diff --git a/app.vue b/app.vue
index 8f62b8b..58ae2b5 100644
--- a/app.vue
+++ b/app.vue
@@ -1,3 +1,6 @@
 <template>
-  <NuxtPage />
+  <div>
+    <NuxtPage />
+    <ToastContainer />
+  </div>
 </template>
diff --git a/backend/api/admin/bulk-register.post.ts b/backend/api/admin/bulk-register.post.ts
index 1edf5a0..04cea5f 100644
--- a/backend/api/admin/bulk-register.post.ts
+++ b/backend/api/admin/bulk-register.post.ts
@@ -1,6 +1,5 @@
 import { query, execute, queryOne } from '../../utils/db'
-
-const ADMIN_EMAIL = 'coziny@gmail.com'
+import { requireAdmin } from '../../utils/session'
 
 interface TaskInput {
   description: string
@@ -31,22 +30,15 @@ interface ReportInput {
  */
 export default defineEventHandler(async (event) => {
   // 관리자 권한 체크
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAdmin(event)
   
   const clientIp = getHeader(event, 'x-forwarded-for') || 'unknown'
   
-  const currentUser = await query<any>(`
+  // 관리자 이메일 조회
+  const currentUser = await queryOne<any>(`
     SELECT employee_email FROM wr_employee_info WHERE employee_id = $1
   `, [userId])
-  
-  if (!currentUser[0] || currentUser[0].employee_email !== ADMIN_EMAIL) {
-    throw createError({ statusCode: 403, message: '관리자만 사용할 수 있습니다.' })
-  }
-  
-  const adminEmail = currentUser[0].employee_email
+  const adminEmail = currentUser?.employee_email || ''
   
   const body = await readBody<{
     reportYear: number
diff --git a/backend/api/admin/parse-image.post.ts b/backend/api/admin/parse-image.post.ts
index a5f31b0..0311cec 100644
--- a/backend/api/admin/parse-image.post.ts
+++ b/backend/api/admin/parse-image.post.ts
@@ -1,7 +1,6 @@
 import { query } from '../../utils/db'
 import { callOpenAIVision, REPORT_PARSE_SYSTEM_PROMPT } from '../../utils/openai'
-
-const ADMIN_EMAIL = 'coziny@gmail.com'
+import { requireAdmin } from '../../utils/session'
 
 interface ParsedTask {
   description: string
@@ -37,18 +36,7 @@ interface ParsedResult {
  */
 export default defineEventHandler(async (event) => {
   // 관리자 권한 체크
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
-  
-  const currentUser = await query<any>(`
-    SELECT employee_email FROM wr_employee_info WHERE employee_id = $1
-  `, [userId])
-  
-  if (!currentUser[0] || currentUser[0].employee_email !== ADMIN_EMAIL) {
-    throw createError({ statusCode: 403, message: '관리자만 사용할 수 있습니다.' })
-  }
+  await requireAdmin(event)
   
   const body = await readBody<{ images: string[] }>(event)
   
diff --git a/backend/api/admin/parse-report.post.ts b/backend/api/admin/parse-report.post.ts
index 1de98af..22453f2 100644
--- a/backend/api/admin/parse-report.post.ts
+++ b/backend/api/admin/parse-report.post.ts
@@ -1,7 +1,6 @@
 import { query } from '../../utils/db'
 import { callOpenAI, buildParseReportPrompt } from '../../utils/openai'
-
-const ADMIN_EMAIL = 'coziny@gmail.com'
+import { requireAdmin } from '../../utils/session'
 
 interface ParsedTask {
   description: string
@@ -37,18 +36,7 @@ interface ParsedResult {
  */
 export default defineEventHandler(async (event) => {
   // 관리자 권한 체크
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
-  
-  const currentUser = await query<any>(`
-    SELECT employee_email FROM wr_employee_info WHERE employee_id = $1
-  `, [userId])
-  
-  if (!currentUser[0] || currentUser[0].employee_email !== ADMIN_EMAIL) {
-    throw createError({ statusCode: 403, message: '관리자만 사용할 수 있습니다.' })
-  }
+  await requireAdmin(event)
   
   const body = await readBody<{ rawText: string }>(event)
   
diff --git a/backend/api/ai/parse-my-report-image.post.ts b/backend/api/ai/parse-my-report-image.post.ts
index 3c93e02..72f64ef 100644
--- a/backend/api/ai/parse-my-report-image.post.ts
+++ b/backend/api/ai/parse-my-report-image.post.ts
@@ -1,15 +1,13 @@
 import { query } from '../../utils/db'
 import { callOpenAIVision } from '../../utils/openai'
+import { requireAuth } from '../../utils/session'
 
 /**
  * 개인 주간보고 이미지 분석 (OpenAI Vision)
  * POST /api/ai/parse-my-report-image
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const body = await readBody<{ images: string[] }>(event)
   
diff --git a/backend/api/ai/parse-my-report.post.ts b/backend/api/ai/parse-my-report.post.ts
index c975246..58b4e5c 100644
--- a/backend/api/ai/parse-my-report.post.ts
+++ b/backend/api/ai/parse-my-report.post.ts
@@ -1,5 +1,6 @@
 import { query } from '../../utils/db'
 import { callOpenAI } from '../../utils/openai'
+import { requireAuth } from '../../utils/session'
 
 interface ParsedTask {
   description: string
@@ -26,10 +27,7 @@ interface ParsedResult {
  * POST /api/ai/parse-my-report
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const body = await readBody<{ rawText: string }>(event)
   
diff --git a/backend/api/dashboard/stats.get.ts b/backend/api/dashboard/stats.get.ts
index ff6d669..f385ff7 100644
--- a/backend/api/dashboard/stats.get.ts
+++ b/backend/api/dashboard/stats.get.ts
@@ -1,4 +1,5 @@
 import { query } from '../../utils/db'
+import { requireAuth } from '../../utils/session'
 
 /**
  * 대시보드 통계 API
@@ -9,10 +10,7 @@ import { query } from '../../utils/db'
  * - 제출 현황
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const q = getQuery(event)
   const year = parseInt(q.year as string) || new Date().getFullYear()
diff --git a/backend/api/employee/[id]/detail.get.ts b/backend/api/employee/[id]/detail.get.ts
index 746d545..fcd7187 100644
--- a/backend/api/employee/[id]/detail.get.ts
+++ b/backend/api/employee/[id]/detail.get.ts
@@ -1,12 +1,19 @@
 import { queryOne, query } from '../../../utils/db'
+import { requireAuth, getSessionIdFromCookie, getDbSession } from '../../../utils/session'
 
 /**
  * 직원 상세 조회
  * GET /api/employee/[id]/detail
  */
 export default defineEventHandler(async (event) => {
+  await requireAuth(event)
+  
   const employeeId = getRouterParam(event, 'id')
-  const currentHistoryId = getCookie(event, 'login_history_id')
+  
+  // 세션에서 현재 로그인 히스토리 ID 가져오기
+  const sessionId = getSessionIdFromCookie(event)
+  const session = sessionId ? await getDbSession(sessionId) : null
+  const currentHistoryId = session?.loginHistoryId || null
   
   const employee = await queryOne<any>(`
     SELECT * FROM wr_employee_info WHERE employee_id = $1
diff --git a/backend/api/feedback/[id]/delete.delete.ts b/backend/api/feedback/[id]/delete.delete.ts
index 3320d4d..ee89253 100644
--- a/backend/api/feedback/[id]/delete.delete.ts
+++ b/backend/api/feedback/[id]/delete.delete.ts
@@ -1,14 +1,12 @@
 import { query, execute } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 
 /**
  * 개선의견 삭제
  * DELETE /api/feedback/[id]/delete
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const feedbackId = getRouterParam(event, 'id')
   if (!feedbackId) {
@@ -24,7 +22,7 @@ export default defineEventHandler(async (event) => {
     throw createError({ statusCode: 404, message: '의견을 찾을 수 없습니다.' })
   }
   
-  if (feedback[0].author_id !== parseInt(userId)) {
+  if (feedback[0].author_id !== userId) {
     throw createError({ statusCode: 403, message: '본인의 의견만 삭제할 수 있습니다.' })
   }
   
diff --git a/backend/api/feedback/[id]/like.post.ts b/backend/api/feedback/[id]/like.post.ts
index 2416693..7cafa20 100644
--- a/backend/api/feedback/[id]/like.post.ts
+++ b/backend/api/feedback/[id]/like.post.ts
@@ -1,14 +1,12 @@
 import { query, execute, queryOne } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 
 /**
  * 개선의견 공감 토글
  * POST /api/feedback/[id]/like
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const feedbackId = getRouterParam(event, 'id')
   if (!feedbackId) {
diff --git a/backend/api/feedback/[id]/update.put.ts b/backend/api/feedback/[id]/update.put.ts
index f7fee2a..c860cbc 100644
--- a/backend/api/feedback/[id]/update.put.ts
+++ b/backend/api/feedback/[id]/update.put.ts
@@ -1,14 +1,12 @@
 import { query, execute } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 
 /**
  * 개선의견 수정
  * PUT /api/feedback/[id]/update
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const feedbackId = getRouterParam(event, 'id')
   if (!feedbackId) {
@@ -24,7 +22,7 @@ export default defineEventHandler(async (event) => {
     throw createError({ statusCode: 404, message: '의견을 찾을 수 없습니다.' })
   }
   
-  if (feedback[0].author_id !== parseInt(userId)) {
+  if (feedback[0].author_id !== userId) {
     throw createError({ statusCode: 403, message: '본인의 의견만 수정할 수 있습니다.' })
   }
   
diff --git a/backend/api/feedback/create.post.ts b/backend/api/feedback/create.post.ts
index 787a571..63bc7e1 100644
--- a/backend/api/feedback/create.post.ts
+++ b/backend/api/feedback/create.post.ts
@@ -1,14 +1,12 @@
 import { query, queryOne } from '../../utils/db'
+import { requireAuth } from '../../utils/session'
 
 /**
  * 개선의견 작성
  * POST /api/feedback/create
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const body = await readBody<{
     category: string
diff --git a/backend/api/feedback/list.get.ts b/backend/api/feedback/list.get.ts
index 2b68b2d..42613d8 100644
--- a/backend/api/feedback/list.get.ts
+++ b/backend/api/feedback/list.get.ts
@@ -1,14 +1,12 @@
 import { query } from '../../utils/db'
+import { requireAuth } from '../../utils/session'
 
 /**
  * 개선의견 목록 조회
  * GET /api/feedback/list
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const q = getQuery(event)
   const page = parseInt(q.page as string) || 1
@@ -91,7 +89,7 @@ export default defineEventHandler(async (event) => {
       createdAt: f.created_at,
       updatedAt: f.updated_at,
       isLiked: f.is_liked,
-      isOwner: f.author_id === parseInt(userId)
+      isOwner: f.author_id === userId
     })),
     pagination: {
       page,
diff --git a/backend/api/project/my-projects.get.ts b/backend/api/project/my-projects.get.ts
index b837d48..4cff9ed 100644
--- a/backend/api/project/my-projects.get.ts
+++ b/backend/api/project/my-projects.get.ts
@@ -1,14 +1,12 @@
 import { query } from '../../utils/db'
+import { requireAuth } from '../../utils/session'
 
 /**
  * 내가 보고서 작성한 프로젝트 목록
  * GET /api/project/my-projects
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   // 내가 주간보고를 작성한 프로젝트 + 전체 활성 프로젝트
   const projects = await query(`
@@ -23,7 +21,7 @@ export default defineEventHandler(async (event) => {
     ) t ON p.project_id = t.project_id
     WHERE p.project_status = 'ACTIVE'
     ORDER BY has_my_report DESC, p.project_name
-  `, [parseInt(userId)])
+  `, [userId])
   
   return projects.map((p: any) => ({
     projectId: p.project_id,
diff --git a/backend/api/report/summary/[id]/review.put.ts b/backend/api/report/summary/[id]/review.put.ts
index a855fbf..b06cdb1 100644
--- a/backend/api/report/summary/[id]/review.put.ts
+++ b/backend/api/report/summary/[id]/review.put.ts
@@ -1,4 +1,5 @@
 import { execute, queryOne } from '../../../../utils/db'
+import { requireAuth } from '../../../../utils/session'
 
 interface ReviewBody {
   reviewerComment?: string
@@ -9,10 +10,7 @@ interface ReviewBody {
  * PUT /api/report/summary/[id]/review
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const summaryId = getRouterParam(event, 'id')
   const body = await readBody<ReviewBody>(event)
@@ -33,7 +31,7 @@ export default defineEventHandler(async (event) => {
       summary_status = 'REVIEWED',
       updated_at = NOW()
     WHERE summary_id = $3
-  `, [parseInt(userId), body.reviewerComment || null, summaryId])
+  `, [userId, body.reviewerComment || null, summaryId])
   
   return { success: true }
 })
diff --git a/backend/api/report/summary/aggregate.post.ts b/backend/api/report/summary/aggregate.post.ts
index e829945..e3422d0 100644
--- a/backend/api/report/summary/aggregate.post.ts
+++ b/backend/api/report/summary/aggregate.post.ts
@@ -1,7 +1,8 @@
-import { defineEventHandler, readBody, createError, getCookie } from 'h3'
+import { defineEventHandler, readBody, createError } from 'h3'
 import { query, queryOne, execute, insertReturning } from '../../../utils/db'
 import { getClientIp } from '../../../utils/ip'
 import { getCurrentUserEmail } from '../../../utils/user'
+import { requireAuth } from '../../../utils/session'
 import OpenAI from 'openai'
 
 interface AggregateBody {
@@ -19,10 +20,7 @@ const openai = new OpenAI({
  * POST /api/report/summary/aggregate
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const body = await readBody<AggregateBody>(event)
   const clientIp = getClientIp(event)
diff --git a/backend/api/report/summary/available-projects.get.ts b/backend/api/report/summary/available-projects.get.ts
index 37cf0f6..24fc920 100644
--- a/backend/api/report/summary/available-projects.get.ts
+++ b/backend/api/report/summary/available-projects.get.ts
@@ -1,12 +1,9 @@
-import { defineEventHandler, getQuery, createError, getCookie } from 'h3'
+import { defineEventHandler, getQuery, createError } from 'h3'
 import { query } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const { year, week } = getQuery(event)
   
diff --git a/backend/api/report/summary/regenerate-ai.post.ts b/backend/api/report/summary/regenerate-ai.post.ts
index 106cd2c..0e7f76c 100644
--- a/backend/api/report/summary/regenerate-ai.post.ts
+++ b/backend/api/report/summary/regenerate-ai.post.ts
@@ -1,5 +1,6 @@
-import { defineEventHandler, createError, getCookie } from 'h3'
+import { defineEventHandler, createError } from 'h3'
 import { query, queryOne, execute } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 import OpenAI from 'openai'
 
 const openai = new OpenAI({
@@ -11,10 +12,7 @@ const openai = new OpenAI({
  * POST /api/report/summary/regenerate-ai
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   // AI 요약이 없는 취합 보고서 조회
   const summaries = await query<any>(`
diff --git a/backend/api/report/weekly/[id]/delete.delete.ts b/backend/api/report/weekly/[id]/delete.delete.ts
index 6793ffb..cf514c5 100644
--- a/backend/api/report/weekly/[id]/delete.delete.ts
+++ b/backend/api/report/weekly/[id]/delete.delete.ts
@@ -1,4 +1,5 @@
 import { query, execute } from '../../../../utils/db'
+import { requireAuth } from '../../../../utils/session'
 
 const ADMIN_EMAIL = 'coziny@gmail.com'
 
@@ -7,10 +8,7 @@ const ADMIN_EMAIL = 'coziny@gmail.com'
  * DELETE /api/report/weekly/[id]/delete
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const reportId = getRouterParam(event, 'id')
   if (!reportId) {
@@ -33,7 +31,7 @@ export default defineEventHandler(async (event) => {
   }
   
   // 권한 체크: 본인 또는 관리자만 삭제 가능
-  if (report[0].author_id !== parseInt(userId) && !isAdmin) {
+  if (report[0].author_id !== userId && !isAdmin) {
     throw createError({ statusCode: 403, message: '삭제 권한이 없습니다.' })
   }
   
diff --git a/backend/api/report/weekly/[id]/detail.get.ts b/backend/api/report/weekly/[id]/detail.get.ts
index 0d6db36..83024ef 100644
--- a/backend/api/report/weekly/[id]/detail.get.ts
+++ b/backend/api/report/weekly/[id]/detail.get.ts
@@ -1,14 +1,12 @@
 import { query, queryOne } from '../../../../utils/db'
+import { requireAuth } from '../../../../utils/session'
 
 /**
  * 주간보고 상세 조회
  * GET /api/report/weekly/[id]/detail
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const reportId = getRouterParam(event, 'id')
   
diff --git a/backend/api/report/weekly/[id]/submit.post.ts b/backend/api/report/weekly/[id]/submit.post.ts
index b8d7fe8..72161e1 100644
--- a/backend/api/report/weekly/[id]/submit.post.ts
+++ b/backend/api/report/weekly/[id]/submit.post.ts
@@ -1,16 +1,14 @@
 import { execute, queryOne } from '../../../../utils/db'
 import { getClientIp } from '../../../../utils/ip'
 import { getCurrentUserEmail } from '../../../../utils/user'
+import { requireAuth } from '../../../../utils/session'
 
 /**
  * 주간보고 제출
  * POST /api/report/weekly/[id]/submit
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const reportId = getRouterParam(event, 'id')
   const clientIp = getClientIp(event)
@@ -25,7 +23,7 @@ export default defineEventHandler(async (event) => {
     throw createError({ statusCode: 404, message: '보고서를 찾을 수 없습니다.' })
   }
   
-  if (report.author_id !== parseInt(userId)) {
+  if (report.author_id !== userId) {
     throw createError({ statusCode: 403, message: '본인의 보고서만 제출할 수 있습니다.' })
   }
   
diff --git a/backend/api/report/weekly/[id]/update.put.ts b/backend/api/report/weekly/[id]/update.put.ts
index c562da2..0a82ebf 100644
--- a/backend/api/report/weekly/[id]/update.put.ts
+++ b/backend/api/report/weekly/[id]/update.put.ts
@@ -1,4 +1,5 @@
 import { query, execute, queryOne } from '../../../../utils/db'
+import { requireAuth } from '../../../../utils/session'
 
 const ADMIN_EMAIL = 'coziny@gmail.com'
 
@@ -7,10 +8,7 @@ const ADMIN_EMAIL = 'coziny@gmail.com'
  * PUT /api/report/weekly/[id]/update
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const reportId = getRouterParam(event, 'id')
   const clientIp = getHeader(event, 'x-forwarded-for') || 'unknown'
@@ -28,7 +26,7 @@ export default defineEventHandler(async (event) => {
   }
   
   // 관리자가 아니면 본인 보고서만 수정 가능
-  if (!isAdmin && report.author_id !== parseInt(userId)) {
+  if (!isAdmin && report.author_id !== userId) {
     throw createError({ statusCode: 403, message: '본인의 보고서만 수정할 수 있습니다.' })
   }
   
diff --git a/backend/api/report/weekly/create.post.ts b/backend/api/report/weekly/create.post.ts
index ac5caf1..58d7a9e 100644
--- a/backend/api/report/weekly/create.post.ts
+++ b/backend/api/report/weekly/create.post.ts
@@ -1,14 +1,13 @@
 import { query, execute, queryOne } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 
 /**
  * 주간보고 작성
  * POST /api/report/weekly/create
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  // 세션 기반 인증 사용 (레거시 쿠키 대신)
+  const userId = await requireAuth(event)
   
   const clientIp = getHeader(event, 'x-forwarded-for') || 'unknown'
   const user = await queryOne<any>(`SELECT employee_email FROM wr_employee_info WHERE employee_id = $1`, [userId])
diff --git a/backend/api/report/weekly/current-week.get.ts b/backend/api/report/weekly/current-week.get.ts
index 60934d3..265f414 100644
--- a/backend/api/report/weekly/current-week.get.ts
+++ b/backend/api/report/weekly/current-week.get.ts
@@ -1,15 +1,13 @@
 import { query } from '../../../utils/db'
 import { getWeekInfo, formatWeekString } from '../../../utils/week-calc'
+import { requireAuth } from '../../../utils/session'
 
 /**
  * 이번 주 보고서 현황 조회
  * GET /api/report/weekly/current-week
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  const userId = await requireAuth(event)
   
   const weekInfo = getWeekInfo()
   
@@ -20,7 +18,7 @@ export default defineEventHandler(async (event) => {
     JOIN wr_project_info p ON r.project_id = p.project_id
     WHERE r.author_id = $1 AND r.report_year = $2 AND r.report_week = $3
     ORDER BY p.project_name
-  `, [parseInt(userId), weekInfo.year, weekInfo.week])
+  `, [userId, weekInfo.year, weekInfo.week])
   
   return {
     weekInfo: {
diff --git a/backend/api/report/weekly/list.get.ts b/backend/api/report/weekly/list.get.ts
index 66e1443..508528a 100644
--- a/backend/api/report/weekly/list.get.ts
+++ b/backend/api/report/weekly/list.get.ts
@@ -1,4 +1,5 @@
 import { query } from '../../../utils/db'
+import { requireAuth } from '../../../utils/session'
 
 const ADMIN_EMAIL = 'coziny@gmail.com'
 
@@ -19,10 +20,8 @@ const ADMIN_EMAIL = 'coziny@gmail.com'
  * - limit: 조회 개수 (기본 100)
  */
 export default defineEventHandler(async (event) => {
-  const userId = getCookie(event, 'user_id')
-  if (!userId) {
-    throw createError({ statusCode: 401, message: '로그인이 필요합니다.' })
-  }
+  // 세션 기반 인증 사용
+  const userId = await requireAuth(event)
   
   // 현재 사용자 정보 조회 (관리자 여부 확인)
   const currentUser = await query<any>(`
diff --git a/backend/utils/user.ts b/backend/utils/user.ts
index 9a09c36..4223164 100644
--- a/backend/utils/user.ts
+++ b/backend/utils/user.ts
@@ -1,16 +1,17 @@
 import type { H3Event } from 'h3'
 import { queryOne } from './db'
+import { getAuthenticatedUserId } from './session'
 
 /**
  * 현재 로그인한 사용자의 이메일 조회
  */
 export async function getCurrentUserEmail(event: H3Event): Promise<string | null> {
-  const userId = getCookie(event, 'user_id')
+  const userId = await getAuthenticatedUserId(event)
   if (!userId) return null
   
   const user = await queryOne<{ employee_email: string }>(`
     SELECT employee_email FROM wr_employee_info WHERE employee_id = $1
-  `, [parseInt(userId)])
+  `, [userId])
   
   return user?.employee_email || null
 }
diff --git a/frontend/components/common/ToastContainer.vue b/frontend/components/common/ToastContainer.vue
new file mode 100644
index 0000000..699c5df
--- /dev/null
+++ b/frontend/components/common/ToastContainer.vue
@@ -0,0 +1,49 @@
+<template>
+  <div class="toast-container position-fixed top-0 end-0 p-3" style="z-index: 1100;">
+    <div 
+      v-for="toast in toasts" 
+      :key="toast.id"
+      class="toast show"
+      role="alert"
+    >
+      <div class="toast-header" :class="headerClass(toast.type)">
+        <i :class="iconClass(toast.type)" class="me-2"></i>
+        <strong class="me-auto">{{ toast.title }}</strong>
+        <button type="button" class="btn-close btn-close-white" @click="remove(toast.id)"></button>
+      </div>
+      <div class="toast-body">
+        {{ toast.message }}
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+const { toasts, remove } = useToast()
+
+function headerClass(type: string) {
+  const classes: Record<string, string> = {
+    success: 'bg-success text-white',
+    error: 'bg-danger text-white',
+    warning: 'bg-warning text-dark',
+    info: 'bg-primary text-white'
+  }
+  return classes[type] || classes.info
+}
+
+function iconClass(type: string) {
+  const icons: Record<string, string> = {
+    success: 'bi bi-check-circle-fill',
+    error: 'bi bi-x-circle-fill',
+    warning: 'bi bi-exclamation-triangle-fill',
+    info: 'bi bi-info-circle-fill'
+  }
+  return icons[type] || icons.info
+}
+</script>
+
+<style scoped>
+.toast {
+  min-width: 300px;
+}
+</style>
diff --git a/frontend/components/layout/AppHeader.vue b/frontend/components/layout/AppHeader.vue
index 551d43a..de593fe 100644
--- a/frontend/components/layout/AppHeader.vue
+++ b/frontend/components/layout/AppHeader.vue
@@ -3,7 +3,7 @@
     <div class="container-fluid">
       <NuxtLink class="navbar-brand" to="/">
         <i class="bi bi-clipboard-check me-2"></i>
-        주간업무보고
+        업무관리프로그램
       </NuxtLink>
 
       <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav">
diff --git a/frontend/composables/useToast.ts b/frontend/composables/useToast.ts
new file mode 100644
index 0000000..c690af0
--- /dev/null
+++ b/frontend/composables/useToast.ts
@@ -0,0 +1,60 @@
+/**
+ * Bootstrap Toast Composable
+ * 전역 토스트 메시지 관리
+ */
+interface ToastMessage {
+  id: number
+  type: 'success' | 'error' | 'warning' | 'info'
+  title?: string
+  message: string
+  duration?: number
+}
+
+const toasts = ref<ToastMessage[]>([])
+let toastId = 0
+
+export function useToast() {
+  function show(message: string, type: ToastMessage['type'] = 'info', title?: string, duration = 3000) {
+    const id = ++toastId
+    toasts.value.push({ id, type, title, message, duration })
+    
+    if (duration > 0) {
+      setTimeout(() => {
+        remove(id)
+      }, duration)
+    }
+  }
+  
+  function success(message: string, title?: string, duration = 3000) {
+    show(message, 'success', title || '성공', duration)
+  }
+  
+  function error(message: string, title?: string, duration = 5000) {
+    show(message, 'error', title || '오류', duration)
+  }
+  
+  function warning(message: string, title?: string, duration = 4000) {
+    show(message, 'warning', title || '경고', duration)
+  }
+  
+  function info(message: string, title?: string, duration = 3000) {
+    show(message, 'info', title || '알림', duration)
+  }
+  
+  function remove(id: number) {
+    const idx = toasts.value.findIndex(t => t.id === id)
+    if (idx > -1) {
+      toasts.value.splice(idx, 1)
+    }
+  }
+  
+  return {
+    toasts,
+    show,
+    success,
+    error,
+    warning,
+    info,
+    remove
+  }
+}
diff --git a/frontend/report/weekly/write.vue b/frontend/report/weekly/write.vue
index 92c7ce8..a577b39 100644
--- a/frontend/report/weekly/write.vue
+++ b/frontend/report/weekly/write.vue
@@ -457,6 +457,7 @@ const { fetchCurrentUser } = useAuth()
 const route = useRoute()
 const { getWeekInfo, getWeekDates, getLastWeekInfo, getActualCurrentWeekInfo, getMonday, changeWeek: calcChangeWeek } = useWeekCalc()
 const router = useRouter()
+const toast = useToast()
 
 interface TaskItem {
   projectId: number
@@ -656,7 +657,7 @@ async function setDefaultWeek(userId: number) {
     const isFutureWeek = year > currentWeek.year || (year === currentWeek.year && week > currentWeek.week)
     
     if (isFutureWeek) {
-      alert('작성할 수 없는 주차입니다.')
+      toast.warning('작성할 수 없는 주차입니다.')
       router.replace('/report/weekly')
       return false
     }
@@ -860,7 +861,7 @@ function formatHoursDisplay(hours: number): string {
 async function handleSubmit() {
   const validTasks = form.value.tasks.filter(t => t.description.trim())
   if (validTasks.length === 0) {
-    alert('최소 1개 이상의 Task를 입력해주세요.')
+    toast.warning('최소 1개 이상의 Task를 입력해주세요.')
     return
   }
   
@@ -885,10 +886,10 @@ async function handleSubmit() {
         remarkDescription: form.value.remarkDescription
       }
     })
-    alert('주간보고가 작성되었습니다.')
+    toast.success('주간보고가 작성되었습니다.')
     router.push('/report/weekly')
   } catch (e: any) {
-    alert(e.data?.message || '저장에 실패했습니다.')
+    toast.error(e.data?.message || '저장에 실패했습니다.')
   } finally {
     isSaving.value = false
   }
@@ -1000,11 +1001,11 @@ async function runAiParse() {
       }
       aiStep.value = 'matching'
     } else {
-      alert('분석된 내용이 없습니다.')
+      toast.warning('분석된 내용이 없습니다.')
     }
   } catch (e: any) {
     console.error('=== AI 분석 에러 ===', e)
-    alert(e.data?.message || 'AI 분석에 실패했습니다.')
+    toast.error(e.data?.message || 'AI 분석에 실패했습니다.')
   } finally {
     isAiParsing.value = false
   }