EXACT-Coding-Exercises: Skill for Claude Code

.claude/skills/green/SKILL.md

green is a skill for Claude Code from marcoemrich/EXACT-Coding-Exercises. It costs 73 tokens per session (511 once invoked), scanned A, original, MIT.

A manual step for the Green phase of TDD, a method where a failing test guides a small code change before later cleanup. It makes the smallest production change needed for the currently failing test and then stops.

In plain words
What is it for?
Use it to turn one active failing test into a passing test, while recording a prediction and checking whether the result matches it.
Why use it?
It lets you control one phase of the Red-Green-Refactor cycle instead of making broader changes or running the whole workflow at once.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: reads .claude/ paths.

This is marcoemrich/EXACT-Coding-Exercises's own configuration. It tells Claude Code how to work on EXACT-Coding-Exercises itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything EXACT-Coding-Exercises configures →

Reuse

Borrowing it

Nothing to install: this file belongs to marcoemrich/EXACT-Coding-Exercises. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/marcoemrich/EXACT-Coding-Exercises/main/.claude/skills/green/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/marcoemrich/EXACT-Coding-Exercises

Made for: Claude Code.

Wrote 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.

agentmods badge for green

README.md
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Your own site
<a href="https://agentmods.dev/skills/marcoemrich/exact-coding-exercises/green"><img src="https://agentmods.dev/badge/skills/marcoemrich/exact-coding-exercises/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.

agentmods 80×15 button for green

Your own site · 80×15
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Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 511 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00073 $0.00511
Opus 5.5 $0.00029 $0.00204
Sonnet 5.5 $0.00015 $0.00102
Haiku 4.5 $0.00007 $0.00051

Measured 1mo ago against content hash a39061b729e6, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

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 1mo 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.

.claude/skills/green/SKILL.md · 47 lines

What it actually says

Green — one phase, manually driven

This is a manual phase control, not a separate method. It runs step 3 of the predictive cycle and then stops. Use it when you want to steer Red-Green-Refactor yourself instead of invoking the whole exact-coding workflow. The method lives in one place; this skill only selects which part of it to execute now.

What to read

  1. .claude/skills/predictive-tdd/SKILL.md — sections Core rules and 3. Reach Green minimally. Those are binding as written.
  2. The matching profile under .claude/skills/predictive-tdd/stacks/ for the commands to run.
  3. .claude/skills/exact-coding-shared/human-in-the-loop.md for the prediction-mismatch rule.

What to do

Confirm there is an active behavioral Red to satisfy. If the suite is already green, say so and stop — there is nothing for this phase to do; offer red or refactor instead.

Then execute exactly step 3 of the cycle:

  • make the smallest production change likely to pass the active test, without anticipating inactive examples — hardcoded values and narrow conditionals are valid intermediate steps,
  • predict the focused test's outcome, including expected pass/fail and todo counts where the stack reports them,
  • run it and compare prediction with reality.

Where to stop

Stop after the active test is green. Report the change, the prediction, and the actual result. Do not refactor, and do not start the next behavior — even though Green has no default checkpoint in .claude/skills/exact-coding-shared/human-in-the-loop.md. The human invoked a single phase; that invocation is the checkpoint.

On a prediction mismatch, follow Prediction mismatch in the Predictive TDD skill and stop there. Never change production behavior merely to make an unexplained failure disappear.

Changes

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.

  1. 1mo ago First seen · 47 lines · 73 tokens per session scan A a39061b729e6

Subscribe to this mod's changes

green is a skill published in the GitHub repository marcoemrich/EXACT-Coding-Exercises (18 stars, last pushed 1mo ago), licensed MIT. It adds 73 tokens to every session and 511 once invoked, about $0.0003 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 2026-09-20.