Offline Mode

The Reader supports offline reading for cached content. The Reader automatically detects network connectivity and adjusts the interface. Features requiring server communication are disabled when offline. Core reading functionality remains available for cached content. A Network Status Indicator appears in the Footer when offline.

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Offline Detection

The Reader monitors network connectivity through the isOffline state variable. When offline:

A Network Status Indicator appears in the Footer displaying a message indicating the network is unavailable.

Features requiring internet are automatically disabled (grayed out or hidden).

The Reader continues to function with available offline capabilities.

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Feature Availability by Network Status

Core Reading Features

Feature	Online	Offline	Notes
Document Viewing	✅	✅	Content must be cached
Page Navigation	✅	✅
Page Layout Changes	✅	✅
Theme Selection	✅	✅
Zoom Controls	✅	✅
Table of Contents	✅	✅
Thumbnails (PDF)	✅	✅
Reading Progress	✅	✅

Features Requiring Internet

Feature	Online	Offline	Reason
Search	✅	❌	Requires server-side text search
Notebook	✅	❌	Syncs annotations with server
Highlights (new)	✅	❌	Requires sync to save
Notes (new)	✅	❌	Requires sync to save
Vito AI	✅	❌	AI processing on server
Listen (TTS)	✅	❌	Uses cloud TTS services
Dictionary	✅	❌	Fetches definitions from server
Translation	✅	❌	Uses translation API
Smart Zoom	✅	❌	Requires article data from server
Social Sharing	✅	❌	Requires internet to share

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Disabled Feature Behavior

When a feature is unavailable due to offline status:

Visual State: The button appears grayed out or with reduced opacity

Interaction: Clicking/tapping the button has no effect

Tooltip: May display a message indicating internet is required

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Network Status Indicator

When offline, a notification bar appears in the Footer:

Location: Top of the Footer component

Appearance: Styled to match the current theme

Animation: Fades in when offline, fades out when connection is restored

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Content Caching

For offline reading to work, content must be available locally:

PDF Documents

PDF pages are loaded as images from publication.files_urls.

Once loaded, pages may be cached by the browser.

Thumbnails use the same image sources and cache similarly.

EPUB Documents

EPUB content is loaded through the EPUB spine.

Chapters that have been viewed may be cached.

Navigation within cached chapters works offline.

Audiobooks

Audio files must be downloaded/cached for offline playback.

The Playlist panel works offline.

Playback controls function offline with cached audio.

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Feature Availability by Content Type (Offline)

Feature	PDF	EPUB	Audiobook
Content Viewing	✅	✅	✅*
Navigation	✅	✅	✅
Table of Contents	✅	✅	N/A
Thumbnails	✅	N/A	N/A
Playlist	N/A	N/A	✅
Theme	✅	✅	✅
Zoom/Font	✅	✅	N/A
Page Layout	✅	✅	N/A
Search	❌	❌	N/A
Notebook	❌	❌	N/A
Vito AI	❌	❌	N/A
Listen (TTS)	❌	❌	N/A

info

Audiobook playback requires cached/downloaded audio files