implement-with-tdd SKILL.md skillA
implement-with-tdd from thoughtbot/rails-consultant is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add thoughtbot/rails-consultant/implement-with-tdd@git:20261106.ce8ab68Pins git:20261106.ce8ab68 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- thoughtbot/rails-consultant
- Path
skills/implement-with-tdd/SKILL.md- Versions recorded
- 1
- Latest version
- git:20261106.ce8ab68, committed Nov 6, 2026
- Size
- 7,159 bytes
- Repository stars
- 29
- License
- MIT
Implement a SPEC, plan, or feature outside-in, with TDD.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Implement with TDD Work from the outside in and let each failure name the next move. Stop at shameless green; a later step refactors. The discipline exists because you're fluent enough to write plausible code for almost anything, and plausible isn't correct. A failing test tells them apart. ## What you were handed The thing to build: `$ARGUMENTS` If that's empty, ask. If it's a path, read it. Take the acceptance criteria as the scope. Those are behavior, and behavior is what you can test. A suggested design, a test path, an ordering: that's a guess from a session that never ran the suite. Yours will run it, so your evidence is better. Where the repo contradicts the plan the repo is right — say so rather than diverge quietly. A `## Where to look` section is the exception to that distrust, not to the scope rule. Those paths are where a prior session already found the relevant code, so they save you the search and not the judgment: open them before you go looking for anything else, and treat nothing on the list as work you owe. The criteria are still the whole scope. If a path is gone or turns out to be irrelevant, skip it and say so in the report — don't edit the SPEC. …
Read the whole file at its exact version.
How to install
mdr add thoughtbot/rails-consultant/implement-with-tdd@sha256:8ba6df798a4d3f48The line at the top of this page pins the label git:20261106.ce8ab68, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_n6lfsawc6bzzlud4)
1 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Nov 6, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (7159 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
thoughtbot/rails-consultant · 29 stars · license MIT · pushed 2026-11-07 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_n6lfsawc6bzzlud4 GET https://markdownregistry.com/api/v1/resolve?ref=thoughtbot/rails-consultant/implement-with-tdd GET https://markdownregistry.com/api/v1/blob/8ba6df798a4d3f483a3ca16c605c1d392549f7333679342f0f7d97a0ce4cfe42
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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