harness-audit

Audit the four rings

Theory: The four rings and Harness practice. Build from the outside in: containment, guides, sensors, permissions. The order matters because each ring must hold when every ring inside it fails — a guide can be ignored, a sensor can miss, an approval can be misclicked; a wall does not care.

Core rule

Report and rank; never harden anything yourself. The audit's one organising question is the blast radius: describe the worst session possible under the current setup and what it costs. If the user asks you to apply fixes afterwards, that is a normal edit session, not this skill.

Workflow

1. Ring one — containment: what can it physically reach? Where does the agent run: the user's checkout or a worktree/container? Which credentials are in its environment — a read-only database user or the application's? Open internet or an allowlist? Real API keys or test keys? The finding is one sentence: "the worst session deletes X and spends Y."
2. Ring two — guides: what does it read before acting? Find CLAUDE.md / AGENTS.md and tool descriptions. Every line should be a rule the agent can act on — flag philosophy, history, and anything over roughly a page. Flag missing rules for the repo's real landmines (migrations, generated files, deploy scripts).
3. Ring three — sensors: what fires when it errs? Is there one command (make check or equivalent) that runs tests, linter and types? Does the harness run it automatically after edits — a hook — or does correctness depend on the model remembering? A sensor the model must invoke voluntarily is a guide, not a sensor.
4. Ring four — permissions: what still needs a human? List what is auto-approved. The irreversible set — push to main, deploy, spend, delete data, send messages — should need a person; everything reversible inside the walls should not. Flag both failure modes: irreversible actions auto-approved, and reversible ones prompting so often the user rubber-stamps (approval fatigue is a hole in this ring, not a virtue).
5. Check the order. The classic smell is an inner ring doing an outer ring's job: a prompt line saying "never touch prod" where a credential should have been removed. Rules in guides that could be walls belong in ring one.

Output format

Harness audit — <project>
blast radius: <the worst session in one sentence>

ring 1 containment  <held | open>  <finding>
ring 2 guides       <held | open>  <finding>
ring 3 sensors      <held | open>  <finding>
ring 4 permissions  <held | open>  <finding>

Hardening list, outermost first:
1. ...

Rank fixes outside-in — a wall before a better prompt, a sensor before a politer rule. Close by restating the blast radius as it would be after fix 1 alone.