Architecture

                     ┌──────────┐
          login      │  Auth0   │
     ┌──────────────▶│  (JWT)   │
     │               └──────────┘
┌────┴─────┐  REST/protobuf   ┌──────────────┐      ┌────────────┐
│  Client  │─────────────────▶│ Lupyd Server │─────▶│ PostgreSQL │
│   app    │                  └──────┬───────┘      └────────────┘
│          │                         │ admin API (push, blocks, accepts)
│          │  REST/protobuf   ┌──────▼───────┐      ┌────────────┐
│          │─────────────────▶│   Firefly    │─────▶│ PostgreSQL │
│          │◀────────────────▶│    server    │      └────────────┘
└──────────┘  WebSocket /     └──┬────────┬──┘
              WebTransport       │        │
                          ┌──────▼──┐  ┌──▼──────────────┐
                          │   FCM   │  │ Encrypted blobs │
                          │ (push)  │  │      (CDN)      │
                          └─────────┘  └─────────────────┘

Components

Component	Role
Client apps	Android, iOS, desktop, and web apps. Messaging cryptography runs on the device through the Firefly client SDK.
Auth0	Identity provider. Issues RS256 access tokens carrying uname and perms claims.
Lupyd Server	Social graph and content. Stateless HTTP; PostgreSQL storage.
Firefly server	Delivery service and directory for encrypted messaging. Stores ciphertext, key packages, and prekey bundles; validates MLS commits; pushes messages in real time.
CDN	Stores encrypted attachments, group history chunks, and backups.

Request flow

1. The client signs the user in with Auth0 and receives an access token.
2. Social actions (profile, posts, follows) go to the Lupyd Server.
3. The client registers the device with Firefly, obtains a signed device credential, uploads key material, and opens a real-time connection.
4. Messages are encrypted on the device and sent through Firefly, which relays them to the recipients’ devices — or stores them until those devices reconnect — and sends a push notification.
5. When a user blocks or accepts someone on the Lupyd Server, the server mirrors the change to Firefly so messaging and calls respect it.

Trust model

• The servers never see plaintext messages or message keys.
• Group handshake messages (commits) are visible to Firefly so it can enforce group rules and permissions; application messages are always encrypted.
• Device credentials are signed by Firefly and bound to the user’s Auth0 identity, so members can verify who owns each device in a group.

See End-to-end encryption for details.