Configure Formatting

/configure:formatting

Check and configure code formatting tools against modern best practices.

When to Use This Skill

Context

• Biome config: !find . -maxdepth 1 -name 'biome.json'
• Prettier config: !find . -maxdepth 1 \( -name '.prettierrc*' -o -name 'prettier.config.*' \)
• Ruff config: !find . -maxdepth 1 -name 'pyproject.toml' -exec grep -l 'tool.ruff.format' {} +
• Black config: !find . -maxdepth 1 -name 'pyproject.toml' -exec grep -l 'tool.black' {} +
• 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, 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CRITICAL: Before flagging outdated formatters, verify latest releases using WebSearch or WebFetch: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. Ruff: Check docs.astral.sh/ruff or GitHub releases
3. rustfmt: Bundled with Rust toolchain - check Rust releases

Execution

Execute this code formatting configuration workflow:

Step 1: Detect formatters and integration state

Run the detection script to scan the project for formatter config files, script/hook/CI presence, and a recommendation over the detected booleans:

bash "${CLAUDE_SKILL_DIR}/scripts/configure-formatting.sh" --home-dir "$HOME" --project-dir "$(pwd)"

Parse STATUS= and the ISSUES: block from the output. The KEY=VALUE lines report formatter detection (BIOME, PRETTIER, RUFF_FORMAT, BLACK, RUSTFMT, EDITORCONFIG), integration signals (FORMAT_SCRIPT, PRE_COMMIT_FORMAT, CI_FORMAT), and a RECOMMENDATION of configured (a modern formatter is set up), migrate (a legacy formatter wants migration to Biome/Ruff), or setup (no formatter detected).

How CI_FORMAT is decided. The probe scans .github/workflows/*.yml|yaml for a command that runs the formatter, then resolves one level of package-script indirection:

Indirection needs jq and a readable package.json. When package.json is absent, unparseable, or has no scripts key — or jq is unavailable — the lookup degrades silently to the direct-command scan (no stderr, exit 0).

Modern formatting preferences:

• JavaScript/TypeScript: Biome (replaces Prettier + ESLint). On RECOMMENDATION=migrate with Prettier present, offer migration to Biome — do not configure Prettier as the target formatter.
• Python: Ruff format (replaces Black)
• Rust: rustfmt (standard)

Step 2: 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 3: 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, pyproject.toml section, rustfmt.toml)
3. Add format scripts to package.json or Makefile/justfile
4. Configure ignore patterns in the formatter config (e.g. files.includes in biome.json)

Step 4: Create EditorConfig integration

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

Step 5: 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 6: Configure pre-commit hooks

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

Step 7: Configure CI/CD integration

Add format check step to GitHub Actions workflow.

Step 8: Configure editor integration

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

Step 9: Update standards tracking

Update .project-standards.yaml:

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

Step 10: 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

Flags

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