P3.1 · Vault file watcher + debounced push to Linear

Pro-tier feature

What

Subscribe to vault.on('modify', file). When a synced note (has linear_id in frontmatter) changes:

1. Debounce 2s to coalesce rapid keystroke edits.
2. Diff current body against cached last_known_remote_body for that note.
3. If changed, call issueUpdate(id, { description: markdown }) via the Linear client.
4. On success, update synced_at and last_known_remote_body in the sync cache.

Technical requirements

• Don't push if only frontmatter changed (those are system-managed fields).
• If the push fails due to rate limit, the client backoff takes over; user sees a discreet Notice only on hard failure.
• Gate this feature behind license check — Free users get a "Pro required" Notice if they try to edit a synced note.

Acceptance criteria

• Editing a synced note and waiting 3s pushes the update to Linear.
• Editing frontmatter-only does NOT trigger a push.
• Rapid edits within 2s are coalesced to one push.