How do I use openspec with opencode in plan mode

[Aditeya]

In OpenCode in Plan mode if i develop a spec, the agent won't be able to write it to file because there aren't any write permissions, I have to switch to build mode, but sometimes in build mode it just decides to implement it.

This just sucks so ideally I'd like some solution where plan mode only modifies spec, is there some solution to do this?

[TabishB]

@Aditeya I've found that this largely depends on the quality of model you use and how good it is with following instructions.

With Sonnet 4.5 it would always do this, but I've found that Opus 4.5 handles instructions a lot better.

You can also try using the new experimental workflow which might improve your experience too.

[Aditeya]

I did use opus 4.5 . The problem is plan mode in open code prevents writing files. I need a plan mode that allows writing but only to openspec? how would i go about doing that?

[Aditeya]

I found an opencode plugin that does exactly what I want. plan mode with openspec file writing support

https://github.com/Octane0411/opencode-plugin-openspec

[pbarvinko]

I had the same challenge. Also, I find the standard plan and build opencode agents somewhat limited.
So I ended up writing my own set of agents - architect, developer and code-reviewer - that work together in opencode to define the openspec specification and implement it. https://github.com/pbarvinko/opencode-openspec-multiagent

[cuteprince]

Hey @pbarvinko , I checked the set of agents you have implemented in you repo. Looks promising.
Just one question, in some of the agents (for example, code-reviewer.md, there is a reference to an @diff-summarizer agent).
However, I cannot see the .md file for diff-summarizer agent. Could you please update your repo to include this file as well ?

[clay-good]

Answered above — @Aditeya found opencode-plugin-openspec, which allows spec file writing in plan mode, and @pbarvinko shared a multi-agent alternative. Marked as the accepted answer.

Closing as answered — reopen if the plugin stops working for you.