diff --git a/db.js b/db.js
index 31d91e0..9ecee90 100644
--- a/db.js
+++ b/db.js
@@ -39,7 +39,7 @@ async function getConversation(sessionId) {
   if (!p) return null;
 
   const result = await p.query(
-    'SELECT messages, user_id, todo_markdown, name FROM conversations WHERE session_id = $1',
+    'SELECT messages, user_id, todo_markdown, name, collapsed_sections FROM conversations WHERE session_id = $1',
     [sessionId]
   );
   if (result.rows.length === 0) return null;
@@ -47,7 +47,8 @@ async function getConversation(sessionId) {
     messages: result.rows[0].messages,
     userId: result.rows[0].user_id,
     todoMarkdown: result.rows[0].todo_markdown || '',
-    name: result.rows[0].name || null
+    name: result.rows[0].name || null,
+    collapsedSections: result.rows[0].collapsed_sections || {}
   };
 }
 
@@ -107,6 +108,21 @@ async function updateTodoMarkdown(sessionId, userId, todoMarkdown) {
   return result.rowCount;
 }
 
+// Persist a per-section collapsed/expanded state map so the same chat looks the
+// same on every device. Same ownership rule as updateTodoMarkdown.
+async function updateCollapsedSections(sessionId, userId, collapsedSections) {
+  const p = getPool();
+  if (!p) return 0;
+
+  const result = await p.query(
+    `UPDATE conversations
+     SET collapsed_sections = $1, updated_at = NOW()
+     WHERE session_id = $2 AND (user_id IS NULL OR user_id = $3)`,
+    [JSON.stringify(collapsedSections || {}), sessionId, userId]
+  );
+  return result.rowCount;
+}
+
 // Explicit user-initiated rename. Scoped to the owner so one user can't rename
 // another user's chats by guessing sessionIds.
 async function renameConversation(sessionId, userId, name) {
@@ -135,7 +151,7 @@ async function listConversationsByUser(userId) {
   if (!p) return [];
 
   const result = await p.query(
-    `SELECT session_id, messages, todo_markdown, name, updated_at
+    `SELECT session_id, messages, todo_markdown, name, collapsed_sections, updated_at
      FROM conversations
      WHERE user_id = $1
      ORDER BY updated_at DESC`,
@@ -146,6 +162,7 @@ async function listConversationsByUser(userId) {
     messages: r.messages,
     todoMarkdown: r.todo_markdown || '',
     name: r.name || null,
+    collapsedSections: r.collapsed_sections || {},
     updatedAt: r.updated_at
   }));
 }
@@ -181,6 +198,7 @@ module.exports = {
   getConversation,
   saveConversation,
   updateTodoMarkdown,
+  updateCollapsedSections,
   renameConversation,
   deleteConversation,
   listConversationsByUser,
diff --git a/index.html b/index.html
index 70016b1..0149c44 100644
--- a/index.html
+++ b/index.html
@@ -1186,6 +1186,9 @@ <h3>No tasks yet</h3>
                     if (sc.name) {
                         existing.name = sc.name;
                     }
+                    if (sc.collapsedSections && typeof sc.collapsedSections === 'object') {
+                        existing.collapsedSections = sc.collapsedSections;
+                    }
                     if (existing.id === currentSessionId) {
                         currentChatUpdated = true;
                     }
@@ -1201,7 +1204,8 @@ <h3>No tasks yet</h3>
                         id: sc.sessionId,
                         name: sc.name || derived,
                         todoMarkdown: sc.todoMarkdown || '',
-                        messages: sc.messages || []
+                        messages: sc.messages || [],
+                        collapsedSections: sc.collapsedSections || {}
                     });
                     addedNewChat = true;
                 }
@@ -1429,6 +1433,7 @@ <h3>No tasks yet</h3>
                         if (!collapseChat.collapsedSections) collapseChat.collapsedSections = {};
                         collapseChat.collapsedSections[sectionName] = isCollapsed;
                         saveChats();
+                        pushCollapsedSections(collapseChat.id, collapseChat.collapsedSections);
                     }
                 });
             });
@@ -1526,6 +1531,24 @@ <h3>No tasks yet</h3>
             } catch (e) { /* best-effort */ }
         }
 
+        async function pushCollapsedSections(sessionId, collapsedSections) {
+            if (!sessionId) return;
+            const headers = { 'Content-Type': 'application/json' };
+            try {
+                if (window.Clerk && window.Clerk.session) {
+                    const token = await window.Clerk.session.getToken();
+                    if (token) headers['Authorization'] = `Bearer ${token}`;
+                }
+            } catch (e) { /* fall through as guest */ }
+            try {
+                await fetch(`${API_BASE}/api/collapsed-sections`, {
+                    method: 'POST',
+                    headers,
+                    body: JSON.stringify({ sessionId, collapsedSections: collapsedSections || {} })
+                });
+            } catch (e) { /* best-effort */ }
+        }
+
         // API base URL - use Railway in production, relative URL in development
         const API_BASE = window.location.hostname === 'localhost'
             ? ''
diff --git a/migrations/005_add-collapsed-sections-to-conversations.cjs b/migrations/005_add-collapsed-sections-to-conversations.cjs
new file mode 100644
index 0000000..24df407
--- /dev/null
+++ b/migrations/005_add-collapsed-sections-to-conversations.cjs
@@ -0,0 +1,17 @@
+/* eslint-disable camelcase */
+
+exports.shorthands = undefined;
+
+exports.up = (pgm) => {
+  pgm.addColumn('conversations', {
+    collapsed_sections: {
+      type: 'jsonb',
+      notNull: true,
+      default: pgm.func("'{}'::jsonb")
+    }
+  });
+};
+
+exports.down = (pgm) => {
+  pgm.dropColumn('conversations', 'collapsed_sections');
+};
diff --git a/server.js b/server.js
index d252f93..a20f64f 100644
--- a/server.js
+++ b/server.js
@@ -216,6 +216,21 @@ app.post('/api/tasks', clerkAuth, async (req, res) => {
   res.json({ success: true });
 });
 
+// Persist the per-section collapsed/expanded state map for a chat so the
+// section toggle state syncs across devices.
+app.post('/api/collapsed-sections', clerkAuth, async (req, res) => {
+  const { sessionId, collapsedSections } = req.body;
+  if (!sessionId || typeof collapsedSections !== 'object' || collapsedSections === null || Array.isArray(collapsedSections)) {
+    return res.status(400).json({ error: 'sessionId and collapsedSections object are required' });
+  }
+  const row = await db.getConversation(sessionId);
+  if (row !== null && !canAccess(row.userId, req.userId)) {
+    return res.status(403).json({ error: 'forbidden' });
+  }
+  await db.updateCollapsedSections(sessionId, req.userId, collapsedSections).catch(() => {});
+  res.json({ success: true });
+});
+
 // Rename a conversation — persists the title so other devices see it on sync.
 // Scoped to the authenticated user so renames can't be spoofed across accounts.
 app.post('/api/rename', clerkAuth, requireAuth, async (req, res) => {
diff --git a/server.test.js b/server.test.js
index 4c9cdec..a9320b2 100644
--- a/server.test.js
+++ b/server.test.js
@@ -5,6 +5,7 @@ jest.mock('./db', () => ({
   getConversation: jest.fn().mockResolvedValue(null),
   saveConversation: jest.fn().mockResolvedValue(false),
   updateTodoMarkdown: jest.fn().mockResolvedValue(0),
+  updateCollapsedSections: jest.fn().mockResolvedValue(0),
   renameConversation: jest.fn().mockResolvedValue(0),
   deleteConversation: jest.fn().mockResolvedValue(false),
   listConversationsByUser: jest.fn().mockResolvedValue([]),
@@ -40,6 +41,7 @@ describe('PadTask Server', () => {
     db.getConversation.mockReset().mockResolvedValue(null);
     db.saveConversation.mockReset().mockResolvedValue(false);
     db.updateTodoMarkdown.mockReset().mockResolvedValue(0);
+    db.updateCollapsedSections.mockReset().mockResolvedValue(0);
     db.renameConversation.mockReset().mockResolvedValue(0);
     db.deleteConversation.mockReset().mockResolvedValue(false);
     db.listConversationsByUser.mockReset().mockResolvedValue([]);
@@ -703,6 +705,105 @@ describe('PadTask Server', () => {
     });
   });
 
+  describe('POST /api/collapsed-sections', () => {
+    it('should return 400 when sessionId is missing', async () => {
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ collapsedSections: { 'Today': true } });
+      expect(response.status).toBe(400);
+      expect(db.updateCollapsedSections).not.toHaveBeenCalled();
+    });
+
+    it('should return 400 when collapsedSections is not an object', async () => {
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ sessionId: 's1', collapsedSections: 'oops' });
+      expect(response.status).toBe(400);
+      expect(db.updateCollapsedSections).not.toHaveBeenCalled();
+    });
+
+    it('should return 400 when collapsedSections is an array', async () => {
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ sessionId: 's1', collapsedSections: ['Today'] });
+      expect(response.status).toBe(400);
+      expect(db.updateCollapsedSections).not.toHaveBeenCalled();
+    });
+
+    it('should return 400 when collapsedSections is null', async () => {
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ sessionId: 's1', collapsedSections: null });
+      expect(response.status).toBe(400);
+      expect(db.updateCollapsedSections).not.toHaveBeenCalled();
+    });
+
+    it('should update collapsed state for a guest on an unowned row', async () => {
+      db.getConversation.mockResolvedValue({ messages: [], userId: null, todoMarkdown: '', name: null });
+      db.updateCollapsedSections.mockResolvedValue(1);
+
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ sessionId: 's1', collapsedSections: { 'Today': true } });
+
+      expect(response.status).toBe(200);
+      expect(response.body.success).toBe(true);
+      expect(db.updateCollapsedSections).toHaveBeenCalledWith('s1', null, { 'Today': true });
+    });
+
+    it('should update collapsed state for the owner', async () => {
+      process.env.CLERK_SECRET_KEY = 'sk_test_dummy';
+      verifyToken.mockResolvedValue({ sub: 'user_a' });
+      db.getConversation.mockResolvedValue({ messages: [], userId: 'user_a', todoMarkdown: '', name: null });
+      db.updateCollapsedSections.mockResolvedValue(1);
+
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .set('Authorization', 'Bearer tok')
+        .send({ sessionId: 's1', collapsedSections: { 'Today': true, 'Later': false } });
+
+      expect(response.status).toBe(200);
+      expect(db.updateCollapsedSections).toHaveBeenCalledWith('s1', 'user_a', { 'Today': true, 'Later': false });
+    });
+
+    it('should reject when the row is owned by another user', async () => {
+      process.env.CLERK_SECRET_KEY = 'sk_test_dummy';
+      verifyToken.mockResolvedValue({ sub: 'user_b' });
+      db.getConversation.mockResolvedValue({ messages: [], userId: 'user_a', todoMarkdown: '', name: null });
+
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .set('Authorization', 'Bearer tok')
+        .send({ sessionId: 's1', collapsedSections: { 'Today': true } });
+
+      expect(response.status).toBe(403);
+      expect(db.updateCollapsedSections).not.toHaveBeenCalled();
+    });
+
+    it('should succeed when no DB row exists yet', async () => {
+      db.getConversation.mockResolvedValue(null);
+      db.updateCollapsedSections.mockResolvedValue(0);
+
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ sessionId: 's-new', collapsedSections: {} });
+
+      expect(response.status).toBe(200);
+      expect(db.updateCollapsedSections).toHaveBeenCalledWith('s-new', null, {});
+    });
+
+    it('should still respond 200 when the DB write rejects', async () => {
+      db.getConversation.mockResolvedValue(null);
+      db.updateCollapsedSections.mockRejectedValue(new Error('db down'));
+
+      const response = await request(app)
+        .post('/api/collapsed-sections')
+        .send({ sessionId: 's1', collapsedSections: { 'Today': true } });
+
+      expect(response.status).toBe(200);
+    });
+  });
+
   describe('POST /api/rename', () => {
     it('should return 401 when not authenticated', async () => {
       const response = await request(app)