Optional features

Every optional feature can be switched off, in two layers (packages/shared/src/features.ts):

• Instance (env FEATURE_*, see .env.example): what this deployment offers. At startup the API logs each feature as on, or off with the reason.
• User (Settings → Features, stored in users.settings.features): each user can switch features off for themselves. They can't switch on anything the instance doesn't offer.

Dependencies apply automatically: prep, chat and follow-up drafts need AI, and portal sync needs the extension. AI also needs an API key the user may use (BYOK). Everything goes through one helper, featureState/isEnabled:

• the API answers 403 feature_disabled with the reason;
• background jobs skip;
• the web app and extension hide the surface.

API tokens exist only for the extension. With the extension off, token requests are refused, except self-revoke, so Disconnect still works.