# Command History Navigation Implementation
## Changes Made
1. **Modified key bindings** in `src/tui/mod.rs`:
- **Before**: Ctrl+Up/Down arrows for history navigation
- **After**: Regular Up/Down arrows navigate history when input is empty
2. **Key behavior**:
- When input is empty: Up/Down arrows navigate command history
- When input has content: Up/Down arrows scroll the message list
- Ctrl+R still searches history with prefix matching
3. **Implementation details**:
- Uses existing `command_history: Vec<String>` storage
- Uses existing `history_index: Option<usize>` for position tracking
- Uses existing `navigate_history()` method for logic
- Preserves history across session (until TUI exits)
## Acceptance Criteria Verification
✅ **Submitted messages stored in Vec<String> history**: Already implemented in `submit_message()`
✅ **↑/↓ arrows navigate history when input is empty**: New behavior implemented
✅ **History persists for current session**: Uses existing `command_history` which persists for the TUI session
✅ **New input clears history position**: `submit_message()` sets `history_index = None`
## Testing Checklist
- [ ] Start TUI and submit a few messages
- [ ] Press Up arrow when input is empty - should show previous message
- [ ] Press Down arrow - should navigate forward in history
- [ ] Type something in input - Up/Down should scroll instead
- [ ] Submit a new message - should clear history position
- [ ] Ctrl+R should still work for search