Install Anti-Slop Oxlint Rules
dmmulroy/anti-slop
Installs, updates or migrates the vendored anti-slop Oxlint plugin in a repository, keeping local rule changes and the plugin's license and provenance files.
A skill your agent uses when implementing or modifying Biome parser behavior, including .ungram grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures.
Install Parser Development
$ npx skills add biomejs/biome --skill parser-development -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install biomejs/biome parser-development --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/biomejs/biome.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/parser-development .claude/skills/parser-development && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "parser-development" agent skill from https://github.com/biomejs/biome/tree/main/.agents/skills/parser-development into .claude/skills/parser-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "parser-development", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/biomejs/biome/tree/main/.agents/skills/parser-developmentType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add biomejs/biome --skill parser-development -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install biomejs/biome parser-development --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/biomejs/biome.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/parser-development .agents/skills/parser-development && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "parser-development" agent skill from https://github.com/biomejs/biome/tree/main/.agents/skills/parser-development into .agents/skills/parser-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "parser-development", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add biomejs/biome --skill parser-development -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install biomejs/biome parser-development --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/biomejs/biome.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/parser-development .cursor/skills/parser-development && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "parser-development" agent skill from https://github.com/biomejs/biome/tree/main/.agents/skills/parser-development into .cursor/skills/parser-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "parser-development", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/biomejs/biome.git --path .agents/skills/parser-development--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add biomejs/biome --skill parser-development -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install biomejs/biome parser-development --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/biomejs/biome.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/parser-development .gemini/skills/parser-development && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "parser-development" agent skill from https://github.com/biomejs/biome/tree/main/.agents/skills/parser-development into .gemini/skills/parser-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "parser-development", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install biomejs/biome parser-developmentInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add biomejs/biome --skill parser-development -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/biomejs/biome.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/parser-development .github/skills/parser-development && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "parser-development" agent skill from https://github.com/biomejs/biome/tree/main/.agents/skills/parser-development into .github/skills/parser-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "parser-development", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add biomejs/biome --skill parser-development -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install biomejs/biome parser-development --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/biomejs/biome.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/parser-development .opencode/skills/parser-development && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "parser-development" agent skill from https://github.com/biomejs/biome/tree/main/.agents/skills/parser-development into .opencode/skills/parser-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "parser-development", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
parser-development- GitHub stars
- 26k
- Token cost
- ~1.2k tokens
- SKILL.md length
- 563 words
- Files
- 1
- Skills in repo
- 12
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
A skill your agent uses when implementing or modifying Biome parser behavior, including .ungram grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures.
- Works in 6 steps: Inspect the language grammar and… → Add or adjust focused ok/ and error/… → Update the grammar when the typed tree… → …
- Modifying Biome parser behavior
- SKILL.md covers Workflow, Grammar, Presence Contract and Error Recovery, plus 5 more sections
- Calls just
What it does
Parser Development is an agent skill from biomejs/biome, published by the product's own GitHub organization. Use this skill when implementing or modifying Biome parser behavior, including .ungram grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures. Do not use merely for consuming an existing AST/CST.
Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: Designed for coding agents working on the Biome codebase (github.com/biomejs/biome).
It sits in Development, covering Linting and formatting. The repository describes itself as: A toolchain for web projects, aimed to provide functionalities to maintain them. Biome offers formatter and linter, usable via CLI and LSP. The licence is Apache-2.0.
When your agent uses it
- Modifying Biome parser behavior
- Including .ungram grammars
- Separated lists
- Parser fixtures
Example prompts
- “/parser-development”
Requirements
- Compatibility (from SKILL.md): Designed for coding agents working on the Biome codebase (github.com/biomejs/biome).
Workflow steps
6 steps, taken from the first numbered list in SKILL.md.
- Inspect the language grammar and neighboring parse rules.
- Add or adjust focused ok/ and error/ fixtures before changing recovery behavior.
- Update the grammar when the typed tree shape changes.
- Regenerate syntax and factory artifacts after .ungram changes.
- Implement parser logic with explicit presence tests and bounded recovery.
- Run the language parser's focused tests and inspect snapshots.
What it can do on your machine
Read from SKILL.md and the folder at commit c870caa. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
just
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Compatibility
Designed for coding agents working on the Biome codebase (github.com/biomejs/biome).
From compatibility in the SKILL.md frontmatter.
Context cost
Parser Development loads about 1.2k tokens when it runs. Until then it costs about 65 tokens; SKILL.md has 563 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from biomejs/biome at commit c870caa, republished under its Apache-2.0 licence (© biomejs). 563 words, ~1,156 tokens.
Download SKILL.mdSave it as
.claude/skills/parser-development/SKILL.md (or your agent's skills folder).- name
- parser-development
- description
- Use this skill when implementing or modifying Biome parser behavior, including `.ungram` grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures. Do not use merely for consuming an existing AST/CST.
- compatibility
- Designed for coding agents working on the Biome codebase (github.com/biomejs/biome).
Parser Development
Use crates/biome_parser/CONTRIBUTING.md as the canonical parser guide. Read the section matching the current grammar, lexer, parse-rule, or recovery task.
Workflow
- Inspect the language grammar and neighboring parse rules.
- Add or adjust focused
ok/anderror/fixtures before changing recovery behavior. - Update the grammar when the typed tree shape changes.
- Regenerate syntax and factory artifacts after
.ungramchanges. - Implement parser logic with explicit presence tests and bounded recovery.
- Run the language parser's focused tests and inspect snapshots.
Grammar
Grammar files under xtask/codegen/ define typed syntax nodes and fields. Follow existing language naming:
- prefix nodes with the language name;
- name unions with
Any; - use
Bogusnodes for recoverable invalid syntax; - end list node names with
List; - represent lists as present, possibly empty nodes rather than optional fields.
After a grammar change, run:
just gen-grammar <lang>This updates generated syntax nodes, syntax kinds, factories, macros, and language-specific mappings. Parser rules remain hand-written.
Presence Contract
A parse function returns Absent only when it has consumed no tokens. Test the first distinguishing token before calling start, bump, eat, expect, or another parser that can advance.
Use:
expectfor required tokens that should create a diagnostic when absent;eatfor optional tokens;.ok()for optional nodes;.or_add_diagnostic(...)for required nodes;- typed recovery for malformed nodes that should remain in the CST.
Do not use backtracking where a bounded lookahead or a more precise presence test can distinguish the syntax.
Error Recovery
Recovery must preserve following valid syntax and produce a bogus node permitted by the grammar at that position.
A recovery set normally includes the nearest relevant:
- list separator;
- list or block terminator;
- statement boundary;
- token that starts the next valid construct.
Do not copy a recovery set from an unrelated grammar position. Verify which tokens the caller expects after the failed parse.
Lists
Use the parser infrastructure's list traits instead of open-coded loops when their contract matches the grammar.
For separated lists, verify:
- the parser recognizes the enclosing terminator;
- separator handling agrees with trailing-separator grammar;
- a malformed element makes progress or stops;
- recovery cannot consume the enclosing terminator;
- an empty list still produces the required list node.
Show full SKILL.md (206 more words)Show less
Lexer and Token Source
Follow the current Lexer and buffered token-source traits from biome_parser; do not copy an old trait implementation from a skill or issue.
- Use checked byte and character accessors supplied by the lexer infrastructure.
- Keep lexing context explicit where the same bytes have context-dependent meaning.
- Ensure every lexer path advances or returns EOF.
- Use
&strlexer tests for valid multibyte characters and character-boundary/index behavior. Test malformed byte sequences only through an existing byte-oriented API.
Testing
Load testing-codegen for parser quick tests and snapshot mechanics.
- Use the crate's
quick_testto inspect a CST while developing. - Add persistent fixtures under the parser crate's current
ok/anderror/directories. - A parser bug fix needs the smallest fixture that failed before the change.
- Recovery changes need malformed input followed by valid syntax to prove parsing resumes correctly.
Review Checklist
Absentpaths consume no input.- Required nodes and tokens produce useful diagnostics.
- Recovery emits a grammar-valid bogus node.
- Every loop either advances or exits.
- List recovery stops before the enclosing boundary.
- The CST retains all source text, including malformed input.
- Grammar changes include generated syntax and factory artifacts.
- Valid and malformed fixtures exercise the changed path.
References
- Parser guide:
crates/biome_parser/CONTRIBUTING.md - Grammars:
xtask/codegen/*.ungram - Parser infrastructure:
crates/biome_parser/src/ - Language implementations:
crates/biome_*_parser/src/
© biomejs, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in .agents/skills/parser-development of biomejs/biome.
Open the folder on GitHubat commit c870caa
Compare with similar skills
Parser Development next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Parser Development this skillbiomejs/biome | 26k | — | ~1.2k | Automated safety check: Pass | Apache-2.0 | |
| Install Anti-Slop Oxlint Rulesdmmulroy/anti-slop | 5.3k | 1 repos | ~2.2k | Automated safety check: Pass | MIT | |
| Summarise Ecosystem Resultsastral-sh/ruff | 50k | 1 repos | ~2.2k | Automated safety check: Pass | MIT | |
| Minimizing Ty Ecosystem Changesastral-sh/ruff | 50k | — | ~4.6k | Automated safety check: Pass | MIT | |
| Babysit PR To Pass CIsgl-project/sglang | 37k | 2 repos | ~3k | Automated safety check: Pass | Apache-2.0 | |
| Rust Best Practicesfarm-fe/farm | 5.6k | 3 repos | ~1.1k | Automated safety check: Pass | MIT |
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Categories
Questions about Parser Development
What does Parser Development do?
A skill your agent uses when implementing or modifying Biome parser behavior, including .ungram grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures. Parser Development is an agent skill from biomejs/biome, published by the product's own GitHub organization.ungram grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures.
When should I use Parser Development?
Parser Development fits situations like: modifying Biome parser behavior; including .ungram grammars; separated lists; parser fixtures.
How do I install Parser Development in Claude Code?
Run `npx skills add biomejs/biome --skill parser-development -a claude-code`. Or copy the skill folder (.agents/skills/parser-development in biomejs/biome) into .claude/skills/parser-development in your project. Claude Code loads it when a task matches its description.
How do I install Parser Development in Codex?
Run `npx skills add biomejs/biome --skill parser-development -a codex`. Or copy the skill folder (.agents/skills/parser-development in biomejs/biome) into .agents/skills/parser-development in your project. Codex loads it when a task matches its description.
Can I use Parser Development in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add biomejs/biome --skill parser-development -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/parser-development, .gemini/skills/parser-development, .github/skills/parser-development and .opencode/skills/parser-development in your project.
What does Parser Development need to run?
Going by SKILL.md and its folder, Parser Development needs the command-line tools its instructions call (just). Compatibility (from SKILL.md): Designed for coding agents working on the Biome codebase (github.com/biomejs/biome)..
Does Parser Development access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Parser Development safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Parser Development use?
Parser Development is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Parser Development use?
About 1.2k tokens (SKILL.md is roughly 4.6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Parser Development?
Skills that share tags, products or a category with Parser Development: Install Anti-Slop Oxlint Rules (dmmulroy/anti-slop, 5.3k stars), Summarise Ecosystem Results (astral-sh/ruff, 50k stars), Minimizing Ty Ecosystem Changes (astral-sh/ruff, 50k stars) and Babysit PR To Pass CI (sgl-project/sglang, 37k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Parser Development?
biomejs (a GitHub organization, an official publisher) maintains it in biomejs/biome, which has 25,910 GitHub stars. The repository holds 12 skills in this directory. The repository was last updated on October 8, 2026.
Source: biomejs/biome on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.