diff --git a/lib/online-backup-manager.js b/lib/online-backup-manager.js
new file mode 100644
index 0000000..17723c9
--- /dev/null
+++ b/lib/online-backup-manager.js
@@ -0,0 +1,112 @@
+const {
+  createOnlineBackup,
+  deleteOnlineBackup,
+  uploadOnlineBackup
+} = require('./online-backup');
+
+const ERRORS = Object.freeze({
+  list: 'Online-Sicherungen konnten nicht geladen werden',
+  create: 'Online-Sicherung konnte nicht erstellt werden',
+  copy: 'Online-Sicherungsschlüssel konnte nicht kopiert werden',
+  delete: 'Online-Sicherung konnte nicht gelöscht werden',
+  notFound: 'Online-Sicherungsschlüssel wurde nicht gefunden'
+});
+
+function sanitizeEntry(entry) {
+  return {
+    id: entry.id,
+    displayKey: entry.displayKey,
+    createdAt: entry.createdAt
+  };
+}
+
+function createOnlineBackupManager({
+  keyring,
+  loadSettings,
+  appVersion,
+  createBackup = createOnlineBackup,
+  uploadBackup = uploadOnlineBackup,
+  deleteBackup = deleteOnlineBackup,
+  copyText
+}) {
+  let mutation = Promise.resolve();
+
+  function serialize(operation) {
+    const next = mutation.catch(() => {}).then(operation);
+    mutation = next;
+    return next;
+  }
+
+  async function listEntries() {
+    const entries = await keyring.list();
+    return entries.map(sanitizeEntry);
+  }
+
+  async function createTransaction() {
+    const createdAt = new Date().toISOString();
+    const settings = await loadSettings();
+    const created = createBackup(settings, appVersion(), createdAt);
+    const prepared = keyring.prepare(created.key, createdAt);
+    await uploadBackup(created.record);
+    try {
+      await keyring.commit(prepared);
+    } catch (error) {
+      try {
+        await deleteBackup(created.key);
+      } catch {}
+      throw error;
+    }
+    const entries = await listEntries();
+    const entry = entries.find((current) => current.id === prepared.id);
+    if (!entry) throw new Error(ERRORS.create);
+    return { ok: true, entry };
+  }
+
+  async function deleteTransaction(id) {
+    const key = await keyring.getKey(id);
+    if (!key) return { ok: false, notFound: true, error: ERRORS.notFound };
+    const outcome = await deleteBackup(key);
+    if (!outcome?.deleted && !outcome?.notFound) throw new Error(ERRORS.delete);
+    await keyring.remove(id);
+    return { ok: true, removedId: id, notFound: outcome.notFound };
+  }
+
+  async function listManaged() {
+    try {
+      return { ok: true, entries: await listEntries() };
+    } catch {
+      return { ok: false, error: ERRORS.list };
+    }
+  }
+
+  async function createManaged() {
+    try {
+      return await serialize(createTransaction);
+    } catch {
+      return { ok: false, error: ERRORS.create };
+    }
+  }
+
+  async function copyManaged(id) {
+    try {
+      const key = await keyring.getKey(id);
+      if (!key) return { ok: false, notFound: true, error: ERRORS.notFound };
+      await copyText(key);
+      return { ok: true };
+    } catch {
+      return { ok: false, error: ERRORS.copy };
+    }
+  }
+
+  async function deleteManaged(id) {
+    try {
+      return await serialize(() => deleteTransaction(id));
+    } catch {
+      return { ok: false, error: ERRORS.delete };
+    }
+  }
+
+  return Object.freeze({ listManaged, createManaged, copyManaged, deleteManaged });
+}
+
+module.exports = { createOnlineBackupManager };
diff --git a/tests/online-backup-manager.test.js b/tests/online-backup-manager.test.js
new file mode 100644
index 0000000..ca6c52d
--- /dev/null
+++ b/tests/online-backup-manager.test.js
@@ -0,0 +1,290 @@
+const { describe, it } = require('node:test');
+const assert = require('node:assert/strict');
+
+const { createOnlineBackupManager } = require('../lib/online-backup-manager');
+
+const key = `MHU2-${'K'.repeat(70)}`;
+const id = 'managed-backup-id';
+const record = { id, blob: 'encrypted-blob', deleteVerifier: 'delete-verifier' };
+const settings = { globalSettings: { alwaysOnTop: true } };
+
+function createFixture(overrides = {}) {
+  const events = [];
+  const state = new Map();
+  const entries = new Map();
+  if (overrides.initialKey !== null) {
+    state.set(id, overrides.initialKey || key);
+    entries.set(id, {
+      id,
+      displayKey: `${key.slice(0, 9)}…${key.slice(-4)}`,
+      createdAt: '2026-08-22T10:00:00.000Z'
+    });
+  }
+  let createdAt;
+  let createArguments;
+  const keyring = {
+    list: async () => {
+      events.push('list');
+      return [...entries.values()];
+    },
+    prepare: (value, timestamp) => {
+      events.push('prepare');
+      if (overrides.prepareError) throw overrides.prepareError;
+      createdAt = timestamp;
+      return { id, encryptedKey: 'encrypted-key', createdAt: timestamp };
+    },
+    commit: async (entry) => {
+      events.push('commit');
+      if (overrides.commitError) throw overrides.commitError;
+      state.set(entry.id, key);
+      entries.set(entry.id, {
+        id: entry.id,
+        displayKey: `${key.slice(0, 9)}…${key.slice(-4)}`,
+        createdAt: entry.createdAt
+      });
+    },
+    remove: async (entryId) => {
+      events.push('remove');
+      const existed = state.delete(entryId);
+      entries.delete(entryId);
+      return existed;
+    },
+    getKey: async (entryId) => {
+      events.push('getKey');
+      return state.get(entryId) || null;
+    }
+  };
+  const manager = createOnlineBackupManager({
+    keyring,
+    loadSettings: async () => settings,
+    appVersion: () => '2.1.31',
+    createBackup: (...args) => {
+      createArguments = args;
+      return { key, record };
+    },
+    uploadBackup: async (uploadedRecord) => {
+      events.push('upload');
+      assert.equal(uploadedRecord, record);
+      if (overrides.uploadError) throw overrides.uploadError;
+    },
+    deleteBackup: async (value) => {
+      events.push(`delete:${value}`);
+      if (overrides.deleteError) throw overrides.deleteError;
+      return overrides.deletionOutcome || { deleted: true, notFound: false };
+    },
+    copyText: (value) => events.push(`copy:${value}`)
+  });
+  return {
+    events,
+    keyring,
+    manager,
+    state,
+    get createdAt() {
+      return createdAt;
+    },
+    get createArguments() {
+      return createArguments;
+    }
+  };
+}
+
+describe('transactional online backup manager', () => {
+  it('creates in prepare, upload, commit order and returns only the sanitized entry', async () => {
+    const fixture = createFixture({ initialKey: null });
+
+    const result = await fixture.manager.createManaged();
+
+    assert.deepEqual(fixture.events, ['prepare', 'upload', 'commit', 'list']);
+    assert.deepEqual(fixture.createArguments, [settings, '2.1.31', fixture.createdAt]);
+    assert.match(fixture.createdAt, /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}Z$/);
+    assert.deepEqual(result, {
+      ok: true,
+      entry: {
+        id,
+        displayKey: `${key.slice(0, 9)}…${key.slice(-4)}`,
+        createdAt: fixture.createdAt
+      }
+    });
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('does not upload when preparing encrypted local state fails', async () => {
+    const fixture = createFixture({
+      initialKey: null,
+      prepareError: new Error(`prepare failed with ${key}`)
+    });
+
+    const result = await fixture.manager.createManaged();
+
+    assert.deepEqual(fixture.events, ['prepare']);
+    assert.deepEqual(result, { ok: false, error: 'Online-Sicherung konnte nicht erstellt werden' });
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('does not commit when the upload fails', async () => {
+    const fixture = createFixture({
+      initialKey: null,
+      uploadError: new Error(`upload failed with ${key}`)
+    });
+
+    const result = await fixture.manager.createManaged();
+
+    assert.deepEqual(fixture.events, ['prepare', 'upload']);
+    assert.deepEqual(result, { ok: false, error: 'Online-Sicherung konnte nicht erstellt werden' });
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('rolls the remote backup back with the in-memory key when commit fails', async () => {
+    const fixture = createFixture({
+      initialKey: null,
+      commitError: new Error(`commit failed with ${key}`)
+    });
+
+    const result = await fixture.manager.createManaged();
+
+    assert.deepEqual(fixture.events, ['prepare', 'upload', 'commit', `delete:${key}`]);
+    assert.deepEqual(result, { ok: false, error: 'Online-Sicherung konnte nicht erstellt werden' });
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('keeps a commit failure sanitized when best-effort rollback also fails', async () => {
+    const fixture = createFixture({
+      initialKey: null,
+      commitError: new Error(`commit failed with ${key}`),
+      deleteError: new Error(`rollback failed with ${key}`)
+    });
+
+    const result = await fixture.manager.createManaged();
+
+    assert.deepEqual(fixture.events, ['prepare', 'upload', 'commit', `delete:${key}`]);
+    assert.deepEqual(result, { ok: false, error: 'Online-Sicherung konnte nicht erstellt werden' });
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('decrypts a managed key only inside copy and returns no key', async () => {
+    const fixture = createFixture();
+
+    const result = await fixture.manager.copyManaged(id);
+
+    assert.deepEqual(fixture.events, ['getKey', `copy:${key}`]);
+    assert.deepEqual(result, { ok: true });
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('removes the local entry after a successful remote deletion', async () => {
+    const fixture = createFixture();
+
+    const result = await fixture.manager.deleteManaged(id);
+
+    assert.deepEqual(fixture.events, ['getKey', `delete:${key}`, 'remove']);
+    assert.deepEqual(result, { ok: true, removedId: id, notFound: false });
+    assert.equal(fixture.state.has(id), false);
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('removes a stale local entry and reports a missing remote backup', async () => {
+    const fixture = createFixture({ deletionOutcome: { deleted: false, notFound: true } });
+
+    const result = await fixture.manager.deleteManaged(id);
+
+    assert.deepEqual(fixture.events, ['getKey', `delete:${key}`, 'remove']);
+    assert.deepEqual(result, { ok: true, removedId: id, notFound: true });
+    assert.equal(fixture.state.has(id), false);
+  });
+
+  it('keeps the local entry when remote deletion fails', async () => {
+    const fixture = createFixture({ deleteError: new Error(`network failed with ${key}`) });
+
+    const result = await fixture.manager.deleteManaged(id);
+
+    assert.deepEqual(fixture.events, ['getKey', `delete:${key}`]);
+    assert.deepEqual(result, { ok: false, error: 'Online-Sicherung konnte nicht gelöscht werden' });
+    assert.equal(fixture.state.has(id), true);
+    assert.equal(JSON.stringify(result).includes(key), false);
+  });
+
+  it('does not call copy or remote deletion dependencies for unknown IDs', async () => {
+    const fixture = createFixture({ initialKey: null });
+
+    const copied = await fixture.manager.copyManaged('unknown-id');
+    const deleted = await fixture.manager.deleteManaged('unknown-id');
+
+    assert.deepEqual(fixture.events, ['getKey', 'getKey']);
+    assert.deepEqual(copied, {
+      ok: false,
+      notFound: true,
+      error: 'Online-Sicherungsschlüssel wurde nicht gefunden'
+    });
+    assert.deepEqual(deleted, {
+      ok: false,
+      notFound: true,
+      error: 'Online-Sicherungsschlüssel wurde nicht gefunden'
+    });
+  });
+
+  it('serializes concurrent create and delete mutations in request order', async () => {
+    const fixture = createFixture({ initialKey: null });
+    let releaseUpload;
+    fixture.manager = createOnlineBackupManager({
+      keyring: fixture.keyring,
+      loadSettings: async () => settings,
+      appVersion: () => '2.1.31',
+      createBackup: (_settings, _version, exportedAt) => {
+        fixture.createdTimestamp = exportedAt;
+        return { key, record };
+      },
+      uploadBackup: async () => {
+        fixture.events.push('upload:start');
+        await new Promise((resolve) => {
+          releaseUpload = resolve;
+        });
+        fixture.events.push('upload:end');
+      },
+      deleteBackup: async (value) => {
+        fixture.events.push(`delete:${value}`);
+        return { deleted: true, notFound: false };
+      },
+      copyText: () => {}
+    });
+
+    const creating = fixture.manager.createManaged();
+    const deleting = fixture.manager.deleteManaged(id);
+    await new Promise((resolve) => setImmediate(resolve));
+
+    assert.deepEqual(fixture.events, ['prepare', 'upload:start']);
+    releaseUpload();
+    const [created, deleted] = await Promise.all([creating, deleting]);
+
+    assert.equal(created.ok, true);
+    assert.deepEqual(deleted, { ok: true, removedId: id, notFound: false });
+    assert.deepEqual(fixture.events, [
+      'prepare',
+      'upload:start',
+      'upload:end',
+      'commit',
+      'list',
+      'getKey',
+      `delete:${key}`,
+      'remove'
+    ]);
+  });
+
+  it('lists sanitized entries and contains dependency failures at the public boundary', async () => {
+    const fixture = createFixture();
+
+    assert.deepEqual(await fixture.manager.listManaged(), {
+      ok: true,
+      entries: [{
+        id,
+        displayKey: `${key.slice(0, 9)}…${key.slice(-4)}`,
+        createdAt: '2026-08-22T10:00:00.000Z'
+      }]
+    });
+    fixture.keyring.list = async () => {
+      throw new Error(`list failed with ${key}`);
+    };
+    const failed = await fixture.manager.listManaged();
+    assert.deepEqual(failed, { ok: false, error: 'Online-Sicherungen konnten nicht geladen werden' });
+    assert.equal(JSON.stringify(failed).includes(key), false);
+  });
+});