diff --git a/lib/__tests__/plugin-assistant-areas.test.ts b/lib/__tests__/plugin-assistant-areas.test.ts
new file mode 100644
index 000000000..2574cd39c
--- /dev/null
+++ b/lib/__tests__/plugin-assistant-areas.test.ts
@@ -0,0 +1,59 @@
+import { describe, expect, it, vi } from 'vitest';
+
+// The AI assistant's host APIs live in one set of files per area
+// (lib/plugin-sandbox/assistant). These tests check that whatever an area
+// adds reaches the permission table, the dispatcher, api.host.features and
+// the plugin's api, without the shared files naming it.
+
+vi.mock('@/stores/toast-store', () => ({
+  toast: { success: vi.fn(), error: vi.fn(), info: vi.fn(), warning: vi.fn() },
+}));
+
+const area = vi.hoisted(() => ({
+  calls: [] as unknown[][],
+}));
+
+vi.mock('@/lib/plugin-sandbox/assistant/b', () => ({
+  PERMS: { 'email.probeArea': 'email:read' },
+  dispatch: async (_plugin: unknown, method: string, args: unknown[]) => { area.calls.push([method, ...args]); return 'from area b'; },
+  features: () => ({ probeArea: true }),
+}));
+
+vi.mock('@/lib/plugin-sandbox/assistant/b.runtime', () => ({
+  runtime: (callApi: (m: string, a: unknown[]) => Promise<unknown>) => ({ email: { probeArea: (x: string) => callApi('email.probeArea', [x]) } }),
+}));
+
+const { PERM_PER_METHOD, dispatchApiCall } = await import('@/lib/plugin-sandbox/host-api');
+const { snapshotHostFeatures } = await import('@/lib/plugin-sandbox/host-features');
+const { withAssistantRuntime } = await import('@/lib/plugin-sandbox/assistant/runtime');
+const { NOT_MINE, dispatchAssistant } = await import('@/lib/plugin-sandbox/assistant');
+
+const plugin = { id: 'p', name: 'P', permissions: ['email:read'], managed: true } as never;
+
+describe('the assistant areas', () => {
+  it('put their methods behind their permissions and run them', async () => {
+    expect(PERM_PER_METHOD['email.probeArea']).toBe('email:read');
+    expect(await dispatchApiCall(plugin, 'email.probeArea', ['x'])).toBe('from area b');
+    expect(area.calls).toEqual([['email.probeArea', 'x']]);
+    // Without the permission the area never sees the call.
+    const without = { ...(plugin as object), permissions: [] } as never;
+    await expect(dispatchApiCall(without, 'email.probeArea', [])).rejects.toThrow(/lacks permission "email:read"/);
+    expect(area.calls).toHaveLength(1);
+  });
+
+  it('leave other methods alone', async () => {
+    expect(await dispatchAssistant(plugin, 'email.get', [])).toBe(NOT_MINE);
+  });
+
+  it('add their flags to api.host.features', () => {
+    expect(snapshotHostFeatures()).toMatchObject({ probeArea: true, externalSenderLabel: false });
+  });
+
+  it('add their methods to the plugin api next to the existing ones', () => {
+    const calls: unknown[][] = [];
+    const api = withAssistantRuntime({ email: { get: () => 'core' } }, async (method, args) => { calls.push([method, args]); return null; });
+    expect(api.email.get()).toBe('core');
+    (api.email as unknown as { probeArea: (x: string) => unknown }).probeArea('y');
+    expect(calls).toEqual([['email.probeArea', ['y']]]);
+  });
+});
diff --git a/lib/__tests__/plugin-host-features.test.ts b/lib/__tests__/plugin-host-features.test.ts
index 5c76a65d5..9e0dc0abf 100644
--- a/lib/__tests__/plugin-host-features.test.ts
+++ b/lib/__tests__/plugin-host-features.test.ts
@@ -17,6 +17,10 @@ import {
   isSlotHandedOver,
   snapshotHostFeatures,
 } from '@/lib/plugin-sandbox/host-features';
+import { assistantFeatures } from '@/lib/plugin-sandbox/assistant';
+
+/** The AI assistant's flags (lib/plugin-sandbox/assistant) come on top; their own tests check them. */
+const withAssistant = (core: Record<string, boolean>) => ({ ...core, ...assistantFeatures() });
 
 function setExternalMail(patch: Partial<typeof DEFAULT_ORGANISATION_POLICY.externalMail>) {
   usePolicyStore.setState({
@@ -31,11 +35,11 @@ beforeEach(() => setExternalMail({}));
 
 describe('snapshotHostFeatures', () => {
   it('has one flag per switch', () => {
-    expect(snapshotHostFeatures()).toEqual({ externalSenderLabel: false, externalRecipientWarning: false, noThirdPartyTraffic: false });
+    expect(snapshotHostFeatures()).toEqual(withAssistant({ externalSenderLabel: false, externalRecipientWarning: false, noThirdPartyTraffic: false }));
     setExternalMail({ senderLabel: true });
-    expect(snapshotHostFeatures()).toEqual({ externalSenderLabel: true, externalRecipientWarning: false, noThirdPartyTraffic: false });
+    expect(snapshotHostFeatures()).toEqual(withAssistant({ externalSenderLabel: true, externalRecipientWarning: false, noThirdPartyTraffic: false }));
     setExternalMail({ recipientWarning: true });
-    expect(snapshotHostFeatures()).toEqual({ externalSenderLabel: false, externalRecipientWarning: true, noThirdPartyTraffic: false });
+    expect(snapshotHostFeatures()).toEqual(withAssistant({ externalSenderLabel: false, externalRecipientWarning: true, noThirdPartyTraffic: false }));
   });
 
   // A link check switches Google Safe Browsing off in the mode instead of
diff --git a/lib/plugin-sandbox/assistant/README.md b/lib/plugin-sandbox/assistant/README.md
new file mode 100644
index 000000000..cf0d413aa
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/README.md
@@ -0,0 +1,27 @@
+# Host APIs for the AI assistant (2.2)
+
+Host calls the assistant plugin needs, one set of files per area, so the
+areas can be built side by side without editing the same lines:
+
+| Area | What | Files |
+| --- | --- | --- |
+| b | More context: attachment text and images, threads, the list selection | `b.types.ts`, `b.ts`, `b.runtime.ts` |
+| c | More actions: invitations, filters, batches, out-of-office, settings | `c.types.ts`, `c.ts`, `c.runtime.ts` |
+| d | Files: find, read, attach, save, create | `d.types.ts`, `d.ts`, `d.runtime.ts` |
+| f | The panel in every view | `f.types.ts`, `f.ts`, `f.runtime.ts` |
+
+Each area fills its own three files:
+
+- `<area>.types.ts` (pure, no imports from the app): `PERMISSIONS`, the
+  permissions the area adds (they join `ALL_PERMISSIONS`), and
+  `<Area>HostFeatures`, the flags it adds to `api.host.features`.
+- `<area>.ts` (host side): `PERMS` (method → permission, joins
+  `PERM_PER_METHOD`), `dispatch(plugin, method, args)` (returns `NOT_MINE`
+  for methods it doesn't own) and `features()` (its flags right now).
+- `<area>.runtime.ts` (inside the sandbox): `runtime(callApi)`, the methods
+  it adds to the plugin's `api`, by namespace (`{ email: { getThread } }`).
+
+`index.ts`, `runtime.ts` and `types.ts` merge the areas; host-api.ts,
+host-features.ts, runtime.tsx and plugin-types.ts read only those. A new
+permission needs a check (a method in `PERMS`, a slot or a hook), its texts
+in every locale under `plugins.permissions.<key>`, and docs.
diff --git a/lib/plugin-sandbox/assistant/b.runtime.ts b/lib/plugin-sandbox/assistant/b.runtime.ts
new file mode 100644
index 000000000..b9e5f1850
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/b.runtime.ts
@@ -0,0 +1,8 @@
+// Area b of the assistant's host APIs, inside the plugin sandbox (see README.md).
+
+import type { CallApi, RuntimeAdditions } from './runtime';
+
+/** The methods this area adds to the plugin's api, by namespace. */
+export function runtime(_callApi: CallApi): RuntimeAdditions {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/b.ts b/lib/plugin-sandbox/assistant/b.ts
new file mode 100644
index 000000000..ea6ac7e71
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/b.ts
@@ -0,0 +1,18 @@
+// Area b of the assistant's host APIs, host side (see README.md).
+
+import type { InstalledPlugin, Permission } from '../../plugin-types';
+import { NOT_MINE } from './not-mine';
+import type { AreaHostFeaturesB } from './b.types';
+
+/** Method → permission, joined into PERM_PER_METHOD. */
+export const PERMS: Readonly<Record<string, Permission | null>> = {};
+
+/** Runs a method of this area; NOT_MINE for any other. */
+export async function dispatch(_plugin: InstalledPlugin, _method: string, _args: unknown[]): Promise<unknown> {
+  return NOT_MINE;
+}
+
+/** This area's flags in api.host.features, right now. */
+export function features(): AreaHostFeaturesB {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/b.types.ts b/lib/plugin-sandbox/assistant/b.types.ts
new file mode 100644
index 000000000..41e079eb8
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/b.types.ts
@@ -0,0 +1,9 @@
+// Area b of the assistant's host APIs: its permissions and its flags in
+// api.host.features (see README.md). Pure: no imports from the app.
+
+/** Permissions this area adds to ALL_PERMISSIONS. */
+export const PERMISSIONS = [] as const;
+
+/** Flags this area adds to api.host.features. */
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
+export interface AreaHostFeaturesB {}
diff --git a/lib/plugin-sandbox/assistant/c.runtime.ts b/lib/plugin-sandbox/assistant/c.runtime.ts
new file mode 100644
index 000000000..5e63b9136
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/c.runtime.ts
@@ -0,0 +1,8 @@
+// Area c of the assistant's host APIs, inside the plugin sandbox (see README.md).
+
+import type { CallApi, RuntimeAdditions } from './runtime';
+
+/** The methods this area adds to the plugin's api, by namespace. */
+export function runtime(_callApi: CallApi): RuntimeAdditions {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/c.ts b/lib/plugin-sandbox/assistant/c.ts
new file mode 100644
index 000000000..f0fc6c41e
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/c.ts
@@ -0,0 +1,18 @@
+// Area c of the assistant's host APIs, host side (see README.md).
+
+import type { InstalledPlugin, Permission } from '../../plugin-types';
+import { NOT_MINE } from './not-mine';
+import type { AreaHostFeaturesC } from './c.types';
+
+/** Method → permission, joined into PERM_PER_METHOD. */
+export const PERMS: Readonly<Record<string, Permission | null>> = {};
+
+/** Runs a method of this area; NOT_MINE for any other. */
+export async function dispatch(_plugin: InstalledPlugin, _method: string, _args: unknown[]): Promise<unknown> {
+  return NOT_MINE;
+}
+
+/** This area's flags in api.host.features, right now. */
+export function features(): AreaHostFeaturesC {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/c.types.ts b/lib/plugin-sandbox/assistant/c.types.ts
new file mode 100644
index 000000000..cebdb0f88
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/c.types.ts
@@ -0,0 +1,9 @@
+// Area c of the assistant's host APIs: its permissions and its flags in
+// api.host.features (see README.md). Pure: no imports from the app.
+
+/** Permissions this area adds to ALL_PERMISSIONS. */
+export const PERMISSIONS = [] as const;
+
+/** Flags this area adds to api.host.features. */
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
+export interface AreaHostFeaturesC {}
diff --git a/lib/plugin-sandbox/assistant/d.runtime.ts b/lib/plugin-sandbox/assistant/d.runtime.ts
new file mode 100644
index 000000000..0ce8066a4
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/d.runtime.ts
@@ -0,0 +1,8 @@
+// Area d of the assistant's host APIs, inside the plugin sandbox (see README.md).
+
+import type { CallApi, RuntimeAdditions } from './runtime';
+
+/** The methods this area adds to the plugin's api, by namespace. */
+export function runtime(_callApi: CallApi): RuntimeAdditions {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/d.ts b/lib/plugin-sandbox/assistant/d.ts
new file mode 100644
index 000000000..d6e69eba4
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/d.ts
@@ -0,0 +1,18 @@
+// Area d of the assistant's host APIs, host side (see README.md).
+
+import type { InstalledPlugin, Permission } from '../../plugin-types';
+import { NOT_MINE } from './not-mine';
+import type { AreaHostFeaturesD } from './d.types';
+
+/** Method → permission, joined into PERM_PER_METHOD. */
+export const PERMS: Readonly<Record<string, Permission | null>> = {};
+
+/** Runs a method of this area; NOT_MINE for any other. */
+export async function dispatch(_plugin: InstalledPlugin, _method: string, _args: unknown[]): Promise<unknown> {
+  return NOT_MINE;
+}
+
+/** This area's flags in api.host.features, right now. */
+export function features(): AreaHostFeaturesD {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/d.types.ts b/lib/plugin-sandbox/assistant/d.types.ts
new file mode 100644
index 000000000..2433c44fc
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/d.types.ts
@@ -0,0 +1,9 @@
+// Area d of the assistant's host APIs: its permissions and its flags in
+// api.host.features (see README.md). Pure: no imports from the app.
+
+/** Permissions this area adds to ALL_PERMISSIONS. */
+export const PERMISSIONS = [] as const;
+
+/** Flags this area adds to api.host.features. */
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
+export interface AreaHostFeaturesD {}
diff --git a/lib/plugin-sandbox/assistant/f.runtime.ts b/lib/plugin-sandbox/assistant/f.runtime.ts
new file mode 100644
index 000000000..f682649eb
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/f.runtime.ts
@@ -0,0 +1,8 @@
+// Area f of the assistant's host APIs, inside the plugin sandbox (see README.md).
+
+import type { CallApi, RuntimeAdditions } from './runtime';
+
+/** The methods this area adds to the plugin's api, by namespace. */
+export function runtime(_callApi: CallApi): RuntimeAdditions {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/f.ts b/lib/plugin-sandbox/assistant/f.ts
new file mode 100644
index 000000000..6565ac62b
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/f.ts
@@ -0,0 +1,18 @@
+// Area f of the assistant's host APIs, host side (see README.md).
+
+import type { InstalledPlugin, Permission } from '../../plugin-types';
+import { NOT_MINE } from './not-mine';
+import type { AreaHostFeaturesF } from './f.types';
+
+/** Method → permission, joined into PERM_PER_METHOD. */
+export const PERMS: Readonly<Record<string, Permission | null>> = {};
+
+/** Runs a method of this area; NOT_MINE for any other. */
+export async function dispatch(_plugin: InstalledPlugin, _method: string, _args: unknown[]): Promise<unknown> {
+  return NOT_MINE;
+}
+
+/** This area's flags in api.host.features, right now. */
+export function features(): AreaHostFeaturesF {
+  return {};
+}
diff --git a/lib/plugin-sandbox/assistant/f.types.ts b/lib/plugin-sandbox/assistant/f.types.ts
new file mode 100644
index 000000000..82361b441
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/f.types.ts
@@ -0,0 +1,9 @@
+// Area f of the assistant's host APIs: its permissions and its flags in
+// api.host.features (see README.md). Pure: no imports from the app.
+
+/** Permissions this area adds to ALL_PERMISSIONS. */
+export const PERMISSIONS = [] as const;
+
+/** Flags this area adds to api.host.features. */
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
+export interface AreaHostFeaturesF {}
diff --git a/lib/plugin-sandbox/assistant/index.ts b/lib/plugin-sandbox/assistant/index.ts
new file mode 100644
index 000000000..9d73e4a8d
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/index.ts
@@ -0,0 +1,29 @@
+// The assistant's host API areas, merged, host side (see README.md).
+
+import type { InstalledPlugin, Permission } from '../../plugin-types';
+import { NOT_MINE } from './not-mine';
+import * as b from './b';
+import * as c from './c';
+import * as d from './d';
+import * as f from './f';
+import type { AssistantHostFeatures } from './types';
+
+export { NOT_MINE };
+const AREAS = [b, c, d, f];
+
+/** Method → permission of every area, joined into PERM_PER_METHOD. */
+export const ASSISTANT_PERMS: Readonly<Record<string, Permission | null>> = Object.assign({}, ...AREAS.map((a) => a.PERMS));
+
+/** Runs an area's method; NOT_MINE when no area owns it. The permission is checked before. */
+export async function dispatchAssistant(plugin: InstalledPlugin, method: string, args: unknown[]): Promise<unknown> {
+  for (const area of AREAS) {
+    if (!(method in area.PERMS)) continue;
+    return area.dispatch(plugin, method, args);
+  }
+  return NOT_MINE;
+}
+
+/** Every area's api.host.features flags, right now. */
+export function assistantFeatures(): AssistantHostFeatures {
+  return Object.assign({}, ...AREAS.map((a) => a.features()));
+}
diff --git a/lib/plugin-sandbox/assistant/not-mine.ts b/lib/plugin-sandbox/assistant/not-mine.ts
new file mode 100644
index 000000000..3dd29ae6c
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/not-mine.ts
@@ -0,0 +1,2 @@
+/** What an area's dispatch returns for a method it doesn't own. */
+export const NOT_MINE: unique symbol = Symbol('not mine');
diff --git a/lib/plugin-sandbox/assistant/runtime.ts b/lib/plugin-sandbox/assistant/runtime.ts
new file mode 100644
index 000000000..8d0c42800
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/runtime.ts
@@ -0,0 +1,21 @@
+// The assistant's host API areas, merged, inside the plugin sandbox (see README.md).
+
+import { runtime as b } from './b.runtime';
+import { runtime as c } from './c.runtime';
+import { runtime as d } from './d.runtime';
+import { runtime as f } from './f.runtime';
+
+export type CallApi = (method: string, args: unknown[], timeoutMs?: number) => Promise<unknown>;
+/** Methods by namespace: { email: { getThread: (...) => ... } }. */
+export type RuntimeAdditions = Record<string, Record<string, (...args: never[]) => unknown>>;
+
+/** Adds every area's methods to the plugin's api, namespace by namespace. */
+export function withAssistantRuntime<T extends object>(api: T, callApi: CallApi): T {
+  const target = api as unknown as Record<string, Record<string, unknown>>;
+  for (const area of [b, c, d, f]) {
+    for (const [ns, methods] of Object.entries(area(callApi))) {
+      target[ns] = Object.assign(target[ns] ?? {}, methods);
+    }
+  }
+  return api;
+}
diff --git a/lib/plugin-sandbox/assistant/types.ts b/lib/plugin-sandbox/assistant/types.ts
new file mode 100644
index 000000000..a334c8131
--- /dev/null
+++ b/lib/plugin-sandbox/assistant/types.ts
@@ -0,0 +1,15 @@
+// The assistant's host API areas, merged: permissions and api.host.features
+// flags (see README.md). Pure: plugin-types.ts imports this.
+
+import { PERMISSIONS as B } from './b.types';
+import { PERMISSIONS as C } from './c.types';
+import { PERMISSIONS as D } from './d.types';
+import { PERMISSIONS as F } from './f.types';
+import type { AreaHostFeaturesB } from './b.types';
+import type { AreaHostFeaturesC } from './c.types';
+import type { AreaHostFeaturesD } from './d.types';
+import type { AreaHostFeaturesF } from './f.types';
+
+export const ASSISTANT_PERMISSIONS = [...B, ...C, ...D, ...F] as const;
+
+export interface AssistantHostFeatures extends AreaHostFeaturesB, AreaHostFeaturesC, AreaHostFeaturesD, AreaHostFeaturesF {}
diff --git a/lib/plugin-sandbox/host-api.ts b/lib/plugin-sandbox/host-api.ts
index 76e9a50e7..d12b847f9 100644
--- a/lib/plugin-sandbox/host-api.ts
+++ b/lib/plugin-sandbox/host-api.ts
@@ -74,6 +74,7 @@ import { doComposerAttach, doComposerGetBody, doComposerGetSelection, doComposer
 import { wkdAllowed } from '../outgoing-hosts';
 import { noThirdPartyTraffic } from '../third-party-mode';
 import { openExternalLink } from '../plugin-hook-result';
+import { ASSISTANT_PERMS, NOT_MINE, dispatchAssistant } from './assistant';
 
 /**
  * Methods only callable from the privileged (same-origin) tier. These expose
@@ -112,6 +113,8 @@ const PRIVILEGED_ONLY_METHODS = new Set<string>([
 ]);
 
 export const PERM_PER_METHOD: Readonly<Record<string, Permission | null>> = {
+  // The AI assistant's host APIs, one table per area (lib/plugin-sandbox/assistant).
+  ...ASSISTANT_PERMS,
   // storage is unscoped by the manifest - implicit.
   'storage.get': null,
   'storage.set': null,
@@ -2016,6 +2019,9 @@ export async function dispatchApiCall(
     throw new Error(`Unknown API method "${method}"`);
   }
 
+  const assistant = await dispatchAssistant(plugin, method, args);
+  if (assistant !== NOT_MINE) return assistant;
+
   switch (method) {
     case 'proxy.fetch': return proxyFetch(plugin, args, opts?.sink ?? null);
     case 'proxy.cancel': proxyCancel(plugin, args[0]); return undefined;
diff --git a/lib/plugin-sandbox/host-features.ts b/lib/plugin-sandbox/host-features.ts
index 63edc8cb3..0d82ac618 100644
--- a/lib/plugin-sandbox/host-features.ts
+++ b/lib/plugin-sandbox/host-features.ts
@@ -12,6 +12,7 @@ import { usePolicyStore } from '@/stores/policy-store';
 import { noThirdPartyTraffic, subscribeThirdPartyMode } from '@/lib/third-party-mode';
 import type { HostFeaturesView } from '../plugin-types';
 import type { OrganisationPolicy } from '@/lib/admin/organisation-policy';
+import { assistantFeatures } from './assistant';
 
 /** The external-mail-warning plugin, retired in favour of organisation.externalMail. */
 export const EXTERNAL_MAIL_WARNING_PLUGIN_ID = 'external-mail-warning';
@@ -26,7 +27,11 @@ export function hostFeaturesFor(externalMail: OrganisationPolicy['externalMail']
 }
 
 export function snapshotHostFeatures(): HostFeaturesView {
-  return hostFeaturesFor(usePolicyStore.getState().getOrganisation().externalMail, noThirdPartyTraffic());
+  return {
+    ...hostFeaturesFor(usePolicyStore.getState().getOrganisation().externalMail, noThirdPartyTraffic()),
+    // The AI assistant's host APIs this webmail offers (lib/plugin-sandbox/assistant).
+    ...assistantFeatures(),
+  };
 }
 
 /**
diff --git a/lib/plugin-sandbox/runtime.tsx b/lib/plugin-sandbox/runtime.tsx
index daf0ee0db..63b0b361a 100644
--- a/lib/plugin-sandbox/runtime.tsx
+++ b/lib/plugin-sandbox/runtime.tsx
@@ -38,6 +38,7 @@ import type {
   TaskView, TemplateInput, TemplateView, VacationInput, VacationView, ComposerSnapshot, ComposerAttachmentData,
 } from '../plugin-types';
 import { AddressBook, ContactCard } from '../jmap/types';
+import { withAssistantRuntime } from './assistant/runtime';
 import { EncryptionAtRestConfig, PublicKeyInput } from '@/stores/account-security-store';
 
 // ─── Module-scope state ──────────────────────────────────────
@@ -424,7 +425,12 @@ interface PluginKeywordCounts {
   unread: number;
 }
 
+/** The plugin's api, with the AI assistant's host APIs (lib/plugin-sandbox/assistant) added. */
 function buildPluginApi(manifest: PluginManifest) {
+  return withAssistantRuntime(buildCoreApi(manifest), callApi);
+}
+
+function buildCoreApi(manifest: PluginManifest) {
   applySettings({ ...manifest.settings });
   localeTables = JSON.parse(JSON.stringify(manifest.locales ?? {}));
   return {
diff --git a/lib/plugin-types.ts b/lib/plugin-types.ts
index fa1a74b5d..a122af6c6 100644
--- a/lib/plugin-types.ts
+++ b/lib/plugin-types.ts
@@ -1,5 +1,6 @@
 import type { CredentialSpec } from './plugin-secrets/credentials';
 import type { CatalogSlotName } from './plugin-slot-catalog';
+import { ASSISTANT_PERMISSIONS, type AssistantHostFeatures } from './plugin-sandbox/assistant/types';
 
 // Plugin & Theme system types
 
@@ -956,7 +957,7 @@ export interface AppInfoView {
  * that does the same job steps back while one is true. Missing on hosts
  * older than 1.19.0, so read it as `api.host?.features?.x === true`.
  */
-export interface HostFeaturesView {
+export interface HostFeaturesView extends AssistantHostFeatures {
   /** The admin turned on the "External" label on mail from outside the organisation (organisation.externalMail.senderLabel). */
   externalSenderLabel: boolean;
   /** The admin turned on the confirm before sending outside the organisation (organisation.externalMail.recipientWarning). */
@@ -1591,6 +1592,8 @@ export const ALL_PERMISSIONS = [
   'http:proxy',
   'admin:config',
   'app:lifecycle',
+  // The AI assistant's host APIs, one list per area (lib/plugin-sandbox/assistant).
+  ...ASSISTANT_PERMISSIONS,
 ] as const;
 
 export type Permission = (typeof ALL_PERMISSIONS)[number];