Claude Code Build Loop Agent Skill

Use when building features with Claude Code in any codebase and the work should go through a disciplined build → review → test → fix…

Context cost
875 tokensestimated from the bundle, loaded when it triggers
Bundle
1 file · 3.5 kBtext throughout, nothing executable
Licence
MITthe author’s own terms
Last change
—v1.0
Servers it uses
Noneruns standalone

What it does

Use when building features with **Claude Code** in any codebase and the work should go through a disciplined build → review → test → fix loop. Triggers on "run the build loop", "build the next task", "continue the plan", "build this feature properly", or any request to implement work from a plan file or a direct feature prompt. Builds from the plan (or the prompt if no plan exists), runs Claude Code's `/review` (plus `/security-review` for sensitive surfaces) and fixes every issue found, tests and verifies the feature end to end, fixes anything testing surfaces, and reports back once…

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

productivity

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md3.5 kB · preview
--- name: build-loop-claude-code license: MIT metadata: author: BuilderOS version: "1.0" ---
10# Claude Code Build Loop
11
12Quality-gated feature work: nothing ships on "it compiles" — every increment is built, reviewed, tested end to end, and fixed before the user hears "done."
13
14## Source of work
15
16- **A plan file exists** (roadmap, refactor plan, or task list with - [ ] checkboxes — search the repo): work the first unchecked task. Tasks are ordered intentionally — never skip ahead. If the plan references spec docs, read only the sections relevant to the current task.
17- **No plan (or the request is outside it):** build from the user's prompt. Restate it as a verifiable goal with 2–4 success criteria and confirm scope in one message before building.
18
19## The loop
20
21Run per task (or per prompted feature). Do not advance until every step passes.
22
231. **Build.** Implement exactly what the task specifies. Simplest implementation that satisfies it, surgical changes, no speculative scope. Match existing project conventions.
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252. **Review.** Run **/review** on the changed code. If the change touches auth, payments, user input, or data access, also run **/security-review**. Fix all findings in scope — bugs, security issues, edge cases, performance, style in files you touched. If the project has a design system spec (design tokens file, DESIGN.md, theme config), check UI changes against it — no hardcoded colors, type, or spacing that bypass tokens. Note pre-existing issues in untouched code for the report instead of fixing silently. Re-run /review until clean. If a finding contradicts the task or spec, the spec wins — flag the disagreement.
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273. **Test end to end.** Run the task's verification step (or the success criteria). Run the full test suite — everything that passed before must still pass. Add tests for new logic. Then exercise the feature as a user would: run the app, walk the real flow including empty, loading, and error states.
28
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md568 words
Files1
LicenceMIT
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈190
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
685
on trigger
The instruction body, read only when the skill fires.
0.44%
of a 200k window
Ten skills this size would take about 4% of the window before you open a file.
050k100k150k200k context window

875 tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Small enough to keep loaded permanently without thinking about it.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

1 file, 3.5 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md3.5 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 1 file you can review in full before installing. The MIT licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Claude Code Build Loop · 875 tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/claude-code-build-loop/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/claude-code-build-loop" ] && { [ ! -e .claude/skills/claude-code-build-loop ] || { mv .claude/skills/claude-code-build-loop "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/claude-code-build-loop" .claude/skills/ && echo "Installed .claude/skills/claude-code-build-loop"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add lucasmaher-hash/claude-code-build-loop

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/claude-code-build-loop/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/claude-code-build-loop/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/claude-code-build-loop" ] && { [ ! -e ~/.claude/skills/claude-code-build-loop ] || { mv ~/.claude/skills/claude-code-build-loop "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/claude-code-build-loop" ~/.claude/skills/ && echo "Installed ~/.claude/skills/claude-code-build-loop" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/claude-code-build-loop/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as build-loop-claude-code in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, claude-code-build-loop.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Version1.0
Publishedno release date on file
PriceFree
Referencelucasmaher-hash/claude-code-build-loop

Versions

v1.0 is what is on the shelf; no release here carries a date. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

v1.0
  • No earlier releases have been published to the marketplace.
Pinning

The install command always fetches the release that is current the day you run it — v1.0 today — and cannot ask for an earlier one. The copy on your disk does not change until you run it again.

Reviews

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