LSP server not found when configured via project-level .github/lsp.json

[martinikf]

Describe the bug

GitHub Copilot CLI fails to locate or initialize LSP servers when they are defined in a project-specific .github/lsp.json file, even though the CLI correctly detects the file's presence. The same configuration works perfectly when placed in the global ~/.copilot/lsp-config.json.

Not working example in .github/lsp.json

/lsp

 LSP Server Status:
  Project-configured servers:
    • typescript: (.ts, .tsx)

  User config: C:\Users\user\.copilot\lsp-config.json
  Project config: C:\project\.github\lsp.json

/lsp test typescript
✗ Server "typescript" not found. Available: (none) 

Lsp works correctly if cofigured in: .~/.copilot/lsp-config.json.

User-configured servers:
  • typescript: typescript-language-server (.ts, .tsx)

User config: C:\Users\user\.copilot\lsp-config.json

 ✓ Server "typescript" started successfully!

    PID: 24812
    Spawn time: 20ms

  Server was killed after successful test.

Affected version

1.0.12

Steps to reproduce the behavior

1. Configure lsp in .github/lsp.json
2. Start copilot
3. /lsp test lsp-name

Expected behavior

LSP server should start successfully.

Additional context

Used config:

{
    "lspServers": {
        "typescript": {
            "command": "typescript-language-server",
            "args": ["--stdio"],
            "fileExtensions": {
                ".ts": "typescript",
                ".tsx": "typescript"
            }
        }
    }   
}

Windows 11, Terminal, Powershell7