Transferred size: 248KB. Оптмизирован первый запуск и скорость отображения чатов после перезагрузки страницы.

В работе учтены многие замечания по итогам первого этапа. Конкурсное задание выполнено практически полностью, лишь отдельные элементы приложения не соответствуют предложенному дизайну.

Скорость приложения оказалась средней, в ходе тестирования были выявлены следующие недостатки в производительности:
– Задержка при переходе на экран чатов после введенного пароля двухэтапной аутентификации, задержка появления списка чатов;
– Третья колонка в чатах с большим количеством сообщений открывается рывками;
– Приложение серьёзно теряет в производительности при открытии предпросмотра анимированных стикеров;
– Кроме того, заметно серьёзное снижение производительности при последовательном переходе в несколько разных бесед подряд.

Прочие недостатки:
– Приложение иногда может терять сеть – независимо от стабильности подключения появляется плашка 'Waiting for network';
– В некоторых случаях медиа могут не прогружаться;
– Отсутствует навигация по медиа;
– Бесконечная загрузка в третьей колонке при отсутствии медиа;
– Не у всех сообщений есть индикатор прочитанности;
– Набранное и неотправленное сообщение в поле ввода отображается во всех чатах;
– Сущности с длинными названиями ломают вёрстку в их шапках и профилях;
– Ползунок прокрутки прыгает в середину экрана сверху.

UPD.

Transferred size при первом старте:221KB
Transferred size после перезагрузки страницы для залогиненного аккаунта: 248KB

nda nu i hueta

+ Nice and smooth animations and transitions everywhere.
+ Fast and responsive. Web worker is must have, you are right. Though probably file download speed may be improved, but I believe it was your choice to limit it to keep other parts responsive.
+ Previews for files with media mime types.
+ Reactions for messages are visible. Cool.
+ Navigation by replies is working. Great.
+ 'Scroll to most recent' button.
+ Links section in right sidebar.
+ 'Connecting...' div when there's internet issues.
+ It really does removes messages when they are removed from other session. Awesome.

- Avatars from I believe diffferent dc are not loaded on the start. They are here after page reload.
- No navigation and extra buttons other than close 'x' in media browser (full view). 'Today' in current day date is a good catch though.
- No recent emoji. Stickers category navigation is not fully implemented (doesn't scroll on x, no previews for most packs)
- There is no way to add/remove stickers pack. Though sticker popup is fast and smooth.
- File upload is smooth, progress bar there, but there's no upload media functionality.
- Downloading the same file again doesn't work. Also, it doesn't display downloading status when there's same file in right sidebar and in chat messages list.

- Sometimes it takes too much time to initialize 'Media' section in sidebar and I see heavy CPU load and see many 'FLOOD_WAIT_' in console. May be because it loads too much messages to find some media? But it also displays loading animation forever when there's no messages for current peer at all, may be related.
- Date formats are different from design for file elements.
- Videos and round videos are not implemented.
- New message textarea should probably allow new lines on enter when in full-height mode.


-+ Looks that previews are cached and load faster after page reload, but it takes relatively much time to do this, probably there're ways to improve.
-+ I know it's design flaws, not yours, but I'd let it be responsive up to at least 1920x screen. Doesn't look very good in full screen browser with narrow white areas near left and right edges.

I really like this work.

+Good smooth animations
+Support many file types
+Download files

Couple of comments:
-No send media
-No support send gifs
-Not all stickers loaded properly
-With first login there is error (see screenshot)

No global search in left sidebar
Real nicknames and avatars do not match the color of the regular version of the client
No new emojies
Bugs with chat layout (replies and common messages, screen below)
No media players, videos doesnt work
Audio doesnt work
Cannot enter text until you click a text field with a mouse.
Scrolling and content bug if you press mouse3 and try to scroll chat history
No message popups with edit, copy, etc.
No upload media popup. Cant copy media too.
Sticker sets cannot load
The application freezes once.
When sending a message - there is not mark that it was sent
In many places layout does not match mockups
When an image is uploaded, it is not displayed. But there is a upload loader.
When sending, the image in the chat does not display correctly, does not open as media
If there is no media in the dialogue, then loader bug
If audio forward - no forward, no audio, but i can download

+Deleted messages
+Send message with enter.
+Chat virtualization
+Caching

No dates in chat :( why?