chat-participant-patterns

chat-participant-patterns is a skill for Claude Code, Codex from fabioc-aloha/Alex_Skill_Mall. It costs 12 tokens per session (1,792 once invoked), scanned A, original, MIT.

A pattern guide for building chat participants in Visual Studio Code, where developers interact with extensions through chat. It also explains when to use a chat participant, an automatic tool, an agent skill, or an MCP server.

In plain words
What is it for?
Creating and configuring VS Code chat participants, including their package contributions and implementation. It is also for deciding how to add domain knowledge, automatic actions, or cross-platform tools to an extension.
Why use it?
It helps extension authors choose the right VS Code integration and avoid using a chat participant when another approach fits better. It also accounts for changes in recent VS Code chat APIs.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Creating and configuring VS Code chat participants, including their package contributions and implementation. It is also for deciding how to add domain knowledge, automatic actions, or cross-platform tools to an extension.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add fabioc-aloha/Alex_Skill_Mall --skill chat-participant-patterns
Clone the repo
git clone --depth 1 https://github.com/fabioc-aloha/Alex_Skill_Mall

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for chat-participant-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns/github.svg)](https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns)
Your own site
<a href="https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns"><img src="https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for chat-participant-patterns

Your own site · 80×15
<a href="https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns"><img src="https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/chat-participant-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 12 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,792 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00012 $0.01792
Opus 5 $0.00006 $0.00896
Sonnet 5 $0.00002 $0.00358
Haiku 4.5 $0.00001 $0.00179

Measured 11d ago against content hash dd9159548cb0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

chat-participant-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/ai-agents/chat-participant-patterns/skills/chat-participant-patterns/SKILL.md · 204 lines

How it starts

The opening of the file, as written. The whole thing — 204 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Chat Participant Patterns Skill

VS Code Chat API patterns.

⚠️ Staleness Warning

Chat APIs evolve with VS Code releases. Last validated: March 2026 (VS Code 1.111+)

Check: Chat API, LM API, Tools API, AI Extensibility Overview, EXTERNAL-API-REGISTRY.md


When to Use Chat Participant vs. Skills/Tools

Approach Use When VS Code API
Chat Participant Need full control of prompt + response, domain-specific @-mention vscode.chat.createChatParticipant
LM Tool Domain capability invoked automatically in agent sessions vscode.lm.registerTool
Agent Skill (SKILL.md) Domain knowledge embedded into any agent session (no code) chat.useAgentSkills + SKILL.md file
MCP Server Cross-platform tool providing data/actions to any MCP client MCP SDK

→ Prefer Skills for domain knowledge. Reserve participants for full prompt orchestration.


Create Participant

// package.json contribution
"contributes": {
    "chatParticipants": [{
        "id": "my-ext.participant",
        "name": "myparticipant",
        "fullName": "My Participant",
        "description": "What can I help with?",
        "isSticky": true,
        "commands": [{ "name": "help", "description": "Get help" }]
    }]
}

// In activate()
const participant = vscode.chat.createChatParticipant('my-ext.participant', handler);
participant.iconPath = vscode.Uri.joinPath(context.extensionUri, 'icon.png');

Handler Signature

const handler: vscode.ChatRequestHandler = async (
    request: vscode.ChatRequest,
    context: vscode.ChatContext,
    stream: vscode.ChatResponseStream,
    token: vscode.CancellationToken
): Promise<IChatResult> => {
    // Handle request
};

Read the full file on GitHub · 204 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 11d ago First seen · 204 lines · 12 tokens per session scan A dd9159548cb0

Subscribe to this mod's changes

chat-participant-patterns is a skill published in the GitHub repository fabioc-aloha/Alex_Skill_Mall (4 stars, last pushed today), licensed MIT. It adds 12 tokens to every session and 1,792 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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