In fact only the edit tool changed. That’s it.
0x0: The Wrong Question
The conversation right now is almost entirely about which model is best at coding, GPT-5.3 or Opus. Gemini vs whatever dropped this week. This framing is increasingly misleading because it treats the model as the only variable that matters, when in reality one of the bottlenecks is something much more mundane: the harness.
Not only is it where you capture the first impression of the user (is it uncontrollably scrolling, or smooth as butter?), it is also the source of every input token, and the interface between their output and every change made to your workspace.
I maintain a little “hobby harness”, oh-my-pi, a fork of Pi, a wonderful open-source coding agent by Mario Zechner. I’ve so far authored ~1,300 commits, mostly playing around and making incremental improvements here and there when I see a pain point, ( or autism strikes and I see an opportunity to embed more Rust via N-API because “spawning rg feels wrong” ).
Why bother, you ask? Opus may be a great model, but Claude Code to this day leaks raw JSONL from sub-agent outputs, wasting hundreds of thousands of tokens. I get to say, “fuck it, subagents output structured data now”.
Tool schemas, error messages, state management, everything between “the model knows what to change” and “the issue is resolved.” This is where most failures happen in practice.
Being model agnostic, it is a great testing ground, as the model is but a parameter. The real variable is the harness, where you have unimaginable control over.
Anyhow, let me tell you about this one variable I changed yesterday.
0x1: Edit Tool!
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