agents will create empty folders it didn't mean to when using `mkdir -p {src,test,...}`

[riatzukiza]

Description

When some models want to create many folders all at once they'll use the syntax:

mkdir -p src/{folder1,folder2,folder3}`

and it will literally create a folder src/{folder1,folder2,folder3}

OpenCode version

0.15.11

Steps to reproduce

as an agent (I've been using big pickle and glm-4.6) to scaffold a module that will require it to create many directories, like trying to consolidate or move several modules

Screenshot and/or share link

No response

Operating System

Ubuntu 24.04

Terminal

Alacritty

[rekram1-node]

Hm never encountered this

[veracioux]

The a/{x,y,z} syntax is called cartesian product and it's not supported by every shell. Since we use the shell from $SHELL to run the commands, the variable probably points to a lesser-featured shell like dash.

@riatzukiza Can you run echo $SHELL in the terminal where you run opencode, and tell me what it prints?

[veracioux]

Actually, I was wrong here (when writing that comment I was thinking about the ! command invocation). It does in fact use /bin/sh, which almost certainly lacks the cartesian product functionality. This issue suggests an implementation which would actually make opencode behave in the way I described in my previous comment: #3479

@rekram1-node Perhaps we can consider implementing the suggestion from #3479, or at least indicate in the system prompt what shell it's dealing with, so it knows to avoid certain capabilities.

[rekram1-node]

I think implementing suggestion > indicate in system prompt.

We should make it bash if possible but need to handle windows otherwise

Don't like all unix systems support bash basically? i guess it doesnt hurt to add a check

[veracioux]

I think they do, but we might also want to support containerized use cases like alpine, so a check is a good idea.

[Br1an67]

I'd like to work on this. The root cause is that Shell.acceptable() passes through POSIX-only shells (sh/dash) which don't support brace expansion. Added them to the blacklist so the fallback picks bash instead.

PR: #15610