diff --git a/src/components/chat/bubbles.ts b/src/components/chat/bubbles.ts
index e0fd7cc2..671e0f3e 100644
--- a/src/components/chat/bubbles.ts
+++ b/src/components/chat/bubbles.ts
@@ -130,6 +130,8 @@ export default class ChatBubbles {
   public isFirstLoad = true;
   private needReflowScroll: boolean;
 
+  private fetchNewPromise: Promise<void>;
+
   constructor(private chat: Chat, private appMessagesManager: AppMessagesManager, private appStickersManager: AppStickersManager, private appUsersManager: AppUsersManager, private appInlineBotsManager: AppInlineBotsManager, private appPhotosManager: AppPhotosManager, private appDocsManager: AppDocsManager, private appPeersManager: AppPeersManager, private appChatsManager: AppChatsManager, private storage: typeof sessionStorage) {
     //this.chat.log.error('Bubbles construction');
     
@@ -1399,6 +1401,7 @@ export default class ChatBubbles {
     this.messagesQueuePromise = null;
 
     this.getHistoryTopPromise = this.getHistoryBottomPromise = undefined;
+    this.fetchNewPromise = undefined;
 
     if(this.stickyIntersector) {
       this.stickyIntersector.disconnect();
@@ -1618,8 +1621,7 @@ export default class ChatBubbles {
 
       this.chat.dispatchEvent('setPeer', lastMsgId, !isJump);
 
-      const isFetchIntervalNeeded = () => peerId < 0 && !this.appChatsManager.isInChat(peerId) && false;
-      const needFetchInterval = isFetchIntervalNeeded();
+      const needFetchInterval = this.appMessagesManager.isFetchIntervalNeeded(peerId);
       const needFetchNew = savedPosition || needFetchInterval;
       if(!needFetchNew) {
         // warning
@@ -1627,20 +1629,44 @@ export default class ChatBubbles {
           this.scrollable.loadedAll.bottom = true;
         }
       } else {
+        const middleware = this.getMiddleware();
         Promise.all([setPeerPromise, getHeavyAnimationPromise()]).then(() => {
+          if(!middleware()) {
+            return;
+          }
+
           this.scrollable.checkForTriggers();
 
           if(needFetchInterval) {
-            const middleware = this.getMiddleware();
-            const interval = window.setInterval(() => {
-              if(!middleware() || !isFetchIntervalNeeded()) {
-                clearInterval(interval);
-                return;
-              }
-
-              this.scrollable.loadedAll.bottom = false;
-              this.loadMoreHistory(false);
-            }, 30e3);
+            const f = () => {
+              this.fetchNewPromise = new Promise<void>((resolve) => {
+                if(!middleware() || !this.appMessagesManager.isFetchIntervalNeeded(peerId)) {
+                  resolve();
+                  return;
+                }
+  
+                this.appMessagesManager.getNewHistory(peerId, this.chat.threadId).then((historyStorage) => {
+                  if(!middleware()) {
+                    resolve();
+                    return;
+                  }
+  
+                  const slice = historyStorage.history.slice;
+                  const isBottomEnd = slice.isEnd(SliceEnd.Bottom);
+                  if(this.scrollable.loadedAll.bottom !== isBottomEnd) {
+                    this.scrollable.loadedAll.bottom = isBottomEnd;
+                    this.onScroll();
+                  }
+
+                  setTimeout(f, 30e3);
+                  resolve();
+                });
+              }).finally(() => {
+                this.fetchNewPromise = undefined;
+              });
+            };
+            
+            f();
           }
         });
       }
@@ -2626,9 +2652,15 @@ export default class ChatBubbles {
     } */
 
     const historyStorage = this.appMessagesManager.getHistoryStorage(this.peerId, this.chat.threadId);
-    if(history.includes(historyStorage.maxId)) {
+    const firstSlice = historyStorage.history.first;
+    const lastSlice = historyStorage.history.last;
+    if(firstSlice.isEnd(SliceEnd.Bottom) && history.includes(firstSlice[0])) {
       this.scrollable.loadedAll.bottom = true;
     }
+    
+    if(lastSlice.isEnd(SliceEnd.Top) && history.includes(lastSlice[lastSlice.length - 1])) {
+      this.scrollable.loadedAll.top = true;
+    }
 
     //console.time('appImManager render history');
 
@@ -2818,8 +2850,9 @@ export default class ChatBubbles {
         additionMsgIds = [additionMsgId];
       } else {
         const historyStorage = this.appMessagesManager.getHistoryStorage(peerId, this.chat.threadId);
-        if(historyStorage.history.length < loadCount && !historyStorage.history.slice.isEnd(SliceEnd.Both)) {
-          additionMsgIds = historyStorage.history.slice.slice();
+        const slice = historyStorage.history.slice;
+        if(slice.length < loadCount && !slice.isEnd(SliceEnd.Both)) {
+          additionMsgIds = slice.slice();
 
           // * filter last album, because we don't know is it the last item
           for(let i = additionMsgIds.length - 1; i >= 0; --i) {
diff --git a/src/helpers/slicedArray.ts b/src/helpers/slicedArray.ts
index 5ec02dba..807be1d7 100644
--- a/src/helpers/slicedArray.ts
+++ b/src/helpers/slicedArray.ts
@@ -4,6 +4,8 @@
  * https://github.com/morethanwords/tweb/blob/master/LICENSE
  */
 
+import { MOUNT_CLASS_TO } from "../config/debug";
+
 /**
  * Descend sorted storage
  */
@@ -14,15 +16,19 @@ export enum SliceEnd {
   None = 0,
   Top = 1,
   Bottom = 2,
-  Both = 4
+  Both = SliceEnd.Top | SliceEnd.Bottom
 };
 
 export interface Slice extends Array<ItemType> {
-  slicedArray: SlicedArray;
+  //slicedArray: SlicedArray;
   end: SliceEnd;
 
   isEnd: (side: SliceEnd) => boolean;
   setEnd: (side: SliceEnd) => void;
+  unsetEnd: (side: SliceEnd) => void;
+
+  slice: (from?: number, to?: number) => Slice;
+  splice: (start: number, deleteCount: number, ...items: ItemType[]) => Slice;
 }
 
 export interface SliceConstructor {
@@ -35,51 +41,84 @@ export default class SlicedArray {
   private sliceConstructor: SliceConstructor;
   
   constructor() {
-    const self = this;
-    this.sliceConstructor = class Slice extends Array<ItemType> implements Slice {
-      slicedArray: SlicedArray;
-      end: SliceEnd = SliceEnd.None;
+    // @ts-ignore
+    this.sliceConstructor = SlicedArray.getSliceConstructor(this);
 
-      constructor(...items: ItemType[]) {
-        super(...items);
-        this.slicedArray = self;
-      }
+    const first = this.constructSlice();
+    //first.setEnd(SliceEnd.Bottom);
+    this.slices = [first];
+  }
 
-      isEnd(side: SliceEnd) {
-        if(this.end & side) {
+  private static getSliceConstructor(slicedArray: SlicedArray) {
+    return class Slice extends Array<ItemType> implements Slice {
+      //slicedArray: SlicedArray;
+      end: SliceEnd = SliceEnd.None;
+  
+      /* constructor(...items: ItemType[]) {
+        super(...items);
+        //this.slicedArray = slicedArray;
+      } */
+  
+      isEnd(side: SliceEnd): boolean {
+        if((this.end & side) === side) {
           return true;
-        }
-
+        }/*  else if(!this.slicedArray) {
+          return false;
+        } */
+  
+        let isEnd = false;
         if(side === SliceEnd.Top) {
-          const slice = self.last;
-          return slice.end & side ? this.includes(slice[slice.length - 1]) || !slice.length : false;
+          const slice = slicedArray.last;
+          isEnd = slice.end & side ? this.includes(slice[slice.length - 1])/*  || !slice.length */ : false;
         } else if(side === SliceEnd.Bottom) {
-          const slice = self.first;
-          return slice.end & side ? this.includes(slice[0]) || !slice.length : false;
-        }/*  else if(side === SliceEnd.Both) {
-
-        } */
+          const slice = slicedArray.first;
+          isEnd = slice.end & side ? this.includes(slice[0])/*  || !slice.length */ : false;
+        } else if(side === SliceEnd.Both) {
+          return this.isEnd(SliceEnd.Top) && this.isEnd(SliceEnd.Bottom);
+        }
 
-        return false;
+        if(isEnd) {
+          this.setEnd(side);
+        }
+  
+        return isEnd;
       }
-
+  
       setEnd(side: SliceEnd) {
         this.end |= side;
+      }
 
-        if(side !== SliceEnd.Both && this.end & SliceEnd.Top && this.end & SliceEnd.Bottom) {
-          this.end |= SliceEnd.Both;
+      unsetEnd(side: SliceEnd) {
+        this.end ^= side;
+      }
+
+      splice(start: number, deleteCount: number, ...items: ItemType[]) {
+        const ret = super.splice(start, deleteCount, ...items);
+
+        if(!this.length) {
+          const slices = slicedArray.slices as number[][];
+          const idx = slices.indexOf(this);
+          if(idx !== -1) {
+            if(slices.length === 1) { // left empty slice without ends
+              this.unsetEnd(SliceEnd.Both);
+            } else { // delete this slice
+              slices.splice(idx, 1);
+            }
+          }
         }
+
+        return ret;
       }
     }
-
-    const first = this.constructSlice();
-    first.setEnd(SliceEnd.Bottom);
-    this.slices = [first];
   }
 
   public constructSlice(...items: ItemType[]) {
     //const slice = new Slice(this, ...items);
-    const slice = new this.sliceConstructor(...items);
+    // can't pass items directly to constructor because first argument is length
+    const slice = new this.sliceConstructor(items.length);
+    for(let i = 0, length = items.length; i < length; ++i) {
+      slice[i] = items[i];
+    }
     return slice;
     
     // ! code below will slow execution in 15 times
@@ -128,7 +167,7 @@ export default class SlicedArray {
     */
   }
 
-  public insertSlice(slice: ItemType[]) {
+  public insertSlice(slice: ItemType[], flatten = true) {
     if(!slice.length) {
       return;
     }
@@ -136,15 +175,15 @@ export default class SlicedArray {
     const first = this.slices[0];
     if(!first.length) {
       first.push(...slice);
-      return;
+      return first;
     }
 
     const lowerBound = slice[slice.length - 1];
     const upperBound = slice[0];
 
-    let foundSlice: Slice, lowerIndex = -1, upperIndex = -1;
-    for(let i = 0; i < this.slices.length; ++i) {
-      foundSlice = this.slices[i];
+    let foundSlice: Slice, lowerIndex = -1, upperIndex = -1, foundSliceIndex = 0;
+    for(; foundSliceIndex < this.slices.length; ++foundSliceIndex) {
+      foundSlice = this.slices[foundSliceIndex];
       lowerIndex = foundSlice.indexOf(lowerBound);
       upperIndex = foundSlice.indexOf(upperBound);
       
@@ -173,29 +212,38 @@ export default class SlicedArray {
       }
 
       this.slices.splice(insertIndex, 0, this.constructSlice(...slice));
+      foundSliceIndex = insertIndex;
     }
 
-    this.flatten();
-  }
-
-  private flatten() {
-    if(this.slices.length < 2) {
-      return;
+    if(flatten) {
+      return this.flatten(foundSliceIndex);
     }
+  }
 
-    for(let i = 0, length = this.slices.length; i < (length - 1); ++i) {
-      const prevSlice = this.slices[i];
-      const nextSlice = this.slices[i + 1];
+  private flatten(foundSliceIndex: number) {
+    if(this.slices.length >= 2) {
+      for(let i = 0, length = this.slices.length; i < (length - 1); ++i) {
+        const prevSlice = this.slices[i];
+        const nextSlice = this.slices[i + 1];
+  
+        const upperIndex = prevSlice.indexOf(nextSlice[0]);
+        if(upperIndex !== -1) {
+          prevSlice.setEnd(nextSlice.end);
+          this.slices.splice(i + 1, 1);
 
-      const upperIndex = prevSlice.indexOf(nextSlice[0]);
-      if(upperIndex !== -1) {
-        prevSlice.setEnd(nextSlice.end);
-        this.slices.splice(i + 1, 1);
-        length--;
+          if(i < foundSliceIndex) {
+            --foundSliceIndex;
+          }
 
-        this.insertSlice(nextSlice);
+          --length; // respect array bounds
+          --i;      // repeat from the same place
+  
+          this.insertSlice(nextSlice, false);
+        }
       }
     }
+
+    return this.slices[foundSliceIndex];
   }
 
   // * 
@@ -217,7 +265,7 @@ export default class SlicedArray {
   }
 
   public findSlice(item: ItemType) {
-    for(let i = 0; i < this.slices.length; ++i) {
+    for(let i = 0, length = this.slices.length; i < length; ++i) {
       const slice = this.slices[i];
       const index = slice.indexOf(item);
       if(index !== -1) {
@@ -295,6 +343,8 @@ export default class SlicedArray {
     const topWasMeantToLoad = add_offset < 0 ? limit + add_offset : limit;
     const bottomWasMeantToLoad = Math.abs(add_offset);
 
+    // can use 'slice' here to check because if it's end, then 'sliced' is out of 'slice'
+    // useful when there is only 1 message in chat on its reopening
     const topFulfilled = (slice.length - sliceOffset) >= topWasMeantToLoad || (slice.isEnd(SliceEnd.Top) ? (sliced.setEnd(SliceEnd.Top), true) : false);
     const bottomFulfilled = (sliceOffset - bottomWasMeantToLoad) >= 0 || (slice.isEnd(SliceEnd.Bottom) ? (sliced.setEnd(SliceEnd.Bottom), true) : false);
 
@@ -308,19 +358,40 @@ export default class SlicedArray {
   }
 
   public unshift(...items: ItemType[]) {
-    this.first.unshift(...items);
+    let slice = this.first;
+    if(!slice.length) {
+      slice.setEnd(SliceEnd.Bottom);
+    } else if(!slice.isEnd(SliceEnd.Bottom)) {
+      slice = this.constructSlice();
+      slice.setEnd(SliceEnd.Bottom);
+      this.slices.unshift(slice);
+    }
+
+    slice.unshift(...items);
   }
 
   public push(...items: ItemType[]) {
-    this.last.push(...items);
+    let slice = this.last;
+    if(!slice.length) {
+      slice.setEnd(SliceEnd.Top);
+    } else if(!slice.isEnd(SliceEnd.Top)) {
+      slice = this.constructSlice();
+      slice.setEnd(SliceEnd.Top);
+      this.slices.push(slice);
+    }
+
+    slice.push(...items);
   }
 
   public delete(item: ItemType) {
     const found = this.findSlice(item);
     if(found) {
       found.slice.splice(found.index, 1);
+      return true;
     }
+
+    return false;
   }
 }
 
-(window as any).slicedArray = new SlicedArray();
+MOUNT_CLASS_TO && (MOUNT_CLASS_TO.SlicedArray = SlicedArray);
diff --git a/src/lib/appManagers/appImManager.ts b/src/lib/appManagers/appImManager.ts
index 0d22c8b1..bce20395 100644
--- a/src/lib/appManagers/appImManager.ts
+++ b/src/lib/appManagers/appImManager.ts
@@ -50,6 +50,7 @@ import { copy, getObjectKeysAndSort } from '../../helpers/object';
 import { getFilesFromEvent } from '../../helpers/files';
 import PeerTitle from '../../components/peerTitle';
 import PopupPeer from '../../components/popups/peer';
+import { SliceEnd } from '../../helpers/slicedArray';
 
 //console.log('appImManager included33!');
 
@@ -445,10 +446,11 @@ export class AppImManager {
         return;
       } else if(e.code === 'ArrowUp') {
         if(!chat.input.editMsgId && chat.input.isInputEmpty()) {
-          const history = appMessagesManager.getHistoryStorage(chat.peerId, chat.threadId);
-          if(history.history.length) {
+          const historyStorage = appMessagesManager.getHistoryStorage(chat.peerId, chat.threadId);
+          const slice = historyStorage.history.slice;
+          if(slice.isEnd(SliceEnd.Bottom) && slice.length) {
             let goodMid: number;
-            for(const mid of history.history.slice) {
+            for(const mid of slice) {
               const message = chat.getMessage(mid);
               const good = this.myId === chat.peerId ? message.fromId === this.myId : message.pFlags.out;
 
diff --git a/src/lib/appManagers/appMessagesManager.ts b/src/lib/appManagers/appMessagesManager.ts
index c31a3da6..5a09f187 100644
--- a/src/lib/appManagers/appMessagesManager.ts
+++ b/src/lib/appManagers/appMessagesManager.ts
@@ -14,7 +14,7 @@ import ProgressivePreloader from "../../components/preloader";
 import { CancellablePromise, deferredPromise } from "../../helpers/cancellablePromise";
 import { tsNow } from "../../helpers/date";
 import { createPosterForVideo } from "../../helpers/files";
-import { copy, defineNotNumerableProperties, getObjectKeysAndSort } from "../../helpers/object";
+import { copy, getObjectKeysAndSort } from "../../helpers/object";
 import { randomLong } from "../../helpers/random";
 import { splitStringByLength, limitSymbols, escapeRegExp } from "../../helpers/string";
 import { Chat, ChatFull, Dialog as MTDialog, DialogPeer, DocumentAttribute, InputMedia, InputMessage, InputPeerNotifySettings, InputSingleMedia, Message, MessageAction, MessageEntity, MessageFwdHeader, MessageMedia, MessageReplies, MessageReplyHeader, MessagesDialogs, MessagesFilter, MessagesMessages, MethodDeclMap, NotifyPeer, PeerNotifySettings, PhotoSize, SendMessageAction, Update, Photo } from "../../layer";
@@ -168,7 +168,7 @@ export class AppMessagesManager {
   public migratedFromTo: {[peerId: number]: number} = {};
   public migratedToFrom: {[peerId: number]: number} = {};
 
-  public newMessagesHandlePromise = 0;
+  public newMessagesHandleTimeout = 0;
   public newMessagesToHandle: {[peerId: string]: Set<number>} = {};
   public newDialogsHandlePromise: Promise<any>;
   public newDialogsToHandle: {[peerId: string]: Dialog} = {};
@@ -1301,14 +1301,17 @@ export class AppMessagesManager {
       /* if(options.threadId && this.threadsStorage[peerId]) {
         delete this.threadsStorage[peerId][options.threadId];
       } */
-      if(options.threadId) {
-        const historyStorage = this.getHistoryStorage(peerId, options.threadId);
-        historyStorage.history.unshift(messageId);
+      const storages: HistoryStorage[] = [
+        this.getHistoryStorage(peerId),
+        options.threadId ? this.getHistoryStorage(peerId, options.threadId) : undefined
+      ];
+
+      for(const storage of storages) {
+        if(storage) {
+          storage.history.unshift(messageId);
+        }
       }
 
-      const historyStorage = this.getHistoryStorage(peerId);
-      historyStorage.history.unshift(messageId);
-
       //if(!options.isGroupedItem) {
       this.saveMessages([message], {storage, isOutgoing: true});
       setTimeout(() => {
@@ -1514,7 +1517,6 @@ export class AppMessagesManager {
     if(pendingData) {
       const {peerId, tempId, storage} = pendingData;
       const historyStorage = this.getHistoryStorage(peerId);
-      const pos = historyStorage.history.findSlice(tempId);
 
       apiUpdatesManager.processUpdateMessage({
         _: 'updateShort',
@@ -1524,9 +1526,7 @@ export class AppMessagesManager {
         }
       });
 
-      if(pos) {
-        pos.slice.splice(pos.index, 1);
-      }
+      historyStorage.history.delete(tempId);
 
       delete this.pendingByRandomId[randomId];
       delete storage[tempId];
@@ -1627,7 +1627,7 @@ export class AppMessagesManager {
     // ! ВНИМАНИЕ: ОЧЕНЬ СЛОЖНАЯ ЛОГИКА:
     // ! если делать запрос сначала по папке 0, потом по папке 1, по индексу 0 в массиве будет один и тот же диалог, с dialog.pFlags.pinned, ЛОЛ???
     // ! т.е., с запросом folder_id: 1, и exclude_pinned: 0, в результате будут ещё и закреплённые с папки 0
-    return apiManager.invokeApi('messages.getDialogs', {
+    return apiManager.invokeApiSingle('messages.getDialogs', {
       folder_id: folderId,
       offset_date: offsetDate,
       offset_id: offsetId,
@@ -3271,7 +3271,7 @@ export class AppMessagesManager {
   } 
 
   public getDiscussionMessage(peerId: number, mid: number) {
-    return apiManager.invokeApi('messages.getDiscussionMessage', {
+    return apiManager.invokeApiSingle('messages.getDiscussionMessage', {
       peer: appPeersManager.getInputPeerById(peerId),
       msg_id: this.getServerMessageId(mid)
     }).then(result => {
@@ -3295,9 +3295,20 @@ export class AppMessagesManager {
     });
   }
 
+  private handleNewMessage(peerId: number, mid: number) {
+    if(this.newMessagesToHandle[peerId] === undefined) {
+      this.newMessagesToHandle[peerId] = new Set();
+    }
+
+    this.newMessagesToHandle[peerId].add(mid);
+    if(!this.newMessagesHandleTimeout) {
+      this.newMessagesHandleTimeout = window.setTimeout(this.handleNewMessages, 0);
+    }
+  }
+
   handleNewMessages = () => {
-    clearTimeout(this.newMessagesHandlePromise);
-    this.newMessagesHandlePromise = 0;
+    clearTimeout(this.newMessagesHandleTimeout);
+    this.newMessagesHandleTimeout = 0;
 
     rootScope.broadcast('history_multiappend', this.newMessagesToHandle);
     this.newMessagesToHandle = {};
@@ -3404,6 +3415,7 @@ export class AppMessagesManager {
     return promise;
   }
 
+  // TODO: cancel notification by peer when this function is being called
   public readHistory(peerId: number, maxId = 0, threadId?: number, force = false) {
     //return Promise.resolve();
     // console.trace('start read')
@@ -3452,7 +3464,7 @@ export class AppMessagesManager {
           _: 'updateReadChannelInbox',
           max_id: maxId,
           channel_id: -peerId
-        }
+        } as Update.updateReadChannelInbox
       });
     } else {
       if(!historyStorage.readPromise) {
@@ -3477,21 +3489,10 @@ export class AppMessagesManager {
           _: 'updateReadHistoryInbox',
           max_id: maxId,
           peer: appPeersManager.getOutputPeer(peerId)
-        }
+        } as Update.updateReadHistoryInbox
       });
     }
 
-    if(!threadId && historyStorage && historyStorage.history.length) {
-      const slice = historyStorage.history.slice;
-      for(const mid of slice) {
-        const message = this.getMessageByPeer(peerId, mid);
-        if(message && !message.pFlags.out) {
-          message.pFlags.unread = false;
-          appNotificationsManager.cancel('msg' + mid);
-        }
-      }
-    }
-
     appNotificationsManager.soundReset(appPeersManager.getPeerString(peerId));
 
     if(historyStorage.readPromise) {
@@ -3534,7 +3535,7 @@ export class AppMessagesManager {
             _: 'updateChannelReadMessagesContents',
             channel_id: channelId,
             messages: msgIds
-          }
+          } as Update.updateChannelReadMessagesContents
         });
       });
     } else {
@@ -3548,7 +3549,7 @@ export class AppMessagesManager {
             messages: msgIds,
             pts: affectedMessages.pts,
             pts_count: affectedMessages.pts_count
-          }
+          } as Update.updateReadMessagesContents
         });
       });
     }
@@ -3694,15 +3695,8 @@ export class AppMessagesManager {
       return false;
     }
 
-    const history = historyStorage.history.slice;
-    const topMsgId = history[0];
-    history.unshift(message.mid);
-    if(message.mid < topMsgId) {
-      //this.log.error('this should\'nt have happenned!', message, history);
-      history.sort((a, b) => {
-        return b - a;
-      });
-    }
+    const slice = historyStorage.history.insertSlice([message.mid]);
+    slice.setEnd(SliceEnd.Bottom);
 
     if(historyStorage.count !== null) {
       historyStorage.count++;
@@ -3717,14 +3711,7 @@ export class AppMessagesManager {
     }
 
     if(!pendingMessage) {
-      if(this.newMessagesToHandle[peerId] === undefined) {
-        this.newMessagesToHandle[peerId] = new Set();
-      }
-
-      this.newMessagesToHandle[peerId].add(message.mid);
-      if(!this.newMessagesHandlePromise) {
-        this.newMessagesHandlePromise = window.setTimeout(this.handleNewMessages, 0);
-      }
+      this.handleNewMessage(peerId, message.mid);
     }
 
     if(isLocalThreadUpdate) {
@@ -4471,7 +4458,7 @@ export class AppMessagesManager {
       return Promise.resolve(Object.keys(storage).map(id => +id));
     }
 
-    return apiManager.invokeApi('messages.getScheduledHistory', {
+    return apiManager.invokeApiSingle('messages.getScheduledHistory', {
       peer: appPeersManager.getInputPeerById(peerId),
       hash: 0
     }).then(historyResult => {
@@ -4506,6 +4493,36 @@ export class AppMessagesManager {
     });
   }
 
+  public isFetchIntervalNeeded(peerId: number) {
+    return peerId < 0 && !appChatsManager.isInChat(peerId);
+  }
+
+  public async getNewHistory(peerId: number, threadId?: number) {
+    if(!this.isFetchIntervalNeeded(peerId)) {
+      return;
+    }
+
+    const historyStorage = this.getHistoryStorage(peerId, threadId);
+    const slice = historyStorage.history.slice;
+    if(!slice.isEnd(SliceEnd.Bottom)) {
+      return;
+    }
+
+    delete historyStorage.maxId;
+    slice.unsetEnd(SliceEnd.Bottom);
+
+    let historyResult = this.getHistory(peerId, slice[0], 0, 50, threadId);
+    if(historyResult instanceof Promise) {
+      historyResult = await historyResult;
+    }
+
+    for(let i = 0, length = historyResult.history.length; i < length; ++i) {
+      this.handleNewMessage(peerId, historyResult.history[i]);
+    }
+
+    return historyStorage;
+  }
+
   /**
    * * https://core.telegram.org/api/offsets, offset_id is inclusive
    */
@@ -4567,7 +4584,7 @@ export class AppMessagesManager {
     }
 
     const haveSlice = historyStorage.history.sliceMe(maxId, offset, limit);
-    if(haveSlice && (haveSlice.slice.length === limit || (haveSlice.fulfilled & SliceEnd.Both))) {
+    if(haveSlice && (haveSlice.slice.length === limit || (haveSlice.fulfilled & SliceEnd.Both) === SliceEnd.Both)) {
       return {
         count: historyStorage.count,
         history: haveSlice.slice,
@@ -4587,10 +4604,15 @@ export class AppMessagesManager {
 
   public fillHistoryStorage(peerId: number, offset_id: number, limit: number, add_offset: number, historyStorage: HistoryStorage, threadId?: number): Promise<void> {
     return this.requestHistory(peerId, offset_id, limit, add_offset, undefined, threadId).then((historyResult) => {
-      historyStorage.count = (historyResult as MessagesMessages.messagesMessagesSlice).count || historyResult.messages.length;
+      const {offset_id_offset, count, messages} = historyResult as MessagesMessages.messagesMessagesSlice;
 
-      const offsetIdOffset = (historyResult as MessagesMessages.messagesMessagesSlice).offset_id_offset || 0;
-      const isTopEnd = offsetIdOffset >= (historyStorage.count - limit) || historyStorage.count < (limit + add_offset);
+      historyStorage.count = count || messages.length;
+      const offsetIdOffset = offset_id_offset || 0;
+
+      const topWasMeantToLoad = add_offset < 0 ? limit + add_offset : limit;
+
+      const isTopEnd = offsetIdOffset >= (historyStorage.count - topWasMeantToLoad) || historyStorage.count < topWasMeantToLoad;
+      const isBottomEnd = !offsetIdOffset || (add_offset < 0 && (offsetIdOffset + add_offset) <= 0);
 
       /* if(!maxId && historyResult.messages.length) {
         maxId = this.incrementMessageId((historyResult.messages[0] as MyMessage).mid, 1);
@@ -4598,13 +4620,14 @@ export class AppMessagesManager {
 
       const wasTotalCount = historyStorage.history.length; */
 
-      historyResult.messages.forEach((message) => {
+      const mids = messages.map((message) => {
         if(this.mergeReplyKeyboard(historyStorage, message)) {
           rootScope.broadcast('history_reply_markup', {peerId});
         }
+
+        return (message as MyMessage).mid;
       });
 
-      const mids = historyResult.messages.map((message) => (message as MyMessage).mid);
       // * add bound manually. 
       // * offset_id will be inclusive only if there is 'add_offset' <= -1 (-1 - will only include the 'offset_id')
       if(offset_id && !mids.includes(offset_id) && offsetIdOffset < historyStorage.count) {
@@ -4618,10 +4641,16 @@ export class AppMessagesManager {
         mids.splice(i, 0, offset_id);
       }
       
-      historyStorage.history.insertSlice(mids);
-
-      if(isTopEnd) {
-        historyStorage.history.last.setEnd(SliceEnd.Top);
+      const slice = historyStorage.history.insertSlice(mids);
+      if(slice) {
+        if(isTopEnd) {
+          slice.setEnd(SliceEnd.Top);
+        }
+  
+        if(isBottomEnd) {
+          slice.setEnd(SliceEnd.Bottom);
+          historyStorage.maxId = slice[0]; // ! WARNING
+        }
       }
       
       /* const isBackLimit = offset < 0 && -offset !== fullLimit;
@@ -4681,7 +4710,7 @@ export class AppMessagesManager {
       options.msg_id = this.getServerMessageId(threadId) || 0;
     }
 
-    const promise: ReturnType<AppMessagesManager['requestHistory']> = apiManager.invokeApi(threadId ? 'messages.getReplies' : 'messages.getHistory', options, {
+    const promise: ReturnType<AppMessagesManager['requestHistory']> = apiManager.invokeApiSingle(threadId ? 'messages.getReplies' : 'messages.getHistory', options, {
       //timeout: APITIMEOUT,
       noErrorBox: true
     }) as any;
@@ -4699,21 +4728,24 @@ export class AppMessagesManager {
         apiUpdatesManager.addChannelState(-peerId, (historyResult as MessagesMessages.messagesChannelMessages).pts);
       }
 
-      let length = historyResult.messages.length;
+      let length = historyResult.messages.length, count = (historyResult as MessagesMessages.messagesMessagesSlice).count;
       if(length && historyResult.messages[length - 1].deleted) {
         historyResult.messages.splice(length - 1, 1);
         length--;
-        (historyResult as MessagesMessages.messagesMessagesSlice).count--;
+        count--;
       }
 
       // will load more history if last message is album grouped (because it can be not last item)
-      const historyStorage = this.getHistoryStorage(peerId, threadId);
       // historyResult.messages: desc sorted
-      if(length && (historyResult.messages[length - 1] as Message.message).grouped_id 
-        && (historyStorage.history.length + historyResult.messages.length) < (historyResult as MessagesMessages.messagesMessagesSlice).count) {
-        return this.requestHistory(peerId, (historyResult.messages[length - 1] as Message.message).mid, 10, 0, offsetDate, threadId).then((_historyResult) => {
-          return historyResult;
-        });
+      const historyStorage = this.getHistoryStorage(peerId, threadId);
+      const oldestMessage: Message.message = historyResult.messages[length - 1] as any;
+      if(length && oldestMessage.grouped_id) {
+        const foundSlice = historyStorage.history.findSlice(oldestMessage.mid);
+        if(foundSlice && (foundSlice.slice.length + historyResult.messages.length) < count) {
+          return this.requestHistory(peerId, oldestMessage.mid, 10, 0, offsetDate, threadId).then((_historyResult) => {
+            return historyResult;
+          });
+        }
       }
 
       return historyResult;
@@ -4760,12 +4792,12 @@ export class AppMessagesManager {
     
           let promise: Promise<MethodDeclMap['channels.getMessages']['res'] | MethodDeclMap['messages.getMessages']['res']>;
           if(+peerId < 0 && appPeersManager.isChannel(+peerId)) {
-            promise = apiManager.invokeApi('channels.getMessages', {
+            promise = apiManager.invokeApiSingle('channels.getMessages', {
               channel: appChatsManager.getChannelInput(-+peerId),
               id: msgIds
             });
           } else {
-            promise = apiManager.invokeApi('messages.getMessages', {
+            promise = apiManager.invokeApiSingle('messages.getMessages', {
               id: msgIds
             });
           }
diff --git a/src/lib/appManagers/appPhotosManager.ts b/src/lib/appManagers/appPhotosManager.ts
index 7f420204..2e47153b 100644
--- a/src/lib/appManagers/appPhotosManager.ts
+++ b/src/lib/appManagers/appPhotosManager.ts
@@ -13,7 +13,7 @@ import type { DownloadOptions } from "../mtproto/apiFileManager";
 import { bytesFromHex } from "../../helpers/bytes";
 import { CancellablePromise } from "../../helpers/cancellablePromise";
 import { getFileNameByLocation } from "../../helpers/fileName";
-import { safeReplaceArrayInObject, defineNotNumerableProperties, isObject } from "../../helpers/object";
+import { safeReplaceArrayInObject, isObject } from "../../helpers/object";
 import { isSafari } from "../../helpers/userAgent";
 import { InputFileLocation, InputMedia, Photo, PhotoSize, PhotosPhotos } from "../../layer";
 import apiManager from "../mtproto/mtprotoworker";
diff --git a/src/lib/storages/dialogs.ts b/src/lib/storages/dialogs.ts
index 7fe9735f..dc2a20a5 100644
--- a/src/lib/storages/dialogs.ts
+++ b/src/lib/storages/dialogs.ts
@@ -25,6 +25,7 @@ import { forEachReverse, insertInDescendSortedArray } from "../../helpers/array"
 import rootScope from "../rootScope";
 import { safeReplaceObject } from "../../helpers/object";
 import { AppStateManager } from "../appManagers/appStateManager";
+import { SliceEnd } from "../../helpers/slicedArray";
 
 export default class DialogsStorage {
   private storage: AppStateManager['storages']['dialogs'];
@@ -490,13 +491,17 @@ export default class DialogsStorage {
     }
 
     const historyStorage = this.appMessagesManager.getHistoryStorage(peerId);
+    const slice = historyStorage.history.slice;
     /* if(historyStorage === undefined) { // warning
       historyStorage.history.push(mid);
       if(this.mergeReplyKeyboard(historyStorage, message)) {
         rootScope.broadcast('history_reply_markup', {peerId});
       }
-    } else  */if(!historyStorage.history.slice.length) {
+    } else  */if(!slice.length) {
       historyStorage.history.unshift(mid);
+    } else if(!slice.isEnd(SliceEnd.Bottom)) { // * this will probably never happen, however, if it does, then it will fix slice with top_message
+      const slice = historyStorage.history.insertSlice([mid]);
+      slice.setEnd(SliceEnd.Bottom);
     }
 
     historyStorage.maxId = mid;
diff --git a/src/tests/slicedArray.test.ts b/src/tests/slicedArray.test.ts
new file mode 100644
index 00000000..b5a399bb
--- /dev/null
+++ b/src/tests/slicedArray.test.ts
@@ -0,0 +1,121 @@
+import SlicedArray, { Slice } from "../helpers/slicedArray";
+
+test('Slicing returns new Slice', () => {
+  const sliced = new SlicedArray();
+  const newSlice = sliced.slice.slice();
+  expect(newSlice.isEnd).toBeDefined();
+});
+
+describe('Inserting', () => {
+  const sliced = new SlicedArray();
+
+  // @ts-ignore
+  const slices = sliced.slices;
+    
+  const arr = [100, 99, 98, 97, 96, 95];
+  const distantArr = arr.slice(-2).map(v => v - 2);
+  const missingArr = [arr[arr.length - 1], arr[arr.length - 1] - 1, distantArr[0]];
+
+  const startValue = 90;
+  const values: number[] = [];
+  const valuesPerArray = 3;
+  const totalArrays = 10;
+  for(let i = 0, length = valuesPerArray * totalArrays; i < length; ++i) {
+    values.push(startValue - i);
+  }
+  const arrays: number[][] = [];
+  for(let i = 0; i < totalArrays; ++i) {
+    arrays.push(values.slice(valuesPerArray * i, valuesPerArray * (i + 1)));
+  }
+
+  test('Insert & flatten', () => {
+    const idx = 2;
+  
+    sliced.insertSlice(arr.slice(0, idx + 1));
+    sliced.insertSlice(arr.slice(idx));
+  
+    expect([...sliced.first]).toEqual(arr);
+  });
+
+  test('Insert inner values', () => {
+    sliced.insertSlice(arr.slice(1, -1));
+
+    expect([...sliced.first]).toEqual(arr);
+  });
+
+  test('Insert distant slice', () => {
+    const length = slices.length;
+    sliced.insertSlice(distantArr);
+
+    expect(slices.length).toEqual(length + 1);
+  });
+
+  test('Insert intersection & join them', () => {
+    const length = slices.length;
+    sliced.insertSlice(missingArr);
+
+    expect(slices.length).toEqual(length - 1);
+  });
+
+  let returnedSlice: Slice;
+  test('Insert arrays with gap & join them', () => {
+    slices[0].length = 0;
+
+    for(const arr of arrays) {
+      sliced.insertSlice(arr);
+    }
+
+    expect(slices.length).toEqual(totalArrays);
+
+    returnedSlice = sliced.insertSlice(values.slice(0, -valuesPerArray + 1));
+
+    expect(slices.length).toEqual(1);
+  });
+
+  test('Return inserted & flattened slice', () => {
+    expect(slices[0]).toEqual(returnedSlice);
+  });
+});
+
+describe('Slicing', () => {
+  const sliced = new SlicedArray();
+
+  // @ts-ignore
+  const slices = sliced.slices;
+
+  const VALUES_LENGTH = 100;
+  const INCREMENTOR = 0xFFFF;
+  const values: number[] = [];
+  for(let i = 0; i < VALUES_LENGTH; ++i) {
+    values[i] = i + INCREMENTOR * i;
+  }
+  values.sort((a, b) => b - a);
+  sliced.insertSlice(values);
+
+  const addOffset = 40;
+  const limit = 40;
+
+  const r = (func: (idx: number) => void) => {
+    const max = VALUES_LENGTH * 3;
+    for(let i = 0; i < max; ++i) {
+      const idx = Math.random() * max | 0;
+      func(idx);
+    }
+  };
+
+  describe('Positive addOffset', () => {
+    test('From the start', () => {
+      const {slice} = sliced.sliceMe(0, addOffset, limit);
+      expect([...slice]).toEqual(values.slice(addOffset, addOffset + limit));
+    });
+  
+    test('From existing offsetId', () => {
+      r((idx) => {
+        const value = values[idx] || 1;
+        idx += 1; // because is it inclusive
+        const {slice} = sliced.sliceMe(value, addOffset, limit);
+        expect([...slice]).toEqual(values.slice(idx + addOffset, idx + addOffset + limit));
+      });
+    });
+  });
+});