Architecture¶

Radix Relay implements a layered architecture for hybrid mesh communications.

Processor and Queue Architecture¶

The system uses async message queues to connect processors. Each processor owns exactly one input queue and can send messages to any other processor's queue.

flowchart TB
    USER(["User"])
    UI["gui/tui"]
    DISP["display_filter"]
    CMD["event_handler"]
    PRES["presentation_handler"]
    CONN["connection_monitor"]
    ORCH["session_orchestrator"]
    TRANS["nostr::transport"]
    WS["websocket_stream"]
    RELAY(["Nostr Relay"])

    USER <--> UI
    DISP -->|ui_event_queue| UI
    UI -->|event_handler_queue| CMD
    CMD -->|display_filter_queue| DISP
    CMD -->|connection_monitor_queue| CONN
    CMD -->|session_queue| ORCH
    CMD -->|transport_queue| TRANS
    CONN -->|display_filter_queue| DISP
    PRES -->|display_filter_queue| DISP
    ORCH -->|presentation_queue| PRES
    ORCH -->|connection_monitor_queue| CONN
    ORCH -->|transport_queue| TRANS
    TRANS -->|session_queue| ORCH
    TRANS <--> WS <--> RELAY

Key Components¶

User Interface Layer¶

Graphical UI (GUI) - Modern graphical interface built with Slint framework:

Cross-platform support (Windows, macOS, Linux)
Message scrolling with auto-scroll
Bundled fonts for consistent appearance

Terminal UI (TUI) - Command-line interface for headless environments and SSH sessions.

Both interfaces share the same backend event system and provide identical functionality.

Signal Protocol ¶

End-to-end encryption with forward and future secrecy using X3DH key agreement and Double Ratchet algorithm.

Transport Layer ¶

Unified interface for multiple transport mechanisms (Nostr, BLE, and future protocols).

Hybrid Routing ¶

Intelligent routing that prefers internet connectivity but seamlessly falls back to mesh networking.

Design Principles¶

Security First - All messages encrypted end-to-end
Resilient - Works with partial infrastructure
Modular - Clean separation between layers
Extensible - Easy to add new transports