[BUG] LSP tool doesn't recognize plugin-based LSP server configurations

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The LSP tool returns "No LSP server available for file type: .swift" (and similarly for .ts, .dart) even though LSP plugins are properly installed and enabled.

Environment:

• Claude Code version: 2.0.76
• OS: macOS Darwin 24.6.0
• sourcekit-lsp: /usr/bin/sourcekit-lsp (installed via Xcode)

Installed LSP Plugins:
{
"swift-lsp@claude-plugins-official": true,
"typescript-lsp@claude-plugins-official": true,
"dart-analyzer@claude-code-lsps": true
}

Plugin Configuration (.lsp.json):
{
"swift": {
"command": "sourcekit-lsp",
"args": [],
"extensionToLanguage": {
".swift": "swift"
}
}
}

Steps to Reproduce:

1. Install swift-lsp plugin via claude /plugin install swift-lsp@claude-plugins-official
2. Verify plugin is enabled in ~/.claude/settings.json
3. Use LSP tool on a .swift file

What Should Happen?

LSP operations work (documentSymbol, goToDefinition, etc.)

Error Messages/Logs

No LSP server available for file type: .swift

Steps to Reproduce

1. Install swift-lsp plugin via claude /plugin install swift-lsp@claude-plugins-official
2. Verify plugin is enabled in ~/.claude/settings.json
3. Use LSP tool on a .swift file

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_