ModelRouter now supports multiple tier-change listeners via addOnTierChange(),
SessionBridge subscribes to tier changes and propagates them to all WebChat
agents (both existing and newly created), and the fullscreen TUI now also
updates the agent's tier when switching models (matching minimal TUI behavior).
Phase 2 of the Flynn roadmap. Adds a WebSocket gateway server that
starts alongside the Telegram bot, providing real-time API access to
the agent, sessions, and tools.
Protocol: JSON-RPC-like (request/response/event) over WebSocket.
8 methods: agent.send, agent.cancel, sessions.list, sessions.history,
sessions.create, tools.list, tools.invoke, system.health.
Auth: Bearer token + Tailscale identity header support.
Session bridge: per-connection agent instances with shared model router.
New files: src/gateway/ (protocol, router, server, auth, session-bridge,
handlers for agent/sessions/tools/system).
57 new tests (181 total), typecheck clean.