Borrowing it
Nothing to install: this file belongs to mrlarson2007/copilot-tdd-harness. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mrlarson2007/copilot-tdd-harness/master/.github/skills/tdd-green/SKILL.mdgit clone --depth 1 https://github.com/mrlarson2007/copilot-tdd-harnessWrote 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/mrlarson2007/copilot-tdd-harness/tdd-green)<a href="https://agentmods.dev/skills/mrlarson2007/copilot-tdd-harness/tdd-green"><img src="https://agentmods.dev/badge/skills/mrlarson2007/copilot-tdd-harness/tdd-green/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/mrlarson2007/copilot-tdd-harness/tdd-green"><img src="https://agentmods.dev/badge/skills/mrlarson2007/copilot-tdd-harness/tdd-green.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 | $0.00035 | $0.00566 |
| Opus 5 | $0.00017 | $0.00283 |
| Sonnet 5 | $0.00007 | $0.00113 |
| Haiku 4.5 | $0.00003 | $0.00057 |
Grade A, and why
tdd-green 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 9d 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 — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.
TDD Green Phase Skill
Purpose
- Write the simplest code to make the failing test pass
- Do not modify tests in this phase
- No refactoring or generalization
- Commit after tests pass
Inputs
- Failing test id
- Skill and asset references
- Project code style patterns from
.github/instructions/tdd-patterns.instructions.md - Canonical GREEN style guide placeholder at
.github/skills/tdd-green/assets/project-code-style-patterns.md
Outputs
- Changed production files
- Test pass summary
Steps
- Load
.github/skills/tdd-green/assets/project-code-style-patterns.mdfirst, then load core asset files for minimal implementation, anti-patterns, and commit discipline - Check whether the RED test compiles.
- If the test references missing production symbols (types, methods, fields), the only allowed edit is the smallest possible compile-only stub — no behavior.
- Run the narrow test again. It must now compile and fail at runtime/assertion level before proceeding.
- This is the distinction between structural red (compile failure) and behavioral red (assertion failure). Both are RED; behavior must not be added until you are at behavioral red.
- Judge the next GREEN move before editing production code.
- Ask whether the change is the dumbest possible thing that makes only the current test pass.
- If the change also solves untested cases, tries to generalize, or looks like the feature instead of the slice, it is too broad.
- Prefer a constant, hardcoded branch, or the narrowest exact-case behavior the current test demands.
- Do not move from behavioral red into generalized implementation just because the change is small.
- Write minimal code to pass the test
- Use
tdd-test-runwith atest_run_requestcontract whose expected result is a passing narrow check for the protected test or slice - If the observed result does not match the expected GREEN outcome, revert only the scoped production changes and return to the preceding GREEN decision point
- Run the broader validation required by project policy through
tdd-test-runbefore reporting GREEN complete - Return contract output
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.
- 9d ago First seen · 54 lines · 35 tokens per session scan A 5151c4d13777
tdd-green is a skill published in the GitHub repository mrlarson2007/copilot-tdd-harness (5 stars, last pushed 3mo ago), licensed MIT. It adds 35 tokens to every session and 566 once invoked, about $0.0002 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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