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.
npx agentmods add skills/marcoemrich/exact-coding-exercises/tddnpx skills add marcoemrich/EXACT-Coding-Exercises --skill tddgit clone --depth 1 https://github.com/marcoemrich/EXACT-Coding-ExercisesWrote 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.
[](https://agentmods.dev/skills/marcoemrich/exact-coding-exercises/tdd)<a href="https://agentmods.dev/skills/marcoemrich/exact-coding-exercises/tdd"><img src="https://agentmods.dev/badge/skills/marcoemrich/exact-coding-exercises/tdd.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00070 | $0.02010 |
| Opus 5 | $0.00035 | $0.01005 |
| Sonnet 5 | $0.00014 | $0.00402 |
| Haiku 4.5 | $0.00007 | $0.00201 |
Grade A, and why
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 4d 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.
How it starts
The opening of the file, as written. The whole thing — 186 lines — stays where its author put it; the contents beside it link to each section on GitHub.
TDD Rules — Hybrid (v6, exact-coding baseline)
⚠️ CRITICAL: Skill + Subagent Usage is MANDATORY
This workflow is a hybrid of v4 and v5:
/test-list,/red,/greenrun as Skills in the main context (like v5) — they share state, so the model keeps test list, last error, and current implementation in working memory.- Refactor runs as a Task subagent with isolated context (like v4) — the refactor agent sees only the current source/tests, not the full red/green history. Hypothesis: refactoring benefits most from a fresh perspective free of implementation bias.
Do NOT perform TDD phases without invoking the appropriate skill or agent.
Before Starting Any TDD Work — Complete This Checklist:
- Have I been asked to implement something using TDD?
- Am I about to write tests or implementation code?
- STOP — Use the Skill tool (test-list/red/green) or the Task tool (refactor)
- NEVER write tests, code, or refactorings directly — ALWAYS delegate
Which Tool to Use:
| Phase | Mechanism | Invoke With |
|---|---|---|
| Example Mapping (optional, before TDD) | Skill | Skill({ skill: "example-mapping" }) |
| Test List | Skill (main context) | Skill({ skill: "test-list" }) |
| Red Phase | Skill (main context) | Skill({ skill: "red" }) |
| Green Phase | Skill (main context) | Skill({ skill: "green" }) |
| Refactor Phase | Task subagent (isolated context) | Task({ subagent_type: "refactor", prompt: ... }) |
| Final quality pass (optional, manual) | Skill | Skill({ skill: "end-refactor" }) |
If you find yourself writing test code, implementation code, or a refactoring without invoking the right tool first, you are doing it WRONG.
Overview
This project follows strict Test-Driven Development practices using the Red-Green-Refactor cycle. v6 keeps red and green in a shared context so the predictions, error messages, and minimal implementations stay coherent — and isolates refactoring so the model evaluates the resulting code on its own merits.
What ships with it
3 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.
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.
- 4d ago First seen · 186 lines · 70 tokens per session scan A d6cb98238b90
tdd is a skill published in the GitHub repository marcoemrich/EXACT-Coding-Exercises (13 stars, last pushed 15d ago), licensed MIT. It adds 70 tokens to every session and 2,010 once invoked, about $0.0003 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.
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