yjs-best-practices

name: yjs-best-practices description: "Yjs CRDT best practices for building real-time collaborative applications. Use this skill when implementing collaborative editing, real-time sync, shared data structures, or any feature using Yjs (Y.Doc, Y.Text, Y.Array, Y.Map, Y.XmlFragment). Triggers on tasks involving Yjs, CRDTs, collaborative editors, y-websocket, y-webrtc, y-indexeddb, y-prosemirror, y-codemirror, y-quill, y-monaco, awareness/presence, undo/redo with shared types, or any mention of real-time document collaboration — even if the user doesn't explicitly say 'Yjs'." license: MIT metadata: author: velt version: "1.1.0"

Yjs Best Practices

Comprehensive guide for implementing real-time collaborative applications with Yjs — the high-performance CRDT framework. Contains 24 rules across 8 categories covering document lifecycle, shared types, providers, editor bindings, awareness, undo/redo, common pitfalls, and debugging.

When to Apply

Reference these guidelines when:

• Creating or managing Y.Doc instances for collaborative documents
• Using shared types (Y.Text, Y.Array, Y.Map, Y.XmlFragment) for synced data
• Setting up network providers (y-websocket, y-webrtc) or persistence (y-indexeddb)
• Integrating Yjs with editors (TipTap, ProseMirror, CodeMirror, Quill, Monaco)
• Implementing user presence and cursor awareness
• Adding undo/redo to collaborative editing
• Debugging sync issues, state vector mismatches, or update encoding

Rule Categories by Priority

Quick Reference

Core (CRITICAL)

• core-ydoc-setup — Y.Doc creation, clientID, gc setting
• core-transactions — transact() bundling, origin parameter, event ordering
• core-document-updates — encodeStateAsUpdate, applyUpdate, mergeUpdates, state vectors
• core-garbage-collection — gc flag, when to disable for version history

Shared Types (CRITICAL)

• types-ytext — Text & RichText, insert/format/delta, Quill compatibility
• types-yarray — Ordered sequences, insert/delete/push, nested types
• types-ymap — Key-value storage, observe, historical key retention gotcha
• types-ymap-ykeyvalue — YKeyValue from y-utility for efficient key-value (524KB → 271B)
• types-xml — Y.XmlFragment/Element/Text for structured documents

Providers (HIGH)

• provider-websocket — y-websocket client and server setup
• provider-webrtc — y-webrtc peer-to-peer connections
• provider-indexeddb — y-indexeddb offline persistence
• provider-custom — Building custom providers, update properties

Editor Bindings (HIGH)

• binding-tiptap — y-prosemirror with TipTap
• binding-prosemirror — y-prosemirror directly
• binding-codemirror — y-codemirror.next
• binding-quill — y-quill
• binding-monaco — y-monaco

Awareness (MEDIUM-HIGH)

• awareness-protocol — Presence, cursors, setLocalStateField

Undo/Redo (MEDIUM)

• undo-manager — Y.UndoManager, captureTimeout, trackedOrigins, cursor restoration

Pitfalls & Debugging (MEDIUM)

• pitfall-duplicate-imports — CJS/ESM double-import breaks sync
• pitfall-subdocuments — When to use vs Y.Map alternatives
• pitfall-v2-encoding — useV2Encoding experimental flag
• debug-common-issues — logUpdate, state inspection, connection debugging

How to Use

Read individual rule files for detailed explanations and code examples:

rules/core/core-ydoc-setup.md
rules/shared-types/types-ytext.md
rules/providers/provider-websocket.md

Each rule file contains:

• Brief explanation of why it matters
• Correct code example with explanation
• Verification checklist
• Source pointers to official docs

Compiled Documents

• AGENTS.md — Compressed index of all rules with file paths (start here)
• AGENTS.full.md — Full verbose guide with all rules expanded inline