build-loop

build-loop is a skill for Claude Code from nelsonwerd/idea-to-ship-skills. It costs 206 tokens per session (4,713 once invoked), scanned A, original, MIT.

A repeatable build-and-test process that takes a project from compiling to meeting its acceptance criteria. It uses existing tools to build, inspect, exercise, check, critique, and rebuild.

In plain words
What is it for?
Use it to run builds and tests, inspect screenshots, exercise flows with Playwright, check accessibility or performance, record what was tested, and stop when criteria pass or a defined stop condition is reached.
Why use it?
It addresses the gap between code that appears finished and a product that actually works in tested use.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the idea-to-ship-skills plugin — 6 skills shipped together

Good fit Use it to run builds and tests, inspect screenshots, exercise flows with Playwright, check accessibility or performance, record what was tested, and stop when criteria pass or a defined stop condition is reached.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nelsonwerd/idea-to-ship-skills/build-loop
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add nelsonwerd/idea-to-ship-skills --skill build-loop
Clone the repo
git clone --depth 1 https://github.com/nelsonwerd/idea-to-ship-skills

Made for: Claude Code.

Or install idea-to-ship-skills, the plugin that ships this one along with the rest of its 6 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for build-loop

README.md
[![agentmods](https://agentmods.dev/badge/skills/nelsonwerd/idea-to-ship-skills/build-loop/github.svg)](https://agentmods.dev/skills/nelsonwerd/idea-to-ship-skills/build-loop)
Your own site
<a href="https://agentmods.dev/skills/nelsonwerd/idea-to-ship-skills/build-loop"><img src="https://agentmods.dev/badge/skills/nelsonwerd/idea-to-ship-skills/build-loop/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for build-loop

Your own site · 80×15
<a href="https://agentmods.dev/skills/nelsonwerd/idea-to-ship-skills/build-loop"><img src="https://agentmods.dev/badge/skills/nelsonwerd/idea-to-ship-skills/build-loop.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 206 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,713 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 28
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00206 $0.04713
Opus 5 $0.00103 $0.02357
Sonnet 5 $0.00041 $0.00943
Haiku 4.5 $0.00021 $0.00471

Measured 9d ago against content hash 925ad760ffdf, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

build-loop scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/build-loop/SKILL.md · 157 lines

How it starts

The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Build-Loop — see-and-exercise iteration until a build actually works

build-loop takes a build that compiles-but-isn't-done and drives it toward near-finish-line craft by repeating one disciplined cycle — build → see → exercise → check → critique → rebuild — until its acceptance criteria pass or a stop-condition fires. It doesn't just re-read its own plan; it runs, sees, and exercises what it built, then feeds those observations back into the next rebuild.

It is composition-first: it orchestrates tools the agent already has — bash (build/test), a headless screenshot + vision to see, Playwright/headless to exercise the flows, axe/Lighthouse to check — via prose. It is not a new program, and not a reinvention of the see-and-exercise agents vendors already ship; it's the discipline that wraps them: a target, a loop, a stop-condition, and an honest ledger of what was actually checked.

This skill is the downstream partner to prompt-pack (which sequences what to build) and ideate (which decides whether to build it). It carries prompt-pack's execute-discipline (never fake a signal you didn't run) and ideate's conditional-design (a design bar only when feel is load-bearing).

When to use this

Strong triggers — invoke without asking:

  • "Tighten this build" / "drive it to near-finish-line" / "make it actually work, not just compile"
  • "Iterate until it passes" / "loop until the core flows pass"
  • "Self-verify the UI" / "see whether what I built actually renders and works"

Softer triggers — invoke proactively:

  • A scaffold or feature just landed and you want it driven from "compiles" to "works + holds a craft bar."
  • You're about to hand a draft to a human and want the machine-checkable defects gone first.

Do NOT use this for:

  • Deciding what to build or whether it's worth building → that's ideate.
  • Judging whether a design/strategy/codebase is sound or safe → that's deep-dive.
  • A one-line fix you can make and eyeball in ten seconds → just do it.
  • Validating that people want it → out of scope (see bounds below); that's the human/market handoff.

Read the full file on GitHub · 157 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 157 lines · 206 tokens per session scan A 925ad760ffdf

Subscribe to this mod's changes

build-loop is a skill published in the GitHub repository nelsonwerd/idea-to-ship-skills (83 stars, last pushed 1mo ago), licensed MIT. It adds 206 tokens to every session and 4,713 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories