An implementation workflow for writing production code, adding features, refactoring, and tests. TDD, or test-driven development, is the practice of writing a failing test before the code that makes it pass.

Use it when creating functions, endpoints, routes, components, tests, or other production changes.

It provides a defined path for implementation and can use TDD when requested or enabled in project settings. Without that setting, it uses direct implementation by default.

cf-tdd — Skill for Claude Code by dinhanhthi

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/dinhanhthi/coding-friend

agentmods

npx agentmods add skills/dinhanhthi/coding-friend/cf-tdd

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/dinhanhthi/coding-friend/cf-tdd.svg)](https://agentmods.dev/skills/dinhanhthi/coding-friend/cf-tdd)

Your own site

<a href="https://agentmods.dev/skills/dinhanhthi/coding-friend/cf-tdd"><img src="https://agentmods.dev/badge/skills/dinhanhthi/coding-friend/cf-tdd.svg" alt="Measured on agentmods" height="20"></a>

Per session 136 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,869 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.

Model	Per session	Once invoked
Fable 5.1	$0.00136	$0.01869
Opus 5	$0.00068	$0.00934
Sonnet 5	$0.00027	$0.00374
Haiku 4.5	$0.00014	$0.00187

Measured 7d ago against content hash 95326fcc6b97, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

cf-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 7d 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.

plugin-antigravity/skills/cf-tdd/SKILL.md · 174 lines

How it starts

The opening of the file, as written. The whole thing — 174 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implementation Workflow

CLI Requirement: NONE — Works without coding-friend-cli. See CLI requirements for the full matrix.

Custom Guide

Custom guide — auto-loaded below (if the raw command shows instead of its output, run it yourself):

bash "<plugin-root>/lib/load-custom-guide.sh" cf-tdd

If output is not empty, integrate returned sections: ## Before → before first step, ## Rules → apply throughout, ## After → after final step.

Mode Detection

Determine the implementation mode BEFORE doing anything else:

Check if the user's invocation or task description contains --add-tests
Check if .coding-friend/config.json exists and has "tdd": true
Check if the user's invocation or task description contains --auto (orthogonal to mode — autopilot can combine with both Direct and TDD mode).

Result:

--add-tests present OR tdd: true in config → TDD mode. Show: > TDD mode enabled — RED → GREEN → REFACTOR. → TDD mode: Read <plugin-root>/skills/cf-tdd/modes/tdd-mode.md now and follow RED→GREEN→REFACTOR.
Neither → Direct mode (default). Show: > Direct mode — implementing without new tests
Additionally, if --auto is present → Autopilot active. Show: > 🤖 Autopilot enabled — will auto-review, auto-fix Critical+Important, and auto-commit after implementation.

Skip Conditions

Check these BEFORE starting. If a skip condition is met, bypass the workflow entirely and proceed directly to implementation.

Auto-skip whitelist

If ALL changed/new files match these extensions, skip entirely — note why and proceed:

Styles: .css, .scss, .sass, .less, .styl
Docs: .md, .mdx, .txt, .rst
Config: .json, .yaml, .yml, .toml, .env, .ini, .lock, .config

`--no-tdd` flag

Deprecated — direct mode is now the default. If present, acknowledge and proceed in direct mode:

--no-tdd is now the default. Proceeding in direct mode.

Read the full file on GitHub · 174 lines

Files

What ships with it

2 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.

7d ago First seen · 174 lines · 136 tokens per session scan A 95326fcc6b97

Subscribe to this mod's changes

cf-tdd is a skill published in the GitHub repository dinhanhthi/coding-friend (3 stars, last pushed yesterday), licensed MIT. It adds 136 tokens to every session and 1,869 once invoked, about $0.0007 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 2026-08-31.

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