Ask Claude to Split a Large File into Smaller, Focused Modules

Files grow. A util that started at 50 lines hits 500, a controller handles six different resources, or a component file contains three components that should be separate. Claude Code can split them cleanly.

src/utils/helpers.ts is 800 lines with unrelated functions. 
Split it into focused modules — one for string helpers, one for date helpers, 
one for validation helpers. Update all imports across the codebase.

Claude reads the file, groups related functions, creates the new modules, and updates every import across your project. The tricky part — making sure nothing breaks — is exactly what Claude handles well because it searches for all references before changing anything.

This works for all kinds of large files:

# Split a god object
UserService.ts has user CRUD, auth, notifications, and billing. 
Split it into UserService, AuthService, NotificationService, 
and BillingService. Keep the same public API where possible.

# Extract components
This React file has three components in one file. 
Extract each into its own file in the same directory.

# Split a route file
routes.ts has 50 routes. Split it into auth routes, api routes, 
and admin routes, then import them from the main router.

# Extract a class
This file has a class and several helper functions that only that class uses. 
Move the class and its helpers into their own module.

For maximum safety, ask Claude to verify after splitting:

After splitting the file, run the tests and check that all imports resolve. 
If anything breaks, fix it before moving on to the next split.

The key insight: Claude doesn't just move code — it understands the dependency graph. It knows which functions call which, what's exported vs internal, and where the clean boundaries are.

Large files aren't a code smell you can lint — they're a structure problem. Let Claude find the seams and split along them.

via Claude Code