Runtime Boundaries

Placeholder — This document will contain the full runtime boundary reference. For now, see the runtime boundary sections in architecture-reference.md.

Overview

AF operates across three independent runtimes with strict responsibility boundaries. No runtime may assume another's responsibilities.

┌─────────────────┐   HTTP/WS   ┌─────────────────┐   WebSocket   ┌─────────────────┐
│     Watcher      │ ──────────▶ │     Server       │ ────────────▶ │  Figma Plugin    │
│  (Reconciliation │ ◀────────── │  (Relay + Audit) │ ◀──────────── │  (Mutation Only) │
│   + Analysis)    │             │                  │               │                  │
└─────────────────┘             └─────────────────┘               └─────────────────┘

Runtimes

Runtime	Responsibility	Cannot do
Watcher (Node.js)	Reconciliation, AST analysis, adapter reads, token resolution	Write to Figma directly
Server (Node.js)	Message relay, audit logging, override persistence	Interpret UI meaning
Plugin (Figma sandbox)	Execute Figma mutations, report selections	Access filesystem, make network calls (in code.ts)

Boundary Constraints

• Figma code.ts has no network and no filesystem access — this is enforced by the Figma sandbox
• Figma ui.html can make network requests but must not assume localhost is reachable — always support configurable SERVER_URL and polling fallback
• The watcher is the only runtime that runs adapters and resolves fields
• The server never interprets message content — it relays and logs

Detailed Reference

The full runtime boundary specification, including protocol definitions, message formats, and cross-process communication rules, is documented in architecture-reference.md.