build-fast

build-fast is a skill for Claude Code from rp1-run/rp1. It costs 20 tokens per session (3,117 once invoked), scanned A, original, Apache-2.0.

A short development workflow for focused changes, using three stages: plan, build, and an optional review.

In plain words
What is it for?
It helps plan a targeted change, implement it, and optionally review and finalize the result.
Why use it?
It provides a lightweight path for small or medium changes while preserving planning and implementation records.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions subagents.

Part of the rp1-dev plugin — 23 skills, 36 agents shipped together

Good fit It helps plan a targeted change, implement it, and optionally review and finalize the result.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/rp1-run/rp1/build-fast
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 rp1-run/rp1 --skill build-fast
Clone the repo
git clone --depth 1 https://github.com/rp1-run/rp1

Made for: Claude Code.

Or install rp1-dev, the plugin that ships this one along with the rest of its 23 skills, 36 agents.

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-fast

README.md
[![agentmods](https://agentmods.dev/badge/skills/rp1-run/rp1/build-fast/github.svg)](https://agentmods.dev/skills/rp1-run/rp1/build-fast)
Your own site
<a href="https://agentmods.dev/skills/rp1-run/rp1/build-fast"><img src="https://agentmods.dev/badge/skills/rp1-run/rp1/build-fast/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-fast

Your own site · 80×15
<a href="https://agentmods.dev/skills/rp1-run/rp1/build-fast"><img src="https://agentmods.dev/badge/skills/rp1-run/rp1/build-fast.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,117 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.
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 $0.00020 $0.03117
Opus 5.5 $0.00008 $0.01247
Sonnet 5.5 $0.00004 $0.00623
Haiku 4.5 $0.00002 $0.00312

Measured 1mo ago against content hash 9116249e45d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

build-fast 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 1mo 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.

plugins/dev/skills/build-fast/SKILL.md · 321 lines

How it starts

The opening of the file, as written. The whole thing — 321 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Build Fast Command

Quick-iteration workflow for focused changes. Three-phase execution: plan -> build -> [review].

§CTX

Use the pre-resolved projectRoot, kbRoot, workRoot, and codeRoot values from the generated Workflow Bootstrap section. Do not hardcode .rp1/work/ or .rp1/context/ paths.

References

File Purpose When to Load
references/review-and-finalization.md Optional review pass, cleanup manifest, comment cleanup, push, post-implementation checkpoint Once the build phase completes

§VERSION-GATE

If RP1_VERSION < 0.3.3 then STOP execution with message:

Your rp1 CLI needs to be updated.

Please run `/rp1-base:self-update` to update, then retry this command.

Or in the terminal: `rp1 update`

§FLAG-LOGIC

When AFK=true, treat CONFIRM_PLAN as false regardless of the value passed. AFK means zero user interaction, so every user prompt in this workflow is skipped — an AFK run that pauses for input has nobody to answer it.

When AFK=false, the plan review checkpoint is mandatory after planner artifact registration and before §PHASE-2. CONFIRM_PLAN does not control the plan checkpoint; it only enables the post-implementation checkpoint in §4.4.

Effective values when AFK=true:

  • Plan review checkpoint -> SKIP
  • CONFIRM_PLAN -> false (forced, disables post-implementation checkpoint)
  • All checkpoints -> SKIP (no user prompts)

STATE-MACHINE

stateDiagram-v2
    [*] --> plan
    plan --> build : plan_ready
    build --> review : build_complete
    review --> [*] : done

On each phase transition, report via:

rp1 agent-tools emit \
  --workflow build-fast \
  --type status_change \
  --run-id {RUN_ID} \
  --name "{RUN_NAME}" \
  --step {CURRENT_STATE} \
  --data '{"status": "running"}'
  • RUN_ID comes from the generated Workflow Bootstrap section
  • Derive RUN_NAME from the development request: a brief summary (max 60 chars) prefixed with "Feature: " (e.g., "Feature: Add logout button to navbar")

Read the full file on GitHub · 321 lines

Files

What ships with it

1 file 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. 1mo ago First seen · 321 lines · 20 tokens per session scan A 9116249e45d9

Subscribe to this mod's changes

build-fast is a skill published in the GitHub repository rp1-run/rp1 (38 stars, last pushed today), licensed Apache-2.0. It adds 20 tokens to every session and 3,117 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-07.

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