Type Parameter Naming

Enforce a single, strict naming convention for TypeScript generic type parameters using ESLint, and migrate the rule to error after a short “warn” rollout.

Rules:

• Use PascalCase for type parameters.
• Forbid leading/trailing underscores on type parameters.
• Use a small allowlist-style regex (e.g., allow either T or a PascalCase identifier such as TUser, TItem2).
• Start as warn, then switch to error once the codebase is compliant.

Example ESLint config:

// .eslintrc.cjs
module.exports = {
  rules: {
    '@typescript-eslint/naming-convention': [
      'error', // start as 'warn' for gradual rollout
      {
        selector: 'typeParameter',
        format: ['PascalCase'],
        leadingUnderscore: 'forbid',
        trailingUnderscore: 'forbid',
        custom: {
          regex: '^(T|T[A-Z][A-Za-z]+[0-9]*|[A-Z][a-zA-Z]+[0-9]*)$',
          match: true,
        },
      },
    ],
  },
}

Apply this to every generic type parameter (<TUser>, <TData2> etc.) so the meaning of identifiers stays consistent and automatically enforced across the codebase.