknown };
+          };
+          return (
+            candidate.event === "control-ui.chat.send" &&
+            candidate.payload?.phase === "first-assistant-visible" &&
+            candidate.payload.runId === expectedRunId
+          );
+        });
+      }, runId);
+      const firstOutputEvents = await controlUiEventPayloads(page, "control-ui.chat.send");
+      expect(
+        firstOutputEvents.some(
+          (payload) => payload.phase === "first-assistant-visible" && payload.runId === runId,
+        ),
+      ).toBe(true);
       await gateway.resolveDeferred("chat.history", {
         messages: [],
         sessionId: "control-ui-e2e-session",