Recover editor runtime after renderer full page reload

[kostyafarber]

Problem

The current HMR runtime work preserves editor state during React Fast Refresh, but Vite can still issue a full page reload for non-component dependency changes such as src/lib/keyboard/types.ts.

A full page reload destroys the renderer JavaScript realm. globalThis singletons, React providers, and renderer-local editor state cannot survive that boundary.

Distinction

Fast Refresh fixes and full reload recovery are different problems:

• Fast Refresh: preserve one renderer JS realm; split provider/context exports; keep React as a view shell.
• Full page reload: recreate the renderer page and reconnect to durable state owned elsewhere, or reconstruct session state from a saved snapshot.

Direction

Treat full reload as a renderer recovery path:

• Avoid avoidable reloads by keeping provider modules Fast Refresh-safe and local @shift/* packages out of stale Vite prebundles.
• Reconnect the renderer to the existing utility workspace session after reload.
• Reconstruct at least the route glyph scene so the canvas does not blank.
• Later, consider session-scoped records for scene nodes, selection, editing state, and tool state.

Acceptance criteria

• Editing a dependency that causes Vite page reload reconnects to the existing workspace session.
• The editor route reconstructs the current glyph scene after reload.
• Canvas surfaces reattach without requiring a full app restart.
• The HMR ticket clearly distinguishes Fast Refresh from full reload recovery.

Obsidian context: hmr-editor-runtime-ticket.md.