docs: user profiles rfc (#1656)

docs/rfcs/2022-12-17-user-profiles.md

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+# User profiles
+
+## Problem
+
+Convenience of having different communication contexts in a single client without shared metadata.
+
+Currently requires changing chat database and restarting chat.
+
+Events (notifications) for databases other than current are not received.
+
+## Solution
+
+Support for multiple user profiles in a single database.
+
+Separate transport connections with the same servers not shared between profiles.
+
+## Design
+
+### API
+
+- new users are created using existing CreateActiveUser API
+
+- APIListUsers
+
+- APISetActiveUser UserId
+
+- CRUsersList {users :: [User]}
+
+- terminal APIs
+
+### Subscriptions
+
+- get connections for all users, subscribe to all - to receive events for users other than active
+
+- map subscriptions to users?
+
+- option to subscribe to connections for only one user? `StartChat {allUsers :: Bool}` API
+
+- if more than one user profiles - start with last active user (persist?), or always load list of users first and wait for choice? same for terminal?
+
+### Chat items expiration
+
+- store supports this configuration per user
+
+- expire chat items for all users with different ttl
+
+  - in `runExpireCIs` get list of users, for each - `getChatItemTTL` and run `expireChatItems`
+
+### Disappearing messages
+
+- `cleanupManager` - remove parameterization by User
+
+- either `getTimedItems` and start deletion threads for all users, or similar to expiration get list of users and run `cleanupTimedItems` per user
+
+### Events
+
+- events need to have information for which user they happened
+
+  ```haskell
+  data UserChatResponse = UserChatResponse
+    { user :: User,
+      chatResponse :: ChatResponse
+    }
+  ```
+
+- replace ChatResponse with UserChatResponse in APIResponse, toView, etc.
+
+- in `agentSubscriber` don't get currentUser from controller, instead either:
+
+  - get user from database by agent connection id
+
+  - get from subscriptions user-connections map - either requires scan or keys and values have to be inverted, also key would have to be agent connection id not database connection id - probably easier/better to read from db
+
+- non active user profile can be shown in notifications
+
+- interactions via notifications - prohibit for simplicity? or change APIs to allow specifying User?
+
+- changes to chat model are applied only for current user
+
+### ChatController
+
+- currentCalls:
+
+  - change `currentCalls` key? `currentCalls :: TMap (UserId, ContactId) Call`
+
+  - `restoreCalls` - for all users?
+
+  - interaction via notification - prohibit for non active user? change current user before accepting?
+
+- `incognitoMode` - save setting or share between users?
+
+- when changing active user reset `activeTo`?
+
+- in `newChatController` when creating smpAgent - `getSMPServers` have to get servers for all users, or depending on allUsers flag in StartChat; // drop known_servers table?
+
+- `AgentConfig` should depend on network configuration per user?
+
+- double check other state
+
+### Storage
+
+- schema already has support for multiple users
+
+- persist last active user?
+
+- persist user settings? (see below)
+
+### Frontend
+
+- view with list of user profiles available from settings, change active user from there
+
+- do we need additional information in that view? for example, number of unread messages
+
+- network configuration is stored in app preferences - if unchanged will be the same across users
+
+  - persist in database per user and load?
+
+  - different configuration across platforms
+
+  - save network settings in separate preference for each user as json? dynamic preferences or predefined number of users?
+
+- same for other settings - auto-accept images, send link previews, etc.
+
+### Terminal view
+
+- for users other than active view responses to have indication that it's for a different user profile, e.g. `[<user_name>]`, `[user: <user_name>]`
+
+- don't set `activeTo` for non active user profiles
+
+- only way to reply to a message in other user profile is to manually switch current active user first?