Potion Yjs Dev Browser Test
udecode/plate
A skill your agent uses when a Slate Yjs collaboration behavior is suspicious and Potion should be used as a live reference implementation through dev-browser, especially for offline/reconnect…
Apply Epicenter’s Yjs 14 patterns for row documents, transactions, persistence, and synchronization.
Custom licenceAuto-check passed
Install Yjs
$ npx skills add EpicenterHQ/epicenter --skill yjs -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install EpicenterHQ/epicenter yjs --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/yjs .claude/skills/yjs && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "yjs" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjs into .claude/skills/yjs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "yjs", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjsType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add EpicenterHQ/epicenter --skill yjs -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install EpicenterHQ/epicenter yjs --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/yjs .agents/skills/yjs && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "yjs" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjs into .agents/skills/yjs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "yjs", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add EpicenterHQ/epicenter --skill yjs -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install EpicenterHQ/epicenter yjs --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/yjs .cursor/skills/yjs && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "yjs" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjs into .cursor/skills/yjs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "yjs", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/EpicenterHQ/epicenter.git --path .agents/skills/yjs--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add EpicenterHQ/epicenter --skill yjs -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install EpicenterHQ/epicenter yjs --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/yjs .gemini/skills/yjs && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "yjs" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjs into .gemini/skills/yjs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "yjs", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install EpicenterHQ/epicenter yjsInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add EpicenterHQ/epicenter --skill yjs -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/yjs .github/skills/yjs && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "yjs" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjs into .github/skills/yjs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "yjs", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add EpicenterHQ/epicenter --skill yjs -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install EpicenterHQ/epicenter yjs --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/EpicenterHQ/epicenter.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/yjs .opencode/skills/yjs && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "yjs" agent skill from https://github.com/EpicenterHQ/epicenter/tree/main/.agents/skills/yjs into .opencode/skills/yjs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "yjs", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
yjs- GitHub stars
- 4.8k
- Token cost
- ~3.5k tokens
- SKILL.md length
- 1,815 words
- Files
- 3 (incl. references)
- Skills in repo
- 65
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
Apply Epicenter’s Yjs 14 patterns for row documents, transactions, persistence, and synchronization.
- Working with @y/y
- SKILL.md covers Reference Repositories, Upstream Grounding, Transactions, Origins, And Undo and Store Connection, plus 6 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Collaborative editing
What it does
Yjs is an agent skill from EpicenterHQ/epicenter. Apply Epicenter’s Yjs 14 patterns for row documents, transactions, persistence, and synchronization. Use when working with @y/y, CRDTs, collaborative editing, awareness, or Yjs storage and providers.
Its SKILL.md is about 3.5k tokens, which your agent loads only when the skill is triggered. The skill folder holds 3 other files, including reference files (for example `references/debugging.md` and `references/document-design.md`).
The repository describes itself as: Open-source, local-first apps.
When your agent uses it
- Working with @y/y
- Collaborative editing
- Yjs storage and providers
Example prompts
- “/yjs”
What it can do on your machine
Read from SKILL.md and the folder at commit 5b4bb69. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Links to these hosts (documentation or services it may open):
github.comlearn.yjs.devdocs.yjs.devresearchgate.net
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Yjs loads about 3.5k tokens when it runs, and up to ~5.1k if it reads all its reference files. Until then it costs about 51 tokens; SKILL.md has 1,815 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 1,815 words (~3,503 tokens).
“When conflict semantics, transaction origins, shared-type behavior, update encoding, storage growth, or shared-type APIs affect correctness, use source-backed grounding before relying on memory. If DeepWiki MCP is available, ask a narrow question against yjs/yjs; for sync and awareness algorithms, ask…”
- name
- yjs
- metadata.author
- epicenter
- metadata.version
- 1.0
Files
SKILL.md and 2 other files (references) in .agents/skills/yjs of EpicenterHQ/epicenter.
- SKILL.md
- references/debugging.md
- references/document-design.md
Open the folder on GitHubat commit 5b4bb69
Compare with similar skills
Yjs next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Yjs this skillEpicenterHQ/epicenter | 4.8k | — | ~3.5k | Automated safety check: Pass | Custom licence | |
| Potion Yjs Dev Browser Testudecode/plate | 17k | — | ~1.1k | Automated safety check: Pass | Custom licence | |
| Flutter Use Column Row Firstevanca/flutter-ai-rules | 650 | — | ~1.3k | Automated safety check: Pass | MIT | |
| Websocket Yjsexelearning/exelearning | 147 | — | ~759 | Automated safety check: Pass | AGPL-3.0 | |
| Handsontable Coordinate Systemshandsontable/handsontable | 22k | — | ~721 | Automated safety check: Pass | Custom licence | |
| Excel Subtotal AuditHKUDS/OpenSpace | 7.8k | — | ~3.5k | Automated safety check: Pass | MIT |
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Websocket Yjs
exelearning/exelearning
Change eXeLearning shared document mutations, WebSocket rooms, snapshots, reconnects or concurrent editing behavior.
Handsontable Coordinate Systems
handsontable/handsontable
Explains Handsontable's physical, visual and renderable row and column coordinate spaces and how to convert between them with IndexMapper, for debugging misplaced rows or columns.
Excel Subtotal Audit
HKUDS/OpenSpace
Audit generated Excel reports by enumerating populated output rows, exposing formulas, and checking that each subtotal range includes all visible detail rows.
Paired Reversal Cancellation
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Reference for paired-reversal handling on GL batch tapes: an RV row whose ref-trace points at an earlier row cancels BOTH legs (the RV and the row it references) — but ONLY when the two value-dates…
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Questions about Yjs
What does Yjs do?
Apply Epicenter’s Yjs 14 patterns for row documents, transactions, persistence, and synchronization. Yjs is an agent skill from EpicenterHQ/epicenter. Apply Epicenter’s Yjs 14 patterns for row documents, transactions, persistence, and synchronization.
When should I use Yjs?
Yjs fits situations like: working with @y/y; collaborative editing; yjs storage and providers.
How do I install Yjs in Claude Code?
Run `npx skills add EpicenterHQ/epicenter --skill yjs -a claude-code`. Or copy the skill folder (.agents/skills/yjs in EpicenterHQ/epicenter) into .claude/skills/yjs in your project. Claude Code loads it when a task matches its description.
How do I install Yjs in Codex?
Run `npx skills add EpicenterHQ/epicenter --skill yjs -a codex`. Or copy the skill folder (.agents/skills/yjs in EpicenterHQ/epicenter) into .agents/skills/yjs in your project. Codex loads it when a task matches its description.
Can I use Yjs in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add EpicenterHQ/epicenter --skill yjs -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/yjs, .gemini/skills/yjs, .github/skills/yjs and .opencode/skills/yjs in your project.
What does Yjs need to run?
SKILL.md names no scripts, command-line tools or credentials: Yjs is instructions for the agent only.
Does Yjs access the network?
SKILL.md names 4 domains. As links in the text: github.com, learn.yjs.dev, docs.yjs.dev and researchgate.net. This is read from the text; nothing was executed.
Is Yjs safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Yjs use?
Yjs has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
How many tokens does Yjs use?
About 3.5k tokens (SKILL.md is roughly 14k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.6k tokens, read only when the agent opens those files.
What are the alternatives to Yjs?
Skills that share tags, products or a category with Yjs: Potion Yjs Dev Browser Test (udecode/plate, 17k stars), Flutter Use Column Row First (evanca/flutter-ai-rules, 650 stars), Websocket Yjs (exelearning/exelearning, 147 stars) and Handsontable Coordinate Systems (handsontable/handsontable, 22k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Yjs?
EpicenterHQ (a GitHub organization) maintains it in EpicenterHQ/epicenter, which has 4,821 GitHub stars. The repository holds 65 skills in this directory. The repository was last updated on October 8, 2026.
Source: EpicenterHQ/epicenter on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.