Lilian Weng surveys harness engineering as the layer between a model and its task

Sources: primary, discussion
Summary: The post organizes coding-agent scaffolding into a progression of what is being optimized, from instruction prompts to structured context to workflow to harness code to optimizer code, and names a system at each step. It is dated 2026-07-04 on the author's site and resurfaced on Hacker News on 2026-08-04, so it is a survey rather than news.
Why it matters: It gives a vocabulary for the layer where a coding agent's behavior is set, which is the scaffolding around the model rather than the model.