Working Across the Entire Project

Working Code

Let's request changes across multiple files:

> Find all console.log statements in the project and replace them with a proper logging library (winston).
> Also create a logger configuration file.

Claude modifies several files at once, showing you the diff for each file and asking for approval.

More complex refactoring is also possible:

> Apply error handling middleware to all route handlers in src/api/.
> Find handlers that don't have try-catch and wrap them with asyncHandler.

Try It Yourself

Use the @ symbol to include specific files in the context:

> Based on the User type in @src/types/user.ts,
> add types to all functions in @src/api/users.ts

This makes Claude prioritize those files as references.

Before large-scale changes, always set up safety measures:

> Save the current state with git stash before starting changes

Or create a branch:

> Create a branch called refactor/logging and work there

"Why?" — Project-Scale Work Is Where Claude Code Shines

Single-file editing can be done with any tool. What makes Claude Code special is its ability to understand the full project context and change multiple files consistently.

Multi-File Work Checklist

1. Before changes: Create a Git branch or save with stash
2. When requesting: Clearly communicate the scope and rules
3. During review: Carefully check each file's diff
4. After changes: Run tests to catch regressions

File Targeting with @ Mentions

| Usage | Meaning | | ---------------- | ---------------------------------- | | @src/config.ts | Include a specific file in context | | @src/utils/ | Reference an entire directory | | @package.json | Reference a config file |

Large-Scale Refactoring Prompt Example

> Unify all API response formats in this project.
> Current: each endpoint uses its own format
> Goal: standardize to { success: boolean, data: T, error?: string }
> Define the common type in @src/types/response.ts,
> and update all handlers in @src/api/.

Deep Dive