[Bug] LSP plugin fails to spawn npm-installed .cmd binaries on Windows

Bug Description
LSP plugin fails to spawn .cmd binaries on Windows (npm-installed language servers) ## Description On Windows, LSP plugins (e.g., pyright-lsp, typescript-lsp) fail to spawn language server binaries that are installed via npm with .cmd extension. ## Environment - Claude Code version: 2.1.119 - OS: Windows 10/11 - Shell: PowerShell - Node.js installed via standard installer - npm global directory: %APPDATA%\npm ## Reproduction Steps 1. Install Claude Code v2.1.119 on Windows 2. Install LSP plugins via /plugin install pyright-lsp@claude-plugins-official and typescript-lsp@claude-plugins-official 3. Install language server binaries via npm: npm install -g pyright typescript-language-server typescript 4. Verify binary exists: where.exe pyright-langserver.cmd returns C:\Users\<user>\AppData\Roaming\npm\pyright-langserver.cmd 5. Try LSP hover operation in Claude Code ## Expected Behavior LSP hover/find references/etc. should work using the .cmd binary. ## Actual Behavior Error performing hover: ENOENT: no such file or directory, uv_spawn 'pyright-langserver' The uv_spawn call attempts to spawn 'pyright-langserver' (without extension) but does not fall back to .cmd on Windows. ## Verification where.exe pyright-langserver returns no output (the extensionless file is a Unix shell script, not executable on Windows). where.exe pyright-langserver.cmd returns the correct path. The npm install creates three files in the npm global directory: - pyright-langserver (Unix shell script, not executable on Windows) - pyright-langserver.cmd (Windows batch file, the working entry point) - pyright-langserver.ps1 (PowerShell script) Claude Code only attempts the extensionless name, which fails on Windows. ## Workarounds Tried 1. Adding %APPDATA%\npm to PATH: already in PATH 2. Restarting Claude Code session: no effect 3. Using pipx install pyright instead of npm: would work for Python only, not for TypeScript 4. Editing marketplace.json to use .cmd explicitly: works but reverts on plugin updates ## Suggested Fix On Windows, the spawn logic should: 1. First try the extensionless command name 2. If that fails with ENOENT, automatically try with .cmd and .exe extensions (matching PATHEXT behavior) This matches how cmd.exe and PowerShell resolve commands. ## Impact This affects all npm-installed LSP servers on Windows (pyright, typescript-language-server, vue-language-server, etc.). Many Windows developers using Claude Code are likely affected.

Environment Info

• Platform: win32
• Terminal: windows-terminal
• Version: 2.1.119
• Feedback ID: 21be9bb2-7429-4aec-845b-4610184511b1

Errors

[{"error":"Error: LSP server plugin:pyright-lsp:pyright failed to start: ENOENT: no such file or directory, uv_spawn 'pyright-langserver'\n    at start (B:/~BUN/root/src/entrypoints/cli.js:3220:22157)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-27T06:26:45.326Z"},{"error":"Error: ENOENT: no such file or directory, uv_spawn 'pyright-langserver'\n    at spawn (unknown)\n    at spawn (node:child_process:679:35)\n    at spawn (node:child_process:14:39)\n    at start (B:/~BUN/root/src/entrypoints/cli.js:3220:20693)\n    at M (B:/~BUN/root/src/entrypoints/cli.js:3220:24676)\n    at Y (B:/~BUN/root/src/entrypoints/cli.js:3220:29916)\n    at w (B:/~BUN/root/src/entrypoints/cli.js:3220:30301)\n    at call (B:/~BUN/root/src/entrypoints/cli.js:3716:5730)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-27T06:26:45.326Z"},{"error":"Error: Failed to start LSP server for file C:\\Users\\nk-qc-00\\Desktop\\nk-pms\\backend\\app\\api\\jisseki.py: ENOENT: no such file or directory, uv_spawn 'pyright-langserver'\n    at Y (B:/~BUN/root/src/entrypoints/cli.js:3220:29942)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-27T06:26:45.326Z"},{"error":"Error: LSP tool request failed for hover on backend/app/api/jisseki.py: ENOENT: no such file or directory, uv_spawn 'pyright-langserver'\n    at call (B:/~BUN/root/src/entrypoints/cli.js:3716:7173)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-27T06:26:45.327Z"},{"error":"Error: LSP server plugin:pyright-lsp:pyright failed to start: ENOENT: no such file or directory, uv_spawn 'pyright-langserver'\n    at start (B:/~BUN/root/src/entrypoints/cli.js:3220:22157)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-27T06:35:16.996Z"},{"error":"Error: ENOENT: no such file or directory, uv_spawn 'pyright-langserver'\n    at spawn (unknown)\n    at spawn (node:child_process:679:35)\n    at spawn (node:child_process:14:39)\n    at start (B:/~BUN/root/src/entrypoints/cli.js:3220:20693)\n    at M (B:/~BUN/root/src/entrypoints/cli.js:3220:24676)\n    at Y (B:/~BUN/root/src/entrypoints/cli.js:3220:29916)\n    at w (B:/~BUN/root/src/entrypoints/cli.js:3220:30301)\n    at call (B:/~BUN/root/src/entrypoints/cli.js:3716:5730)\n    at processTicksAndRejections (native:7:39)…

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