diff --git a/src/app/api/workspaces/[workspaceId]/search/route.ts b/src/app/api/workspaces/[workspaceId]/search/route.ts
new file mode 100644
index 0000000..d7c0a19
--- /dev/null
+++ b/src/app/api/workspaces/[workspaceId]/search/route.ts
@@ -0,0 +1,287 @@
+// 현재 워크스페이스 멤버만 공지·자료실·업무·채팅을 통합 검색할 수 있는 Route Handler입니다.
+import { NextResponse, type NextRequest } from 'next/server';
+import { z } from 'zod';
+import type { WorkspaceSearchResult } from '@/entities/workspace-search';
+import { getCurrentUserId } from '@/shared/api/supabase/current-user';
+import { createSupabaseServerClient } from '@/shared/api/supabase/server';
+
+const requestSchema = z.object({
+  workspaceId: z.guid(),
+  query: z.string().trim().max(100),
+});
+const SEARCH_RESULT_LIMIT = 5;
+
+type SearchableRow = { id: string; title: string; description: string | null };
+
+function escapeLikePattern(query: string): string {
+  return query.replace(/\\/g, '\\\\').replace(/%/g, '\\%').replace(/_/g, '\\_');
+}
+
+function mergeRows(...groups: SearchableRow[][]): SearchableRow[] {
+  const rowById = new Map<string, SearchableRow>();
+  groups.flat().forEach((row) => rowById.set(row.id, row));
+  return [...rowById.values()].slice(0, SEARCH_RESULT_LIMIT);
+}
+
+function getTaskHref(workspaceId: string, purpose: string): string {
+  if (purpose === 'side_project') return `/workspaces/${workspaceId}/sprint-board`;
+  if (purpose === 'team_project') return `/workspaces/${workspaceId}/project-management`;
+  return `/workspaces/${workspaceId}/dashboard`;
+}
+
+export async function GET(
+  request: NextRequest,
+  context: { params: Promise<{ workspaceId: string }> },
+) {
+  const { workspaceId } = await context.params;
+  const parsed = requestSchema.safeParse({
+    workspaceId,
+    query: request.nextUrl.searchParams.get('q') ?? '',
+  });
+
+  if (!parsed.success) {
+    return NextResponse.json(
+      { message: '검색어 또는 워크스페이스 정보가 올바르지 않습니다.' },
+      { status: 400 },
+    );
+  }
+
+  if (parsed.data.query.length < 2) {
+    return NextResponse.json({ results: [] satisfies WorkspaceSearchResult[] });
+  }
+
+  try {
+    const supabase = await createSupabaseServerClient();
+    // 모든 검색 원본을 현재 사용자와 선택한 워크스페이스 범위로 제한하는 기준값입니다.
+    const currentUserId = await getCurrentUserId();
+    const [
+      { data: membership, error: membershipError },
+      { data: workspace, error: workspaceError },
+    ] = await Promise.all([
+      supabase
+        .from('workspace_members')
+        .select('user_id')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .eq('user_id', currentUserId)
+        .maybeSingle(),
+      supabase.from('workspaces').select('purpose').eq('id', parsed.data.workspaceId).maybeSingle(),
+    ]);
+
+    if (membershipError || workspaceError) {
+      console.error('[workspace search] 권한 확인 실패:', membershipError ?? workspaceError);
+      return NextResponse.json({ message: '검색 권한을 확인하지 못했습니다.' }, { status: 500 });
+    }
+
+    if (!membership || !workspace) {
+      return NextResponse.json(
+        { message: '워크스페이스 멤버만 검색할 수 있습니다.' },
+        { status: 403 },
+      );
+    }
+
+    const pattern = `%${escapeLikePattern(parsed.data.query)}%`;
+    const [
+      announcementTitle,
+      announcementContent,
+      resourceTitle,
+      resourceDescription,
+      taskTitle,
+      taskDescription,
+      chatContent,
+      meetingNoteTitle,
+      meetingNoteContent,
+      calendarEventTitle,
+      calendarEventDescription,
+    ] = await Promise.all([
+      supabase
+        .from('announcements')
+        .select('id, title, content')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('title', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('announcements')
+        .select('id, title, content')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('content', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('resources')
+        .select('id, title, description')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('title', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('resources')
+        .select('id, title, description')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('description', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('tasks')
+        .select('id, title, description')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('title', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('tasks')
+        .select('id, title, description')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('description', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('chat_messages')
+        .select('id, content')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('content', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('meeting_notes')
+        .select('id, title, content')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('title', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('meeting_notes')
+        .select('id, title, content')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('content', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('calendar_events')
+        .select('id, title, description')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('title', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+      supabase
+        .from('calendar_events')
+        .select('id, title, description')
+        .eq('workspace_id', parsed.data.workspaceId)
+        .ilike('description', pattern)
+        .limit(SEARCH_RESULT_LIMIT),
+    ]);
+
+    const errors = [
+      announcementTitle.error,
+      announcementContent.error,
+      resourceTitle.error,
+      resourceDescription.error,
+      taskTitle.error,
+      taskDescription.error,
+      chatContent.error,
+      meetingNoteTitle.error,
+      meetingNoteContent.error,
+      calendarEventTitle.error,
+      calendarEventDescription.error,
+    ];
+
+    if (errors.some(Boolean)) {
+      console.error('[workspace search] 검색 조회 실패:', errors.find(Boolean));
+      return NextResponse.json({ message: '검색 결과를 불러오지 못했습니다.' }, { status: 500 });
+    }
+
+    const announcementRows = mergeRows(
+      (announcementTitle.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.content,
+      })),
+      (announcementContent.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.content,
+      })),
+    );
+    const resourceRows = mergeRows(
+      (resourceTitle.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.description,
+      })),
+      (resourceDescription.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.description,
+      })),
+    );
+    const taskRows = mergeRows(
+      (taskTitle.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.description,
+      })),
+      (taskDescription.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.description,
+      })),
+    );
+    const chatRows = (chatContent.data ?? []).map((row) => ({
+      id: row.id,
+      title: row.content,
+      description: null,
+    }));
+    const meetingNoteRows = mergeRows(
+      (meetingNoteTitle.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.content,
+      })),
+      (meetingNoteContent.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.content,
+      })),
+    );
+    const calendarEventRows = mergeRows(
+      (calendarEventTitle.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.description,
+      })),
+      (calendarEventDescription.data ?? []).map((row) => ({
+        id: row.id,
+        title: row.title,
+        description: row.description,
+      })),
+    );
+
+    const results: WorkspaceSearchResult[] = [
+      ...announcementRows.map((row) => ({
+        ...row,
+        type: 'announcement' as const,
+        href: `/workspaces/${parsed.data.workspaceId}/notices`,
+      })),
+      ...resourceRows.map((row) => ({
+        ...row,
+        type: 'resource' as const,
+        href: `/workspaces/${parsed.data.workspaceId}/files`,
+      })),
+      ...taskRows.map((row) => ({
+        ...row,
+        type: 'task' as const,
+        href: getTaskHref(parsed.data.workspaceId, workspace.purpose),
+      })),
+      ...chatRows.map((row) => ({
+        ...row,
+        type: 'chat' as const,
+        href: `/workspaces/${parsed.data.workspaceId}/chat`,
+      })),
+      ...meetingNoteRows.map((row) => ({
+        ...row,
+        type: 'meetingNote' as const,
+        href: `/workspaces/${parsed.data.workspaceId}/meeting-notes`,
+      })),
+      ...calendarEventRows.map((row) => ({
+        ...row,
+        type: 'calendarEvent' as const,
+        href: `/workspaces/${parsed.data.workspaceId}/calendar`,
+      })),
+    ];
+
+    return NextResponse.json({ results });
+  } catch (error) {
+    console.error('[workspace search] 예상하지 못한 오류:', error);
+    return NextResponse.json({ message: '검색 결과를 불러오지 못했습니다.' }, { status: 500 });
+  }
+}
diff --git a/src/entities/notification/api/get-notifications.ts b/src/entities/notification/api/get-notifications.ts
new file mode 100644
index 0000000..c70ab2e
--- /dev/null
+++ b/src/entities/notification/api/get-notifications.ts
@@ -0,0 +1,60 @@
+'use server';
+
+// 현재 사용자가 수신한 워크스페이스 알림 최근 10건과 읽지 않은 개수를 조회합니다.
+import { z } from 'zod';
+import { getCurrentUserId } from '@/shared/api/supabase/current-user';
+import { createSupabaseServerClient } from '@/shared/api/supabase/server';
+import type {
+  NotificationData,
+  NotificationItem,
+  NotificationType,
+} from '../model/notification.types';
+
+const workspaceIdSchema = z.guid();
+
+function toNotificationItem(row: {
+  id: string;
+  workspace_id: string;
+  type: string;
+  title: string;
+  body: string | null;
+  link_path: string;
+  read_at: string | null;
+  created_at: string;
+}): NotificationItem {
+  return {
+    id: row.id,
+    workspaceId: row.workspace_id,
+    type: row.type as NotificationType,
+    title: row.title,
+    body: row.body,
+    linkPath: row.link_path,
+    readAt: row.read_at,
+    createdAt: row.created_at,
+  };
+}
+
+export async function getNotifications(workspaceId: string): Promise<NotificationData> {
+  const parsedWorkspaceId = workspaceIdSchema.parse(workspaceId);
+  const supabase = await createSupabaseServerClient();
+  // 현재 사용자가 수신자인 알림만 조회하기 위한 세션 사용자 ID입니다.
+  const currentUserId = await getCurrentUserId();
+  const { data, error } = await supabase
+    .from('notifications')
+    .select('id, workspace_id, type, title, body, link_path, read_at, created_at')
+    .eq('workspace_id', parsedWorkspaceId)
+    .eq('recipient_id', currentUserId)
+    .order('created_at', { ascending: false })
+    .limit(10);
+
+  if (error) {
+    console.error('[notification] 알림 조회 실패:', error);
+    throw new Error('알림을 불러오지 못했습니다.');
+  }
+
+  const notifications = (data ?? []).map(toNotificationItem);
+  return {
+    notifications,
+    unreadCount: notifications.filter((notification) => !notification.readAt).length,
+  };
+}
diff --git a/src/entities/notification/api/notification-actions.ts b/src/entities/notification/api/notification-actions.ts
new file mode 100644
index 0000000..402aa5e
--- /dev/null
+++ b/src/entities/notification/api/notification-actions.ts
@@ -0,0 +1,51 @@
+'use server';
+
+// 현재 사용자가 수신한 알림을 개별 또는 일괄 읽음 처리합니다.
+import { z } from 'zod';
+import { getCurrentUserId } from '@/shared/api/supabase/current-user';
+import { createSupabaseServerClient } from '@/shared/api/supabase/server';
+import type { NotificationActionResult } from '../model/notification.types';
+
+const markNotificationsReadSchema = z.object({
+  workspaceId: z.guid(),
+  notificationIds: z.array(z.guid()).min(1).optional(),
+});
+
+export async function markNotificationsRead(input: {
+  workspaceId: string;
+  notificationIds?: string[];
+}): Promise<NotificationActionResult<void>> {
+  const parsed = markNotificationsReadSchema.safeParse(input);
+
+  if (!parsed.success) {
+    return { ok: false, message: '읽음 처리할 알림 정보가 올바르지 않습니다.' };
+  }
+
+  try {
+    const supabase = await createSupabaseServerClient();
+    // 수신자 본인의 미읽음 알림만 수정하기 위한 세션 사용자 ID입니다.
+    const currentUserId = await getCurrentUserId();
+    let query = supabase
+      .from('notifications')
+      .update({ read_at: new Date().toISOString() })
+      .eq('workspace_id', parsed.data.workspaceId)
+      .eq('recipient_id', currentUserId)
+      .is('read_at', null);
+
+    if (parsed.data.notificationIds) {
+      query = query.in('id', parsed.data.notificationIds);
+    }
+
+    const { error } = await query;
+
+    if (error) {
+      console.error('[notification] 읽음 처리 실패:', error);
+      return { ok: false, message: '알림 읽음 처리에 실패했습니다.' };
+    }
+
+    return { ok: true, data: undefined };
+  } catch (error) {
+    console.error('[notification] 읽음 처리 중 예상하지 못한 오류:', error);
+    return { ok: false, message: '알림 읽음 처리에 실패했습니다.' };
+  }
+}
diff --git a/src/entities/notification/index.ts b/src/entities/notification/index.ts
new file mode 100644
index 0000000..00a505f
--- /dev/null
+++ b/src/entities/notification/index.ts
@@ -0,0 +1,10 @@
+// 알림 도메인이 헤더 기능에 제공하는 조회·읽음 API와 타입 공개 진입점입니다.
+export { getNotifications } from './api/get-notifications';
+export { markNotificationsRead } from './api/notification-actions';
+export { notificationsQueryKey } from './model/notification-query';
+export type {
+  NotificationActionResult,
+  NotificationData,
+  NotificationItem,
+  NotificationType,
+} from './model/notification.types';
diff --git a/src/entities/notification/model/notification-query.ts b/src/entities/notification/model/notification-query.ts
new file mode 100644
index 0000000..47990af
--- /dev/null
+++ b/src/entities/notification/model/notification-query.ts
@@ -0,0 +1,3 @@
+// 워크스페이스별 알림 목록과 읽지 않은 개수를 함께 갱신하기 위한 Query 키입니다.
+export const notificationsQueryKey = (workspaceId: string) =>
+  ['notifications', workspaceId] as const;
diff --git a/src/entities/notification/model/notification.types.ts b/src/entities/notification/model/notification.types.ts
new file mode 100644
index 0000000..3a37a31
--- /dev/null
+++ b/src/entities/notification/model/notification.types.ts
@@ -0,0 +1,20 @@
+// 헤더 알림 목록과 읽음 처리에서 공통으로 사용하는 알림 도메인 타입입니다.
+export type NotificationType = 'announcement_created' | 'task_assigned' | 'task_status_changed';
+
+export interface NotificationItem {
+  id: string;
+  workspaceId: string;
+  type: NotificationType;
+  title: string;
+  body: string | null;
+  linkPath: string;
+  readAt: string | null;
+  createdAt: string;
+}
+
+export interface NotificationData {
+  notifications: NotificationItem[];
+  unreadCount: number;
+}
+
+export type NotificationActionResult<T> = { ok: true; data: T } | { ok: false; message: string };
diff --git a/src/entities/workspace-search/api/search-workspace.ts b/src/entities/workspace-search/api/search-workspace.ts
new file mode 100644
index 0000000..8b37aa2
--- /dev/null
+++ b/src/entities/workspace-search/api/search-workspace.ts
@@ -0,0 +1,20 @@
+// 헤더의 TanStack Query가 워크스페이스 통합 검색 Route Handler를 호출하는 클라이언트 API입니다.
+import type { WorkspaceSearchResult } from '../model/workspace-search.types';
+
+export async function searchWorkspace(input: {
+  workspaceId: string;
+  query: string;
+  signal?: AbortSignal;
+}): Promise<WorkspaceSearchResult[]> {
+  const searchParams = new URLSearchParams({ q: input.query });
+  const response = await fetch(`/api/workspaces/${input.workspaceId}/search?${searchParams}`, {
+    signal: input.signal,
+  });
+
+  if (!response.ok) {
+    throw new Error('검색 결과를 불러오지 못했습니다.');
+  }
+
+  const payload = (await response.json()) as { results: WorkspaceSearchResult[] };
+  return payload.results;
+}
diff --git a/src/entities/workspace-search/index.ts b/src/entities/workspace-search/index.ts
new file mode 100644
index 0000000..ea78aca
--- /dev/null
+++ b/src/entities/workspace-search/index.ts
@@ -0,0 +1,4 @@
+// 워크스페이스 통합 검색 도메인의 타입과 Query 키 공개 진입점입니다.
+export { searchWorkspace } from './api/search-workspace';
+export { workspaceSearchQueryKey } from './model/workspace-search-query';
+export type { WorkspaceSearchResult, WorkspaceSearchType } from './model/workspace-search.types';
diff --git a/src/entities/workspace-search/model/workspace-search-query.ts b/src/entities/workspace-search/model/workspace-search-query.ts
new file mode 100644
index 0000000..bce2495
--- /dev/null
+++ b/src/entities/workspace-search/model/workspace-search-query.ts
@@ -0,0 +1,3 @@
+// 워크스페이스와 검색어별로 결과 캐시를 분리하기 위한 TanStack Query 키입니다.
+export const workspaceSearchQueryKey = (workspaceId: string, query: string) =>
+  ['workspace-search', workspaceId, query] as const;
diff --git a/src/entities/workspace-search/model/workspace-search.types.ts b/src/entities/workspace-search/model/workspace-search.types.ts
new file mode 100644
index 0000000..b1b2e4a
--- /dev/null
+++ b/src/entities/workspace-search/model/workspace-search.types.ts
@@ -0,0 +1,11 @@
+// 워크스페이스 통합 검색 결과를 모든 검색 원본에서 동일하게 표현합니다.
+export type WorkspaceSearchType =
+  'announcement' | 'resource' | 'task' | 'chat' | 'meetingNote' | 'calendarEvent';
+
+export interface WorkspaceSearchResult {
+  id: string;
+  type: WorkspaceSearchType;
+  title: string;
+  description: string | null;
+  href: string;
+}
diff --git a/src/features/workspace-notifications/index.ts b/src/features/workspace-notifications/index.ts
new file mode 100644
index 0000000..9fc9389
--- /dev/null
+++ b/src/features/workspace-notifications/index.ts
@@ -0,0 +1,2 @@
+// 헤더가 사용하는 워크스페이스 알림 UI 공개 진입점입니다.
+export { NotificationPanel } from './ui/NotificationPanel';
diff --git a/src/features/workspace-notifications/model/use-workspace-notifications.ts b/src/features/workspace-notifications/model/use-workspace-notifications.ts
new file mode 100644
index 0000000..2caa95d
--- /dev/null
+++ b/src/features/workspace-notifications/model/use-workspace-notifications.ts
@@ -0,0 +1,123 @@
+'use client';
+
+// 알림 목록 캐시, 읽음 처리 mutation, Supabase Realtime INSERT 구독을 한 곳에서 관리합니다.
+import { useEffect } from 'react';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
+import {
+  getNotifications,
+  markNotificationsRead,
+  notificationsQueryKey,
+  type NotificationData,
+  type NotificationItem,
+  type NotificationType,
+} from '@/entities/notification';
+import { getSupabaseBrowserClient } from '@/shared/api/supabase/client';
+import type { GenericTables } from '@/shared/model/supabase.types';
+
+type NotificationRow = GenericTables<'notifications'>;
+
+function toNotificationItem(row: NotificationRow): NotificationItem {
+  return {
+    id: row.id,
+    workspaceId: row.workspace_id,
+    type: row.type as NotificationType,
+    title: row.title,
+    body: row.body,
+    linkPath: row.link_path,
+    readAt: row.read_at,
+    createdAt: row.created_at,
+  };
+}
+
+function addNotification(
+  currentData: NotificationData | undefined,
+  notification: NotificationItem,
+): NotificationData | undefined {
+  if (!currentData || currentData.notifications.some((item) => item.id === notification.id)) {
+    return currentData;
+  }
+
+  return {
+    notifications: [notification, ...currentData.notifications].slice(0, 10),
+    unreadCount: currentData.unreadCount + (notification.readAt ? 0 : 1),
+  };
+}
+
+export function useWorkspaceNotifications({
+  workspaceId,
+  viewerId,
+}: {
+  workspaceId: string;
+  viewerId: string;
+}) {
+  // 동일 워크스페이스의 헤더 알림 UI를 함께 갱신하기 위한 TanStack Query 클라이언트입니다.
+  const queryClient = useQueryClient();
+  const notificationQuery = useQuery({
+    queryKey: notificationsQueryKey(workspaceId),
+    queryFn: () => getNotifications(workspaceId),
+  });
+  const markReadMutation = useMutation({
+    mutationFn: (notificationIds?: string[]) =>
+      markNotificationsRead({ workspaceId, notificationIds }),
+    onSuccess: (result, notificationIds) => {
+      if (!result.ok) return;
+
+      const readAt = new Date().toISOString();
+      queryClient.setQueryData<NotificationData>(
+        notificationsQueryKey(workspaceId),
+        (currentData) => {
+          if (!currentData) return currentData;
+          const shouldMarkRead = (notification: NotificationItem) =>
+            !notification.readAt && (!notificationIds || notificationIds.includes(notification.id));
+          const notifications = currentData.notifications.map((notification) =>
+            shouldMarkRead(notification) ? { ...notification, readAt } : notification,
+          );
+
+          return {
+            notifications,
+            unreadCount: notifications.filter((notification) => !notification.readAt).length,
+          };
+        },
+      );
+    },
+  });
+
+  useEffect(() => {
+    // RLS와 recipient_id를 함께 확인해 현재 사용자에게 도착한 이벤트만 캐시에 넣습니다.
+    const supabase = getSupabaseBrowserClient();
+    const channel = supabase
+      .channel(`workspace-notifications:${workspaceId}`)
+      .on(
+        'postgres_changes',
+        {
+          event: 'INSERT',
+          schema: 'public',
+          table: 'notifications',
+          filter: `workspace_id=eq.${workspaceId}`,
+        },
+        (payload) => {
+          const row = payload.new as NotificationRow;
+          if (row.recipient_id !== viewerId) return;
+
+          queryClient.setQueryData<NotificationData>(
+            notificationsQueryKey(workspaceId),
+            (currentData) => addNotification(currentData, toNotificationItem(row)),
+          );
+        },
+      )
+      .subscribe();
+
+    return () => {
+      void supabase.removeChannel(channel);
+    };
+  }, [queryClient, viewerId, workspaceId]);
+
+  return {
+    notifications: notificationQuery.data?.notifications ?? [],
+    unreadCount: notificationQuery.data?.unreadCount ?? 0,
+    isLoading: notificationQuery.isPending,
+    isError: notificationQuery.isError,
+    markOneAsRead: async (notificationId: string) => markReadMutation.mutateAsync([notificationId]),
+    markAllAsRead: async () => markReadMutation.mutateAsync(undefined),
+  };
+}
diff --git a/src/features/workspace-notifications/ui/NotificationPanel.tsx b/src/features/workspace-notifications/ui/NotificationPanel.tsx
new file mode 100644
index 0000000..84e9a2c
--- /dev/null
+++ b/src/features/workspace-notifications/ui/NotificationPanel.tsx
@@ -0,0 +1,143 @@
+'use client';
+
+// 헤더 종 아이콘에서 최근 알림, 읽지 않은 개수, 읽음 처리 명령을 표시합니다.
+import { Bell, CheckCheck, ClipboardList, Megaphone } from 'lucide-react';
+import Link from 'next/link';
+import { useRouter } from 'next/navigation';
+import { toast } from 'sonner';
+import type { NotificationItem } from '@/entities/notification';
+import { useWorkspaceNotifications } from '../model/use-workspace-notifications';
+
+interface NotificationPanelProps {
+  workspaceId: string;
+  viewerId: string;
+  isOpen: boolean;
+  onOpenChange: (isOpen: boolean) => void;
+}
+
+function getNotificationIcon(type: NotificationItem['type']) {
+  const className = 'h-4 w-4 text-indigo-500';
+  if (type === 'announcement_created')
+    return <Megaphone className={className} aria-hidden="true" />;
+  return <ClipboardList className={className} aria-hidden="true" />;
+}
+
+function formatCreatedAt(value: string): string {
+  return new Intl.DateTimeFormat('ko-KR', {
+    month: 'numeric',
+    day: 'numeric',
+    hour: '2-digit',
+    minute: '2-digit',
+  }).format(new Date(value));
+}
+
+export function NotificationPanel({
+  workspaceId,
+  viewerId,
+  isOpen,
+  onOpenChange,
+}: NotificationPanelProps) {
+  const router = useRouter();
+  const { notifications, unreadCount, isLoading, isError, markOneAsRead, markAllAsRead } =
+    useWorkspaceNotifications({ workspaceId, viewerId });
+
+  const markAll = async () => {
+    const result = await markAllAsRead();
+    if (!result.ok) toast.error(result.message);
+  };
+
+  const openNotification = async (
+    event: React.MouseEvent<HTMLAnchorElement>,
+    notification: NotificationItem,
+  ) => {
+    event.preventDefault();
+    if (!notification.readAt) {
+      const result = await markOneAsRead(notification.id);
+      if (!result.ok) toast.error(result.message);
+    }
+    onOpenChange(false);
+    router.push(notification.linkPath);
+  };
+
+  return (
+    <div className="relative">
+      <button
+        type="button"
+        aria-label="알림"
+        aria-expanded={isOpen}
+        onClick={() => onOpenChange(!isOpen)}
+        className="relative flex h-10 w-10 items-center justify-center rounded-full text-slate-500 hover:bg-slate-100"
+      >
+        <Bell className="h-5 w-5" aria-hidden="true" />
+        {unreadCount > 0 && (
+          <span className="absolute top-1 right-1 flex min-w-4 items-center justify-center rounded-full bg-rose-500 px-1 text-[10px] font-bold text-white">
+            {unreadCount > 9 ? '9+' : unreadCount}
+          </span>
+        )}
+      </button>
+
+      {isOpen && (
+        <div className="absolute top-12 right-0 z-50 w-[min(24rem,calc(100vw-2rem))] overflow-hidden rounded-xl border border-slate-200 bg-white shadow-xl">
+          <div className="flex items-center justify-between border-b border-slate-100 px-4 py-3">
+            <div>
+              <p className="text-sm font-bold text-slate-900">알림</p>
+              <p className="text-xs text-slate-500">최근 알림 10개</p>
+            </div>
+            <button
+              type="button"
+              onClick={() => void markAll()}
+              disabled={unreadCount === 0}
+              className="flex items-center gap-1 text-xs font-semibold text-indigo-600 disabled:text-slate-300"
+            >
+              <CheckCheck className="h-4 w-4" aria-hidden="true" />
+              전체 읽음
+            </button>
+          </div>
+
+          <div className="max-h-96 overflow-y-auto">
+            {isLoading && (
+              <p className="px-4 py-5 text-sm text-slate-500">알림을 불러오는 중입니다.</p>
+            )}
+            {!isLoading && isError && (
+              <p className="px-4 py-5 text-sm text-rose-600">알림을 불러오지 못했습니다.</p>
+            )}
+            {!isLoading && !isError && notifications.length === 0 && (
+              <p className="px-4 py-5 text-sm text-slate-500">새 알림이 없습니다.</p>
+            )}
+            {notifications.map((notification) => (
+              <Link
+                key={notification.id}
+                href={notification.linkPath}
+                onClick={(event) => void openNotification(event, notification)}
+                className={`flex gap-3 border-b border-slate-100 px-4 py-3 last:border-0 hover:bg-slate-50 ${
+                  notification.readAt ? 'opacity-70' : 'bg-indigo-50/40'
+                }`}
+              >
+                <span className="mt-0.5">{getNotificationIcon(notification.type)}</span>
+                <span className="min-w-0 flex-1">
+                  <span className="block truncate text-sm font-semibold text-slate-800">
+                    {notification.title}
+                  </span>
+                  {notification.body && (
+                    <span className="mt-0.5 block truncate text-xs text-slate-500">
+                      {notification.body}
+                    </span>
+                  )}
+                  <time
+                    className="mt-1 block text-xs text-slate-400"
+                    dateTime={notification.createdAt}
+                  >
+                    {formatCreatedAt(notification.createdAt)}
+                  </time>
+                </span>
+                {!notification.readAt && (
+                  <span className="mt-1 h-2 w-2 rounded-full bg-indigo-500" />
+                )}
+              </Link>
+            ))}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}
diff --git a/src/features/workspace-search/index.ts b/src/features/workspace-search/index.ts
new file mode 100644
index 0000000..b34da41
--- /dev/null
+++ b/src/features/workspace-search/index.ts
@@ -0,0 +1,2 @@
+// 헤더가 사용하는 워크스페이스 통합 검색 UI 공개 진입점입니다.
+export { WorkspaceSearchPanel } from './ui/WorkspaceSearchPanel';
diff --git a/src/features/workspace-search/model/use-workspace-search.ts b/src/features/workspace-search/model/use-workspace-search.ts
new file mode 100644
index 0000000..2e32197
--- /dev/null
+++ b/src/features/workspace-search/model/use-workspace-search.ts
@@ -0,0 +1,37 @@
+'use client';
+
+// 헤더 검색어를 debounce하고 Route Handler 결과를 TanStack Query 캐시로 관리합니다.
+import { useEffect, useState } from 'react';
+import { useQuery } from '@tanstack/react-query';
+import { searchWorkspace, workspaceSearchQueryKey } from '@/entities/workspace-search';
+
+const SEARCH_DEBOUNCE_MS = 300;
+
+export function useWorkspaceSearch(workspaceId: string) {
+  // 사용자가 즉시 입력하는 원본 검색어와 서버 요청에 쓰는 debounce 검색어를 분리합니다.
+  const [query, setQuery] = useState('');
+  const [debouncedQuery, setDebouncedQuery] = useState('');
+
+  useEffect(() => {
+    const timeoutId = window.setTimeout(() => setDebouncedQuery(query.trim()), SEARCH_DEBOUNCE_MS);
+    return () => window.clearTimeout(timeoutId);
+  }, [query]);
+
+  const normalizedQuery = debouncedQuery.trim();
+  const searchQuery = useQuery({
+    queryKey: workspaceSearchQueryKey(workspaceId, normalizedQuery),
+    queryFn: ({ signal }) => searchWorkspace({ workspaceId, query: normalizedQuery, signal }),
+    enabled: normalizedQuery.length >= 2,
+    staleTime: 30_000,
+  });
+
+  return {
+    query,
+    setQuery,
+    normalizedQuery,
+    results: searchQuery.data ?? [],
+    isLoading:
+      searchQuery.isPending || (query.trim().length >= 2 && query.trim() !== normalizedQuery),
+    isError: searchQuery.isError,
+  };
+}
diff --git a/src/features/workspace-search/ui/WorkspaceSearchPanel.tsx b/src/features/workspace-search/ui/WorkspaceSearchPanel.tsx
new file mode 100644
index 0000000..c9ae261
--- /dev/null
+++ b/src/features/workspace-search/ui/WorkspaceSearchPanel.tsx
@@ -0,0 +1,124 @@
+'use client';
+
+// 헤더 입력창과 워크스페이스 통합 검색 결과 목록을 렌더링합니다.
+import {
+  CalendarDays,
+  FileText,
+  MessageSquare,
+  NotebookPen,
+  Search,
+  SquareCheckBig,
+} from 'lucide-react';
+import Link from 'next/link';
+import { useWorkspaceSearch } from '../model/use-workspace-search';
+
+interface WorkspaceSearchPanelProps {
+  workspaceId: string;
+  isOpen: boolean;
+  onOpenChange: (isOpen: boolean) => void;
+}
+
+const SEARCH_TYPE_LABEL = {
+  announcement: '공지',
+  resource: '자료실',
+  task: '업무',
+  chat: '채팅',
+  meetingNote: '회의록',
+  calendarEvent: '일정',
+} as const;
+
+function SearchTypeIcon({ type }: { type: keyof typeof SEARCH_TYPE_LABEL }) {
+  const className = 'h-4 w-4 text-slate-400';
+  if (type === 'announcement') return <SquareCheckBig className={className} aria-hidden="true" />;
+  if (type === 'resource') return <FileText className={className} aria-hidden="true" />;
+  if (type === 'chat') return <MessageSquare className={className} aria-hidden="true" />;
+  if (type === 'meetingNote') return <NotebookPen className={className} aria-hidden="true" />;
+  if (type === 'calendarEvent') return <CalendarDays className={className} aria-hidden="true" />;
+  return <SquareCheckBig className={className} aria-hidden="true" />;
+}
+
+export function WorkspaceSearchPanel({
+  workspaceId,
+  isOpen,
+  onOpenChange,
+}: WorkspaceSearchPanelProps) {
+  const { query, setQuery, normalizedQuery, results, isLoading, isError } =
+    useWorkspaceSearch(workspaceId);
+
+  return (
+    <div className="relative w-48 sm:w-60">
+      <label className="flex h-10 items-center gap-2 rounded-xl bg-slate-100 px-4 text-slate-400 focus-within:ring-2 focus-within:ring-indigo-200">
+        <Search className="h-4 w-4 shrink-0" aria-hidden="true" />
+        <input
+          type="search"
+          value={query}
+          onFocus={() => onOpenChange(true)}
+          onChange={(event) => {
+            setQuery(event.target.value);
+            onOpenChange(true);
+          }}
+          onKeyDown={(event) => {
+            if (event.key === 'Escape') onOpenChange(false);
+          }}
+          placeholder="검색..."
+          className="min-w-0 flex-1 bg-transparent text-sm font-medium text-slate-700 outline-none placeholder:text-slate-400"
+          aria-label="워크스페이스 통합 검색"
+          aria-autocomplete="list"
+          aria-expanded={isOpen}
+          aria-controls="workspace-search-results"
+          role="combobox"
+        />
+      </label>
+
+      {isOpen && (
+        <div
+          id="workspace-search-results"
+          className="absolute top-12 right-0 z-50 w-[min(24rem,calc(100vw-2rem))] overflow-hidden rounded-xl border border-slate-200 bg-white shadow-xl"
+        >
+          {query.trim().length < 2 && (
+            <p className="px-4 py-4 text-sm text-slate-500">두 글자 이상 입력해 검색하세요.</p>
+          )}
+          {query.trim().length >= 2 && isLoading && (
+            <p className="px-4 py-4 text-sm text-slate-500">검색 중입니다.</p>
+          )}
+          {query.trim().length >= 2 && !isLoading && isError && (
+            <p className="px-4 py-4 text-sm text-rose-600">검색 결과를 불러오지 못했습니다.</p>
+          )}
+          {normalizedQuery.length >= 2 && !isLoading && !isError && results.length === 0 && (
+            <p className="px-4 py-4 text-sm text-slate-500">검색 결과가 없습니다.</p>
+          )}
+          {results.length > 0 && (
+            <ul className="max-h-96 overflow-y-auto py-1">
+              {results.map((result) => (
+                <li key={`${result.type}-${result.id}`}>
+                  <Link
+                    href={result.href}
+                    onClick={() => onOpenChange(false)}
+                    className="flex items-start gap-3 px-4 py-3 hover:bg-slate-50"
+                  >
+                    <SearchTypeIcon type={result.type} />
+                    <span className="min-w-0 flex-1">
+                      <span className="mb-1 flex items-center gap-2">
+                        <span className="rounded bg-indigo-50 px-1.5 py-0.5 text-xs font-semibold text-indigo-600">
+                          {SEARCH_TYPE_LABEL[result.type]}
+                        </span>
+                        <span className="truncate text-sm font-semibold text-slate-800">
+                          {result.title}
+                        </span>
+                      </span>
+                      {result.description && (
+                        <span className="block truncate text-xs text-slate-500">
+                          {result.description}
+                        </span>
+                      )}
+                    </span>
+                  </Link>
+                </li>
+              ))}
+            </ul>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}
diff --git a/src/shared/model/database.types.ts b/src/shared/model/database.types.ts
index 58fe676..09ef5a6 100644
--- a/src/shared/model/database.types.ts
+++ b/src/shared/model/database.types.ts
@@ -255,6 +255,70 @@ export type Database = {
         }
         Relationships: []
       }
+      notifications: {
+        Row: {
+          actor_id: string | null
+          body: string | null
+          created_at: string
+          id: string
+          link_path: string
+          metadata: Json
+          read_at: string | null
+          recipient_id: string
+          title: string
+          type: string
+          workspace_id: string
+        }
+        Insert: {
+          actor_id?: string | null
+          body?: string | null
+          created_at?: string
+          id?: string
+          link_path: string
+          metadata?: Json
+          read_at?: string | null
+          recipient_id: string
+          title: string
+          type: string
+          workspace_id: string
+        }
+        Update: {
+          actor_id?: string | null
+          body?: string | null
+          created_at?: string
+          id?: string
+          link_path?: string
+          metadata?: Json
+          read_at?: string | null
+          recipient_id?: string
+          title?: string
+          type?: string
+          workspace_id?: string
+        }
+        Relationships: [
+          {
+            foreignKeyName: "notifications_actor_id_fkey"
+            columns: ["actor_id"]
+            isOneToOne: false
+            referencedRelation: "profiles"
+            referencedColumns: ["id"]
+          },
+          {
+            foreignKeyName: "notifications_recipient_id_fkey"
+            columns: ["recipient_id"]
+            isOneToOne: false
+            referencedRelation: "profiles"
+            referencedColumns: ["id"]
+          },
+          {
+            foreignKeyName: "notifications_workspace_id_fkey"
+            columns: ["workspace_id"]
+            isOneToOne: false
+            referencedRelation: "workspaces"
+            referencedColumns: ["id"]
+          },
+        ]
+      }
       profiles: {
         Row: {
           avatar_url: string | null
diff --git a/src/widgets/workspace-shell/ui/WorkspaceHeader.tsx b/src/widgets/workspace-shell/ui/WorkspaceHeader.tsx
index e2f21f3..346c331 100644
--- a/src/widgets/workspace-shell/ui/WorkspaceHeader.tsx
+++ b/src/widgets/workspace-shell/ui/WorkspaceHeader.tsx
@@ -1,11 +1,13 @@
 'use client';
 
 // 하나의 워크스페이스 내부 페이지에서 공통으로 사용하는 상단 헤더입니다.
-import { Bell, LogOut, Search, Settings, UserRoundPlus } from 'lucide-react';
+import { LogOut, Settings, UserRoundPlus } from 'lucide-react';
 import Link from 'next/link';
 import { usePathname } from 'next/navigation';
 import { useEffect, useRef, useState } from 'react';
 import type { WorkspaceMember } from '@/entities/workspace-member';
+import { WorkspaceSearchPanel } from '@/features/workspace-search';
+import { NotificationPanel } from '@/features/workspace-notifications';
 import { useLogout } from '@/shared/lib/use-logout';
 import { cn } from '@/shared/lib/utils';
 import type { WorkspaceNavigationItem } from '../model/workspace-navigation';
@@ -29,56 +31,92 @@ export function WorkspaceHeader({
   const pathname = usePathname();
   const title = getCurrentPageTitle(pathname, navigationItems);
   const [isMenuOpen, setIsMenuOpen] = useState(false);
+  const [isSearchOpen, setIsSearchOpen] = useState(false);
+  const [isNotificationOpen, setIsNotificationOpen] = useState(false);
   const menuRef = useRef<HTMLDivElement>(null);
+  const searchRef = useRef<HTMLDivElement>(null);
+  const notificationRef = useRef<HTMLDivElement>(null);
 
   useEffect(() => {
-    if (!isMenuOpen) return;
+    if (!isMenuOpen && !isSearchOpen && !isNotificationOpen) return;
     const handleClickOutside = (e: MouseEvent) => {
-      if (menuRef.current && !menuRef.current.contains(e.target as Node)) {
+      const target = e.target as Node;
+      if (menuRef.current && !menuRef.current.contains(target)) {
         setIsMenuOpen(false);
       }
+      if (searchRef.current && !searchRef.current.contains(target)) setIsSearchOpen(false);
+      if (notificationRef.current && !notificationRef.current.contains(target)) {
+        setIsNotificationOpen(false);
+      }
     };
     document.addEventListener('mousedown', handleClickOutside);
     return () => document.removeEventListener('mousedown', handleClickOutside);
-  }, [isMenuOpen]);
+  }, [isMenuOpen, isNotificationOpen, isSearchOpen]);
+
+  useEffect(() => {
+    const handleEscape = (event: KeyboardEvent) => {
+      if (event.key !== 'Escape') return;
+      setIsSearchOpen(false);
+      setIsNotificationOpen(false);
+      setIsMenuOpen(false);
+    };
+
+    document.addEventListener('keydown', handleEscape);
+    return () => document.removeEventListener('keydown', handleEscape);
+  }, []);
 
   const { handleLogout } = useLogout();
 
   return (
-    <header className="flex h-[72px] items-center justify-between border-b border-slate-200 bg-white px-8">
-      <h1 className="text-lg font-bold text-slate-950">{title}</h1>
+    <header className="flex h-[72px] items-center justify-between gap-4 border-b border-slate-200 bg-white px-4 sm:px-8">
+      <h1 className="shrink-0 text-lg font-bold text-slate-950">{title}</h1>
 
-      <div className="flex items-center gap-3">
-        <label className="flex h-10 w-60 items-center gap-2 rounded-2xl bg-slate-100 px-4 text-slate-400">
-          <Search className="h-4 w-4" aria-hidden="true" />
-          <input
-            type="search"
-            placeholder="검색..."
-            className="min-w-0 flex-1 bg-transparent text-sm font-medium text-slate-700 outline-none placeholder:text-slate-400"
+      <div className="flex min-w-0 items-center gap-2 sm:gap-3">
+        <div ref={searchRef}>
+          <WorkspaceSearchPanel
+            workspaceId={workspaceId}
+            isOpen={isSearchOpen}
+            onOpenChange={(isOpen) => {
+              setIsSearchOpen(isOpen);
+              if (isOpen) {
+                setIsNotificationOpen(false);
+                setIsMenuOpen(false);
+              }
+            }}
           />
-        </label>
+        </div>
 
-        <button
-          type="button"
-          className="flex h-10 items-center gap-2 rounded-2xl bg-[var(--color-brand)] px-4 text-sm font-bold text-white hover:bg-indigo-500"
+        <Link
+          href={`/workspaces/${workspaceId}/settings?tab=members`}
+          className="flex h-10 shrink-0 items-center gap-2 rounded-xl bg-[var(--color-brand)] px-3 text-sm font-bold whitespace-nowrap text-white hover:bg-indigo-500 sm:px-4"
         >
           <UserRoundPlus className="h-4 w-4" aria-hidden="true" />
-          멤버 초대
-        </button>
+          <span className="hidden sm:inline">멤버 초대</span>
+        </Link>
 
-        <button
-          type="button"
-          aria-label="알림"
-          className="relative flex h-10 w-10 items-center justify-center rounded-full text-slate-500 hover:bg-slate-100"
-        >
-          <Bell className="h-5 w-5" aria-hidden="true" />
-          <span className="absolute top-2 right-2 h-2 w-2 rounded-full bg-rose-500" />
-        </button>
+        <div ref={notificationRef}>
+          <NotificationPanel
+            workspaceId={workspaceId}
+            viewerId={currentMember.userId}
+            isOpen={isNotificationOpen}
+            onOpenChange={(isOpen) => {
+              setIsNotificationOpen(isOpen);
+              if (isOpen) {
+                setIsSearchOpen(false);
+                setIsMenuOpen(false);
+              }
+            }}
+          />
+        </div>
 
         <div ref={menuRef} className="relative">
           <button
             type="button"
-            onClick={() => setIsMenuOpen((v) => !v)}
+            onClick={() => {
+              setIsMenuOpen((value) => !value);
+              setIsSearchOpen(false);
+              setIsNotificationOpen(false);
+            }}
             className="flex h-10 w-10 items-center justify-center rounded-full bg-orange-400 text-sm font-bold text-white hover:opacity-90"
           >
             {currentMember.avatarLabel}
diff --git a/supabase/migrations/20260716030000_create_workspace_notifications.sql b/supabase/migrations/20260716030000_create_workspace_notifications.sql
new file mode 100644
index 0000000..4b7b8d0
--- /dev/null
+++ b/supabase/migrations/20260716030000_create_workspace_notifications.sql
@@ -0,0 +1,217 @@
+-- 워크스페이스별 개인 알림을 저장하고 공지·업무 변경 시 자동 생성한다.
+
+create table public.notifications (
+  id uuid primary key default gen_random_uuid(),
+  recipient_id uuid not null references public.profiles(id) on delete cascade,
+  actor_id uuid references public.profiles(id) on delete set null,
+  workspace_id uuid not null references public.workspaces(id) on delete cascade,
+  type text not null check (type in ('announcement_created', 'task_assigned', 'task_status_changed')),
+  title text not null,
+  body text,
+  link_path text not null,
+  metadata jsonb not null default '{}'::jsonb,
+  read_at timestamptz,
+  created_at timestamptz not null default now()
+);
+
+create index notifications_recipient_created_at_idx
+  on public.notifications (recipient_id, created_at desc);
+
+alter table public.notifications enable row level security;
+
+-- 앱 클라이언트에는 알림 생성·삭제 권한을 부여하지 않고 조회·읽음 처리만 허용한다.
+revoke insert, delete on table public.notifications from anon, authenticated;
+grant select, update on table public.notifications to authenticated;
+
+create policy notifications_select_recipient
+on public.notifications
+for select
+to authenticated
+using (
+  recipient_id = (select auth.uid())
+  and private.is_workspace_member(workspace_id)
+);
+
+create policy notifications_update_recipient_read_state
+on public.notifications
+for update
+to authenticated
+using (
+  recipient_id = (select auth.uid())
+  and private.is_workspace_member(workspace_id)
+)
+with check (
+  recipient_id = (select auth.uid())
+  and private.is_workspace_member(workspace_id)
+);
+
+-- 수신자는 읽음 시각만 변경할 수 있고, 알림의 내용·대상·이동 경로는 불변으로 둔다.
+create function private.prevent_notification_mutation()
+returns trigger
+language plpgsql
+security invoker
+set search_path = ''
+as $$
+begin
+  if new.id is distinct from old.id
+    or new.recipient_id is distinct from old.recipient_id
+    or new.actor_id is distinct from old.actor_id
+    or new.workspace_id is distinct from old.workspace_id
+    or new.type is distinct from old.type
+    or new.title is distinct from old.title
+    or new.body is distinct from old.body
+    or new.link_path is distinct from old.link_path
+    or new.metadata is distinct from old.metadata
+    or new.created_at is distinct from old.created_at then
+    raise exception '알림의 읽음 상태 외 정보는 변경할 수 없습니다.';
+  end if;
+
+  return new;
+end;
+$$;
+
+create trigger prevent_notification_mutation
+before update on public.notifications
+for each row
+execute function private.prevent_notification_mutation();
+
+-- 공지 작성자 이외의 현재 워크스페이스 멤버에게만 공지 알림을 생성한다.
+create function private.create_announcement_notifications()
+returns trigger
+language plpgsql
+security definer
+set search_path = ''
+as $$
+begin
+  insert into public.notifications (
+    recipient_id,
+    actor_id,
+    workspace_id,
+    type,
+    title,
+    body,
+    link_path,
+    metadata
+  )
+  select
+    member.user_id,
+    new.author_id,
+    new.workspace_id,
+    'announcement_created',
+    '새 공지가 등록되었습니다.',
+    new.title,
+    format('/workspaces/%s/notices', new.workspace_id),
+    jsonb_build_object('announcementId', new.id)
+  from public.workspace_members as member
+  where member.workspace_id = new.workspace_id
+    and member.user_id is distinct from new.author_id;
+
+  return new;
+end;
+$$;
+
+revoke all on function private.create_announcement_notifications() from public;
+
+create trigger create_announcement_notifications
+after insert on public.announcements
+for each row
+execute function private.create_announcement_notifications();
+
+-- 업무가 생성·배정되거나 담당 업무 상태가 변경될 때 담당자에게 개인 알림을 생성한다.
+create function private.create_task_assignee_notification()
+returns trigger
+language plpgsql
+security definer
+set search_path = ''
+as $$
+declare
+  v_actor_id uuid := auth.uid();
+  v_link_path text;
+begin
+  select case workspace.purpose
+    when 'side_project' then format('/workspaces/%s/sprint-board', new.workspace_id)
+    when 'team_project' then format('/workspaces/%s/project-management', new.workspace_id)
+    else format('/workspaces/%s/dashboard', new.workspace_id)
+  end
+  into v_link_path
+  from public.workspaces as workspace
+  where workspace.id = new.workspace_id;
+
+  if new.assignee_id is null
+    or new.assignee_id = v_actor_id
+    or not exists (
+      select 1
+      from public.workspace_members as member
+      where member.workspace_id = new.workspace_id
+        and member.user_id = new.assignee_id
+    ) then
+    return new;
+  end if;
+
+  if tg_op = 'INSERT' or new.assignee_id is distinct from old.assignee_id then
+    insert into public.notifications (
+      recipient_id,
+      actor_id,
+      workspace_id,
+      type,
+      title,
+      body,
+      link_path,
+      metadata
+    ) values (
+      new.assignee_id,
+      v_actor_id,
+      new.workspace_id,
+      'task_assigned',
+      '새 업무가 배정되었습니다.',
+      new.title,
+      v_link_path,
+      jsonb_build_object('taskId', new.id)
+    );
+  elsif new.status is distinct from old.status then
+    insert into public.notifications (
+      recipient_id,
+      actor_id,
+      workspace_id,
+      type,
+      title,
+      body,
+      link_path,
+      metadata
+    ) values (
+      new.assignee_id,
+      v_actor_id,
+      new.workspace_id,
+      'task_status_changed',
+      '담당 업무 상태가 변경되었습니다.',
+      new.title,
+      v_link_path,
+      jsonb_build_object('taskId', new.id, 'status', new.status)
+    );
+  end if;
+
+  return new;
+end;
+$$;
+
+revoke all on function private.create_task_assignee_notification() from public;
+
+create trigger create_task_assignee_notification
+after insert or update of assignee_id, status on public.tasks
+for each row
+execute function private.create_task_assignee_notification();
+
+-- 수신자 전용 RLS가 Realtime 변경 이벤트에도 적용되도록 publication에 포함한다.
+do $$
+begin
+  if not exists (
+    select 1
+    from pg_publication_tables
+    where pubname = 'supabase_realtime'
+      and schemaname = 'public'
+      and tablename = 'notifications'
+  ) then
+    alter publication supabase_realtime add table public.notifications;
+  end if;
+end;
+$$;
diff --git a/supabase/migrations/20260716040000_fix_notification_trigger_permissions.sql b/supabase/migrations/20260716040000_fix_notification_trigger_permissions.sql
new file mode 100644
index 0000000..6d04198
--- /dev/null
+++ b/supabase/migrations/20260716040000_fix_notification_trigger_permissions.sql
@@ -0,0 +1,116 @@
+-- 이미 적용된 알림 마이그레이션에서 트리거가 notifications에 쓸 수 있도록 권한을 보정한다.
+-- 앱 사용자는 직접 알림을 만들 수 없고, 공지·업무 변경 트리거만 제한적으로 생성한다.
+
+create or replace function private.create_announcement_notifications()
+returns trigger
+language plpgsql
+security definer
+set search_path = ''
+as $$
+begin
+  insert into public.notifications (
+    recipient_id,
+    actor_id,
+    workspace_id,
+    type,
+    title,
+    body,
+    link_path,
+    metadata
+  )
+  select
+    member.user_id,
+    new.author_id,
+    new.workspace_id,
+    'announcement_created',
+    '새 공지가 등록되었습니다.',
+    new.title,
+    format('/workspaces/%s/notices', new.workspace_id),
+    jsonb_build_object('announcementId', new.id)
+  from public.workspace_members as member
+  where member.workspace_id = new.workspace_id
+    and member.user_id is distinct from new.author_id;
+
+  return new;
+end;
+$$;
+
+revoke all on function private.create_announcement_notifications() from public;
+
+create or replace function private.create_task_assignee_notification()
+returns trigger
+language plpgsql
+security definer
+set search_path = ''
+as $$
+declare
+  v_actor_id uuid := auth.uid();
+  v_link_path text;
+begin
+  select case workspace.purpose
+    when 'side_project' then format('/workspaces/%s/sprint-board', new.workspace_id)
+    when 'team_project' then format('/workspaces/%s/project-management', new.workspace_id)
+    else format('/workspaces/%s/dashboard', new.workspace_id)
+  end
+  into v_link_path
+  from public.workspaces as workspace
+  where workspace.id = new.workspace_id;
+
+  if new.assignee_id is null
+    or new.assignee_id = v_actor_id
+    or not exists (
+      select 1
+      from public.workspace_members as member
+      where member.workspace_id = new.workspace_id
+        and member.user_id = new.assignee_id
+    ) then
+    return new;
+  end if;
+
+  if tg_op = 'INSERT' or new.assignee_id is distinct from old.assignee_id then
+    insert into public.notifications (
+      recipient_id,
+      actor_id,
+      workspace_id,
+      type,
+      title,
+      body,
+      link_path,
+      metadata
+    ) values (
+      new.assignee_id,
+      v_actor_id,
+      new.workspace_id,
+      'task_assigned',
+      '새 업무가 배정되었습니다.',
+      new.title,
+      v_link_path,
+      jsonb_build_object('taskId', new.id)
+    );
+  elsif new.status is distinct from old.status then
+    insert into public.notifications (
+      recipient_id,
+      actor_id,
+      workspace_id,
+      type,
+      title,
+      body,
+      link_path,
+      metadata
+    ) values (
+      new.assignee_id,
+      v_actor_id,
+      new.workspace_id,
+      'task_status_changed',
+      '담당 업무 상태가 변경되었습니다.',
+      new.title,
+      v_link_path,
+      jsonb_build_object('taskId', new.id, 'status', new.status)
+    );
+  end if;
+
+  return new;
+end;
+$$;
+
+revoke all on function private.create_task_assignee_notification() from public;