chat-participant-patterns

# 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](https://code.visualstudio.com/api/extension-guides/ai/chat), [LM API](https://code.visualstudio.com/api/extension-guides/ai/language-model), [Tools API](https://code.visualstudio.com/api/extension-guides/ai/tools), [AI Extensibility Overview](https://code.visualstudio.com/api/extension-guides/ai/ai-extensibility-overview), [EXTERNAL-API-REGISTRY.md](../../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 ```typescript // package.json contribution "contributes": { "chatParticipants": [{ "id": "my-ext.participant", "name": "myparticipant", "fullName": "My Participant", "...