Agent skill

Assistant UI Runtime

Guide for assistant-ui runtime system and state management. An agent skill from compozy/compozy.

Install Assistant UI Runtime

skills CLI

$ npx skills add compozy/compozy --skill assistant-ui-runtime -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install compozy/compozy assistant-ui-runtime --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/compozy/compozy.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/assistant-ui/assistant-ui-runtime .claude/skills/assistant-ui-runtime && rm -rf skills-src

Use ~/.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/

Paste into Claude Code

Install the "assistant-ui-runtime" agent skill from https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime into .claude/skills/assistant-ui-runtime/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "assistant-ui-runtime", 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

$skill-installer install https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime

Type 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.

skills CLI

$ npx skills add compozy/compozy --skill assistant-ui-runtime -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install compozy/compozy assistant-ui-runtime --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/compozy/compozy.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/assistant-ui/assistant-ui-runtime .agents/skills/assistant-ui-runtime && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "assistant-ui-runtime" agent skill from https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime into .agents/skills/assistant-ui-runtime/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "assistant-ui-runtime", 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.

skills CLI

$ npx skills add compozy/compozy --skill assistant-ui-runtime -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install compozy/compozy assistant-ui-runtime --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/compozy/compozy.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/assistant-ui/assistant-ui-runtime .cursor/skills/assistant-ui-runtime && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "assistant-ui-runtime" agent skill from https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime into .cursor/skills/assistant-ui-runtime/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "assistant-ui-runtime", 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

$ gemini skills install https://github.com/compozy/compozy.git --path .agents/skills/assistant-ui/assistant-ui-runtime

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add compozy/compozy --skill assistant-ui-runtime -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install compozy/compozy assistant-ui-runtime --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/compozy/compozy.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/assistant-ui/assistant-ui-runtime .gemini/skills/assistant-ui-runtime && rm -rf skills-src

Use ~/.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/

Paste into Gemini CLI

Install the "assistant-ui-runtime" agent skill from https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime into .gemini/skills/assistant-ui-runtime/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "assistant-ui-runtime", 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.

GitHub CLI

$ gh skill install compozy/compozy assistant-ui-runtime

Installs 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).

skills CLI

$ npx skills add compozy/compozy --skill assistant-ui-runtime -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/compozy/compozy.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/assistant-ui/assistant-ui-runtime .github/skills/assistant-ui-runtime && rm -rf skills-src

Use ~/.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/

Paste into GitHub Copilot

Install the "assistant-ui-runtime" agent skill from https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime into .github/skills/assistant-ui-runtime/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "assistant-ui-runtime", 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.

skills CLI

$ npx skills add compozy/compozy --skill assistant-ui-runtime -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install compozy/compozy assistant-ui-runtime --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/compozy/compozy.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/assistant-ui/assistant-ui-runtime .opencode/skills/assistant-ui-runtime && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "assistant-ui-runtime" agent skill from https://github.com/compozy/compozy/tree/main/.agents/skills/assistant-ui/assistant-ui-runtime into .opencode/skills/assistant-ui-runtime/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "assistant-ui-runtime", 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: assistant-ui-runtime
GitHub stars: 2.8k
Token cost: ~856 tokens
SKILL.md length: 77 words
Files: 6 (incl. references)
Skills in repo: 47
Repo updated: Oct 8, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Guide for assistant-ui runtime system and state management. An agent skill from compozy/compozy.

Working with runtimes
SKILL.md covers References, Runtime Hierarchy, State Access (Modern API) and Thread Operations, plus 5 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
Accessing state

What it does

Assistant UI Runtime is an agent skill from compozy/compozy. Guide for assistant-ui runtime system and state management. Use when working with runtimes, accessing state, or managing thread/message data.

Its SKILL.md is about 860 tokens, which your agent loads only when the skill is triggered. The skill folder holds 6 other files, including reference files (for example `references/external-store.md`, `references/local-runtime.md` and `references/state-hooks.md`).

It sits in Frontend & Design, covering State management. The repository describes itself as: An operating system for AI agents. Plug in the agent CLIs you already use (Claude Code, Codex, Gemini CLI, Cursor) and they become a team: they split the work, hand tasks to each… The licence is MIT.

When your agent uses it

Working with runtimes
Accessing state
Managing thread/message data

Example prompts

“/assistant-ui-runtime”

What it can do on your machine

Read from SKILL.md and the folder at commit eec2ed1. 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):
- assistant-ui.com
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

Assistant UI Runtime loads about 856 tokens when it runs, and up to ~8.7k if it reads all its reference files. Until then it costs about 41 tokens; SKILL.md has 77 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~41
When it runs · the whole SKILL.md, loaded when a task matches: ~856
With references · SKILL.md plus every file in references/, read only if the agent opens them: ~8.7k

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

The full file from compozy/compozy at commit eec2ed1, republished under its MIT licence (© compozy). 77 words, ~856 tokens.

Download SKILL.mdSave it as .claude/skills/assistant-ui-runtime/SKILL.md (or your agent's skills folder). This skill also uses 5 other files; get the full folder from GitHub.

name: assistant-ui-runtime
description: Guide for assistant-ui runtime system and state management. Use when working with runtimes, accessing state, or managing thread/message data.
version: 0.0.1
license: MIT

assistant-ui Runtime

Always consult assistant-ui.com/llms.txt for latest API.

References

./references/local-runtime.md -- useLocalRuntime deep dive
./references/external-store.md -- useExternalStoreRuntime deep dive
./references/thread-list.md -- Thread list management
./references/state-hooks.md -- State access hooks
./references/types.md -- Type definitions

Runtime Hierarchy

AssistantRuntime
├── ThreadListRuntime (thread management)
│   ├── ThreadListItemRuntime (per-thread item)
│   └── ...
└── ThreadRuntime (current thread)
    ├── ComposerRuntime (input state)
    └── MessageRuntime[] (per-message)
        └── MessagePartRuntime[] (per-content-part)

State Access (Modern API)

tsx

import { useAui, useAuiState, useAuiEvent } from "@assistant-ui/react";

function ChatControls() {
  const api = useAui();
  const messages = useAuiState(s => s.thread.messages);
  const isRunning = useAuiState(s => s.thread.isRunning);

  useAuiEvent("composer.send", (e) => {
    console.log("Sent in thread:", e.threadId);
  });

  return (
    <div>
      <button onClick={() => api.thread().append({
        role: "user",
        content: [{ type: "text", text: "Hello!" }],
      })}>
        Send
      </button>
      {isRunning && (
        <button onClick={() => api.thread().cancelRun()}>Cancel</button>
      )}
    </div>
  );
}

Thread Operations

tsx

const api = useAui();
const thread = api.thread();

// Append message
thread.append({ role: "user", content: [{ type: "text", text: "Hello" }] });

// Cancel generation
thread.cancelRun();

// Get current state
const state = thread.getState();  // { messages, isRunning, ... }

Message Operations

tsx

const message = api.thread().message(0);  // By index

message.edit({ role: "user", content: [{ type: "text", text: "Updated" }] });
message.reload();

Events

tsx

useAuiEvent("thread.runStart", () => {});
useAuiEvent("thread.runEnd", () => {});
useAuiEvent("composer.send", ({ threadId }) => {
  console.log("Sent in thread:", threadId);
});
useAuiEvent("thread.modelContextUpdate", () => {});

Capabilities

tsx

const caps = useAuiState(s => s.thread.capabilities);
// { cancel, edit, reload, copy, speak, attachments }

Quick Reference

tsx

// Get messages
const messages = useAuiState(s => s.thread.messages);

// Check running state
const isRunning = useAuiState(s => s.thread.isRunning);

// Append message
api.thread().append({ role: "user", content: [{ type: "text", text: "Hi" }] });

// Cancel generation
api.thread().cancelRun();

// Edit message
api.thread().message(index).edit({ ... });

// Reload message
api.thread().message(index).reload();

Common Gotchas

"Cannot read property of undefined"

Ensure hooks are called inside AssistantRuntimeProvider

State not updating

Use selectors with useAuiState to prevent unnecessary re-renders

Messages array empty

Check runtime is configured
Verify API response format

Files

SKILL.md and 5 other files (references) in .agents/skills/assistant-ui/assistant-ui-runtime of compozy/compozy.

SKILL.md
references/external-store.md
references/local-runtime.md
references/state-hooks.md
references/thread-list.md
references/types.md

Open the folder on GitHubat commit eec2ed1

Compare with similar skills

Assistant UI Runtime 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.

Assistant UI Runtime compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Assistant UI Runtime this skillcompozy/compozy	2.8k	—	~856	Automated safety check: Pass	MIT	today
Svelte Core Best Practicesrilldata/rill	2.9k	4 repos	~1.8k	Automated safety check: Pass	Apache-2.0	yesterday
Dify Component Writing Guidelanggenius/dify	158k	—	~626	Automated safety check: Pass	Custom licence	today
React State Managementinvolvex/youtube-music-cli	456	13 repos	~3k	Automated safety check: Pass	MIT	today
GPUI Kit Desktop App GuideAprilNEA/OpenLogi	23k	—	~5.5k	Automated safety check: Pass	Apache-2.0	4 days ago
Pierre Theming Librarypierrecomputer/pierre	6.2k	—	~661	Automated safety check: Pass	Apache-2.0	today

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Questions about Assistant UI Runtime

What does Assistant UI Runtime do?

Guide for assistant-ui runtime system and state management. An agent skill from compozy/compozy. Assistant UI Runtime is an agent skill from compozy/compozy. Guide for assistant-ui runtime system and state management.

When should I use Assistant UI Runtime?

Assistant UI Runtime fits situations like: working with runtimes; accessing state; managing thread/message data.

How do I install Assistant UI Runtime in Claude Code?

Run `npx skills add compozy/compozy --skill assistant-ui-runtime -a claude-code`. Or copy the skill folder (.agents/skills/assistant-ui/assistant-ui-runtime in compozy/compozy) into .claude/skills/assistant-ui-runtime in your project. Claude Code loads it when a task matches its description.

How do I install Assistant UI Runtime in Codex?

Run `npx skills add compozy/compozy --skill assistant-ui-runtime -a codex`. Or copy the skill folder (.agents/skills/assistant-ui/assistant-ui-runtime in compozy/compozy) into .agents/skills/assistant-ui-runtime in your project. Codex loads it when a task matches its description.

Can I use Assistant UI Runtime 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 compozy/compozy --skill assistant-ui-runtime -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/assistant-ui-runtime, .gemini/skills/assistant-ui-runtime, .github/skills/assistant-ui-runtime and .opencode/skills/assistant-ui-runtime in your project.

What does Assistant UI Runtime need to run?

SKILL.md names no scripts, command-line tools or credentials: Assistant UI Runtime is instructions for the agent only.

Does Assistant UI Runtime access the network?

SKILL.md names 1 domain. As links in the text: assistant-ui.com. This is read from the text; nothing was executed.

Is Assistant UI Runtime 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 Assistant UI Runtime use?

Assistant UI Runtime is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Assistant UI Runtime use?

About 856 tokens (SKILL.md is roughly 3.4k 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 7.8k tokens, read only when the agent opens those files.

What are the alternatives to Assistant UI Runtime?

Skills that share tags, products or a category with Assistant UI Runtime: Svelte Core Best Practices (rilldata/rill, 2.9k stars), Dify Component Writing Guide (langgenius/dify, 158k stars), React State Management (involvex/youtube-music-cli, 456 stars) and GPUI Kit Desktop App Guide (AprilNEA/OpenLogi, 23k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Assistant UI Runtime?

compozy (a GitHub organization) maintains it in compozy/compozy, which has 2,792 GitHub stars. The repository holds 47 skills in this directory. The repository was last updated on October 8, 2026.

Source: compozy/compozy on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Assistant UI Runtime

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

assistant-ui Runtime

References

Runtime Hierarchy

State Access (Modern API)

Thread Operations

Message Operations

Events

Capabilities

Quick Reference

Common Gotchas

Files

Compare with similar skills

Similar skills

More from compozy/compozy

Related

Questions about Assistant UI Runtime