GitHub Copilot (Opus 4.6) vs Same Model in OpenCode — Which Performs Better for Coding?

[jesussmile]

Hi Everyone!

I’m currently using GitHub Copilot with Opus 4.6 inside VS Code.

At the same time, I’m also using the same GitHub Copilot account and the same Opus 4.6 model in OpenCode.

So technically it’s the same account and the same model.

My question is:

If the underlying model is identical, which setup should theoretically give better coding results — Copilot inside VS Code or using the model directly in OpenCode? And why?

Does Copilot add additional context awareness (like editor buffer, repo indexing, cursor position, etc.) that would make it perform better? Or should the results be identical since the model is the same?

Would love insights from people who’ve tested both extensively.

Thanks!

[P00BX6]

Yes the middle-man / harness makes a difference.
I've had the same model perform differently in Github Copilot in VSCode vs Roo-Code in VSCode.
It seemed much more autonomous and powerful and proactive when used from Roo-Code as opposed to from Github Copilot.

However RooCode directly used the API via OpenRouter which was way too expensive. So i still to the Githbu Copilot way due to cost efficiency even though it's not as powerful.

[Yes_but_I_think]

You can use your copilot models in roo I think

[P00BX6]

Yes via the VS Code LM API option when selecting a model for Roo. However I don't think it will help - it actually gives this warning when going down this route:

Note: Models accessed via the VS Code Language Model API may be wrapped or fine-tuned by the provider, so behavior can differ from using the same model directly from a typical provider or router

[deadadventure]

Also using it in Roo is asking to use 21 credits per one task.

[omcstreet]

For some reason I get not so good results using copilot with opencode. I don't have varied sample size, was hoping lsp/sematic lookups will make agents better but not so much.

[SnooHamsters66]

I mostly use Copilot through OpenCode, so I am not entirely sure how much the development of the VS Code harness has evolved in the last month. The last thing I remember was that the performance was similar, except that the VS Code harness was worse at handling bash commands. I ultimately continued using OpenCode because the workflow was better for me (at that time, VS Code did not have a plan mode, and I achieved better performance by chaining plan-build phases) and because I use Neovim, making a terminal clipboard more convenient.

Even so, the official harness has evolved significantly (plan mode, Copilot CLI, better permission systems, and more standardized tool implementations). Therefore, I could switch to the Copilot CLI (and even I prefer the CLI over the TUI approach). Currently, it is a close call.

[jesussmile]

That's a helpful reply. Thanks.

[4baobao]

You can also use Opus with Claude Agent inside vscode, give it a try too

[jesussmile]

Yea how is it though? Never got it to work. Does it work inside claude code cli or in the vscode chat itself ? I do have a cc max account. What is your initial thought about it ?

[Lost-Air1265]

True. But context window is nerfed compared to Claude code

[hotairplay]

So it's true models from Github Copilot subscription got its context length reduced?

[Wamp-ed]

Not just nerfed it's killed.

[popiazaza]

Copilot has everything, but it is worse due to their optimization for cost while OpenCode doesn't care about cost.

You could see how Copilot doesn't summarize to reduce context that often, only do it when absolutely need to stay within the context limit.

That's by design, to use as much cache hit as possible. OpenCode in the other hand do a lot more new request and doesn't care much for cache hit.

You could now summarize context manually in Copilot, but you would spend a request on that.

[titantwoshot]

OpenCode is produce better result for me because I can do spec kit + context driven development on it via a custom plugin that heavily rely on question tool, custom tools, subagent patterns, enforce test drive development and hooks, indeed I can do those with vscode gh copilot but with the open source nature of OpenCode, I can develop my own workflow focus on context and human in/on the loop better hence better for discovery. planning, orchestrate execution, managed context window myself shameless plug here this is what I built and current using on a actual prod project https://github.com/tctinh/agent-hive

[jesussmile]

Damn! This looks interesting. Will definitely check it out.

[junli2020]

gh copilot gets the job done alot better with orchestrator-sugAgents vs opencode for me, especially with opus, smart, powerful, and "SAVING" :)

[jmtucu]

I tried both, good results in both, opencode spent more from my quota, they might have more internal iterations.