rein: Command for Claude Code

.claude/commands/rein-inspect.md

rein-inspect is a command for Claude Code from jstxn/rein. It costs 24 tokens per session (1,261 once invoked), scanned A, original, MIT.

A documentation-first codebase inspection workflow that creates and maintains a map of an unfamiliar repository under .rein/codebase/. The map records evidence-backed architecture and boundary information for future readers.

In plain words
What is it for?
Use it when surveying a repository or subsystem and documenting its structure, key areas, and relationships without proposing implementation changes.
Why use it?
It gives developers a durable reference for understanding a large or unfamiliar codebase instead of repeatedly rediscovering how it is organized.

Command for Claude Code

Written for Claude Code: argument-hint in frontmatter.

This is jstxn/rein's own configuration. It tells Claude Code how to work on rein 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 rein configures →

View source ↗ jstxn/rein
Reuse

Borrowing it

Nothing to install: this file belongs to jstxn/rein. 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/jstxn/rein/main/.claude/commands/rein-inspect.md
Clone the repo
git clone --depth 1 https://github.com/jstxn/rein

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 rein-inspect

README.md
[![agentmods](https://agentmods.dev/badge/commands/jstxn/rein/rein-inspect/github.svg)](https://agentmods.dev/commands/jstxn/rein/rein-inspect)
Your own site
<a href="https://agentmods.dev/commands/jstxn/rein/rein-inspect"><img src="https://agentmods.dev/badge/commands/jstxn/rein/rein-inspect/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 rein-inspect

Your own site · 80×15
<a href="https://agentmods.dev/commands/jstxn/rein/rein-inspect"><img src="https://agentmods.dev/badge/commands/jstxn/rein/rein-inspect.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,261 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 $0.00024 $0.01261
Opus 5 $0.00012 $0.00630
Sonnet 5 $0.00005 $0.00252
Haiku 4.5 $0.00002 $0.00126

Measured 10d ago against content hash 247ee2112410, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

rein-inspect 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 10d 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/commands/rein-inspect.md · 175 lines

How it starts

The opening of the file, as written. The whole thing — 175 lines — stays where its author put it; the contents beside it link to each section on GitHub.

rein-inspect

rein-inspect is a documentation-first reconnaissance skill. Its job is to understand a codebase carefully and maintain a durable map of that understanding under .rein/codebase/.

The skill produces:

  • .rein/codebase/MAP.md
  • topical companion docs under .rein/codebase/

It observes and records. It does not recommend fixes.

When to Use

Use this skill when:

  • you need a high-signal map of an unfamiliar repo or subsystem
  • a project has grown beyond what one README can orient cleanly
  • you want durable codebase reference docs for future agents or humans
  • repeated work keeps re-discovering the same architecture or boundary facts

Do Not Use

Do not use this skill when:

  • the user asked for implementation, refactoring, or repair rather than inspection
  • the repo already has a maintained codebase map that only needs a tiny manual update
  • you only need a quick one-turn explanation instead of persistent docs
  • you are not prepared to read enough of the codebase to support the claims you write

Operating Boundaries

  • Read before writing.
  • Follow actual code evidence, not guessed architecture.
  • Keep output rooted at .rein/codebase/.
  • Preserve and update existing docs in place.
  • Add a new topical doc only when the inspected codebase reveals a real uncovered area.
  • Record observations and evidence-backed inferred risks.
  • Do not propose fixes, refactors, or migrations.
  • Do not edit application code as part of this skill unless the user explicitly asked for code changes outside the inspection pass.

Output Contract

Always maintain this docs tree:

.rein/
  codebase/
    MAP.md
    <topic>.md
    <topic>.md

MAP.md is the entrypoint. It should explain the major sections of the codebase and link to the topical docs.

Topical docs should be created from discovered domains, not a hard-coded list. Examples might include:

  • architecture.md
  • frontend.md
  • backend.md
  • data-flow.md
  • testing.md
  • tooling.md

The exact set depends on the repo.

Read the full file on GitHub · 175 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. 10d ago First seen · 175 lines · 24 tokens per session scan A 247ee2112410

Subscribe to this mod's changes

rein-inspect is a command published in the GitHub repository jstxn/rein (12 stars, last pushed 4mo ago), licensed MIT. It adds 24 tokens to every session and 1,261 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.