Global notes:
1. The view layer is rewritten from the ground up one more time. Now it uses React-like components with hooks.
2. All auth keys (not only main DC, as before) stored in localStorage.
3. IndexedDB is used for caching parts of streaming media. Cache Storage is used for caching images.
4. Preloading next chunk of messages. For example, when user scrolls up, requested messages are loading, then next messages (with same options, but offsetId of first loaded message)
5. All expensive computation tasks moved to WebWorker (in addition to the previous stage, AES CTR and converting stripped photos to jpg)
Summing up previous points, app performance has increased significantly.
6. Auto Reconnecting (disabled by default, you can turn it on in Other settings), for example, after locking the phone.
7. Fixed layout to fit design mockups.
8. Fixed all bugs from previous stages, except Apple-emojis on other platforms.

Implemented all of Minimum Requirements and Reward Requirements:
1. Mobile Version.
2. Emoji, stickers and GIFs
3. Recording voice messages
4. Search for chats
5. Shared Media and Gallery
6. Audio and video streaming
7. Archive
8. Folders
9. Polls of all types.
10. Search for messages inside a particular chat.

Extra features:
Internationalization

Notes:
- Waiting for stop bounce scrolling on IOS before prepending new messages for correctly scroll to previous top message. Then scroll a little bit to indicate that messages are loaded.
- Correct width of messages, depending on media (image, video, web-page)
- Correctly opening new user from search, for example, Quiz Bot, and starting some quiz ("/start ID_OF_QUIZ")
- Buttons Layout to support starting of Quiz Bot.
- All types of service messages.
- All types of typing content. (typing, sending file, recording...)
- Pinning dialogs from context menu
- Archiving dialogs from context menu
- Preloading new messages in media viewer
- Correctly loading answers after time exceed in quiz mode.
- Scroll down chat view when a new message is received and scroll position near last message. Always scroll down after send message.
- initial scroll position of first unread message
- sending read acknowledge when message appears in viewport

- audio synchroniztion between chat view, header player and shared media

Transferred size при первом старте: 698KB.
Transferred size после перезагрузки страницы для залогиненного аккаунта: 840KB.

В целом, скорость работы приложения средняя – приложение недостаточно оптимизировано для работы на менее производительных устройствах. Приложение практически полностью соответствует дизайну предоставленных макетов, но не все замечания по итогам предыдущих этапов приняты во внимание.
В ходе тестирования приложения было выявлено множество проблем, в том числе критических: как в первой части задания, так и во второй. Из-за них работа не может занять более высокое призовое место. 

1. Критические недоработки
– В Safari на iOS наблюдаются проблемы со входом, когда на первом экране происходит бесконечное обновление страницы;
– В чатах не отображаются закрепленные сообщения;
– Не поддержано корректное отображение альбомов и пересланных сообщений;
– Не отображаются некоторые стикеры и GIF;
– Голосовые сообщения, записанные с iPhone XS, не проигрываются на этом же устройстве;
– Попытка набрать текстовое сообщение и отправить его в момент записи голосового ломает кнопку отправки — отображается микрофон до момента обновления страницы;
– Двойное-тройное касание по кнопке микрофона и последующая попытка отправки ломают интерфейс – голосовое сообщение продолжает записываться, отображаясь во всех чатах. Отправить текст или другое голосовое сообщение уже невозможно до обновления страницы.

2. Прочие недоработки
– Видео возможно отправить только документом;
– В альбомном режиме в Safari на iOS не отображается поле ввода нового сообщения; 
– Контекстное меню на беседах в нижней части списка чатов открывается за пределами экрана на Android (Chrome);
– В результатах поиска сообщения из групп отображаются как сообщения из личных чатов;
– Если в поле ввода присутствуют только эмодзи, не появляется кнопка отправки;
– Не продумана работа в альбомной ориентации с панелью стикеров и GIF – невозможно перейти к самим файлам;
– Не реализован поиск по GIF.

3. Недоработки второй части задания 
– При перезагрузке страницы смаргивает окно логина;
– В работе не реализован стриминг для мобильных устройств в Safari;
– Закрепление чата в архиве закрепляет его и в основном списке – при разархивировании чат будет закреплён в общем списке бесед;
– Некоторые медиа отображаются растянутыми при работе с приложением в альбомной ориентации;
– Отсутствует вкладка Recent в поиске;
– Не реализована прокрутка свайпом в галерее;
– При получении нового сообщения в архивированном чате он не вылетает в общий список;
– Редактирование папок возможно только из списка чатов;
– Объяснения в опросах не поддерживают разметку;
– Список проголосовавших в опросах обновляется с опозданием;
– Не реализован поиск по дате внутри чата.

The corner of the message is white until loading the image.

App doesn't load after entering code confirmation.

Pressing a letter-key('a','b'...) in the field for your phone number (when logging in) will empty the field for the country.

Expanding the list of countries (when logging in) will create a scroll-bar for the whole window (which was not there before, that is great) and thus changing aspects a little bit (causing an tiny yet still unpleasant glitch).
Nitpicky issues from the "attention to detail"-category...

Firs of all I want to say thank you for adding my country in country list. but there is an Inaccuracy: the correct phone code is +7 940 (840 code is for
landline phones). Short name of country is "AB" or "ABH".
And I have a problem accessing the site from a mobile phone. The site is initially loaded, but then all the text is replaced with a solid white canvas. Using a site from phone is simply impossible. Thank you for your attention!

country is not determined automatically (login page)
layout does not match the mockups
no context menu in chat
no caching in dialogs ?
there are no animations at work, left-right sidebar, etc.
no media viewer animations
sidebar closes when switching between dialogs
messages where there are reply are long rendered in the chat
no emoji in chat/emoji panel/dialog list etc.
the list of folders cannot be scrolled with the mouse wheel
streaming audio works, but not quite correctly, every time you rewind, the progress is reset, and already downloaded is not displayed
also, when rewinding audio to different places, for some reason, the same place is always played
audio and voice messages do not switch to the next when playback is finished
when the audio ends it disappears from the topbar
the dialog with the saved messages in the list of pinned folders is not displayed

GIFs do not download automatically, photos, too, streaming GIFs do not work ?
video streaming does not work well when rewinding
if you hold down the mouse button 3 to scroll the chat, the scroll stops in one place and the history doesnt load
often the chat media just doesn’t load, it remains blurry, and the other one requires you to manually press the download button
in forwarded messages, just a nickname is displayed, which is not very clear
for some reason sometimes the media does not open when you click on the photo in the right sidebar
waveform progress slows down and goes jerky
work is not optimized, for 10 minutes tests >1.5GB. memory leak in different places, for example in the sticker panel (check the video)
with prolonged use of the application, the dialogue may open sluggishly and for more than 2 seconds the entire screen freezes during ripple animation
unread messages do not work correctly, and also not all messages are displayed

when you enter the dialog, you cannot type until you click on the input field
there is no sidebar caching, every time 2 loaders appear on it
recent search doesnt work
the search does not highlight the found word
sticker set search is not working properly (check the video)
search for stickers is buggy if you close and open the panel again, you cannot click on the input field (check the video)
some dialog avatars do not load, and also substitutes incorrect avatars if you enter the dialog. (check the video)
in chat half of the stickers just do not load
sticker animation doesn’t work const, works when hover
sticker popup doesnt open from chat
trending stickers open in the emoji panel instead of the right sidebar
from trending stickers you can’t open a popup with a set of stickers, they also don’t have animations

https://t.me/hawk1414 - videos/screens here

> If you are in Russia, do you use VPN? Maybe there is some problem with connection to DC where avatar is stored.
no, I'm from Ukraine

> I couldn't find mockup with stickers on right sidebar. Does it exist? I Made it the same as in MacOS app by default.
JS_3 > Chat_SearchStickers_1.png , sidebar with header, this is definitely not an emoji panel

>> the list of folders cannot be scrolled with the mouse wheel
> can't reproduce it
Sorry, I meant the slider in the dialog list, he doesn't scroll

> I don't understand
In chat forwarded

> There are no Apple emojis on Windows. But as I tested, they work.
Yes, I mean apple by default

> maybe rewinding occurs on similar fragments?
No, i recorded a video with sound with 3 different bugs

Added to the channel https://t.me/hawk1414

I clearly see second scrollbar

scroll works awful when mouse cursor is not on screen center. This problem is actual for "native scroll" and custom scroll.

no error on message sending fail

this button doesn't work

messages from users with whom you do not have a dialogue are not displayed

new group creation doesn't work

contacts are not working

archive tab doesn't work, archive chats are displayed in main dialog list

Polls doesn't work correct

counter doesn't work, if you have already read the message

you cant pick country and it's not autodecteting, so it's impossible to log in