Feature Request: Extension API for third-party VS Code extensions

Summary

Currently, Claude Code's VS Code extension is a closed system — other VS Code extensions cannot programmatically interact with it. While MCP servers, hooks, and skills extend what Claude can do, there is no way for third-party extensions to extend the Claude Code UI or interact with it directly within VS Code.

Motivation

Developers building complementary VS Code extensions (e.g., prompt managers, project-specific tooling, workflow automation) would benefit greatly from being able to integrate with Claude Code at the VS Code extension level. Right now the only options are:

• Build beside it — a separate VS Code extension with no direct communication
• Build under it — MCP servers that Claude Code can call, but with no UI control

This limits the ecosystem and forces workarounds for common use cases.

Proposed Capabilities

An Extension API could enable third-party VS Code extensions to:

• Send prompts programmatically — queue and execute prompts from another extension
• Subscribe to events — react to Claude Code lifecycle events (prompt started, completed, permission requested, etc.) directly in VS Code, not just via CLI hooks
• Inject UI elements — add custom buttons, menu items, or panel sections into the Claude Code interface
• Read state — check if Claude is busy, what the current session status is, etc.
• Sequential prompt queues — submit a list of prompts to be executed one after another
• Two-way communication — allow external UIs (mobile apps, web dashboards) to respond to Claude Code's questions/permission requests

Use Cases

1. Prompt management tools — extensions that maintain libraries of prompts and feed them to Claude Code
2. Mobile notifications & approvals — route Claude's questions to a phone, receive answers back
3. Workflow orchestration — run a defined sequence of prompts, each waiting for the previous to complete
4. Project-specific tooling — custom UI panels that interact with Claude Code based on project context
5. Team dashboards — monitor and interact with Claude Code sessions from external interfaces

Current Workarounds

• Using Claude Code CLI (claude --print) for non-interactive prompt execution
• Using hooks for one-way event notifications
• Building completely separate VS Code extensions that don't communicate with Claude Code

All of these are limited compared to a proper Extension API.

Suggestion

Expose a VS Code extension API (via vscode.extensions.getExtension('anthropic.claude-code')?.exports) that other extensions can consume. This is a standard VS Code pattern used by extensions like GitLens, ESLint, and others.

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This would open up Claude Code to a community-driven ecosystem of integrations directly within VS Code.