Shell tool environment does not inherit user PATH - Nix-managed binaries unavailable in sessions

[danielsogl]

Describe the bug

In worktree-backed sessions, the bash tool runs with a minimal PATH that does not include paths configured via launchd.user.envVariables or /etc/profiles/per-user/$USER/bin.

On macOS with Nix (nix-darwin + home-manager), binaries like gh are installed at /etc/profiles/per-user/daniel/bin/gh but are not reachable inside sessions. The shell only sees:

/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin

The environment_context block in sessions also documents this limitation explicitly:

Available tools: git, curl

There is currently no way to extend or configure additional paths for the session shell.

Affected version

Steps to reproduce the behavior

1. Install gh via Nix on macOS (nix-darwin + home-manager), binary lands at /etc/profiles/per-user/$USER/bin/gh
2. Open a Copilot CLI worktree session
3. Run which gh or gh --version in the bash tool
4. Command fails with command not found

Expected behavior

The session shell should inherit the user's launchd environment PATH (set via launchd.user.envVariables), or provide a way to configure additional PATH entries (e.g. via .copilot/config.json).

Additional context

• macOS aarch64 (Apple Silicon)
• Package manager: nix-darwin + home-manager
• gh present at /etc/profiles/per-user/daniel/bin/gh
• PATH is correctly set for all other GUI apps and terminals after launchd.user.envVariables is only Copilot CLI sessions are affectedconfigured
• Workaround: call binaries via absolute path (fragile, not documented)