diff --git a/app.py b/app.py
index ad16006..fd8b799 100644
--- a/app.py
+++ b/app.py
@@ -1,8 +1,4 @@
-import os
-import io
-import random
-import requests
-import openpyxl
+import os, io, random, requests, openpyxl
 from flask import Flask, render_template, request, jsonify, send_file
 
 app = Flask(__name__)
@@ -13,13 +9,20 @@ os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)
 YONGSAN_CENTER = (37.5326, 126.9906)
 
 store = {
-    'workers': [],
-    'workplaces': [],
-    'assignments': {},
+    'tabs': {},
+    'active_tab': None,
+    'next_id': 0,
     'filename': None,
 }
 
 
+def tab_data(tab_id):
+    t = store['tabs'].get(tab_id)
+    if not t:
+        return None, 404
+    return t, None
+
+
 def geocode(address):
     try:
         url = 'https://nominatim.openstreetmap.org/search'
@@ -48,25 +51,105 @@ def geocode_with_fallback(address):
     return YONGSAN_CENTER[0] + jitter, YONGSAN_CENTER[1] + jitter
 
 
-@app.route('/')
-def index():
-    return render_template('index.html')
+def empty_tab(name):
+    return {'name': name, 'workers': [], 'workplaces': [], 'assignments': {}}
 
 
-@app.route('/upload', methods=['POST'])
+# ── Tab management ──
+
+@app.route('/api/tabs')
+def list_tabs():
+    tabs = [{'id': tid, 'name': t['name'],
+             'workerCount': len(t['workers']),
+             'assignCount': len(t['assignments'])}
+            for tid, t in store['tabs'].items()]
+    return jsonify({'tabs': tabs, 'activeTab': store['active_tab']})
+
+
+@app.route('/api/tabs/add', methods=['POST'])
+def add_tab():
+    body = request.get_json() or {}
+    name = (body.get('name') or '').strip() or f'탭 {store["next_id"] + 1}'
+    tid = f'tab_{store["next_id"]}'
+    store['next_id'] += 1
+    store['tabs'][tid] = empty_tab(name)
+    if store['active_tab'] is None:
+        store['active_tab'] = tid
+    return jsonify({'id': tid, 'name': name})
+
+
+@app.route('/api/tabs/rename', methods=['POST'])
+def rename_tab():
+    body = request.get_json() or {}
+    tid = body.get('id')
+    name = (body.get('name') or '').strip()
+    if not tid or not name or tid not in store['tabs']:
+        return jsonify({'error': '잘못된 요청'}), 400
+    store['tabs'][tid]['name'] = name
+    return jsonify({'id': tid, 'name': name})
+
+
+@app.route('/api/tabs/delete', methods=['POST'])
+def delete_tab():
+    body = request.get_json() or {}
+    tid = body.get('id')
+    if not tid or tid not in store['tabs']:
+        return jsonify({'error': '잘못된 요청'}), 400
+    del store['tabs'][tid]
+    if store['active_tab'] == tid:
+        keys = list(store['tabs'].keys())
+        store['active_tab'] = keys[0] if keys else None
+    return jsonify({'deleted': tid})
+
+
+@app.route('/api/tabs/activate', methods=['POST'])
+def activate_tab():
+    body = request.get_json() or {}
+    tid = body.get('id')
+    if not tid or tid not in store['tabs']:
+        return jsonify({'error': '탭을 찾을 수 없음'}), 400
+    store['active_tab'] = tid
+    return jsonify({'activeTab': tid})
+
+
+# ── Data ──
+
+def get_active():
+    t = store['tabs'].get(store['active_tab'])
+    if not t:
+        return None, jsonify({'error': '탭 없음'}), 400
+    return t, None, None
+
+
+@app.route('/api/data')
+def get_data():
+    tid = request.args.get('tab') or store['active_tab']
+    t = store['tabs'].get(tid)
+    if not t:
+        return jsonify({'workers': [], 'workplaces': [], 'assignments': {}})
+    return jsonify({
+        'workers': t['workers'],
+        'workplaces': t['workplaces'],
+        'assignments': t['assignments'],
+    })
+
+
+@app.route('/api/upload', methods=['POST'])
 def upload():
+    tid = request.form.get('tab') or store['active_tab']
+    t = store['tabs'].get(tid)
+    if not t:
+        return jsonify({'error': '탭 없음'}), 400
+
     file = request.files.get('file')
     if not file:
         return jsonify({'error': '파일이 없습니다.'}), 400
 
     path = os.path.join(app.config['UPLOAD_FOLDER'], file.filename)
     file.save(path)
-
     wb = openpyxl.load_workbook(path, data_only=True)
 
-    workers = []
-    workplaces = []
-
+    workers, workplaces = [], []
     for sheet_name in wb.sheetnames:
         ws = wb[sheet_name]
         headers = [str(c.value or '').strip() for c in ws[1]]
@@ -77,22 +160,17 @@ def upload():
                 if not any(row):
                     continue
                 name = str(row[idx.get('이름', 0)] or '').strip()
-                hope = str(row[idx.get('희망사항', 1)] or '').strip()
-                addr = str(row[idx.get('주소', 2)] or '').strip()
-                dob = str(row[idx.get('생년월일', 3)] or '').strip()
-                phone = str(row[idx.get('연락처', 4)] or '').strip()
                 if not name:
                     continue
-                lat, lng = geocode_with_fallback(addr)
+                lat, lng = geocode_with_fallback(str(row[idx.get('주소', 2)] or '').strip())
                 workers.append({
                     'id': f'w{len(workers)}',
                     'name': name,
-                    'hope': hope,
-                    'address': addr,
-                    'dob': dob,
-                    'phone': phone,
-                    'lat': lat,
-                    'lng': lng,
+                    'hope': str(row[idx.get('희망사항', 1)] or '').strip(),
+                    'address': str(row[idx.get('주소', 2)] or '').strip(),
+                    'dob': str(row[idx.get('생년월일', 3)] or '').strip(),
+                    'phone': str(row[idx.get('연락처', 4)] or '').strip(),
+                    'lat': lat, 'lng': lng,
                 })
 
         if '희망사항' not in headers:
@@ -101,106 +179,100 @@ def upload():
                 if not any(row):
                     continue
                 name = str(row[idx.get('이름', 0)] or '').strip()
-                addr = str(row[idx.get('주소', 1)] or '').strip()
                 if not name:
                     continue
-                lat, lng = geocode_with_fallback(addr)
+                lat, lng = geocode_with_fallback(str(row[idx.get('주소', 1)] or '').strip())
                 workplaces.append({
                     'id': f'p{len(workplaces)}',
                     'name': name,
-                    'address': addr,
-                    'lat': lat,
-                    'lng': lng,
+                    'address': str(row[idx.get('주소', 1)] or '').strip(),
+                    'lat': lat, 'lng': lng,
                 })
 
-    store['workers'] = workers
-    store['workplaces'] = workplaces
-    store['assignments'] = {}
+    t['workers'] = workers
+    t['workplaces'] = workplaces
+    t['assignments'] = {}
     store['filename'] = file.filename
 
-    return jsonify({
-        'workers': workers,
-        'workplaces': workplaces,
-        'assignments': {},
-    })
+    return jsonify({'workers': workers, 'workplaces': workplaces, 'assignments': {}})
 
 
-@app.route('/data')
-def get_data():
-    return jsonify({
-        'workers': store['workers'],
-        'workplaces': store['workplaces'],
-        'assignments': store['assignments'],
-    })
-
-
-@app.route('/assign', methods=['POST'])
+@app.route('/api/assign', methods=['POST'])
 def assign():
-    body = request.get_json()
-    worker_id = body.get('workerId')
-    workplace_id = body.get('workplaceId')
+    body = request.get_json() or {}
+    tid = body.get('tab') or store['active_tab']
+    t = store['tabs'].get(tid)
+    if not t:
+        return jsonify({'error': '탭 없음'}), 400
+    worker_id, workplace_id = body.get('workerId'), body.get('workplaceId')
     if not worker_id or not workplace_id:
-        return jsonify({'error': '잘못된 요청입니다.'}), 400
-    store['assignments'][worker_id] = workplace_id
-    return jsonify({'assignments': store['assignments']})
+        return jsonify({'error': '잘못된 요청'}), 400
+    t['assignments'][worker_id] = workplace_id
+    return jsonify({'assignments': t['assignments']})
 
 
-@app.route('/unassign', methods=['POST'])
+@app.route('/api/unassign', methods=['POST'])
 def unassign():
-    body = request.get_json()
+    body = request.get_json() or {}
+    tid = body.get('tab') or store['active_tab']
+    t = store['tabs'].get(tid)
+    if not t:
+        return jsonify({'error': '탭 없음'}), 400
     worker_id = body.get('workerId')
-    store['assignments'].pop(worker_id, None)
-    return jsonify({'assignments': store['assignments']})
+    t['assignments'].pop(worker_id, None)
+    return jsonify({'assignments': t['assignments']})
 
 
-@app.route('/reset', methods=['POST'])
+@app.route('/api/reset', methods=['POST'])
 def reset():
-    store['assignments'] = {}
-    return jsonify({'assignments': {}})
+    body = request.get_json() or {}
+    tid = body.get('tab') or store['active_tab']
+    t = store['tabs'].get(tid)
+    if t:
+        t['assignments'] = {}
+    return jsonify({'assignments': t['assignments'] if t else {}})
 
 
-@app.route('/export')
+@app.route('/api/export')
 def export():
+    tid = request.args.get('tab') or store['active_tab']
+    t = store['tabs'].get(tid)
+    if not t:
+        return jsonify({'error': '탭 없음'}), 400
+
     wb = openpyxl.Workbook()
+
     ws1 = wb.active
     ws1.title = '배치 현황'
     ws1.append(['이름', '연락처', '생년월일', '희망사항', '주소', '배치근무지', '근무지주소'])
-
-    wp_lookup = {wp['id']: wp for wp in store['workplaces']}
-    for w in store['workers']:
-        assigned = store['assignments'].get(w['id'])
-        wp_name = ''
-        wp_addr = ''
-        if assigned and assigned in wp_lookup:
-            wp_name = wp_lookup[assigned]['name']
-            wp_addr = wp_lookup[assigned]['address']
-        ws1.append([w['name'], w['phone'], w['dob'], w['hope'], w['address'], wp_name, wp_addr])
+    wp_lookup = {wp['id']: wp for wp in t['workplaces']}
+    for w in t['workers']:
+        a_id = t['assignments'].get(w['id'])
+        wn = wp_lookup[a_id]['name'] if a_id and a_id in wp_lookup else ''
+        wa = wp_lookup[a_id]['address'] if a_id and a_id in wp_lookup else ''
+        ws1.append([w['name'], w['phone'], w['dob'], w['hope'], w['address'], wn, wa])
 
     ws2 = wb.create_sheet('근무지별 배치')
     ws2.append(['근무지명', '주소', '배치인원', '배치된근무자'])
-
-    for wp in store['workplaces']:
-        assigned_workers = [
-            w['name'] for w in store['workers']
-            if store['assignments'].get(w['id']) == wp['id']
-        ]
-        count = len(assigned_workers)
-        ws2.append([wp['name'], wp['address'], count, ', '.join(assigned_workers)])
+    for wp in t['workplaces']:
+        aw = [w['name'] for w in t['workers'] if t['assignments'].get(w['id']) == wp['id']]
+        ws2.append([wp['name'], wp['address'], len(aw), ', '.join(aw)])
 
     buf = io.BytesIO()
     wb.save(buf)
     buf.seek(0)
 
-    name = store.get('filename', 'export.xlsx')
-    base, ext = os.path.splitext(name)
-    download_name = f'{base}_배치결과{ext}'
+    tab_name = t['name']
+    fname = store.get('filename', 'export.xlsx')
+    base, ext = os.path.splitext(fname)
+    dn = f'{base}_{tab_name}_배치결과{ext}'
+    return send_file(buf, as_attachment=True, download_name=dn,
+                     mimetype='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet')
 
-    return send_file(
-        buf,
-        as_attachment=True,
-        download_name=download_name,
-        mimetype='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
-    )
+
+@app.route('/')
+def index():
+    return render_template('index.html')
 
 
 if __name__ == '__main__':
diff --git a/static/style.css b/static/style.css
index de42f09..31008f0 100644
--- a/static/style.css
+++ b/static/style.css
@@ -31,6 +31,39 @@ body { font-family: 'Segoe UI', 'Malgun Gothic', sans-serif; height: 100vh; over
 .status-badge.partial { background: #fef3c7; color: #d97706; }
 .status-badge.complete { background: #d1fae5; color: #059669; }
 
+#tabBar {
+  display: flex; align-items: center; background: #e8eaed; padding: 0 12px;
+  border-bottom: 1px solid #d0d0d0; min-height: 40px; gap: 2px; z-index: 999; flex-shrink: 0;
+}
+.tab-list { display: flex; align-items: stretch; flex: 1; overflow-x: auto; gap: 2px; }
+.tab-list::-webkit-scrollbar { height: 3px; }
+.tab-list::-webkit-scrollbar-thumb { background: #ccc; border-radius: 2px; }
+.tab-item {
+  display: flex; align-items: center; gap: 6px; padding: 6px 10px;
+  background: #dde0e3; border-radius: 6px 6px 0 0; cursor: pointer;
+  font-size: 13px; color: #555; white-space: nowrap; user-select: none;
+  transition: all 0.15s; min-width: 0;
+}
+.tab-item:hover { background: #d0d3d6; }
+.tab-item.active { background: #fff; color: #1a73e8; font-weight: 600; box-shadow: 0 -1px 2px rgba(0,0,0,0.06); }
+.tab-name { flex: 1; min-width: 30px; }
+.tab-name:hover { text-decoration: underline; }
+.tab-badge { font-size: 10px; color: #888; background: #f0f0f0; padding: 1px 6px; border-radius: 8px; }
+.tab-item.active .tab-badge { background: #e8f0fe; color: #1a73e8; }
+.tab-del { font-size: 16px; color: #999; line-height: 1; padding: 0 2px; }
+.tab-del:hover { color: #ef4444; }
+.tab-add {
+  flex-shrink: 0; width: 30px; height: 30px; border: none; background: transparent;
+  border-radius: 6px; cursor: pointer; color: #666; font-size: 16px;
+  display: flex; align-items: center; justify-content: center; margin-left: 4px;
+}
+.tab-add:hover { background: #d0d3d6; color: #1a73e8; }
+
+.empty-state {
+  display: flex; align-items: center; justify-content: center; height: 100%;
+  color: #9ca3af; font-size: 14px; text-align: center; padding: 40px;
+}
+
 #main { display: flex; flex: 1; overflow: hidden; }
 
 #sidebar {
diff --git a/templates/index.html b/templates/index.html
index c78e869..b1bc14b 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -19,12 +19,17 @@
       <label for="fileInput" class="btn btn-primary"><i class="fas fa-upload"></i> 엑셀 업로드</label>
       <input type="file" id="fileInput" accept=".xlsx,.xls" hidden />
     </form>
-    <button class="btn btn-success" id="exportBtn" onclick="exportExcel()"><i class="fas fa-download"></i> 내보내기</button>
-    <button class="btn btn-danger" id="resetBtn" onclick="resetAssignments()"><i class="fas fa-undo"></i> 초기화</button>
+    <button class="btn btn-success" onclick="exportExcel()"><i class="fas fa-download"></i> 내보내기</button>
+    <button class="btn btn-danger" onclick="resetAssignments()"><i class="fas fa-undo"></i> 초기화</button>
     <span id="statusBadge" class="status-badge"></span>
   </div>
 </div>
 
+<div id="tabBar">
+  <div id="tabList" class="tab-list"></div>
+  <button class="tab-add" onclick="addTab()" title="새 탭 추가"><i class="fas fa-plus"></i></button>
+</div>
+
 <div id="main">
   <div id="sidebar">
     <div class="sidebar-header">
@@ -33,7 +38,6 @@
     </div>
     <div id="workerList" class="worker-list"></div>
   </div>
-
   <div id="mapContainer">
     <div id="map"></div>
     <div id="dropOverlay">여기에 드롭하여 배치</div>
@@ -45,34 +49,151 @@
 <script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"></script>
 <script>
 const YONGSAN = [37.5326, 126.9906];
-
-let map, store;
-
+let map;
 const WORKER_ICON = L.divIcon({
   className: 'marker-icon worker-marker',
   html: '<i class="fas fa-user"></i>',
-  iconSize: [36, 36],
-  iconAnchor: [18, 36],
-  popupAnchor: [0, -40],
+  iconSize: [36, 36], iconAnchor: [18, 36], popupAnchor: [0, -40],
 });
-
 const WORKER_ASSIGNED_ICON = L.divIcon({
   className: 'marker-icon worker-assigned-marker',
   html: '<i class="fas fa-user-check"></i>',
-  iconSize: [36, 36],
-  iconAnchor: [18, 36],
-  popupAnchor: [0, -40],
+  iconSize: [36, 36], iconAnchor: [18, 36], popupAnchor: [0, -40],
 });
-
 const WORKPLACE_ICON = L.divIcon({
   className: 'marker-icon workplace-marker',
   html: '<i class="fas fa-building"></i>',
-  iconSize: [42, 42],
-  iconAnchor: [21, 42],
-  popupAnchor: [0, -40],
+  iconSize: [42, 42], iconAnchor: [21, 42], popupAnchor: [0, -40],
 });
 
 let markers = { workers: {}, workplaces: {} };
+let tabs = [];
+let activeTabId = null;
+
+// caches the current tab's data loaded from server
+let tabDataCache = {};
+
+async function api(url, opts = {}) {
+  const resp = await fetch(url, opts);
+  if (!resp.ok) throw new Error(await resp.text());
+  return resp.json();
+}
+
+function tabQuery() { return activeTabId ? `?tab=${activeTabId}` : ''; }
+function tabBody() { return { tab: activeTabId }; }
+
+// ── Tab management ──
+
+async function loadTabs() {
+  const r = await api('/api/tabs');
+  tabs = r.tabs;
+  activeTabId = r.activeTab;
+  renderTabBar();
+  if (activeTabId) {
+    await loadTabData(activeTabId);
+  } else {
+    document.getElementById('workerList').innerHTML = '<div class="empty-state">새 탭을 추가하거나 엑셀 파일을 업로드하세요</div>';
+  }
+}
+
+async function loadTabData(tid) {
+  const r = await api(`/api/data?tab=${tid}`);
+  tabDataCache[tid] = r;
+  if (tid === activeTabId) render();
+}
+
+function currentData() {
+  return tabDataCache[activeTabId] || { workers: [], workplaces: [], assignments: {} };
+}
+
+async function addTab() {
+  const name = prompt('탭 이름을 입력하세요 (예: 5/12, 1차 등)');
+  if (name === null) return;
+  const r = await api('/api/tabs/add', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ name: name.trim() || undefined }),
+  });
+  tabDataCache[r.id] = { workers: [], workplaces: [], assignments: {} };
+  activeTabId = r.id;
+  await loadTabs();
+}
+
+async function renameTab(e, tid) {
+  e.stopPropagation();
+  const tab = tabs.find(t => t.id === tid);
+  if (!tab) return;
+  const name = prompt('새 이름을 입력하세요', tab.name);
+  if (!name || name.trim() === tab.name) return;
+  await api('/api/tabs/rename', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ id: tid, name: name.trim() }),
+  });
+  await loadTabs();
+}
+
+async function deleteTab(e, tid) {
+  e.stopPropagation();
+  if (tabs.length <= 1) { showToast('최소 1개의 탭이 필요합니다.', 'warning'); return; }
+  if (!confirm('이 탭을 삭제하시겠습니까? 데이터가 모두 사라집니다.')) return;
+  await api('/api/tabs/delete', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ id: tid }),
+  });
+  delete tabDataCache[tid];
+  await loadTabs();
+}
+
+async function switchTab(tid) {
+  if (tid === activeTabId) return;
+  activeTabId = tid;
+  await api('/api/tabs/activate', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ id: tid }),
+  });
+  if (!tabDataCache[tid]) await loadTabData(tid);
+  else render();
+  renderTabBar();
+  document.getElementById('statusBadge').className = 'status-badge';
+}
+
+function renderTabBar() {
+  const list = document.getElementById('tabList');
+  list.innerHTML = '';
+  for (const tab of tabs) {
+    const el = document.createElement('div');
+    el.className = `tab-item ${tab.id === activeTabId ? 'active' : ''}`;
+
+    const nameSpan = document.createElement('span');
+    nameSpan.className = 'tab-name';
+    nameSpan.textContent = tab.name;
+    nameSpan.title = '더블클릭하여 이름 변경';
+
+    const badge = document.createElement('span');
+    badge.className = 'tab-badge';
+    badge.textContent = `${tab.assignCount}/${tab.workerCount}`;
+
+    const del = document.createElement('span');
+    del.className = 'tab-del';
+    del.innerHTML = '&times;';
+    del.title = '탭 삭제';
+
+    el.appendChild(nameSpan);
+    el.appendChild(badge);
+    el.appendChild(del);
+
+    el.addEventListener('click', () => switchTab(tab.id));
+    nameSpan.addEventListener('dblclick', (e) => renameTab(e, tab.id));
+    del.addEventListener('click', (e) => deleteTab(e, tab.id));
+
+    list.appendChild(el);
+  }
+}
+
+// ── Map ──
 
 function init() {
   map = L.map('map').setView(YONGSAN, 14);
@@ -81,67 +202,48 @@ function init() {
     attribution: '&copy; OpenStreetMap contributors',
   }).addTo(map);
 
-  const mapContainer = document.getElementById('mapContainer');
-
-  mapContainer.addEventListener('dragover', (e) => {
-    e.preventDefault();
-    e.dataTransfer.dropEffect = 'move';
-    document.getElementById('dropOverlay').classList.add('active');
-  });
-
-  mapContainer.addEventListener('dragleave', (e) => {
-    document.getElementById('dropOverlay').classList.remove('active');
-  });
-
-  mapContainer.addEventListener('drop', (e) => {
+  const mc = document.getElementById('mapContainer');
+  mc.addEventListener('dragover', e => { e.preventDefault(); e.dataTransfer.dropEffect = 'move'; document.getElementById('dropOverlay').classList.add('active'); });
+  mc.addEventListener('dragleave', () => document.getElementById('dropOverlay').classList.remove('active'));
+  mc.addEventListener('drop', e => {
     e.preventDefault();
     document.getElementById('dropOverlay').classList.remove('active');
     const workerId = e.dataTransfer.getData('text/plain');
-    if (!workerId || !store) return;
-
+    if (!workerId || !activeTabId) return;
     const rect = map.getContainer().getBoundingClientRect();
-    const x = e.clientX - rect.left;
-    const y = e.clientY - rect.top;
-    const latlng = map.containerPointToLatLng([x, y]);
-
+    const latlng = map.containerPointToLatLng([e.clientX - rect.left, e.clientY - rect.top]);
     const nearest = findNearestWorkplace(latlng.lat, latlng.lng);
-    if (!nearest) {
-      showToast('근무지 마커 근처에 드롭해주세요.', 'warning');
-      return;
-    }
+    if (!nearest) { showToast('근무지 마커 근처에 드롭해주세요.', 'warning'); return; }
     doAssignWorker(workerId, nearest.id);
   });
 
   document.getElementById('fileInput').addEventListener('change', uploadExcel);
+  loadTabs();
 }
 
 function findNearestWorkplace(lat, lng) {
+  const d = currentData();
   const threshold = 0.002;
   let best = null, bestDist = Infinity;
-  for (const wp of (store?.workplaces || [])) {
-    const d = Math.abs(wp.lat - lat) + Math.abs(wp.lng - lng);
-    if (d < threshold && d < bestDist) {
-      bestDist = d;
-      best = wp;
-    }
+  for (const wp of (d.workplaces || [])) {
+    const dist = Math.abs(wp.lat - lat) + Math.abs(wp.lng - lng);
+    if (dist < threshold && dist < bestDist) { bestDist = dist; best = wp; }
   }
   return best;
 }
 
 async function uploadExcel(e) {
   const file = e.target.files[0];
-  if (!file) return;
-
+  if (!file || !activeTabId) return;
   const form = new FormData();
   form.append('file', file);
-
+  form.append('tab', activeTabId);
   showToast('업로드 중...', 'info');
-
   try {
-    const resp = await fetch('/upload', { method: 'POST', body: form });
-    if (!resp.ok) throw new Error('업로드 실패');
-    store = await resp.json();
+    const r = await api('/api/upload', { method: 'POST', body: form });
+    tabDataCache[activeTabId] = r;
     render();
+    await loadTabs();
     showToast(`파일 로드 완료: ${file.name}`, 'success');
   } catch (err) {
     showToast('업로드 실패: ' + err.message, 'error');
@@ -149,8 +251,10 @@ async function uploadExcel(e) {
   e.target.value = '';
 }
 
+// ── Rendering ──
+
 function render() {
-  if (!store) return;
+  if (!activeTabId) return;
   clearMap();
   renderWorkplaceMarkers();
   renderWorkerMarkers();
@@ -159,88 +263,69 @@ function render() {
 }
 
 function clearMap() {
-  for (const key in markers.workers) {
-    map.removeLayer(markers.workers[key]);
-  }
-  for (const key in markers.workplaces) {
-    map.removeLayer(markers.workplaces[key]);
-  }
+  for (const k in markers.workers) map.removeLayer(markers.workers[k]);
+  for (const k in markers.workplaces) map.removeLayer(markers.workplaces[k]);
   markers = { workers: {}, workplaces: {} };
 }
 
 function getWorkplaceAssigneesHtml(wpId) {
-  const assigned = store.workers.filter(w => store.assignments[w.id] === wpId);
+  const d = currentData();
+  const assigned = d.workers.filter(w => d.assignments[w.id] === wpId);
   if (assigned.length === 0) return '<div class="wp-assignees" style="color:#9ca3af;">배정된 근무자 없음</div>';
-  return '<div class="wp-assignees"><strong>배정된 근무자</strong><ul style="margin:4px 0 0 0;padding-left:16px;">' +
+  return '<div class="wp-assignees"><strong>배정된 근무자</strong><ul style="margin:4px 0 0 16px;">' +
     assigned.map(w => `<li>${escHtml(w.name)}</li>`).join('') + '</ul></div>';
 }
 
 function renderWorkplaceMarkers() {
+  const d = currentData();
   const bounds = [];
-  for (const wp of store.workplaces) {
+  for (const wp of d.workplaces) {
     const marker = L.marker([wp.lat, wp.lng], { icon: WORKPLACE_ICON })
-      .addTo(map)
-      .bindPopup(`
+      .addTo(map).bindPopup(`
         <div class="popup-content">
           <strong><i class="fas fa-building"></i> ${escHtml(wp.name)}</strong><br>
           <small>${escHtml(wp.address)}</small>
           ${getWorkplaceAssigneesHtml(wp.id)}
-        </div>
-      `);
+        </div>`);
     markers.workplaces[wp.id] = marker;
     bounds.push([wp.lat, wp.lng]);
   }
-  if (bounds.length > 0) {
-    map.fitBounds(bounds, { padding: [50, 50], maxZoom: 16 });
-  }
+  if (bounds.length > 0) map.fitBounds(bounds, { padding: [50, 50], maxZoom: 16 });
 }
 
 function getWorkerPos(w) {
-  const wpId = store.assignments[w.id];
+  const d = currentData();
+  const wpId = d.assignments[w.id];
   if (wpId) {
-    const wp = store.workplaces.find(p => p.id === wpId);
+    const wp = d.workplaces.find(p => p.id === wpId);
     if (wp) return [wp.lat, wp.lng];
   }
   return [w.lat, w.lng];
 }
 
 function renderWorkerMarkers() {
-  for (const w of store.workers) {
-    const isAssigned = store.assignments[w.id];
-    const icon = isAssigned ? WORKER_ASSIGNED_ICON : WORKER_ICON;
-    const marker = L.marker(getWorkerPos(w), { icon, draggable: true })
-      .addTo(map)
-      .bindPopup(`
-        <div class="popup-content">
-          <strong><i class="fas fa-user"></i> ${escHtml(w.name)}</strong><br>
-          <small>${escHtml(w.address)}</small><br>
-          <small>${escHtml(w.phone)}</small>
-          <div class="worker-status" id="worker-status-${w.id}">
-            ${isAssigned ? `<span class="tag-assigned">배치됨 → ${escHtml(getWorkplaceName(isAssigned))}</span>` : '<span class="tag-unassigned">미배치</span>'}
-          </div>
-          ${isAssigned ? `<button class="btn-small btn-danger" onclick="unassignWorker('${w.id}', true)">배치 취소</button>` : ''}
-        </div>
-      `);
-    marker.on('dragend', function () {
-      handleWorkerDragEnd(w.id, this);
-    });
+  const d = currentData();
+  for (const w of d.workers) {
+    const isAssigned = d.assignments[w.id];
+    const marker = L.marker(getWorkerPos(w), { icon: isAssigned ? WORKER_ASSIGNED_ICON : WORKER_ICON, draggable: true })
+      .addTo(map).bindPopup(buildWorkerPopup(w.id));
+    marker.on('dragend', function () { handleWorkerDragEnd(w.id, this); });
     markers.workers[w.id] = marker;
   }
 }
 
 function handleWorkerDragEnd(workerId, marker) {
+  const d = currentData();
   const pos = marker.getLatLng();
   const nearest = findNearestWorkplace(pos.lat, pos.lng);
 
   if (nearest) {
-    fetch('/assign', {
+    api('/api/assign', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ workerId, workplaceId: nearest.id }),
-    })
-    .then(r => r.json())
-    .then(data => {
-      store.assignments = data.assignments;
+      body: JSON.stringify({ workerId, workplaceId: nearest.id, tab: activeTabId }),
+    }).then(data => {
+      tabDataCache[activeTabId].assignments = data.assignments;
       marker.setLatLng([nearest.lat, nearest.lng]);
       marker.setIcon(WORKER_ASSIGNED_ICON);
       marker.setPopupContent(buildWorkerPopup(workerId));
@@ -248,19 +333,17 @@ function handleWorkerDragEnd(workerId, marker) {
       renderWorkerList();
       updateBadges();
       showToast(`${getWorkerName(workerId)} → ${nearest.name} 배치됨`, 'success');
-    })
-    .catch(() => showToast('배치 저장 실패', 'error'));
-  } else if (store.assignments[workerId]) {
-    const oldWpId = store.assignments[workerId];
-    fetch('/unassign', {
+    }).catch(() => showToast('배치 저장 실패', 'error'));
+
+  } else if (d.assignments[workerId]) {
+    const oldWpId = d.assignments[workerId];
+    api('/api/unassign', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ workerId }),
-    })
-    .then(r => r.json())
-    .then(data => {
-      store.assignments = data.assignments;
-      const w = store.workers.find(x => x.id === workerId);
+      body: JSON.stringify({ workerId, tab: activeTabId }),
+    }).then(data => {
+      tabDataCache[activeTabId].assignments = data.assignments;
+      const w = d.workers.find(x => x.id === workerId);
       marker.setLatLng([w.lat, w.lng]);
       marker.setIcon(WORKER_ICON);
       marker.setPopupContent(buildWorkerPopup(workerId));
@@ -268,18 +351,19 @@ function handleWorkerDragEnd(workerId, marker) {
       renderWorkerList();
       updateBadges();
       showToast('배치가 취소되었습니다.', 'info');
-    })
-    .catch(() => showToast('배치 취소 실패', 'error'));
+    }).catch(() => showToast('배치 취소 실패', 'error'));
+
   } else {
-    const w = store.workers.find(x => x.id === workerId);
+    const w = d.workers.find(x => x.id === workerId);
     marker.setLatLng([w.lat, w.lng]);
   }
 }
 
 function buildWorkerPopup(workerId) {
-  const w = store.workers.find(x => x.id === workerId);
+  const d = currentData();
+  const w = d.workers.find(x => x.id === workerId);
   if (!w) return '';
-  const isAssigned = store.assignments[w.id];
+  const isAssigned = d.assignments[w.id];
   const wpName = isAssigned ? getWorkplaceName(isAssigned) : '';
   return `
     <div class="popup-content">
@@ -294,20 +378,20 @@ function buildWorkerPopup(workerId) {
 }
 
 function getWorkerName(id) {
-  const w = store.workers.find(x => x.id === id);
+  const w = currentData().workers.find(x => x.id === id);
   return w ? w.name : '';
 }
 
 function renderWorkerList() {
+  const d = currentData();
   const list = document.getElementById('workerList');
   list.innerHTML = '';
-  for (const w of store.workers) {
-    const isAssigned = store.assignments[w.id];
+  for (const w of d.workers) {
+    const isAssigned = d.assignments[w.id];
     const card = document.createElement('div');
     card.className = `worker-card ${isAssigned ? 'assigned' : ''}`;
     card.draggable = true;
     card.dataset.workerId = w.id;
-
     card.innerHTML = `
       <div class="worker-card-avatar ${isAssigned ? 'assigned' : ''}">
         <i class="fas ${isAssigned ? 'fa-user-check' : 'fa-user'}"></i>
@@ -320,59 +404,53 @@ function renderWorkerList() {
         <div class="worker-card-assignment">
           ${isAssigned ? `<span class="tag-assigned"><i class="fas fa-check-circle"></i> ${escHtml(getWorkplaceName(isAssigned))}</span>` : '<span class="tag-unassigned">미배치</span>'}
         </div>
-      </div>
-    `;
-
-    card.addEventListener('dragstart', (e) => {
-      e.dataTransfer.setData('text/plain', w.id);
-      e.dataTransfer.effectAllowed = 'move';
-      card.classList.add('dragging');
-    });
-
-    card.addEventListener('dragend', (e) => {
-      card.classList.remove('dragging');
-    });
-
+      </div>`;
+    card.addEventListener('dragstart', e => { e.dataTransfer.setData('text/plain', w.id); e.dataTransfer.effectAllowed = 'move'; card.classList.add('dragging'); });
+    card.addEventListener('dragend', () => card.classList.remove('dragging'));
     list.appendChild(card);
   }
+  if (d.workers.length === 0) {
+    list.innerHTML = '<div class="empty-state">엑셀 파일을 업로드하세요</div>';
+  }
 }
 
 function updateWorkplacePopup(wpId) {
+  const d = currentData();
   const marker = markers.workplaces[wpId];
-  if (!marker) return;
-  const wp = store.workplaces.find(p => p.id === wpId);
-  if (!wp) return;
+  const wp = d.workplaces.find(p => p.id === wpId);
+  if (!marker || !wp) return;
   marker.setPopupContent(`
     <div class="popup-content">
       <strong><i class="fas fa-building"></i> ${escHtml(wp.name)}</strong><br>
       <small>${escHtml(wp.address)}</small>
       ${getWorkplaceAssigneesHtml(wpId)}
-    </div>
-  `);
+    </div>`);
 }
 
 function updateBadges() {
-  const assigned = Object.keys(store.assignments).length;
-  const total = store.workers.length;
+  const d = currentData();
+  const assigned = Object.keys(d.assignments).length;
+  const total = d.workers.length;
   document.getElementById('workerCount').textContent = `${assigned}/${total}`;
-  document.getElementById('statusBadge').textContent = assigned > 0 ? `배치 ${assigned}/${total}` : '';
-  document.getElementById('statusBadge').className = `status-badge ${assigned === total ? 'complete' : assigned > 0 ? 'partial' : ''}`;
+  const badge = document.getElementById('statusBadge');
+  badge.textContent = assigned > 0 ? `배치 ${assigned}/${total}` : '';
+  badge.className = `status-badge ${!total ? '' : assigned === total ? 'complete' : assigned > 0 ? 'partial' : ''}`;
 }
 
-function doAssignWorker(workerId, workplaceId) {
-  if (!store) return;
-  if (store.assignments[workerId] === workplaceId) return;
+// ── Actions ──
 
-  fetch('/assign', {
-    method: 'POST',
-    headers: { 'Content-Type': 'application/json' },
-    body: JSON.stringify({ workerId, workplaceId }),
-  })
-  .then(r => r.json())
-  .then(data => {
-    store.assignments = data.assignments;
-    const w = store.workers.find(x => x.id === workerId);
-    const wp = store.workplaces.find(p => p.id === workplaceId);
+async function doAssignWorker(workerId, workplaceId) {
+  if (!activeTabId) return;
+  const d = currentData();
+  if (d.assignments[workerId] === workplaceId) return;
+  try {
+    const r = await api('/api/assign', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ workerId, workplaceId, tab: activeTabId }),
+    });
+    tabDataCache[activeTabId].assignments = r.assignments;
+    const wp = d.workplaces.find(p => p.id === workplaceId);
     const marker = markers.workers[workerId];
     if (marker) {
       marker.setLatLng([wp.lat, wp.lng]);
@@ -383,23 +461,21 @@ function doAssignWorker(workerId, workplaceId) {
     renderWorkerList();
     updateBadges();
     showToast('배치가 저장되었습니다.', 'success');
-  })
-  .catch(() => showToast('배치 저장 실패', 'error'));
+  } catch { showToast('배치 저장 실패', 'error'); }
 }
 
-function unassignWorker(workerId, fromPopup) {
-  if (!store) return;
-
-  fetch('/unassign', {
-    method: 'POST',
-    headers: { 'Content-Type': 'application/json' },
-    body: JSON.stringify({ workerId }),
-  })
-  .then(r => r.json())
-  .then(data => {
-    const oldWpId = store.assignments[workerId];
-    store.assignments = data.assignments;
-    const w = store.workers.find(x => x.id === workerId);
+async function unassignWorker(workerId, fromPopup) {
+  if (!activeTabId) return;
+  const d = currentData();
+  const oldWpId = d.assignments[workerId];
+  try {
+    const r = await api('/api/unassign', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ workerId, tab: activeTabId }),
+    });
+    tabDataCache[activeTabId].assignments = r.assignments;
+    const w = d.workers.find(x => x.id === workerId);
     const marker = markers.workers[workerId];
     if (marker) {
       marker.setLatLng([w.lat, w.lng]);
@@ -411,46 +487,44 @@ function unassignWorker(workerId, fromPopup) {
     updateBadges();
     if (fromPopup) map.closePopup();
     showToast('배치가 취소되었습니다.', 'info');
-  })
-  .catch(() => showToast('배치 취소 실패', 'error'));
+  } catch { showToast('배치 취소 실패', 'error'); }
 }
 
-function resetAssignments() {
-  if (!store || Object.keys(store.assignments).length === 0) return;
+async function resetAssignments() {
+  const d = currentData();
+  if (!activeTabId || Object.keys(d.assignments).length === 0) return;
   if (!confirm('모든 배치를 초기화하시겠습니까?')) return;
-
-  fetch('/reset', { method: 'POST' })
-    .then(r => r.json())
-    .then(data => {
-      store.assignments = data.assignments;
-      for (const w of store.workers) {
-        const marker = markers.workers[w.id];
-        if (marker) {
-          marker.setLatLng([w.lat, w.lng]);
-          marker.setIcon(WORKER_ICON);
-          marker.setPopupContent(buildWorkerPopup(w.id));
-        }
+  try {
+    await api('/api/reset', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ tab: activeTabId }),
+    });
+    tabDataCache[activeTabId].assignments = {};
+    for (const w of d.workers) {
+      const marker = markers.workers[w.id];
+      if (marker) {
+        marker.setLatLng([w.lat, w.lng]);
+        marker.setIcon(WORKER_ICON);
+        marker.setPopupContent(buildWorkerPopup(w.id));
       }
-      for (const wp of store.workplaces) {
-        updateWorkplacePopup(wp.id);
-      }
-      renderWorkerList();
-      updateBadges();
-      showToast('모든 배치가 초기화되었습니다.', 'info');
-    })
-    .catch(() => showToast('초기화 실패', 'error'));
+    }
+    for (const wp of d.workplaces) updateWorkplacePopup(wp.id);
+    renderWorkerList();
+    updateBadges();
+    showToast('모든 배치가 초기화되었습니다.', 'info');
+  } catch { showToast('초기화 실패', 'error'); }
 }
 
 function exportExcel() {
-  if (!store || store.workers.length === 0) {
-    showToast('내보낼 데이터가 없습니다.', 'warning');
-    return;
-  }
-  window.location.href = '/export';
+  if (!activeTabId) { showToast('내보낼 탭이 없습니다.', 'warning'); return; }
+  const d = currentData();
+  if (d.workers.length === 0) { showToast('내보낼 데이터가 없습니다.', 'warning'); return; }
+  window.location.href = `/api/export?tab=${activeTabId}`;
 }
 
 function getWorkplaceName(id) {
-  const wp = store.workplaces.find(p => p.id === id);
+  const wp = currentData().workplaces.find(p => p.id === id);
   return wp ? wp.name : '(알 수 없음)';
 }