diff --git a/lib/__tests__/plugin-assistant-c-features.test.ts b/lib/__tests__/plugin-assistant-c-features.test.ts
new file mode 100644
index 000000000..61d637de6
--- /dev/null
+++ b/lib/__tests__/plugin-assistant-c-features.test.ts
@@ -0,0 +1,32 @@
+import { describe, expect, it, vi } from 'vitest';
+import type { InstalledPlugin } from '../plugin-types';
+
+vi.mock('@/stores/toast-store', () => ({
+  toast: { success: vi.fn(), error: vi.fn(), info: vi.fn(), warning: vi.fn() },
+}));
+
+const { snapshotHostFeatures } = await import('../plugin-sandbox/host-features');
+
+// A plugin sees answerInvitation and changeSettings only once it was granted
+// the optional permission behind them: one enabled before the update that
+// added them doesn't have it until the user turns it off and on.
+
+function plugin(granted: string[]): InstalledPlugin {
+  return {
+    id: 'ai-assistant', name: 'AI', version: '2.2.0', author: 'test', description: '', type: 'hook',
+    permissions: ['calendar:respond', 'settings:change'], grantedPermissions: granted,
+    entrypoint: 'index.js', enabled: true, status: 'running', settings: {},
+  } as InstalledPlugin;
+}
+
+describe('the area c flags for one plugin', () => {
+  it('follow what the plugin was granted', () => {
+    expect(snapshotHostFeatures(plugin([]))).toMatchObject({ answerInvitation: false, changeSettings: false, batchMail: true });
+    expect(snapshotHostFeatures(plugin(['calendar:respond']))).toMatchObject({ answerInvitation: true, changeSettings: false });
+    expect(snapshotHostFeatures(plugin(['calendar:respond', 'settings:change']))).toMatchObject({ answerInvitation: true, changeSettings: true });
+  });
+
+  it('say what the webmail offers when no plugin is named', () => {
+    expect(snapshotHostFeatures()).toMatchObject({ answerInvitation: true, changeSettings: true });
+  });
+});
diff --git a/lib/plugin-sandbox/assistant/c.ts b/lib/plugin-sandbox/assistant/c.ts
index e4b4b6e65..410222978 100644
--- a/lib/plugin-sandbox/assistant/c.ts
+++ b/lib/plugin-sandbox/assistant/c.ts
@@ -14,6 +14,7 @@ import { useVacationStore } from '@/stores/vacation-store';
 import { doVacationGet, doVacationSet } from '../host-api-settings';
 import { isPlainRecord, sessionClient } from '../host-api-input';
 import { NOT_MINE } from './not-mine';
+import { pluginHasPermission } from '../permissions';
 import { doCalendarDeleteWithUndo, doCalendarRespond, doCalendarUndoDelete } from './c.calendar';
 import { doFiltersCreate, doFiltersList, doFiltersUndo } from './c.filters';
 import { doEmailBatch, doEmailUndoBatch } from './c.batch';
@@ -94,13 +95,18 @@ export async function dispatch(plugin: InstalledPlugin, method: string, args: un
   }
 }
 
-/** This area's flags in api.host.features, right now. */
-export function features(): AreaHostFeaturesC {
+/**
+ * This area's flags in api.host.features, right now. For one plugin, the
+ * calls behind a new optional permission count only once it was granted (a
+ * plugin enabled before an update lacks them until turned off and on).
+ */
+export function features(plugin?: InstalledPlugin): AreaHostFeaturesC {
   const client = useAuthStore.getState().client;
+  const granted = (permission: Permission) => !plugin || pluginHasPermission(plugin, permission);
   return {
-    answerInvitation: true,
+    answerInvitation: granted('calendar:respond'),
     filterRules: client?.supportsSieve?.() === true,
     batchMail: true,
-    changeSettings: true,
+    changeSettings: granted('settings:change'),
   };
 }