Transferred size: 207KB. The size is the app's advantage. Initial loading has been optimised.

The contest task is almost completed, the app can send and display most media types. The overall speed is slightly above average – the right sidebar has issues when expanding. Chats are a bit slow to appear when the page is reloaded, there is room for improvement. The design of the app does not fully comply with the provided mockups. Issues identified in our feedback for Stage 1 were not fixed.

The following new issues were found during testing:

– No way to open Saved Messages, this chat is not available in the chats list / side menu.
– Missing pinned messages.
– When the right sidebar is expanded, it shows data from the previously opened chat.
– Low resolution when using the media viewer.
– Voice messages looks the same as music files.
– Some profile photos are missing.
– Media previews blink on loading in Shared Media.
– Animated stickers and GIFs blink while being sent.
– Inconsistencies with UI – stickers, videos and video messages have an author.
– A progress bar is spinning continuosly when the right sidebar is empty.
– Sending two photos causes one of them to disappear until the chat is reopened.
– Missing sticker set previews in stickers tab, only vertical scrolling is available to browse all the added sets.
– If a long-named entity is pinned, opening it causes the chat list to resize; also such entities break the layout in the right sidebar.
– No support for Apple emoji.

On the positive side, the search implementation is very nice. However a small glitch should be fixed: while the right sidebar is expanded, pressing the search icon several times multiplies the search screen.

UPD.

Transferred size on startup: 140KB
Transferred size after logging in: 207KB

Handling updates:
- Updates dialogs in the left sidebar with new messages
- Rearranges dialogs in the sidebar when new message is received
- Updates unread count when message is seen on another device
- Deletes message when delete update is received
- Marks message as read on read outbox
- Shows is typing status

Message media:
* Lightbox:
- Full implementation of media lightbox
- Playing video in lightbox
- Lightbox animation when media is opened from a chat
- Lightbox animation when navigating through media
- Lightbox animation for sender profile details
- Download media in lightbox
- Download progress indicator
* Audio
- Supports audio and voice playback
- Renders waveform for audio messages
- Download progress indicator
* Video
- Video playback in chat (muted)
- GIF playback
- Download progress indicator
* Files
- Download files with progress indicator
- Show file size
* Photo
- Displays photo in chat (m)
- Downloads higher rsolution in lightbox

Send message:
- Emoji picker
- Sticker picker and sending stickers from installed stickers
- Lazy loading sticker sets with infinite scroll
- GIF picker and sending GIFs from saved GIFs
- Lazy loading saved GIFs with infinite scroll
- Reply to a message
- Send continous "is typing" signal every 4500ms until finishing typing

Upload media and documents:
- Upload documents
- Upload media
- Upload modal for media and media preview
- Video thumbnail preview in upload modal
- Automatically resize and compress large photos before sending
- Upload modal for documents
- Upload progress indicator

Cosmetic improvements:
- Left sidebar navigation button animation (From menu to back button)
- Message bubble tail
- Showing spinners when loading chats and dialog lists
- Styles are fully compatible with RTL languages (Farsi, Arabic, Hebrew)

Left sidebar:
- Shows top peers before starting search
- Global search for messages and contacts
- Animated menu button

Right sidebar:
- Show profile details (about/bio, phone number, username, profile photo)
- Shared media (photos and videos) with infinite scroll
- Open light box from shared media with animation
- Shared links with infinite scroll
- Shared docs with infinite scroll (downloadable from the same panel)
- Shared audio with infinite scroll (downloadable and playable from the same panel)

Chat:
- Supports showing replied message
- Clicking on a replied message scrolls to the original message
- Supports showing forwarded messages
- Bi-directional loading for message history
- Loads chat from unread position
- Marks message as read when gets into view port
- Full message entity parsing support
- Partial support for translating all message service actions to text
- Context menu on bubble right click
* Copying a message
* Reply to a message

html injection in dialog list and chat header