I like this tutorial for an agent in 50 lines:

http://minimal-agent.com/

And if you add one additional while loop, for user input, you can actually use it! :)

https://gist.github.com/a-n-d-a-i/5461a662ef8a7ee0a5eb7778c8...

Build it from scratch. Understanding fundamentals of how agentic coding harnesses is a must though if you gonna go that route. I think everyone should take time and learn these things, maybe reverse engineer Codex Cli or something like that as a starter. That info is very valuable in this day and age.

Not the comment author, but I use pi and customize it with my own extensions. Pi automatically tells models how to customize itself, so it's a pretty easy process.

I started mine from scratch in 2023 because I wanted to use LLMs from a terminal and there was nothing else compelling at the time (nowadays there is pi and opencode)

Harnesses are/can be incredibly simple things, not much more than a HTTP client that renders things in a way that suites your taste.

It’s not that difficult, it’s just a system prompt and a set of basic file edit/bash/etc tools.

Me, personally, I didn’t build it from scratch but I ported original CC from published sources into Python and extended it to match my own requirements.

Here is a video I made explaining it from absolute basics:

https://m.youtube.com/watch?v=_AgKuFGvJfI

And the repo:

https://github.com/abtinf/homunctor

Building something like this is the todo list of agents.

I found this one easy to understand:

https://ampcode.com/notes/how-to-build-an-agent

The real question is when do you transition from building it with codex/CC to the harness itself.

Lots of ways, it's a good exercise that you will learn a lot doing. Might make you cynical w.r.t. big ai harnesses

I used ADK, Dagger, and a VS Code extension for mine. Currently using opencode though.

Why use a personal harness?

You have to pay API pricing, which is far more costly.

I'd either switch to GLM wholesale or just continue to use Opus within Claude Code as the blessed, subsidized path.

Which is why my vibeslop harness supports `claude -p` as one of its backends.

I self-host DeepSeek V4 Flash on 2 DGX Sparks (approx. $10k)

I expect DeepSeek V4 Flash (or an equivalently sized model) to reach parity with GLM 5.2 some time this year (this based on DeepSeek V4 Flash launching at GLM 5.0 parity[0], and GLM 5.2 being freely available to distill from)

GLM 5.2 is within spitting distance of Opus 4.8 and is at least as good as Opus 4.6[1] which some devs were willing to spend hundreds to single-digit thousands of dollars a month for a few months ago.

[0]: https://artificialanalysis.ai/models/comparisons/deepseek-v4...

[1]: https://artificialanalysis.ai/models/comparisons/claude-opus...

It did not write it for me, I used it to add a feature I wanted. It's a pretty small and understandable codebase, in fact :)

Does anyone know what’s gone wrong with Anthropic?

They used to be a decently credible company with not-too-shady behaviour...

I hope they can actually regain some credibility…

Phased rollouts are a triggering microagression for some.