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 FradSer/dotclaude --skill tddgit clone --depth 1 https://github.com/FradSer/dotclaudeWrote 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/fradser/dotclaude/tdd)<a href="https://agentmods.dev/skills/fradser/dotclaude/tdd"><img src="https://agentmods.dev/badge/skills/fradser/dotclaude/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/fradser/dotclaude/tdd"><img src="https://agentmods.dev/badge/skills/fradser/dotclaude/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 | $0.00059 | $0.01269 |
| Opus 5.5 | $0.00024 | $0.00508 |
| Sonnet 5.5 | $0.00012 | $0.00254 |
| Haiku 4.5 | $0.00006 | $0.00127 |
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 23d 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 — 66 lines — stays where its author put it; the contents beside it link to each section on GitHub.
BDD-Driven TDD (Automation)
BDD cycles through three phases: Discovery (conversations → examples), Formulation (Gherkin scenarios), Automation (red-green-refactor, driven by BDD). This skill is the BDD-driven Automation reference — the how of test implementation, once /mattpocock:bdd has defined the what.
When invoked during /mattpocock:implement or /mattpocock:bdd, use this skill as the test-writing authority. The /mattpocock:bdd skill governs the scenario design and Iron Law; this skill governs the test code quality under BDD discipline.
CRITICAL: BDD scenarios come first
If you reached this skill directly (not via /mattpocock:bdd or /mattpocock:implement), stop and ask the user: "Have you defined the Gherkin scenarios for this behavior yet?"
- If no → invoke
/mattpocock:bddfirst to define the scenarios via Discovery → Formulation, then return here for Automation. - If yes → confirm the scenarios are in
.featurefiles or equivalent, then proceed with the red-green loop below.
What a good test is
Tests verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't. A good test reads like a specification: "user can checkout with valid cart" tells you exactly what capability exists, and it survives refactors because it doesn't care about internal structure.
See tests.md for examples and mocking.md for mocking guidelines.
Seams: where tests go
A seam is the public boundary you test at: the interface where you observe behavior without reaching inside. Tests live at seams, never against internals.
Test only at pre-agreed seams. Before writing any test, write down the seams under test and confirm them with the user. No test is written at an unconfirmed seam. You can't test everything, so agreeing the seams up front is how testing effort lands on the critical paths and complex logic instead of every edge case.
Ask: "What's the public interface, and which seams should we test?"
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.
- 23d ago First seen · 66 lines · 59 tokens per session scan A 950d326a55b6
tdd is a skill published in the GitHub repository FradSer/dotclaude (594 stars, last pushed 8d ago), licensed MIT. It adds 59 tokens to every session and 1,269 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-24.
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