tdd

tdd is a skill for Claude Code from mickeyyaya/evolve-loop. It costs 47 tokens per session (677 once invoked), scanned A, original, Apache-2.0.

A workflow step that writes tests before new code or bug fixes. TDD, or test-driven development, means defining the expected behavior in a failing test before implementing it.

In plain words
What is it for?
Use it before feature work or bug fixes to create failing regression or behavior tests, document the test contract, and pass a clear handoff to the implementation phase.
Why use it?
It makes the intended behavior explicit before implementation begins and ensures the new tests actually detect the missing behavior. This helps prevent changes that appear complete but are not tested.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions CLAUDE.md.

Part of the evo plugin — 26 skills, 27 commands, 107 agents, 3 hooks shipped together

Install

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.

agentmods
npx agentmods add skills/mickeyyaya/evolve-loop/tdd
Any agent
npx skills add mickeyyaya/evolve-loop --skill tdd
Clone the repo
git clone --depth 1 https://github.com/mickeyyaya/evolve-loop

Made for: Claude Code.

Or install evo, the plugin that ships this one along with the rest of its 26 skills, 27 commands, 107 agents, 3 hooks.

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 tdd

README.md
[![agentmods](https://agentmods.dev/badge/skills/mickeyyaya/evolve-loop/tdd.svg)](https://agentmods.dev/skills/mickeyyaya/evolve-loop/tdd)
Your own site
<a href="https://agentmods.dev/skills/mickeyyaya/evolve-loop/tdd"><img src="https://agentmods.dev/badge/skills/mickeyyaya/evolve-loop/tdd.svg" alt="Measured on agentmods" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 677 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00047 $0.00677
Opus 5 $0.00023 $0.00338
Sonnet 5 $0.00009 $0.00135
Haiku 4.5 $0.00005 $0.00068

Measured 2d ago against content hash e3a6a2b0dbc9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

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 2d 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.

skills/tdd/SKILL.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

tdd

Sprint 3 composable skill. Wraps the existing TDD-engineer phase with addyosmani-style structure. Mandatory hop before build.

When to invoke

  • After plan-review returns PROCEED, OR after Scout if plan-review disabled
  • Before any new feature implementation
  • Before any bug fix (write a regression test first)

When NOT to invoke

  • Eval-only cycles (no implementation needed)
  • Pure documentation cycles
  • Refactor cycles where existing tests provide coverage (verify first)

Workflow

Step Action Exit criteria
1 Read scout-report.md and plan-review.md Inputs verified
2 Write RED tests (must fail on current code) Tests exist; running them fails
3 Document the test contract in <workspace>/tdd-contract.md Contract written
4 Append section to <workspace>/team-context.md Bus updated for Builder

RED requirement

Tests MUST fail when run against the current codebase. A test that passes immediately is NOT a TDD contract — it does not exercise the new behavior. Builder will refuse to start without confirmed RED state.

Handoffs (beyond the contract artifact)

  • <workspace>/tdd-contract.md with sections: ## Tests Written, ## RED Verification, ## Contract for Builder
  • New/modified test files in the repo (Builder reads these)
  • <workspace>/team-context.md has populated ## TDD Contract section

Phase facts

Fact Value
Phase tdd (plan archetype, optional, gated by workflow.phase_enables.tdd=on)
Persona agents/evolve-tdd-engineer.md
Profile .evolve/profiles/tdd-engineer.json — CLI claude-tmux, tier balanced, single-writer
Inputs scout-report.md · plan-review-report.md
Artifact test-report.md (cycle workspace)

Output contract

Read the full file on GitHub · 72 lines

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. 2d ago First seen · 72 lines · 47 tokens per session scan A e3a6a2b0dbc9

Subscribe to this mod's changes

tdd is a skill published in the GitHub repository mickeyyaya/evolve-loop (5 stars, last pushed 2d ago), licensed Apache-2.0. It adds 47 tokens to every session and 677 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 2026-09-03.

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