HarnessTrim

This skill should be used when deciding whether to hand volumetric or noisy work to an isolated subagent (or another harness) instead of doing it in the main context — e.g. reading many files, digesting long logs/docs, wide searches, or bulk mechanical generation. It gives the rule for when isolation saves tokens versus when it just multiplies them. Part of the HarnessTrim token-economy stack.

This skill should be used for mechanical, low-novelty coding work — generating boilerplate, wiring up a component from an existing pattern, adding a CRUD endpoint like the others, writing repetitive tests, or applying a rote transformation across files. It keeps reasoning effort low and output terse for work whose shape is already decided. Part of the HarnessTrim token-economy stack; the lean-scaffold preset pairs it with low reasoning effort.

This skill should be used when a session is being compacted/summarized (context is full or the user runs a compact command), or when writing any handoff summary that a later session or subagent will continue from. Defines what to preserve versus drop so the continuation doesn't waste tokens re-reading files and re-deriving state. Part of the HarnessTrim token-economy stack; the OpenCode adapter injects this guidance automatically via experimental.session.compacting.

This skill should be used before pasting, printing, or otherwise embedding test-runner output, build logs, or CI output into the conversation — whenever a test suite, linter, or build was just run and its raw output is large. Filters logs down to failure/error signal before they enter context. Part of the HarnessTrim token-economy stack (see packages/core/src/reducers/test-output-slim.ts for the reference implementation the OpenCode adapter automates this with).

This skill should be used for every response produced in a coding harness (Claude Code, Codex, OpenCode, Pi) — not only when explicitly requested. Enforces terse, structured, information-dense output instead of narrated verbosity, to cut output-token cost. Part of the HarnessTrim token-economy stack (see delta-response/references/examples.md for before/after samples).

This skill should be used when asked to review code, review a pull request, or review a diff. Focuses the review on problems worth fixing rather than restating or summarizing what changed. Part of the HarnessTrim token-economy stack.