A personal Android messaging app that connects to the Saturday container, enabling voice interaction with Saturday while driving via Android Auto.

Problem

Discord doesn't support sending messages on Android Auto. Paul commutes to Toronto 1-2 days per week and can't interact with Saturday while driving. Voice interaction would be the most natural and safe interface for in-car use.

Core Concept

• A lightweight Android app categorized as a messaging app
• Connects to the Saturday container via WebSocket through the existing Cloudflared Tunnel
• Incoming Saturday messages surface as MessagingStyle notifications, which Android Auto reads aloud
• Paul replies via Android Auto's built-in speech-to-text, which routes through RemoteInput back to the app, then to Saturday via the MCP channel
• Sideloaded as a developer app - no Play Store review needed for personal use

Architecture

flowchart LR
    A["Android Auto"] -->|Voice reply / STT| B["Saturday App"]
    B -->|WebSocket| C["Cloudflare Tunnel"]
    C -->|MCP Channel| D["Saturday Container"]
    D -->|Response| C
    C -->|WebSocket| B
    B -->|MessagingStyle Notification| A

App Components

• MessagingService - handles incoming messages from Saturday, surfaces as notifications
• RemoteInput handler - captures voice replies from Android Auto's STT
• WebSocket client - persistent connection to Friday container via Cloudflare Tunnel
• Notification manager - handles read state, conversation grouping, message history

Server Side (Saturday Container)

• MCP channel server (same pattern as the HA channel)
• Receives messages from the Android app