diff --git a/packages/backend/convex/notifications.ts b/packages/backend/convex/notifications.ts
index af9a373..d3c04f4 100644
--- a/packages/backend/convex/notifications.ts
+++ b/packages/backend/convex/notifications.ts
@@ -1,9 +1,15 @@
-import { v } from 'convex/values';
+import { ConvexError, v } from 'convex/values';
 
 import type { Doc, Id } from './_generated/dataModel';
 import type { MutationCtx } from './_generated/server';
 import { internal } from './_generated/api';
-import { internalMutation, internalQuery } from './_generated/server';
+import {
+  internalMutation,
+  internalQuery,
+  mutation,
+  query,
+} from './_generated/server';
+import { getRequiredUserId } from './model';
 
 export type NotificationKind =
   | 'maintenance_thread'
@@ -139,3 +145,78 @@ export const getForEmail = internalQuery({
     };
   },
 });
+
+/**
+ * The authed caller's notifications, newest-first. Scoped to the caller via
+ * `getRequiredUserId`; never accepts a userId argument.
+ */
+export const listMine = query({
+  args: { limit: v.optional(v.number()) },
+  handler: async (ctx, args): Promise<Doc<'notifications'>[]> => {
+    const userId = await getRequiredUserId(ctx);
+    return await ctx.db
+      .query('notifications')
+      .withIndex('by_user_created', (q) => q.eq('userId', userId))
+      .order('desc')
+      .take(args.limit ?? 30);
+  },
+});
+
+/**
+ * How many of the caller's notifications are unread. Bounded at 100 via the
+ * `by_user_unread` index so the header bell stays cheap.
+ */
+export const unreadCount = query({
+  args: {},
+  handler: async (ctx): Promise<number> => {
+    const userId = await getRequiredUserId(ctx);
+    const unread = await ctx.db
+      .query('notifications')
+      .withIndex('by_user_unread', (q) =>
+        q.eq('userId', userId).eq('readAt', undefined),
+      )
+      .take(100);
+    return unread.length;
+  },
+});
+
+/**
+ * Marks a single notification read. Loads the row and asserts it belongs to the
+ * caller before patching, so a user can never mark another user's notification
+ * read (indistinguishable from a missing row).
+ */
+export const markRead = mutation({
+  args: { notificationId: v.id('notifications') },
+  handler: async (ctx, { notificationId }): Promise<void> => {
+    const userId = await getRequiredUserId(ctx);
+    const notification = await ctx.db.get(notificationId);
+    if (notification?.userId !== userId) {
+      throw new ConvexError('Notification not found.');
+    }
+    if (notification.readAt === undefined) {
+      await ctx.db.patch(notificationId, { readAt: Date.now() });
+    }
+  },
+});
+
+/**
+ * Marks all of the caller's unread notifications read. Iterates the caller's
+ * unread rows via the `by_user_unread` index; only ever touches the caller's
+ * own notifications.
+ */
+export const markAllRead = mutation({
+  args: {},
+  handler: async (ctx): Promise<void> => {
+    const userId = await getRequiredUserId(ctx);
+    const unread = await ctx.db
+      .query('notifications')
+      .withIndex('by_user_unread', (q) =>
+        q.eq('userId', userId).eq('readAt', undefined),
+      )
+      .collect();
+    const now = Date.now();
+    for (const notification of unread) {
+      await ctx.db.patch(notification._id, { readAt: now });
+    }
+  },
+});
diff --git a/packages/backend/tests/unit/notifications.test.ts b/packages/backend/tests/unit/notifications.test.ts
index 9143dd8..d25167a 100644
--- a/packages/backend/tests/unit/notifications.test.ts
+++ b/packages/backend/tests/unit/notifications.test.ts
@@ -7,6 +7,12 @@ import schema from '../../convex/schema';
 
 const modules = import.meta.glob('../../convex/**/*.*s');
 
+const authed = (t: ReturnType<typeof convexTest>, userId: string) =>
+  t.withIdentity({
+    subject: `${userId}|session`,
+    issuer: 'https://convex.test',
+  });
+
 const countNotifications = async (
   t: ReturnType<typeof convexTest>,
   userId: Id<'users'>,
@@ -370,3 +376,122 @@ describe('emit points', () => {
     );
   });
 });
+
+describe('inbox query + mark-read mutations', () => {
+  const seedInbox = async (t: ReturnType<typeof convexTest>) =>
+    await t.run(async (ctx) => {
+      const userA = await ctx.db.insert('users', {
+        email: 'inbox-a@example.com',
+        name: 'Inbox A',
+      });
+      const userB = await ctx.db.insert('users', {
+        email: 'inbox-b@example.com',
+        name: 'Inbox B',
+      });
+      const base = 1_000_000;
+      // Three notifications for A with ascending createdAt (a3 is newest).
+      const a1 = await ctx.db.insert('notifications', {
+        userId: userA,
+        kind: 'agent_turn_finished',
+        title: 'A one',
+        body: 'first',
+        createdAt: base + 1,
+      });
+      const a2 = await ctx.db.insert('notifications', {
+        userId: userA,
+        kind: 'agent_turn_finished',
+        title: 'A two',
+        body: 'second',
+        createdAt: base + 2,
+      });
+      const a3 = await ctx.db.insert('notifications', {
+        userId: userA,
+        kind: 'agent_needs_input',
+        title: 'A three',
+        body: 'third',
+        createdAt: base + 3,
+      });
+      // One notification for B, which must never leak to A.
+      const b1 = await ctx.db.insert('notifications', {
+        userId: userB,
+        kind: 'sync_failed',
+        title: 'B one',
+        body: 'b first',
+        createdAt: base + 4,
+      });
+      return { userA, userB, a1, a2, a3, b1 };
+    });
+
+  test('listMine returns only the caller notifications, newest-first, capped by limit', async () => {
+    const t = convexTest(schema, modules);
+    const { userA, a1, a2, a3 } = await seedInbox(t);
+
+    const all = await authed(t, userA).query(api.notifications.listMine, {});
+    expect(all.map((n) => n._id)).toEqual([a3, a2, a1]);
+    // No notification belongs to any other user.
+    expect(all.every((n) => n.userId === userA)).toBe(true);
+
+    const limited = await authed(t, userA).query(api.notifications.listMine, {
+      limit: 2,
+    });
+    expect(limited.map((n) => n._id)).toEqual([a3, a2]);
+  });
+
+  test('unreadCount counts only the caller unread notifications', async () => {
+    const t = convexTest(schema, modules);
+    const { userA, userB } = await seedInbox(t);
+
+    expect(await authed(t, userA).query(api.notifications.unreadCount, {})).toBe(
+      3,
+    );
+    // B has a single unread notification; A's three do not leak in.
+    expect(await authed(t, userB).query(api.notifications.unreadCount, {})).toBe(
+      1,
+    );
+  });
+
+  test('markRead marks the caller notification and drops unreadCount', async () => {
+    const t = convexTest(schema, modules);
+    const { userA, a1 } = await seedInbox(t);
+
+    await authed(t, userA).mutation(api.notifications.markRead, {
+      notificationId: a1,
+    });
+
+    const notification = await t.run(async (ctx) => await ctx.db.get(a1));
+    expect(typeof notification?.readAt).toBe('number');
+    expect(await authed(t, userA).query(api.notifications.unreadCount, {})).toBe(
+      2,
+    );
+  });
+
+  test('markRead rejects a notification owned by another user', async () => {
+    const t = convexTest(schema, modules);
+    const { userA, b1 } = await seedInbox(t);
+
+    await expect(
+      authed(t, userA).mutation(api.notifications.markRead, {
+        notificationId: b1,
+      }),
+    ).rejects.toThrow('Notification not found.');
+
+    // B's notification is untouched and B still has one unread.
+    const notification = await t.run(async (ctx) => await ctx.db.get(b1));
+    expect(notification?.readAt).toBeUndefined();
+  });
+
+  test('markAllRead zeroes the caller unread count but leaves other users untouched', async () => {
+    const t = convexTest(schema, modules);
+    const { userA, userB } = await seedInbox(t);
+
+    await authed(t, userA).mutation(api.notifications.markAllRead, {});
+
+    expect(await authed(t, userA).query(api.notifications.unreadCount, {})).toBe(
+      0,
+    );
+    // B's unread notification is left alone.
+    expect(await authed(t, userB).query(api.notifications.unreadCount, {})).toBe(
+      1,
+    );
+  });
+});