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-red/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-red)<a href="https://agentmods.dev/skills/mrlarson2007/copilot-tdd-harness/tdd-red"><img src="https://agentmods.dev/badge/skills/mrlarson2007/copilot-tdd-harness/tdd-red/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-red"><img src="https://agentmods.dev/badge/skills/mrlarson2007/copilot-tdd-harness/tdd-red.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 | $0.00039 | $0.00349 |
| Opus 5 | $0.00019 | $0.00175 |
| Sonnet 5 | $0.00008 | $0.00070 |
| Haiku 4.5 | $0.00004 | $0.00035 |
Grade A, and why
tdd-red 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.
What it actually says
TDD Red Phase Skill
Purpose
- Add one failing unit test for the current scenario slice
- Assert only one behavior per test
- Prioritize readability and intent
- No production code changes in this phase
- No test refactoring except for clarity
Inputs
- Scenario slice
- Skill and asset references
- Project testing patterns from
.github/instructions/tdd-patterns.instructions.md - Canonical RED style guide placeholder at
.github/skills/tdd-red/assets/project-testing-patterns.md
Outputs
- Failing test artifact
- Failure output and rationale
Steps
- Load
.github/skills/tdd-red/assets/project-testing-patterns.mdfirst, then load core asset files for assertion quality, failure verification, and anti-patterns - Write a single failing test for the scenario
- Use
tdd-test-runwith atest_run_requestcontract whose expected result is the specific failing test and failure signal for this RED step - If the observed result does not match the expected RED outcome, revert only
the scoped test changes and retry or escalate based on the
test_run_result - Return contract output
Completion Checks
- Only one new failing test
- Failure is for the intended assertion
- Test is readable and focused
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 · 44 lines · 39 tokens per session scan A d7563904436b
tdd-red is a skill published in the GitHub repository mrlarson2007/copilot-tdd-harness (5 stars, last pushed 3mo ago), licensed MIT. It adds 39 tokens to every session and 349 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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