/desktop fails on Windows: deep-link URL split on ampersand by cmd.exe

/desktop fails on Windows — deep-link URL is split on & by cmd.exe

Summary

On Windows, the /desktop (alias /app) slash command always fails with:

Error: Failed to open Claude Desktop. Please try opening it manually.

The error message is misleading. The Claude Desktop app, the claude:// protocol handler, and authentication are all correct. The actual problem is that the CLI launches the claude://resume?session=…&cwd=… deep link through cmd.exe, which interprets the unescaped & as a command separator. The URL is split in half, so an incomplete link is dispatched and the handoff fails.

Environment

• OS: Windows 11 Pro (10.0.26200)
• Claude Code: 2.1.168 (native installer, %USERPROFILE%\.local\bin\claude.exe)
• Claude Desktop: 1.11187.4.0 (installed, Status: Ok)
• Shell: PowerShell

Verified: setup is correct

Protocol handler is registered and points to a valid exe:

HKCU:\Software\Classes\claude        -> "C:\Program Files\WindowsApps\Claude_1.11187.4.0_x64__pzs8sxrjxfjjc\app\Claude.exe" "%1"
HKCU:\Software\Classes\claude-cli     -> "C:\Users\<user>\.local\bin\claude.exe" --handle-uri "%1"

Root cause (minimal repro)

The deep link contains &. When passed through cmd.exe, it splits:

PS> cmd /c "echo claude://resume?session=ABC123&cwd=C:\Users\me"
claude://resume?session=ABC123
'cwd' is not recognized as an internal or external command,
operable program or batch file.

So the launcher effectively runs:

1. start "" "claude://resume?session=ABC123" ← incomplete URL → fails to resolve
2. cwd=C:\Users\me ← treated as a separate command → error (swallowed)

Result: "Failed to open Claude Desktop."

Confirmation that the handoff target works

Launching the same URL via a method that does not let cmd.exe re-parse it succeeds and opens the session in the desktop app:

$session = '<session-id>'
$cwd = [uri]::EscapeDataString('D:\Claude Code')
Start-Process "claude://resume?session=$session&cwd=$cwd"   # works, desktop app resumes the session

Expected behavior

/desktop opens the Claude Desktop app and resumes the current session.

Suggested fix

On Windows, don't route the deep link through cmd /c start "…" with an unescaped URL. Either:

• launch it without a shell (e.g. spawn with shell: false), or
• use PowerShell Start-Process "<url>", or
• escape & as ^& for the cmd path.