biome

biome is a skill for Claude Code, Codex from managedcode/dotnet-skills. It costs 126 tokens per session (1,630 once invoked), scanned A, original, MIT.

A formatter and linter for JavaScript, TypeScript, CSS, JSON, GraphQL, and HTML frontend files. It can also organize imports, combining several common code-cleanup tasks.

In plain words
What is it for?
Use it to format and lint frontend assets, organize imports, and run consistent checks in local development or CI.
Why use it?
It gives a project one place to check formatting, common mistakes, and import order. This can reduce overlap between separate frontend style tools.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions AGENTS.md.

Good fit Use it to format and lint frontend assets, organize imports, and run consistent checks in local development or CI.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/managedcode/dotnet-skills/biome
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.

Any agent
npx skills add managedcode/dotnet-skills --skill biome
Clone the repo
git clone --depth 1 https://github.com/managedcode/dotnet-skills

Made for: Claude Code, Codex.

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 biome

README.md
[![agentmods](https://agentmods.dev/badge/skills/managedcode/dotnet-skills/biome.svg)](https://agentmods.dev/skills/managedcode/dotnet-skills/biome)
Your own site
<a href="https://agentmods.dev/skills/managedcode/dotnet-skills/biome"><img src="https://agentmods.dev/badge/skills/managedcode/dotnet-skills/biome.svg" alt="Measured on agentmods" height="20"></a>
Per session 126 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,630 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 3 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium MCP Rug Pull · line 64
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 66
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 67
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
How audits are shown
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 $0.00126 $0.01630
Opus 5 $0.00063 $0.00815
Sonnet 5 $0.00025 $0.00326
Haiku 4.5 $0.00013 $0.00163

Measured 3d ago against content hash 523c595f1135, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

biome 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 3d 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

2 near-identical copies found in the catalogue:

catalog/Tools/Biome/skills/biome/SKILL.md · 114 lines

How it starts

The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Biome for Frontend Assets in .NET Repositories

Trigger On

  • the repo has biome.json, @biomejs/biome, or the user asks for a faster all-in-one frontend formatter-linter stack
  • the repo wants one tool for formatting, linting, and import organization across JS, TS, CSS, JSON, GraphQL, or HTML
  • the team is comparing Biome against ESLint plus Prettier or wants to simplify the current stack

Do Not Use For

  • repos that rely on ESLint plugins or framework-specific rules Biome does not cover yet
  • runtime site audits such as headers, accessibility, and SEO; route that to webhint
  • cases where a dedicated CSS or HTML tool is still the deliberate owner and no migration is requested

Inputs

  • the nearest AGENTS.md
  • package.json
  • biome.json or biome.jsonc
  • current ownership across ESLint, Prettier, Stylelint, and import ordering

Workflow

  1. Decide ownership first:
    • Biome as the main formatter and linter
    • Biome only for formatting
    • Biome in coexistence with ESLint for plugin gaps
  2. Prefer a repo-local pinned install so CI and developer machines use the same version.
  3. Generate biome.json only after confirming what the repo wants Biome to own.
  4. Add repeatable scripts to package.json, for example:
    • biome check .
    • biome check . --write
  5. Keep file ownership explicit:
    • Biome can own formatting, linting, and import sorting
    • webhint still owns site-runtime audits
    • ESLint may stay for plugin-heavy cases the repo intentionally keeps
  6. Start migrations with check and bounded folders before flipping the whole repo to --write.
  7. Re-run the frontend build and tests after broad formatting or lint-fix passes.

Current Upstream Notes

  • Biome CLI 2.5.12 fixes Astro expression parsing, nested JSX attribute sorting, Unicode stdin/stdout corruption, and repeated dependency scanning. Validate representative Astro/TSX files, Unicode input, and formatter idempotence before dropping workarounds.
  • noFloatingPromises now handles cyclic imports and awaited Promise aliases more accurately; awaiting an array of Promises still leaves its elements unhandled. Use Promise.all or an explicit awaited loop when appropriate. New Nursery rules remain opt-in, including useFlatMathMinMax, useModernMathApis, noThisOutsideOfClass, noVueDeprecatedScopedSlots, and noBunModules.

Read the full file on GitHub · 114 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 3d ago Changed · +3 lines 523c595f1135
  2. 4d ago First seen · 111 lines · 126 tokens per session scan A 35b1a22521f6

Subscribe to this mod's changes

biome is a skill published in the GitHub repository managedcode/dotnet-skills (477 stars, last pushed 2d ago), licensed MIT. It adds 126 tokens to every session and 1,630 once invoked, about $0.0006 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 2026-09-03.

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