Cowork fails on Apple Silicon M5 - hardcoded /usr/bin/bash path does not exist after Intel Mac migration

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork fails to launch on MacBook Air M5 (Apple Silicon). It is hardcoded to run /usr/local/bin/claude using /usr/bin/bash, but /usr/bin/bash does not exist on my Mac (macOS blocks creating it via SIP). This error appears every time: "CLI output was not valid JSON. This may indicate an error during startup. Output: /usr/bin/bash: line 1: /usr/local/bin/claude: cannot execute binary file: Exec format error"

What Should Happen?

Cowork should launch successfully and run the Claude CLI using the correct shell path (/bin/bash) on Apple Silicon Macs.

Error Messages/Logs

CLI output was not valid JSON. This may indicate an error during startup. Output: /usr/bin/bash: line 1: /usr/local/bin/claude: cannot execute binary file: Exec format error

Steps to Reproduce

1. Migrate from Intel MacBook Pro to Apple Silicon MacBook Air M5
2. Install Claude CLI via: sudo npm install -g @anthropic-ai/claude-code
3. Open Cowork app
4. Error appears immediately: "CLI output was not valid JSON. /usr/bin/bash: line 1: /usr/local/bin/claude: cannot execute binary file: Exec format error"

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Worked on previous Intel MacBook Pro, broke after migrating to M5

Claude Code Version

2.1.81 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Migrated from Intel MacBook Pro to MacBook Air M5. Cowork is hardcoded to use /usr/bin/bash which does not exist on this Mac (real bash is at /bin/bash). macOS SIP prevents creating a symlink to fix it. Tried every workaround including downloading ARM64 binary directly, creating wrapper scripts, reinstalling Node.js and Claude CLI. The CLI works fine in Terminal (claude --version returns 2.1.81) but Cowork cannot launch it. This requires a fix inside the Cowork app itself.