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 skills add PANYUXIN6/pyx-skills --skill tddgit clone --depth 1 https://github.com/PANYUXIN6/pyx-skillsWrote 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/panyuxin6/pyx-skills/tdd)<a href="https://agentmods.dev/skills/panyuxin6/pyx-skills/tdd"><img src="https://agentmods.dev/badge/skills/panyuxin6/pyx-skills/tdd/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.
<a href="https://agentmods.dev/skills/panyuxin6/pyx-skills/tdd"><img src="https://agentmods.dev/badge/skills/panyuxin6/pyx-skills/tdd.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00066 | $0.00524 |
| Opus 5 | $0.00033 | $0.00262 |
| Sonnet 5 | $0.00013 | $0.00105 |
| Haiku 4.5 | $0.00007 | $0.00052 |
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 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.
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 — 42 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Drive Implementation Test First
Own the sequencing between confirmed behavior, failing evidence, implementation, and local refactoring. Use testing-guidelines to select and validate test evidence; this skill owns only the test-first development loop.
Establish Behavior Before RED
Start from a requirement, contract, acceptance criterion, invariant, or confirmed regression. Resolve ambiguities that would materially change public or user-visible behavior before entering the loop. Do not let a test invent new requirements.
Use this progression for each coherent slice:
Requirement -> Acceptance Criteria -> Test Cases -> RED -> GREEN -> REFACTOR
Keep the TDD Gates
- Observe a meaningful RED. Run the selected evidence before implementation and accept the red only when the intended behavior is absent or broken. Treat build, fixture, import, and environment failures as setup failures.
- Implement a reasonable GREEN. Add only the production behavior required by the current slice, while preserving existing architecture and contracts. Do not trade maintainability or correctness for the fastest possible pass.
- Refactor locally. Improve only what the current implementation justifies, keep all relevant evidence green, and avoid unrelated cleanup or broader redesign.
Work in Coherent Vertical Slices
For each remaining behavior:
- Use
testing-guidelinesto select the smallest credible evidence for that behavior. - Add the evidence and observe a valid red.
- Implement only what that slice requires.
- Run the focused evidence and keep it green.
- Refactor only when it improves the current slice, then verify green again.
A slice is one coherent behavior or contract, not necessarily one test function. Finish a slice before starting an independent behavior so each red and green has a clear cause.
Handle Cases Without a Genuine RED
For characterization tests or behavior-preserving refactors, a genuine red may be unsafe or impossible because the intended behavior already exists. Explain the alternative evidence, preserve current behavior, and do not simulate a meaningless failure merely to imitate the TDD sequence.
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.
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.
- 10d ago First seen · 42 lines · 66 tokens per session scan A 04a1c4aacc7e
tdd is a skill published in the GitHub repository PANYUXIN6/pyx-skills (6 stars, last pushed 4d ago), licensed MIT. It adds 66 tokens to every session and 524 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 2026-08-31.
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nw-fp-clojure
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strict-tdd
Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.
mobiai-mobile-tdd
You MUST use this before writing any implementation code for a mobile feature, bug fix, refactor, or behavior change. Tests come before implementation — no exceptions.