Support per-agent LSP server configuration in agent frontmatter

[michaelBenin]

Feature request

Is your feature request related to a problem?

I am building a multi-agent system where each agent has a different specialization. Agents already support per-agent MCP server configs via mcp-servers in the YAML frontmatter, which is excellent — each agent only sees the external tools it needs.

However, LSP servers are configured globally (user-level ~/.copilot/lsp-config.json or repo-level .github/lsp.json). There is no way to scope LSP servers to a specific agent.

This matters because different agents work with different languages and file types:

• A morning-command-center agent works primarily with Markdown and YAML (agent definitions, skill files, documentation). It needs yaml-language-server but has no use for typescript-language-server.
• A deep-work-planner agent investigates codebases and would benefit from TypeScript, Python, and SQL LSP servers for code navigation.
• A communication-triage agent classifies messages and drafts responses — it has no need for any LSP server at all.

With global-only LSP config, every agent loads every configured LSP server regardless of whether it will use them. This wastes resources and increases startup time, especially when you have 7+ agents and 9+ LSP servers configured globally.

Describe the solution you would like

Allow agents to declare LSP servers in their .agent.md frontmatter, similar to mcp-servers:

---
name: deep-work-planner
lsp-servers:
  typescript:
    command: npx
    args: ["--yes", "typescript-language-server", "--stdio"]
    fileExtensions:
      .ts: typescript
      .tsx: typescript
  python-typecheck:
    command: npx
    args: ["--yes", "pyright-langserver", "--stdio"]
    fileExtensions:
      .py: python
---

When an agent declares lsp-servers, only those LSP servers would be started for that agent session. If no lsp-servers block is present, fall back to the existing global/repo config.

Describe alternatives you have considered

• Maintaining separate repo-level .github/lsp.json files per project — but this does not solve per-agent isolation within the same repo.
• Not configuring LSP servers globally and relying only on agents that need them — but this breaks the default CLI experience outside of agents.

Additional context

This would bring LSP config parity with MCP config, which already supports per-agent scoping. The pattern is already established in the agent frontmatter format — this would extend it to LSP.