Application
Coding
Micro-agent
1AI 2writes 3code 4passing 5your 6tests
the six Ws · specification
W1
Who
Maintained by Builder.io as an open-source project.
W2
What
A CLI agent that iteratively writes and fixes code until it passes the tests you provide.
W3
Where
Runs locally as a Node CLI in your project directory.
W4
When
Reach for it when a task is expressible as tests and you want a passing implementation.
W5
Why
The test-driven loop constrains the AI, producing verifiable, focused code.
W6
With
An LLM API key (OpenAI or Anthropic) and Node.js.
W7
Watch
Vendor-backed open-source; runs your test commands and edits files locally in a bounded loop. MIT licensed, small but stable.