diff --git a/frontend/components/q&a/AccordionList.tsx b/frontend/components/q&a/AccordionList.tsx
index f066a195..2f7f4893 100644
--- a/frontend/components/q&a/AccordionList.tsx
+++ b/frontend/components/q&a/AccordionList.tsx
@@ -7,7 +7,9 @@ import {
   useEffect,
   useState,
 } from 'react';
+import { Bookmark } from 'lucide-react';
 
+import { Badge } from '@/components/ui/badge';
 import AIWordHelper from '@/components/q&a/AIWordHelper';
 import CodeBlock from '@/components/q&a/CodeBlock';
 import FloatingExplainButton from '@/components/q&a/FloatingExplainButton';
@@ -41,6 +43,44 @@ type QaItemStyle = CSSProperties & {
   '--qa-accent-soft': string;
 };
 
+const QA_VIEWED_STORAGE_KEY = 'devlovers_qa_viewed_questions';
+const QA_BOOKMARK_STORAGE_KEY = 'devlovers_qa_bookmarked_questions';
+
+function readStoredQuestionIds(storageKey: string): Set<string> {
+  if (typeof window === 'undefined') return new Set();
+
+  try {
+    const raw = window.localStorage.getItem(storageKey);
+    if (!raw) return new Set();
+
+    const parsed = JSON.parse(raw);
+    if (!Array.isArray(parsed)) return new Set();
+
+    return new Set(
+      parsed.filter((value): value is string => typeof value === 'string')
+    );
+  } catch {
+    return new Set();
+  }
+}
+
+function writeStoredQuestionIds(storageKey: string, ids: Set<string>) {
+  if (typeof window === 'undefined') return;
+  try {
+    window.localStorage.setItem(storageKey, JSON.stringify([...ids]));
+  } catch {
+    // Ignore storage write failures in restricted environments.
+  }
+}
+
+function getQuestionStorageId(question: QuestionEntry): string {
+  if (question.id !== undefined && question.id !== null) {
+    return String(question.id);
+  }
+
+  return `${question.category}:${question.question}`;
+}
+
 function normalizeCachedTerm(term: string): string {
   return term.toLowerCase().trim();
 }
@@ -327,17 +367,30 @@ export default function AccordionList({ items }: { items: QuestionEntry[] }) {
   const [cachedTerms, setCachedTerms] = useState<Set<string>>(
     () => new Set(getCachedTerms().map(normalizeCachedTerm))
   );
+  const [viewedItems, setViewedItems] = useState<Set<string>>(new Set());
+  const [bookmarkedItems, setBookmarkedItems] = useState<Set<string>>(new Set());
 
   const refreshCachedTerms = useCallback(() => {
     const terms = getCachedTerms().map(normalizeCachedTerm);
     setCachedTerms(new Set(terms));
   }, []);
 
+  useEffect(() => {
+    setViewedItems(readStoredQuestionIds(QA_VIEWED_STORAGE_KEY));
+    setBookmarkedItems(readStoredQuestionIds(QA_BOOKMARK_STORAGE_KEY));
+  }, []);
+
   useEffect(() => {
     const handleStorage = (e: StorageEvent) => {
       if (e.key === CACHE_KEY) {
         refreshCachedTerms();
       }
+      if (e.key === null || e.key === QA_VIEWED_STORAGE_KEY) {
+        setViewedItems(readStoredQuestionIds(QA_VIEWED_STORAGE_KEY));
+      }
+      if (e.key === null || e.key === QA_BOOKMARK_STORAGE_KEY) {
+        setBookmarkedItems(readStoredQuestionIds(QA_BOOKMARK_STORAGE_KEY));
+      }
     };
     window.addEventListener('storage', handleStorage);
     return () => window.removeEventListener('storage', handleStorage);
@@ -393,15 +446,46 @@ export default function AccordionList({ items }: { items: QuestionEntry[] }) {
     }
   }, []);
 
+  const markAsViewed = useCallback((questionId: string) => {
+    setViewedItems(prev => {
+      if (prev.has(questionId)) {
+        return prev;
+      }
+
+      const next = new Set(prev);
+      next.add(questionId);
+      writeStoredQuestionIds(QA_VIEWED_STORAGE_KEY, next);
+      return next;
+    });
+  }, []);
+
+  const toggleBookmark = useCallback((questionId: string) => {
+    setBookmarkedItems(prev => {
+      const next = new Set(prev);
+
+      if (next.has(questionId)) {
+        next.delete(questionId);
+      } else {
+        next.add(questionId);
+      }
+
+      writeStoredQuestionIds(QA_BOOKMARK_STORAGE_KEY, next);
+      return next;
+    });
+  }, []);
+
   return (
     <>
       <Accordion type="single" collapsible className="w-full">
         {items.map((q, idx) => {
           const key = q.id ?? idx;
+          const questionId = getQuestionStorageId(q);
           const accentColor =
             categoryTabStyles[q.category as keyof typeof categoryTabStyles]
               ?.accent ?? '#A1A1AA';
           const animationDelay = `${Math.min(idx, 10) * 60}ms`;
+          const isViewed = viewedItems.has(questionId);
+          const isBookmarked = bookmarkedItems.has(questionId);
           const itemStyle: QaItemStyle = {
             animationDelay,
             animationFillMode: 'both',
@@ -418,8 +502,49 @@ export default function AccordionList({ items }: { items: QuestionEntry[] }) {
               <AccordionTrigger
                 className="px-4 hover:no-underline"
                 onPointerDown={clearSelection}
+                onClick={() => markAsViewed(questionId)}
+                trailing={
+                  isViewed ? (
+                    <button
+                      type="button"
+                      aria-label={isBookmarked ? 'Remove bookmark' : 'Add bookmark'}
+                      aria-pressed={isBookmarked}
+                      className="mr-2 inline-flex h-6 w-6 shrink-0 items-center justify-center rounded-sm text-red-500 transition-colors hover:bg-red-500/10 focus-visible:ring-2 focus-visible:ring-red-500/40 focus-visible:outline-none"
+                      onClick={event => {
+                        event.preventDefault();
+                        event.stopPropagation();
+                        toggleBookmark(questionId);
+                      }}
+                    >
+                      <Bookmark
+                        className="h-4 w-4"
+                        fill={isBookmarked ? 'currentColor' : 'none'}
+                      />
+                    </button>
+                  ) : (
+                    <span
+                      aria-hidden="true"
+                      className="mr-2 inline-flex h-6 w-6 shrink-0"
+                    />
+                  )
+                }
               >
-                {q.question}
+                <span className="flex min-w-0 flex-1 items-center gap-3">
+                  <span className="min-w-0 flex-1 truncate">{q.question}</span>
+                  <span className="flex h-6 w-[82px] shrink-0 items-center justify-end">
+                    <Badge
+                      variant="success"
+                      className={
+                        isViewed
+                          ? 'h-6 gap-1 rounded-full px-2 py-0 text-[11px]'
+                          : 'invisible h-6 gap-1 rounded-full px-2 py-0 text-[11px]'
+                      }
+                    >
+                      <span className="h-1.5 w-1.5 rounded-full bg-emerald-500" />
+                      Viewed
+                    </Badge>
+                  </span>
+                </span>
               </AccordionTrigger>
               <AccordionContent className="px-4">
                 <SelectableText
diff --git a/frontend/components/tests/q&a/accordion-list.test.tsx b/frontend/components/tests/q&a/accordion-list.test.tsx
index a7a3eced..ee58d5eb 100644
--- a/frontend/components/tests/q&a/accordion-list.test.tsx
+++ b/frontend/components/tests/q&a/accordion-list.test.tsx
@@ -3,6 +3,23 @@ import { fireEvent, render, screen } from '@testing-library/react';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
 const getCachedTermsMock = vi.fn();
+const storage = new Map<string, string>();
+
+Object.defineProperty(window, 'localStorage', {
+  value: {
+    getItem: (key: string) => storage.get(key) ?? null,
+    setItem: (key: string, value: string) => {
+      storage.set(key, value);
+    },
+    removeItem: (key: string) => {
+      storage.delete(key);
+    },
+    clear: () => {
+      storage.clear();
+    },
+  },
+  configurable: true,
+});
 
 vi.mock('@/lib/ai/explainCache', () => ({
   getCachedTerms: () => getCachedTermsMock(),
@@ -15,8 +32,24 @@ vi.mock('@/components/ui/accordion', () => ({
   AccordionItem: ({ children }: { children: React.ReactNode }) => (
     <div>{children}</div>
   ),
-  AccordionTrigger: ({ children }: { children: React.ReactNode }) => (
-    <button type="button">{children}</button>
+  AccordionTrigger: ({
+    children,
+    leading,
+    trailing,
+    onClick,
+  }: {
+    children: React.ReactNode;
+    leading?: React.ReactNode;
+    trailing?: React.ReactNode;
+    onClick?: () => void;
+  }) => (
+    <div>
+      {leading}
+      <button type="button" onClick={onClick}>
+        {children}
+      </button>
+      {trailing}
+    </div>
   ),
   AccordionContent: ({ children }: { children: React.ReactNode }) => (
     <div>{children}</div>
@@ -113,6 +146,32 @@ import type { QuestionEntry } from '@/components/q&a/types';
 describe('AccordionList', () => {
   beforeEach(() => {
     getCachedTermsMock.mockReturnValue([]);
+    localStorage.clear();
+  });
+
+  it('uses a stable fallback id when question id is missing', () => {
+    const items: QuestionEntry[] = [
+      {
+        question: 'What is CSS?',
+        category: 'css',
+        answerBlocks: [
+          {
+            type: 'paragraph',
+            children: [{ text: 'CSS styles pages.' }],
+          },
+        ],
+      },
+    ];
+
+    render(<AccordionList items={items} />);
+
+    fireEvent.click(screen.getByText('What is CSS?'));
+
+    expect(
+      JSON.parse(
+        localStorage.getItem('devlovers_qa_viewed_questions') ?? '[]'
+      )
+    ).toContain('css:What is CSS?');
   });
 
   it('renders questions and answer blocks', () => {
@@ -136,6 +195,69 @@ describe('AccordionList', () => {
     expect(screen.getByText('CSS styles pages.')).toBeTruthy();
   });
 
+  it('marks an accordion as viewed after opening it', () => {
+    const items: QuestionEntry[] = [
+      {
+        id: 'q1',
+        question: 'What is CSS?',
+        category: 'css',
+        answerBlocks: [
+          {
+            type: 'paragraph',
+            children: [{ text: 'CSS styles pages.' }],
+          },
+        ],
+      },
+    ];
+
+    render(<AccordionList items={items} />);
+
+    expect(
+      screen.queryByRole('button', { name: 'Add bookmark' })
+    ).toBeNull();
+
+    fireEvent.click(screen.getByText('What is CSS?'));
+
+    expect(
+      screen.getByRole('button', { name: 'Add bookmark' })
+    ).toBeTruthy();
+    expect(
+      JSON.parse(
+        localStorage.getItem('devlovers_qa_viewed_questions') ?? '[]'
+      )
+    ).toContain('q1');
+  });
+
+  it('toggles bookmark state for viewed accordion', () => {
+    const items: QuestionEntry[] = [
+      {
+        id: 'q1',
+        question: 'What is CSS?',
+        category: 'css',
+        answerBlocks: [
+          {
+            type: 'paragraph',
+            children: [{ text: 'CSS styles pages.' }],
+          },
+        ],
+      },
+    ];
+
+    render(<AccordionList items={items} />);
+
+    fireEvent.click(screen.getByText('What is CSS?'));
+    fireEvent.click(screen.getByRole('button', { name: 'Add bookmark' }));
+
+    expect(
+      screen.getByRole('button', { name: 'Remove bookmark' })
+    ).toBeTruthy();
+    expect(
+      JSON.parse(
+        localStorage.getItem('devlovers_qa_bookmarked_questions') ?? '[]'
+      )
+    ).toContain('q1');
+  });
+
   it('opens AI helper from selection', () => {
     const items: QuestionEntry[] = [
       {
diff --git a/frontend/components/ui/accordion.tsx b/frontend/components/ui/accordion.tsx
index b82473f0..7cb92c5a 100644
--- a/frontend/components/ui/accordion.tsx
+++ b/frontend/components/ui/accordion.tsx
@@ -28,14 +28,20 @@ function AccordionItem({
 function AccordionTrigger({
   className,
   children,
+  leading,
+  trailing,
   ...props
-}: React.ComponentProps<typeof AccordionPrimitive.Trigger>) {
+}: React.ComponentProps<typeof AccordionPrimitive.Trigger> & {
+  leading?: React.ReactNode;
+  trailing?: React.ReactNode;
+}) {
   return (
     <AccordionPrimitive.Header className="flex">
+      {leading}
       <AccordionPrimitive.Trigger
         data-slot="accordion-trigger"
         className={cn(
-          'focus-visible:border-ring focus-visible:ring-ring/50 flex flex-1 items-start justify-between gap-4 rounded-md py-4 text-left text-sm font-medium transition-all outline-none hover:underline focus-visible:ring-[3px] disabled:pointer-events-none disabled:opacity-50 [&[data-state=open]>svg]:rotate-180',
+          'focus-visible:border-ring focus-visible:ring-ring/50 flex flex-1 items-center justify-between gap-4 rounded-md py-4 text-left text-sm font-medium transition-all outline-none hover:underline focus-visible:ring-[3px] disabled:pointer-events-none disabled:opacity-50 [&[data-state=open]>svg]:rotate-180',
           className
         )}
         {...props}
@@ -43,9 +49,10 @@ function AccordionTrigger({
         {children}
         <ChevronDownIcon
           aria-hidden="true"
-          className="text-muted-foreground pointer-events-none size-4 shrink-0 translate-y-0.5 transition-transform duration-200"
+          className="text-muted-foreground pointer-events-none size-4 shrink-0 transition-transform duration-200"
         />
       </AccordionPrimitive.Trigger>
+      {trailing}
     </AccordionPrimitive.Header>
   );
 }