feat(plugin): document-root relaunch button for one-click reopen

[jamesjohn-ui]

Problem

Multi-file Figma workflows — especially when paired with AI agents driving the Bridge — need a reliable way to reopen the Bridge per file. Today, every reopen requires:

Plugins > Development > Figma Desktop Bridge > Run

That's three clicks of menu friction every time you switch back to a file where the Bridge was previously running. For agents that need the Bridge alive in the active file to do anything useful, this turns into a constant interrupt.

Solution

Plant a per-file relaunch button on figma.root via setRelaunchData, plus a matching relaunchButtons entry in the plugin manifest. Once the Bridge has run in a file, the design panel surfaces a one-click "Open Figma Desktop Bridge" button when nothing is selected.

The relaunch data is persisted with the document — survives close/reopen, Figma restarts, and syncs across collaborators on the same file.

Scope (honest)

This only helps re-opens in files where the Bridge has already run at least once. The first launch per file is still user-driven.

That gap is structural: Figma's plugin API does not expose any cross-file launch surface (no relaunchButtons/setRelaunchData usage exists prior to this PR, no Widget surface in this plugin, no cross-file events). I'm deliberately not trying to paper over that limitation.

A broader UI overhaul (settings modal, port override, debug copy, etc.) is out of scope here — happy to follow up with a separate PR if that's of interest.

Testing

Verified end-to-end in a scratch Figma file:

• setRelaunchData call succeeds on document root (no thrown error path hit)
• Relaunch button renders in the design panel when no node is selected
• Button persists across close/reopen of the file
• Button persists across full Figma app restart
• Click-to-launch fires the plugin with figma.command === 'open'

Files changed

• figma-desktop-bridge/code.js — +13 lines (try/catch around figma.root.setRelaunchData inside the existing loadAllPagesAsync().then(...) block)
• figma-desktop-bridge/manifest.json — +3 lines (top-level relaunchButtons array with one { command: "open", name: "Open Figma Desktop Bridge" } entry)

No behavioural changes outside the relaunch surface. The try/catch guards against any edge case (e.g. permissions, future API changes) without affecting the rest of the bootstrap.