Tell Claude to Apply the Same Change Across Multiple Files in One Go

Some changes need to happen everywhere at once — and doing them file by file is soul-crushing. Tell Claude what to change and where, and it applies the same modification across every matching file systematically.

> add the HasUuids trait to every model in app/Models/ that
> doesn't already use it

Claude reads every model file, checks which ones already have the trait, and adds it to the rest — including the import statement, placed in the right position following your existing conventions.

This works for any repetitive cross-file change:

> wrap every controller method that returns JSON in a try/catch
> that returns a consistent error response format

> add the Searchable trait to all models that have a 'name'
> or 'title' column

> update every test file to use the new assertDatabaseHas
> syntax instead of the deprecated assertDatabaseHas with
> the table name as the first argument

> add rate limiting middleware to every API route that
> currently has no throttle middleware

Claude doesn't just find-and-replace — it understands the context of each file. When adding a trait, it checks the existing traits, places the import with the other imports, and adds it in the use statement inside the class. When wrapping methods in try/catch, it preserves the existing return types and adjusts the error response to match.

You can also target files by pattern:

> in every file that extends FormRequest, add a failedValidation
> method that returns JSON errors instead of a redirect

> find all event listener classes and add a shouldQueue property
> set to true if they don't already have one

After applying changes, tell Claude to run the tests to verify nothing broke:

> now run the tests to make sure all those changes work

One description, one prompt, every file updated. Claude turns a tedious afternoon of copy-paste into a single conversation turn.

via Claude Code