Specific bash commands fail on Windows in Git Bash due to path re-mapping #4379

Description

When running opencode from a git bash shell session on Windows, cd, rm, cp, mv, mkdir, touch, chmod and chown always result in:

This command references paths outside of ${Instance.directory} so it is not allowed to be executed.

This is due to how git bash remaps Windows-style paths to Unix style paths. See https://github.com/sst/opencode/blob/1e6589526d36b814e8af30a81932d0e9967c64ac/packages/opencode/src/tool/bash.ts#L92. The resolved path will be something like /c/Users/bob/workspace but the instance path will be a Windows-style path like C:\Users\bob\workspace causing the check to fail and the command to be rejected.

OpenCode version

1.0.65

Steps to reproduce

Issue a prompt like "Run cd src && ls and show me the output".

Screenshot and/or share link

Operating System

Windows 11

Terminal

Windows Terminal