webmail/lib/plugin-sandbox/assistant

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.