Add Text Selection and Selective Copy Feature

[bgreenwell]

Currently, doxx copies entire views (full document, complete outline, or all search
results) when using the copy functionality (c key). Users often want to copy just
specific portions of text, making the current all-or-nothing approach less practical for
many use cases.

Proposed Solution

Implement text selection capabilities that allow users to select and copy specific portions
of document content.

Implementation Options

Option 1: Mouse Selection (Recommended)

• Interaction: Click and drag to select text
• Visual feedback: Highlight selected text with different background color
• Copy: Press c to copy selected text to clipboard
• Pros: Intuitive, familiar to most users
• Cons: Requires mouse support, coordinate mapping complexity

Option 2: Keyboard Selection (Vim-like)

• Interaction:
  • Press v to enter visual selection mode
  • Use arrow keys to expand/contract selection
  • Press c or Enter to copy selection
  • Press Esc to exit selection mode
• Visual feedback: Highlight selected text
• Pros: Keyboard-only workflow, familiar to vim users
• Cons: Learning curve for non-vim users

Option 3: Line-based Selection

• Interaction:
  • Press Shift + ↑/↓ to select entire lines/paragraphs
  • Press c to copy selected lines
• Visual feedback: Highlight selected lines
• Pros: Simpler to implement, good for structured content
• Cons: Less granular than character-level selection

Technical Considerations

Challenges

1. Coordinate mapping: Convert terminal grid coordinates back to document content
   positions
2. Content types: Handle selection across headings, paragraphs, lists, and tables
3. Text wrapping: Manage selection across wrapped lines
4. Visual rendering: Implement selection highlighting in ratatui
5. Multi-view support: Selection behavior in Document, Outline, and Search views

Implementation Details

• Extend App struct with selection state (selection_start, selection_end,
  selection_active)
• Add selection rendering in UI components
• Modify copy functionality to use selected text when available
• Handle edge cases (empty selection, invalid ranges, etc.)

User Experience

Keyboard Shortcuts (Proposed)

• v - Enter visual selection mode (Option 2)
• c - Copy selected text (or full view if no selection)
• Esc - Clear selection / exit selection mode
• Arrow keys - Expand/contract selection in visual mode
• Mouse drag - Select text (Option 1)

Visual Indicators

• Selected text highlighted with inverted colors or different background
• Status bar indicator when in selection mode
• Selection bounds clearly visible

Benefits

• Improved usability: Copy only what you need
• Better workflow: Reduce need to paste and then select in external apps
• Competitive advantage: Feature not available in basic document viewers
• Professional feel: Expected feature in modern terminal applications

Priority

Phase 3 - After AI integration is complete. This is a significant UX enhancement that
requires careful implementation but would greatly improve the user experience.

Acceptance Criteria

• Users can select text using chosen interaction method
• Selected text is visually highlighted
• Copy functionality works with selected text
• Selection works across all view modes (Document, Outline, Search)
• Selection handles different content types (headings, paragraphs, lists, tables)
• Clear visual feedback for selection state
• Intuitive keyboard shortcuts
• Proper handling of edge cases

Related Issues

• Depends on stable core functionality
• May interact with future search highlighting features
• Could integrate with planned vim-like navigation enhancements