sdlc-tdd

sdlc-tdd is a skill for Claude Code, Codex from djscheuf/agentic-dev-ecosystem-template. It costs 41 tokens per session (416 once invoked), scanned A, original, MIT.

A single test-driven development cycle for implementing one test at a time. It writes a failing test, adds the smallest code that passes it, and commits that cycle's changes.

In plain words
What is it for?
Use it when an implementation plan and test cases already exist. It handles the Red phase, the Green phase, verification, and a separate commit for each completed test.
Why use it?
It breaks feature work into small, verifiable steps so each change is checked before the next one begins.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/djscheuf/agentic-dev-ecosystem-template/sdlc-tdd
Any agent
npx skills add djscheuf/agentic-dev-ecosystem-template --skill sdlc-tdd
Clone the repo
git clone --depth 1 https://github.com/djscheuf/agentic-dev-ecosystem-template

Made for: Claude Code, Codex.

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 sdlc-tdd

README.md
[![agentmods](https://agentmods.dev/badge/skills/djscheuf/agentic-dev-ecosystem-template/sdlc-tdd.svg)](https://agentmods.dev/skills/djscheuf/agentic-dev-ecosystem-template/sdlc-tdd)
Your own site
<a href="https://agentmods.dev/skills/djscheuf/agentic-dev-ecosystem-template/sdlc-tdd"><img src="https://agentmods.dev/badge/skills/djscheuf/agentic-dev-ecosystem-template/sdlc-tdd.svg" alt="Measured on agentmods" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 416 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00041 $0.00416
Opus 5 $0.00020 $0.00208
Sonnet 5 $0.00008 $0.00083
Haiku 4.5 $0.00004 $0.00042

Measured 5d ago against content hash 530ed1f4f16c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sdlc-tdd 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 5d 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.

.devin/skills/sdlc-tdd/SKILL.md · 51 lines

What it actually says

SDLC TDD Sub-Workflow

Purpose

Implement one test from a Test plan.

Trigger

  • After designing Test Cases, and for a Single Test.

Inputs Required

  • Design of the user story
  • Implementation plan
  • Relevant domain context
  • Test Cases Document

Overview

This workflow orchestrates the core TDD Red-Green Loop in a continuous cycle until the feature is complete.

TDD Implementation Cycle

  1. Red - Write a failing test (INVOKE write-failing-test skill)
  2. Green - Write minimal passing code (INVOKE write-minimal-implementation skill)
  3. PAUSE & COMMIT: git commit ONLY YOUR CHANGES with message "feat: [description] - test [N] of [total]"
  4. More Tests in Priority Group?
    • If yes, go back to 1.
    • If no, finish workflow.

Workflow Chain

CRITICAL: One Test at a Time Run the cycle ONCE For EACH test in the priority group. CRITICAL - Write Sentinel Files when instructed.

Phase 1 - Red Phase

  • INVOKE write-failing-test skill (mandatory - do not skip)
  • Address any verification failures before proceeding

Phase 2 - Green Phase

  • INVOKE write-minimal-implementation skill (mandatory - do not skip)
  • Address any verification failures before proceeding

Phase 3 - Commit Phase

  • git commit ONLY YOUR CHANGES with message: "feat: [description] - test [N] of [total]"

Phase 4 - Loop Decision

  • If More test in Priority Group, go back to Phase 1
  • If no more tests in Priority Group, finish workflow
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. 5d ago First seen · 51 lines · 41 tokens per session scan A 530ed1f4f16c

Subscribe to this mod's changes

sdlc-tdd is a skill published in the GitHub repository djscheuf/agentic-dev-ecosystem-template (12 stars, last pushed today), licensed MIT. It adds 41 tokens to every session and 416 once invoked, about $0.0002 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.