yjs-nextjs

name

yjs-nextjs

description

Corrects the wrong defaults a capable model has when building Yjs collaborative editing into a Next.js 16 App Router app with tRPC v11 and shadcn/ui — pinned to Yjs 13.6.31. Covers the decisions whose failure mode is silence rather than an error — plain objects in a Y.Map discarding concurrent edits, updates that vanish because a JSON boundary turned a Uint8Array into a number array, undo that reverts a colleague's paragraph, initial content seeded once per client, and carets thrown to the end of a shadcn Input on every remote keystroke. Also covers where the sync loop can actually run, since route handlers cannot upgrade, Vercel Functions have no instance affinity, and tRPC subscriptions are one-way — plus which packages have already moved to the Yjs 14 prerelease track. Use when writing, reviewing, or debugging collaborative editing, presence, offline sync, or CRDT persistence in this stack.

Yjs in Next.js 16, tRPC, and shadcn/ui

Yjs 13.6.31 in an App Router codebase — the decisions collaborative editing forces and how to settle them, written so an agent applies them while writing or reviewing code. Each rule names the wrong default it corrects; there is no rule for things the model already gets right.

Most of these failures are silent. Yjs converges, the editor keeps working, and the data loss surfaces later as "my change reverted" — so the rules below lead with the evidence of the failure, most of it measured directly against Yjs 13.6.31 rather than asserted.

When to Apply

• Building collaborative editing, presence, or offline sync into a Next.js 16 App Router app
• Choosing shared types for a document model, or reviewing one that loses edits under concurrency
• Deciding where the sync backend runs, or wiring tRPC procedures alongside a Yjs provider
• Persisting Y.Doc state to a database, or compacting stored updates
• Binding a Yjs document to React — provider lifecycle, subscriptions, Strict Mode, SSR
• Wiring Tiptap or shadcn/ui form controls to a live document
• Debugging a document that syncs but duplicates, blanks, or reverts content