Skill Issue: Harness Engineering for Coding Agents

Skills, MCP servers, sub-agents, hooks, and back-pressure mechanisms are tactical solutions HumanLayer has arrived at.

Case-study framing of harness engineering for coding agents, with specific claims about what does and does not work (notably: role-based sub-agents don't work; sub-agents for context control do).

A strong counter-example to thin-harness-in-the-limit. HumanLayer has shipped coding-agent product and reports that sub-agents, hooks, and back-pressure do real work. Sharpens the disagreement with Tan/Miessler and localises it.

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HumanLayer's post is the library's best current counterweight to the thin-harness pole. The claim is not that more harness is always better — they explicitly report that role-based sub-agents ("frontend engineer," "backend engineer") don't work. The claim is that specific harness moves — sub-agents as context-control, hooks, back-pressure — carry real load and cannot be absorbed into a better model. The piece is useful for the library because it: • Distinguishes harness types that work from those that don't, empirically rather than in principle. • Names specific mechanisms (sub-agents-for-context, back-pressure) that belong on the harness_types taxonomy. • Speaks from shipped product, which raises its weight on the practitioner-note vs framework-piece axis. Read alongside • Tan, "Thin Harness, Fat Skills" — the opposite pole. • Miessler, "Good and Bad Harness Engineering" — the pole this piece is most compatible with. • Anthropic, "Agent Skills" — the vendor framing for one of the tactical solutions cited.

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