fix-once-auto-inject

Fix-Once + Auto-Inject-Future

The Problem

One-time fixes get repeated manually:

• "Add the missing import to every new file"
• "Remember to set the flag when creating services"
• Relies on human memory → fails over time

The Solution

Pair an idempotent one-time fix with a build-time auto-inject fallback.

Prong 1: One-Time Fix Script

// scripts/fix-missing-headers.cjs
const fs = require('fs');
const glob = require('glob');

const header = '// Copyright 2026 Company\n\n';

glob.sync('src/**/*.ts').forEach(file => {
  const content = fs.readFileSync(file, 'utf8');
  if (!content.startsWith('// Copyright')) {
    fs.writeFileSync(file, header + content);
    console.log(`Fixed: ${file}`);
  }
});

Run once to fix existing files.

Prong 2: Auto-Inject at Build

// In build pipeline or git hook
const files = getChangedFiles();
files.filter(f => f.endsWith('.ts')).forEach(file => {
  const content = fs.readFileSync(file, 'utf8');
  if (!content.startsWith('// Copyright')) {
    // Auto-fix or fail the build
    console.error(`Missing header: ${file}`);
    process.exit(1);
  }
});

Git Hook Version

#!/bin/bash
# .git/hooks/pre-commit

for file in $(git diff --cached --name-only | grep '\.ts$'); do
  if ! head -1 "$file" | grep -q "Copyright"; then
    echo "Missing copyright header: $file"
    exit 1
  fi
done

Pattern

┌─────────────────────────────────────┐
│  Fix existing files (one-time)      │
│  node scripts/fix-all.cjs           │
└─────────────────────────────────────┘
                 │
                 ▼
┌─────────────────────────────────────┐
│  Enforce on new files (ongoing)     │
│  build hook / pre-commit / CI       │
└─────────────────────────────────────┘

Verification

1. Running fix script on already-fixed files is idempotent
2. Creating a new file without the fix fails the hook
3. No manual enforcement needed after setup

When to Apply

• License headers
• Required imports
• Configuration defaults
• Any "every file must have X" rule