Open-source series breaks down the full harness behind production coding agents
blaizedsouza · x · 2026-07-21
- The author is turning a multi-lesson series into an open-source build of a production-grade coding agent from scratch in Python. - The focus is not just the LLM loop, but the surrounding harness: context engineering, human-in-the-loop workflows, durable execution, permissions and sandboxes, skills and subagents, plus evals and observability. - The stack mentioned includes Modal for hosting open-source LLMs such as Qwen3, Kitaru for durable runtime so agents can pause and resume, and Opik for evaluation/observability. - The diagram breaks the system into interactive vs. remote interfaces, a headless harness, a context window, an agent loop, and supporting modules like memory, skills, sandbox, permissions, and an LSP server.
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