# iii blog

Architecture posts and examples for coding agents. Read as markdown.

- [Blog home (HTML)](https://iii.dev/blog/)

- [Loop Engineering Is Just Software Engineering. We Have a Name for That.](https://iii.dev/blog/loop-engineering-is-just-software-engineering.md) — Loop engineering describes an event-driven, observable, stateful distributed system with retries, dead-letter handling, and durable state. The naming is different. The systems are the same. iii ships it as one worker.
- [How to Build Your Own Agent Harness](https://iii.dev/blog/how-to-build-your-own-agent-harness.md) — Most agent teams adopt a harness as one decision. iii decomposes it into eleven independently-replaceable workers on one engine bus. Build your own stops meaning fork a framework and starts meaning swap a few workers.
- [The Substrate Is Installable](https://iii.dev/blog/the-substrate-is-installable.md) — Every long-running agent ends up rebuilding the same surrounding layer: task state, event logs, replay, approvals, memory, retries, branching, provenance, capability tracking. The missing primitive is not missing. It is installed in three commands.
- [Why agent sandboxes are converging on libkrun, not Firecracker](https://iii.dev/blog/why-agent-sandboxes-are-converging-on-libkrun-not-firecracker.md) — Local-first coding agents need hardware isolation on macOS and Linux, and libkrun is the practical microVM path.
- [Building Agents for Real World](https://iii.dev/blog/building-agents-for-real-world.md) — Reliable agent systems converge when validation, isolation, and observability are properties of the runtime, not reminders in a playbook.
- [Add a worker](https://iii.dev/blog/add-a-worker.md) — The cloud is a bazaar, and that was okay until agents arrived and had to contend with 10,000 shops. Three primitives, one engine, and one answer to every question.
- [The Harness Is the Backend](https://iii.dev/blog/the-harness-is-the-backend.md) — The agent harness debate takes for granted that the harness is its own world, separate from the backend. iii makes a different bet: the harness is the backend.