diff --git a/lib/jmap/__tests__/search-merge.test.ts b/lib/jmap/__tests__/search-merge.test.ts
new file mode 100644
index 000000000..4bfa9135b
--- /dev/null
+++ b/lib/jmap/__tests__/search-merge.test.ts
@@ -0,0 +1,523 @@
+// @vitest-environment node
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { DEFAULT_SCOPE } from '@/lib/store/area';
+import { AccountEngine } from '@/lib/store/engine/account-engine';
+import { mailArea } from '@/lib/store/mail';
+import { FAKE_SESSION, FakeJmap, JMAP_ACCOUNT } from '@/lib/store/__tests__/helpers/fake-jmap';
+import { openMemoryStore } from '@/lib/store/__tests__/helpers/node-adapter';
+import { JMAPClient } from '../client';
+import type { SearchEmailsResult } from '../client-interface';
+import { setOfflineHooks, type OfflineHooks } from '../offline-hooks';
+import { filterHasTextTerms, LocalSearchMerge } from '../search-merge';
+import type { Email } from '../types';
+
+function mail(id: string, minute: number, extra: Partial<Email> = {}): Email {
+  return { id, receivedAt: new Date(Date.UTC(2026, 9, 1, 0, minute)).toISOString(), ...extra } as Email;
+}
+
+/** A side of the search: the whole result list, answered a page at a time, newest first. */
+function side(rows: Email[], total: number = rows.length) {
+  const asked: number[] = [];
+  const answer = async (position: number, limit: number): Promise<SearchEmailsResult> => {
+    asked.push(position);
+    const emails = rows.slice(position, position + limit);
+    return { emails, total, hasMore: position + emails.length < total };
+  };
+  return { asked, answer };
+}
+
+function pager(server: ReturnType<typeof side>, local: ReturnType<typeof side> | null, limit: number) {
+  const merge = new LocalSearchMerge();
+  return (position: number) => merge.run({
+    key: 'search',
+    limit,
+    position,
+    server: (at) => server.answer(at, limit),
+    local: async (at) => (local ? local.answer(at, limit) : null),
+  });
+}
+
+const ids = (result: SearchEmailsResult) => result.emails.map((email) => email.id);
+
+describe('merging one page', () => {
+  it('sorts newest first and has no duplicates', async () => {
+    const server = side([mail('s4', 40), mail('both3', 30), mail('s1', 10)]);
+    const local = side([mail('l5', 50), mail('both3', 30), mail('l2', 20)]);
+    const result = await pager(server, local, 50)(0);
+    expect(ids(result)).toEqual(['l5', 's4', 'both3', 'l2', 's1']);
+    expect(result.hasMore).toBe(false);
+    expect(result.total).toBe(5);
+  });
+
+  it('keeps the server copy when both have a message', async () => {
+    const server = side([mail('both', 10, { subject: 'server copy' })]);
+    const local = side([mail('both', 10, { subject: 'local copy' })]);
+    const result = await pager(server, local, 50)(0);
+    expect(result.emails.map((email) => email.subject)).toEqual(['server copy']);
+    expect(result.total).toBe(1);
+  });
+
+  it('keeps the server copy when the local row sorts earlier than it', async () => {
+    // The local copy is out of date and looks newer: still one row, the server's.
+    const server = side([mail('s2', 20), mail('both', 10, { subject: 'server copy' })]);
+    const local = side([mail('both', 30, { subject: 'local copy' })]);
+    const result = await pager(server, local, 50)(0);
+    expect(ids(result)).toEqual(['s2', 'both']);
+    expect(result.emails[1].subject).toBe('server copy');
+  });
+
+  it('passes on what the server added to its result, such as its deferred snippets', async () => {
+    const snippets = Promise.resolve([]);
+    const merge = new LocalSearchMerge();
+    const result = await merge.run({
+      key: 'k', limit: 10, position: 0,
+      server: async () => ({ emails: [mail('s', 1)], total: 1, hasMore: false, snippets }),
+      local: async () => ({ emails: [mail('l', 2)], total: 1, hasMore: false }),
+    });
+    expect(result.snippets).toBe(snippets);
+  });
+});
+
+describe('paging', () => {
+  it('walks both lists with no row lost or repeated, counting by merged rows', async () => {
+    const serverRows = Array.from({ length: 25 }, (_, i) => mail(`s${i}`, 1000 - i * 10));
+    const localOnly = [mail('l-a', 995), mail('l-b', 905), mail('l-c', 805), mail('l-d', 500)];
+    const server = side(serverRows);
+    const local = side([...localOnly, serverRows[1], serverRows[12]].sort((a, b) => Date.parse(b.receivedAt) - Date.parse(a.receivedAt)));
+    const page = pager(server, local, 10);
+
+    const seen: string[] = [];
+    let result = await page(0);
+    seen.push(...ids(result));
+    expect(result.emails.length).toBe(10);
+    expect(result.hasMore).toBe(true);
+    let guard = 0;
+    while (result.hasMore && guard < 10) {
+      // As the store does: the next position is how many rows it holds.
+      result = await page(seen.length);
+      seen.push(...ids(result));
+      guard += 1;
+    }
+    expect(seen.length).toBe(29);
+    expect(new Set(seen).size).toBe(29);
+    expect(seen).toEqual(expect.arrayContaining([...serverRows.map((e) => e.id), ...localOnly.map((e) => e.id)]));
+    const times = [...serverRows, ...localOnly].sort((a, b) => Date.parse(b.receivedAt) - Date.parse(a.receivedAt)).map((e) => e.id);
+    expect(seen).toEqual(times);
+    expect(result.total).toBe(29);
+  });
+
+  it('asks the server for rows a local row pushed off the page', async () => {
+    const server = side([mail('s3', 30), mail('s2', 20), mail('s1', 10)]);
+    const local = side([mail('l4', 40)]);
+    const page = pager(server, local, 2);
+    expect(ids(await page(0))).toEqual(['l4', 's3']);
+    expect(server.asked).toEqual([0]);
+    // Merged position 2, but the server has only given one row so far.
+    expect(ids(await page(2))).toEqual(['s2', 's1']);
+    expect(server.asked).toEqual([0, 1]);
+  });
+
+  it('holds back a local row older than what the server has sent, in case the server has it later', async () => {
+    const serverRows = [mail('s4', 40), mail('s3', 30), mail('both', 20), mail('s1', 10)];
+    const server = side(serverRows);
+    const local = side([mail('both', 20)]);
+    const page = pager(server, local, 2);
+    const first = await page(0);
+    expect(ids(first)).toEqual(['s4', 's3']);
+    const second = await page(2);
+    expect(ids(second)).toEqual(['both', 's1']);
+    expect(second.hasMore).toBe(false);
+    expect(second.total).toBe(4);
+  });
+
+  it('keeps paging through local rows when the server has none', async () => {
+    const server = side([]);
+    const local = side([mail('l3', 30), mail('l2', 20), mail('l1', 10)]);
+    const page = pager(server, local, 2);
+    const first = await page(0);
+    expect(ids(first)).toEqual(['l3', 'l2']);
+    expect(first.hasMore).toBe(true);
+    expect(first.total).toBe(3);
+    const second = await page(2);
+    expect(ids(second)).toEqual(['l1']);
+    expect(second.hasMore).toBe(false);
+    expect(second.total).toBe(3);
+  });
+
+  it('keeps total at or above what has been returned and what either side knows of', async () => {
+    const server = side([mail('s2', 20), mail('s1', 10)], 40);
+    const local = side([mail('l3', 30)], 50);
+    const result = await pager(server, local, 2)(0);
+    expect(result.total).toBe(50);
+    const noLocalLead = await pager(side([mail('s2', 20)], 40), side([mail('l3', 30)], 1), 2)(0);
+    expect(noLocalLead.total).toBe(41);
+  });
+
+  it('never repeats a local row the server later returns', async () => {
+    // Same time on both sides, split by the page edge: it shows once.
+    const server = side([mail('s', 20), mail('tie', 20)]);
+    const local = side([mail('tie', 20), mail('l', 5)]);
+    const page = pager(server, local, 1);
+    const seen = [...ids(await page(0))];
+    seen.push(...ids(await page(seen.length)));
+    seen.push(...ids(await page(seen.length)));
+    expect(seen).toEqual(['s', 'tie', 'l']);
+  });
+
+  it('drops a row the server returns later if the store already showed it, and holds older local rows until the server catches up', async () => {
+    // The local copy of x looks newer than the server's, so it goes out first.
+    const server = side([mail('a', 30), mail('b', 25), mail('x', 20), mail('c', 10)]);
+    const local = side([mail('x', 40), mail('l', 5)]);
+    const page = pager(server, local, 2);
+    const first = await page(0);
+    expect(ids(first)).toEqual(['x', 'a']);
+    // The server's page is b and x. x has been shown, and the server has more,
+    // so l can't be placed yet: it may be on the server's next page.
+    const second = await page(2);
+    expect(ids(second)).toEqual(['b']);
+    expect(second.hasMore).toBe(true);
+    const third = await page(3);
+    expect(ids(third)).toEqual(['c', 'l']);
+    expect(third.hasMore).toBe(false);
+  });
+
+  it('follows a caller whose position has moved since the last page', async () => {
+    const server = side([mail('s4', 40), mail('s3', 30), mail('s2', 20), mail('s1', 10)]);
+    const local = side([mail('l5', 50)]);
+    const page = pager(server, local, 2);
+    await page(0);
+    // The caller added a row of its own to the list, as plugins can: one past.
+    await page(3);
+    expect(server.asked).toEqual([0, 2]);
+  });
+
+  it('starts over at position 0', async () => {
+    const server = side([mail('s2', 20), mail('s1', 10)]);
+    const local = side([mail('l3', 30)]);
+    const page = pager(server, local, 2);
+    await page(0);
+    expect(ids(await page(0))).toEqual(['l3', 's2']);
+  });
+
+  it('sends a position it has no cursor for to the server alone', async () => {
+    const server = side([mail('s2', 20), mail('s1', 10)]);
+    const local = side([mail('l3', 30)]);
+    const result = await pager(server, local, 2)(1);
+    expect(ids(result)).toEqual(['s1']);
+    expect(local.asked).toEqual([]);
+  });
+
+  it('keeps searches apart by key', async () => {
+    const merge = new LocalSearchMerge();
+    const server = (rows: Email[]) => async (at: number) => ({ emails: rows.slice(at, at + 1), total: rows.length, hasMore: at + 1 < rows.length });
+    const a = { key: 'a', limit: 1, server: server([mail('a2', 20), mail('a1', 10)]), local: async () => ({ emails: [mail('la', 30)], total: 1, hasMore: false }) };
+    const b = { key: 'b', limit: 1, server: server([mail('b1', 10)]), local: async () => null };
+    expect(ids(await merge.run({ ...a, position: 0 }))).toEqual(['la']);
+    expect(ids(await merge.run({ ...b, position: 0 }))).toEqual(['b1']);
+    expect(ids(await merge.run({ ...a, position: 1 }))).toEqual(['a2']);
+  });
+});
+
+describe('errors', () => {
+  it('keeps the server result when the store fails', async () => {
+    const merge = new LocalSearchMerge();
+    const result = await merge.run({
+      key: 'k', limit: 10, position: 0,
+      server: async () => ({ emails: [mail('s', 1)], total: 1, hasMore: false }),
+      local: async () => { throw new Error('store broke'); },
+    });
+    expect(ids(result)).toEqual(['s']);
+  });
+
+  it('survives a store that fails before it can return a promise', async () => {
+    const merge = new LocalSearchMerge();
+    const result = await merge.run({
+      key: 'k', limit: 10, position: 0,
+      server: async () => ({ emails: [mail('s', 1)], total: 1, hasMore: false }),
+      local: () => { throw new Error('store broke'); },
+    });
+    expect(ids(result)).toEqual(['s']);
+  });
+
+  it('keeps the local result when the server fails', async () => {
+    const merge = new LocalSearchMerge();
+    const result = await merge.run({
+      key: 'k', limit: 10, position: 0,
+      server: async () => { throw new Error('server broke'); },
+      local: async () => ({ emails: [mail('l', 1)], total: 1, hasMore: false }),
+    });
+    expect(ids(result)).toEqual(['l']);
+    expect(result.total).toBe(1);
+    expect(result.hasMore).toBe(false);
+  });
+
+  it('asks the server again on the next page after it failed', async () => {
+    let fail = true;
+    const server = side([mail('s1', 10)]);
+    const merge = new LocalSearchMerge();
+    const run = (position: number) => merge.run({
+      key: 'k', limit: 1, position,
+      server: async (at) => {
+        if (fail) throw new Error('server broke');
+        return server.answer(at, 1);
+      },
+      local: async (at) => side([mail('l2', 20), mail('l1', 5)]).answer(at, 1),
+    });
+    expect(ids(await run(0))).toEqual(['l2']);
+    fail = false;
+    expect(ids(await run(1))).toEqual(['s1']);
+  });
+
+  it('keeps the server error when the store has nothing to show', async () => {
+    const failing = async () => { throw new Error('server broke'); };
+    await expect(new LocalSearchMerge().run({
+      key: 'k', limit: 10, position: 0, server: failing, local: async () => ({ emails: [], total: 0, hasMore: false }),
+    })).rejects.toThrow('server broke');
+    await expect(new LocalSearchMerge().run({
+      key: 'k', limit: 10, position: 0, server: failing, local: async () => null,
+    })).rejects.toThrow('server broke');
+    await expect(new LocalSearchMerge().run({
+      key: 'k', limit: 10, position: 0, server: failing, local: async () => { throw new Error('store broke too'); },
+    })).rejects.toThrow('server broke');
+  });
+
+  it('keeps the error of a later page, so the user can try again', async () => {
+    let fail = false;
+    const merge = new LocalSearchMerge();
+    const run = (position: number) => merge.run({
+      key: 'k', limit: 1, position,
+      server: async (at) => {
+        if (fail) throw new Error('server broke');
+        return side([mail('s2', 20), mail('s1', 10)]).answer(at, 1);
+      },
+      local: async (at) => side([mail('l3', 30)]).answer(at, 1),
+    });
+    expect(ids(await run(0))).toEqual(['l3']);
+    fail = true;
+    await expect(run(1)).rejects.toThrow('server broke');
+    fail = false;
+    expect(ids(await run(1))).toEqual(['s2']);
+  });
+
+  describe('with a store that never answers', () => {
+    beforeEach(() => { vi.useFakeTimers(); });
+    afterEach(() => { vi.useRealTimers(); });
+
+    it('does not hold the server result back for long', async () => {
+      const merge = new LocalSearchMerge();
+      const answer = merge.run({
+        key: 'k', limit: 10, position: 0,
+        server: async () => ({ emails: [mail('s', 1)], total: 1, hasMore: false }),
+        local: () => new Promise(() => {}),
+      });
+      await vi.advanceTimersByTimeAsync(1_000);
+      expect(ids(await answer)).toEqual(['s']);
+    });
+
+    it('gives the server error once it has waited for the store', async () => {
+      const merge = new LocalSearchMerge();
+      const answer = merge.run({
+        key: 'k', limit: 10, position: 0,
+        server: async () => { throw new Error('server broke'); },
+        local: () => new Promise(() => {}),
+      });
+      const failed = expect(answer).rejects.toThrow('server broke');
+      await vi.advanceTimersByTimeAsync(5_000);
+      await failed;
+    });
+  });
+});
+
+describe('filterHasTextTerms', () => {
+  it('is true for searches for text, in any shape', () => {
+    for (const filter of [
+      { text: 'x' }, { from: 'x' }, { to: 'x' }, { cc: 'x' }, { bcc: 'x' }, { subject: 'x' }, { body: 'x' },
+      { operator: 'AND', conditions: [{ inMailbox: 'i' }, { text: 'x' }] },
+      { operator: 'OR', conditions: [{ to: 'x' }, { cc: 'x' }] },
+      { operator: 'AND', conditions: [{ operator: 'OR', conditions: [{ hasKeyword: 'a' }, { body: 'x' }] }] },
+    ]) expect(filterHasTextTerms(filter), JSON.stringify(filter)).toBe(true);
+  });
+
+  it('is false when nothing is searched for', () => {
+    for (const filter of [
+      {}, { inMailbox: 'i' }, { hasKeyword: '$seen' }, { text: '' }, { text: '  ' },
+      { operator: 'AND', conditions: [{ inMailbox: 'i' }, { hasAttachment: true }] },
+      { operator: 'NOT', conditions: [{ text: 'x' }] },
+      { operator: 'AND', conditions: [] },
+    ]) expect(filterHasTextTerms(filter), JSON.stringify(filter)).toBe(false);
+  });
+});
+
+describe('through the client, with a real store', () => {
+  const SERVER = 'https://mail.example.org';
+  const SESSION = {
+    apiUrl: `${SERVER}/jmap/`,
+    downloadUrl: `${SERVER}/jmap/download/{accountId}/{blobId}/{name}?accept={type}`,
+    uploadUrl: `${SERVER}/jmap/upload/{accountId}/`,
+    accounts: { [JMAP_ACCOUNT]: { name: 'alice', isPersonal: true, accountCapabilities: {} } },
+    primaryAccounts: { 'urn:ietf:params:jmap:mail': JMAP_ACCOUNT },
+    capabilities: { 'urn:ietf:params:jmap:core': { maxObjectsInGet: 500 } },
+    username: 'alice@example.org',
+  };
+
+  let serverRows: Array<Record<string, unknown>>;
+  let serverFails: boolean;
+  let requests: Array<Array<[string, Record<string, unknown>, string]>>;
+
+  function fakeServerFetch() {
+    return vi.fn(async (url: string, init?: RequestInit) => {
+      if (String(url).endsWith('/.well-known/jmap')) return new Response(JSON.stringify(SESSION), { status: 200 });
+      const { methodCalls } = JSON.parse(String(init?.body)) as { methodCalls: Array<[string, Record<string, unknown>, string]> };
+      requests.push(methodCalls);
+      if (serverFails) return new Response('broken', { status: 500 });
+      const position = (methodCalls[0][1].position as number) ?? 0;
+      const limit = methodCalls[0][1].limit as number;
+      const page = serverRows.slice(position, position + limit);
+      return new Response(JSON.stringify({
+        methodResponses: methodCalls.map(([name, , id]) => {
+          if (name === 'Email/query') return [name, { ids: page.map((row) => row.id), total: serverRows.length, position }, id];
+          if (name === 'Email/get') return [name, { list: page, notFound: [] }, id];
+          return [name, { list: [], notFound: [] }, id];
+        }),
+      }), { status: 200 });
+    });
+  }
+
+  async function storeEngine() {
+    const fake = new FakeJmap();
+    fake.addEmail({ id: 'both', subject: 'Stromrechnung', receivedAt: '2026-10-05T00:00:00Z' });
+    fake.addEmail({ id: 'only-local', subject: 'Zahlungserinnerungsrechnung', receivedAt: '2026-10-03T00:00:00Z', mailboxIds: { inbox: true } });
+    fake.addEmail({ id: 'not-a-hit', subject: 'Hallo', receivedAt: '2026-10-02T00:00:00Z' });
+    const engine = new AccountEngine({
+      account: 'a@fake.test',
+      db: openMemoryStore(),
+      session: FAKE_SESSION,
+      transport: fake,
+      areas: [mailArea],
+      scope: { ...DEFAULT_SCOPE, days: null },
+      now: () => Date.UTC(2026, 10, 3),
+      sleep: async () => {},
+    });
+    await engine.requestSync();
+    return engine;
+  }
+
+  function hooksWith(searchLocal: OfflineHooks['searchLocal'], skipNetwork = false): OfflineHooks {
+    return {
+      skipNetwork: () => skipNetwork,
+      answer: async () => null,
+      record: () => {},
+      noteNetwork: () => {},
+      serverGone: async () => false,
+      blob: async () => null,
+      recordBlob: () => {},
+      holdUpload: async () => null,
+      searchLocal,
+    };
+  }
+
+  async function connected(): Promise<JMAPClient> {
+    const client = new JMAPClient(SERVER, 'alice@example.org', 'pw');
+    await client.connect();
+    return client;
+  }
+
+  beforeEach(() => {
+    serverFails = false;
+    requests = [];
+    serverRows = [
+      { id: 'newer', subject: 'Rechnung', receivedAt: '2026-10-06T00:00:00Z', mailboxIds: { inbox: true } },
+      { id: 'both', subject: 'Stromrechnung, server copy', receivedAt: '2026-10-05T00:00:00Z', mailboxIds: { inbox: true } },
+    ];
+    vi.stubGlobal('fetch', fakeServerFetch());
+    vi.spyOn(console, 'error').mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    setOfflineHooks(null);
+    vi.unstubAllGlobals();
+    vi.restoreAllMocks();
+  });
+
+  it('merges what the store finds into searchEmails, with its highlights', async () => {
+    const engine = await storeEngine();
+    setOfflineHooks(hooksWith((_client, calls) => engine.answer(calls)));
+    const client = await connected();
+    const result = await client.searchEmails('rechnung');
+    expect(result.emails.map((email) => email.id)).toEqual(['newer', 'both', 'only-local']);
+    expect(result.emails[1].subject).toBe('Stromrechnung, server copy');
+    expect(result.emails[2].searchSnippet?.subject).toBe('Zahlungserinnerungs<mark>rechnung</mark>');
+    expect(result.total).toBe(3);
+    expect(result.hasMore).toBe(false);
+  });
+
+  it('merges into advancedSearchEmails too, and leaves the server request as it was', async () => {
+    const engine = await storeEngine();
+    setOfflineHooks(hooksWith((_client, calls) => engine.answer(calls)));
+    const client = await connected();
+    const filter = { operator: 'AND', conditions: [{ inMailbox: 'inbox' }, { text: 'rechnung' }] };
+    const result = await client.advancedSearchEmails(filter);
+    expect(result.emails.map((email) => email.id)).toEqual(['newer', 'both', 'only-local']);
+    const query = requests[0][0];
+    expect(query[0]).toBe('Email/query');
+    expect(query[1]).toMatchObject({ filter, limit: 50, position: 0, calculateTotal: true, sort: [{ property: 'receivedAt', isAscending: false }] });
+  });
+
+  it('shows what the store found when the server fails', async () => {
+    const engine = await storeEngine();
+    setOfflineHooks(hooksWith((_client, calls) => engine.answer(calls)));
+    const client = await connected();
+    serverFails = true;
+    const result = await client.searchEmails('rechnung');
+    expect(result.emails.map((email) => email.id).sort()).toEqual(['both', 'only-local']);
+  });
+
+  it('shows what the server found when the store fails', async () => {
+    setOfflineHooks(hooksWith(async () => { throw new Error('store broke'); }));
+    const client = await connected();
+    const result = await client.searchEmails('rechnung');
+    expect(result.emails.map((email) => email.id)).toEqual(['newer', 'both']);
+  });
+
+  it('changes nothing when the store is off for the account', async () => {
+    const searchLocal = vi.fn(async () => null);
+    setOfflineHooks(hooksWith(searchLocal));
+    const client = await connected();
+    const result = await client.searchEmails('rechnung');
+    expect(searchLocal).toHaveBeenCalledTimes(1);
+    expect(result).toEqual({ emails: expect.any(Array), total: 2, hasMore: false });
+    expect(result.emails.map((email) => email.id)).toEqual(['newer', 'both']);
+    expect(requests.length).toBe(1);
+  });
+
+  it('changes nothing without a store', async () => {
+    setOfflineHooks(hooksWith(undefined));
+    const client = await connected();
+    const result = await client.searchEmails('rechnung', undefined, undefined, 50, 7);
+    expect(requests[0][0][1].position).toBe(7);
+    expect(result.total).toBe(2);
+  });
+
+  it('leaves filters without text to the server', async () => {
+    const searchLocal = vi.fn(async () => null);
+    setOfflineHooks(hooksWith(searchLocal));
+    const client = await connected();
+    await client.advancedSearchEmails({ inMailbox: 'inbox' });
+    await client.advancedSearchEmails({});
+    expect(searchLocal).not.toHaveBeenCalled();
+  });
+
+  it('does not ask twice when the device is answering anyway', async () => {
+    const searchLocal = vi.fn(async () => null);
+    const hooks = hooksWith(searchLocal, true);
+    hooks.answer = async (_client, calls) => ({
+      methodResponses: calls.map(([name, , id]) => (name === 'Email/query'
+        ? [name, { ids: [], total: 0, position: 0 }, id]
+        : [name, { list: [], notFound: [] }, id])),
+    });
+    setOfflineHooks(hooks);
+    const client = await connected();
+    await client.searchEmails('rechnung');
+    expect(searchLocal).not.toHaveBeenCalled();
+  });
+});
diff --git a/lib/jmap/client.ts b/lib/jmap/client.ts
index 6d35dcdfa..6563320f0 100644
--- a/lib/jmap/client.ts
+++ b/lib/jmap/client.ts
@@ -9,6 +9,7 @@ import type { SieveScript, SieveCapabilities } from "./sieve-types";
 import type { BlobBatch, CalendarEventUpdateOptions, CalendarQueryOptions, FileNodeListings, IJMAPClient, KeywordDiscoveryResult, KeywordInfo, KeywordMigration, SearchEmailsResult, SearchRequestOptions, UploadedEmailImport, UploadedEmailImportResult } from "./client-interface";
 import { attachSearchSnippets, filterHasSnippetTerms, snippetFilterFor, type SearchSnippetResult } from "@/lib/search-snippet";
 import { textConditions, textFilter } from "./search-utils";
+import { filterHasTextTerms, LocalSearchMerge } from "./search-merge";
 import { batched, batchedBySize, itemsPerRequest } from "./request-limits";
 import { keywordPointer, pointerToken } from "./patch-pointer";
 import { FirstTouchGate } from "./first-touch-gate";
@@ -1638,6 +1639,7 @@ export class JMAPClient implements IJMAPClient {
    * can be reached again (a reload signs in as usual).
    */
   private offlineOnly = false;
+  private readonly searchMerge = new LocalSearchMerge();
 
   constructor(serverUrl: string, username: string, password: string) {
     this.serverUrl = serverUrl.replace(/\/$/, '');
@@ -4392,61 +4394,111 @@ export class JMAPClient implements IJMAPClient {
   }
 
   async searchEmails(query: string, mailboxId?: string, accountId?: string, limit: number = 50, position: number = 0, options: SearchRequestOptions = {}): Promise<SearchEmailsResult> {
+    // The JMAP "text" filter searches from, to, cc, bcc, subject and body.
+    // Quoted phrases and `word*` prefixes go out as conditions of their
+    // own (see splitSearchText). inMailbox joins them in the same AND: a
+    // FilterOperator cannot also carry property keys.
+    const filter: Record<string, unknown> = mailboxId
+      ? { operator: "AND", conditions: [{ inMailbox: mailboxId }, ...textConditions(query)] }
+      : textFilter(query);
+    return this.searchWithLocal(filter, accountId, limit, position, options);
+  }
+
+  /**
+   * A search on the server, merged with what the local store finds (see
+   * search-merge.ts). Without a store for this client, or when the request
+   * would be answered on this device anyway, it's the server's answer alone.
+   */
+  private searchWithLocal(
+    filter: Record<string, unknown>,
+    accountId: string | undefined,
+    limit: number,
+    position: number,
+    options: SearchRequestOptions,
+  ): Promise<SearchEmailsResult> {
+    const server = (at: number) => this.serverSearch(filter, accountId, limit, at, options);
+    const hooks = getOfflineHooks();
+    const searchLocal = hooks?.searchLocal;
+    if (!searchLocal || this.offlineOnly || hooks.skipNetwork(this) || !filterHasTextTerms(filter)) {
+      return server(position);
+    }
+    return this.searchMerge.run({
+      key: JSON.stringify([accountId ?? null, filter]),
+      limit,
+      position,
+      server,
+      local: async (at) => {
+        const targetAccountId = accountId || this.accountId;
+        const answer = await searchLocal.call(hooks, this, this.searchCalls(targetAccountId, filter, limit, at, false));
+        return answer ? this.searchResultFrom(answer as JMAPResponse, accountId, limit, at) : null;
+      },
+    });
+  }
+
+  private searchCalls(
+    targetAccountId: string,
+    filter: Record<string, unknown>,
+    limit: number,
+    position: number,
+    deferSnippets: boolean | undefined,
+  ): JMAPMethodCall[] {
+    // Searching all folders with no criteria yields an empty FilterCondition,
+    // which servers reject; omit the key entirely to mean "no filter".
+    const hasFilter = Object.keys(filter).length > 0;
+    return [
+      ["Email/query", {
+        accountId: targetAccountId,
+        ...(hasFilter ? { filter } : {}),
+        sort: [{ property: "receivedAt", isAscending: false }],
+        limit,
+        position,
+        calculateTotal: true,
+      }, "0"],
+      ["Email/get", {
+        accountId: targetAccountId,
+        "#ids": { resultOf: "0", name: "Email/query", path: "/ids" },
+        properties: [...EMAIL_LIST_PROPERTIES],
+      }, "1"],
+      ...(deferSnippets ? [] : [this.searchSnippetCall(targetAccountId, hasFilter ? filter : undefined)]),
+    ];
+  }
+
+  private searchResultFrom(response: JMAPResponse, accountId: string | undefined, limit: number, position: number): SearchEmailsResult {
+    assertQuerySucceeded(response, 'Search');
+
+    const queryResponse = response.methodResponses?.[0]?.[1];
+    const emails = applyListAuthenticationResults((response.methodResponses?.[1]?.[1]?.list || []) as Email[]);
+    emails.sort((a: Email, b: Email) =>
+      new Date(b.receivedAt).getTime() - new Date(a.receivedAt).getTime()
+    );
+    const total = queryResponse?.total || 0;
+    const hasMore = computeHasMore(position, emails.length, total, limit);
+    attachSearchSnippets(emails, this.searchSnippetsFrom(response));
+
+    // Mirror getEmails: emails fetched from a delegated/shared account carry
+    // bare owner mailbox ids; namespace them to `${ownerId}:${id}` so they line
+    // up with the namespaced ids the store holds for shared mailboxes. The
+    // cross-account views (All mail / Unread / Starred) browse via
+    // advancedSearchEmails, so they need this too. (#281 V3)
+    if (accountId && accountId !== this.accountId) {
+      namespaceMailboxIds(emails, accountId);
+    }
+    return { emails, hasMore, total };
+  }
+
+  private async serverSearch(
+    filter: Record<string, unknown>,
+    accountId: string | undefined,
+    limit: number,
+    position: number,
+    options: SearchRequestOptions,
+  ): Promise<SearchEmailsResult> {
     try {
       const targetAccountId = accountId || this.accountId;
-
-      // The JMAP "text" filter searches from, to, cc, bcc, subject and body.
-      // Quoted phrases and `word*` prefixes go out as conditions of their
-      // own (see splitSearchText). inMailbox joins them in the same AND: a
-      // FilterOperator cannot also carry property keys.
-      let filter: Record<string, unknown>;
-      if (mailboxId) {
-        filter = {
-          operator: "AND",
-          conditions: [
-            { inMailbox: mailboxId },
-            ...textConditions(query),
-          ],
-        };
-      } else {
-        filter = textFilter(query);
-      }
-
-      const response = await this.request([
-        ["Email/query", {
-          accountId: targetAccountId,
-          filter,
-          sort: [{ property: "receivedAt", isAscending: false }],
-          limit,
-          position,
-          calculateTotal: true,
-        }, "0"],
-        ["Email/get", {
-          accountId: targetAccountId,
-          "#ids": { resultOf: "0", name: "Email/query", path: "/ids" },
-          properties: [...EMAIL_LIST_PROPERTIES],
-        }, "1"],
-        ...(options.deferSnippets ? [] : [this.searchSnippetCall(targetAccountId, filter)]),
-      ]);
-      assertQuerySucceeded(response, 'Search');
-
-      const queryResponse = response.methodResponses?.[0]?.[1];
-      const emails = applyListAuthenticationResults((response.methodResponses?.[1]?.[1]?.list || []) as Email[]);
-      emails.sort((a: Email, b: Email) =>
-        new Date(b.receivedAt).getTime() - new Date(a.receivedAt).getTime()
-      );
-      const total = queryResponse?.total || 0;
-      const hasMore = computeHasMore(position, emails.length, total, limit);
-      attachSearchSnippets(emails, this.searchSnippetsFrom(response));
-
-      // Mirror getEmails: emails fetched from a delegated/shared account carry
-      // bare owner mailbox ids; namespace them to `${ownerId}:${id}` so they line
-      // up with the namespaced ids the store holds for shared mailboxes. (#281 V3)
-      if (accountId && accountId !== this.accountId) {
-        namespaceMailboxIds(emails, accountId);
-      }
-
-      return { emails, hasMore, total, ...this.deferredSnippets(options, targetAccountId, filter, emails) };
+      const hasFilter = Object.keys(filter).length > 0;
+      const response = await this.request(this.searchCalls(targetAccountId, filter, limit, position, options.deferSnippets));
+      const result = this.searchResultFrom(response, accountId, limit, position);
+      return { ...result, ...this.deferredSnippets(options, targetAccountId, hasFilter ? filter : undefined, result.emails) };
     } catch (error) {
       // Rethrow: an empty result would read as "No results found".
       console.error('Search failed:', error);
@@ -4518,52 +4570,7 @@ export class JMAPClient implements IJMAPClient {
     position: number = 0,
     options: SearchRequestOptions = {},
   ): Promise<SearchEmailsResult> {
-    try {
-      const targetAccountId = accountId || this.accountId;
-
-      // Searching all folders with no criteria yields an empty FilterCondition,
-      // which servers reject; omit the key entirely to mean "no filter".
-      const hasFilter = Object.keys(filter).length > 0;
-
-      const response = await this.request([
-        ["Email/query", {
-          accountId: targetAccountId,
-          ...(hasFilter ? { filter } : {}),
-          sort: [{ property: "receivedAt", isAscending: false }],
-          limit,
-          position,
-          calculateTotal: true,
-        }, "0"],
-        ["Email/get", {
-          accountId: targetAccountId,
-          "#ids": { resultOf: "0", name: "Email/query", path: "/ids" },
-          properties: [...EMAIL_LIST_PROPERTIES],
-        }, "1"],
-        ...(options.deferSnippets ? [] : [this.searchSnippetCall(targetAccountId, hasFilter ? filter : undefined)]),
-      ]);
-      assertQuerySucceeded(response, 'Search');
-
-      const queryResponse = response.methodResponses?.[0]?.[1];
-      const emails = applyListAuthenticationResults((response.methodResponses?.[1]?.[1]?.list || []) as Email[]);
-      emails.sort((a: Email, b: Email) =>
-        new Date(b.receivedAt).getTime() - new Date(a.receivedAt).getTime()
-      );
-      const total = queryResponse?.total || 0;
-      const hasMore = computeHasMore(position, emails.length, total, limit);
-      attachSearchSnippets(emails, this.searchSnippetsFrom(response));
-
-      // Namespace shared/delegated-account mailbox ids (see searchEmails). The
-      // cross-account views (All mail / Unread / Starred) browse via this method,
-      // so without it shared emails would carry bare owner ids there. (#281 V3)
-      if (accountId && accountId !== this.accountId) {
-        namespaceMailboxIds(emails, accountId);
-      }
-
-      return { emails, hasMore, total, ...this.deferredSnippets(options, targetAccountId, hasFilter ? filter : undefined, emails) };
-    } catch (error) {
-      console.error('Advanced search failed:', error);
-      throw error;
-    }
+    return this.searchWithLocal(filter, accountId, limit, position, options);
   }
 
   async getEmailFields(
diff --git a/lib/jmap/offline-hooks.ts b/lib/jmap/offline-hooks.ts
index ab0477fc9..b96dc1818 100644
--- a/lib/jmap/offline-hooks.ts
+++ b/lib/jmap/offline-hooks.ts
@@ -45,6 +45,12 @@ export interface OfflineHooks {
   recordBlob(client: OfflineClientRef, blobId: string, accountId: string, blob: Blob): void;
   /** Keep a file to upload later; the stand-in blob id, or null when offline mode doesn't cover the client. */
   holdUpload(client: OfflineClientRef, file: File, accountId: string): Promise<{ blobId: string; size: number; type: string } | null>;
+  /**
+   * Search calls answered from the local store while the server is asked too
+   * (lib/jmap/search-merge.ts). Null when the store doesn't cover the client.
+   * Left out when there is no store, and searches then go to the server alone.
+   */
+  searchLocal?(client: OfflineClientRef, methodCalls: OfflineMethodCall[]): Promise<OfflineResponse | null>;
 }
 
 const KEY = '__bulwarkOfflineHooks';
diff --git a/lib/jmap/search-merge.ts b/lib/jmap/search-merge.ts
new file mode 100644
index 000000000..a38cb53d1
--- /dev/null
+++ b/lib/jmap/search-merge.ts
@@ -0,0 +1,203 @@
+/**
+ * Online, a search also asks the local store and merges the two answers. The
+ * store finds what the server's index can't, such as a word inside a German
+ * compound. This module knows nothing about the store: it merges two lists.
+ *
+ * The merge walks both lists newest first, as a search sorts them. When both
+ * have a message, the server's copy is kept. A page never holds more than
+ * `limit` rows, so a local row can push a server row to the next page.
+ *
+ * Callers page by counting the rows they have, so `position` counts merged
+ * rows and means nothing to the server once a local row is among them. A cursor
+ * for each search remembers how far each side was read. A request past 0 with
+ * no cursor goes to the server alone, exactly as it would without a store.
+ *
+ * `hasMore` is true while either side has rows this search hasn't returned.
+ * A local list made only of rows the server also has can therefore cost one
+ * extra page that comes back empty, and then it's false.
+ *
+ * `total` is the server's total plus the local-only rows returned so far, and
+ * never less than the local total or the rows already returned. It can grow
+ * while paging, because how many local rows the server also has only shows
+ * when the lists are read.
+ *
+ * Local rows older than the last row the server sent wait for the next page:
+ * they may still be on the server's next page.
+ *
+ * An error on one side keeps the other side's rows. When the server fails and
+ * the store has nothing, the server's error stands, since an empty list would
+ * read as "no results". A slow store never holds up the server's answer for
+ * longer than LOCAL_GRACE_MS.
+ */
+
+import { debug } from '@/lib/debug';
+import type { SearchEmailsResult } from './client-interface';
+import type { Email } from './types';
+
+const LOCAL_GRACE_MS = 1_000;
+const LOCAL_ALONE_MS = 5_000;
+const MAX_CURSORS = 8;
+
+const TEXT_FILTER_KEYS = ['text', 'from', 'to', 'cc', 'bcc', 'subject', 'body'];
+
+/**
+ * Whether a filter searches for text. Other filters (a folder, a flag, a date)
+ * have the same answer on both sides, so only a stale local row could come of
+ * merging them. Terms under NOT are searched to be absent, so they don't count.
+ */
+export function filterHasTextTerms(filter: Record<string, unknown>): boolean {
+  if (typeof filter.operator === 'string') {
+    if (filter.operator === 'NOT' || !Array.isArray(filter.conditions)) return false;
+    return (filter.conditions as Array<Record<string, unknown>>).some(filterHasTextTerms);
+  }
+  return TEXT_FILTER_KEYS.some((key) => typeof filter[key] === 'string' && (filter[key] as string).trim().length > 0);
+}
+
+interface MergeCursor {
+  /** Merged rows returned so far, which is where the next page should ask from. */
+  next: number;
+  serverPosition: number;
+  localPosition: number;
+  serverTotal: number;
+  /** Local-only rows returned so far. */
+  extras: number;
+  /** Every row returned so far, so none appears twice. */
+  shown: Set<string>;
+}
+
+function receivedTime(email: Email): number {
+  return Date.parse(email.receivedAt) || 0;
+}
+
+interface PageMerge {
+  emails: Email[];
+  serverRead: number;
+  localRead: number;
+  extras: number;
+}
+
+/** One merged page. Rows are added to `shown`. */
+export function mergeSearchPages(
+  server: readonly Email[],
+  serverHasMore: boolean,
+  local: readonly Email[],
+  limit: number,
+  shown: Set<string>,
+): PageMerge {
+  const serverIds = new Set(server.map((email) => email.id));
+  const emails: Email[] = [];
+  let s = 0;
+  let l = 0;
+  let extras = 0;
+  while (emails.length < limit) {
+    const fromServer = server[s];
+    const fromLocal = local[l];
+    if (fromLocal && (serverIds.has(fromLocal.id) || shown.has(fromLocal.id))) {
+      l += 1;
+      continue;
+    }
+    if (fromServer && shown.has(fromServer.id)) {
+      s += 1;
+      continue;
+    }
+    if (!fromServer && (!fromLocal || serverHasMore)) break;
+    if (fromServer && (!fromLocal || receivedTime(fromLocal) <= receivedTime(fromServer))) {
+      emails.push(fromServer);
+      shown.add(fromServer.id);
+      s += 1;
+    } else {
+      emails.push(fromLocal);
+      shown.add(fromLocal.id);
+      l += 1;
+      extras += 1;
+    }
+  }
+  return { emails, serverRead: s, localRead: l, extras };
+}
+
+/** The promise's value, or null if it fails or takes longer than `ms`. */
+function within<T>(promise: Promise<T | null>, ms: number): Promise<T | null> {
+  return new Promise((resolve) => {
+    const timer = setTimeout(() => resolve(null), ms);
+    promise.then(
+      (value) => {
+        clearTimeout(timer);
+        resolve(value);
+      },
+      (error) => {
+        clearTimeout(timer);
+        debug.warn('jmap', 'Local search failed:', error);
+        resolve(null);
+      },
+    );
+  });
+}
+
+export interface MergedSearchRequest {
+  /** The same for every page of one search. */
+  key: string;
+  limit: number;
+  position: number;
+  server(position: number): Promise<SearchEmailsResult>;
+  /** Null when the store doesn't cover this account. */
+  local(position: number): Promise<SearchEmailsResult | null>;
+}
+
+export class LocalSearchMerge {
+  private readonly cursors = new Map<string, MergeCursor>();
+
+  private startCursor(key: string): MergeCursor {
+    const cursor: MergeCursor = { next: 0, serverPosition: 0, localPosition: 0, serverTotal: 0, extras: 0, shown: new Set() };
+    this.cursors.delete(key);
+    this.cursors.set(key, cursor);
+    if (this.cursors.size > MAX_CURSORS) this.cursors.delete(this.cursors.keys().next().value as string);
+    return cursor;
+  }
+
+  async run(request: MergedSearchRequest): Promise<SearchEmailsResult> {
+    const { key, limit, position } = request;
+    const cursor = position === 0 ? this.startCursor(key) : this.cursors.get(key);
+    if (!cursor) return request.server(position);
+
+    // A caller that removed rows or added its own asks from a little off
+    // where the last page ended, and the server's side moves with it.
+    const serverPosition = Math.max(0, cursor.serverPosition + position - cursor.next);
+    const localAnswer = Promise.resolve().then(() => request.local(cursor.localPosition));
+
+    let serverPage: SearchEmailsResult | null = null;
+    let serverError: unknown = null;
+    try {
+      serverPage = await request.server(serverPosition);
+    } catch (error) {
+      serverError = error;
+    }
+    const localPage = await within(localAnswer, serverPage ? LOCAL_GRACE_MS : LOCAL_ALONE_MS);
+
+    if (!serverPage && !localPage?.emails.length) throw serverError;
+    if (serverPage && !localPage && cursor.extras === 0) {
+      // Nothing local in this search: the server's answer, untouched.
+      this.cursors.delete(key);
+      return serverPage;
+    }
+
+    const server = serverPage?.emails ?? [];
+    const serverHasMore = serverPage?.hasMore ?? false;
+    const local = localPage?.emails ?? [];
+    const merged = mergeSearchPages(server, serverHasMore, local, limit, cursor.shown);
+
+    cursor.serverPosition = serverPosition + merged.serverRead;
+    cursor.localPosition += merged.localRead;
+    cursor.next = position + merged.emails.length;
+    cursor.extras += merged.extras;
+    if (serverPage) cursor.serverTotal = serverPage.total;
+
+    const serverLeft = merged.serverRead < server.length || serverHasMore;
+    const localLeft = localPage ? merged.localRead < local.length || localPage.hasMore : false;
+    return {
+      ...serverPage,
+      emails: merged.emails,
+      hasMore: serverLeft || localLeft,
+      total: Math.max(cursor.serverTotal + cursor.extras, localPage?.total ?? 0, cursor.next),
+    };
+  }
+}