builder

builder is a skill for Claude Code from umangbuilds/dhurandhar-os. It costs 246 tokens per session (3,887 once invoked), scanned C, original, MIT.

A coding workflow that implements an approved specification using test-driven development, or TDD: writing a failing test before the code that makes it pass.

In plain words
What is it for?
Use it to implement specified features, functions, endpoints, or other changes while keeping tests and review part of the process.
Why use it?
It creates a repeatable path from requirements to tested code and adds a review step before the work is considered complete.

Skill for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_ROOT} variable. Also seen: mentions subagents; built for gstack.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the dhurandhar-os plugin — 10 skills, 1 hook shipped together

Good fit Use it to implement specified features, functions, endpoints, or other changes while keeping tests and review part of the process.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add umangbuilds/dhurandhar-os
Claude Code
/plugin install dhurandhar-os

Made for: Claude Code.

Or install dhurandhar-os, the plugin that ships this one along with the rest of its 10 skills, 1 hook.

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 builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/umangbuilds/dhurandhar-os/builder/github.svg)](https://agentmods.dev/skills/umangbuilds/dhurandhar-os/builder)
Your own site
<a href="https://agentmods.dev/skills/umangbuilds/dhurandhar-os/builder"><img src="https://agentmods.dev/badge/skills/umangbuilds/dhurandhar-os/builder/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 builder

Your own site · 80×15
<a href="https://agentmods.dev/skills/umangbuilds/dhurandhar-os/builder"><img src="https://agentmods.dev/badge/skills/umangbuilds/dhurandhar-os/builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 246 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,887 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. 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 $0.00246 $0.03887
Opus 5 $0.00123 $0.01944
Sonnet 5 $0.00049 $0.00777
Haiku 4.5 $0.00025 $0.00389

Measured 10d ago against content hash 621f60066854, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade C, and why

builder scanned grade C with 1 finding 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 10d 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.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

- `rm -rf` (anywhere outside `.tmp/`, `node_modules/`, `__pycache__/`, build artifacts).
skills/builder/SKILL.md · 273 lines

How it starts

The opening of the file, as written. The whole thing — 273 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Builder

Builder is the TDD-first implementation orchestrator. The operator says "build the disbursement webhook" — Builder writes the plan first, the failing test second, the implementation third, and hands off to Reviewer fourth.

The discipline is the moat. Builder enforces it.


When this skill activates

Builder owns spec-to-code, not raw build intent. The split with workflow-orchestrator:

  • Raw build intent ("I want to build X", "let's build Y", "create a tool that Z", "I have an idea for Q") → workflow-orchestrator fires first, walks the operator through reality-check → PRD → build → review → launch, and only then hands off to Builder.
  • Spec-to-code ("implement the spec," "build per the PRD," "code this up based on the spec," "let's code," "write the function for X in the spec," "ship the spec," "implement Y from the PRD") → Builder fires directly.

Auto-trigger conditions:

  • Spec-aware phrases: "implement the spec," "build per the PRD," "code this up," "code this up based on the spec," "let's code," "ship the spec," "write the function for [X in the spec]," "implement [Y from the PRD]."
  • Concrete implementation phrases when a PRD or locked spec exists in the working directory or session: "write the function," "create the endpoint," "make a CLI for," "wire up the integration."
  • Any edit operation targeting a path containing .env, prod.config, or production.
  • Direct invocation by workflow-orchestrator after the PRD checkpoint (build).

Explicit invocation: "use builder to implement X."

Does NOT activate on:

  • Raw build intent without a spec (workflow-orchestrator owns this — see its triggers).
  • Spec writing (PRD Writer), code review (Reviewer), brainstorming (Idea Reality Check), deployment architecture (Deployment Advisor).

Spec presence check. Before responding to an ambiguous "build X" / "let's code" message, look for a PRD signal: a file named prd.md / spec.md / PRD.md / SPEC.md / *.prd.md in the working directory, OR a spec produced earlier in this session, OR an explicit operator reference to a prior spec ("the PRD we wrote yesterday"). If a spec signal is present, Builder fires. If not, yield to workflow-orchestrator.

Read the full file on GitHub · 273 lines

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. 10d ago First seen · 273 lines · 246 tokens per session scan C 621f60066854

Subscribe to this mod's changes

builder is a skill published in the GitHub repository umangbuilds/dhurandhar-os (1 stars, last pushed 4mo ago), licensed MIT. It adds 246 tokens to every session and 3,887 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.