Shell Detection for Non-POSIX Shells (Nushell, Fish)

[ramarivera]

Summary

ClaudeBar's binary locator should support users whose default shell is Nushell, Fish, or other non-POSIX shells.

Problem

BinaryLocator currently assumes POSIX shell syntax when running which and reading $PATH. Users with Nushell as their login shell experience failures because:

• Nushell's built-in which outputs tables instead of plain paths
• Nushell uses $env.PATH (a list) instead of $PATH (a colon-separated string)

This prevents ClaudeBar from finding CLI tools installed via nix-darwin, Homebrew, or other package managers for Nushell users.

Proposed Solution

Introduce a Shell enum that encapsulates shell-specific behavior:

1. Detect shell type from $SHELL environment variable
2. Generate appropriate which command syntax per shell
3. Generate appropriate PATH retrieval command per shell
4. Parse shell-specific output formats

Supported Shells

Shell	which Command	PATH Command
POSIX (bash, zsh)	which <tool>	echo $PATH
Fish	which <tool>	echo $PATH
Nushell	^which <tool>	$env.PATH | str join ':'

Acceptance Criteria

• Shell type detected from $SHELL environment variable
• Nushell users can locate CLI tools correctly
• Fish users can locate CLI tools correctly
• POSIX shells continue to work as before
• Unknown shells default to POSIX behavior
• Unit tests cover all shell types and parsing scenarios

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🤖 This issue was generated with AI assistance using Claude Opus 4.5 (latest).