diff --git a/apps/web/src/components/chat/MessagesTimeline.test.tsx b/apps/web/src/components/chat/MessagesTimeline.test.tsx
index 67060a28d647..ccb51900135b 100644
--- a/apps/web/src/components/chat/MessagesTimeline.test.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.test.tsx
@@ -4,6 +4,7 @@ import { createRef, type ReactNode, type Ref } from "react";
 import { renderToStaticMarkup } from "react-dom/server";
 import { beforeAll, describe, expect, it, vi } from "vite-plus/test";
 import type { LegendListRef } from "@legendapp/list/react";
+import { formatDayAwareTimestamp } from "../../timestampFormat";
 
 vi.mock("@legendapp/list/react", async () => {
   const legendListTestId = "legend-list";
@@ -1209,6 +1210,9 @@ describe("MessagesTimeline", () => {
 
     expect(markup).toContain("Running pnpm");
     expect(markup).toContain("live-activity-focus");
+    // The live row is transient (it becomes a collapsed group when the turn
+    // settles), so it intentionally carries no timestamp.
+    expect(markup).not.toContain(formatDayAwareTimestamp(MESSAGE_CREATED_AT, "locale"));
   });
 
   it("scopes a live row failure to the tool named by the row", () => {
@@ -1453,4 +1457,119 @@ describe("MessagesTimeline", () => {
     expect(markup).toContain("lucide-x");
     expect(markup).toContain("text-destructive");
   });
+
+  it("shows a hover timestamp on collapsed tool group rows", () => {
+    const createdAt = "2026-03-17T19:12:28.000Z";
+    const markup = renderToStaticMarkup(
+      <MessagesTimeline
+        {...buildProps()}
+        timelineEntries={[
+          {
+            id: "entry-1",
+            kind: "work",
+            createdAt,
+            entry: {
+              id: "work-1",
+              createdAt,
+              label: "Ran command",
+              tone: "tool",
+              command: "pnpm test",
+            },
+          },
+        ]}
+      />,
+    );
+
+    expect(markup).toContain("Ran 1 command");
+    expect(markup).toContain("group/timeline-row");
+    // The timestamp must be hidden until the row is hovered or focused, so
+    // the assertions pin the reveal itself, not just the text.
+    expect(markup).toContain("opacity-0");
+    expect(markup).toContain("group-hover/timeline-row:opacity-100");
+    expect(markup).toContain("group-focus-within/timeline-row:opacity-100");
+    expect(markup).toContain(formatDayAwareTimestamp(createdAt, "locale"));
+  });
+
+  it("shows a hover timestamp on non-tool activity summaries", () => {
+    const createdAt = "2026-03-17T19:12:28.000Z";
+    const markup = renderToStaticMarkup(
+      <MessagesTimeline
+        {...buildProps()}
+        timelineEntries={[
+          {
+            id: "entry-1",
+            kind: "work",
+            createdAt,
+            entry: {
+              id: "work-1",
+              createdAt,
+              label: "Context compacted",
+              tone: "info",
+            },
+          },
+        ]}
+      />,
+    );
+
+    expect(markup).toContain("Context compacted");
+    expect(markup).toContain("group/timeline-row");
+    expect(markup).toContain("group-hover/timeline-row:opacity-100");
+    expect(markup).toContain("group-focus-within/timeline-row:opacity-100");
+    // The unified activity-summary button is already the keyboard path.
+    expect(markup).toContain('aria-expanded="false"');
+    expect(markup).toContain(formatDayAwareTimestamp(createdAt, "locale"));
+  });
+
+  it("shows a hover timestamp on the worked-for turn fold", () => {
+    const turnId = TurnId.make("turn-folded");
+    const workCreatedAt = "2026-03-17T19:12:28.000Z";
+    const assistantUpdatedAt = "2026-03-17T19:14:30.000Z";
+    const markup = renderToStaticMarkup(
+      <MessagesTimeline
+        {...buildProps()}
+        latestTurn={{
+          turnId,
+          state: "completed",
+          startedAt: workCreatedAt,
+          completedAt: assistantUpdatedAt,
+        }}
+        timelineEntries={[
+          {
+            id: "entry-work",
+            kind: "work",
+            createdAt: workCreatedAt,
+            entry: {
+              id: "work-1",
+              createdAt: workCreatedAt,
+              turnId,
+              label: "Ran command",
+              tone: "tool",
+              command: "pnpm test",
+            },
+          },
+          {
+            id: "entry-assistant",
+            kind: "message",
+            createdAt: assistantUpdatedAt,
+            message: {
+              id: MessageId.make("message-folded"),
+              role: "assistant",
+              text: "Done.",
+              turnId,
+              createdAt: assistantUpdatedAt,
+              updatedAt: assistantUpdatedAt,
+              streaming: false,
+            },
+          },
+        ]}
+      />,
+    );
+
+    // The work entry folds behind the turn fold, so the fold row is the only
+    // place the work entry's start time can render from.
+    expect(markup).toContain("Worked for");
+    expect(markup).toContain(formatDayAwareTimestamp(workCreatedAt, "locale"));
+    // The assistant metadata row keeps its own (later) timestamp.
+    expect(markup).toContain(formatDayAwareTimestamp(assistantUpdatedAt, "locale"));
+  });
 });
diff --git a/apps/web/src/components/chat/MessagesTimeline.tsx b/apps/web/src/components/chat/MessagesTimeline.tsx
index d8c88c088648..b703b2f93bd6 100644
--- a/apps/web/src/components/chat/MessagesTimeline.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.tsx
@@ -1167,6 +1167,40 @@ function RevertUserMessageButton({ messageId }: { messageId: MessageId }) {
   );
 }
 
+/**
+ * Hover-revealed wall-clock time with a full-date tooltip — the same metadata
+ * presentation as message rows, for work entries and turn folds. The parent
+ * carries the `group/timeline-row` class that drives the reveal; keyboard
+ * focus anywhere in that parent reveals it too, since the span itself is not
+ * focusable. Rows without any other focusable element pass
+ * `keyboardReachable` so the span becomes the tab stop and tooltip target.
+ */
+function TimelineRowTimestamp({
+  createdAt,
+  timestampFormat,
+  keyboardReachable = false,
+}: {
+  createdAt: string;
+  timestampFormat: TimestampFormat;
+  keyboardReachable?: boolean;
+}) {
+  return (
+    <Tooltip>
+      <TooltipTrigger
+        render={
+          <span
+            className="me-1 shrink-0 rounded-md text-muted-foreground text-xs tabular-nums opacity-0 transition-opacity duration-200 group-hover/timeline-row:opacity-100 group-focus-within/timeline-row:opacity-100 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring/70"
+            {...(keyboardReachable ? { tabIndex: 0 } : {})}
+          />
+        }
+      >
+        {formatDayAwareTimestamp(createdAt, timestampFormat)}
+      </TooltipTrigger>
+      <TooltipPopup>{formatChatTimestampTooltip(createdAt, timestampFormat)}</TooltipPopup>
+    </Tooltip>
+  );
+}
+
 function TurnFoldTimelineRow({ row }: { row: Extract<TimelineRow, { kind: "turn-fold" }> }) {
   const ctx = use(TimelineRowCtx);
   const Icon = row.expanded ? ChevronDownIcon : ChevronRightIcon;
@@ -1178,9 +1212,10 @@ function TurnFoldTimelineRow({ row }: { row: Extract<TimelineRow, { kind: "turn-
         aria-expanded={row.expanded}
         data-scroll-anchor-ignore
         onClick={() => ctx.onToggleTurnFold(row.turnId)}
-        className="flex cursor-pointer select-none items-center gap-1 rounded-md px-1 text-sm leading-relaxed text-muted-foreground tabular-nums transition-colors hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring/70"
+        className="group/timeline-row flex cursor-pointer select-none items-center gap-1 rounded-md px-1 text-sm leading-relaxed text-muted-foreground tabular-nums transition-colors hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring/70"
       >
         <span>{row.label}</span>
+        <TimelineRowTimestamp createdAt={row.createdAt} timestampFormat={ctx.timestampFormat} />
         <Icon className="size-3.5" />
       </button>
     </div>
@@ -1381,7 +1416,7 @@ const WorkGroupSection = memo(function WorkGroupSection({
   groupedEntries: Extract<MessagesTimelineRow, { kind: "work" }>["groupedEntries"];
   isExpandedToolGroupEntry: boolean;
 }) {
-  const { workspaceRoot } = use(TimelineRowCtx);
+  const { timestampFormat, workspaceRoot } = use(TimelineRowCtx);
   const nonEmptyEntries = useMemo(
     () =>
       groupedEntries.filter((entry) => workEntryIsVisibleInGroup(entry, isExpandedToolGroupEntry)),
@@ -1401,6 +1436,7 @@ const WorkGroupSection = memo(function WorkGroupSection({
           <SimpleWorkEntryRow
             key={workEntry.id}
             workEntry={workEntry}
+            timestampFormat={timestampFormat}
             workspaceRoot={workspaceRoot}
             isExpandedToolGroupEntry={isExpandedToolGroupEntry}
           />
@@ -1539,7 +1575,7 @@ function WorkGroupToggleTimelineRow({
   return (
     <button
       type="button"
-      className="group/tool-group flex min-h-6 w-full cursor-pointer items-center gap-1.5 rounded-md px-0.5 py-0.5 text-left text-sm leading-relaxed transition-colors duration-150 hover:bg-accent/20 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring/70"
+      className="group/tool-group group/timeline-row flex min-h-6 w-full cursor-pointer items-center gap-1.5 rounded-md px-0.5 py-0.5 text-left text-sm leading-relaxed transition-colors duration-150 hover:bg-accent/20 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring/70"
       aria-label={row.hasFailure ? `${row.summary}, tool call failed` : undefined}
       aria-expanded={row.expanded}
       onClick={() => ctx.onToggleWorkGroup(row.groupId, row.id)}
@@ -1551,6 +1587,7 @@ function WorkGroupToggleTimelineRow({
         />
       </span>
       <span className="min-w-0 flex-1 truncate text-secondary-label">{row.summary}</span>
+      <TimelineRowTimestamp createdAt={row.createdAt} timestampFormat={ctx.timestampFormat} />
     </button>
   );
 }
@@ -2504,10 +2541,11 @@ const AgentSpawnCtaRow = memo(function AgentSpawnCtaRow(props: { workEntry: Time
 
 const SimpleWorkEntryRow = memo(function SimpleWorkEntryRow(props: {
   workEntry: TimelineWorkEntry;
+  timestampFormat: TimestampFormat;
   workspaceRoot: string | undefined;
   isExpandedToolGroupEntry: boolean;
 }) {
-  const { workEntry, workspaceRoot, isExpandedToolGroupEntry } = props;
+  const { workEntry, timestampFormat, workspaceRoot, isExpandedToolGroupEntry } = props;
   // Before any hooks: spawn CTA rows render their own component.
   if (workEntry.agentSpawn) {
     return <AgentSpawnCtaRow workEntry={workEntry} />;
@@ -2515,6 +2553,7 @@ const SimpleWorkEntryRow = memo(function SimpleWorkEntryRow(props: {
   return (
     <PlainWorkEntryRow
       workEntry={workEntry}
+      timestampFormat={timestampFormat}
       workspaceRoot={workspaceRoot}
       isExpandedToolGroupEntry={isExpandedToolGroupEntry}
     />
@@ -2523,10 +2562,11 @@ const SimpleWorkEntryRow = memo(function SimpleWorkEntryRow(props: {
 
 const PlainWorkEntryRow = memo(function PlainWorkEntryRow(props: {
   workEntry: TimelineWorkEntry;
+  timestampFormat: TimestampFormat;
   workspaceRoot: string | undefined;
   isExpandedToolGroupEntry: boolean;
 }) {
-  const { workEntry, workspaceRoot, isExpandedToolGroupEntry } = props;
+  const { workEntry, timestampFormat, workspaceRoot, isExpandedToolGroupEntry } = props;
   const [expanded, setExpanded] = useState(false);
   const iconConfig = workToneIcon(workEntry.tone);
   const showWarningIndicator = workEntry.sourceActivityKind === "runtime.warning";
@@ -2581,7 +2621,7 @@ const PlainWorkEntryRow = memo(function PlainWorkEntryRow(props: {
   return (
     <div
       className={cn(
-        "flex flex-col rounded-md px-0.5 transition-colors",
+        "group/timeline-row flex flex-col rounded-md px-0.5 transition-colors",
         isExpandedToolGroupEntry ? "py-0" : "py-0.5",
         canExpand &&
           "cursor-pointer hover:bg-accent/20 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring/70",
@@ -2606,6 +2646,13 @@ const PlainWorkEntryRow = memo(function PlainWorkEntryRow(props: {
               <span className={cn("min-w-0 flex-1 truncate", headingClass)}>{displayText}</span>
             </p>
           </div>
+          <TimelineRowTimestamp
+            createdAt={workEntry.createdAt}
+            timestampFormat={timestampFormat}
+            // Rows that cannot expand have no other focusable element, so
+            // the timestamp itself becomes the keyboard path to its reveal.
+            keyboardReachable={!canExpand}
+          />
           <span
             className={cn(
               "flex size-4 shrink-0 items-center justify-center",