Why Build Another Agent Harness

Sat, 04 Apr 2026 12:00:00 -0400

There are a lot of agent harnesses out there. So why build another one?

I've spent a lot of time in this space. I built several small agent systems in both Rust and Python, tried most of the popular frameworks, ran models from all the major providers and a bunch of open ones, experimented with custom LoRA layers and spec-driven task systems. Every setup taught me something about where things break down and I kept notes along the way.

What I wanted wasn't exotic. A system that runs on my hardware, manages agents as durable long-lived processes, connects to the communication channels I already use, and enforces real security boundaries between agents and data. Capability-based access control, taint tracking, domain isolation, per-process network filtering. These are all well-understood ideas with decades of prior art. The agent ecosystem just hasn't prioritized them yet because everyone's working on different problems.

Build Log on ./Sam_Stelfox.sh

Why Build Another Agent Harness