Codex and the MCP

Figmaboy starts codex app-server when you open its Codex sidebar. App-server launches the bundled figmaboy-mcp process over stdio using a process-local configuration override, so the integrated chat does not modify your global Codex configuration. Figmaboy uses ephemeral Codex runtime threads and stores the visible conversations itself. These chats appear only inside Figmaboy.

Two data paths

Figmaboy sidebar
  │ app-server protocol over stdio
  ▼
Codex app-server
  │ MCP over stdio
  ▼
figmaboy-mcp
  ├── read-only SQLite ───────────► saved pages, layers, previews
  │                                  app open or closed
  │
  └── authenticated loopback ─────► currently open editor
                                     live inspect and edit

Saved context

designs_list and design_context_get open the local SQLite workspace in read-only mode. They can find a design by copied file ID or unique name and return:

• File and page identity.
• The saved revision.
• The complete native page document.
• An ordered layer tree.
• Asset metadata.
• A visual page preview when available.

The MCP never writes to SQLite. Offline context works while the desktop application is closed.

Live editor tools

When Figmaboy is open, it starts a loopback-only bridge on a random port. A discovery file contains that port, a random authentication token, and the desktop process ID. Live MCP tools connect to that bridge.

The editor applies each mutation. It uses the same validation, history, rendering, revision checks, and autosave path as a manual edit.

Optimistic concurrency

editor_status and document_get return a change token. Codex can pass it as expectedChangeToken when applying edits. If the document changed after inspection, Figmaboy rejects the stale edit instead of silently overwriting newer work.

Tool discovery

The integrated sidebar tells each new thread which Figmaboy file is open. It supplies the bundled MCP without changing global Codex configuration. Only external Codex clients need a separate MCP installation.

The model picker comes from app-server’s paginated model/list catalog. Figmaboy validates reasoning and service-tier choices against the selected model, then uses the effective values returned by thread/start. When you reopen a saved Figmaboy chat, the app creates a fresh ephemeral runtime thread and restores the recent user and assistant conversation before continuing.

At the start of a design task, Codex should inspect:

1. editor_status to confirm the active file and page.
2. design_capabilities for supported nodes, styles, and hierarchy rules.
3. types_get when it needs the exact TypeScript contract.
4. document_get for the complete current document and change token.

After editing, it should use frame_screenshot for visual review and document_save to persist the finished revision.