feat(wave3): add @mosaic/quality-rails — TypeScript code quality scaffolder

- Project detection: detectProjectKind (node/python/rust/unknown) - Scaffolder: writes ESLint/Biome/pre-commit configs based on profile - Embedded templates for strict/standard/minimal profiles - CLI: quality-rails init | check | doctor - Depends on @mosaic/types workspace:*
2026-03-06 20:21:57 -06:00
parent 8371783587
commit 494da37cb8
13 changed files with 882 additions and 0 deletions
--- a/packages/quality-rails/eslint.config.js
+++ b/packages/quality-rails/eslint.config.js
@@ -0,0 +1,20 @@
+import tsEslintPlugin from '@typescript-eslint/eslint-plugin';
+import tsEslintParser from '@typescript-eslint/parser';
+
+export default [
+  {
+    files: ['src/**/*.ts'],
+    languageOptions: {
+      parser: tsEslintParser,
+      sourceType: 'module',
+      ecmaVersion: 'latest',
+    },
+    plugins: {
+      '@typescript-eslint': tsEslintPlugin,
+    },
+    rules: {
+      'no-console': 'off',
+      '@typescript-eslint/no-explicit-any': 'off',
+    },
+  },
+];
--- a/packages/quality-rails/package.json
+++ b/packages/quality-rails/package.json
@@ -0,0 +1,30 @@
+{
+  "name": "@mosaic/quality-rails",
+  "version": "0.1.0",
+  "type": "module",
+  "description": "Mosaic quality rails - TypeScript code quality scaffolder",
+  "scripts": {
+    "build": "tsc -p tsconfig.json",
+    "typecheck": "tsc --noEmit",
+    "lint": "eslint src/",
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "@mosaic/types": "workspace:*",
+    "commander": "^13",
+    "js-yaml": "^4"
+  },
+  "devDependencies": {
+    "@types/node": "^22",
+    "@types/js-yaml": "^4",
+    "@typescript-eslint/eslint-plugin": "^8",
+    "@typescript-eslint/parser": "^8",
+    "eslint": "^9",
+    "typescript": "^5",
+    "vitest": "^2"
+  },
+  "publishConfig": {
+    "registry": "https://git.mosaicstack.dev/api/packages/mosaic/npm",
+    "access": "public"
+  }
+}
--- a/packages/quality-rails/src/cli.ts
+++ b/packages/quality-rails/src/cli.ts
@@ -0,0 +1,193 @@
+import { constants } from 'node:fs';
+import { access } from 'node:fs/promises';
+import { resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { Command } from 'commander';
+
+import { detectProjectKind } from './detect.js';
+import { scaffoldQualityRails } from './scaffolder.js';
+import type { ProjectKind, QualityProfile, RailsConfig } from './types.js';
+
+const VALID_PROFILES: readonly QualityProfile[] = ['strict', 'standard', 'minimal'];
+
+async function fileExists(filePath: string): Promise<boolean> {
+  try {
+    await access(filePath, constants.F_OK);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+function parseProfile(rawProfile: string): QualityProfile {
+  if (VALID_PROFILES.includes(rawProfile as QualityProfile)) {
+    return rawProfile as QualityProfile;
+  }
+  throw new Error(`Invalid profile: ${rawProfile}. Use one of ${VALID_PROFILES.join(', ')}.`);
+}
+
+function defaultLinters(kind: ProjectKind): string[] {
+  if (kind === 'node') {
+    return ['eslint', 'biome'];
+  }
+
+  if (kind === 'python') {
+    return ['ruff'];
+  }
+
+  if (kind === 'rust') {
+    return ['clippy'];
+  }
+
+  return [];
+}
+
+function defaultFormatters(kind: ProjectKind): string[] {
+  if (kind === 'node') {
+    return ['prettier'];
+  }
+
+  if (kind === 'python') {
+    return ['black'];
+  }
+
+  if (kind === 'rust') {
+    return ['rustfmt'];
+  }
+
+  return [];
+}
+
+function expectedFilesForKind(kind: ProjectKind): string[] {
+  if (kind === 'node') {
+    return ['.eslintrc', 'biome.json', '.githooks/pre-commit', 'PR-CHECKLIST.md'];
+  }
+
+  if (kind === 'python') {
+    return ['pyproject.toml', '.githooks/pre-commit', 'PR-CHECKLIST.md'];
+  }
+
+  if (kind === 'rust') {
+    return ['rustfmt.toml', '.githooks/pre-commit', 'PR-CHECKLIST.md'];
+  }
+
+  return ['.githooks/pre-commit', 'PR-CHECKLIST.md'];
+}
+
+function printScaffoldResult(config: RailsConfig, filesWritten: string[], warnings: string[], commandsToRun: string[]): void {
+  console.log(`[quality-rails] initialized at ${config.projectPath}`);
+  console.log(`kind=${config.kind} profile=${config.profile}`);
+
+  if (filesWritten.length > 0) {
+    console.log('files written:');
+    for (const filePath of filesWritten) {
+      console.log(`  - ${filePath}`);
+    }
+  }
+
+  if (commandsToRun.length > 0) {
+    console.log('run next:');
+    for (const command of commandsToRun) {
+      console.log(`  - ${command}`);
+    }
+  }
+
+  if (warnings.length > 0) {
+    console.log('warnings:');
+    for (const warning of warnings) {
+      console.log(`  - ${warning}`);
+    }
+  }
+}
+
+export function createQualityRailsCli(): Command {
+  const program = new Command('mosaic');
+  const qualityRails = program.command('quality-rails').description('Manage quality rails scaffolding');
+
+  qualityRails
+    .command('init')
+    .requiredOption('--project <path>', 'Project path')
+    .option('--profile <profile>', 'strict|standard|minimal', 'standard')
+    .action(async (options: { project: string; profile: string }) => {
+      const profile = parseProfile(options.profile);
+      const projectPath = resolve(options.project);
+      const kind = await detectProjectKind(projectPath);
+
+      const config: RailsConfig = {
+        projectPath,
+        kind,
+        profile,
+        linters: defaultLinters(kind),
+        formatters: defaultFormatters(kind),
+        hooks: true,
+      };
+
+      const result = await scaffoldQualityRails(config);
+      printScaffoldResult(config, result.filesWritten, result.warnings, result.commandsToRun);
+    });
+
+  qualityRails
+    .command('check')
+    .requiredOption('--project <path>', 'Project path')
+    .action(async (options: { project: string }) => {
+      const projectPath = resolve(options.project);
+      const kind = await detectProjectKind(projectPath);
+      const expected = expectedFilesForKind(kind);
+      const missing: string[] = [];
+
+      for (const relativePath of expected) {
+        const exists = await fileExists(resolve(projectPath, relativePath));
+        if (!exists) {
+          missing.push(relativePath);
+        }
+      }
+
+      if (missing.length > 0) {
+        console.error('[quality-rails] missing files:');
+        for (const relativePath of missing) {
+          console.error(`  - ${relativePath}`);
+        }
+        process.exitCode = 1;
+        return;
+      }
+
+      console.log(`[quality-rails] all expected files present for ${kind} project`);
+    });
+
+  qualityRails
+    .command('doctor')
+    .requiredOption('--project <path>', 'Project path')
+    .action(async (options: { project: string }) => {
+      const projectPath = resolve(options.project);
+      const kind = await detectProjectKind(projectPath);
+      const expected = expectedFilesForKind(kind);
+
+      console.log(`[quality-rails] doctor for ${projectPath}`);
+      console.log(`detected project kind: ${kind}`);
+
+      for (const relativePath of expected) {
+        const exists = await fileExists(resolve(projectPath, relativePath));
+        console.log(`  - ${exists ? 'ok' : 'missing'}: ${relativePath}`);
+      }
+
+      if (kind === 'unknown') {
+        console.log('recommendation: add package.json, pyproject.toml, or Cargo.toml for better defaults.');
+      }
+    });
+
+  return program;
+}
+
+export async function runQualityRailsCli(argv: string[] = process.argv): Promise<void> {
+  const program = createQualityRailsCli();
+  await program.parseAsync(argv);
+}
+
+const entryPath = process.argv[1] ? resolve(process.argv[1]) : '';
+if (entryPath.length > 0 && entryPath === fileURLToPath(import.meta.url)) {
+  runQualityRailsCli().catch((error: unknown) => {
+    console.error(error instanceof Error ? error.message : String(error));
+    process.exit(1);
+  });
+}
--- a/packages/quality-rails/src/detect.ts
+++ b/packages/quality-rails/src/detect.ts
@@ -0,0 +1,30 @@
+import { constants } from 'node:fs';
+import { access } from 'node:fs/promises';
+import { join } from 'node:path';
+
+import type { ProjectKind } from './types.js';
+
+async function fileExists(filePath: string): Promise<boolean> {
+  try {
+    await access(filePath, constants.F_OK);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export async function detectProjectKind(projectPath: string): Promise<ProjectKind> {
+  if (await fileExists(join(projectPath, 'package.json'))) {
+    return 'node';
+  }
+
+  if (await fileExists(join(projectPath, 'pyproject.toml'))) {
+    return 'python';
+  }
+
+  if (await fileExists(join(projectPath, 'Cargo.toml'))) {
+    return 'rust';
+  }
+
+  return 'unknown';
+}
--- a/packages/quality-rails/src/index.ts
+++ b/packages/quality-rails/src/index.ts
@@ -0,0 +1,5 @@
+export * from './cli.js';
+export * from './detect.js';
+export * from './scaffolder.js';
+export * from './templates.js';
+export * from './types.js';
--- a/packages/quality-rails/src/scaffolder.ts
+++ b/packages/quality-rails/src/scaffolder.ts
@@ -0,0 +1,201 @@
+import { spawn } from 'node:child_process';
+import { chmod, mkdir, readFile, writeFile } from 'node:fs/promises';
+import { dirname, join } from 'node:path';
+
+import {
+  biomeTemplate,
+  eslintTemplate,
+  prChecklistTemplate,
+  preCommitHookTemplate,
+  pyprojectSection,
+  rustfmtTemplate,
+} from './templates.js';
+import type { RailsConfig, ScaffoldResult } from './types.js';
+
+const PYPROJECT_START_MARKER = '# >>> mosaic-quality-rails >>>';
+const PYPROJECT_END_MARKER = '# <<< mosaic-quality-rails <<<';
+
+async function ensureDirectory(filePath: string): Promise<void> {
+  await mkdir(dirname(filePath), { recursive: true });
+}
+
+async function writeRelativeFile(
+  projectPath: string,
+  relativePath: string,
+  contents: string,
+  result: ScaffoldResult,
+): Promise<void> {
+  const absolutePath = join(projectPath, relativePath);
+  await ensureDirectory(absolutePath);
+  await writeFile(absolutePath, contents, { encoding: 'utf8', mode: 0o644 });
+  result.filesWritten.push(relativePath);
+}
+
+async function upsertPyproject(
+  projectPath: string,
+  profile: RailsConfig['profile'],
+  result: ScaffoldResult,
+): Promise<void> {
+  const pyprojectPath = join(projectPath, 'pyproject.toml');
+  const nextSection = pyprojectSection(profile);
+
+  let previous = '';
+  try {
+    previous = await readFile(pyprojectPath, 'utf8');
+  } catch {
+    previous = '';
+  }
+
+  const existingStart = previous.indexOf(PYPROJECT_START_MARKER);
+  const existingEnd = previous.indexOf(PYPROJECT_END_MARKER);
+
+  if (existingStart >= 0 && existingEnd > existingStart) {
+    const before = previous.slice(0, existingStart).trimEnd();
+    const after = previous.slice(existingEnd + PYPROJECT_END_MARKER.length).trimStart();
+    const rebuilt = [before, nextSection.trim(), after]
+      .filter((segment) => segment.length > 0)
+      .join('\n\n');
+    await writeRelativeFile(projectPath, 'pyproject.toml', `${rebuilt}\n`, result);
+    return;
+  }
+
+  const separator = previous.trim().length > 0 ? '\n\n' : '';
+  await writeRelativeFile(projectPath, 'pyproject.toml', `${previous.trimEnd()}${separator}${nextSection}`, result);
+}
+
+function runCommand(command: string, args: string[], cwd: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const child = spawn(command, args, {
+      cwd,
+      stdio: 'ignore',
+      env: process.env,
+    });
+
+    child.on('error', reject);
+    child.on('exit', (code) => {
+      if (code === 0) {
+        resolve();
+        return;
+      }
+      reject(new Error(`Command failed (${code ?? 'unknown'}): ${command} ${args.join(' ')}`));
+    });
+  });
+}
+
+function buildNodeDevDependencies(config: RailsConfig): string[] {
+  const dependencies = new Set<string>();
+
+  if (config.linters.some((linter) => linter.toLowerCase() === 'eslint')) {
+    dependencies.add('eslint');
+    dependencies.add('@typescript-eslint/parser');
+    dependencies.add('@typescript-eslint/eslint-plugin');
+  }
+
+  if (config.linters.some((linter) => linter.toLowerCase() === 'biome')) {
+    dependencies.add('@biomejs/biome');
+  }
+
+  if (config.formatters.some((formatter) => formatter.toLowerCase() === 'prettier')) {
+    dependencies.add('prettier');
+  }
+
+  if (config.hooks) {
+    dependencies.add('husky');
+  }
+
+  return [...dependencies];
+}
+
+async function installNodeDependencies(config: RailsConfig, result: ScaffoldResult): Promise<void> {
+  const dependencies = buildNodeDevDependencies(config);
+  if (dependencies.length === 0) {
+    return;
+  }
+
+  const commandLine = `pnpm add -D ${dependencies.join(' ')}`;
+
+  if (process.env.MOSAIC_QUALITY_RAILS_SKIP_INSTALL === '1') {
+    result.commandsToRun.push(commandLine);
+    return;
+  }
+
+  try {
+    await runCommand('pnpm', ['add', '-D', ...dependencies], config.projectPath);
+  } catch (error) {
+    result.warnings.push(
+      `Failed to auto-install Node dependencies: ${error instanceof Error ? error.message : String(error)}`,
+    );
+    result.commandsToRun.push(commandLine);
+  }
+}
+
+export async function scaffoldQualityRails(config: RailsConfig): Promise<ScaffoldResult> {
+  const result: ScaffoldResult = {
+    filesWritten: [],
+    commandsToRun: [],
+    warnings: [],
+  };
+
+  const normalizedLinters = new Set(config.linters.map((linter) => linter.toLowerCase()));
+
+  if (config.kind === 'node') {
+    if (normalizedLinters.has('eslint')) {
+      await writeRelativeFile(
+        config.projectPath,
+        '.eslintrc',
+        eslintTemplate(config.profile),
+        result,
+      );
+    }
+
+    if (normalizedLinters.has('biome')) {
+      await writeRelativeFile(
+        config.projectPath,
+        'biome.json',
+        biomeTemplate(config.profile),
+        result,
+      );
+    }
+
+    await installNodeDependencies(config, result);
+  }
+
+  if (config.kind === 'python') {
+    await upsertPyproject(config.projectPath, config.profile, result);
+  }
+
+  if (config.kind === 'rust') {
+    await writeRelativeFile(
+      config.projectPath,
+      'rustfmt.toml',
+      rustfmtTemplate(config.profile),
+      result,
+    );
+  }
+
+  if (config.hooks) {
+    await writeRelativeFile(
+      config.projectPath,
+      '.githooks/pre-commit',
+      preCommitHookTemplate(config),
+      result,
+    );
+    await chmod(join(config.projectPath, '.githooks/pre-commit'), 0o755);
+    result.commandsToRun.push('git config core.hooksPath .githooks');
+  }
+
+  await writeRelativeFile(
+    config.projectPath,
+    'PR-CHECKLIST.md',
+    prChecklistTemplate(config.profile),
+    result,
+  );
+
+  if (config.kind === 'unknown') {
+    result.warnings.push(
+      'Unable to detect project kind. Generated generic rails only (hooks + PR checklist).',
+    );
+  }
+
+  return result;
+}
--- a/packages/quality-rails/src/templates.ts
+++ b/packages/quality-rails/src/templates.ts
@@ -0,0 +1,182 @@
+import type { QualityProfile, RailsConfig } from './types.js';
+
+const PROFILE_TO_MAX_WARNINGS: Record<QualityProfile, number> = {
+  strict: 0,
+  standard: 10,
+  minimal: 50,
+};
+
+const PROFILE_TO_LINE_LENGTH: Record<QualityProfile, number> = {
+  strict: 100,
+  standard: 110,
+  minimal: 120,
+};
+
+export function eslintTemplate(profile: QualityProfile): string {
+  return `${JSON.stringify(
+    {
+      root: true,
+      parser: '@typescript-eslint/parser',
+      plugins: ['@typescript-eslint'],
+      extends: ['eslint:recommended', 'plugin:@typescript-eslint/recommended'],
+      env: {
+        node: true,
+        es2022: true,
+      },
+      parserOptions: {
+        ecmaVersion: 'latest',
+        sourceType: 'module',
+      },
+      rules: {
+        'no-console': profile === 'strict' ? 'error' : 'warn',
+        '@typescript-eslint/no-explicit-any':
+          profile === 'minimal' ? 'off' : profile === 'strict' ? 'error' : 'warn',
+        '@typescript-eslint/explicit-function-return-type':
+          profile === 'strict' ? 'warn' : 'off',
+        'max-lines-per-function': [
+          profile === 'minimal' ? 'off' : 'warn',
+          {
+            max: profile === 'strict' ? 60 : 100,
+            skipBlankLines: true,
+            skipComments: true,
+          },
+        ],
+      },
+    },
+    null,
+    2,
+  )}\n`;
+}
+
+export function biomeTemplate(profile: QualityProfile): string {
+  return `${JSON.stringify(
+    {
+      '$schema': 'https://biomejs.dev/schemas/1.8.3/schema.json',
+      formatter: {
+        enabled: true,
+        indentStyle: 'space',
+        indentWidth: 2,
+        lineWidth: PROFILE_TO_LINE_LENGTH[profile],
+      },
+      linter: {
+        enabled: true,
+        rules: {
+          recommended: true,
+          suspicious: {
+            noConsole: profile === 'strict' ? 'error' : 'warn',
+          },
+          complexity: {
+            noExcessiveCognitiveComplexity:
+              profile === 'strict' ? 'warn' : profile === 'standard' ? 'info' : 'off',
+          },
+        },
+      },
+      javascript: {
+        formatter: {
+          quoteStyle: 'single',
+          trailingCommas: 'all',
+        },
+      },
+    },
+    null,
+    2,
+  )}\n`;
+}
+
+export function pyprojectSection(profile: QualityProfile): string {
+  const lineLength = PROFILE_TO_LINE_LENGTH[profile];
+  return [
+    '# >>> mosaic-quality-rails >>>',
+    '[tool.ruff]',
+    `line-length = ${lineLength}`,
+    'target-version = "py311"',
+    '',
+    '[tool.ruff.lint]',
+    'select = ["E", "F", "I", "UP", "B"]',
+    `ignore = ${profile === 'minimal' ? '[]' : '["E501"]'}`,
+    '',
+    '[tool.black]',
+    `line-length = ${lineLength}`,
+    '',
+    '# <<< mosaic-quality-rails <<<',
+    '',
+  ].join('\n');
+}
+
+export function rustfmtTemplate(profile: QualityProfile): string {
+  const maxWidth = PROFILE_TO_LINE_LENGTH[profile];
+  const useSmallHeuristics = profile === 'strict' ? 'Max' : 'Default';
+
+  return [
+    `max_width = ${maxWidth}`,
+    `use_small_heuristics = "${useSmallHeuristics}"`,
+    `imports_granularity = "${profile === 'minimal' ? 'Crate' : 'Module'}"`,
+    `group_imports = "${profile === 'strict' ? 'StdExternalCrate' : 'Preserve'}"`,
+    '',
+  ].join('\n');
+}
+
+function resolveHookCommands(config: RailsConfig): string[] {
+  const commands: string[] = [];
+
+  if (config.kind === 'node') {
+    if (config.linters.some((linter) => linter.toLowerCase() === 'eslint')) {
+      commands.push('pnpm lint');
+    }
+    if (config.linters.some((linter) => linter.toLowerCase() === 'biome')) {
+      commands.push('pnpm biome check .');
+    }
+    if (config.formatters.some((formatter) => formatter.toLowerCase() === 'prettier')) {
+      commands.push('pnpm prettier --check .');
+    }
+    commands.push('pnpm test --if-present');
+  }
+
+  if (config.kind === 'python') {
+    commands.push('ruff check .');
+    commands.push('black --check .');
+  }
+
+  if (config.kind === 'rust') {
+    commands.push('cargo fmt --check');
+    commands.push('cargo clippy --all-targets --all-features -- -D warnings');
+  }
+
+  if (commands.length === 0) {
+    commands.push('echo "No quality commands configured for this project kind"');
+  }
+
+  return commands;
+}
+
+export function preCommitHookTemplate(config: RailsConfig): string {
+  const commands = resolveHookCommands(config)
+    .map((command) => `${command} || exit 1`)
+    .join('\n');
+
+  return [
+    '#!/usr/bin/env sh',
+    'set -eu',
+    '',
+    'echo "[quality-rails] Running pre-commit checks..."',
+    commands,
+    'echo "[quality-rails] Checks passed."',
+    '',
+  ].join('\n');
+}
+
+export function prChecklistTemplate(profile: QualityProfile): string {
+  return [
+    '# Code Review Checklist',
+    '',
+    `Profile: **${profile}**`,
+    '',
+    '- [ ] Requirements mapped to tests',
+    '- [ ] Error handling covers unhappy paths',
+    '- [ ] Lint and typecheck are clean',
+    '- [ ] Test suite passes',
+    '- [ ] Security-sensitive paths reviewed',
+    `- [ ] Warnings count <= ${PROFILE_TO_MAX_WARNINGS[profile]}`,
+    '',
+  ].join('\n');
+}
--- a/packages/quality-rails/src/types.ts
+++ b/packages/quality-rails/src/types.ts
@@ -0,0 +1,18 @@
+export type ProjectKind = 'node' | 'python' | 'rust' | 'unknown';
+
+export type QualityProfile = 'strict' | 'standard' | 'minimal';
+
+export interface RailsConfig {
+  projectPath: string;
+  kind: ProjectKind;
+  profile: QualityProfile;
+  linters: string[];
+  formatters: string[];
+  hooks: boolean;
+}
+
+export interface ScaffoldResult {
+  filesWritten: string[];
+  commandsToRun: string[];
+  warnings: string[];
+}
--- a/packages/quality-rails/templates/.gitkeep
+++ b/packages/quality-rails/templates/.gitkeep
--- a/packages/quality-rails/tests/detect.test.ts
+++ b/packages/quality-rails/tests/detect.test.ts
@@ -0,0 +1,40 @@
+import { mkdtemp, rm, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import { describe, expect, it } from 'vitest';
+
+import { detectProjectKind } from '../src/detect.js';
+
+async function withTempDir(run: (directory: string) => Promise<void>): Promise<void> {
+  const directory = await mkdtemp(join(tmpdir(), 'quality-rails-detect-'));
+  try {
+    await run(directory);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+}
+
+describe('detectProjectKind', () => {
+  it('returns node when package.json exists', async () => {
+    await withTempDir(async (directory) => {
+      await writeFile(join(directory, 'package.json'), '{"name":"fixture"}\n', 'utf8');
+
+      await expect(detectProjectKind(directory)).resolves.toBe('node');
+    });
+  });
+
+  it('returns python when pyproject.toml exists and package.json does not', async () => {
+    await withTempDir(async (directory) => {
+      await writeFile(join(directory, 'pyproject.toml'), '[project]\nname = "fixture"\n', 'utf8');
+
+      await expect(detectProjectKind(directory)).resolves.toBe('python');
+    });
+  });
+
+  it('returns unknown when no known project files exist', async () => {
+    await withTempDir(async (directory) => {
+      await expect(detectProjectKind(directory)).resolves.toBe('unknown');
+    });
+  });
+});
--- a/packages/quality-rails/tests/scaffolder.test.ts
+++ b/packages/quality-rails/tests/scaffolder.test.ts
@@ -0,0 +1,57 @@
+import { mkdtemp, readFile, rm, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import { describe, expect, it } from 'vitest';
+
+import { scaffoldQualityRails } from '../src/scaffolder.js';
+import type { RailsConfig } from '../src/types.js';
+
+async function withTempDir(run: (directory: string) => Promise<void>): Promise<void> {
+  const directory = await mkdtemp(join(tmpdir(), 'quality-rails-scaffold-'));
+  try {
+    await run(directory);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+}
+
+describe('scaffoldQualityRails', () => {
+  it('writes expected node quality rails files', async () => {
+    await withTempDir(async (directory) => {
+      await writeFile(join(directory, 'package.json'), '{"name":"fixture"}\n', 'utf8');
+
+      const previous = process.env.MOSAIC_QUALITY_RAILS_SKIP_INSTALL;
+      process.env.MOSAIC_QUALITY_RAILS_SKIP_INSTALL = '1';
+
+      const config: RailsConfig = {
+        projectPath: directory,
+        kind: 'node',
+        profile: 'strict',
+        linters: ['eslint', 'biome'],
+        formatters: ['prettier'],
+        hooks: true,
+      };
+
+      const result = await scaffoldQualityRails(config);
+
+      process.env.MOSAIC_QUALITY_RAILS_SKIP_INSTALL = previous;
+
+      await expect(readFile(join(directory, '.eslintrc'), 'utf8')).resolves.toContain('parser');
+      await expect(readFile(join(directory, 'biome.json'), 'utf8')).resolves.toContain('"formatter"');
+      await expect(readFile(join(directory, '.githooks', 'pre-commit'), 'utf8')).resolves.toContain('pnpm lint');
+      await expect(readFile(join(directory, 'PR-CHECKLIST.md'), 'utf8')).resolves.toContain('Code Review Checklist');
+
+      expect(result.filesWritten).toEqual(
+        expect.arrayContaining([
+          '.eslintrc',
+          'biome.json',
+          '.githooks/pre-commit',
+          'PR-CHECKLIST.md',
+        ]),
+      );
+      expect(result.commandsToRun).toContain('git config core.hooksPath .githooks');
+      expect(result.warnings).toHaveLength(0);
+    });
+  });
+});
--- a/packages/quality-rails/tsconfig.json
+++ b/packages/quality-rails/tsconfig.json
@@ -0,0 +1,5 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": { "outDir": "dist", "rootDir": "src" },
+  "include": ["src"]
+}
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -148,6 +148,40 @@ importers:
        specifier: ^2
        version: 2.1.9(@types/node@22.19.15)

+  packages/quality-rails:
+    dependencies:
+      '@mosaic/types':
+        specifier: workspace:*
+        version: link:../types
+      commander:
+        specifier: ^13
+        version: 13.1.0
+      js-yaml:
+        specifier: ^4
+        version: 4.1.1
+    devDependencies:
+      '@types/js-yaml':
+        specifier: ^4
+        version: 4.0.9
+      '@types/node':
+        specifier: ^22
+        version: 22.19.15
+      '@typescript-eslint/eslint-plugin':
+        specifier: ^8
+        version: 8.56.1(@typescript-eslint/parser@8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
+      '@typescript-eslint/parser':
+        specifier: ^8
+        version: 8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
+      eslint:
+        specifier: ^9
+        version: 9.39.4(jiti@2.6.1)
+      typescript:
+        specifier: ^5
+        version: 5.9.3
+      vitest:
+        specifier: ^2
+        version: 2.1.9(@types/node@22.19.15)
+
  packages/queue:
    dependencies:
      '@modelcontextprotocol/sdk':
@@ -946,6 +980,14 @@ packages:
  '@types/node@22.19.15':
    resolution: {integrity: sha512-F0R/h2+dsy5wJAUe3tAU6oqa2qbWY5TpNfL/RGmo1y38hiyO1w3x2jPtt76wmuaJI4DQnOBu21cNXQ2STIUUWg==}

+  '@typescript-eslint/eslint-plugin@8.56.1':
+    resolution: {integrity: sha512-Jz9ZztpB37dNC+HU2HI28Bs9QXpzCz+y/twHOwhyrIRdbuVDxSytJNDl6z/aAKlaRIwC7y8wJdkBv7FxYGgi0A==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      '@typescript-eslint/parser': ^8.56.1
+      eslint: ^8.57.0 || ^9.0.0 || ^10.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
  '@typescript-eslint/parser@8.56.1':
    resolution: {integrity: sha512-klQbnPAAiGYFyI02+znpBRLyjL4/BrBd0nyWkdC0s/6xFLkXYQ8OoRrSkqacS1ddVxf/LDyODIKbQ5TgKAf/Fg==}
    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
@@ -969,6 +1011,13 @@ packages:
    peerDependencies:
      typescript: '>=4.8.4 <6.0.0'

+  '@typescript-eslint/type-utils@8.56.1':
+    resolution: {integrity: sha512-yB/7dxi7MgTtGhZdaHCemf7PuwrHMenHjmzgUW1aJpO+bBU43OycnM3Wn+DdvDO/8zzA9HlhaJ0AUGuvri4oGg==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      eslint: ^8.57.0 || ^9.0.0 || ^10.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
  '@typescript-eslint/types@8.56.1':
    resolution: {integrity: sha512-dbMkdIUkIkchgGDIv7KLUpa0Mda4IYjo4IAMJUZ+3xNoUXxMsk9YtKpTHSChRS85o+H9ftm51gsK1dZReY9CVw==}
    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
@@ -979,6 +1028,13 @@ packages:
    peerDependencies:
      typescript: '>=4.8.4 <6.0.0'

+  '@typescript-eslint/utils@8.56.1':
+    resolution: {integrity: sha512-HPAVNIME3tABJ61siYlHzSWCGtOoeP2RTIaHXFMPqjrQKCGB9OgUVdiNgH7TJS2JNIQ5qQ4RsAUDuGaGme/KOA==}
+    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
+    peerDependencies:
+      eslint: ^8.57.0 || ^9.0.0 || ^10.0.0
+      typescript: '>=4.8.4 <6.0.0'
+
  '@typescript-eslint/visitor-keys@8.56.1':
    resolution: {integrity: sha512-KiROIzYdEV85YygXw6BI/Dx4fnBlFQu6Mq4QE4MOH9fFnhohw6wX/OAvDY2/C+ut0I3RSPKenvZJIVYqJNkhEw==}
    engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
@@ -1547,6 +1603,10 @@ packages:
    resolution: {integrity: sha512-hsBTNUqQTDwkWtcdYI2i06Y/nUBEsNEDJKjWdigLvegy8kDuJAS8uRlpkkcQpyEXL0Z/pjDy5HBmMjRCJ2gq+g==}
    engines: {node: '>= 4'}

+  ignore@7.0.5:
+    resolution: {integrity: sha512-Hs59xBNfUIunMFgWAbGX5cq6893IbWg4KnrjbYwX3tx0ztorVgTDA6B2sxf8ejHJ4wz8BqGUMYlnzNBer5NvGg==}
+    engines: {node: '>= 4'}
+
  import-fresh@3.3.1:
    resolution: {integrity: sha512-TR3KfrTZTYLPB6jUjfx6MF9WcWrHL9su5TObK4ZkYgBdWKPOFoSoQIdEuTuR82pmtxH2spWG9h6etwfr1pLBqQ==}
    engines: {node: '>=6'}
@@ -3004,6 +3064,22 @@ snapshots:
    dependencies:
      undici-types: 6.21.0

+  '@typescript-eslint/eslint-plugin@8.56.1(@typescript-eslint/parser@8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3))(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)':
+    dependencies:
+      '@eslint-community/regexpp': 4.12.2
+      '@typescript-eslint/parser': 8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
+      '@typescript-eslint/scope-manager': 8.56.1
+      '@typescript-eslint/type-utils': 8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
+      '@typescript-eslint/utils': 8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
+      '@typescript-eslint/visitor-keys': 8.56.1
+      eslint: 9.39.4(jiti@2.6.1)
+      ignore: 7.0.5
+      natural-compare: 1.4.0
+      ts-api-utils: 2.4.0(typescript@5.9.3)
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
  '@typescript-eslint/parser@8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)':
    dependencies:
      '@typescript-eslint/scope-manager': 8.56.1
@@ -3034,6 +3110,18 @@ snapshots:
    dependencies:
      typescript: 5.9.3

+  '@typescript-eslint/type-utils@8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)':
+    dependencies:
+      '@typescript-eslint/types': 8.56.1
+      '@typescript-eslint/typescript-estree': 8.56.1(typescript@5.9.3)
+      '@typescript-eslint/utils': 8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)
+      debug: 4.4.3
+      eslint: 9.39.4(jiti@2.6.1)
+      ts-api-utils: 2.4.0(typescript@5.9.3)
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
  '@typescript-eslint/types@8.56.1': {}

  '@typescript-eslint/typescript-estree@8.56.1(typescript@5.9.3)':
@@ -3051,6 +3139,17 @@ snapshots:
    transitivePeerDependencies:
      - supports-color

+  '@typescript-eslint/utils@8.56.1(eslint@9.39.4(jiti@2.6.1))(typescript@5.9.3)':
+    dependencies:
+      '@eslint-community/eslint-utils': 4.9.1(eslint@9.39.4(jiti@2.6.1))
+      '@typescript-eslint/scope-manager': 8.56.1
+      '@typescript-eslint/types': 8.56.1
+      '@typescript-eslint/typescript-estree': 8.56.1(typescript@5.9.3)
+      eslint: 9.39.4(jiti@2.6.1)
+      typescript: 5.9.3
+    transitivePeerDependencies:
+      - supports-color
+
  '@typescript-eslint/visitor-keys@8.56.1':
    dependencies:
      '@typescript-eslint/types': 8.56.1
@@ -3689,6 +3788,8 @@ snapshots:

  ignore@5.3.2: {}

+  ignore@7.0.5: {}
+
  import-fresh@3.3.1:
    dependencies:
      parent-module: 1.0.1