Feature Request: Multi-file context selection UI similar to Cursor's 'Add to chat'

Problem Statement

Currently, adding multiple files as context in Claude Code requires manually typing file paths with @ syntax (e.g., @file1.js @file2.py @data.csv). This becomes tedious when working with multiple files across different directories, especially compared to tools like Cursor that offer an intuitive "Add to chat" button for selecting multiple files and various file types (code, CSV, HTML, etc.).

Requested Feature

A multi-file context selection interface that allows users to:

1. Visual file selection: Browse and select multiple files from the project tree
2. Multi-format support: Include various file types (code, data files, documentation)
3. Batch context addition: Add selected files to the current conversation context
4. Clear context management: See what files are currently in context and remove them if needed

Current Workarounds & Limitations

Current methods:

• @file.js syntax for individual files
• @directory/ for directory listings
• IDE selection context (limited to current selection)

Limitations:

• Typing file paths is error-prone and time-consuming
• No visual indication of current context
• Difficult to work with files in deeply nested directories
• No batch selection capability

Suggested Implementation

Similar to Cursor's UX, this could be implemented as:

• A file picker interface accessible via keyboard shortcut or command
• Multi-select capability with checkboxes
• Context panel showing currently selected files
• Support for different file types beyond just code files

Use Cases

• Code review: Quickly add related files for comprehensive analysis
• Data analysis: Include CSV/JSON data files alongside code
• Documentation: Add multiple documentation files for context-aware updates
• Debugging: Select all relevant files for troubleshooting across modules

Related Issues

This builds on the existing request in #3967 about adding multiple files as context, but proposes a specific UX solution inspired by successful implementations in other tools.

Impact

This would significantly improve the developer experience by reducing friction in context management, making Claude Code more competitive with tools like Cursor for multi-file workflows.