boxel: Skill for Claude Code

.claude/skills/review-branch/SKILL.md

review-branch is a skill for Claude Code from cardstack/boxel. It costs 30 tokens per session (316 once invoked), scanned A, original, MIT.

A procedure for reviewing the changes on a Git branch, a separate line of code changes. It compares the branch with the main branch and checks the code, risks, performance, style, and test coverage.

In plain words
What is it for?
Use it for pull-request review, especially when you need a summary of changed files, prioritized issues, and suggested review comments.
Why use it?
It gives a reviewer a consistent way to find bugs, security problems, slow operations, and missing tests before changes are merged. It also produces review points that can be shared with the author.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

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

Reuse

Borrowing it

Nothing to install: this file belongs to cardstack/boxel. 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/cardstack/boxel/main/.claude/skills/review-branch/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/cardstack/boxel

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 review-branch

README.md
[![agentmods](https://agentmods.dev/badge/skills/cardstack/boxel/review-branch/github.svg)](https://agentmods.dev/skills/cardstack/boxel/review-branch)
Your own site
<a href="https://agentmods.dev/skills/cardstack/boxel/review-branch"><img src="https://agentmods.dev/badge/skills/cardstack/boxel/review-branch/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 review-branch

Your own site · 80×15
<a href="https://agentmods.dev/skills/cardstack/boxel/review-branch"><img src="https://agentmods.dev/badge/skills/cardstack/boxel/review-branch.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 316 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 $0.00030 $0.00316
Opus 5.5 $0.00012 $0.00126
Sonnet 5.5 $0.00006 $0.00063
Haiku 4.5 $0.00003 $0.00032

Measured 5d ago against content hash 82f08bc83c85, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

review-branch 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 5d 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/skills/review-branch/SKILL.md · 32 lines

What it actually says

Code Review Guide

Check out the branch $ARGUMENTS and give me a thorough guided tour of the changes.

Steps

  1. Run git fetch origin then git checkout $ARGUMENTS
  2. Run git diff main...$ARGUMENTS --stat to get an overview of changed files
  3. Run git log main...$ARGUMENTS --oneline to understand the commit history
  4. For each changed file, run git diff main...$ARGUMENTS -- <file> and analyze the diff

For each file, provide:

  • Summary: What changed and the likely intent
  • Risks: Bugs, security issues, race conditions, error handling gaps
  • Performance: N+1 queries, unnecessary allocations, missing indexes
  • Style: Naming, structure, consistency with surrounding code
  • Testing gaps: What's untested or under-tested

At the end, provide:

  • An overall assessment (approve / request changes / needs discussion)
  • A prioritized list of the top issues to raise in review
  • Suggested review comments I can paste directly into the PR
  • Suggested files for a human reviewer to pay attention to
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. 5d ago First seen · 32 lines · 30 tokens per session scan A 82f08bc83c85

Subscribe to this mod's changes

review-branch is a skill published in the GitHub repository cardstack/boxel (27 stars, last pushed today), licensed MIT. It adds 30 tokens to every session and 316 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-10-21.

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