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Julia LSP call fails silently for agents #2229

Description

@termi-official

Describe the bug

/lsp test julia works, but if an agent tries to access the LSP I just see an exit code in the logs (in .copilot/logs) . I.e.

2026-03-23T14:39:26.107Z [INFO] --- Start of group: Sending request to the AI model ---
2026-03-23T14:39:29.662Z [ERROR] LSP julia server for <path-to-project>: LSP server exited with code 1

where I masked . Manually launching the LSP works fine.

Affected version

GitHub Copilot CLI 1.0.10.

Steps to reproduce the behavior

Install a language-server, e.g. via julia --project=~/.julia/environments/languageserver -e 'using Pkg; Pkg.add("LanguageServer"); Pkg.add("SymbolServer")'
Add for example

{
    "lspServers": {
        "julia": {
            "command": "julia",
            "args": [
                "--project=~/.julia/environments/languageserver",
                "-e",
                "using LanguageServer, SymbolServer; runserver()"
            ],
            "fileExtensions": {
                ".jl": "julia"
            }
        }
    }
}

to ~/.copilot/lsp-config.json. Expanding the paths to full paths (i.e. as /home/... also does not work.

Expected behavior

The LSP should not error. The failure should give at least some meaningful message in the logs.

Additional context

Operating system is an up-to-date arch linux, if relevant.

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    area:agentsSub-agents, fleet, autopilot, plan mode, background agents, and custom agentsarea:toolsBuilt-in tools: file editing, shell, search, LSP, git, and tool call behavior

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