A formatter, linter, and language toolchain for web projects.
Biome keeps repository-wide rules in one file and puts testing, review, changeset, and documentation work in skills. Claims about the codebase need source evidence. The guide also names generator commands and limits agent-written contributor messages.
├── ├── · symlink → CONTRIBUTING.md ├── .claude │ └── skills │ ├── biome-code-review │ │ └── │ ├── changeset │ │ └── │ ├── doc-comments │ │ └── │ ├── testing-codegen │ │ └── │ └── ├── .github │ └── └──
01 / Behavioral framing
A claimed function, behavior, or convention needs a file and line, an excerpt, or a reproducible command. When that evidence is unavailable, the response must say so instead of filling the gap with remembered behavior.
Source excerpt starting at line 12.- Do not claim a Biome function, module, behavior, or convention exists without an exact file and line, a source excerpt, or a reproducible command.
02 / Behavioral framing
The final review follows implementation and verification, using a fresh subagent when available. Its input contains the scope and business requirements while withholding suspected defects and expected outcomes.
Source excerpt starting at line 49.- Provide only the review scope and intended business requirements. Do not include suspected defects, implementation hints, prior findings, or expected outcomes.
03 / Generated file guards
The file names the artifacts that must accompany a grammar change. Lint-rule and assist renames have a separate generator pair, while some full analyzer outputs can be left to CI.
Source excerpt starting at line 34.If you change an `.ungram` file, run:- `just gen-grammar <lang>`- `just gen-formatter --allow-dirty`
04 / Contribution etiquette
Writing code and opening a PR from supplied text have different boundaries. The agent must preserve the template and disclose assistance, but the contributor authors the description and other communication.
Source excerpt starting at line 61.- Do not write PR descriptions or contributor communication. `CONTRIBUTING.md` requires the contributor to author that prose.
05 / Router files
Review, generated tests, changesets, and comments each have a named skill. Even an incidental comment edit activates the comment guide, while the catalog defines the broader trigger boundaries.
Source excerpt starting at line 68.Load [doc-comments](./.claude/skills/doc-comments/SKILL.md) whenever editing `//`, `///`, or `//!` comments, including comments added incidentally.
These instructions explain how to work in Biome. Modem shows your agents what customers said, who is affected, and what changed.