# Timeline & Photos

This document describes the photo timeline, asset display, and related functionality.

## Timeline Overview

The timeline is the main view of the app, displaying all photos and videos in chronological order (newest first).

## Asset Types

### Asset States
```
┌─────────────────────────────────────────────────────────────┐
│                        Asset States                          │
├───────────────┬───────────────┬─────────────────────────────┤
│    LOCAL      │    REMOTE     │         MERGED              │
├───────────────┼───────────────┼─────────────────────────────┤
│ On device     │ On server     │ Both device and server      │
│ Not uploaded  │ Not on device │ Linked by checksum          │
│ localId set   │ remoteId set  │ Both IDs set                │
└───────────────┴───────────────┴─────────────────────────────┘
```

### Asset Model
```
Asset {
  id: String              // Unique identifier
  name: String            // Filename
  type: AssetType         // image, video, audio, other
  createdAt: DateTime     // When created/taken
  updatedAt: DateTime     // Last modified
  checksum: String?       // File hash for deduplication
  width: Integer?         // Image/video width
  height: Integer?        // Image/video height
  durationInSeconds: Int? // Video duration
  isFavorite: Boolean     // Marked as favorite
  isArchived: Boolean     // Hidden from timeline
  isTrashed: Boolean      // In trash
  livePhotoVideoId: String? // Paired video for live photos

  // State indicators
  localId: String?        // Device gallery ID
  remoteId: String?       // Server asset ID
  storage: AssetState     // local, remote, or merged
}
```

### Asset Types Enum
| Type | Description |
|------|-------------|
| image | Photos (JPEG, PNG, HEIC, etc.) |
| video | Videos (MP4, MOV, etc.) |
| audio | Audio files |
| other | Other file types |

### Playback Styles
| Style | Description |
|-------|-------------|
| image | Static image |
| video | Full video |
| imageAnimated | GIF or animated image |
| livePhoto | Photo with motion component |
| videoLooping | Short looping video |

## Timeline Display

### Grid Configuration
- **Tiles per row**: Configurable (default: 4)
- **Dynamic layout**: Optional variable row heights
- **Group by**: Day, Month, or None

### Date Headers
Assets are grouped by date with section headers:
```
December 2024
├── Dec 15 (if grouping by day)
│   └── [asset grid]
├── Dec 14
│   └── [asset grid]
...
```

### Asset Thumbnail Display
Each asset shows:
- Thumbnail image
- Video duration (if video)
- Live photo indicator (if motion photo)
- Favorite indicator (heart icon)
- Selection checkbox (in multi-select mode)
- Stack indicator (if part of stack)

## Loading Strategy

### Pagination
- Timeline loads in batches (default: 1024 assets)
- Additional assets loaded when scrolling
- Opposite direction pre-loading (64 assets)

### Thumbnail Loading
1. Check local cache first
2. Load from local device if available
3. Fetch from server with thumbhash placeholder
4. Cache for future use

### Image Quality Levels
| Level | Use Case | Resolution |
|-------|----------|------------|
| Thumbhash | Instant placeholder | ~4x4 blurred |
| Thumbnail | Grid view | ~250px |
| Preview | Full screen initial | ~1080px |
| Original | Full zoom | Full resolution |

## Multi-User Timeline

When partner sharing is enabled:
- Timeline can include multiple users' assets
- Assets are merged chronologically
- User indicator shows asset owner

## Multi-Select Mode

### Activation
- Long press on any asset
- Or tap select button in app bar

### Available Actions
```
┌─────────────────────────────────────────────────────────────┐
│  [X] Cancel   Selected: 5                                   │
├─────────────────────────────────────────────────────────────┤
│  ♥ Favorite  │  📦 Archive  │  🗑 Delete  │  📤 Share  │ ⋮ │
└─────────────────────────────────────────────────────────────┘
```

### Actions Available
| Action | Description |
|--------|-------------|
| Favorite | Toggle favorite status |
| Archive | Move to archive |
| Delete | Move to trash |
| Share | Share via system share |
| Download | Download to device |
| Add to Album | Add to existing/new album |
| Create Stack | Stack selected assets |
| Move to Locked | Move to locked folder |

## Pull to Refresh

### Refresh Behavior
1. Single pull: Incremental sync
2. Double pull (within 4 seconds): Full refresh
   - Clears local cache
   - Re-fetches all data

### Sync Process
1. Check server for new assets
2. Download metadata for new assets
3. Update local database
4. Refresh album data
5. Update UI

## Memory Lane

### Display
- Horizontal scrolling widget at top of timeline
- Shows "X years ago" cards
- Only visible if user has memories enabled

### Memory Card
```
┌─────────────────┐
│   [Thumbnail]   │
│                 │
│   2 years ago   │
└─────────────────┘
```

### Memory API
```
GET /memories?for={today's date}

Response: Array of Memory objects
{
  "id": "memory-id",
  "data": {
    "year": 2022
  },
  "assets": [...]
}
```

## Scroll Scrubber

### Features
- Appears on right side when scrolling
- Shows date labels
- Drag to quickly navigate
- Snaps to month boundaries (if enough history)

### Configuration
- Enabled when timeline spans 12+ months
- Custom scroll controller for smooth navigation

## Asset Visibility

Assets can have different visibility states:

| State | Timeline | Archive | Trash | Locked |
|-------|----------|---------|-------|--------|
| Normal | ✓ | | | |
| Archived | | ✓ | | |
| Trashed | | | ✓ | |
| Hidden/Locked | | | | ✓ |

## Asset Stacks

Multiple similar assets can be "stacked":
- Only primary asset shown in timeline
- Stack indicator shows count
- Tap to view stack contents
- Can unstack to separate

## Real-time Updates

Via WebSocket connection:
- New uploads appear immediately
- Deletions remove assets from view
- Updates refresh asset metadata

### WebSocket Events
| Event | Action |
|-------|--------|
| on_upload_success | Add new asset to timeline |
| on_asset_delete | Remove asset |
| on_asset_trash | Move to trash |
| on_asset_restore | Restore from trash |
| on_asset_update | Refresh metadata |
| on_asset_hidden | Hide from timeline |

## Performance Optimizations

1. **Virtualized list**: Only renders visible items
2. **Image caching**: Configurable cache size
3. **Lazy loading**: Load data as needed
4. **Debounced scroll**: Reduce render calls
5. **Background prefetching**: Load ahead

### Cache Settings
| Setting | Default | Description |
|---------|---------|-------------|
| thumbnailCacheSize | 10000 | Max cached thumbnails |
| imageCacheSize | 350 | Max cached full images |
| albumThumbnailCacheSize | 200 | Max album thumbs |

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