cycle

A command that runs one complete TDD cycle: write a failing test, add the smallest implementation that passes it, then improve the code. TDD means using tests to guide development in these stages.

In plain words
What is it for?
Use it when implementing one focused behavior from a task or conversation. It covers the test, minimal code, and refactoring phases in sequence.
Why use it?
It gives a small feature or behavior a structured path from requirement to working code. The tests provide a check that the implementation still behaves as intended while the code is cleaned up.

Command for Claude Code

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 commands/wbern/agent-instructions/cycle
Clone the repo
git clone --depth 1 https://github.com/wbern/agent-instructions

Made for: Claude Code.

Per session 16 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,242 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 $0.00016 $0.01242
Opus 5 $0.00008 $0.00621
Sonnet 5 $0.00003 $0.00248
Haiku 4.5 $0.00002 $0.00124

Measured 2d ago against content hash 511255558182, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cycle 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.

Origin

Copies of this mod

6 near-identical copies found in the catalogue:

  • green — 92% identical, 8 lines differ
  • red — 91% identical, 16 lines differ
  • tdd — 89% identical, 27 lines differ
  • spike — 89% identical, 8 lines differ
  • issue — 86% identical, 82 lines differ
  • refactor — 86% identical, 32 lines differ
.claude/commands/cycle.md · 115 lines

How it starts

The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.

User arguments:

Cycle: $ARGUMENTS

End of user arguments

RED+GREEN+REFACTOR (one cycle) PHASE! Apply the below to the user input above.

General Guidelines

Output Style

  • Never explicitly mention TDD in code, comments, commits, PRs, or issues
  • Write natural, descriptive code without meta-commentary about the development process
  • The code should speak for itself - TDD is the process, not the product

Beads is available for task tracking. Use mcp__beads__* tools to manage issues (the user interacts via bd commands).

Plan File Restriction

NEVER create, read, or update plan.md files. Claude Code's internal planning files are disabled for this project. Use other methods to track implementation progress (e.g., comments, todo lists, or external tools).

(If there was no info above, fallback to:

  1. Context of the conversation, if there's an immediate thing
  2. bd ready to see what to work on next and start from there)

TDD Fundamentals

The TDD Cycle

The foundation of TDD is the Red-Green-Refactor cycle:

  1. Red Phase: Write ONE failing test that describes desired behavior

    • The test must fail for the RIGHT reason (not syntax/import errors)
    • Only one test at a time - this is critical for TDD discipline
      • Exception: For browser-level tests or expensive setup (e.g., Storybook *.stories.tsx), group multiple assertions within a single test block to avoid redundant setup - but only when adding assertions to an existing interaction flow. If new user interactions are required, still create a new test. Split files by category if they exceed ~1000 lines.
    • Adding a single test to a test file is ALWAYS allowed - no prior test output needed
    • Starting TDD for a new feature is always valid, even if test output shows unrelated work
    • For DOM-based tests, use data-testid attributes to select elements rather than CSS classes, tag names, or text content
    • Avoid hard-coded timeouts both in form of sleep() or timeout: 5000 etc; use proper async patterns (waitFor, findBy*, event-based sync) instead and rely on global test configs for timeout settings

Read the full file on GitHub · 115 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 · 115 lines · 16 tokens per session scan A 511255558182

Subscribe to this mod's changes

cycle is a command published in the GitHub repository wbern/agent-instructions (168 stars, last pushed 3mo ago), licensed MIT. It adds 16 tokens to every session and 1,242 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 2026-08-30.