Add Husky + lint-staged + ESLint with CI enforcement

[Copilot]

Adds pre-commit hooks and CI checks to enforce consistent formatting and linting across platforms, normalizing to LF line endings.

Changes

• package.json: Added lint and prepare scripts, moved prettier to devDependencies, added lint-staged config with ESLint caching
• eslint.config.js: ESLint 9 flat config extending eslint:recommended and prettier, with browser/Node/test globals
• .husky/pre-commit: Runs lint-staged on staged files only
• .github/workflows/ci-format-lint.yml: Checks format and lint on PR/push to all branches using ubuntu-24.04 runner (matching existing CI workflow)
• .editorconfig: Enforces LF, UTF-8, 2-space indents across editors
• .gitignore: Added .eslintcache

Note: .prettierrc.json and .gitattributes (LF enforcement) already existed with correct configuration.

Example

Pre-commit hook automatically formats and lints:

git commit -m "fix: update source"
# → lint-staged runs prettier --write and eslint --fix on staged files
# → commit proceeds with formatted code

CI workflow validates on push:

- name: Prettier check
  run: npm run format-check
- name: ESLint
  run: npm run lint

This pull request was created as a result of the following prompt from Copilot chat.

Goal
Add reliable, cross-platform formatting and linting enforcement to AR.js-core using Husky + lint-staged locally and a CI workflow that runs Prettier and ESLint on every PR/push. Normalize line endings to LF across platforms to avoid Windows vs Linux divergences. Keep existing scripts and builds intact.

Scope of changes

1. package.json

• Add scripts: "format", "format-check", "lint", and "prepare": "husky" (preserve existing scripts).
• Add devDependencies: eslint, eslint-config-prettier, husky, lint-staged, prettier.
• Move prettier from dependencies to devDependencies if currently listed under dependencies (to avoid shipping it at runtime).
• Add lint-staged config: format staged files with Prettier and fix JS/TS with ESLint.

2. Prettier configuration

• Add .prettierrc.json with endOfLine: "lf" and standard style options.

3. Editor/line-endings normalization

• Add .editorconfig to align IDE defaults across contributors.
• Add .gitattributes to enforce LF on text files and keep binaries untouched.

4. Git hooks

• Add .husky/pre-commit that runs lint-staged (fast, staged-only checks).

5. ESLint config

• Add a minimal .eslintrc.json extending eslint:recommended and prettier (to avoid rule conflicts with Prettier). No opinionated rules beyond recommended.

6. CI workflow

• Add .github/workflows/ci-format-lint.yml to run on pull_request and push (main, dev, and copilot/** branches). Steps: setup Node 20, npm ci, run format-check and lint.

Non-goals

• Do not modify existing build, test, or example code other than formatting if required by Prettier.
• Do not change webpack/vite configs.

Files to add/update

{
  "scripts": {
    "format": "prettier --write .",
    "format-check": "prettier --check .",
    "lint": "eslint .",
    "prepare": "husky"
  },
  "devDependencies": {
    "eslint": "^9.14.0",
    "eslint-config-prettier": "^9.1.0",
    "husky": "^9.1.7",
    "lint-staged": "15.4.3",
    "prettier": "^3.4.2"
  },
  "lint-staged": {
    "*.{js,jsx,ts,tsx,css,md,json}": [
      "prettier --write"
    ],
    "*.{js,jsx,ts,tsx}": [
      "eslint --fix"
    ]
  }
}

{
  "printWidth": 100,
  "singleQuote": true,
  "trailingComma": "all",
  "semi": true,
  "arrowParens": "always",
  "endOfLine": "lf"
}

root = true

[*]
end_of_line = lf
insert_final_newline = true
charset = utf-8
indent_style = space
indent_size = 2

# Enforce LF on text files
*.js text eol=lf
*.mjs text eol=lf
*.cjs text eol=lf
*.ts text eol=lf
*.json text eol=lf
*.md text eol=lf
*.css text eol=lf
*.html text eol=lf

# Binary files untouched
*.png binary
*.jpg binary
*.jpeg binary
*.gif binary
*.webp binary
*.mp4 binary
*.mp3 binary
*.woff binary
*.woff2 binary
*.ttf binary
*.otf binary

#!/usr/bin/env sh
. "$(dirname -- "$0")/_/husky.sh"

# Only format and lint what's staged (fast)
npx lint-staged

{
  "root": true,
  "env": {
    "browser": true,
    "es2022": true,
    "node": true
  },
  "extends": [
    "eslint:recommended",
    "prettier"
  ],
  "parserOptions": {
    "ecmaVersion": 2022,
    "sourceType": "module"
  },
  "rules": {}
}

name: Format and Lint

on:
  pull_request:
  push:
    branches: [main, dev, "copilot/**"]

jobs:
  format-lint:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Use Node
        uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm

      - name: Install
        run: npm ci

      - name: Prettier check
        run: npm run format-check

      - name: ESLint
        run: npm run lint

Notes

• When updating package.json, preserve existing fields and scripts (dev, build, test, vite scripts, etc.). Only add the new scripts/sections or merge if keys already exist.
• If prettier currently appears under dependencies, move it to devDependencies. Keep versions as defined above unless a newer compatible version is already present.
• Ensure executable flag for .husky/pre-commit (chmod +x) after creation in the repo; Husky usually handles this when committed in Git.
• CI workflow is additive and should not replace existing workflows.

Original prompt

Goal
Add reliable, cross-platform formatting and linting enforcement to AR.js-core using Husky + lint-staged locally and a CI workflow that runs Prettier and ESLint on every PR/push. Normalize line endings to LF across platforms to avoid Windows vs Linux divergences. Keep existing scripts and builds intact.

Scope of changes

1. package.json

• Add scripts: "format", "format-check", "lint", and "prepare": "husky" (preserve existing scripts).
• Add devDependencies: eslint, eslint-config-prettier, husky, lint-staged, prettier.
• Move prettier from dependencies to devDependencies if currently listed under dependencies (to avoid shipping it at runtime).
• Add lint-staged config: format staged files with Prettier and fix JS/TS with ESLint.

2. Prettier configuration

• Add .prettierrc.json with endOfLine: "lf" and standard style options.

3. Editor/line-endings normalization

• Add .editorconfig to align IDE defaults across contributors.
• Add .gitattributes to enforce LF on text files and keep binaries untouched.

4. Git hooks

• Add .husky/pre-commit that runs lint-staged (fast, staged-only checks).

5. ESLint config

• Add a minimal .eslintrc.json extending eslint:recommended and prettier (to avoid rule conflicts with Prettier). No opinionated rules beyond recommended.

6. CI workflow

• Add .github/workflows/ci-format-lint.yml to run on pull_request and push (main, dev, and copilot/** branches). Steps: setup Node 20, npm ci, run format-check and lint.

Non-goals

• Do not modify existing build, test, or example code other than formatting if required by Prettier.
• Do not change webpack/vite configs.

Files to add/update

{
  "scripts": {
    "format": "prettier --write .",
    "format-check": "prettier --check .",
    "lint": "eslint .",
    "prepare": "husky"
  },
  "devDependencies": {
    "eslint": "^9.14.0",
    "eslint-config-prettier": "^9.1.0",
    "husky": "^9.1.7",
    "lint-staged": "15.4.3",
    "prettier": "^3.4.2"
  },
  "lint-staged": {
    "*.{js,jsx,ts,tsx,css,md,json}": [
      "prettier --write"
    ],
    "*.{js,jsx,ts,tsx}": [
      "eslint --fix"
    ]
  }
}

{
  "printWidth": 100,
  "singleQuote": true,
  "trailingComma": "all",
  "semi": true,
  "arrowParens": "always",
  "endOfLine": "lf"
}

root = true

[*]
end_of_line = lf
insert_final_newline = true
charset = utf-8
indent_style = space
indent_size = 2

# Enforce LF on text files
*.js text eol=lf
*.mjs text eol=lf
*.cjs text eol=lf
*.ts text eol=lf
*.json text eol=lf
*.md text eol=lf
*.css text eol=lf
*.html text eol=lf

# Binary files untouched
*.png binary
*.jpg binary
*.jpeg binary
*.gif binary
*.webp binary
*.mp4 binary
*.mp3 binary
*.woff binary
*.woff2 binary
*.ttf binary
*.otf binary

#!/usr/bin/env sh
. "$(dirname -- "$0")/_/husky.sh"

# Only format and lint what’s staged (fast)
npx lint-staged

{
  "root": true,
  "env": {
    "browser": true,
    "es2022": true,
    "node": true
  },
  "extends": [
    "eslint:recommended",
    "prettier"
  ],
  "parserOptions": {
    "ecmaVersion": 2022,
    "sourceType": "module"
  },
  "rules": {}
}

name: Format and Lint

on:
  pull_request:
  push:
    branches: [main, dev, "copilot/**"]

jobs:
  format-lint:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Use Node
        uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm

      - name: Install
        run: npm ci

      - name: Prettier check
        run: npm run format-check

      - name: ESLint
        run: npm run lint

Notes

• When updating package.json, preserve existing fields and scripts (dev, build, test, vite scripts, etc.). Only add the new scripts/sections or merge if keys already exist.
• If prettier currently appears under dependencies, move it to devDependencies. Keep versions as defined above unless a newer compatible version is already present.
• Ensure executable flag for .husky/pre-commit (chmod +x) after creation in the repo; Husky usually handles this when committed in Git.
• CI workflow is additive and should not replace existing workflows.

This pull request was created as a result of the following prompt from Copilot chat.

Goal
Add reliable, cross-platform formatting and linting enforcement to AR.js-core using Husky + lint-staged locally and a CI workflow that runs Prettier and ESLint on every PR/push. Normalize line endings to LF across platforms to avoid Windows vs Linux divergences. Keep existing scripts and builds intact.

Scope of changes

1. package.json

• Add scripts: "format", "format-check", "lint", and "prepare": "husky" (preserve existing scripts).
• Add devDependencies: eslint, eslint-config-prettier, husky, lint-staged, prettier.
• Move prettier from dependencies to devDependencies if currently listed under dependencies (to avoid shipping it at runtime).
• Add lint-staged config: format staged files with Prettier and fix JS/TS with ESLint.

2. Prettier configuration

• Add .prettierrc.json with endOfLine: "lf" and standard style options.

3. Editor/line-endings normalization

• Add .editorconfig to align IDE defaults across contributors.
• Add .gitattributes to enforce LF on text files and keep binaries untouched.

4. Git hooks

• Add .husky/pre-commit that runs lint-staged (fast, staged-only checks).

5. ESLint config

• Add a minimal .eslintrc.json extending eslint:recommended and prettier (to avoid rule conflicts with Prettier). No opinionated rules beyond recommended.

6. CI workflow

• Add .github/workflows/ci-format-lint.yml to run on pull_request and push (main, dev, and copilot/** branches). Steps: setup Node 20, npm ci, run format-check and lint.

Non-goals

• Do not modify existing build, test, or example code other than formatting if required by Prettier.
• Do not change webpack/vite configs.

Files to add/update

{
  "scripts": {
    "format": "prettier --write .",
    "format-check": "prettier --check .",
    "lint": "eslint .",
    "prepare": "husky"
  },
  "devDependencies": {
    "eslint": "^9.14.0",
    "eslint-config-prettier": "^9.1.0",
    "husky": "^9.1.7",
    "lint-staged": "15.4.3",
    "prettier": "^3.4.2"
  },
  "lint-staged": {
    "*.{js,jsx,ts,tsx,css,md,json}": [
      "prettier --write"
    ],
    "*.{js,jsx,ts,tsx}": [
      "eslint --fix"
    ]
  }
}

{
  "printWidth": 100,
  "singleQuote": true,
  "trailingComma": "all",
  "semi": true,
  "arrowParens": "always",
  "endOfLine": "lf"
}

root = true

[*]
end_of_line = lf
insert_final_newline = true
charset = utf-8
indent_style = space
indent_size = 2

# Enforce LF on text files
*.js text eol=lf
*.mjs text eol=lf
*.cjs text eol=lf
*.ts text eol=lf
*.json text eol=lf
*.md text eol=lf
*.css text eol=lf
*.html text eol=lf

# Binary files untouched
*.png binary
*.jpg binary
*.jpeg binary
*.gif binary
*.webp binary
*.mp4 binary
*.mp3 binary
*.woff binary
*.woff2 binary
*.ttf binary
*.otf binary

#!/usr/bin/env sh
. "$(dirname -- "$0")/_/husky.sh"

# Only format and lint what’s staged (fast)
npx lint-staged

{
  "root": true,
  "env": {
    "browser": true,
    "es2022": true,
    "node": true
  },
  "extends": [
    "eslint:recommended",
    "prettier"
  ],
  "parserOptions": {
    "ecmaVersion": 2022,
    "sourceType": "module"
  },
  "rules": {}
}

name: Format and Lint

on:
  pull_request:
  push:
    branches: [main, dev, "copilot/**"]

jobs:
  format-lint:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Use Node
        uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm

      - name: Install
        run: npm ci

      - name: Prettier check
        run: npm run format-check

      - name: ESLint
        run: npm run lint

Notes

• When updating package.json, preserve existing fields and scripts (dev, build, test, vite scripts, etc.). Only add the new scripts/sections or merge if keys already exist.
• If prettier currently appears under dependencies, move it to devDependencies. Keep versions as defined above unless a newer compatible version is already present.
• Ensure executable flag for .husky/pre-commit (chmod +x) after creation in the repo; Husky usually handles this when committed in Git.
• CI workflow is additive and should not replace existing workflows.

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