/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, Ruff format, or rustfmt for a project | Running an existing formatter (biome format, ruff format) | | Migrating from Prettier or ESLint 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: !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CRITICAL: Before flagging outdated formatters, verify latest releases using WebSearch or WebFetch:

Biome: Check biomejs.dev or GitHub releases
Ruff: Check docs.astral.sh/ruff or GitHub releases
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:

| Signal | CI_FORMAT | Why | |--------|-------------|-----| | Workflow runs biome check / biome ci | true | In Biome 2.x check is the combined command (formatter + linter + import sorting); ci is its CI-oriented variant | | Workflow runs biome format, ruff format, cargo fmt, prettier | true | Format-only commands, named directly | | Workflow runs biome lint | false | Lint-only — it does not format | | Workflow runs bun run <s> / npm run <s> / pnpm run <s> / yarn <s> and package.json's scripts.<s> contains any command above | true | The idiomatic setup keeps the real command in package.json | | That script calls another script (depth 2+) | false | Exactly one level is resolved; deeper chains are out of scope |

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.

Install formatter package
Create configuration file (biome.json, pyproject.toml section, rustfmt.toml)
Add format scripts to package.json or Makefile/justfile
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):

Import existing configuration
Install new formatter
Remove old formatter
Update scripts
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

| 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 Ruff formatting | ruff format --check --output-format=github | | Check rustfmt formatting | cargo fmt --check 2>&1 | head -20 |

Flags

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