coding-agents
9 essays on this topic.
- The Harness Is Part of the Token Bill
The same model family solved every hidden-test repair through Pi and Grok Build, but one route reported sixteen times the total tokens. Most of the gap was context, not answers.
- The Half of DeepSeek Harness Nobody Is Reading
The runtime got the reviews. The transferable part is how a 2,500-pull-request, agent-written repository keeps itself honest, and one of its rules caught a stale instruction in my own setup the same afternoon.
- What A Prompt Trim Cannot See
Deleting your agent's accumulated instructions is safest for the people who never tested them, and most dangerous for the people who did.
- Where the Harness Starts to Matter
In April my benchmark said coding correctness is model-determined and the harness is a thin proxy. Two newer results show exactly where that claim breaks: the harness matters at the edge of what the model can do.
- Assume the LLM never ran
A 208 MB log, 59,356 retries, and zero LLM calls. A debugging story about what happens when the symptom lies about the cause.
- Test-first dispatch for AI coding agents
The architect writes the tests. The implementer makes them pass. No prose specs, no circular validation.
- I made my coding agent dispatch system improve itself
I dispatched a 952-line monolithic CLI through my own coding-agent dispatch system to be refactored into seven modules. It worked. Notes on what self-bootstrap reveals about agent harness design.
- What 16,000 Simon Willison posts reveal about the state of AI coding agents
I scraped 16,181 of Simon Willison's posts and analysed the 395 from 2026. An inflection in November 2025, GLM-5 closing the gap, and why the harness — not the model — is the competitive moat.
- Correctness is model-determined
I benchmarked four AI coding harnesses on 12 tasks using the same model. The harness barely matters for correctness — it's all about the model.