/configure:formatting

Check and configure code formatting tools against modern best practices.

Context

This command validates code formatting configuration and upgrades to modern tools.

Modern formatting preferences:

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

Version Checking

CRITICAL: Before flagging outdated formatters, verify latest releases:

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

Use WebSearch or WebFetch to verify current versions before reporting outdated formatters.

Workflow

Phase 1: Language Detection

Detect project language and existing formatters:

Phase 2: Current State Analysis

For each detected formatter, check configuration:

Biome (preferred for JS/TS):

• biome.json exists
• Formatter enabled
• Indent style configured
• Line width configured
• Quote style configured
• Files/ignore patterns set

Prettier:

• .prettierrc.* or prettier.config.* exists
• Print width configured
• Tab width configured
• Semicolons configured
• Quotes configured
• Trailing commas configured
• .prettierignore exists

Ruff Format (preferred for Python):

• pyproject.toml has [tool.ruff.format] section
• Quote style configured
• Indent style configured
• Line ending configured
• Docstring formatting configured

rustfmt:

• rustfmt.toml or .rustfmt.toml exists
• Edition configured
• Max width configured
• Tab spaces configured
• Newline style configured

Phase 3: Compliance Report

Generate formatted compliance report:

Code Formatting Compliance Report
==================================
Project: [name]
Language: [TypeScript | Python | Rust]
Formatter: [Biome 1.x | Ruff 0.x | rustfmt 1.x]

Configuration:
  Config file             biome.json                 [✅ EXISTS | ❌ MISSING]
  Formatter enabled       true                       [✅ ENABLED | ❌ DISABLED]
  Line width              100                        [✅ CONFIGURED | ⚠️ DEFAULT]
  Indent style            space                      [✅ CONFIGURED | ⚠️ DEFAULT]
  Indent width            2                          [✅ CONFIGURED | ⚠️ DEFAULT]
  Quote style             single                     [✅ CONFIGURED | ⚠️ DEFAULT]
  Ignore patterns         node_modules, dist         [✅ CONFIGURED | ⚠️ INCOMPLETE]

Format Options:
  Semicolons              always                     [✅ CONFIGURED | ⚠️ DEFAULT]
  Trailing commas         all                        [✅ CONFIGURED | ⚠️ DEFAULT]
  Arrow parens            always                     [✅ CONFIGURED | ⏭️ N/A]
  End of line             lf                         [✅ CONFIGURED | ⚠️ DEFAULT]

Scripts:
  format command          package.json scripts       [✅ CONFIGURED | ❌ MISSING]
  format:check            package.json scripts       [✅ CONFIGURED | ❌ MISSING]

Integration:
  Pre-commit hook         .pre-commit-config.yaml    [✅ CONFIGURED | ❌ MISSING]
  CI/CD check             .github/workflows/         [✅ CONFIGURED | ❌ MISSING]
  Editor config           .editorconfig              [✅ CONFIGURED | ⚠️ MISSING]

Overall: [X issues found]

Recommendations:
  - Migrate from Prettier to Biome for better performance
  - Add .editorconfig for editor consistency
  - Enable format-on-save in editor

Phase 4: Configuration (if –fix or user confirms)

Biome Configuration (Recommended for JS/TS)

Install Biome:

npm install --save-dev @biomejs/biome
# or
bun add --dev @biomejs/biome

Create biome.json:

{
  "$schema": "https://biomejs.dev/schemas/1.9.4/schema.json",
  "formatter": {
    "enabled": true,
    "formatWithErrors": false,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100,
    "lineEnding": "lf"
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "semicolons": "always",
      "trailingCommas": "all",
      "arrowParentheses": "always",
      "bracketSpacing": true,
      "jsxQuoteStyle": "double"
    }
  },
  "json": {
    "formatter": {
      "enabled": true,
      "indentWidth": 2
    }
  },
  "files": {
    "include": ["src/**/*.ts", "src/**/*.tsx", "src/**/*.js", "src/**/*.jsx", "*.json"],
    "ignore": [
      "node_modules",
      "dist",
      "build",
      ".next",
      "coverage",
      "*.min.js"
    ]
  }
}

Add npm scripts to package.json:

{
  "scripts": {
    "format": "biome format --write .",
    "format:check": "biome format .",
    "lint:format": "biome check --write ."
  }
}

Prettier Configuration (Alternative)

Install Prettier:

npm install --save-dev prettier
# or
bun add --dev prettier

Create .prettierrc.json:

{
  "printWidth": 100,
  "tabWidth": 2,
  "useTabs": false,
  "semi": true,
  "singleQuote": true,
  "quoteProps": "as-needed",
  "jsxSingleQuote": false,
  "trailingComma": "all",
  "bracketSpacing": true,
  "bracketSameLine": false,
  "arrowParens": "always",
  "endOfLine": "lf",
  "embeddedLanguageFormatting": "auto"
}

Create .prettierignore:

node_modules
dist
build
.next
coverage
*.min.js
*.min.css
package-lock.json
pnpm-lock.yaml

Add npm scripts to package.json:

{
  "scripts": {
    "format": "prettier --write .",
    "format:check": "prettier --check ."
  }
}

Ruff Format Configuration (Recommended for Python)

Install Ruff:

uv add --group dev ruff

Update pyproject.toml:

[tool.ruff.format]
# Quote style (double or single)
quote-style = "double"

# Indent style (space or tab)
indent-style = "space"

# Line ending (auto, lf, crlf, cr)
line-ending = "auto"

# Skip magic trailing comma
skip-magic-trailing-comma = false

# Docstring formatting
docstring-code-format = true
docstring-code-line-length = 72

# Preview mode for unreleased formatting features
preview = false

[tool.ruff]
# Line length for both linter and formatter
line-length = 100

# Exclude directories
exclude = [
    ".git",
    ".venv",
    "__pycache__",
    "dist",
    "build",
]

Run Ruff format:

uv run ruff format .

Black Configuration (Alternative)

Install Black:

uv add --group dev black

Update pyproject.toml:

[tool.black]
line-length = 100
target-version = ['py312']
include = '\.pyi?$'
extend-exclude = '''
/(
  # directories
  \.eggs
  | \.git
  | \.venv
  | dist
  | build
)/
'''

rustfmt Configuration (Rust)

Create rustfmt.toml:

# Edition
edition = "2021"

# Max line width
max_width = 100

# Tab spaces
tab_spaces = 4

# Hard tabs
hard_tabs = false

# Newline style (Unix, Windows, Native)
newline_style = "Unix"

# Use small heuristics
use_small_heuristics = "Default"

# Reorder imports
reorder_imports = true

# Reorder modules
reorder_modules = true

# Remove nested parens
remove_nested_parens = true

# Format code in doc comments
format_code_in_doc_comments = true

# Normalize comments
normalize_comments = true

# Wrap comments
wrap_comments = true

# Format strings
format_strings = true

# Format macro bodies
format_macro_bodies = true

# Format macro matchers
format_macro_matchers = true

# Imports granularity (Preserve, Crate, Module, Item, One)
imports_granularity = "Crate"

# Group imports (Preserve, StdExternalCrate)
group_imports = "StdExternalCrate"

Run rustfmt:

cargo fmt --all

Phase 5: EditorConfig Integration

Create .editorconfig:

# EditorConfig is awesome: https://EditorConfig.org

# top-most EditorConfig file
root = true

# Unix-style newlines with a newline ending every file
[*]
charset = utf-8
end_of_line = lf
insert_final_newline = true
trim_trailing_whitespace = true

# JavaScript, TypeScript, JSON
[*.{js,jsx,ts,tsx,json,jsonc}]
indent_style = space
indent_size = 2
max_line_length = 100

# Python
[*.py]
indent_style = space
indent_size = 4
max_line_length = 100

# Rust
[*.rs]
indent_style = space
indent_size = 4
max_line_length = 100

# YAML
[*.{yml,yaml}]
indent_style = space
indent_size = 2

# Markdown
[*.md]
trim_trailing_whitespace = false
max_line_length = off

# Makefile
[Makefile]
indent_style = tab

Phase 6: Migration Guides

Prettier → Biome Migration

Step 1: Install Biome

npm install --save-dev @biomejs/biome

Step 2: Import Prettier config

npx @biomejs/biome migrate prettier --write

Step 3: Review and adjust biome.json

Step 4: Remove Prettier

npm uninstall prettier
rm .prettierrc.* prettier.config.* .prettierignore

Step 5: Update scripts

{
  "scripts": {
    "format": "biome format --write .",
    "format:check": "biome format ."
  }
}

Black → Ruff Format Migration

Step 1: Install Ruff

uv add --group dev ruff

Step 2: Configure in pyproject.toml (see Phase 4)

Step 3: Format codebase

uv run ruff format .

Step 4: Remove Black

uv remove black

Step 5: Update pre-commit hooks

repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.4
    hooks:
      - id: ruff-format

Phase 7: Pre-commit Integration

Biome:

repos:
  - repo: https://github.com/biomejs/pre-commit
    rev: v0.4.0
    hooks:
      - id: biome-check
        additional_dependencies: ["@biomejs/biome@1.9.4"]

Prettier:

repos:
  - repo: https://github.com/pre-commit/mirrors-prettier
    rev: v4.0.0-alpha.8
    hooks:
      - id: prettier
        types_or: [javascript, jsx, ts, tsx, json, yaml, markdown]

Ruff Format:

repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.4
    hooks:
      - id: ruff-format

rustfmt:

repos:
  - repo: https://github.com/doublify/pre-commit-rust
    rev: v1.0
    hooks:
      - id: fmt

Phase 8: CI/CD Integration

GitHub Actions – Biome:

- name: Check formatting
  run: npx @biomejs/biome format .

GitHub Actions – Prettier:

- name: Check formatting
  run: npm run format:check

GitHub Actions – Ruff:

- name: Check formatting
  run: uv run ruff format --check .

GitHub Actions – rustfmt:

- name: Check formatting
  run: cargo fmt --all -- --check

Phase 9: Editor Integration

VS Code Settings

Create .vscode/settings.json:

{
  "editor.formatOnSave": true,
  "editor.defaultFormatter": "biomejs.biome",
  "[javascript]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[typescript]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[python]": {
    "editor.defaultFormatter": "charliermarsh.ruff"
  },
  "[rust]": {
    "editor.defaultFormatter": "rust-lang.rust-analyzer",
    "editor.formatOnSave": true
  }
}

Create .vscode/extensions.json:

{
  "recommendations": [
    "biomejs.biome",
    "charliermarsh.ruff",
    "rust-lang.rust-analyzer",
    "editorconfig.editorconfig"
  ]
}

Phase 10: Standards Tracking

Update .project-standards.yaml:

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

Phase 11: Updated Compliance Report

Code Formatting Configuration Complete
=======================================

Language: TypeScript
Formatter: Biome 1.9.4 (modern, fast)

Configuration Applied:
  ✅ biome.json created
  ✅ Formatter enabled
  ✅ Line width: 100
  ✅ Indent: 2 spaces
  ✅ Quotes: single
  ✅ Semicolons: always
  ✅ Trailing commas: all
  ✅ Ignore patterns configured

Scripts Added:
  ✅ npm run format (format all)
  ✅ npm run format:check (check only)

Integration:
  ✅ .editorconfig created
  ✅ Pre-commit hook configured
  ✅ CI/CD check added
  ✅ VS Code settings configured

Migration:
  ✅ Prettier removed
  ✅ Configuration imported

Next Steps:
  1. Format codebase:
     npm run format

  2. Verify formatting:
     npm run format:check

  3. Enable format-on-save in editor:
     Install Biome extension

  4. Verify CI integration:
     Push changes and check workflow

Documentation: docs/FORMATTING.md

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