# Session.rs Module Architecture
## Module Organization
```text
session.rs (main coordinator)
palette.rs - File & prompt palette management
editing.rs - Text editing & cursor movement
messages.rs - Transcript message operations
reflow.rs - Text wrapping & layout
state.rs - Lifecycle & state management
events.rs - Event handling (existing)
command.rs - Command execution (existing)
render.rs - UI rendering (existing)
input.rs - Input display (existing)
header.rs - Header rendering (existing)
modal.rs - Modal dialogs (existing)
scroll.rs - Scroll manager (existing)
transcript.rs - Transcript cache (existing)
input_manager.rs - Input state (existing)
styling.rs - Style helpers (existing)
... (other supporting modules)
```
## Refactored Modules (New)
### palette.rs
- Manages file and prompt palette lifecycle
- Handles palette triggers and key events
- Inserts references into input
### editing.rs
- All text insertion and deletion
- Cursor movement (char, word, line)
- History navigation (currently disabled)
### messages.rs
- Message line operations (push, append, replace)
- Tool code fence handling
- Message styling and prefixes
### reflow.rs
- Transcript line wrapping
- Tool and PTY output formatting
- Diff line padding
- Text justification for agent messages
### state.rs
- Session initialization
- Exit and redraw management
- Modal management
- Scroll operations
- Cache invalidation
## Design Principles
1. **Single Responsibility**: Each module has one clear purpose
2. **Cohesion**: Related functionality grouped together
3. **Low Coupling**: Minimal dependencies between modules
4. **Information Hiding**: Internal methods use `pub(super)`
5. **Zero-Cost**: No runtime overhead from refactoring
## Benefits
- **Reduced complexity**: Smaller, focused files
- **Better navigation**: Clear where to find functionality
- **Easier testing**: Isolated concerns
- **Maintainability**: Changes localized to relevant modules
- **Onboarding**: New developers can understand modules incrementally