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/archive228/loopkit/write-failing-test-firstnpx skills add Archive228/loopkit --skill write-failing-test-firstgit clone --depth 1 https://github.com/Archive228/loopkitWrote 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/archive228/loopkit/write-failing-test-first)<a href="https://agentmods.dev/skills/archive228/loopkit/write-failing-test-first"><img src="https://agentmods.dev/badge/skills/archive228/loopkit/write-failing-test-first.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 | $0.00029 | $0.00188 |
| Opus 5 | $0.00015 | $0.00094 |
| Sonnet 5 | $0.00006 | $0.00038 |
| Haiku 4.5 | $0.00003 | $0.00019 |
Grade A, and why
write-failing-test-first 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 today.
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.
What it actually says
Write the Failing Test First
The only proof you fixed a bug is a test that failed before and passes after.
- Write the smallest test that reproduces the reported behavior.
- Run it. Watch it fail for the right reason (read the assertion, not just red).
- Now fix the code.
- Run the test. It passes. Run the FULL suite — you didn't break anything else. If you can't write the test easily, the architecture is telling you something (tight coupling). Say so. Never: fix first, test after (you'll write a test that passes regardless). Never: skip the watch-it-fail step.
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.
- today First seen · 14 lines · 29 tokens per session scan A b34424dcc62d
write-failing-test-first is a skill published in the GitHub repository Archive228/loopkit (755 stars, last pushed 1mo ago), licensed MIT. It adds 29 tokens to every session and 188 once invoked, about $0.0001 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 2026-09-03.
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