diff --git a/src/app/(modules)/ticket/[ticketId]/components/TicketClassDetailSkeleton.tsx b/src/app/(modules)/ticket/[ticketId]/components/TicketClassDetailSkeleton.tsx
index 769023b..447d87b 100644
--- a/src/app/(modules)/ticket/[ticketId]/components/TicketClassDetailSkeleton.tsx
+++ b/src/app/(modules)/ticket/[ticketId]/components/TicketClassDetailSkeleton.tsx
@@ -1,74 +1,5 @@
 import { Card, CardContent, CardHeader } from '@/components/ui/card';
 import { Skeleton } from '@/components/ui/skeleton';
-import { Timeline, TimelineItem } from '@/components/ui/timeline';
-
-function TimelineEntrySkeleton({
-  index,
-  isLast,
-}: {
-  index: number;
-  isLast: boolean;
-}) {
-  return (
-    <TimelineItem
-      layout="left"
-      isLast={isLast}
-      opposite={
-        <div className="space-y-2">
-          <Skeleton className="ml-auto h-4 w-16" />
-          <Skeleton className="ml-auto h-3 w-12" />
-        </div>
-      }
-      marker={<Skeleton className="size-4 rounded-full" />}
-    >
-      <div
-        className={
-          index === 0
-            ? 'rounded-lg border border-dashed border-primary/25 bg-primary/5 px-4 py-3.5'
-            : 'rounded-lg border bg-card p-4'
-        }
-      >
-        {index === 0 ? <Skeleton className="h-5 w-28 rounded-lg" /> : null}
-        <Skeleton className={index === 0 ? 'mt-3 h-4 w-44' : 'h-4 w-44'} />
-        {index === 0 ? (
-          <Skeleton className="mt-2 h-3 w-full max-w-md" />
-        ) : (
-          <>
-            <div className="mt-3 flex items-center gap-3">
-              <Skeleton className="size-9 rounded-full" />
-              <div className="min-w-0 flex-1 space-y-2">
-                <Skeleton className="h-4 w-36" />
-                <Skeleton className="h-3 w-48 max-w-full" />
-              </div>
-            </div>
-            <Skeleton className="mt-3 h-16 w-full rounded-lg" />
-          </>
-        )}
-      </div>
-    </TimelineItem>
-  );
-}
-
-export function TicketClassContentSkeleton() {
-  return (
-    <div className="space-y-4" aria-label="Loading defect class details">
-      <div className="flex items-center gap-2">
-        <Skeleton className="size-5 rounded-lg" />
-        <Skeleton className="h-5 w-56 max-w-full" />
-      </div>
-
-      <Timeline>
-        {Array.from({ length: 3 }).map((_, index) => (
-          <TimelineEntrySkeleton
-            key={index}
-            index={index}
-            isLast={index === 2}
-          />
-        ))}
-      </Timeline>
-    </div>
-  );
-}
 
 export function TicketClassActionsSkeleton() {
   return (
diff --git a/src/app/(modules)/ticket/[ticketId]/components/TicketHistoryCard.tsx b/src/app/(modules)/ticket/[ticketId]/components/TicketHistoryCard.tsx
index 95037a5..0078ad1 100644
--- a/src/app/(modules)/ticket/[ticketId]/components/TicketHistoryCard.tsx
+++ b/src/app/(modules)/ticket/[ticketId]/components/TicketHistoryCard.tsx
@@ -1,28 +1,56 @@
 'use client';
 
-import { History, MessageSquareText } from 'lucide-react';
+import { History, MessageSquareText, RefreshCw } from 'lucide-react';
 
 import { PersonInfo } from '@/components/person-avatar';
 import { Badge } from '@/components/ui/badge';
+import { Button } from '@/components/ui/button';
 import { Timeline, TimelineItem } from '@/components/ui/timeline';
 import { cn } from '@/lib/utils';
-import type { TicketDetail, TicketHistoryItem, TicketHistorySource } from '@/types';
+import type {
+  TicketTimelineEventType,
+  TicketTimelineItem,
+  TicketTimelineNoteKind,
+  TicketTimelineSource,
+  TicketTimelineUser,
+} from '@/types';
 import { formatTimelineDateTime } from '@/utils/date';
 import { getPersonLabel } from '@/utils/person';
 
+import { useTicketTimelineQuery } from '../../hooks/useTicketQueries';
+import { TicketTimelineSkeleton } from './TicketTimelineSkeleton';
+
 function TimelineDate({ value }: { value: string }) {
   const { date, time } = formatTimelineDateTime(value);
 
   return (
     <time dateTime={value} className="block tabular-nums">
-      <span className="block text-sm font-semibold text-foreground">{date}</span>
+      <span className="block text-sm font-semibold text-foreground">
+        {date}
+      </span>
       <span className="block text-xs text-muted-foreground">{time}</span>
     </time>
   );
 }
 
-function HistoryNote({ item }: { item: TicketHistoryItem }) {
-  const noteText = item.note?.text?.trim();
+function getNoteKindLabel(kind: TicketTimelineNoteKind) {
+  switch (kind) {
+    case 'system_note':
+      return 'System note';
+    case 'repair_note':
+      return 'Repair note';
+    case 'review_comment':
+      return 'Review comment';
+    default:
+      return 'Note';
+  }
+}
+
+function HistoryNote({ item }: { item: TicketTimelineItem }) {
+  const note = item.note;
+  if (!note) return null;
+
+  const noteText = note.text.trim();
   if (!noteText) return null;
 
   return (
@@ -30,7 +58,7 @@ function HistoryNote({ item }: { item: TicketHistoryItem }) {
       <div className="flex items-center gap-1.5 text-xs font-medium text-amber-900 dark:text-amber-200">
         <MessageSquareText className="size-3.5 shrink-0 text-amber-700 dark:text-amber-300" />
         <span>
-          Note by {getPersonLabel(item.note?.author ?? item.actor)}
+          {getNoteKindLabel(note.kind)} by {getPersonLabel(note.author)}
         </span>
       </div>
       <p className="mt-1.5 text-sm leading-relaxed text-amber-950/80 dark:text-amber-100/90">
@@ -40,22 +68,21 @@ function HistoryNote({ item }: { item: TicketHistoryItem }) {
   );
 }
 
-function getSourceLabel(source: TicketHistorySource) {
+function getSourceLabel(source: TicketTimelineSource) {
   return source === 'system' ? 'System Generated' : 'User Action';
 }
 
-function SystemHistoryEntry({ item }: { item: TicketHistoryItem }) {
+function SystemHistoryEntry({ item }: { item: TicketTimelineItem }) {
   const noteText = item.note?.text?.trim();
 
   return (
     <div className="rounded-lg border border-dashed border-primary/25 bg-primary/5 px-4 py-3.5">
-      <Badge
-        
-        className="rounded-lg px-2.5 py-0.5 text-[10px] font-semibold tracking-wider uppercase"
-      >
+      <Badge className="rounded-lg px-2.5 py-0.5 text-[10px] font-semibold tracking-wider uppercase">
         {getSourceLabel(item.source)}
       </Badge>
-      <h3 className="mt-2 text-sm font-semibold text-foreground">{item.title}</h3>
+      <h3 className="mt-2 text-sm font-semibold text-foreground">
+        {item.title}
+      </h3>
       {noteText ? (
         <p className="mt-1 text-sm leading-relaxed text-muted-foreground">
           {noteText}
@@ -65,17 +92,52 @@ function SystemHistoryEntry({ item }: { item: TicketHistoryItem }) {
   );
 }
 
-function UserHistoryEntry({ item }: { item: TicketHistoryItem }) {
+function isSameUser(actor: TicketTimelineUser, target: TicketTimelineUser) {
+  if (actor.user_id !== null && target.user_id !== null) {
+    return actor.user_id === target.user_id;
+  }
+
+  const actorEmail = actor.email?.trim().toLowerCase();
+  const targetEmail = target.email?.trim().toLowerCase();
+  if (actorEmail && targetEmail) return actorEmail === targetEmail;
+
+  return (
+    Boolean(actor.name?.trim()) &&
+    actor.name?.trim().toLowerCase() === target.name?.trim().toLowerCase()
+  );
+}
+
+function getTargetLabel(eventType: TicketTimelineEventType | null) {
+  switch (eventType) {
+    case 'assignment_added':
+      return 'Assigned to';
+    case 'assignment_replaced':
+      return 'Replacement worker';
+    case 'assignment_updated':
+      return 'Assigned worker';
+    case 'assignment_deleted':
+      return 'Removed worker';
+    default:
+      return 'Affected worker';
+  }
+}
+
+function UserHistoryEntry({ item }: { item: TicketTimelineItem }) {
   const noteText = item.note?.text?.trim();
-  const isAssigned = item.event_type === 'assigned';
+  const showTargetUser =
+    item.target_user && !isSameUser(item.actor, item.target_user);
 
   return (
     <div className="rounded-lg border bg-card p-4">
-      <h3 className="mb-3 text-sm font-semibold text-foreground">{item.title}</h3>
+      <h3 className="mb-3 text-sm font-semibold text-foreground">
+        {item.title}
+      </h3>
       <PersonInfo person={item.actor} />
-      {isAssigned && item.target_user ? (
+      {showTargetUser && item.target_user ? (
         <div className="mt-3 space-y-1">
-          <p className="text-xs text-muted-foreground">Assigned to</p>
+          <p className="text-xs text-muted-foreground">
+            {getTargetLabel(item.event_type)}
+          </p>
           <PersonInfo person={item.target_user} />
         </div>
       ) : null}
@@ -84,17 +146,54 @@ function UserHistoryEntry({ item }: { item: TicketHistoryItem }) {
   );
 }
 
-export function TicketHistoryCard({ ticket }: { ticket: TicketDetail }) {
-  const history = ticket.history ?? [];
+function TimelineHeader() {
+  return (
+    <div className="flex items-center gap-2">
+      <History className="size-5 text-primary" />
+      <h2 className="text-base font-semibold">Audit & Lifecycle Timeline</h2>
+    </div>
+  );
+}
+
+export function TicketHistoryCard({ ticketId }: { ticketId: string }) {
+  const timelineQuery = useTicketTimelineQuery(ticketId);
+
+  if (timelineQuery.isLoading) {
+    return <TicketTimelineSkeleton />;
+  }
+
+  const history = timelineQuery.data?.history ?? [];
 
   return (
     <div className="space-y-4">
-      <div className="flex items-center gap-2">
-        <History className="size-5 text-primary" />
-        <h2 className="text-base font-semibold">Audit & Lifecycle Timeline</h2>
-      </div>
+      <TimelineHeader />
 
-      {history.length ? (
+      {timelineQuery.isError ? (
+        <div
+          role="alert"
+          className="rounded-lg border border-dashed border-destructive/40 bg-destructive/5 px-4 py-6 text-center"
+        >
+          <p className="text-sm text-destructive">
+            Failed to load the ticket timeline.
+          </p>
+          <Button
+            type="button"
+            variant="outline"
+            size="sm"
+            className="mt-3"
+            disabled={timelineQuery.isFetching}
+            onClick={() => timelineQuery.refetch()}
+          >
+            <RefreshCw
+              className={cn(
+                'size-4',
+                timelineQuery.isFetching && 'animate-spin',
+              )}
+            />
+            Retry
+          </Button>
+        </div>
+      ) : history.length ? (
         <Timeline>
           {history.map((item, index) => (
             <TimelineItem
diff --git a/src/app/(modules)/ticket/[ticketId]/components/TicketStatusActions.tsx b/src/app/(modules)/ticket/[ticketId]/components/TicketStatusActions.tsx
index a8d691a..b193b01 100644
--- a/src/app/(modules)/ticket/[ticketId]/components/TicketStatusActions.tsx
+++ b/src/app/(modules)/ticket/[ticketId]/components/TicketStatusActions.tsx
@@ -4,8 +4,6 @@ import { PERMISSIONS } from '@/constants/permissions';
 import { PermissionGuard } from '@/guards';
 import type { TicketAssignmentSummary, TicketDetail } from '@/types';
 
-import { AssignedContractorAction } from './actions/AssignedContractorAction';
-import { ClosedTicketAction } from './actions/ClosedTicketAction';
 import { NoTicketAction } from './actions/NoTicketAction';
 import { RequestExtensionAction } from './actions/RequestExtensionAction';
 import { ReviewExtensionRequestAction } from './actions/ReviewExtensionRequestAction';
@@ -36,46 +34,15 @@ function getTicketAction(
           </PermissionGuard>
         }
       >
-        <>
-          {ticket.assignment_status === 'assigned' ? (
-            <AssignedContractorAction ticket={ticket} />
-          ) : null}
-          <ReviewExtensionRequestAction
-            ticket={ticket}
-            assignmentId={assignment.id}
-          />
-        </>
+        <ReviewExtensionRequestAction
+          ticket={ticket}
+          assignmentId={assignment.id}
+        />
       </PermissionGuard>
     );
   }
 
-  if (ticket.assignment_status === 'unassigned') {
-    return null;
-  }
-
-  if (ticket.assignment_status === 'assigned') {
-    return (
-      <PermissionGuard
-        permissions={PERMISSIONS.TICKET.ASSIGN}
-        fallback={<NoTicketAction />}
-      >
-        <AssignedContractorAction ticket={ticket} />
-      </PermissionGuard>
-    );
-  }
-
-  if (ticket.assignment_status === 'under_review') {
-    return null;
-  }
-
-  if (
-    ticket.assignment_status === 'approved' ||
-    ticket.assignment_status === 'rejected'
-  ) {
-    return <ClosedTicketAction ticket={ticket} />;
-  }
-
-  return <NoTicketAction />;
+  return null;
 }
 
 export function TicketStatusActions({
diff --git a/src/app/(modules)/ticket/[ticketId]/components/TicketTimelineSkeleton.tsx b/src/app/(modules)/ticket/[ticketId]/components/TicketTimelineSkeleton.tsx
new file mode 100644
index 0000000..c4f04e9
--- /dev/null
+++ b/src/app/(modules)/ticket/[ticketId]/components/TicketTimelineSkeleton.tsx
@@ -0,0 +1,70 @@
+import { Skeleton } from '@/components/ui/skeleton';
+import { Timeline, TimelineItem } from '@/components/ui/timeline';
+
+function TimelineEntrySkeleton({
+  index,
+  isLast,
+}: {
+  index: number;
+  isLast: boolean;
+}) {
+  return (
+    <TimelineItem
+      layout="left"
+      isLast={isLast}
+      opposite={
+        <div className="space-y-2">
+          <Skeleton className="ml-auto h-4 w-16" />
+          <Skeleton className="ml-auto h-3 w-12" />
+        </div>
+      }
+      marker={<Skeleton className="size-4 rounded-full" />}
+    >
+      <div
+        className={
+          index === 0
+            ? 'rounded-lg border border-dashed border-primary/25 bg-primary/5 px-4 py-3.5'
+            : 'rounded-lg border bg-card p-4'
+        }
+      >
+        {index === 0 ? <Skeleton className="h-5 w-28 rounded-lg" /> : null}
+        <Skeleton className={index === 0 ? 'mt-3 h-4 w-44' : 'h-4 w-44'} />
+        {index === 0 ? (
+          <Skeleton className="mt-2 h-3 w-full max-w-md" />
+        ) : (
+          <>
+            <div className="mt-3 flex items-center gap-3">
+              <Skeleton className="size-9 rounded-full" />
+              <div className="min-w-0 flex-1 space-y-2">
+                <Skeleton className="h-4 w-36" />
+                <Skeleton className="h-3 w-48 max-w-full" />
+              </div>
+            </div>
+            <Skeleton className="mt-3 h-16 w-full rounded-lg" />
+          </>
+        )}
+      </div>
+    </TimelineItem>
+  );
+}
+
+export function TicketTimelineSkeleton() {
+  return (
+    <div className="space-y-4" aria-label="Loading ticket timeline">
+      <div className="flex items-center gap-2">
+        <Skeleton className="size-5 rounded-lg" />
+        <Skeleton className="h-5 w-56 max-w-full" />
+      </div>
+
+      <Timeline>
+        {Array.from({ length: 3 }).map((_, index) => (
+          <TimelineEntrySkeleton
+            key={index}
+            index={index}
+            isLast={index === 2}
+          />
+        ))}
+      </Timeline>
+    </div>
+  );
+}
diff --git a/src/app/(modules)/ticket/[ticketId]/components/actions/ClosedTicketAction.tsx b/src/app/(modules)/ticket/[ticketId]/components/actions/ClosedTicketAction.tsx
index f99bebc..61ec5dd 100644
--- a/src/app/(modules)/ticket/[ticketId]/components/actions/ClosedTicketAction.tsx
+++ b/src/app/(modules)/ticket/[ticketId]/components/actions/ClosedTicketAction.tsx
@@ -16,21 +16,6 @@ import { cn } from '@/lib/utils';
 import type { TicketDetail } from '@/types';
 import { formatDateOnly } from '@/utils/date';
 
-function getClosedAt(ticket: TicketDetail) {
-  const approvedEntry = [...(ticket.history ?? [])]
-    .reverse()
-    .find(
-      (item) =>
-        item.event_type === 'repair_approved' ||
-        item.to_class_status === 'approved',
-    );
-  return (
-    approvedEntry?.created_at ??
-    ticket.reviewer?.reviewed_at ??
-    ticket.timestamps.updated_at
-  );
-}
-
 function MetaField({
   label,
   value,
@@ -79,13 +64,15 @@ function FinalCommentsPanel({
 
 export function ClosedTicketAction({ ticket }: { ticket: TicketDetail }) {
   const reviewer = ticket.reviewer;
-  const reviewedAt = reviewer?.reviewed_at ?? getClosedAt(ticket);
+  const reviewedAt = reviewer?.reviewed_at ?? ticket.timestamps.updated_at;
 
   return (
     <Card>
       <CardHeader>
         <CardTitle className="text-lg">Resolution Details</CardTitle>
-        <CardDescription>Review record for {ticket.ticket_name}</CardDescription>
+        <CardDescription>
+          Review record for {ticket.ticket_name}
+        </CardDescription>
       </CardHeader>
 
       <CardContent className="space-y-5">
@@ -95,10 +82,7 @@ export function ClosedTicketAction({ ticket }: { ticket: TicketDetail }) {
             value={<PersonInfo person={reviewer} size="lg" />}
           />
 
-          <MetaField
-            label="Reviewed Date"
-            value={formatDateOnly(reviewedAt)}
-          />
+          <MetaField label="Reviewed Date" value={formatDateOnly(reviewedAt)} />
         </div>
 
         <div className="space-y-2">
diff --git a/src/app/(modules)/ticket/[ticketId]/components/actions/ReviewExtensionRequestAction.tsx b/src/app/(modules)/ticket/[ticketId]/components/actions/ReviewExtensionRequestAction.tsx
index 9da0b5b..e0ae635 100644
--- a/src/app/(modules)/ticket/[ticketId]/components/actions/ReviewExtensionRequestAction.tsx
+++ b/src/app/(modules)/ticket/[ticketId]/components/actions/ReviewExtensionRequestAction.tsx
@@ -10,6 +10,16 @@ import {
   X,
 } from 'lucide-react';
 
+import {
+  AlertDialog,
+  AlertDialogAction,
+  AlertDialogCancel,
+  AlertDialogContent,
+  AlertDialogDescription,
+  AlertDialogFooter,
+  AlertDialogHeader,
+  AlertDialogTitle,
+} from '@/components/ui/alert-dialog';
 import { Button } from '@/components/ui/button';
 import { Label } from '@/components/ui/label';
 import { Textarea } from '@/components/ui/textarea';
@@ -85,9 +95,12 @@ function ExtensionReviewForm({
   request: TicketExtensionRequest;
 }) {
   const [note, setNote] = useState('');
+  const [noteError, setNoteError] = useState<string | null>(null);
   const [selectedAction, setSelectedAction] = useState<
     'approve' | 'reject' | null
   >(null);
+  const [isRejectConfirmationOpen, setIsRejectConfirmationOpen] =
+    useState(false);
   const reviewMutation = useReviewTicketExtensionMutation(
     ticket.id,
     assignmentId,
@@ -96,14 +109,35 @@ function ExtensionReviewForm({
   const extensionDays = getExtensionDays(request);
 
   const submitDecision = async (action: 'approve' | 'reject') => {
+    const trimmedNote = note.trim();
+
+    if (action === 'reject' && !trimmedNote) {
+      setNoteError('Manager comments are required to reject this request.');
+      setIsRejectConfirmationOpen(false);
+      return;
+    }
+
     setSelectedAction(action);
     try {
-      await reviewMutation.mutateAsync({ action, note: note.trim() });
+      await reviewMutation.mutateAsync({
+        action,
+        ...(trimmedNote ? { note: trimmedNote } : {}),
+      });
     } finally {
       setSelectedAction(null);
     }
   };
 
+  const handleRejectRequest = () => {
+    if (!note.trim()) {
+      setNoteError('Manager comments are required to reject this request.');
+      return;
+    }
+
+    setNoteError(null);
+    setIsRejectConfirmationOpen(true);
+  };
+
   return (
     <TicketActionCard icon={CalendarClock} title="Extension Request Details">
       <div className="space-y-4">
@@ -142,25 +176,41 @@ function ExtensionReviewForm({
         </section>
 
         <div className="space-y-2">
-          <Label htmlFor="extension-manager-note">
-            Add Manager Comments{' '}
-            <span className="text-muted-foreground">(Optional)</span>
-          </Label>
+          <div className="space-y-0.5">
+            <Label htmlFor="extension-manager-note">Add Manager Comments</Label>
+            <p className="text-xs text-muted-foreground">
+              Required for rejection and optional for approval.
+            </p>
+          </div>
           <div className="relative">
             <Textarea
               id="extension-manager-note"
               value={note}
-              onChange={(event) =>
-                setNote(event.target.value.slice(0, MAX_NOTE_LENGTH))
-              }
+              onChange={(event) => {
+                const nextNote = event.target.value.slice(0, MAX_NOTE_LENGTH);
+                setNote(nextNote);
+                if (nextNote.trim()) setNoteError(null);
+              }}
               placeholder="Add a note explaining your decision..."
               disabled={reviewMutation.isPending}
+              aria-invalid={Boolean(noteError)}
+              aria-describedby={
+                noteError ? 'extension-manager-note-error' : undefined
+              }
               className="min-h-24 resize-none pb-8"
             />
             <span className="pointer-events-none absolute right-3 bottom-2 text-xs text-muted-foreground">
               {note.length} / {MAX_NOTE_LENGTH}
             </span>
           </div>
+          {noteError ? (
+            <p
+              id="extension-manager-note-error"
+              className="text-xs text-destructive"
+            >
+              {noteError}
+            </p>
+          ) : null}
         </div>
 
         <div className="grid grid-cols-2 gap-3">
@@ -169,7 +219,7 @@ function ExtensionReviewForm({
             variant="outline"
             className="border-destructive/40 text-destructive hover:bg-destructive/5 hover:text-destructive"
             disabled={reviewMutation.isPending}
-            onClick={() => submitDecision('reject')}
+            onClick={handleRejectRequest}
           >
             {selectedAction === 'reject' ? (
               <Loader2 className="animate-spin" />
@@ -191,6 +241,33 @@ function ExtensionReviewForm({
             Approve Extension
           </Button>
         </div>
+
+        <AlertDialog
+          open={isRejectConfirmationOpen}
+          onOpenChange={setIsRejectConfirmationOpen}
+        >
+          <AlertDialogContent>
+            <AlertDialogHeader>
+              <AlertDialogTitle>Reject extension request?</AlertDialogTitle>
+              <AlertDialogDescription>
+                Are you sure you want to reject this extension request? This
+                decision cannot be undone.
+              </AlertDialogDescription>
+            </AlertDialogHeader>
+            <AlertDialogFooter>
+              <AlertDialogCancel disabled={reviewMutation.isPending}>
+                No
+              </AlertDialogCancel>
+              <AlertDialogAction
+                variant="destructive"
+                disabled={reviewMutation.isPending}
+                onClick={() => submitDecision('reject')}
+              >
+                Yes
+              </AlertDialogAction>
+            </AlertDialogFooter>
+          </AlertDialogContent>
+        </AlertDialog>
       </div>
     </TicketActionCard>
   );
diff --git a/src/app/(modules)/ticket/[ticketId]/page.tsx b/src/app/(modules)/ticket/[ticketId]/page.tsx
index 4c569ec..c78beed 100644
--- a/src/app/(modules)/ticket/[ticketId]/page.tsx
+++ b/src/app/(modules)/ticket/[ticketId]/page.tsx
@@ -12,12 +12,11 @@ import {
   TicketOverviewHeaderSkeleton,
 } from './components/TicketOverviewSkeleton';
 import { TicketClassActionsSkeleton } from './components/TicketClassDetailSkeleton';
-
-// import { TicketHistoryCard } from './components/TicketHistoryCard';
 import { TicketAssignmentsCard } from './components/TicketAssignmentsCard';
 import { TicketOverviewCard } from './components/TicketOverviewCard';
 import { TicketStatusActions } from './components/TicketStatusActions';
 import { TicketDefectClassTabs } from './components/TicketDefectClassTabs';
+import { TicketHistoryCard } from './components/TicketHistoryCard';
 import { useTicketDetailEvents } from '../hooks/useTicketDetailEvents';
 import {
   useTicketAssignmentsQuery,
@@ -101,13 +100,7 @@ export default function TicketDetailPage() {
               assignmentId={activeAssignment.id}
             />
           ) : null}
-          {/* Audit & Lifecycle Timeline is temporarily hidden.
-          {activeAssignment && isClassDetailLoading ? (
-            <TicketClassContentSkeleton />
-          ) : null}
-          {activeAssignment && !isClassDetailLoading && classDetail ? (
-            <TicketHistoryCard ticket={classDetail} />
-          ) : null} */}
+          <TicketHistoryCard ticketId={ticketId} />
         </div>
 
         <div className="min-w-0 space-y-3 self-start xl:min-h-0 xl:self-stretch xl:overflow-y-auto xl:overscroll-contain xl:pr-2">
diff --git a/src/app/(modules)/ticket/hooks/useTicketDetailEvents.ts b/src/app/(modules)/ticket/hooks/useTicketDetailEvents.ts
index 823c023..e7ba85c 100644
--- a/src/app/(modules)/ticket/hooks/useTicketDetailEvents.ts
+++ b/src/app/(modules)/ticket/hooks/useTicketDetailEvents.ts
@@ -35,6 +35,9 @@ export function useTicketDetailEvents(
     queryClient.refetchQueries({
       queryKey: ticketKeys.assignments(ticketId),
     });
+    queryClient.refetchQueries({
+      queryKey: ticketKeys.timeline(ticketId),
+    });
     if (defectClassRef.current) {
       queryClient.refetchQueries({
         queryKey: ticketKeys.classDetail(ticketId, defectClassRef.current),
diff --git a/src/app/(modules)/ticket/hooks/useTicketQueries.ts b/src/app/(modules)/ticket/hooks/useTicketQueries.ts
index 015f9f8..8fe2cdc 100644
--- a/src/app/(modules)/ticket/hooks/useTicketQueries.ts
+++ b/src/app/(modules)/ticket/hooks/useTicketQueries.ts
@@ -70,6 +70,14 @@ export function useTicketOverviewQuery(ticketId: string | undefined) {
   });
 }
 
+export function useTicketTimelineQuery(ticketId: string | undefined) {
+  return useQuery({
+    queryKey: ticketKeys.timeline(ticketId ?? ''),
+    queryFn: () => ticketService.getTicketTimeline(ticketId as string),
+    enabled: Boolean(ticketId),
+  });
+}
+
 export function useTicketClassDetailQuery(
   ticketId: string | undefined,
   defectClass: string | undefined,
@@ -296,6 +304,9 @@ export function useReviewDetectionRepairProofMutation({
         queryClient.invalidateQueries({
           queryKey: ticketKeys.overview(ticketId),
         }),
+        queryClient.invalidateQueries({
+          queryKey: ticketKeys.timeline(ticketId),
+        }),
         queryClient.invalidateQueries({ queryKey: ticketKeys.lists() }),
       ]);
     },
@@ -326,19 +337,6 @@ export function useAssignableTicketUsersQuery(enabled: boolean) {
   });
 }
 
-function mergeTicketDetailResponse(
-  current: TicketDetail | undefined,
-  next: TicketDetail,
-) {
-  if (!current) return next;
-
-  return {
-    ...current,
-    ...next,
-    history: next.history ?? current.history,
-  };
-}
-
 export function useAssignTicketMutation(ticketId: string, videoId?: string) {
   const queryClient = useQueryClient();
 
@@ -351,6 +349,9 @@ export function useAssignTicketMutation(ticketId: string, videoId?: string) {
         queryClient.invalidateQueries({
           queryKey: ticketKeys.overview(ticketId),
         }),
+        queryClient.invalidateQueries({
+          queryKey: ticketKeys.timeline(ticketId),
+        }),
         queryClient.invalidateQueries({ queryKey: ticketKeys.lists() }),
         ...(videoId
           ? [
@@ -397,6 +398,9 @@ export function useRequestTicketExtensionMutation(
       queryClient.invalidateQueries({
         queryKey: ticketKeys.assignments(ticketId),
       });
+      queryClient.invalidateQueries({
+        queryKey: ticketKeys.timeline(ticketId),
+      });
       queryClient.invalidateQueries({ queryKey: ticketKeys.lists() });
     },
     onError: () => toast.error('Failed to request an extension'),
@@ -427,6 +431,9 @@ export function useReviewTicketExtensionMutation(
       queryClient.invalidateQueries({
         queryKey: ticketKeys.assignments(ticketId),
       });
+      queryClient.invalidateQueries({
+        queryKey: ticketKeys.timeline(ticketId),
+      });
       queryClient.invalidateQueries({ queryKey: ticketKeys.lists() });
     },
     onError: () => toast.error('Failed to review extension request'),
@@ -442,8 +449,11 @@ export function useCloseTicketMutation(ticketId: string) {
       toast.success('Ticket closed');
       queryClient.setQueryData<TicketDetail>(
         ticketKeys.classDetail(ticketId, payload.defect_class),
-        (current) => mergeTicketDetailResponse(current, ticket),
+        ticket,
       );
+      queryClient.invalidateQueries({
+        queryKey: ticketKeys.timeline(ticketId),
+      });
       queryClient.invalidateQueries({ queryKey: ticketKeys.lists() });
     },
     onError: () => toast.error('Failed to close ticket'),
diff --git a/src/app/(modules)/ticket/queries/ticketKeys.ts b/src/app/(modules)/ticket/queries/ticketKeys.ts
index cad008c..79de18c 100644
--- a/src/app/(modules)/ticket/queries/ticketKeys.ts
+++ b/src/app/(modules)/ticket/queries/ticketKeys.ts
@@ -11,6 +11,8 @@ export const ticketKeys = {
   details: () => [...ticketKeys.all, 'detail'] as const,
   overview: (ticketId: string) =>
     [...ticketKeys.details(), ticketId, 'overview'] as const,
+  timeline: (ticketId: string) =>
+    [...ticketKeys.details(), ticketId, 'timeline'] as const,
   classDetail: (ticketId: string, defectClass: string) =>
     [...ticketKeys.details(), ticketId, 'class', defectClass] as const,
   classDetectionLists: (videoId: string) =>
diff --git a/src/constants/apiRoutes.ts b/src/constants/apiRoutes.ts
index 74bd155..641138a 100644
--- a/src/constants/apiRoutes.ts
+++ b/src/constants/apiRoutes.ts
@@ -65,6 +65,7 @@ export const API_ROUTES = {
   TICKETS: {
     BASE: '/biz/api/v1/tickets',
     DETAIL: (id: string) => `/biz/api/v1/tickets/${id}`,
+    TIMELINE: (id: string) => `/biz/api/v1/tickets/${id}/timeline`,
     CLASS_DETAIL: (id: string, defectClass: string) =>
       `/biz/api/v1/tickets/${id}/class-detail?defect_class=${defectClass}`,
     DEFECT_CLASSES: (id: string) => `/biz/api/v1/tickets/${id}/defect-classes`,
diff --git a/src/services/api/ticket.service.ts b/src/services/api/ticket.service.ts
index 4daad34..5d20ed3 100644
--- a/src/services/api/ticket.service.ts
+++ b/src/services/api/ticket.service.ts
@@ -16,6 +16,7 @@ import type {
   TicketDefectClassesResponse,
   TicketListParams,
   TicketListResponse,
+  TicketTimelineResponse,
 } from '@/types';
 
 type TicketAssignmentsApiResponse =
@@ -52,6 +53,15 @@ export const ticketService = {
     return response.data;
   },
 
+  getTicketTimeline: async (
+    ticketId: string,
+  ): Promise<TicketTimelineResponse> => {
+    const response = await axiosClient.get<TicketTimelineResponse>(
+      API_ROUTES.TICKETS.TIMELINE(ticketId),
+    );
+    return response.data;
+  },
+
   getTicketClassDetail: async (
     ticketId: string,
     defectClass: string,
diff --git a/src/types/ticket/actions.ts b/src/types/ticket/actions.ts
index b05c72a..940be53 100644
--- a/src/types/ticket/actions.ts
+++ b/src/types/ticket/actions.ts
@@ -46,7 +46,7 @@ export interface RequestTicketExtensionPayload {
 
 export interface ReviewTicketExtensionPayload {
   action: 'approve' | 'reject';
-  note: string;
+  note?: string;
 }
 
 export interface TicketExtensionRequestActor {
diff --git a/src/types/ticket/detail.ts b/src/types/ticket/detail.ts
index 1c14d6b..a15219f 100644
--- a/src/types/ticket/detail.ts
+++ b/src/types/ticket/detail.ts
@@ -9,29 +9,6 @@ export interface TicketActor {
   avatar_url?: string | null;
 }
 
-export type TicketHistorySource = 'system' | 'user';
-
-export interface TicketHistoryNote {
-  kind: string;
-  author: TicketActor | null;
-  text: string;
-}
-
-export interface TicketHistoryItem {
-  id: number;
-  event_type: string;
-  title: string;
-  source: TicketHistorySource;
-  assignment_id: number | null;
-  defect_class: string | null;
-  from_class_status: TicketDefectClassTicketStatus | null;
-  to_class_status: TicketDefectClassTicketStatus | null;
-  actor: TicketActor | null;
-  target_user: TicketActor | null;
-  note: TicketHistoryNote | null;
-  created_at: string;
-}
-
 export interface TicketStatusMetadata {
   reason: string | null;
   label: string | null;
@@ -180,5 +157,4 @@ export interface TicketDetail {
   ai_result: TicketAiResult | null;
   tenant: TicketTenant | null;
   timestamps: TicketTimestamps;
-  history: TicketHistoryItem[];
 }
diff --git a/src/types/ticket/index.ts b/src/types/ticket/index.ts
index 4f98cfd..ebbaa7c 100644
--- a/src/types/ticket/index.ts
+++ b/src/types/ticket/index.ts
@@ -4,3 +4,4 @@ export * from './detail';
 export * from './actions';
 export * from './defect-class';
 export * from './events';
+export * from './timeline';
diff --git a/src/types/ticket/timeline.ts b/src/types/ticket/timeline.ts
new file mode 100644
index 0000000..a18c92f
--- /dev/null
+++ b/src/types/ticket/timeline.ts
@@ -0,0 +1,60 @@
+export type UTCDateTimeString = string;
+
+export type TicketTimelineSource = 'system' | 'user';
+
+export type TicketTimelineNoteKind =
+  | 'system_note'
+  | 'user_note'
+  | 'repair_note'
+  | 'review_comment';
+
+export type TicketTimelineEventType =
+  | 'ai_detected'
+  | 'ticket_created'
+  | 'ticket_fully_assigned'
+  | 'ticket_completed'
+  | 'ticket_closed'
+  | 'assignment_added'
+  | 'assignment_replaced'
+  | 'assignment_updated'
+  | 'assignment_deleted'
+  | 'repair_started'
+  | 'repair_submitted'
+  | 'assignment_approve'
+  | 'assignment_reject'
+  | 'extension_requested'
+  | 'extension_approved'
+  | 'extension_rejected'
+  | 'extension_cancelled'
+  | 'lot_submitted_for_review'
+  | 'lot_resubmitted_for_review'
+  | 'lot_returned_for_correction'
+  | 'lot_approved';
+
+export interface TicketTimelineUser {
+  user_id: number | null;
+  name: string | null;
+  email: string | null;
+}
+
+export interface TicketTimelineNote {
+  kind: TicketTimelineNoteKind;
+  author: TicketTimelineUser;
+  text: string;
+}
+
+export interface TicketTimelineItem {
+  id: number;
+  event_type: TicketTimelineEventType | null;
+  title: string;
+  source: TicketTimelineSource;
+  assignment_id: number | null;
+  actor: TicketTimelineUser;
+  target_user: TicketTimelineUser | null;
+  note: TicketTimelineNote | null;
+  created_at: UTCDateTimeString;
+}
+
+export interface TicketTimelineResponse {
+  history: TicketTimelineItem[];
+}