Gauntlet Loop — core skill (domain-agnostic)

A disciplined loop for producing high-quality work in any domain: build → blind critique → revise → repeat, against a bar the agent cannot talk its way past. Coding, writing, design, data, research, prompt engineering and detection all use the same loop — they differ only in how you pick the bar, what the critic inspects, and the checklist. Those live in references/domains/.

Origin: the Gauntlet Loop method is Matt Shumer's, from "How to Run a Gauntlet Loop" (https://somethingbig.ai/gauntlet-loop), with the companion repo mshumer/Claude-of-Duty. This skill is an independent, attributed adaptation — see ../../CREDITS.md.

Prerequisite: a real agent harness

This loop requires an agentic harness that can open files, run code, render output, take screenshots, call tools, and spawn sub-agents with their own clean context (Claude Code, Cowork, Codex, or equivalent). A single-turn chat cannot produce an independent blind critic — if you can only reply in one context, say so and fall back to a single self-review pass instead of pretending the loop ran.

For large multi-agent runs, use the harness's parallel-agent facilities (in Claude Code: sub-agents, or /ultracode when available).

The four pillars

1. A bar the agent cannot argue around. The strongest form: the artifact must match or beat something real — a reference implementation, a test suite, a top product's screenshot, a model essay, an eval set, an ATT&CK technique, a working PoC. The bar may be aspirational: it does not have to be realistically reachable. An unreachable bar keeps the loop pulling upward instead of stopping at "good enough".
2. Give the goal, not the implementation. State what the finished thing must achieve; let the agent choose the route. Prescribing architecture replaces the model's judgment with yours and caps the result at your imagination.
3. Let the agent split the work. The lead breaks the goal into the smallest pieces that can be improved and graded independently. Independent pieces can run as parallel loops.
4. The builder never grades itself. The builder and the judge are different agents with separate context. The critic is blind to the builder's reasoning and inspects the real artifact — running code, rendered pixels, actual test output — never the builder's summary.

First step when this skill loads

1. Identify the work type.
2. Read the matching domain file for how to choose the bar, what the critic must inspect, and a worked example:

- Code / refactor / library / feature → references/domains/coding.md - Essays, docs, messaging, marketing copy → references/domains/writing.md - UI / visual / landing pages → references/domains/design.md - Analytics, metrics, modeling → references/domains/data-analysis.md - Literature / market / competitive research → references/domains/research.md - Prompts, agents, skills, LLM features → references/domains/prompt-eval.md - SIEM/EDR detection rules (blue team) → references/domains/detection.md - Anything else → the generic frame below plus references/choosing-the-bar.md

1. Read references/running-the-loop.md for orchestration mechanics: budget, parallelism, the progress workbench, and the final smoothing pass.
2. Run LEAD → BUILDER → CRITIC as described.

Hunting security vulnerabilities is a special case with different triggers and mandatory safety rules → use the separate security-vuln-gauntlet skill.

The three roles (never share context)

• LEAD (orchestrator). Sets the bar and the loop budget, splits the goal into gradeable units, routes FAILs back, merges results. Does not build — an agent that built something is a biased judge of it.
• BUILDER (specialist, clean context). Builds one part for real and produces an artifact. Allowed to be imperfect. Never declares PASS.
• CRITIC (blind, separate clean context). Never sees the builder's reasoning. Inspects the artifact against the bar, demands objective evidence, and passes only when the bar is met. See references/critic-design.md.

The loop

1. Set the bar and the budget. Concrete, measurable, ideally beat this specific real thing. If no reference is obvious, the first job is: "find a concrete comparison or measurement" — do not start building against a vague target. See references/choosing-the-bar.md.
2. Split (LEAD). List the smallest units worth grading separately (by component, by flow, by quality dimension). Independent units → parallel loops.
3. Build (BUILDER × N, parallel, clean contexts). Each builder produces a real artifact.
4. Critique (CRITIC, blind). The critic inspects the real thing, grades each bar criterion with evidence, and returns PASS/FAIL plus specific fixes. Blind A/B against the reference whenever the domain allows.
5. Fix and repeat. Feed FAILs back with the critic's reasons. Run longer than feels necessary — most people stop several rounds too early. Split hard parts further; try variants.
6. Smooth (optional but recommended). One fresh agent inspects the whole assembled result and fixes inconsistencies between separately-improved pieces. It harmonizes; it does not redesign.
7. Report. Final artifact + the bar used + a round log + PASS evidence + anything still under the bar.

Stopping

The bar may be unreachable by design, so "bar met" is not the only stop condition. Stop when any of these holds:

• every unit clears the bar; or
• two consecutive rounds produce no improvement against the bar; or
• the loop budget (rounds, time, tokens) is exhausted.

Always record what is still below the bar. If the work is still visibly improving and budget remains, keep going.

Monitoring without interrupting

Long runs are worth watching, but stopping to ask for status costs a round. Have the loop maintain a live progress workbench — a workbench.md or a self-refreshing HTML page — updated after each round with: current round, per-unit PASS/FAIL, the critic's evidence, and links to the latest artifacts/screenshots. Read it asynchronously; intervene only when the loop is stuck on the wrong thing.

Why this beats one-shot work

When NOT to use this

The loop costs many times the tokens and wall-clock of a single pass. Skip it for small, low-stakes, one-off work (quick answers, throwaway scripts, a one-line fix). Use it when quality genuinely matters and you can name something real to be measured against.

Expected output

Final artifact that clears (or best-approaches) the bar, plus: the bar definition, a round log (what FAILed → what changed), objective PASS evidence (test results, blind A/B outcome, recomputation, screenshots, PoC), and remaining gaps.

References

• references/methodology.md — the full method and its rationale.
• references/running-the-loop.md — orchestration: budget, parallelism, workbench, smoothing pass.
• references/prompt-templates.md — LEAD / BUILDER / CRITIC / SMOOTHER prompts + meta-prompt.
• references/choosing-the-bar.md — how to pick a bar per kind of work.
• references/critic-design.md — designing a blind critic that inspects reality.
• references/domains/coding.md — software (reference implementation / test-as-bar).
• references/domains/writing.md — writing (model text, blind A/B).
• references/domains/design.md — UI/visual (blind A/B against top products).
• references/domains/data-analysis.md — analysis (correct + robust + reproducible).
• references/domains/research.md — research (source-verified, no fabricated citations).
• references/domains/prompt-eval.md — prompts/agents/skills (eval-as-bar, head-to-head).
• references/domains/detection.md — detection engineering (ATT&CK + zero false positives).