Auto-Save Feature

January 17, 2026 · View on GitHub

Overview

Ferrite implements a configurable auto-save feature that saves documents after a configurable idle delay. The feature uses a temp-file based strategy to prevent data loss without overwriting the main file prematurely.

Key Features

  1. Per-document toggle - Each tab can have auto-save enabled/disabled independently via toolbar button
  2. Settings-based defaults - New documents inherit auto-save state from settings
  3. Idle-based triggering - Saves after configurable idle delay (not interval-based)
  4. Temp file strategy - Writes to .autosave/ in config directory, not the main file
  5. Recovery on open - Detects newer temp files and offers restore/discard
  6. Atomic writes - Uses temp file + rename for crash safety

Settings

SettingTypeDefaultDescription
auto_save_enabled_defaultboolfalseDefault auto-save state for new tabs
auto_save_delay_msu3215000Delay in ms before auto-save triggers

Settings are configurable in the Settings panel under "Files" section.

Architecture

State Management

// Tab struct fields for auto-save
pub struct Tab {
    pub auto_save_enabled: bool,              // Per-tab toggle
    pub last_edit_time: Option<Instant>,      // For idle detection
    last_auto_save_content_hash: Option<u64>, // Change detection
}

Key Methods

  • Tab::toggle_auto_save() - Toggle auto-save for this tab
  • Tab::mark_content_edited() - Called when content changes (updates last_edit_time)
  • Tab::should_auto_save(delay_ms) - Check if auto-save should trigger
  • Tab::mark_auto_saved() - Mark content as auto-saved (updates hash)

Temp File Storage

Auto-save files are stored in:

~/.config/ferrite/autosave/
├── filename_<hash>.md.autosave     # For saved files
└── untitled_<tab_id>.md.autosave   # For unsaved documents

Each auto-save file contains:

  1. JSON metadata line (tab ID, original path, timestamp, content hash)
  2. Blank line separator
  3. Document content

Auto-Save Flow

  1. Content edited → set_content() calls mark_content_edited()
  2. Main loop → process_auto_saves() checks each tab
  3. If should_auto_save → Write to temp file, mark_auto_saved()
  4. Manual save → cleanup_auto_save_for_tab() deletes temp file

Recovery Flow

  1. File opened → check_auto_save_recovery() checks for newer temp file
  2. If found → Store AutoSaveRecoveryInfo for dialog
  3. Update loop → show_auto_save_recovery_dialog() renders modal
  4. User chooses → Restore content or discard temp file

UI Components

Toolbar Button

Located in the File group of the ribbon:

  • Icon: ⏱ (enabled) / ⏸ (disabled)
  • Color: Green background when active
  • Action: RibbonAction::ToggleAutoSave

Settings Panel

Under "Files" section:

  • Checkbox: "Enable Auto-Save by Default"
  • Slider: Auto-save delay (5-300 seconds)
  • Presets: 15s, 30s, 1m buttons

Recovery Dialog

Modal dialog shown when opening file with newer auto-save:

  • Shows file path and time since auto-save
  • Buttons: "✅ Restore" and "🗑 Discard"

Cleanup

Auto-save temp files are cleaned up:

  • After manual save (via Save or Save As)
  • After user discards recovery
  • After user restores from recovery
  • src/config/settings.rs - Settings definitions
  • src/config/session.rs - Temp file functions
  • src/state.rs - Tab auto-save state
  • src/app.rs - Auto-save processing, recovery dialog
  • src/ui/ribbon.rs - Toolbar toggle button

Testing

Manual Test Cases

  1. Enable auto-save, edit, wait > delay → Verify temp file created in config dir
  2. Manual save → Verify temp file cleared
  3. Crash simulation → Kill process, restart, open file → Verify recovery prompt
  4. Per-editor toggle → Verify independent auto-save state per tab
  5. Large file → Verify no UI lag during auto-save (atomic write)

Verify Temp File Location

Windows: %APPDATA%\ferrite\autosave\ Linux: ~/.config/ferrite/autosave/ macOS: ~/Library/Application Support/ferrite/autosave/