File paths resolved from server's cwd instead of client's cwd when using opencode attach #4966

Description

When running opencode server in one directory and using opencode attach from a different directory, file references (using @ syntax) are resolved relative to the server's working directory instead of the client's current working directory.

This makes it difficult to work with multiple projects while running a single server instance.

Steps to reproduce

1. Start the server from a parent directory:

   cd ~/Development
   opencode

2. From another terminal, navigate to a subdirectory and attach:

   cd ~/Development/saturdays/saturdays
   opencode attach

3. Try to reference a file that exists in the client's cwd:

   @docs/report.md
   

4. Server throws ENOENT because it looks for the file at ~/Development/docs/report.md instead of ~/Development/saturdays/saturdays/docs/report.md

Error

ENOENT: no such file or directory, stat '/Users/an/Development/saturdays/saturdays/docs/1_report.md'
    path: "/Users/an/Development/saturdays/saturdays/docs/1_report.md",
 syscall: "stat",
   errno: -2,
    code: "ENOENT"

Expected behavior

When using opencode attach, the client should pass its current working directory to the server, and file paths should be resolved relative to the client's cwd (or allow switching workspace context).

Use case

Running a single OpenCode server instance and attaching from different project directories without needing to restart the server or use absolute paths for every file reference.

Possible solutions

1. Pass client's cwd to server on attach and use it for path resolution
2. Add a command like /cd or /workspace to switch the server's working directory context
3. Support workspace/project switching within a single server session

Related

• TUI sends absolute local paths causing ENOENT on server side #4686 (similar issue but for remote Windows -> Linux scenario)

Environment

• OpenCode version: 1.0.x
• OS: macOS
• Terminal: Any