Use daemon timestamps for turn timing (#1033)

docs/architecture.md

@@ -207,6 +207,7 @@ initializing → idle ⇄ running
 
 - **AgentManager** is the source of truth for agent state and broadcasts updates to all subscribers
 - Timeline is append-only with epochs (each run starts a new epoch). Storage uses sequence numbers for client-side dedup; the default fetch page is 200 items
+- Timeline row `timestamp` values are canonical daemon-owned timestamps. Providers may supply original replay timestamps, but clients must not guess timestamp trust or hide time UI based on local clock heuristics.
 - Events stream to all subscribed clients in real time
 - Agent state persists to `$PASEO_HOME/agents/{cwd-with-dashes}/{agent-id}.json` (timeline rows live alongside the record)
 

packages/app/src/components/agent-stream-view.tsx

@@ -35,13 +35,14 @@ import { Check, ChevronDown, X } from "lucide-react-native";
 import { usePanelStore } from "@/stores/panel-store";
 import {
   AssistantMessage,
+  AssistantTurnFooter,
   SpeakMessage,
   UserMessage,
   ActivityLog,
   ToolCall,
   TodoListCard,
   CompactionMarker,
-  TurnCopyButton,
+  LiveElapsed,
   MessageOuterSpacingProvider,
   type InlinePathTarget,
 } from "./message";
@@ -89,6 +90,7 @@ import {
   WORKING_INDICATOR_CYCLE_MS,
   WORKING_INDICATOR_OFFSETS,
 } from "@/utils/working-indicator";
+import { findInFlightTurnStartedAt, findTurnHeaderForAssistantTurn } from "@/timeline/turn-time";
 import { isWeb } from "@/constants/platform";
 import { SPACING, type Theme } from "@/styles/theme";
 
@@ -274,6 +276,15 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
         ),
       [agent.status, baseRenderModel.segments.liveHead, streamRenderStrategy],
     );
+    const inFlightTurnStartedAt = useMemo(
+      () =>
+        findInFlightTurnStartedAt({
+          agentStatus: agent.status,
+          liveHead: baseRenderModel.segments.liveHead,
+          tail: streamItems,
+        }),
+      [agent.status, baseRenderModel.segments.liveHead, streamItems],
+    );
     useImperativeHandle(
       ref,
       () => ({
@@ -549,6 +560,12 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
               />
             );
 
+          case "turn_header":
+            // Purely a data carrier - duration renders next to the assistant
+            // turn's copy button (TurnCopyButtonSlot), and the in-flight
+            // ticker renders next to the WorkingIndicator dots.
+            return null;
+
           default:
             return null;
         }
@@ -583,7 +600,7 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
           item.kind === "assistant_message" && item.id === inlineWorkingIndicatorItemId;
         let footer: ReactNode = null;
         if (isRunningAssistantTurnFooter) {
-          footer = <InlineWorkingIndicatorSlot />;
+          footer = <InlineWorkingIndicatorSlot inFlightTurnStartedAt={inFlightTurnStartedAt} />;
         } else if (isEndOfAssistantTurn) {
           footer = (
             <TurnCopyButtonSlot strategy={streamRenderStrategy} items={items} startIndex={index} />
@@ -603,6 +620,7 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
         agent.status,
         streamRenderStrategy,
         inlineWorkingIndicatorItemId,
+        inFlightTurnStartedAt,
       ],
     );
 
@@ -628,10 +646,10 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
       () =>
         showAuxiliaryWorkingIndicator ? (
           <View style={stylesheet.bottomBarWrapper} testID="stream-working-indicator-auxiliary">
-            <WorkingIndicator />
+            <WorkingIndicator inFlightTurnStartedAt={inFlightTurnStartedAt} />
           </View>
         ) : null,
-      [showAuxiliaryWorkingIndicator],
+      [showAuxiliaryWorkingIndicator, inFlightTurnStartedAt],
     );
     const renderModel = useMemo<AgentStreamRenderModel>(() => {
       return {
@@ -803,7 +821,13 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
 export const AgentStreamView = memo(AgentStreamViewComponent);
 AgentStreamView.displayName = "AgentStreamView";
 
-function WorkingIndicator({ variant = "auxiliary" }: { variant?: "auxiliary" | "inline" }) {
+function WorkingIndicator({
+  variant = "auxiliary",
+  inFlightTurnStartedAt = null,
+}: {
+  variant?: "auxiliary" | "inline";
+  inFlightTurnStartedAt?: Date | null;
+}) {
   const progress = useSharedValue(0);
 
   useEffect(() => {
@@ -867,14 +891,25 @@ function WorkingIndicator({ variant = "auxiliary" }: { variant?: "auxiliary" | "
         <Animated.View style={dotTwoCombinedStyle} />
         <Animated.View style={dotThreeCombinedStyle} />
       </View>
+      {inFlightTurnStartedAt ? (
+        <LiveElapsed
+          startedAt={inFlightTurnStartedAt}
+          style={stylesheet.workingElapsed}
+          testID="turn-working-elapsed"
+        />
+      ) : null}
     </View>
   );
 }
 
-function InlineWorkingIndicatorSlot() {
+function InlineWorkingIndicatorSlot({
+  inFlightTurnStartedAt,
+}: {
+  inFlightTurnStartedAt: Date | null;
+}) {
   return (
     <View style={stylesheet.inlineTurnFooter} testID="turn-working-indicator">
-      <WorkingIndicator variant="inline" />
+      <WorkingIndicator variant="inline" inFlightTurnStartedAt={inFlightTurnStartedAt} />
     </View>
   );
 }
@@ -900,7 +935,17 @@ function TurnCopyButtonSlot({ strategy, items, startIndex }: TurnCopyButtonSlotP
       }),
     [strategy, items, startIndex],
   );
-  return <TurnCopyButton getContent={getContent} />;
+  const header = useMemo(
+    () => findTurnHeaderForAssistantTurn({ strategy, items, startIndex }),
+    [strategy, items, startIndex],
+  );
+  return (
+    <AssistantTurnFooter
+      getContent={getContent}
+      startedAt={header?.startedAt}
+      durationMs={header?.durationMs}
+    />
+  );
 }
 
 interface ToolCallSlotProps extends Omit<
@@ -1251,8 +1296,15 @@ const stylesheet = StyleSheet.create((theme) => ({
   },
   inlineWorkingIndicatorFrame: {
     height: 18,
+    flexDirection: "row",
     alignItems: "center",
-    justifyContent: "center",
+    justifyContent: "flex-start",
+    gap: theme.spacing[2],
+  },
+  workingElapsed: {
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.sm,
+    fontVariant: ["tabular-nums"],
   },
   workingIndicatorBubble: {
     flexDirection: "row",

packages/app/src/components/message.tsx

@@ -74,6 +74,7 @@ import { type AssistantFileLinkSource } from "@/utils/assistant-file-link-resolv
 import { useAssistantFileLinkResolver } from "@/hooks/use-assistant-file-link-resolver";
 import type { ToastApi } from "@/components/toast-host";
 import { splitMarkdownBlocks } from "@/utils/split-markdown-blocks";
+import { formatDuration, formatMessageTimestamp } from "@/utils/time";
 import {
   getAssistantImageLoadStateFromMetadata,
   getAssistantImageMetadata,
@@ -391,16 +392,25 @@ const userMessageStylesheet = StyleSheet.create((theme) => ({
     fontSize: theme.fontSize.sm,
   },
   copyButton: {
-    alignSelf: "flex-end",
     padding: theme.spacing[1],
+  },
+  trailingRow: {
+    alignSelf: "flex-end",
+    flexDirection: "row",
+    alignItems: "center",
+    gap: theme.spacing[2],
     marginTop: theme.spacing[2],
   },
-  copyButtonHidden: {
+  trailingRowHidden: {
     opacity: 0,
   },
-  copyButtonVisible: {
+  trailingRowVisible: {
     opacity: 1,
   },
+  timestampText: {
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.xs,
+  },
 }));
 
 function UserMessageAttachmentThumbnail({ image }: { image: UserMessageImageAttachment }) {
@@ -433,22 +443,26 @@ export const UserMessage = memo(function UserMessage({
   message,
   images = [],
   attachments = [],
-  timestamp: _timestamp,
+  timestamp,
   isFirstInGroup = true,
   isLastInGroup = true,
   disableOuterSpacing,
 }: UserMessageProps) {
   const isCompact = useIsCompactFormFactor();
-  const [messageHovered, setMessageHovered] = useState(false);
-  const [copyButtonHovered, setCopyButtonHovered] = useState(false);
+  const [isHovered, setIsHovered] = useState(false);
+  const [isCopyHovered, setIsCopyHovered] = useState(false);
   const resolvedDisableOuterSpacing = useDisableOuterSpacing(disableOuterSpacing);
   const hasText = message.trim().length > 0;
   const hasImages = images.length > 0;
   const hasAttachments = attachments.length > 0;
-  const showCopyButton = hasText && (isCompact || messageHovered || copyButtonHovered);
+  const showTrailingRow = hasText && (isCompact || isNative || isHovered || isCopyHovered);
+  const formattedTimestamp = useMemo(
+    () => formatMessageTimestamp(new Date(timestamp)),
+    [timestamp],
+  );
 
-  const handleHoverIn = useCallback(() => setMessageHovered(true), []);
-  const handleHoverOut = useCallback(() => setMessageHovered(false), []);
+  const handleHoverIn = useCallback(() => setIsHovered(true), []);
+  const handleHoverOut = useCallback(() => setIsHovered(false), []);
   const getMessageContent = useCallback(() => message, [message]);
 
   const containerStyle = useMemo(
@@ -476,66 +490,220 @@ export const UserMessage = memo(function UserMessage({
     ],
     [hasText],
   );
-  const copyButtonStyle = useMemo(
+  const trailingRowStyle = useMemo(
     () => [
-      userMessageStylesheet.copyButton,
-      showCopyButton
-        ? userMessageStylesheet.copyButtonVisible
-        : userMessageStylesheet.copyButtonHidden,
+      userMessageStylesheet.trailingRow,
+      showTrailingRow
+        ? userMessageStylesheet.trailingRowVisible
+        : userMessageStylesheet.trailingRowHidden,
     ],
-    [showCopyButton],
+    [showTrailingRow],
   );
 
   return (
     <View style={containerStyle}>
-      <Pressable
-        style={userMessageStylesheet.content}
-        onHoverIn={handleHoverIn}
-        onHoverOut={handleHoverOut}
-      >
-        <View style={userMessageStylesheet.bubble}>
-          {hasImages ? (
-            <View style={imagePreviewContainerStyle}>
-              {images.map((image) => (
-                <View key={image.id} style={userMessageStylesheet.imagePill}>
-                  <UserMessageAttachmentThumbnail image={image} />
-                </View>
-              ))}
-            </View>
-          ) : null}
-          {hasAttachments ? (
-            <View style={attachmentPreviewContainerStyle}>
-              {attachments.map((attachment, index) => (
-                <View
-                  key={`${attachment.type}:${"number" in attachment ? attachment.number : index}`}
-                  style={userMessageStylesheet.structuredAttachmentPill}
-                >
-                  <Text style={userMessageStylesheet.structuredAttachmentText} numberOfLines={1}>
-                    {getUserMessageAttachmentLabel(attachment)}
-                  </Text>
-                </View>
-              ))}
-            </View>
-          ) : null}
-          {hasText ? (
-            <Text selectable style={userMessageStylesheet.text}>
-              {message}
-            </Text>
-          ) : null}
-        </View>
+      <View style={userMessageStylesheet.content}>
+        <Pressable onHoverIn={handleHoverIn} onHoverOut={handleHoverOut}>
+          <View style={userMessageStylesheet.bubble}>
+            {hasImages ? (
+              <View style={imagePreviewContainerStyle}>
+                {images.map((image) => (
+                  <View key={image.id} style={userMessageStylesheet.imagePill}>
+                    <UserMessageAttachmentThumbnail image={image} />
+                  </View>
+                ))}
+              </View>
+            ) : null}
+            {hasAttachments ? (
+              <View style={attachmentPreviewContainerStyle}>
+                {attachments.map((attachment, index) => (
+                  <View
+                    key={`${attachment.type}:${"number" in attachment ? attachment.number : index}`}
+                    style={userMessageStylesheet.structuredAttachmentPill}
+                  >
+                    <Text style={userMessageStylesheet.structuredAttachmentText} numberOfLines={1}>
+                      {getUserMessageAttachmentLabel(attachment)}
+                    </Text>
+                  </View>
+                ))}
+              </View>
+            ) : null}
+            {hasText ? (
+              <Text selectable style={userMessageStylesheet.text}>
+                {message}
+              </Text>
+            ) : null}
+          </View>
+        </Pressable>
         {hasText ? (
-          <TurnCopyButton
-            getContent={getMessageContent}
-            containerStyle={copyButtonStyle}
-            accessibilityLabel="Copy message"
-            onHoverChange={setCopyButtonHovered}
-          />
+          <View style={trailingRowStyle} pointerEvents={showTrailingRow ? "auto" : "none"}>
+            <Text style={userMessageStylesheet.timestampText}>{formattedTimestamp}</Text>
+            <TurnCopyButton
+              getContent={getMessageContent}
+              containerStyle={userMessageStylesheet.copyButton}
+              accessibilityLabel="Copy message"
+              onHoverChange={setIsCopyHovered}
+            />
+          </View>
         ) : null}
-      </Pressable>
+      </View>
     </View>
   );
 });
 
+interface AssistantTurnFooterProps {
+  getContent: () => string;
+  startedAt?: Date;
+  durationMs?: number;
+}
+
+const assistantTurnFooterStylesheet = StyleSheet.create((theme) => ({
+  container: {
+    flexDirection: "row",
+    alignItems: "center",
+    gap: theme.spacing[2],
+    paddingVertical: theme.spacing[1],
+  },
+  copyButton: {
+    alignSelf: "center",
+    padding: theme.spacing[1],
+    paddingTop: theme.spacing[1],
+    marginTop: 0,
+  },
+  labelWrapper: {
+    position: "relative",
+  },
+  labelSizer: {
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.xs,
+    opacity: 0,
+  },
+  labelOverlay: {
+    position: "absolute",
+    top: 0,
+    left: 0,
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.xs,
+  },
+}));
+
+const TIMESTAMP_REVEAL_MS = 3000;
+
+/**
+ * Footer rendered next to the copy button at the end of an assistant turn.
+ * Always shows the turn duration; swaps to the start timestamp on hover (web)
+ * or tap (native). The hidden sizer keeps the label width stable while the
+ * visible text swaps.
+ */
+export const AssistantTurnFooter = memo(function AssistantTurnFooter({
+  getContent,
+  startedAt,
+  durationMs,
+}: AssistantTurnFooterProps) {
+  const [hovered, setHovered] = useState(false);
+  const [pressedReveal, setPressedReveal] = useState(false);
+  const revealTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  useEffect(() => {
+    return () => {
+      if (revealTimerRef.current) {
+        clearTimeout(revealTimerRef.current);
+        revealTimerRef.current = null;
+      }
+    };
+  }, []);
+
+  const durationLabel = useMemo(
+    () => (durationMs !== undefined ? `Worked for ${formatDuration(durationMs)}` : ""),
+    [durationMs],
+  );
+  const timestampLabel = useMemo(
+    () => (startedAt ? formatMessageTimestamp(startedAt) : ""),
+    [startedAt],
+  );
+
+  const canSwap = Boolean(timestampLabel);
+  const showTimestamp = canSwap && (isWeb ? hovered : pressedReveal);
+
+  const handleHoverIn = useCallback(() => setHovered(true), []);
+  const handleHoverOut = useCallback(() => setHovered(false), []);
+  const handlePress = useCallback(() => {
+    if (isWeb || !canSwap) return;
+    if (revealTimerRef.current) {
+      clearTimeout(revealTimerRef.current);
+    }
+    setPressedReveal((prev) => !prev);
+    revealTimerRef.current = setTimeout(() => {
+      setPressedReveal(false);
+      revealTimerRef.current = null;
+    }, TIMESTAMP_REVEAL_MS);
+  }, [canSwap]);
+
+  return (
+    <View style={assistantTurnFooterStylesheet.container}>
+      <TurnCopyButton
+        getContent={getContent}
+        containerStyle={assistantTurnFooterStylesheet.copyButton}
+      />
+      {durationLabel ? (
+        <Pressable
+          onPress={handlePress}
+          onHoverIn={handleHoverIn}
+          onHoverOut={handleHoverOut}
+          accessibilityRole={canSwap ? "button" : undefined}
+          accessibilityLabel={
+            canSwap ? `${durationLabel}, started ${timestampLabel}` : durationLabel
+          }
+        >
+          <View style={assistantTurnFooterStylesheet.labelWrapper}>
+            {/* Sizer reserves space for whichever label is longer so the
+                container width is stable across hover transitions. */}
+            <Text style={assistantTurnFooterStylesheet.labelSizer} aria-hidden>
+              {durationLabel.length >= timestampLabel.length ? durationLabel : timestampLabel}
+            </Text>
+            <Text style={assistantTurnFooterStylesheet.labelOverlay}>
+              {showTimestamp ? timestampLabel : durationLabel}
+            </Text>
+          </View>
+        </Pressable>
+      ) : null}
+    </View>
+  );
+});
+
+interface LiveElapsedProps {
+  startedAt: Date;
+  style?: StyleProp<TextStyle>;
+  testID?: string;
+}
+
+/**
+ * Ticks every 100ms to render an elapsed duration. Isolated from parents so
+ * only this component re-renders on each tick.
+ */
+export const LiveElapsed = memo(function LiveElapsed({
+  startedAt,
+  style,
+  testID,
+}: LiveElapsedProps) {
+  const startedAtMs = startedAt.getTime();
+  const [elapsedMs, setElapsedMs] = useState(() => Math.max(0, Date.now() - startedAtMs));
+
+  useEffect(() => {
+    setElapsedMs(Math.max(0, Date.now() - startedAtMs));
+    const handle = setInterval(() => {
+      setElapsedMs(Math.max(0, Date.now() - startedAtMs));
+    }, 100);
+    return () => clearInterval(handle);
+  }, [startedAtMs]);
+
+  return (
+    <Text style={style} testID={testID}>
+      {formatDuration(elapsedMs, { mode: "live" })}
+    </Text>
+  );
+});
+
 interface AssistantMessageProps {
   message: string;
   timestamp: number;

packages/app/src/timeline/session-stream-reducers.test.ts

@@ -1,3 +1,4 @@
+import invariant from "tiny-invariant";
 import { describe, expect, it } from "vitest";
 import type { AgentStreamEventPayload } from "@server/shared/messages";
 import type { StreamItem } from "@/types/stream";
@@ -218,6 +219,36 @@ describe("processTimelineResponse", () => {
     expect(result.sideEffects.some((e) => e.type === "flush_pending_updates")).toBe(true);
   });
 
+  it("uses the timeline entry timestamp as canonical", () => {
+    const result = processTimelineResponse({
+      ...baseTimelineInput,
+      payload: {
+        ...baseTimelineInput.payload,
+        reset: true,
+        startCursor: { seq: 1 },
+        endCursor: { seq: 2 },
+        entries: [
+          {
+            ...makeTimelineEntry(1, "hello", "user_message"),
+            timestamp: new Date("2025-01-01T12:00:03Z").toISOString(),
+          },
+          {
+            ...makeTimelineEntry(2, "reply"),
+            timestamp: new Date("2025-01-01T12:00:04Z").toISOString(),
+          },
+        ],
+      },
+    });
+
+    const user = result.tail.find((item) => item.kind === "user_message");
+    const header = result.tail.find((item) => item.kind === "turn_header");
+
+    expect(user?.timestamp.toISOString()).toBe("2025-01-01T12:00:03.000Z");
+    invariant(header?.kind === "turn_header");
+    expect(header.startedAt.toISOString()).toBe("2025-01-01T12:00:04.000Z");
+    expect(header.completedAt?.toISOString()).toBe("2025-01-01T12:00:04.000Z");
+  });
+
   it("sets cursor to null when reset=true but no cursors in payload", () => {
     const result = processTimelineResponse({
       ...baseTimelineInput,

packages/app/src/timeline/session-stream-reducers.ts

@@ -395,7 +395,10 @@ function applyTimelineIncrementalPath(args: {
   if (acceptedUnits.length > 0) {
     if (payload.direction === "before") {
       const olderTail = hydrateStreamState(
-        acceptedUnits.map(({ event, timestamp }) => ({ event, timestamp })),
+        acceptedUnits.map(({ event, timestamp }) => ({
+          event,
+          timestamp,
+        })),
         { source: "canonical" },
       );
       nextTail = mergePrependedCanonicalTail(olderTail, currentTail);
@@ -414,7 +417,9 @@ function applyTimelineIncrementalPath(args: {
     } else {
       nextTail = acceptedUnits.reduce<StreamItem[]>(
         (state, { event, timestamp }) =>
-          reduceStreamUpdate(state, event, timestamp, { source: "canonical" }),
+          reduceStreamUpdate(state, event, timestamp, {
+            source: "canonical",
+          }),
         currentTail,
       );
     }
@@ -482,7 +487,7 @@ export function processTimelineResponse(
   }));
 
   const toHydratedEvents = (
-    units: typeof timelineUnits,
+    units: TimelineUnit[],
   ): Array<{ event: AgentStreamEventPayload; timestamp: Date }> =>
     units.map(({ event, timestamp }) => ({ event, timestamp }));
 

packages/app/src/timeline/turn-time.ts

@@ -0,0 +1,147 @@
+import type { StreamItem, TurnHeaderItem, TurnHeaderOutcome } from "@/types/stream";
+
+export function appendLiveTurnHeader(state: StreamItem[], startedAt: Date): StreamItem[] {
+  const lastHeader = findLastTurnHeader(state);
+  if (lastHeader && lastHeader.completedAt === undefined) {
+    return state;
+  }
+  const header: TurnHeaderItem = {
+    kind: "turn_header",
+    id: `turn_${startedAt.getTime()}_${state.length.toString(36)}`,
+    timestamp: startedAt,
+    startedAt,
+    source: "live",
+  };
+  return [...state, header];
+}
+
+export function completeLastTurnHeader(
+  state: StreamItem[],
+  completedAt: Date,
+  outcome: TurnHeaderOutcome,
+): StreamItem[] {
+  for (let i = state.length - 1; i >= 0; i -= 1) {
+    const item = state[i];
+    if (item?.kind !== "turn_header") {
+      continue;
+    }
+    if (item.completedAt !== undefined) {
+      return state;
+    }
+    const updated: TurnHeaderItem = {
+      ...item,
+      completedAt,
+      durationMs: Math.max(0, completedAt.getTime() - item.startedAt.getTime()),
+      outcome,
+    };
+    const next = [...state];
+    next[i] = updated;
+    return next;
+  }
+  return state;
+}
+
+export function synthesizeMissingTurnHeaders(state: StreamItem[]): StreamItem[] {
+  const result: StreamItem[] = [];
+  let segment: StreamItem[] = [];
+  let needsHeader = true;
+
+  function flushSegment() {
+    if (segment.length === 0) {
+      return;
+    }
+    if (needsHeader) {
+      const first = segment[0];
+      const last = segment[segment.length - 1];
+      const startedAt = first.timestamp;
+      const completedAt = last.timestamp;
+      const header: TurnHeaderItem = {
+        kind: "turn_header",
+        id: `turn_derived_${startedAt.getTime()}_${result.length.toString(36)}`,
+        timestamp: startedAt,
+        startedAt,
+        completedAt,
+        durationMs: Math.max(0, completedAt.getTime() - startedAt.getTime()),
+        outcome: "completed",
+        source: "derived",
+      };
+      result.push(header);
+    }
+    result.push(...segment);
+    segment = [];
+  }
+
+  for (const item of state) {
+    if (item.kind === "user_message") {
+      flushSegment();
+      needsHeader = true;
+      result.push(item);
+      continue;
+    }
+    if (item.kind === "turn_header") {
+      flushSegment();
+      needsHeader = false;
+      result.push(item);
+      continue;
+    }
+    segment.push(item);
+  }
+
+  flushSegment();
+  return result;
+}
+
+export function findInFlightTurnStartedAt(params: {
+  agentStatus: string;
+  liveHead: StreamItem[];
+  tail: StreamItem[];
+}): Date | null {
+  if (params.agentStatus !== "running") {
+    return null;
+  }
+  const headStartedAt = findLastOpenTurnHeader(params.liveHead)?.startedAt;
+  if (headStartedAt) {
+    return headStartedAt;
+  }
+  return findLastOpenTurnHeader(params.tail)?.startedAt ?? null;
+}
+
+export interface TurnHeaderNeighborResolver {
+  getNeighborIndex(index: number, relation: "above" | "below"): number;
+}
+
+export function findTurnHeaderForAssistantTurn(params: {
+  strategy: TurnHeaderNeighborResolver;
+  items: StreamItem[];
+  startIndex: number;
+}): TurnHeaderItem | null {
+  let index = params.startIndex;
+  while (index >= 0 && index < params.items.length) {
+    const item = params.items[index];
+    if (!item) return null;
+    if (item.kind === "turn_header") return item;
+    if (item.kind === "user_message") return null;
+    index = params.strategy.getNeighborIndex(index, "above");
+  }
+  return null;
+}
+
+function findLastTurnHeader(state: StreamItem[]): TurnHeaderItem | null {
+  for (let i = state.length - 1; i >= 0; i -= 1) {
+    const item = state[i];
+    if (item?.kind === "turn_header") {
+      return item;
+    }
+  }
+  return null;
+}
+
+function findLastOpenTurnHeader(state: StreamItem[]): TurnHeaderItem | null {
+  for (let i = state.length - 1; i >= 0; i -= 1) {
+    const item = state[i];
+    if (item?.kind === "turn_header" && item.completedAt === undefined) {
+      return item;
+    }
+  }
+  return null;
+}

packages/app/src/types/stream.test.ts

@@ -1,4 +1,5 @@
 import assert from "node:assert/strict";
+import invariant from "tiny-invariant";
 import { describe, it } from "vitest";
 
 import {
@@ -325,14 +326,14 @@ describe("stream reducer canonical tool calls", () => {
       },
     ]);
 
-    assert.deepStrictEqual(
-      state.map((item) => (item.kind === "assistant_message" ? item.text : item.kind)),
-      ["First answer.", "Second answer."],
-    );
-    assert.deepStrictEqual(
-      state.map((item) => (item.kind === "assistant_message" ? item.messageId : null)),
-      ["msg-first", "msg-second"],
-    );
+    const messages = state.filter((item) => item.kind === "assistant_message");
+    assert.strictEqual(messages.length, 2);
+    const first = messages[0];
+    const second = messages[1];
+    invariant(first?.kind === "assistant_message");
+    invariant(second?.kind === "assistant_message");
+    assert.deepStrictEqual([first.text, second.text], ["First answer.", "Second answer."]);
+    assert.deepStrictEqual([first.messageId, second.messageId], ["msg-first", "msg-second"]);
   });
 
   it("merges adjacent assistant deltas when message ids match", () => {
@@ -347,13 +348,13 @@ describe("stream reducer canonical tool calls", () => {
       },
     ]);
 
-    assert.strictEqual(state.length, 1);
-    assert.strictEqual(state[0]?.kind, "assistant_message");
-    if (state[0]?.kind === "assistant_message") {
-      assert.strictEqual(state[0].text, "Hello");
-      assert.strictEqual(state[0].id, "msg-same");
-      assert.strictEqual(state[0].messageId, "msg-same");
-    }
+    const messages = state.filter((item) => item.kind === "assistant_message");
+    assert.strictEqual(messages.length, 1);
+    const first = messages[0];
+    invariant(first?.kind === "assistant_message");
+    assert.strictEqual(first.text, "Hello");
+    assert.strictEqual(first.id, "msg-same");
+    assert.strictEqual(first.messageId, "msg-same");
   });
 
   it("preserves old assistant merge behavior when message ids are absent", () => {
@@ -368,8 +369,11 @@ describe("stream reducer canonical tool calls", () => {
       },
     ]);
 
-    assert.strictEqual(state.length, 1);
-    assert.strictEqual(state[0]?.kind === "assistant_message" ? state[0].text : null, "Hello");
+    const messages = state.filter((item) => item.kind === "assistant_message");
+    assert.strictEqual(messages.length, 1);
+    const first = messages[0];
+    invariant(first?.kind === "assistant_message");
+    assert.strictEqual(first.text, "Hello");
   });
 
   it("merges running and completed events by callId", () => {
@@ -836,3 +840,113 @@ describe("stream reducer canonical tool calls", () => {
     );
   });
 });
+
+describe("turn headers", () => {
+  it("inserts a live header on turn_started and closes it on turn_completed", () => {
+    const startedAt = new Date("2025-01-01T12:00:00Z");
+    const completedAt = new Date("2025-01-01T12:00:05Z");
+
+    let state = reduceStreamUpdate([], { type: "turn_started", provider: "claude" }, startedAt);
+    state = reduceStreamUpdate(
+      state,
+      { type: "timeline", provider: "claude", item: { type: "assistant_message", text: "ok" } },
+      new Date("2025-01-01T12:00:02Z"),
+    );
+    state = reduceStreamUpdate(state, { type: "turn_completed", provider: "claude" }, completedAt);
+
+    const header = state.find((item) => item.kind === "turn_header");
+    invariant(header?.kind === "turn_header");
+    assert.strictEqual(header.source, "live");
+    assert.strictEqual(header.outcome, "completed");
+    assert.strictEqual(header.durationMs, 5_000);
+    assert.strictEqual(header.startedAt.getTime(), startedAt.getTime());
+    assert.strictEqual(header.completedAt?.getTime(), completedAt.getTime());
+  });
+
+  it("synthesizes a derived header during hydration when turn events are missing", () => {
+    const state = hydrateStreamState([
+      {
+        event: {
+          type: "timeline",
+          provider: "claude",
+          item: { type: "user_message", text: "hi" },
+        },
+        timestamp: new Date("2025-01-01T13:00:00Z"),
+      },
+      {
+        event: assistantTimeline("Working on it.", "claude", "msg-1"),
+        timestamp: new Date("2025-01-01T13:00:01Z"),
+      },
+      {
+        event: assistantTimeline("Done.", "claude", "msg-2"),
+        timestamp: new Date("2025-01-01T13:00:04Z"),
+      },
+    ]);
+
+    const headers = state.filter((item) => item.kind === "turn_header");
+    assert.strictEqual(headers.length, 1);
+    const [header] = headers;
+    invariant(header?.kind === "turn_header");
+    assert.strictEqual(header.source, "derived");
+    assert.strictEqual(header.outcome, "completed");
+    assert.strictEqual(header.durationMs, 3_000);
+    // Header should sit between the user message and the first assistant item.
+    const kinds = state.map((item) => item.kind);
+    assert.deepStrictEqual(kinds, [
+      "user_message",
+      "turn_header",
+      "assistant_message",
+      "assistant_message",
+    ]);
+  });
+
+  it("does not synthesize a derived header when a live header is already present", () => {
+    const startedAt = new Date("2025-01-01T14:00:00Z");
+    const state = hydrateStreamState([
+      {
+        event: {
+          type: "timeline",
+          provider: "claude",
+          item: { type: "user_message", text: "hi" },
+        },
+        timestamp: new Date("2025-01-01T13:59:59Z"),
+      },
+      { event: { type: "turn_started", provider: "claude" }, timestamp: startedAt },
+      {
+        event: assistantTimeline("ok", "claude", "msg-1"),
+        timestamp: new Date("2025-01-01T14:00:02Z"),
+      },
+    ]);
+
+    const headers = state.filter((item) => item.kind === "turn_header");
+    assert.strictEqual(headers.length, 1);
+    const header = headers[0];
+    invariant(header?.kind === "turn_header");
+    assert.strictEqual(header.source, "live");
+    assert.strictEqual(header.completedAt, undefined);
+  });
+
+  it("skips synthesis for turns with no assistant output", () => {
+    const state = hydrateStreamState([
+      {
+        event: {
+          type: "timeline",
+          provider: "claude",
+          item: { type: "user_message", text: "hi" },
+        },
+        timestamp: new Date("2025-01-01T15:00:00Z"),
+      },
+      {
+        event: {
+          type: "timeline",
+          provider: "claude",
+          item: { type: "user_message", text: "still there?" },
+        },
+        timestamp: new Date("2025-01-01T15:01:00Z"),
+      },
+    ]);
+
+    const headers = state.filter((item) => item.kind === "turn_header");
+    assert.strictEqual(headers.length, 0);
+  });
+});

packages/app/src/types/stream.ts

@@ -3,6 +3,11 @@ import type { AgentAttachment, AgentStreamEventPayload } from "@server/shared/me
 import type { AttachmentMetadata } from "@/attachments/types";
 import { extractTaskEntriesFromToolCall } from "../utils/tool-call-parsers";
 import { splitMarkdownBlocks } from "@/utils/split-markdown-blocks";
+import {
+  appendLiveTurnHeader,
+  completeLastTurnHeader,
+  synthesizeMissingTurnHeaders,
+} from "@/timeline/turn-time";
 
 /**
  * Simple hash function for deterministic ID generation
@@ -50,7 +55,21 @@ export type StreamItem =
   | ToolCallItem
   | TodoListItem
   | ActivityLogItem
-  | CompactionItem;
+  | CompactionItem
+  | TurnHeaderItem;
+
+export type TurnHeaderOutcome = "completed" | "failed" | "canceled";
+
+export interface TurnHeaderItem {
+  kind: "turn_header";
+  id: string;
+  timestamp: Date;
+  startedAt: Date;
+  completedAt?: Date;
+  durationMs?: number;
+  outcome?: TurnHeaderOutcome;
+  source: "live" | "derived";
+}
 
 export type UserMessageImageAttachment = AttachmentMetadata;
 
@@ -704,10 +723,15 @@ export function reduceStreamUpdate(
     case "timeline":
       return reduceTimelineEvent(state, event, timestamp, source);
     case "thread_started":
+      return finalizeActiveThoughts(state);
     case "turn_started":
+      return appendLiveTurnHeader(finalizeActiveThoughts(state), timestamp);
     case "turn_completed":
+      return completeLastTurnHeader(finalizeActiveThoughts(state), timestamp, "completed");
     case "turn_failed":
+      return completeLastTurnHeader(finalizeActiveThoughts(state), timestamp, "failed");
     case "turn_canceled":
+      return completeLastTurnHeader(finalizeActiveThoughts(state), timestamp, "canceled");
     case "permission_requested":
     case "permission_resolved":
     case "attention_required":
@@ -721,14 +745,17 @@ export function reduceStreamUpdate(
  * Hydrate stream state from a batch of AgentManager stream events
  */
 export function hydrateStreamState(
-  events: Array<{ event: AgentStreamEventPayload; timestamp: Date }>,
+  events: Array<{
+    event: AgentStreamEventPayload;
+    timestamp: Date;
+  }>,
   options?: { source?: StreamUpdateSource },
 ): StreamItem[] {
   const hydrated = events.reduce<StreamItem[]>((state, { event, timestamp }) => {
     return reduceStreamUpdate(state, event, timestamp, options);
   }, []);
 
-  return finalizeActiveThoughts(hydrated);
+  return synthesizeMissingTurnHeaders(finalizeActiveThoughts(hydrated));
 }
 
 /**
@@ -749,6 +776,16 @@ const STREAM_COMPLETION_EVENTS = new Set<AgentStreamEventPayload["type"]>([
   "turn_canceled",
 ]);
 
+function applyCompletionToTail(
+  tail: StreamItem[],
+  event: AgentStreamEventPayload,
+  timestamp: Date,
+  source: StreamUpdateSource,
+): StreamItem[] {
+  const finalized = finalizeActiveThoughts(tail);
+  return reduceStreamUpdate(finalized, event, timestamp, { source });
+}
+
 /**
  * Determine what kind of StreamItem an event would produce
  */
@@ -813,6 +850,28 @@ function getActiveAssistantHeadIndex(head: StreamItem[]): number {
   return -1;
 }
 
+function getTailAssistantToResume(params: {
+  incomingKind: StreamItem["kind"] | null;
+  event: AgentStreamEventPayload;
+  nextHead: StreamItem[];
+  tailAssistant: StreamItem | undefined;
+}): AssistantMessageItem | null {
+  if (params.incomingKind !== "assistant_message" || params.nextHead.length !== 0) {
+    return null;
+  }
+  if (params.tailAssistant?.kind !== "assistant_message") {
+    return null;
+  }
+  const incomingMessageId =
+    params.event.type === "timeline" && params.event.item.type === "assistant_message"
+      ? params.event.item.messageId
+      : undefined;
+  if (incomingMessageId !== undefined && params.tailAssistant.messageId !== incomingMessageId) {
+    return null;
+  }
+  return params.tailAssistant;
+}
+
 function promoteCompletedAssistantBlocks(params: { tail: StreamItem[]; head: StreamItem[] }): {
   tail: StreamItem[];
   head: StreamItem[];
@@ -986,8 +1045,7 @@ export function applyStreamEvent(params: {
   // Handle turn completion events - flush everything
   if (STREAM_COMPLETION_EVENTS.has(event.type)) {
     flushHead();
-    // Also finalize any remaining thoughts in tail
-    const finalized = finalizeActiveThoughts(nextTail);
+    const finalized = applyCompletionToTail(nextTail, event, timestamp, source);
     if (finalized !== nextTail) {
       nextTail = finalized;
       changedTail = true;
@@ -1002,21 +1060,17 @@ export function applyStreamEvent(params: {
     flushHead();
   }
 
-  if (incomingKind === "assistant_message" && nextHead.length === 0) {
-    const tailAssistant = nextTail.at(-1);
-    const incomingMessageId =
-      event.type === "timeline" && event.item.type === "assistant_message"
-        ? event.item.messageId
-        : undefined;
-    const shouldContinueTailAssistant =
-      tailAssistant?.kind === "assistant_message" &&
-      (incomingMessageId === undefined || tailAssistant.messageId === incomingMessageId);
-    if (shouldContinueTailAssistant) {
-      nextTail = nextTail.slice(0, -1);
-      nextHead = [tailAssistant];
-      changedTail = true;
-      changedHead = true;
-    }
+  const tailAssistant = getTailAssistantToResume({
+    incomingKind,
+    event,
+    nextHead,
+    tailAssistant: nextTail.at(-1),
+  });
+  if (tailAssistant) {
+    nextTail = nextTail.slice(0, -1);
+    nextHead = [tailAssistant];
+    changedTail = true;
+    changedHead = true;
   }
 
   // For streamable kinds, apply to head

packages/app/src/utils/time.test.ts

@@ -0,0 +1,63 @@
+import { describe, it, expect } from "vitest";
+import { formatDuration, formatMessageTimestamp } from "./time";
+
+describe("formatDuration", () => {
+  it("renders static durations as integers", () => {
+    expect(formatDuration(5_600)).toBe("5s");
+    expect(formatDuration(0)).toBe("0s");
+  });
+
+  it("renders 10s-60s as whole seconds", () => {
+    expect(formatDuration(47_000)).toBe("47s");
+    expect(formatDuration(10_400)).toBe("10s");
+  });
+
+  it("renders minutes and remainder seconds", () => {
+    expect(formatDuration(132_000)).toBe("2m 12s");
+    expect(formatDuration(120_000)).toBe("2m");
+  });
+
+  it("renders hours and remainder minutes", () => {
+    expect(formatDuration(3_900_000)).toBe("1h 5m");
+    expect(formatDuration(3_600_000)).toBe("1h");
+  });
+
+  it("guards against negative and NaN", () => {
+    expect(formatDuration(-1)).toBe("0s");
+    expect(formatDuration(Number.NaN)).toBe("0s");
+  });
+
+  it("keeps one decimal for live durations", () => {
+    expect(formatDuration(5_600, { mode: "live" })).toBe("5.6s");
+    expect(formatDuration(12_340, { mode: "live" })).toBe("12.3s");
+    expect(formatDuration(75_230, { mode: "live" })).toBe("1m 15.2s");
+    expect(formatDuration(0, { mode: "live" })).toBe("0.0s");
+  });
+});
+
+describe("formatMessageTimestamp", () => {
+  it("shows only time for same-day timestamps", () => {
+    const now = new Date(2026, 4, 14, 17, 30);
+    const date = new Date(2026, 4, 14, 12, 23);
+    const formatted = formatMessageTimestamp(date, now);
+    expect(formatted).toMatch(/12:23/);
+    expect(formatted).not.toMatch(/Thursday|Wednesday/);
+  });
+
+  it("includes weekday for timestamps within the last 6 days", () => {
+    // 2026-05-14 is a Thursday. 2026-05-11 is a Monday.
+    const now = new Date(2026, 4, 14, 17, 30);
+    const date = new Date(2026, 4, 11, 22, 12);
+    const formatted = formatMessageTimestamp(date, now);
+    expect(formatted).toMatch(/Monday/);
+    expect(formatted).toMatch(/10:12 PM|22:12/);
+  });
+
+  it("includes full date for older timestamps", () => {
+    const now = new Date(2026, 4, 14, 17, 30);
+    const date = new Date(2026, 3, 1, 9, 5);
+    const formatted = formatMessageTimestamp(date, now);
+    expect(formatted).toMatch(/Apr|April/);
+    expect(formatted).toMatch(/2026/);
+  });
+});

packages/app/src/utils/time.ts

@@ -35,3 +35,87 @@ export function formatTimeAgo(date: Date): string {
   const day = date.getDate();
   return `${month} ${day}`;
 }
+
+function isSameLocalDay(a: Date, b: Date): boolean {
+  return (
+    a.getFullYear() === b.getFullYear() &&
+    a.getMonth() === b.getMonth() &&
+    a.getDate() === b.getDate()
+  );
+}
+
+/**
+ * Format a chat-message timestamp for hover-revealed UI.
+ * - Same day: "10:11 PM"
+ * - Within ~6 days: "Wednesday 10:11 PM"
+ * - Older: "14 May 2026, 10:11 PM"
+ */
+export function formatMessageTimestamp(date: Date, now: Date = new Date()): string {
+  const time = date.toLocaleTimeString(undefined, {
+    hour: "numeric",
+    minute: "2-digit",
+  });
+
+  if (isSameLocalDay(date, now)) {
+    return time;
+  }
+
+  const diffMs = now.getTime() - date.getTime();
+  const diffDays = Math.floor(diffMs / (1000 * 60 * 60 * 24));
+  if (diffDays >= 0 && diffDays < 7) {
+    const weekday = date.toLocaleDateString(undefined, { weekday: "long" });
+    return `${weekday} ${time}`;
+  }
+
+  const dateLabel = date.toLocaleDateString(undefined, {
+    day: "numeric",
+    month: "short",
+    year: "numeric",
+  });
+  return `${dateLabel}, ${time}`;
+}
+
+type DurationFormatMode = "static" | "live";
+
+/**
+ * Format a duration as a compact human-readable string.
+ * - Static: integer units only
+ * - Live: always keep one decimal in the smallest displayed unit
+ */
+export function formatDuration(
+  durationMs: number,
+  options?: { mode?: DurationFormatMode },
+): string {
+  const mode = options?.mode ?? "static";
+  if (!Number.isFinite(durationMs) || durationMs < 0) {
+    return mode === "live" ? "0.0s" : "0s";
+  }
+  const totalSeconds = durationMs / 1000;
+
+  if (mode === "live") {
+    if (totalSeconds < 60) {
+      return `${totalSeconds.toFixed(1)}s`;
+    }
+    if (totalSeconds < 60 * 60) {
+      const minutes = Math.floor(totalSeconds / 60);
+      const seconds = totalSeconds - minutes * 60;
+      return `${minutes}m ${seconds.toFixed(1)}s`;
+    }
+    const hours = Math.floor(totalSeconds / (60 * 60));
+    const minutes = (totalSeconds - hours * 60 * 60) / 60;
+    return `${hours}h ${minutes.toFixed(1)}m`;
+  }
+
+  const wholeSeconds = Math.floor(totalSeconds);
+  if (wholeSeconds < 60) {
+    return `${wholeSeconds}s`;
+  }
+  const minutes = Math.floor(wholeSeconds / 60);
+  if (minutes < 60) {
+    const seconds = wholeSeconds % 60;
+    return seconds === 0 ? `${minutes}m` : `${minutes}m ${seconds}s`;
+  }
+  const hours = Math.floor(minutes / 60);
+  const remMinutes = minutes % 60;
+  return remMinutes === 0 ? `${hours}h` : `${hours}h ${remMinutes}m`;
+}

packages/server/src/server/agent/agent-manager.test.ts

@@ -5004,6 +5004,69 @@ test("hydrateTimeline keeps provider user_message items when no canonical user h
   expect(assistantMessages).toHaveLength(2);
 });
 
+test("hydrateTimeline preserves provider replay timestamps and marks missing ones untrusted", async () => {
+  const workdir = mkdtempSync(join(tmpdir(), "agent-manager-history-timestamps-"));
+  const storagePath = join(workdir, "agents");
+  const storage = new AgentStorage(storagePath, logger);
+
+  class TimestampedHistorySession extends TestAgentSession {
+    async *streamHistory(): AsyncGenerator<AgentStreamEvent> {
+      yield {
+        type: "timeline",
+        provider: this.provider,
+        timestamp: "2026-05-01T10:00:00.000Z",
+        item: { type: "user_message", text: "hello", messageId: "msg_history_1" },
+      };
+      yield {
+        type: "timeline",
+        provider: this.provider,
+        item: { type: "assistant_message", text: "no original timestamp" },
+      };
+    }
+  }
+
+  class TimestampedHistoryClient implements AgentClient {
+    readonly provider = "codex" as const;
+    readonly capabilities = TEST_CAPABILITIES;
+
+    async isAvailable(): Promise<boolean> {
+      return true;
+    }
+
+    async createSession(config: AgentSessionConfig): Promise<AgentSession> {
+      return new TimestampedHistorySession(config);
+    }
+
+    async resumeSession(): Promise<AgentSession> {
+      throw new Error("Not used in this test");
+    }
+  }
+
+  const manager = new AgentManager({
+    clients: {
+      codex: new TimestampedHistoryClient(),
+    },
+    registry: storage,
+    logger,
+    idFactory: () => "00000000-0000-4000-8000-000000000204",
+  });
+
+  const snapshot = await manager.createAgent({
+    provider: "codex",
+    cwd: workdir,
+  });
+
+  await manager.hydrateTimelineFromProvider(snapshot.id);
+  const timeline = manager.fetchTimeline(snapshot.id, { direction: "tail", limit: 0 }).rows;
+
+  expect(timeline).toHaveLength(2);
+  expect(timeline[0]).toMatchObject({
+    timestamp: "2026-05-01T10:00:00.000Z",
+    item: { type: "user_message", text: "hello", messageId: "msg_history_1" },
+  });
+  expect(timeline[1]?.timestamp).toEqual(expect.any(String));
+});
+
 test("hydrateTimeline suppresses only matching canonical user_message messageId", async () => {
   const workdir = mkdtempSync(join(tmpdir(), "agent-manager-history-partial-dedup-"));
   const storagePath = join(workdir, "agents");

packages/server/src/server/agent/agent-manager.ts

@@ -122,6 +122,7 @@ export type AgentManagerEvent =
       event: AgentStreamEvent;
       seq?: number;
       epoch?: string;
+      timestamp?: string;
     };
 
 export type AgentSubscriber = (event: AgentManagerEvent) => void;
@@ -1391,10 +1392,11 @@ export class AgentManager {
         this.dispatchStream(agent.id, event, {
           seq: row.seq,
           epoch: this.timelineStore.getEpoch(agent.id),
+          timestamp: row.timestamp,
         });
         return;
       }
-      this.dispatchStream(agent.id, event);
+      this.dispatchStream(agent.id, event, { timestamp: new Date().toISOString() });
     };
     void (async () => {
       try {
@@ -1436,6 +1438,7 @@ export class AgentManager {
       {
         seq: row.seq,
         epoch: this.timelineStore.getEpoch(agentId),
+        timestamp: row.timestamp,
       },
     );
     if (options?.emitState !== false) {
@@ -1457,6 +1460,7 @@ export class AgentManager {
       {
         seq: row.seq,
         epoch: this.timelineStore.getEpoch(agentId),
+        timestamp: row.timestamp,
       },
     );
     await this.persistSnapshot(agent);
@@ -1786,7 +1790,7 @@ export class AgentManager {
       const bufferedResolution = agent.bufferedPermissionResolutions.get(requestId);
       if (bufferedResolution) {
         agent.bufferedPermissionResolutions.delete(requestId);
-        this.dispatchStream(agent.id, bufferedResolution);
+        this.dispatchStream(agent.id, bufferedResolution, { timestamp: new Date().toISOString() });
       }
 
       return result;
@@ -1876,12 +1880,16 @@ export class AgentManager {
     // Clear any pending permissions that weren't cleaned up by handleStreamEvent.
     if (agent.pendingPermissions.size > 0) {
       for (const [requestId] of agent.pendingPermissions) {
-        this.dispatchStream(agent.id, {
-          type: "permission_resolved",
-          provider: agent.provider,
-          requestId,
-          resolution: { behavior: "deny", message: "Interrupted" },
-        });
+        this.dispatchStream(
+          agent.id,
+          {
+            type: "permission_resolved",
+            provider: agent.provider,
+            requestId,
+            resolution: { behavior: "deny", message: "Interrupted" },
+          },
+          { timestamp: new Date().toISOString() },
+        );
       }
       agent.pendingPermissions.clear();
       this.touchUpdatedAt(agent);
@@ -2587,7 +2595,11 @@ export class AgentManager {
         if (isDuplicateLegacyUserMessage(event.item, canonicalUserMessagesById)) {
           continue;
         }
-        this.recordTimeline(agent.id, event.item);
+        this.recordTimeline(
+          agent.id,
+          event.item,
+          event.timestamp ? { timestamp: event.timestamp } : undefined,
+        );
       }
     } catch {
       // ignore history failures
@@ -2663,7 +2675,7 @@ export class AgentManager {
     }
 
     if (!options?.fromHistory && flags.shouldDispatchEvent) {
-      this.dispatchStream(agent.id, event);
+      this.dispatchStream(agent.id, event, { timestamp: new Date().toISOString() });
     }
 
     this.traceHandleStreamEventEnd(agent, event, eventTurnId, flags);
@@ -2862,7 +2874,11 @@ export class AgentManager {
     }
 
     if (options?.fromHistory) {
-      this.recordTimeline(agent.id, event.item);
+      this.recordTimeline(
+        agent.id,
+        event.item,
+        event.timestamp ? { timestamp: event.timestamp } : undefined,
+      );
       flags.shouldDispatchEvent = false;
       flags.shouldNotifyWaiters = false;
       return;
@@ -3068,6 +3084,7 @@ export class AgentManager {
     this.dispatchStream(agentId, event, {
       seq: row.seq,
       epoch: this.timelineStore.getEpoch(agentId),
+      timestamp: row.timestamp,
     });
     return event;
   }
@@ -3108,6 +3125,7 @@ export class AgentManager {
       {
         seq: row.seq,
         epoch: this.timelineStore.getEpoch(agent.id),
+        timestamp: row.timestamp,
       },
     );
   }
@@ -3128,8 +3146,12 @@ export class AgentManager {
     return parts.join("\n\n");
   }
 
-  private recordTimeline(agentId: string, item: AgentTimelineItem): AgentTimelineRow {
-    const row = this.timelineStore.append(agentId, item);
+  private recordTimeline(
+    agentId: string,
+    item: AgentTimelineItem,
+    options?: { timestamp?: string },
+  ): AgentTimelineRow {
+    const row = this.timelineStore.append(agentId, item, options);
     this.enqueueDurableTimelineAppend(agentId, row);
     return row;
   }
@@ -3282,7 +3304,7 @@ export class AgentManager {
   private dispatchStream(
     agentId: string,
     event: AgentStreamEvent,
-    metadata?: { seq?: number; epoch?: string },
+    metadata?: { seq?: number; epoch?: string; timestamp?: string },
   ): void {
     const agent = this.agents.get(agentId);
     this.logger.trace(

packages/server/src/server/agent/agent-sdk-types.ts

@@ -346,7 +346,13 @@ export type AgentStreamEvent =
       turnId?: string;
     }
   | { type: "turn_canceled"; provider: AgentProvider; reason: string; turnId?: string }
-  | { type: "timeline"; item: AgentTimelineItem; provider: AgentProvider; turnId?: string }
+  | {
+      type: "timeline";
+      item: AgentTimelineItem;
+      provider: AgentProvider;
+      turnId?: string;
+      timestamp?: string;
+    }
   | {
       type: "permission_requested";
       provider: AgentProvider;

packages/server/src/server/agent/provider-history-timestamps.test.ts

@@ -0,0 +1,23 @@
+import { describe, expect, test } from "vitest";
+
+import { normalizeProviderReplayTimestamp } from "./provider-history-timestamps.js";
+
+describe("normalizeProviderReplayTimestamp", () => {
+  test("preserves valid string timestamps after trimming", () => {
+    expect(normalizeProviderReplayTimestamp(" 2026-05-01T10:00:00.000Z ")).toBe(
+      "2026-05-01T10:00:00.000Z",
+    );
+  });
+
+  test("converts numeric second and millisecond timestamps to ISO", () => {
+    expect(normalizeProviderReplayTimestamp(1_778_762_475)).toBe("2026-05-14T12:41:15.000Z");
+    expect(normalizeProviderReplayTimestamp(1_778_762_475_873)).toBe("2026-05-14T12:41:15.873Z");
+  });
+
+  test("returns null for missing or invalid timestamps", () => {
+    expect(normalizeProviderReplayTimestamp(undefined)).toBeNull();
+    expect(normalizeProviderReplayTimestamp("not a timestamp")).toBeNull();
+    expect(normalizeProviderReplayTimestamp(Number.NaN)).toBeNull();
+    expect(normalizeProviderReplayTimestamp(Number.POSITIVE_INFINITY)).toBeNull();
+  });
+});

packages/server/src/server/agent/provider-history-timestamps.ts

@@ -0,0 +1,17 @@
+export function normalizeProviderReplayTimestamp(value: unknown): string | null {
+  if (typeof value === "string") {
+    const timestamp = value.trim();
+    if (!timestamp || Number.isNaN(Date.parse(timestamp))) {
+      return null;
+    }
+    return timestamp;
+  }
+
+  if (typeof value !== "number" || !Number.isFinite(value)) {
+    return null;
+  }
+
+  const timestampMs = value > 1_000_000_000_000 ? value : value * 1000;
+  const date = new Date(timestampMs);
+  return Number.isNaN(date.getTime()) ? null : date.toISOString();
+}

packages/server/src/server/agent/providers/claude/agent.ts

@@ -41,6 +41,7 @@ import {
 import { appendOrReplaceGrowingAssistantMessage, runProviderTurn } from "../provider-runner.js";
 import { renderPromptAttachmentAsText } from "../../prompt-attachments.js";
 import { claudeQuery, type ClaudeOptions, type ClaudeQueryFactory } from "./query.js";
+import { normalizeProviderReplayTimestamp } from "../../provider-history-timestamps.js";
 
 import {
   getAgentStreamEventTurnId,
@@ -185,6 +186,11 @@ interface AsyncMessageInput<T> {
   iterable: AsyncIterable<T>;
 }
 
+interface PersistedTimelineEntry {
+  item: AgentTimelineItem;
+  timestamp?: string;
+}
+
 const CLAUDE_CAPABILITIES: AgentCapabilityFlags = {
   supportsStreaming: true,
   supportsSessionPersistence: true,
@@ -1548,7 +1554,7 @@ class ClaudeAgentSession implements AgentSession {
   private readonly sidechainTracker = new ClaudeSidechainTracker({
     getToolInput: (toolUseId) => this.toolUseCache.get(toolUseId)?.input ?? null,
   });
-  private persistedHistory: AgentTimelineItem[] = [];
+  private persistedHistory: PersistedTimelineEntry[] = [];
   private historyPending = false;
   private turnState: TurnState = "idle";
   private nextTurnOrdinal = 1;
@@ -1756,8 +1762,13 @@ class ClaudeAgentSession implements AgentSession {
     const history = this.persistedHistory;
     this.persistedHistory = [];
     this.historyPending = false;
-    for (const item of history) {
-      yield { type: "timeline", item, provider: "claude" };
+    for (const entry of history) {
+      yield {
+        type: "timeline",
+        item: entry.item,
+        provider: "claude",
+        timestamp: entry.timestamp,
+      };
     }
   }
 
@@ -2142,9 +2153,9 @@ class ClaudeAgentSession implements AgentSession {
       pushUnique(historyIds[idx]);
     }
     for (let idx = this.persistedHistory.length - 1; idx >= 0; idx -= 1) {
-      const item = this.persistedHistory[idx];
-      if (item?.type === "user_message") {
-        pushUnique(item.messageId);
+      const entry = this.persistedHistory[idx];
+      if (entry?.item.type === "user_message") {
+        pushUnique(entry.item.messageId);
       }
     }
     for (let idx = this.userMessageIds.length - 1; idx >= 0; idx -= 1) {
@@ -3624,7 +3635,7 @@ class ClaudeAgentSession implements AgentSession {
       return;
     }
 
-    const timeline: AgentTimelineItem[] = [];
+    const timeline: PersistedTimelineEntry[] = [];
     for (const line of content.split(/\r?\n/)) {
       this.ingestPersistedHistoryLine(line, timeline);
     }
@@ -3635,7 +3646,7 @@ class ClaudeAgentSession implements AgentSession {
     }
   }
 
-  private ingestPersistedHistoryLine(line: string, timeline: AgentTimelineItem[]): void {
+  private ingestPersistedHistoryLine(line: string, timeline: PersistedTimelineEntry[]): void {
     const trimmed = line.trim();
     if (!trimmed) {
       return;
@@ -3660,9 +3671,15 @@ class ClaudeAgentSession implements AgentSession {
       this.rememberUserMessageId(entry.uuid);
     }
 
+    const historyTimestamp = normalizeProviderReplayTimestamp(entry.timestamp);
     const items = this.convertHistoryEntry(entry);
     if (items.length > 0) {
-      timeline.push(...items);
+      timeline.push(
+        ...items.map((item) => ({
+          item,
+          timestamp: historyTimestamp ?? undefined,
+        })),
+      );
     }
   }
 

packages/server/src/server/agent/providers/codex-app-server-agent.test.ts

@@ -1370,10 +1370,12 @@ describe("Codex app-server provider", () => {
                     type: "agentMessage",
                     id: "message-history",
                     text: "History loaded.",
+                    timestamp: "2026-05-01T10:00:00.000Z",
                   },
                   {
                     type: "contextCompaction",
                     id: "compact-history",
+                    createdAt: "2026-05-01T10:00:01.000Z",
                   },
                 ],
               },
@@ -1397,6 +1399,7 @@ describe("Codex app-server provider", () => {
       {
         type: "timeline",
         provider: "codex",
+        timestamp: "2026-05-01T10:00:00.000Z",
         item: {
           type: "assistant_message",
           text: "History loaded.",
@@ -1406,6 +1409,7 @@ describe("Codex app-server provider", () => {
       {
         type: "timeline",
         provider: "codex",
+        timestamp: "2026-05-01T10:00:01.000Z",
         item: {
           type: "compaction",
           status: "completed",

packages/server/src/server/agent/providers/codex-app-server-agent.ts

@@ -64,6 +64,7 @@ import {
   renderProviderImageOutputAsAssistantMarkdown,
   type ProviderImageOutput,
 } from "./provider-image-output.js";
+import { normalizeProviderReplayTimestamp } from "../provider-history-timestamps.js";
 import {
   formatDiagnosticStatus,
   formatProviderDiagnostic,
@@ -358,6 +359,11 @@ interface CodexConfiguredDefaults {
   thinkingOptionId?: string;
 }
 
+interface PersistedTimelineEntry {
+  item: AgentTimelineItem;
+  timestamp?: string;
+}
+
 function mergeCodexConfiguredDefaults(
   primary: CodexConfiguredDefaults,
   fallback: CodexConfiguredDefaults,
@@ -1444,6 +1450,18 @@ function firstStringField(
   return null;
 }
 
+function readCodexHistoryTimestamp(item: unknown): string | null {
+  const record = toObjectRecord(item);
+  if (!record) {
+    return null;
+  }
+  return (
+    normalizeProviderReplayTimestamp(record.timestamp) ??
+    normalizeProviderReplayTimestamp(record.createdAt) ??
+    normalizeProviderReplayTimestamp(record.created_at)
+  );
+}
+
 function codexImageOutputFromResult(result: unknown): ProviderImageOutput | null {
   if (typeof result === "string") {
     const trimmed = result.trim();
@@ -1591,14 +1609,18 @@ async function loadCodexThreadHistoryTimeline(params: {
   threadId: string;
   cwd: string | null;
   requestThread: CodexThreadReadRequest;
-}): Promise<AgentTimelineItem[]> {
+}): Promise<PersistedTimelineEntry[]> {
   const response = await requestCodexThreadHistory(params.requestThread, params.threadId);
-  const timeline: AgentTimelineItem[] = [];
+  const timeline: PersistedTimelineEntry[] = [];
   for (const turn of response.thread.turns) {
     for (const item of turn.items) {
       const timelineItem = threadItemToTimeline(item, { cwd: params.cwd });
       if (timelineItem) {
-        timeline.push(timelineItem);
+        const timestamp = readCodexHistoryTimestamp(item);
+        timeline.push({
+          item: timelineItem,
+          timestamp: timestamp ?? undefined,
+        });
       }
     }
   }
@@ -2678,7 +2700,7 @@ class CodexAppServerAgentSession implements AgentSession {
   private serviceTier: "fast" | null = null;
   private planModeEnabled = false;
   private historyPending = false;
-  private persistedHistory: AgentTimelineItem[] = [];
+  private persistedHistory: PersistedTimelineEntry[] = [];
   private pendingPermissions = new Map<string, AgentPermissionRequest>();
   private pendingPermissionHandlers = new Map<
     string,
@@ -3334,8 +3356,13 @@ class CodexAppServerAgentSession implements AgentSession {
     const history = this.persistedHistory;
     this.persistedHistory = [];
     this.historyPending = false;
-    for (const item of history) {
-      yield { type: "timeline", provider: CODEX_PROVIDER, item };
+    for (const entry of history) {
+      yield {
+        type: "timeline",
+        provider: CODEX_PROVIDER,
+        item: entry.item,
+        timestamp: entry.timestamp,
+      };
     }
   }
 
@@ -5151,7 +5178,7 @@ export class CodexAppServerAgentClient implements AgentClient {
           const threadId = typeof thread.id === "string" ? thread.id : "";
           const cwd = typeof thread.cwd === "string" ? thread.cwd : process.cwd();
           const title = typeof thread.preview === "string" ? thread.preview : null;
-          let timeline: AgentTimelineItem[] = [];
+          let timeline: PersistedTimelineEntry[] = [];
 
           try {
             timeline = await loadCodexThreadHistoryTimeline({
@@ -5186,7 +5213,7 @@ export class CodexAppServerAgentClient implements AgentClient {
                 threadId,
               },
             },
-            timeline,
+            timeline: timeline.map((entry) => entry.item),
           };
         }),
       );

packages/server/src/server/agent/providers/opencode-agent.test.ts

@@ -833,6 +833,144 @@ describe("OpenCode adapter startTurn error handling", () => {
     expect(fakeClient.session.delete).not.toHaveBeenCalled();
   });
 
+  test("streamHistory preserves OpenCode replay timestamps from message and part times", async () => {
+    const fakeClient = {
+      session: {
+        messages: vi.fn().mockResolvedValue({
+          data: [
+            {
+              info: {
+                id: "msg_user",
+                sessionID: "ses_unit_test",
+                role: "user",
+                time: { created: 1778762475873 },
+              },
+              parts: [
+                {
+                  id: "prt_user",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_user",
+                  type: "text",
+                  text: "Reply with exactly: probe ok",
+                },
+              ],
+            },
+            {
+              info: {
+                id: "msg_assistant",
+                sessionID: "ses_unit_test",
+                role: "assistant",
+                time: { created: 1778762475884, completed: 1778762489358 },
+              },
+              parts: [
+                {
+                  id: "prt_reasoning",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_assistant",
+                  type: "reasoning",
+                  text: "thinking",
+                  time: { start: 1778762482953, end: 1778762483610 },
+                },
+                {
+                  id: "prt_text",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_assistant",
+                  type: "text",
+                  text: "probe ok",
+                  time: { start: 1778762483612, end: 1778762489351 },
+                },
+              ],
+            },
+          ],
+          error: undefined,
+        }),
+      },
+    } as never;
+
+    const session = new __openCodeInternals.OpenCodeAgentSession(
+      { provider: "opencode", cwd: "/tmp/test" },
+      fakeClient,
+      "ses_unit_test",
+      createTestLogger(),
+      "/tmp/opencode-storage",
+    );
+
+    const history: AgentStreamEvent[] = [];
+    for await (const event of session.streamHistory()) {
+      history.push(event);
+    }
+
+    expect(history).toEqual([
+      {
+        type: "timeline",
+        provider: "opencode",
+        timestamp: "2026-05-14T12:41:15.873Z",
+        item: { type: "user_message", text: "Reply with exactly: probe ok" },
+      },
+      {
+        type: "timeline",
+        provider: "opencode",
+        timestamp: "2026-05-14T12:41:22.953Z",
+        item: { type: "reasoning", text: "thinking" },
+      },
+      {
+        type: "timeline",
+        provider: "opencode",
+        timestamp: "2026-05-14T12:41:23.612Z",
+        item: { type: "assistant_message", text: "probe ok" },
+      },
+    ]);
+  });
+
+  test("streamHistory omits replay timestamps when OpenCode omits times", async () => {
+    const fakeClient = {
+      session: {
+        messages: vi.fn().mockResolvedValue({
+          data: [
+            {
+              info: {
+                id: "msg_assistant",
+                sessionID: "ses_unit_test",
+                role: "assistant",
+              },
+              parts: [
+                {
+                  id: "prt_text",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_assistant",
+                  type: "text",
+                  text: "no clocks here",
+                },
+              ],
+            },
+          ],
+          error: undefined,
+        }),
+      },
+    } as never;
+
+    const session = new __openCodeInternals.OpenCodeAgentSession(
+      { provider: "opencode", cwd: "/tmp/test" },
+      fakeClient,
+      "ses_unit_test",
+      createTestLogger(),
+      "/tmp/opencode-storage",
+    );
+
+    const history: AgentStreamEvent[] = [];
+    for await (const event of session.streamHistory()) {
+      history.push(event);
+    }
+
+    expect(history).toEqual([
+      {
+        type: "timeline",
+        provider: "opencode",
+        item: { type: "assistant_message", text: "no clocks here" },
+      },
+    ]);
+  });
+
   test("emits turn_failed when client.session.promptAsync throws synchronously", async () => {
     // Yield the server-connected event, then park forever. The adapter waits
     // for that first event before sending the prompt.

packages/server/src/server/agent/providers/opencode-agent.ts

@@ -62,6 +62,7 @@ import {
   type OpenCodeRuntime,
   type OpenCodeServerAcquisition,
 } from "./opencode/runtime.js";
+import { normalizeProviderReplayTimestamp } from "../provider-history-timestamps.js";
 
 const OPENCODE_CAPABILITIES: AgentCapabilityFlags = {
   supportsStreaming: true,
@@ -899,6 +900,71 @@ function getOpenCodePartTimestamp(part: OpenCodeStoredPart): number {
   return part.time?.start ?? part.time?.end ?? 0;
 }
 
+function resolveOpenCodeReplayTimestamp(params: {
+  message: { time?: { created?: number; completed?: number } | undefined };
+  part?: unknown;
+}): string | null {
+  const timedPart = params.part as
+    | { time?: { start?: number; end?: number } | undefined }
+    | undefined;
+  const partTimestamp =
+    timedPart?.time?.start ??
+    timedPart?.time?.end ??
+    params.message.time?.created ??
+    params.message.time?.completed;
+  return normalizeProviderReplayTimestamp(partTimestamp);
+}
+
+function buildOpenCodeReplayTimelineEvent(params: {
+  item: AgentTimelineItem;
+  message: { time?: { created?: number; completed?: number } | undefined };
+  part?: unknown;
+}): Extract<AgentStreamEvent, { type: "timeline" }> {
+  const timestamp = resolveOpenCodeReplayTimestamp({
+    message: params.message,
+    part: params.part,
+  });
+  return {
+    type: "timeline",
+    provider: "opencode",
+    item: params.item,
+    ...(timestamp ? { timestamp } : {}),
+  };
+}
+
+function buildOpenCodeReplayPartTimelineEvent(params: {
+  part: OpenCodePart;
+  message: { structured?: unknown; time?: { created?: number; completed?: number } | undefined };
+}): Extract<AgentStreamEvent, { type: "timeline" }> | null {
+  const { part, message } = params;
+  if (part.type === "text" && part.text) {
+    return buildOpenCodeReplayTimelineEvent({
+      item: { type: "assistant_message", text: part.text },
+      message,
+      part,
+    });
+  }
+  if (part.type === "reasoning" && part.text) {
+    return buildOpenCodeReplayTimelineEvent({
+      item: { type: "reasoning", text: part.text },
+      message,
+      part,
+    });
+  }
+  if (part.type !== "tool") {
+    return null;
+  }
+  const parsedToolPart = OpencodeToolPartToTimelineItemSchema.safeParse(part);
+  if (!parsedToolPart.success || !parsedToolPart.data) {
+    return null;
+  }
+  return buildOpenCodeReplayTimelineEvent({
+    item: parsedToolPart.data,
+    message,
+    part,
+  });
+}
+
 export const __openCodeInternals = {
   buildOpenCodePromptParts,
   buildOpenCodeModelContextWindowLookup,
@@ -2842,53 +2908,30 @@ class OpenCodeAgentSession implements AgentSession {
           .join("");
 
         if (text) {
-          yield {
-            type: "timeline",
-            provider: "opencode",
+          yield buildOpenCodeReplayTimelineEvent({
             item: { type: "user_message", text },
-          };
+            message: info,
+          });
         }
       } else {
         let emittedAssistantText = false;
         for (const part of parts) {
           if (part.type === "text" && part.text) {
             emittedAssistantText = true;
-            yield {
-              type: "timeline",
-              provider: "opencode",
-              item: { type: "assistant_message", text: part.text },
-            };
-            continue;
           }
-          if (part.type === "reasoning" && part.text) {
-            yield {
-              type: "timeline",
-              provider: "opencode",
-              item: { type: "reasoning", text: part.text },
-            };
-            continue;
-          }
-          if (part.type !== "tool") {
-            continue;
-          }
-          const parsedToolPart = OpencodeToolPartToTimelineItemSchema.safeParse(part);
-          if (parsedToolPart.success && parsedToolPart.data) {
-            yield {
-              type: "timeline",
-              provider: "opencode",
-              item: parsedToolPart.data,
-            };
+          const event = buildOpenCodeReplayPartTimelineEvent({ part, message: info });
+          if (event) {
+            yield event;
           }
         }
 
         if (!emittedAssistantText) {
           const text = stringifyStructuredAssistantMessage(info.structured);
           if (text) {
-            yield {
-              type: "timeline",
-              provider: "opencode",
+            yield buildOpenCodeReplayTimelineEvent({
               item: { type: "assistant_message", text },
-            };
+              message: info,
+            });
           }
         }
       }

packages/server/src/server/agent/timeline-projection.ts

@@ -142,6 +142,7 @@ function collapseToolLifecycle(entries: readonly WorkingEntry[]): WorkingEntry[]
     output[existingIndex] = {
       ...existing,
       item: mergedItem,
+      timestamp: entry.timestamp,
       seqEnd: Math.max(existing.seqEnd, entry.seqEnd),
       sourceSeqRanges: mergedRanges,
       collapsed,
@@ -181,6 +182,7 @@ function mergeReasoningChunks(entries: readonly WorkingEntry[]): WorkingEntry[]
         type: "reasoning",
         text: `${previousReasoning.text}${entryReasoning.text}`,
       },
+      timestamp: entry.timestamp,
       seqEnd: entry.seqEnd,
       sourceSeqRanges: mergeSeqRanges(previous.sourceSeqRanges, entry.sourceSeqRanges),
       collapsed: Array.from(collapsedKinds),
@@ -231,6 +233,7 @@ function mergeAssistantChunks(entries: readonly WorkingEntry[]): WorkingEntry[]
         text: `${previousAssistant.text}${entryAssistant.text}`,
         ...(previousAssistant.messageId ? { messageId: previousAssistant.messageId } : {}),
       },
+      timestamp: entry.timestamp,
       seqEnd: entry.seqEnd,
       sourceSeqRanges: mergeSeqRanges(previous.sourceSeqRanges, entry.sourceSeqRanges),
       collapsed: Array.from(collapsedKinds),

packages/server/src/server/session.ts

@@ -96,6 +96,7 @@ import type {
 import { AgentManager } from "./agent/agent-manager.js";
 import { ProviderSnapshotManager, resolveSnapshotCwd } from "./agent/provider-snapshot-manager.js";
 import type {
+  AgentManagerEvent,
   AgentTimelineCursor,
   AgentTimelineFetchDirection,
   ManagedAgent,
@@ -1277,20 +1278,8 @@ export class Session {
         // Reduce bandwidth/CPU on mobile: only forward high-frequency agent stream events
         // for the focused agent, with a short grace window while backgrounded.
         // History catch-up is handled via pull-based `fetch_agent_timeline_request`.
-        const activity = this.clientActivity;
-        if (activity?.deviceType === "mobile") {
-          if (!activity.focusedAgentId) {
-            return;
-          }
-          if (activity.focusedAgentId !== event.agentId) {
-            return;
-          }
-          if (!activity.appVisible) {
-            const hiddenForMs = Date.now() - activity.appVisibilityChangedAt.getTime();
-            if (hiddenForMs >= this.MOBILE_BACKGROUND_STREAM_GRACE_MS) {
-              return;
-            }
-          }
+        if (this.shouldSkipAgentStreamForward(event.agentId)) {
+          return;
         }
 
         const serializedEvent = serializeAgentStreamEvent(event.event);
@@ -1309,17 +1298,9 @@ export class Session {
           "agent.session.forward_stream",
         );
 
-        const payload = {
-          agentId: event.agentId,
-          event: serializedEvent,
-          timestamp: new Date().toISOString(),
-          ...(typeof event.seq === "number" ? { seq: event.seq } : {}),
-          ...(typeof event.epoch === "string" ? { epoch: event.epoch } : {}),
-        } as const;
-
         this.emit({
           type: "agent_stream",
-          payload,
+          payload: this.buildAgentStreamPayload(event, serializedEvent),
         });
 
         if (event.event.type === "permission_requested") {
@@ -1347,6 +1328,34 @@ export class Session {
     );
   }
 
+  private shouldSkipAgentStreamForward(agentId: string): boolean {
+    const activity = this.clientActivity;
+    if (activity?.deviceType !== "mobile") {
+      return false;
+    }
+    if (!activity.focusedAgentId || activity.focusedAgentId !== agentId) {
+      return true;
+    }
+    if (activity.appVisible) {
+      return false;
+    }
+    const hiddenForMs = Date.now() - activity.appVisibilityChangedAt.getTime();
+    return hiddenForMs >= this.MOBILE_BACKGROUND_STREAM_GRACE_MS;
+  }
+
+  private buildAgentStreamPayload(
+    event: Extract<AgentManagerEvent, { type: "agent_stream" }>,
+    serializedEvent: Extract<SessionOutboundMessage, { type: "agent_stream" }>["payload"]["event"],
+  ): Extract<SessionOutboundMessage, { type: "agent_stream" }>["payload"] {
+    return {
+      agentId: event.agentId,
+      event: serializedEvent,
+      timestamp: event.timestamp ?? new Date().toISOString(),
+      ...(typeof event.seq === "number" ? { seq: event.seq } : {}),
+      ...(typeof event.epoch === "string" ? { epoch: event.epoch } : {}),
+    };
+  }
+
   private async buildAgentPayload(agent: ManagedAgent): Promise<AgentSnapshotPayload> {
     const storedRecord = await this.agentStorage.get(agent.id);
     const title = storedRecord?.title ?? storedRecord?.config?.title ?? null;