configure-formatting

/configure:formatting

Check and configure code formatting tools against modern best practices.

When to Use This Skill

Use this skill when...	Use another approach when...
Setting up Biome, Prettier, Ruff format, or rustfmt for a project	Running an existing formatter (biome format, ruff format)
Migrating from Prettier to Biome or Black to Ruff	Fixing individual formatting issues in specific files
Auditing formatter configuration for completeness and best practices	Configuring linting rules (/configure:linting instead)
Adding format-on-save and CI format checks	Setting up pre-commit hooks only (/configure:pre-commit instead)
Standardizing formatting settings across a monorepo	Editing .editorconfig or .vscode/settings.json manually

Context

• Biome config: !find . -maxdepth 1 -name \'biome.json\'
• Prettier config: !find . -maxdepth 1 \( -name '.prettierrc*' -o -name 'prettier.config.*' \)
• Ruff config: !grep -l 'tool.ruff.format' pyproject.toml
• Black config: !grep -l 'tool.black' pyproject.toml
• Rustfmt config: !find . -maxdepth 1 \( -name 'rustfmt.toml' -o -name '.rustfmt.toml' \)
• EditorConfig: !find . -maxdepth 1 -name \'.editorconfig\'
• Package JSON: !find . -maxdepth 1 -name \'package.json\'
• Python project: !find . -maxdepth 1 -name \'pyproject.toml\'
• Rust project: !find . -maxdepth 1 -name \'Cargo.toml\'
• Pre-commit: !find . -maxdepth 1 -name \'.pre-commit-config.yaml\'
• Project standards: !find . -maxdepth 1 -name \'.project-standards.yaml\'

Parameters

Parse from $ARGUMENTS:

• --check-only: Report compliance status without modifications
• --fix: Apply all fixes automatically without prompting
• --formatter <formatter>: Override formatter detection (biome, prettier, ruff, rustfmt)

Version Checking

CRITICAL: Before flagging outdated formatters, verify latest releases using WebSearch or WebFetch:

1. Biome: Check biomejs.dev or GitHub releases
2. Prettier: Check prettier.io or npm
3. Ruff: Check docs.astral.sh/ruff or GitHub releases
4. rustfmt: Bundled with Rust toolchain - check Rust releases

Execution

Execute this code formatting configuration workflow:

Step 1: Detect project languages and existing formatters

Check for language indicators and formatter configurations:

Indicator	Language	Detected Formatter
biome.json with formatter	JavaScript/TypeScript	Biome
.prettierrc.*	JavaScript/TypeScript	Prettier
pyproject.toml [tool.ruff.format]	Python	Ruff
pyproject.toml [tool.black]	Python	Black (legacy)
rustfmt.toml or .rustfmt.toml	Rust	rustfmt

Modern formatting preferences:

• JavaScript/TypeScript: Biome (preferred) or Prettier
• Python: Ruff format (replaces Black)
• Rust: rustfmt (standard)

Step 2: Analyze current formatter configuration

For each detected formatter, check configuration completeness:

1. Config file exists with required settings (indent, line width, quotes, etc.)
2. Ignore patterns configured
3. Format scripts defined in package.json / pyproject.toml
4. Pre-commit hook configured
5. CI/CD check configured

Step 3: Generate compliance report

Print a formatted compliance report:

Code Formatting Compliance Report
==================================
Project: [name]
Language: [detected]
Formatter: [detected]

Configuration:  [status per check]
Format Options: [status per check]
Scripts:        [status per check]
Integration:    [status per check]

Overall: [X issues found]
Recommendations: [list specific fixes]

If --check-only, stop here.

Step 4: Install and configure formatter (if --fix or user confirms)

Based on detected language and formatter preference, install and configure. Use configuration templates from REFERENCE.md.

1. Install formatter package
2. Create configuration file (biome.json, .prettierrc.json, pyproject.toml section, rustfmt.toml)
3. Add format scripts to package.json or Makefile/justfile
4. Create ignore file if needed (.prettierignore)

Step 5: Create EditorConfig integration

Create or update .editorconfig with settings matching the formatter configuration.

Step 6: Handle migrations (if applicable)

If legacy formatter detected (Prettier -> Biome, Black -> Ruff):

1. Import existing configuration
2. Install new formatter
3. Remove old formatter
4. Update scripts
5. Update pre-commit hooks

Use migration guides from REFERENCE.md.

Step 7: Configure pre-commit hooks

Add formatter to .pre-commit-config.yaml using the appropriate hook repository.

Step 8: Configure CI/CD integration

Add format check step to GitHub Actions workflow.

Step 9: Configure editor integration

Create or update .vscode/settings.json with format-on-save and .vscode/extensions.json with formatter extension.

Step 10: Update standards tracking

Update .project-standards.yaml:

components:
  formatting: "2025.1"
  formatting_tool: "[biome|prettier|ruff|rustfmt]"
  formatting_pre_commit: true
  formatting_ci: true

Step 11: Print completion report

Print a summary of changes made, scripts added, and next steps (run format, verify CI, enable format-on-save).

For detailed configuration templates, migration guides, and pre-commit configurations, see REFERENCE.md.

Agentic Optimizations

Context	Command
Quick compliance check	/configure:formatting --check-only
Auto-fix all issues	/configure:formatting --fix
Check Biome formatting	biome format --check --reporter=github
Check Prettier formatting	`npx prettier --check . 2>&1
Check Ruff formatting	ruff format --check --output-format=github
Check rustfmt formatting	`cargo fmt --check 2>&1

Flags

Flag	Description
--check-only	Report status without offering fixes
--fix	Apply all fixes automatically without prompting
--formatter <formatter>	Override formatter detection (biome, prettier, ruff, rustfmt)

Examples

# Check compliance and offer fixes
/configure:formatting

# Check only, no modifications
/configure:formatting --check-only

# Auto-fix and migrate to Biome
/configure:formatting --fix --formatter biome

Error Handling

• Multiple formatters detected: Warn about conflict, suggest migration
• No package manager found: Cannot install formatter, error
• Invalid configuration: Report parse error, offer to replace with template
• Formatting conflicts: Report files that would be reformatted

See Also

• /configure:linting - Configure linting tools
• /configure:editor - Configure editor settings
• /configure:pre-commit - Pre-commit hook configuration
• /configure:all - Run all compliance checks
• Biome documentation: https://biomejs.dev
• Ruff documentation: https://docs.astral.sh/ruff
• rustfmt documentation: https://rust-lang.github.io/rustfmt