viewer-state-cleanup.md

Viewer State Cleanup

Overview

Fixes a memory leak where viewer state HashMap entries (tree_viewer_states, csv_viewer_states, sync_scroll_states) were not cleaned up when tabs were closed.

Key Files

• src/app.rs - Contains viewer state HashMaps and cleanup logic

Implementation Details

Problem

When tabs with structured files (JSON/YAML/TOML) or tabular files (CSV/TSV) were opened, state was stored in HashMaps keyed by tab_id. When tabs were closed, these entries remained in memory indefinitely, causing unbounded growth over open/close cycles.

Solution

Added cleanup_tab_state() helper method that removes entries from all three viewer state HashMaps:

fn cleanup_tab_state(&mut self, tab_id: usize) {
    self.tree_viewer_states.remove(&tab_id);
    self.csv_viewer_states.remove(&tab_id);
    self.sync_scroll_states.remove(&tab_id);
}

Tab Close Paths Updated

Location	Context
CLI file open	Closing empty default tab when opening files from command line
Tab bar X button	User clicks close button on tab
File deletion	Tabs auto-close when their file is deleted
Ctrl+W	handle_close_current_tab() keyboard shortcut
Confirmation dialog (Save)	User confirms save-then-close for modified file
Confirmation dialog (Discard)	User confirms close without saving

Key Pattern

Before each close_tab() call, capture the tab_id:

// Get tab_id before closing for viewer state cleanup
let tab_id = self.state.tabs().get(index).map(|t| t.id);
self.state.close_tab(index);
if let Some(id) = tab_id {
    self.cleanup_tab_state(id);
}

For confirmation dialogs, the tab_id is extracted before the dialog buttons are processed, since handle_confirmed_action() consumes the pending action.

Dependencies Used

None - uses standard library HashMap::remove().

Testing

1. Open 10+ JSON/CSV files
2. Close all tabs
3. Repeat cycle 5+ times
4. Memory should stay stable (not grow unbounded)

Note: This does not reduce baseline memory (~250MB) which is dominated by embedded fonts.