diff --git a/models/chunter/src/index.ts b/models/chunter/src/index.ts
index 7be1cf5ec6..52a60cf306 100644
--- a/models/chunter/src/index.ts
+++ b/models/chunter/src/index.ts
@@ -194,6 +194,16 @@ export function createModel (builder: Builder, options = { addApplication: true
     getName: chunter.function.GetDmName
   })
 
+  builder.mixin(chunter.class.Message, core.class.Class, notification.mixin.TrackedDoc, {})
+  builder.mixin(chunter.class.Message, core.class.Class, notification.mixin.ClassCollaborators, {
+    fields: ['createdBy', 'replies']
+  })
+
+  builder.mixin(chunter.class.ChunterSpace, core.class.Class, notification.mixin.TrackedDoc, {})
+  builder.mixin(chunter.class.DirectMessage, core.class.Class, notification.mixin.ClassCollaborators, {
+    fields: ['members']
+  })
+
   builder.mixin(chunter.class.DirectMessage, core.class.Class, view.mixin.ObjectPresenter, {
     presenter: chunter.component.DmPresenter
   })
diff --git a/models/contact/package.json b/models/contact/package.json
index 54f76d5b6f..a79bcb7f5a 100644
--- a/models/contact/package.json
+++ b/models/contact/package.json
@@ -37,6 +37,7 @@
     "@hcengineering/ui": "^0.6.3",
     "@hcengineering/platform": "^0.6.8",
     "@hcengineering/contact": "^0.6.11",
+    "@hcengineering/notification": "^0.6.7",
     "@hcengineering/contact-resources": "^0.6.0",
     "@hcengineering/view": "^0.6.2",
     "cross-fetch": "^3.1.5",
diff --git a/models/contact/src/index.ts b/models/contact/src/index.ts
index d9ec0182e5..5dbb7ba47f 100644
--- a/models/contact/src/index.ts
+++ b/models/contact/src/index.ts
@@ -55,6 +55,7 @@ import workbench from '@hcengineering/model-workbench'
 import type { Asset, IntlString, Resource } from '@hcengineering/platform'
 import setting from '@hcengineering/setting'
 import { AnyComponent } from '@hcengineering/ui'
+import notification from '@hcengineering/notification'
 import templates from '@hcengineering/templates'
 import contact from './plugin'
 
@@ -313,6 +314,14 @@ export function createModel (builder: Builder): void {
     inlineEditor: contact.component.ContactArrayEditor
   })
 
+  builder.mixin(contact.class.Contact, core.class.Class, notification.mixin.TrackedDoc, {})
+
+  builder.mixin(contact.class.Channel, core.class.Class, notification.mixin.TrackedDoc, {})
+
+  builder.mixin(contact.class.Contact, core.class.Class, notification.mixin.ClassCollaborators, {
+    fields: []
+  })
+
   builder.mixin(contact.class.Member, core.class.Class, view.mixin.ObjectPresenter, {
     presenter: contact.component.MemberPresenter
   })
diff --git a/models/document/package.json b/models/document/package.json
index 996d743b32..93ecade677 100644
--- a/models/document/package.json
+++ b/models/document/package.json
@@ -36,6 +36,7 @@
     "@hcengineering/core": "^0.6.21",
     "@hcengineering/ui": "^0.6.3",
     "@hcengineering/platform": "^0.6.8",
+    "@hcengineering/notification": "^0.6.7",
     "@hcengineering/document": "^0.6.0",
     "@hcengineering/document-resources": "^0.6.0",
     "@hcengineering/view": "^0.6.2",
diff --git a/models/document/src/index.ts b/models/document/src/index.ts
index 820cc620cc..95aae9e2b5 100644
--- a/models/document/src/index.ts
+++ b/models/document/src/index.ts
@@ -46,6 +46,7 @@ import presentation from '@hcengineering/model-presentation'
 import view, { actionTemplates, createAction } from '@hcengineering/model-view'
 import workbench from '@hcengineering/model-workbench'
 import tags from '@hcengineering/tags'
+import notification from '@hcengineering/notification'
 import document from './plugin'
 
 export const DOMAIN_DOCUMENT = 'document' as Domain
@@ -182,6 +183,8 @@ export function createModel (builder: Builder): void {
     component: document.component.CreateDocument
   })
 
+  builder.mixin(document.class.Document, core.class.Class, notification.mixin.TrackedDoc, {})
+
   builder.mixin(document.class.Document, core.class.Class, view.mixin.ObjectPanel, {
     component: document.component.EditDoc
   })
diff --git a/models/inventory/src/index.ts b/models/inventory/src/index.ts
index a391dc7660..cea2561d7c 100644
--- a/models/inventory/src/index.ts
+++ b/models/inventory/src/index.ts
@@ -156,7 +156,7 @@ export function createModel (builder: Builder): void {
     inventory.category.Inventory
   )
 
-  builder.mixin(inventory.class.Product, core.class.Class, notification.mixin.LastViewAttached, {})
+  builder.mixin(inventory.class.Product, core.class.Class, notification.mixin.TrackedDoc, {})
 
   createAction(builder, {
     label: inventory.string.CreateSubcategory,
diff --git a/models/notification/src/index.ts b/models/notification/src/index.ts
index c1b5de82a9..a6d814f25c 100644
--- a/models/notification/src/index.ts
+++ b/models/notification/src/index.ts
@@ -14,14 +14,13 @@
 // limitations under the License.
 //
 
-import { Account, Doc, Domain, DOMAIN_MODEL, Ref, Timestamp, TxCUD } from '@hcengineering/core'
-import { ArrOf, Builder, Mixin, Model, Prop, TypeRef, TypeString, TypeTimestamp } from '@hcengineering/model'
+import { Account, Doc, Domain, DOMAIN_MODEL, IndexKind, Ref, TxCUD } from '@hcengineering/core'
+import { ArrOf, Builder, Index, Mixin, Model, Prop, TypeRef, TypeString, UX } from '@hcengineering/model'
 import core, { TAttachedDoc, TClass, TDoc } from '@hcengineering/model-core'
 import type {
   AnotherUserNotifications,
   EmailNotification,
   LastView,
-  LastViewAttached,
   Notification,
   NotificationProvider,
   NotificationSetting,
@@ -35,12 +34,10 @@ import notification from './plugin'
 
 export const DOMAIN_NOTIFICATION = 'notification' as Domain
 
-@Model(notification.class.LastView, core.class.AttachedDoc, DOMAIN_NOTIFICATION)
-export class TLastView extends TAttachedDoc implements LastView {
-  @Prop(TypeTimestamp(), notification.string.LastView)
-    lastView!: Timestamp
-
+@Model(notification.class.LastView, core.class.Doc, DOMAIN_NOTIFICATION)
+export class TLastView extends TDoc implements LastView {
   @Prop(TypeRef(core.class.Account), core.string.ModifiedBy)
+  @Index(IndexKind.Indexed)
     user!: Ref<Account>
 }
 
@@ -112,8 +109,20 @@ export class TAnotherUserNotifications extends TClass implements AnotherUserNoti
   fields!: string[]
 }
 
-@Mixin(notification.mixin.LastViewAttached, core.class.Class)
-export class TLastViewAttached extends TClass implements LastViewAttached {}
+@Mixin(notification.mixin.ClassCollaborators, core.class.Class)
+export class TClassCollaborators extends TClass {
+  fields!: string[]
+}
+
+@Mixin(notification.mixin.TrackedDoc, core.class.Class)
+export class TTrackedDoc extends TClass {}
+
+@Mixin(notification.mixin.Collaborators, core.class.Doc)
+@UX(notification.string.Collaborators)
+export class TCollaborators extends TDoc {
+  @Prop(ArrOf(TypeRef(core.class.Account)), notification.string.Collaborators)
+    collaborators!: Ref<Account>[]
+}
 
 export function createModel (builder: Builder): void {
   builder.createModel(
@@ -125,7 +134,9 @@ export function createModel (builder: Builder): void {
     TNotificationSetting,
     TSpaceLastEdit,
     TAnotherUserNotifications,
-    TLastViewAttached
+    TClassCollaborators,
+    TTrackedDoc,
+    TCollaborators
   )
 
   builder.createDoc(
@@ -155,24 +166,28 @@ export function createModel (builder: Builder): void {
   )
 
   builder.createDoc(
-    notification.class.NotificationProvider,
+    notification.class.NotificationType,
     core.space.Model,
     {
-      label: notification.string.PlatformNotification,
-      default: true
+      label: notification.string.Notification,
+      hidden: true,
+      textTemplate: '',
+      htmlTemplate: '',
+      subjectTemplate: ''
     },
-    notification.ids.PlatformNotification
+    notification.ids.CollaboratorNotification
   )
 
-  builder.createDoc(
-    notification.class.NotificationProvider,
-    core.space.Model,
-    {
-      label: notification.string.BrowserNotification,
-      default: true
-    },
-    notification.ids.BrowserNotification
-  )
+  // Temporarily disabled, we should think about it
+  // builder.createDoc(
+  //   notification.class.NotificationProvider,
+  //   core.space.Model,
+  //   {
+  //     label: notification.string.BrowserNotification,
+  //     default: true
+  //   },
+  //   notification.ids.BrowserNotification
+  // )
 
   builder.createDoc(
     notification.class.NotificationProvider,
diff --git a/models/notification/src/migration.ts b/models/notification/src/migration.ts
index e159ffedeb..2f92e3fec5 100644
--- a/models/notification/src/migration.ts
+++ b/models/notification/src/migration.ts
@@ -13,9 +13,21 @@
 // limitations under the License.
 //
 
-import core, { DOMAIN_TX, Ref, TxCreateDoc, TxOperations } from '@hcengineering/core'
+import core, {
+  Account,
+  AttachedDoc,
+  Class,
+  Doc,
+  DOMAIN_TX,
+  generateId,
+  Ref,
+  TxCollectionCUD,
+  TxCreateDoc,
+  TxOperations,
+  TxRemoveDoc
+} from '@hcengineering/core'
 import { MigrateOperation, MigrationClient, MigrationUpgradeClient } from '@hcengineering/model'
-import notification, { Notification, NotificationType } from '@hcengineering/notification'
+import notification, { LastView, Notification, NotificationType } from '@hcengineering/notification'
 import { DOMAIN_NOTIFICATION } from '.'
 
 async function fillNotificationText (client: MigrationClient): Promise<void> {
@@ -79,9 +91,104 @@ async function createSpace (client: MigrationUpgradeClient): Promise<void> {
   }
 }
 
+async function migrateLastView (client: MigrationClient): Promise<void> {
+  // lets clear last view txes (it should be derived and shouldn't store in tx collection)
+  const txes = await client.find(DOMAIN_TX, {
+    objectClass: notification.class.LastView
+  })
+  for (const tx of txes) {
+    await client.delete(DOMAIN_TX, tx._id)
+  }
+
+  const h = client.hierarchy
+  const docClasses = h.getDescendants(core.class.Doc)
+  const trackedClasses = docClasses.filter((p) => h.hasMixin(h.getClass(p), notification.mixin.TrackedDoc))
+  const allowedClasses = new Set<Ref<Class<Doc>>>()
+  trackedClasses.forEach((p) => h.getDescendants(p).forEach((a) => allowedClasses.add(a)))
+
+  const removeTxes = await client.find<TxRemoveDoc<Doc>>(
+    DOMAIN_TX,
+    {
+      _class: core.class.TxRemoveDoc
+    },
+    { projection: { objectId: 1 } }
+  )
+
+  const removedDocs: Set<Ref<Doc>> = new Set(removeTxes.map((p) => p.objectId))
+  const removedCollectionTxes = await client.find<TxCollectionCUD<Doc, AttachedDoc>>(
+    DOMAIN_TX,
+    {
+      _class: core.class.TxCollectionCUD,
+      'tx._class': core.class.TxRemoveDoc
+    },
+    { projection: { tx: 1 } }
+  )
+  removedCollectionTxes.forEach((p) => p.tx.objectId)
+
+  const newLastView: Map<Ref<Account>, LastView> = new Map()
+  let total = 0
+  while (true) {
+    const lastViews = await client.find<LastView>(
+      DOMAIN_NOTIFICATION,
+      {
+        _class: notification.class.LastView,
+        attachedTo: { $exists: true }
+      },
+      { limit: 10000 }
+    )
+    total += lastViews.length
+    console.log(`migrate ${total} notifications`)
+    if (lastViews.length === 0) break
+    for (const lastView of lastViews) {
+      if (
+        lastView.user !== core.account.System &&
+        allowedClasses.has(lastView.attachedToClass) &&
+        !removedDocs.has(lastView.attachedTo)
+      ) {
+        const obj: LastView = newLastView.get(lastView.user) ?? {
+          user: lastView.user,
+          modifiedBy: lastView.user,
+          modifiedOn: Date.now(),
+          _id: generateId(),
+          space: notification.space.Notifications,
+          _class: notification.class.LastView
+        }
+        obj[lastView.attachedTo] = lastView.lastView
+        newLastView.set(lastView.user, obj)
+      }
+    }
+    await Promise.all(lastViews.map((p) => client.delete(DOMAIN_NOTIFICATION, p._id)))
+  }
+  for (const [, lastView] of newLastView) {
+    await client.create(DOMAIN_NOTIFICATION, lastView)
+  }
+}
+
+async function fillCollaborators (client: MigrationClient): Promise<void> {
+  const targetClasses = await client.model.findAll(notification.mixin.ClassCollaborators, {})
+  for (const targetClass of targetClasses) {
+    const domain = client.hierarchy.getDomain(targetClass._id)
+    const desc = client.hierarchy.getDescendants(targetClass._id)
+    await client.update(
+      domain,
+      {
+        _class: { $in: desc },
+        'notification:mixin:Collaborators': { $exists: false }
+      },
+      {
+        'notification:mixin:Collaborators': {
+          collaborators: []
+        }
+      }
+    )
+  }
+}
+
 export const notificationOperation: MigrateOperation = {
   async migrate (client: MigrationClient): Promise<void> {
     await fillNotificationText(client)
+    await migrateLastView(client)
+    await fillCollaborators(client)
   },
   async upgrade (client: MigrationUpgradeClient): Promise<void> {
     await createSpace(client)
diff --git a/models/notification/src/plugin.ts b/models/notification/src/plugin.ts
index 6351df4170..0c79e0dfbc 100644
--- a/models/notification/src/plugin.ts
+++ b/models/notification/src/plugin.ts
@@ -26,7 +26,8 @@ export default mergeIds(notificationId, notification, {
     MentionNotification: '' as IntlString,
     PlatformNotification: '' as IntlString,
     BrowserNotification: '' as IntlString,
-    EmailNotification: '' as IntlString
+    EmailNotification: '' as IntlString,
+    Collaborators: '' as IntlString
   },
   component: {
     NotificationSettings: '' as AnyComponent
diff --git a/models/recruit/package.json b/models/recruit/package.json
index 967adcefb9..da503d9a4e 100644
--- a/models/recruit/package.json
+++ b/models/recruit/package.json
@@ -37,6 +37,7 @@
     "@hcengineering/recruit": "^0.6.7",
     "@hcengineering/recruit-resources": "^0.6.0",
     "@hcengineering/chunter": "^0.6.2",
+    "@hcengineering/notification": "^0.6.7",
     "@hcengineering/model-attachment": "^0.6.0",
     "@hcengineering/model-chunter": "^0.6.0",
     "@hcengineering/view": "^0.6.2",
diff --git a/models/recruit/src/index.ts b/models/recruit/src/index.ts
index 64166c7fce..56eb51d2c2 100644
--- a/models/recruit/src/index.ts
+++ b/models/recruit/src/index.ts
@@ -41,6 +41,7 @@ import presentation from '@hcengineering/model-presentation'
 import tags from '@hcengineering/model-tags'
 import task, { actionTemplates, DOMAIN_TASK, TSpaceWithStates, TTask } from '@hcengineering/model-task'
 import tracker from '@hcengineering/model-tracker'
+import notification from '@hcengineering/notification'
 import view, { actionTemplates as viewTemplates, createAction } from '@hcengineering/model-view'
 import workbench, { Application, createNavigateAction } from '@hcengineering/model-workbench'
 import { getEmbeddedLabel, IntlString } from '@hcengineering/platform'
@@ -211,6 +212,14 @@ export function createModel (builder: Builder): void {
     editor: recruit.component.VacancyList
   })
 
+  builder.mixin(recruit.class.Vacancy, core.class.Class, notification.mixin.ClassCollaborators, {
+    fields: ['createdBy']
+  })
+
+  builder.mixin(recruit.class.Applicant, core.class.Class, notification.mixin.ClassCollaborators, {
+    fields: ['createdBy']
+  })
+
   builder.mixin(recruit.mixin.Candidate, core.class.Mixin, view.mixin.ObjectFactory, {
     component: recruit.component.CreateCandidate
   })
@@ -603,6 +612,10 @@ export function createModel (builder: Builder): void {
     recruit.viewlet.ApplicantDashboard
   )
 
+  builder.mixin(recruit.class.Applicant, core.class.Class, notification.mixin.TrackedDoc, {})
+
+  builder.mixin(recruit.class.Vacancy, core.class.Class, notification.mixin.TrackedDoc, {})
+
   builder.mixin(recruit.class.Applicant, core.class.Class, task.mixin.KanbanCard, {
     card: recruit.component.KanbanCard
   })
diff --git a/models/server-notification/src/index.ts b/models/server-notification/src/index.ts
index af8f1d3307..ad67a93184 100644
--- a/models/server-notification/src/index.ts
+++ b/models/server-notification/src/index.ts
@@ -42,4 +42,16 @@ export function createModel (builder: Builder): void {
   builder.createDoc(serverCore.class.Trigger, core.space.Model, {
     trigger: serverNotification.trigger.UpdateLastView
   })
+
+  builder.createDoc(serverCore.class.Trigger, core.space.Model, {
+    trigger: serverNotification.trigger.CreateCollaboratorDoc
+  })
+
+  builder.createDoc(serverCore.class.Trigger, core.space.Model, {
+    trigger: serverNotification.trigger.UpdateCollaboratorDoc
+  })
+
+  builder.createDoc(serverCore.class.Trigger, core.space.Model, {
+    trigger: serverNotification.trigger.OnAddCollborator
+  })
 }
diff --git a/models/task/src/index.ts b/models/task/src/index.ts
index b6cd5bbe14..f27527a7cf 100644
--- a/models/task/src/index.ts
+++ b/models/task/src/index.ts
@@ -382,7 +382,7 @@ export function createModel (builder: Builder): void {
     editor: task.component.TaskHeader
   })
 
-  builder.mixin(task.class.Task, core.class.Class, notification.mixin.LastViewAttached, {})
+  builder.mixin(task.class.Task, core.class.Class, notification.mixin.TrackedDoc, {})
   builder.mixin(task.class.Task, core.class.Class, notification.mixin.AnotherUserNotifications, {
     fields: ['assignee']
   })
diff --git a/models/tracker/src/index.ts b/models/tracker/src/index.ts
index 11bb929846..9a641421f6 100644
--- a/models/tracker/src/index.ts
+++ b/models/tracker/src/index.ts
@@ -886,6 +886,10 @@ export function createModel (builder: Builder): void {
     presenter: tracker.component.PriorityPresenter
   })
 
+  builder.mixin(tracker.class.Issue, core.class.Class, notification.mixin.ClassCollaborators, {
+    fields: ['createdBy', 'assignee']
+  })
+
   builder.mixin(tracker.class.TypeIssuePriority, core.class.Class, view.mixin.AttributeFilter, {
     component: view.component.ValueFilter
   })
@@ -937,7 +941,8 @@ export function createModel (builder: Builder): void {
     inlineEditor: tracker.component.ComponentStatusEditor
   })
 
-  builder.mixin(tracker.class.Issue, core.class.Class, notification.mixin.LastViewAttached, {})
+  builder.mixin(tracker.class.Issue, core.class.Class, notification.mixin.TrackedDoc, {})
+
   builder.mixin(tracker.class.Issue, core.class.Class, notification.mixin.AnotherUserNotifications, {
     fields: ['assignee']
   })
diff --git a/packages/core/src/hierarchy.ts b/packages/core/src/hierarchy.ts
index e43fd9c126..9ee8a12ef4 100644
--- a/packages/core/src/hierarchy.ts
+++ b/packages/core/src/hierarchy.ts
@@ -74,6 +74,17 @@ export class Hierarchy {
     return typeof (d as any)[mixin] === 'object'
   }
 
+  classHierarchyMixin<D extends Doc, M extends D>(_class: Ref<Class<D>>, mixin: Ref<Mixin<M>>): M | undefined {
+    let clazz = this.getClass(_class)
+    while (true) {
+      if (this.hasMixin(clazz, mixin)) {
+        return this.as(clazz, mixin) as any as M
+      }
+      if (clazz.extends === undefined) return
+      clazz = this.getClass(clazz.extends)
+    }
+  }
+
   isMixin (_class: Ref<Class<Doc>>): boolean {
     const data = this.classifiers.get(_class)
     return data !== undefined && this._isMixin(data)
diff --git a/packages/core/src/operator.ts b/packages/core/src/operator.ts
index b6925505d9..2f4f5b3f1e 100644
--- a/packages/core/src/operator.ts
+++ b/packages/core/src/operator.ts
@@ -150,13 +150,24 @@ function $inc (document: Doc, keyval: Record<string, number>): void {
   }
 }
 
+function $unset (document: Doc, keyval: Record<string, PropertyType>): void {
+  const doc = document as any
+  for (const key in keyval) {
+    if (doc[key] !== undefined) {
+      // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
+      delete doc[key]
+    }
+  }
+}
+
 const operators: Record<string, _OperatorFunc> = {
   $push,
   $pull,
   $update,
   $move,
   $pushMixin,
-  $inc
+  $inc,
+  $unset
 }
 
 /**
diff --git a/packages/core/src/tx.ts b/packages/core/src/tx.ts
index a5d06d29ba..86d8e25fab 100644
--- a/packages/core/src/tx.ts
+++ b/packages/core/src/tx.ts
@@ -201,6 +201,20 @@ export interface PushOptions<T extends object> {
   $move?: Partial<OmitNever<ArrayMoveDescriptor<Required<T>>>>
 }
 
+/**
+ * @public
+ */
+export interface UnsetProperties {
+  [key: string]: any
+}
+
+/**
+ * @public
+ */
+export interface UnsetOptions {
+  $unset?: UnsetProperties
+}
+
 /**
  * @public
  */
diff --git a/packages/model/src/migration.ts b/packages/model/src/migration.ts
index 16a60aff6e..3c99b2fa76 100644
--- a/packages/model/src/migration.ts
+++ b/packages/model/src/migration.ts
@@ -1,5 +1,4 @@
 import {
-  ArrayAsElementPosition,
   Client,
   Doc,
   DocumentQuery,
@@ -9,25 +8,18 @@ import {
   IncOptions,
   ModelDb,
   ObjQueryType,
-  OmitNever,
   PushOptions,
-  Ref
+  Ref,
+  UnsetOptions
 } from '@hcengineering/core'
 
-/**
- * @public
- */
-export interface UnsetOptions<T extends object> {
-  $unset?: Partial<OmitNever<ArrayAsElementPosition<Required<T>>>>
-}
-
 /**
  * @public
  */
 export type MigrateUpdate<T extends Doc> = Partial<T> &
 Omit<PushOptions<T>, '$move'> &
 IncOptions<T> &
-UnsetOptions<T> & {
+UnsetOptions & {
   // For any other mongo stuff
   [key: string]: any
 }
diff --git a/packages/panel/package.json b/packages/panel/package.json
index 92f59ba186..4e3dcfc466 100644
--- a/packages/panel/package.json
+++ b/packages/panel/package.json
@@ -40,8 +40,7 @@
     "@hcengineering/chunter": "^0.6.2",
     "@hcengineering/presentation": "^0.6.2",
     "@hcengineering/activity": "^0.6.0",
-    "@hcengineering/calendar": "^0.6.3",
-    "@hcengineering/notification": "^0.6.7"
+    "@hcengineering/calendar": "^0.6.3"
   },
   "repository": "https://github.com/hcenginneing/anticrm",
   "publishConfig": {
diff --git a/packages/panel/src/components/Panel.svelte b/packages/panel/src/components/Panel.svelte
index 9531a63ac1..66768351db 100644
--- a/packages/panel/src/components/Panel.svelte
+++ b/packages/panel/src/components/Panel.svelte
@@ -17,10 +17,15 @@
   import activity from '@hcengineering/activity'
   import calendar from '@hcengineering/calendar'
   import type { Doc } from '@hcengineering/core'
-  import notification from '@hcengineering/notification'
   import type { Asset } from '@hcengineering/platform'
-  import { AnySvelteComponent, Component, Panel, Icon, Scroller } from '@hcengineering/ui'
-  import { deviceOptionsStore as deviceInfo } from '@hcengineering/ui'
+  import {
+    AnySvelteComponent,
+    Component,
+    deviceOptionsStore as deviceInfo,
+    Icon,
+    Panel,
+    Scroller
+  } from '@hcengineering/ui'
 
   export let title: string | undefined = undefined
   export let subtitle: string | undefined = undefined
@@ -89,7 +94,6 @@
 
   <svelte:fragment slot="utils">
     <Component is={calendar.component.DocReminder} props={{ value: object, title }} />
-    <Component is={notification.component.LastViewEditor} props={{ value: object }} />
     {#if isUtils && $$slots.utils}
       <div class="buttons-divider" />
       <slot name="utils" />
diff --git a/packages/presentation/src/components/AttributeBarEditor.svelte b/packages/presentation/src/components/AttributeBarEditor.svelte
index ca93c45f5c..569a43c2ee 100644
--- a/packages/presentation/src/components/AttributeBarEditor.svelte
+++ b/packages/presentation/src/components/AttributeBarEditor.svelte
@@ -15,8 +15,8 @@
 -->
 <script lang="ts">
   import type { Class, Doc, Ref } from '@hcengineering/core'
-  import { Label, tooltip } from '@hcengineering/ui'
   import type { AnySvelteComponent, ButtonKind, ButtonSize } from '@hcengineering/ui'
+  import { Label, tooltip } from '@hcengineering/ui'
   import { createEventDispatcher } from 'svelte'
   import { getAttribute, KeyedAttribute, updateAttribute } from '../attributes'
   import { getAttributeEditor, getClient } from '../utils'
@@ -38,8 +38,7 @@
   const client = getClient()
   const hierarchy = client.getHierarchy()
   const dispatch = createEventDispatcher()
-
-  let editor: Promise<void | AnySvelteComponent> | undefined
+  let editor: AnySvelteComponent | undefined
 
   function onChange (value: any) {
     const doc = object as Doc
@@ -47,63 +46,64 @@
       ;(doc as any)[attributeKey] = value
       dispatch('update', { key, value })
     } else {
-      updateAttribute(client, doc, _class, { key: attributeKey, attr: attribute }, value)
+      updateAttribute(client, doc, doc._class, { key: attributeKey, attr: attribute }, value)
     }
   }
 
+  function getEditor (_class: Ref<Class<Doc>>, key: KeyedAttribute | string) {
+    getAttributeEditor(client, _class, key).then((p) => (editor = p))
+  }
+
+  $: getEditor(_class, key)
+
   $: attribute = typeof key === 'string' ? hierarchy.getAttribute(_class, key) : key.attr
   $: attributeKey = typeof key === 'string' ? key : key.key
-  $: editor = getAttributeEditor(client, _class, key)
   $: isReadonly = (attribute.readonly ?? false) || readonly
 </script>
 
 {#if editor}
-  {#await editor then instance}
-    {#if instance}
-      {#if showHeader}
-        <span
-          class="overflow-label"
-          use:tooltip={{
-            component: Label,
-            props: { label: attribute.label }
-          }}><Label label={attribute.label} /></span
-        >
-        <div class="flex flex-grow min-w-0">
-          <svelte:component
-            this={instance}
-            readonly={isReadonly}
-            label={attribute?.label}
-            placeholder={attribute?.label}
-            {kind}
-            {size}
-            {width}
-            {justify}
-            type={attribute?.type}
-            {maxWidth}
-            {attributeKey}
-            value={getAttribute(client, object, { key: attributeKey, attr: attribute })}
-            space={object.space}
-            {onChange}
-            {focus}
-            {object}
-          />
-        </div>
-      {:else}
-        <div style="grid-column: 1/3;">
-          <svelte:component
-            this={instance}
-            type={attribute?.type}
-            {maxWidth}
-            {attributeKey}
-            value={getAttribute(client, object, { key: attributeKey, attr: attribute })}
-            readonly={isReadonly}
-            space={object.space}
-            {onChange}
-            {focus}
-            {object}
-          />
-        </div>
-      {/if}
-    {/if}
-  {/await}
+  {#if showHeader}
+    <span
+      class="overflow-label"
+      use:tooltip={{
+        component: Label,
+        props: { label: attribute.label }
+      }}><Label label={attribute.label} /></span
+    >
+    <div class="flex flex-grow min-w-0">
+      <svelte:component
+        this={editor}
+        readonly={isReadonly}
+        label={attribute?.label}
+        placeholder={attribute?.label}
+        {kind}
+        {size}
+        {width}
+        {justify}
+        type={attribute?.type}
+        {maxWidth}
+        {attributeKey}
+        value={getAttribute(client, object, { key: attributeKey, attr: attribute })}
+        space={object.space}
+        {onChange}
+        {focus}
+        {object}
+      />
+    </div>
+  {:else}
+    <div style="grid-column: 1/3;">
+      <svelte:component
+        this={editor}
+        type={attribute?.type}
+        {maxWidth}
+        {attributeKey}
+        value={getAttribute(client, object, { key: attributeKey, attr: attribute })}
+        readonly={isReadonly}
+        space={object.space}
+        {onChange}
+        {focus}
+        {object}
+      />
+    </div>
+  {/if}
 {/if}
diff --git a/packages/presentation/src/utils.ts b/packages/presentation/src/utils.ts
index e7dbec7130..8ddd47d416 100644
--- a/packages/presentation/src/utils.ts
+++ b/packages/presentation/src/utils.ts
@@ -312,6 +312,7 @@ export async function getAttributeEditor (
   _class: Ref<Class<Obj>>,
   key: KeyedAttribute | string
 ): Promise<AnySvelteComponent | undefined> {
+  console.log('get attribute editor', _class, key)
   const hierarchy = client.getHierarchy()
   const attribute = typeof key === 'string' ? hierarchy.getAttribute(_class, key) : key.attr
   const presenterClass = attribute !== undefined ? getAttributePresenterClass(hierarchy, attribute) : undefined
@@ -320,7 +321,6 @@ export async function getAttributeEditor (
     return
   }
 
-  const typeClass = hierarchy.getClass(presenterClass.attrClass)
   let mixin: Ref<Mixin<AttributeEditor>>
 
   switch (presenterClass.category) {
@@ -337,16 +337,9 @@ export async function getAttributeEditor (
     }
   }
 
-  let editorMixin = hierarchy.as(typeClass, mixin)
-  let parent = typeClass.extends
+  const editorMixin = hierarchy.classHierarchyMixin(presenterClass.attrClass, mixin)
 
-  while (editorMixin.inlineEditor === undefined && parent !== undefined) {
-    const parentClass = hierarchy.getClass(parent)
-    editorMixin = hierarchy.as(parentClass, mixin)
-    parent = parentClass.extends
-  }
-
-  if (editorMixin.inlineEditor === undefined) {
+  if (editorMixin?.inlineEditor === undefined) {
     // if (presenterClass.category === 'array') {
     //   // NOTE: Don't show error for array attributes for compatibility with previous implementation
     // } else {
diff --git a/plugins/activity-resources/src/components/Activity.svelte b/plugins/activity-resources/src/components/Activity.svelte
index 1fad244ea2..5a7126f389 100644
--- a/plugins/activity-resources/src/components/Activity.svelte
+++ b/plugins/activity-resources/src/components/Activity.svelte
@@ -13,32 +13,32 @@
 // limitations under the License.
 -->
 <script lang="ts">
-  import activity, { TxViewlet, ActivityFilter } from '@hcengineering/activity'
+  import activity, { ActivityFilter, TxViewlet } from '@hcengineering/activity'
   import chunter from '@hcengineering/chunter'
   import core, { Class, Doc, Ref, SortingOrder } from '@hcengineering/core'
+  import notification, { LastView } from '@hcengineering/notification'
   import { getResource, IntlString } from '@hcengineering/platform'
   import { createQuery, getClient } from '@hcengineering/presentation'
-  import notification from '@hcengineering/notification'
   import {
+    ActionIcon,
     Component,
+    eventToHTMLElement,
     Grid,
+    Icon,
     IconActivity,
     Label,
     Scroller,
-    Icon,
     showPopup,
-    Spinner,
-    ActionIcon,
-    eventToHTMLElement
+    Spinner
   } from '@hcengineering/ui'
-  import { ActivityKey, activityKey, DisplayTx, newActivity } from '../activity'
-  import TxView from './TxView.svelte'
-  import { filterCollectionTxes } from '../utils'
   import { Writable } from 'svelte/store'
+  import { ActivityKey, activityKey, DisplayTx, newActivity } from '../activity'
   import activityPlg from '../plugin'
+  import { filterCollectionTxes } from '../utils'
   import FilterPopup from './FilterPopup.svelte'
-  import IconFilter from './icons/Filter.svelte'
   import IconClose from './icons/Close.svelte'
+  import IconFilter from './icons/Filter.svelte'
+  import TxView from './TxView.svelte'
 
   export let object: Doc
   export let integrate: boolean = false
@@ -71,7 +71,7 @@
   getResource(notification.function.GetNotificationClient).then((res) => {
     lastViews = res().getLastViews()
   })
-  let lastViews: Writable<Map<Ref<Doc>, number>> | undefined
+  let lastViews: Writable<LastView> | undefined
 
   let viewlets: Map<ActivityKey, TxViewlet>
 
@@ -112,8 +112,8 @@
 
   $: newTxPos = newTx(filtered, $lastViews)
 
-  function newTx (txes: DisplayTx[], lastViews: Map<Ref<Doc>, number> | undefined): number {
-    const lastView = lastViews?.get(object._id)
+  function newTx (txes: DisplayTx[], lastViews: LastView | undefined): number {
+    const lastView = (lastViews as any)?.[object._id]
     if (lastView === undefined || lastView === -1) return -1
     for (let index = 0; index < txes.length; index++) {
       const tx = txes[index]
diff --git a/plugins/board-resources/src/components/ListHeader.svelte b/plugins/board-resources/src/components/ListHeader.svelte
index 8277031c72..a7500d610c 100644
--- a/plugins/board-resources/src/components/ListHeader.svelte
+++ b/plugins/board-resources/src/components/ListHeader.svelte
@@ -1,7 +1,6 @@
 <script lang="ts">
-  import notification from '@hcengineering/notification'
   import { State } from '@hcengineering/task'
-  import { Button, Component, getEventPositionElement, getPlatformColor, IconMoreV, showPopup } from '@hcengineering/ui'
+  import { Button, getEventPositionElement, getPlatformColor, IconMoreV, showPopup } from '@hcengineering/ui'
   import { ContextMenu } from '@hcengineering/view-resources'
   export let state: State
 
@@ -16,7 +15,6 @@
   <div class="flex-between h-full font-medium pr-2 pl-4">
     <span class="lines-limit-2">{state.title}</span>
     <div class="flex">
-      <Component is={notification.component.LastViewEditor} props={{ value: state }} />
       <Button icon={IconMoreV} kind="transparent" on:click={showMenu} />
     </div>
   </div>
diff --git a/plugins/board-resources/src/components/presenters/NotificationPresenter.svelte b/plugins/board-resources/src/components/presenters/NotificationPresenter.svelte
index 66f3d4be5e..01866bc38b 100644
--- a/plugins/board-resources/src/components/presenters/NotificationPresenter.svelte
+++ b/plugins/board-resources/src/components/presenters/NotificationPresenter.svelte
@@ -23,7 +23,7 @@
 
   const notificationClient = NotificationClientImpl.getClient()
   const lastViews = notificationClient.getLastViews()
-  $: lastView = $lastViews.get(object._id)
+  $: lastView = $lastViews[object._id]
   $: subscribed = lastView !== undefined && lastView !== -1
 </script>
 
diff --git a/plugins/chunter-resources/src/components/Channel.svelte b/plugins/chunter-resources/src/components/Channel.svelte
index d1ad537b43..a3c9e4aa46 100644
--- a/plugins/chunter-resources/src/components/Channel.svelte
+++ b/plugins/chunter-resources/src/components/Channel.svelte
@@ -15,7 +15,8 @@
 <script lang="ts">
   import attachment, { Attachment } from '@hcengineering/attachment'
   import type { ChunterMessage, Message } from '@hcengineering/chunter'
-  import core, { Doc, Ref, Space, Timestamp, WithLookup } from '@hcengineering/core'
+  import core, { Ref, Space, Timestamp, WithLookup } from '@hcengineering/core'
+  import { LastView } from '@hcengineering/notification'
   import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import { createQuery } from '@hcengineering/presentation'
   import { location as locationStore } from '@hcengineering/ui'
@@ -103,7 +104,7 @@
 
   function newMessagesStart (messages: Message[]): number {
     if (space === undefined) return -1
-    const lastView = $lastViews.get(space)
+    const lastView = ($lastViews as any)[space]
     if (lastView === undefined || lastView === -1) return -1
     for (let index = 0; index < messages.length; index++) {
       const message = messages[index]
@@ -113,7 +114,7 @@
   }
 
   $: markUnread($lastViews)
-  function markUnread (lastViews: Map<Ref<Doc>, number>) {
+  function markUnread (lastViews: LastView) {
     if (messages === undefined) return
     const newPos = newMessagesStart(messages)
     if (newPos !== -1 || newMessagesPos === -1) {
diff --git a/plugins/chunter-resources/src/components/ChannelView.svelte b/plugins/chunter-resources/src/components/ChannelView.svelte
index fadc89a278..2d3dc406ac 100644
--- a/plugins/chunter-resources/src/components/ChannelView.svelte
+++ b/plugins/chunter-resources/src/components/ChannelView.svelte
@@ -15,9 +15,8 @@
 <script lang="ts">
   import attachment, { Attachment } from '@hcengineering/attachment'
   import { AttachmentRefInput } from '@hcengineering/attachment-resources'
-  import { ChunterMessage, Message, ChunterSpace } from '@hcengineering/chunter'
+  import { ChunterMessage, ChunterSpace, Message } from '@hcengineering/chunter'
   import { generateId, getCurrentAccount, Ref, Space } from '@hcengineering/core'
-  import notification from '@hcengineering/notification'
   import { createQuery, getClient } from '@hcengineering/presentation'
   import { location, navigate } from '@hcengineering/ui'
   import { get } from 'svelte/store'
@@ -51,22 +50,6 @@
       },
       _id
     )
-    if (
-      chunterSpace._class === chunter.class.DirectMessage &&
-      !chunterSpace.lastMessage &&
-      chunterSpace.members.length !== 1
-    ) {
-      await Promise.all(
-        chunterSpace.members
-          .filter((accId) => accId !== me)
-          .map((accId) =>
-            client.addCollection(notification.class.LastView, space, space, chunterSpace._class, 'lastViews', {
-              user: accId,
-              lastView: 0
-            })
-          )
-      )
-    }
 
     // Create an backlink to document
     await createBacklinks(client, space, chunter.class.ChunterSpace, _id, message)
diff --git a/plugins/chunter-resources/src/components/Message.svelte b/plugins/chunter-resources/src/components/Message.svelte
index bf0c5b91ca..f8ffee81b3 100644
--- a/plugins/chunter-resources/src/components/Message.svelte
+++ b/plugins/chunter-resources/src/components/Message.svelte
@@ -17,12 +17,10 @@
   import { AttachmentList, AttachmentRefInput } from '@hcengineering/attachment-resources'
   import type { ChunterMessage, Message, Reaction } from '@hcengineering/chunter'
   import { EmployeeAccount } from '@hcengineering/contact'
-  import { employeeByIdStore, EmployeePresenter } from '@hcengineering/contact-resources'
+  import { Avatar, employeeByIdStore, EmployeePresenter } from '@hcengineering/contact-resources'
   import { getCurrentAccount, Ref, WithLookup } from '@hcengineering/core'
-  import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import { getResource } from '@hcengineering/platform'
   import { getClient, MessageViewer } from '@hcengineering/presentation'
-  import { Avatar } from '@hcengineering/contact-resources'
   import { EmojiPopup } from '@hcengineering/text-editor'
   import ui, { ActionIcon, Button, IconMoreH, Label, showPopup, tooltip } from '@hcengineering/ui'
   import { Action } from '@hcengineering/view'
@@ -32,6 +30,7 @@
   import chunter from '../plugin'
   import { getTime } from '../utils'
   // import Share from './icons/Share.svelte'
+  import notification, { Collaborators } from '@hcengineering/notification'
   import Bookmark from './icons/Bookmark.svelte'
   import Emoji from './icons/Emoji.svelte'
   import Thread from './icons/Thread.svelte'
@@ -52,13 +51,15 @@
   $: attachments = (message.$lookup?.attachments ?? []) as Attachment[]
 
   const client = getClient()
+  const hieararchy = client.getHierarchy()
   const dispatch = createEventDispatcher()
+  const me = getCurrentAccount()._id
 
   $: reactions = message.$lookup?.reactions as Reaction[] | undefined
 
-  const notificationClient = NotificationClientImpl.getClient()
-  const lastViews = notificationClient.getLastViews()
-  $: subscribed = ($lastViews.get(message._id) ?? -1) > -1
+  $: subscribed = (
+    hieararchy.as(message, notification.mixin.Collaborators) as any as Collaborators
+  ).collaborators?.includes(me)
   $: subscribeAction = subscribed
     ? ({
         label: chunter.string.TurnOffReplies,
diff --git a/plugins/chunter-resources/src/components/Thread.svelte b/plugins/chunter-resources/src/components/Thread.svelte
index 57a52668b0..9162e4d16e 100644
--- a/plugins/chunter-resources/src/components/Thread.svelte
+++ b/plugins/chunter-resources/src/components/Thread.svelte
@@ -149,7 +149,7 @@
     await client.tx(tx)
 
     // Create an backlink to document
-    await createBacklinks(client, parent.space, chunter.class.ChunterSpace, commentId, message)
+    await createBacklinks(client, parent._id, parent._class, commentId, message)
 
     commentId = generateId()
     loading = false
diff --git a/plugins/chunter-resources/src/components/ThreadView.svelte b/plugins/chunter-resources/src/components/ThreadView.svelte
index d44c7ae9b0..9dca2df1ca 100644
--- a/plugins/chunter-resources/src/components/ThreadView.svelte
+++ b/plugins/chunter-resources/src/components/ThreadView.svelte
@@ -16,7 +16,8 @@
   import attachment, { Attachment } from '@hcengineering/attachment'
   import { AttachmentRefInput } from '@hcengineering/attachment-resources'
   import type { ChunterMessage, Message, ThreadMessage } from '@hcengineering/chunter'
-  import core, { Doc, generateId, getCurrentAccount, Ref, Space } from '@hcengineering/core'
+  import core, { generateId, getCurrentAccount, Ref, Space } from '@hcengineering/core'
+  import { LastView } from '@hcengineering/notification'
   import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import { createQuery, getClient } from '@hcengineering/presentation'
   import { getCurrentLocation, IconClose, Label, navigate } from '@hcengineering/ui'
@@ -150,7 +151,7 @@
     )
 
     // Create an backlink to document
-    await createBacklinks(client, currentSpace, chunter.class.ChunterSpace, commentId, message)
+    await createBacklinks(client, _id, chunter.class.Message, commentId, message)
 
     commentId = generateId()
     isScrollForced = true
@@ -158,8 +159,8 @@
   }
   let comments: ThreadMessage[] = []
 
-  function newMessagesStart (comments: ThreadMessage[], lastViews: Map<Ref<Doc>, number>): number {
-    const lastView = lastViews.get(_id)
+  function newMessagesStart (comments: ThreadMessage[], lastViews: LastView): number {
+    const lastView = (lastViews as any)[_id]
     if (lastView === undefined || lastView === -1) return -1
     for (let index = 0; index < comments.length; index++) {
       const comment = comments[index]
@@ -169,7 +170,7 @@
   }
 
   $: markUnread($lastViews)
-  function markUnread (lastViews: Map<Ref<Doc>, number>) {
+  function markUnread (lastViews: LastView) {
     const newPos = newMessagesStart(comments, lastViews)
     if (newPos !== -1 || newMessagesPos === -1) {
       newMessagesPos = newPos
diff --git a/plugins/chunter-resources/src/index.ts b/plugins/chunter-resources/src/index.ts
index 3814180a19..9f7f8c5288 100644
--- a/plugins/chunter-resources/src/index.ts
+++ b/plugins/chunter-resources/src/index.ts
@@ -22,7 +22,7 @@ import chunter, {
   Message,
   ThreadMessage
 } from '@hcengineering/chunter'
-import core, { Data, Doc, DocumentQuery, Ref, RelatedDocument, Space } from '@hcengineering/core'
+import core, { Data, Doc, DocumentQuery, getCurrentAccount, Ref, RelatedDocument, Space } from '@hcengineering/core'
 import { NotificationClientImpl } from '@hcengineering/notification-resources'
 import { IntlString, Resources, translate } from '@hcengineering/platform'
 import preference from '@hcengineering/preference'
@@ -55,6 +55,7 @@ import { get, writable } from 'svelte/store'
 import { DisplayTx } from '../../activity/lib'
 import { updateBacklinksList } from './backlinks'
 import { getDmName, getTitle, getLink, resolveLocation } from './utils'
+import notification from '@hcengineering/notification'
 
 export { default as Header } from './components/Header.svelte'
 export { classIcon } from './utils'
@@ -72,20 +73,53 @@ async function MarkCommentUnread (object: ThreadMessage): Promise<void> {
 
 async function SubscribeMessage (object: Message): Promise<void> {
   const client = getClient()
-  const notificationClient = NotificationClientImpl.getClient()
-  if (client.getHierarchy().isDerived(object._class, chunter.class.ThreadMessage)) {
-    await notificationClient.updateLastView(object.attachedTo, object.attachedToClass, undefined, true)
+  const acc = getCurrentAccount()
+  const hierarchy = client.getHierarchy()
+  if (hierarchy.isDerived(object._class, chunter.class.ThreadMessage)) {
+    await client.updateMixin(
+      object.attachedTo,
+      object.attachedToClass,
+      object.space,
+      notification.mixin.Collaborators,
+      {
+        $push: {
+          collaborators: acc._id
+        }
+      }
+    )
   } else {
-    await notificationClient.updateLastView(object._id, object._class, undefined, true)
+    await client.updateMixin(object._id, object._class, object.space, notification.mixin.Collaborators, {
+      $push: {
+        collaborators: acc._id
+      }
+    })
   }
 }
 
-async function UnsubscribeMessage (object: Message): Promise<void> {
+async function UnsubscribeMessage (object: ChunterMessage): Promise<void> {
   const client = getClient()
+  const acc = getCurrentAccount()
+  const hierarchy = client.getHierarchy()
   const notificationClient = NotificationClientImpl.getClient()
-  if (client.getHierarchy().isDerived(object._class, chunter.class.ThreadMessage)) {
+  if (hierarchy.isDerived(object._class, chunter.class.ThreadMessage)) {
+    await client.updateMixin(
+      object.attachedTo,
+      object.attachedToClass,
+      object.space,
+      notification.mixin.Collaborators,
+      {
+        $pull: {
+          collaborators: acc._id
+        }
+      }
+    )
     await notificationClient.unsubscribe(object.attachedTo)
   } else {
+    await client.updateMixin(object._id, object._class, object.space, notification.mixin.Collaborators, {
+      $pull: {
+        collaborators: acc._id
+      }
+    })
     await notificationClient.unsubscribe(object._id)
   }
 }
diff --git a/plugins/contact-resources/package.json b/plugins/contact-resources/package.json
index 876e3c30e5..856f1dd835 100644
--- a/plugins/contact-resources/package.json
+++ b/plugins/contact-resources/package.json
@@ -38,6 +38,7 @@
     "@hcengineering/ui": "^0.6.3",
     "@hcengineering/setting": "^0.6.2",
     "@hcengineering/presentation": "^0.6.2",
+    "@hcengineering/notification": "^0.6.7",
     "@hcengineering/core": "^0.6.21",
     "@hcengineering/view": "^0.6.2",
     "@hcengineering/attachment-resources": "^0.6.0",
diff --git a/plugins/contact-resources/src/components/ChannelsDropdown.svelte b/plugins/contact-resources/src/components/ChannelsDropdown.svelte
index d7451441b9..a1fe96a496 100644
--- a/plugins/contact-resources/src/components/ChannelsDropdown.svelte
+++ b/plugins/contact-resources/src/components/ChannelsDropdown.svelte
@@ -16,7 +16,8 @@
 <script lang="ts">
   import type { Channel, ChannelProvider } from '@hcengineering/contact'
   import contact from '@hcengineering/contact'
-  import type { AttachedData, Doc, Ref, Timestamp } from '@hcengineering/core'
+  import type { AttachedData, Doc, Ref } from '@hcengineering/core'
+  import { LastView } from '@hcengineering/notification'
   import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import type { Asset, IntlString } from '@hcengineering/platform'
   import presentation from '@hcengineering/presentation'
@@ -69,7 +70,7 @@
   function getProvider (
     item: AttachedData<Channel>,
     map: Map<Ref<ChannelProvider>, ChannelProvider>,
-    lastViews: Map<Ref<Doc>, Timestamp>
+    lastViews: LastView
   ): Item | undefined {
     const provider = map.get(item.provider)
     if (provider) {
@@ -91,13 +92,13 @@
     }
   }
 
-  function isNew (item: Channel, lastViews: Map<Ref<Doc>, Timestamp>): boolean {
+  function isNew (item: Channel, lastViews: LastView): boolean {
     if (item.lastMessage === undefined) return false
-    const lastView = (item as Channel)._id !== undefined ? lastViews.get((item as Channel)._id) : undefined
+    const lastView = (item as Channel)._id !== undefined ? lastViews[(item as Channel)._id] : undefined
     return lastView ? lastView < item.lastMessage : (item.items ?? 0) > 0
   }
 
-  async function update (value: AttachedData<Channel>[] | Channel | null, lastViews: Map<Ref<Doc>, Timestamp>) {
+  async function update (value: AttachedData<Channel>[] | Channel | null, lastViews: LastView) {
     if (value == null) {
       displayItems = []
       return
diff --git a/plugins/contact-resources/src/components/ChannelsView.svelte b/plugins/contact-resources/src/components/ChannelsView.svelte
index fc4d870970..95e22e237a 100644
--- a/plugins/contact-resources/src/components/ChannelsView.svelte
+++ b/plugins/contact-resources/src/components/ChannelsView.svelte
@@ -15,14 +15,15 @@
 -->
 <script lang="ts">
   import type { Channel, ChannelProvider } from '@hcengineering/contact'
-  import type { AttachedData, Doc, Ref, Timestamp } from '@hcengineering/core'
+  import type { AttachedData, Doc, Ref } from '@hcengineering/core'
+  import { LastView } from '@hcengineering/notification'
   import type { Asset, IntlString } from '@hcengineering/platform'
   import type { AnyComponent } from '@hcengineering/ui'
+  import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import { Button } from '@hcengineering/ui'
   import { createEventDispatcher } from 'svelte'
   import { getChannelProviders } from '../utils'
   import ChannelsPopup from './ChannelsPopup.svelte'
-  import { NotificationClientImpl } from '@hcengineering/notification-resources'
 
   export let value: AttachedData<Channel>[] | Channel | null
   export let size: 'small' | 'medium' | 'large' | 'x-large' = 'large'
@@ -46,7 +47,7 @@
   function getProvider (
     item: AttachedData<Channel>,
     map: Map<Ref<ChannelProvider>, ChannelProvider>,
-    lastViews: Map<Ref<Doc>, Timestamp>
+    lastViews: LastView
   ): any | undefined {
     const provider = map.get(item.provider)
     if (provider) {
@@ -64,13 +65,13 @@
     }
   }
 
-  function isNew (item: Channel, lastViews: Map<Ref<Doc>, Timestamp>): boolean {
+  function isNew (item: Channel, lastViews: LastView): boolean {
     if (item.lastMessage === undefined) return false
-    const lastView = (item as Channel)._id !== undefined ? lastViews.get((item as Channel)._id) : undefined
+    const lastView = (item as Channel)._id !== undefined ? lastViews[(item as Channel)._id] : undefined
     return lastView ? lastView < item.lastMessage : (item.items ?? 0) > 0
   }
 
-  async function update (value: AttachedData<Channel>[] | Channel | null, lastViews: Map<Ref<Doc>, Timestamp>) {
+  async function update (value: AttachedData<Channel>[] | Channel | null, lastViews: LastView) {
     if (value === null) {
       displayItems = []
       return
diff --git a/plugins/contact-resources/src/components/UserBoxList.svelte b/plugins/contact-resources/src/components/UserBoxList.svelte
index 448bdb8d9b..df0fbc8046 100644
--- a/plugins/contact-resources/src/components/UserBoxList.svelte
+++ b/plugins/contact-resources/src/components/UserBoxList.svelte
@@ -18,12 +18,12 @@
   import type { IntlString } from '@hcengineering/platform'
   import { Button, ButtonKind, ButtonSize, Label, showPopup, TooltipAlignment } from '@hcengineering/ui'
   import { createEventDispatcher } from 'svelte'
-  import { createQuery } from '@hcengineering/presentation'
-  import Members from './icons/Members.svelte'
-  import UsersPopup from './UsersPopup.svelte'
-  import UserInfo from './UserInfo.svelte'
-  import CombineAvatars from './CombineAvatars.svelte'
   import plugin from '../plugin'
+  import { employeeByIdStore } from '../utils'
+  import CombineAvatars from './CombineAvatars.svelte'
+  import Members from './icons/Members.svelte'
+  import UserInfo from './UserInfo.svelte'
+  import UsersPopup from './UsersPopup.svelte'
 
   export let items: Ref<Employee>[] = []
   export let _class: Ref<Class<Employee>> = contact.class.Employee
@@ -40,13 +40,8 @@
   export let emptyLabel = plugin.string.Members
   export let readonly: boolean = false
 
-  let persons: Employee[] = []
-
-  const query = createQuery()
-
-  $: query.query<Employee>(_class, { _id: { $in: items } }, (result) => {
-    persons = result
-  })
+  let persons: Employee[] = items.map((p) => $employeeByIdStore.get(p)).filter((p) => p !== undefined) as Employee[]
+  $: persons = items.map((p) => $employeeByIdStore.get(p)).filter((p) => p !== undefined) as Employee[]
 
   const dispatch = createEventDispatcher()
 
diff --git a/plugins/notification-assets/lang/en.json b/plugins/notification-assets/lang/en.json
index 6ad03f1afc..77ed505029 100644
--- a/plugins/notification-assets/lang/en.json
+++ b/plugins/notification-assets/lang/en.json
@@ -15,6 +15,7 @@
     "Remove": "Delete notification",
     "RemoveAll": "Delete all notifications",
     "MarkAllAsRead": "Mark all notifications as read",
-    "MarkAsRead": "Mark as read"
+    "MarkAsRead": "Mark as read",
+    "Collaborators": "Collaborators"
   }
 }
diff --git a/plugins/notification-assets/lang/ru.json b/plugins/notification-assets/lang/ru.json
index c99d51820a..8652cdd4cb 100644
--- a/plugins/notification-assets/lang/ru.json
+++ b/plugins/notification-assets/lang/ru.json
@@ -15,6 +15,7 @@
     "Remove": "Удалить нотификацию",
     "RemoveAll": "Удалить все нотификации",
     "MarkAllAsRead": "Отметить все нотификации как прочитанные",
-    "MarkAsRead": "Отметить нотификация прочитанной"
+    "MarkAsRead": "Отметить нотификация прочитанной",
+    "Collaborators": "Участники"
   }
 }
diff --git a/plugins/notification-resources/src/components/BrowserNotificatator.svelte b/plugins/notification-resources/src/components/BrowserNotificatator.svelte
index 8fd184dd13..28dfa0422c 100644
--- a/plugins/notification-resources/src/components/BrowserNotificatator.svelte
+++ b/plugins/notification-resources/src/components/BrowserNotificatator.svelte
@@ -112,6 +112,7 @@
     }
   }
   const client = getClient()
+  const hierarchy = client.getHierarchy()
 
   let clearTimer: number | undefined
 
@@ -136,7 +137,7 @@
       alreadyShown.clear()
     }, 5000)
 
-    const lastView = $lastViews.get(lastViewId)
+    const lastView = ($lastViews as any)[lastViewId]
     if ((lastView ?? notifyInstance.modifiedOn) > 0) {
       await notificationClient.updateLastView(
         lastViewId,
@@ -154,16 +155,10 @@
     })
 
     notification.onclick = () => {
-      if (notifyInstance.action !== undefined) {
-        showPanel(
-          notifyInstance.action.component,
-          notifyInstance.action.objectId,
-          notifyInstance.action.objectClass,
-          'content'
-        )
-      } else {
-        showPanel(view.component.EditDoc, notifyInstance.attachedTo, notifyInstance.attachedToClass, 'content')
-      }
+      const targetClass = hierarchy.getClass(notifyInstance.attachedToClass)
+      const panelComponent = hierarchy.as(targetClass, view.mixin.ObjectPanel)
+      const component = panelComponent.component ?? view.component.EditDoc
+      showPanel(component, notifyInstance.attachedTo, notifyInstance.attachedToClass, 'content')
     }
   }
 </script>
diff --git a/plugins/notification-resources/src/components/LastViewEditor.svelte b/plugins/notification-resources/src/components/LastViewEditor.svelte
deleted file mode 100644
index ff4ee40547..0000000000
--- a/plugins/notification-resources/src/components/LastViewEditor.svelte
+++ /dev/null
@@ -1,39 +0,0 @@
-<!--
-// Copyright © 2022 Hardcore Engineering Inc.
-//
-// Licensed under the Eclipse Public License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License. You may
-// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-//
-// See the License for the specific language governing permissions and
-// limitations under the License.
--->
-<script lang="ts">
-  import { Doc } from '@hcengineering/core'
-  import { Button, tooltip } from '@hcengineering/ui'
-  import notification from '../plugin'
-  import { NotificationClientImpl } from '../utils'
-
-  export let value: Doc
-
-  const notificationClient = NotificationClientImpl.getClient()
-  const lastViews = notificationClient.getLastViews()
-  $: lastView = $lastViews.get(value._id)
-  $: subscribed = lastView !== undefined && lastView !== -1
-</script>
-
-<div use:tooltip={{ label: subscribed ? notification.string.DontTrack : notification.string.Track }}>
-  <Button
-    size={'medium'}
-    kind={'transparent'}
-    icon={subscribed ? notification.icon.Track : notification.icon.DontTrack}
-    on:click={() => {
-      if (subscribed) notificationClient.unsubscribe(value._id)
-      else notificationClient.updateLastView(value._id, value._class, undefined, true)
-    }}
-  />
-</div>
diff --git a/plugins/notification-resources/src/components/NotificationPresenter.svelte b/plugins/notification-resources/src/components/NotificationPresenter.svelte
index a7fa04dec0..09bebe29b3 100644
--- a/plugins/notification-resources/src/components/NotificationPresenter.svelte
+++ b/plugins/notification-resources/src/components/NotificationPresenter.svelte
@@ -23,7 +23,7 @@
   const notificationClient = NotificationClientImpl.getClient()
   const lastViews = notificationClient.getLastViews()
 
-  $: lastView = $lastViews.get(value._id)
+  $: lastView = ($lastViews as any)[value._id]
   $: hasNotification = lastView !== undefined && lastView !== -1 && lastView < value.modifiedOn
 </script>
 
diff --git a/plugins/notification-resources/src/index.ts b/plugins/notification-resources/src/index.ts
index 9dffaefd6c..5e95e00c96 100644
--- a/plugins/notification-resources/src/index.ts
+++ b/plugins/notification-resources/src/index.ts
@@ -18,7 +18,6 @@ import { Resources } from '@hcengineering/platform'
 import NotificationsPopup from './components/NotificationsPopup.svelte'
 import NotificationSettings from './components/NotificationSettings.svelte'
 import NotificationPresenter from './components/NotificationPresenter.svelte'
-import LastViewEditor from './components/LastViewEditor.svelte'
 import { NotificationClientImpl } from './utils'
 
 export * from './utils'
@@ -29,8 +28,7 @@ export default async (): Promise<Resources> => ({
   component: {
     NotificationsPopup,
     NotificationPresenter,
-    NotificationSettings,
-    LastViewEditor
+    NotificationSettings
   },
   function: {
     GetNotificationClient: NotificationClientImpl.getClient
diff --git a/plugins/notification-resources/src/utils.ts b/plugins/notification-resources/src/utils.ts
index 343fe6f540..bc326deb61 100644
--- a/plugins/notification-resources/src/utils.ts
+++ b/plugins/notification-resources/src/utils.ts
@@ -14,31 +14,33 @@
 // limitations under the License.
 //
 
-import core, { Class, Doc, getCurrentAccount, Ref, Timestamp } from '@hcengineering/core'
+import core, { Account, Class, Doc, getCurrentAccount, Ref, Timestamp } from '@hcengineering/core'
 import notification, { LastView, NotificationClient } from '@hcengineering/notification'
 import { createQuery, getClient } from '@hcengineering/presentation'
-import { writable, Writable } from 'svelte/store'
+import { get, writable, Writable } from 'svelte/store'
 
 /**
  * @public
  */
 export class NotificationClientImpl implements NotificationClient {
   protected static _instance: NotificationClientImpl | undefined = undefined
-  private lastViews = new Map<Ref<Doc>, LastView>()
-  private readonly lastViewsStore = writable(new Map<Ref<Doc>, Timestamp>())
+  private readonly lastViewsStore = writable<LastView>()
 
   private readonly lastViewQuery = createQuery()
+  private readonly user: Ref<Account>
 
   private constructor () {
-    this.lastViewQuery.query(notification.class.LastView, { user: getCurrentAccount()._id }, (result) => {
-      const res: Map<Ref<Doc>, Timestamp> = new Map<Ref<Doc>, Timestamp>()
-      const lastViews: Map<Ref<Doc>, LastView> = new Map<Ref<Doc>, LastView>()
-      result.forEach((p) => {
-        res.set(p.attachedTo, p.lastView)
-        lastViews.set(p.attachedTo, p)
-      })
-      this.lastViews = lastViews
-      this.lastViewsStore.set(res)
+    this.user = getCurrentAccount()._id
+    this.lastViewQuery.query(notification.class.LastView, { user: this.user }, (result) => {
+      this.lastViewsStore.set(result[0])
+      if (result[0] === undefined) {
+        const client = getClient()
+        const u = client.txFactory.createTxCreateDoc(notification.class.LastView, notification.space.Notifications, {
+          user: this.user
+        })
+        u.space = core.space.DerivedTx
+        void client.tx(u)
+      }
     })
   }
 
@@ -53,7 +55,7 @@ export class NotificationClientImpl implements NotificationClient {
     return NotificationClientImpl._instance
   }
 
-  getLastViews (): Writable<Map<Ref<Doc>, Timestamp>> {
+  getLastViews (): Writable<LastView> {
     return this.lastViewsStore
   }
 
@@ -64,39 +66,35 @@ export class NotificationClientImpl implements NotificationClient {
     force: boolean = false
   ): Promise<void> {
     const client = getClient()
-    const user = getCurrentAccount()._id
+    const hierarchy = client.getHierarchy()
+    const mixin = hierarchy.classHierarchyMixin(_class, notification.mixin.TrackedDoc)
+    if (mixin === undefined) return
     const lastView = time ?? new Date().getTime()
-    const current = this.lastViews.get(_id)
-    if (current !== undefined) {
-      if (current.lastView === -1 && !force) return
-      if (current.lastView < lastView || force) {
-        const u = client.txFactory.createTxUpdateDoc(current._class, current.space, current._id, {
-          lastView
-        })
-        u.space = core.space.DerivedTx
-        await client.tx(u)
+    const obj = get(this.lastViewsStore)
+    if (obj !== undefined) {
+      const current = obj[_id] as Timestamp | undefined
+      if (current !== undefined || force) {
+        if (current === -1 && !force) return
+        if (force || (current ?? 0) < lastView) {
+          const u = client.txFactory.createTxUpdateDoc(obj._class, obj.space, obj._id, {
+            [_id]: lastView
+          })
+          u.space = core.space.DerivedTx
+          await client.tx(u)
+        }
       }
-    } else if (force) {
-      const u = client.txFactory.createTxCreateDoc(notification.class.LastView, notification.space.Notifications, {
-        user,
-        lastView,
-        attachedTo: _id,
-        attachedToClass: _class,
-        collection: 'lastViews'
-      })
-      u.space = core.space.DerivedTx
-      await client.tx(u)
     }
   }
 
   async unsubscribe (_id: Ref<Doc>): Promise<void> {
     const client = getClient()
-    const user = getCurrentAccount()._id
-    const current = await client.findOne(notification.class.LastView, { attachedTo: _id, user })
-    if (current !== undefined) {
-      await client.updateDoc(current._class, current.space, current._id, {
-        lastView: -1
+    const obj = get(this.lastViewsStore)
+    if (obj !== undefined) {
+      const u = client.txFactory.createTxUpdateDoc(obj._class, obj.space, obj._id, {
+        [_id]: -1
       })
+      u.space = core.space.DerivedTx
+      await client.tx(u)
     }
   }
 }
diff --git a/plugins/notification/src/index.ts b/plugins/notification/src/index.ts
index c4715f1ab1..a2e8de3309 100644
--- a/plugins/notification/src/index.ts
+++ b/plugins/notification/src/index.ts
@@ -13,29 +13,20 @@
 // limitations under the License.
 //
 
-import type { Account, AttachedDoc, Class, Doc, Mixin, Ref, Space, Timestamp, TxCUD } from '@hcengineering/core'
+import { Account, AttachedDoc, Class, Doc, Mixin, Ref, Space, Timestamp, TxCUD } from '@hcengineering/core'
 import type { Asset, IntlString, Plugin, Resource } from '@hcengineering/platform'
 import { plugin } from '@hcengineering/platform'
+import { IntegrationType } from '@hcengineering/setting'
 import { AnyComponent } from '@hcengineering/ui'
 import { Writable } from './types'
-import { IntegrationType } from '@hcengineering/setting'
 export * from './types'
 
 /**
  * @public
  */
-export interface LastView extends AttachedDoc {
-  lastView: Timestamp
+export interface LastView extends Doc {
   user: Ref<Account>
-}
-
-/**
- * @public
- */
-export interface NotificationAction {
-  component: AnyComponent
-  objectId: Ref<Doc>
-  objectClass: Ref<Class<Doc>>
+  [key: string]: any
 }
 
 /**
@@ -46,9 +37,6 @@ export interface Notification extends AttachedDoc {
   status: NotificationStatus
   text: string
   type: Ref<NotificationType>
-
-  // Defined to open particular item if required.
-  action?: NotificationAction
 }
 
 /**
@@ -111,13 +99,27 @@ export interface SpaceLastEdit extends Class<Doc> {
 /**
  * @public
  */
-export interface LastViewAttached extends Class<AttachedDoc> {}
+export interface AnotherUserNotifications extends Class<Doc> {
+  fields: string[]
+}
 
 /**
  * @public
  */
-export interface AnotherUserNotifications extends Class<Doc> {
-  fields: string[]
+export interface ClassCollaborators extends Class<Doc> {
+  fields: string[] // Ref<Account> | Ref<Employee> | Ref<Account>[] | Ref<Employee>[]
+}
+
+/**
+ * @public
+ */
+export interface TrackedDoc extends Class<Doc> {}
+
+/**
+ * @public
+ */
+export interface Collaborators extends Doc {
+  collaborators: Ref<Account>[]
 }
 
 /**
@@ -129,7 +131,7 @@ export const notificationId = 'notification' as Plugin
  * @public
  */
 export interface NotificationClient {
-  getLastViews: () => Writable<Map<Ref<Doc>, Timestamp>>
+  getLastViews: () => Writable<LastView>
   updateLastView: (_id: Ref<Doc>, _class: Ref<Class<Doc>>, time?: Timestamp, force?: boolean) => Promise<void>
   unsubscribe: (_id: Ref<Doc>) => Promise<void>
 }
@@ -146,7 +148,9 @@ const notification = plugin(notificationId, {
   mixin: {
     SpaceLastEdit: '' as Ref<Mixin<SpaceLastEdit>>,
     AnotherUserNotifications: '' as Ref<Mixin<AnotherUserNotifications>>,
-    LastViewAttached: '' as Ref<Mixin<LastViewAttached>>
+    ClassCollaborators: '' as Ref<Mixin<ClassCollaborators>>,
+    Collaborators: '' as Ref<Mixin<Collaborators>>,
+    TrackedDoc: '' as Ref<Mixin<TrackedDoc>>
   },
   class: {
     LastView: '' as Ref<Class<LastView>>,
@@ -159,6 +163,7 @@ const notification = plugin(notificationId, {
   ids: {
     MentionNotification: '' as Ref<NotificationType>,
     DMNotification: '' as Ref<NotificationType>,
+    CollaboratorNotification: '' as Ref<NotificationType>,
     PlatformNotification: '' as Ref<NotificationProvider>,
     BrowserNotification: '' as Ref<NotificationProvider>,
     EmailNotification: '' as Ref<NotificationProvider>,
@@ -169,8 +174,7 @@ const notification = plugin(notificationId, {
   },
   component: {
     NotificationsPopup: '' as AnyComponent,
-    NotificationPresenter: '' as AnyComponent,
-    LastViewEditor: '' as AnyComponent
+    NotificationPresenter: '' as AnyComponent
   },
   icon: {
     Notifications: '' as Asset,
diff --git a/plugins/recruit-resources/src/components/EditVacancy.svelte b/plugins/recruit-resources/src/components/EditVacancy.svelte
index babfe06e49..532221faf7 100644
--- a/plugins/recruit-resources/src/components/EditVacancy.svelte
+++ b/plugins/recruit-resources/src/components/EditVacancy.svelte
@@ -15,15 +15,14 @@
 -->
 <script lang="ts">
   import { Attachments } from '@hcengineering/attachment-resources'
-  import type { Ref } from '@hcengineering/core'
-  import core from '@hcengineering/core'
+  import core, { ClassifierKind, Doc, Mixin, Ref } from '@hcengineering/core'
   import { Panel } from '@hcengineering/panel'
   import { createQuery, getClient } from '@hcengineering/presentation'
   import { Vacancy } from '@hcengineering/recruit'
   import { FullDescriptionBox } from '@hcengineering/text-editor'
   import tracker from '@hcengineering/tracker'
   import { Button, Component, EditBox, Grid, IconMoreH, showPopup } from '@hcengineering/ui'
-  import { ClassAttributeBar, ContextMenu } from '@hcengineering/view-resources'
+  import { ContextMenu, DocAttributeBar } from '@hcengineering/view-resources'
   import { createEventDispatcher } from 'svelte'
   import recruit from '../plugin'
   import VacancyApplications from './VacancyApplications.svelte'
@@ -60,6 +59,21 @@
       showPopup(ContextMenu, { object }, (ev as MouseEvent).target as HTMLElement)
     }
   }
+
+  const ignoreMixins: Set<Ref<Mixin<Doc>>> = new Set<Ref<Mixin<Doc>>>()
+  const hierarchy = client.getHierarchy()
+  let mixins: Mixin<Doc>[] = []
+
+  function getMixins (object: Doc): void {
+    if (object === undefined) return
+    const descendants = hierarchy.getDescendants(core.class.Doc).map((p) => hierarchy.getClass(p))
+
+    mixins = descendants.filter(
+      (m) => m.kind === ClassifierKind.MIXIN && !ignoreMixins.has(m._id) && hierarchy.hasMixin(object, m._id)
+    )
+  }
+
+  $: getMixins(object)
 </script>
 
 {#if object}
@@ -88,11 +102,10 @@
       {#if dir === 'column'}
         <div class="ac-subtitle">
           <div class="ac-subtitle-content">
-            <ClassAttributeBar
+            <DocAttributeBar
               {object}
-              _class={object._class}
+              {mixins}
               ignoreKeys={['name', 'description', 'fullDescription', 'private', 'archived']}
-              to={core.class.Doc}
             />
           </div>
         </div>
diff --git a/plugins/tracker-resources/src/components/issues/edit/ControlPanel.svelte b/plugins/tracker-resources/src/components/issues/edit/ControlPanel.svelte
index e2c380d0f2..3d22a51062 100644
--- a/plugins/tracker-resources/src/components/issues/edit/ControlPanel.svelte
+++ b/plugins/tracker-resources/src/components/issues/edit/ControlPanel.svelte
@@ -57,7 +57,7 @@
   $: getMixins(issue, showAllMixins)
 
   function getMixins (object: Issue, showAllMixins: boolean): void {
-    const descendants = hierarchy.getDescendants(tracker.class.Issue).map((p) => hierarchy.getClass(p))
+    const descendants = hierarchy.getDescendants(core.class.Doc).map((p) => hierarchy.getClass(p))
 
     mixins = descendants.filter(
       (m) =>
diff --git a/plugins/tracker-resources/src/components/myissues/MyIssues.svelte b/plugins/tracker-resources/src/components/myissues/MyIssues.svelte
index f89de79a6f..e44aebb737 100644
--- a/plugins/tracker-resources/src/components/myissues/MyIssues.svelte
+++ b/plugins/tracker-resources/src/components/myissues/MyIssues.svelte
@@ -14,8 +14,7 @@
 -->
 <script lang="ts">
   import type { EmployeeAccount } from '@hcengineering/contact'
-  import { DocumentQuery, getCurrentAccount, Ref } from '@hcengineering/core'
-  import notification from '@hcengineering/notification'
+  import { Doc, DocumentQuery, getCurrentAccount, Ref } from '@hcengineering/core'
   import type { IntlString } from '@hcengineering/platform'
   import { createQuery } from '@hcengineering/presentation'
   import type { Issue } from '@hcengineering/tracker'
@@ -36,10 +35,10 @@
 
   const subscribedQuery = createQuery()
   $: subscribedQuery.query(
-    notification.class.LastView,
-    { user: getCurrentAccount()._id, attachedToClass: tracker.class.Issue, lastView: { $ne: -1 } },
+    tracker.class.Issue,
+    { 'notification:mixin:Collaborators.collaborators': getCurrentAccount()._id },
     (result) => {
-      const newSub = result.map(({ attachedTo }) => attachedTo as Ref<Issue>)
+      const newSub = result.map((p) => p._id as Ref<Doc> as Ref<Issue>)
       const curSub = subscribed._id.$in
       if (curSub.length !== newSub.length || curSub.some((id, i) => newSub[i] !== id)) {
         subscribed = { _id: { $in: newSub } }
diff --git a/plugins/view-resources/src/components/EditDoc.svelte b/plugins/view-resources/src/components/EditDoc.svelte
index dece624676..cac7455e30 100644
--- a/plugins/view-resources/src/components/EditDoc.svelte
+++ b/plugins/view-resources/src/components/EditDoc.svelte
@@ -15,7 +15,7 @@
 -->
 <script lang="ts">
   import contact, { Contact, getName } from '@hcengineering/contact'
-  import { Class, ClassifierKind, Doc, Mixin, Obj, Ref } from '@hcengineering/core'
+  import core, { Class, ClassifierKind, Doc, Mixin, Obj, Ref } from '@hcengineering/core'
   import notification from '@hcengineering/notification'
   import { Panel } from '@hcengineering/panel'
   import { Asset, getResource, translate } from '@hcengineering/platform'
@@ -44,7 +44,6 @@
   let lastId: Ref<Doc> = _id
   let lastClass: Ref<Class<Doc>> = _class
   let object: Doc
-  let parentClass: Ref<Class<Doc>>
 
   const client = getClient()
   const hierarchy = client.getHierarchy()
@@ -93,9 +92,9 @@
 
   const dispatch = createEventDispatcher()
 
-  function getMixins (parentClass: Ref<Class<Doc>>, object: Doc, showAllMixins: boolean): void {
-    if (object === undefined || parentClass === undefined) return
-    const descendants = hierarchy.getDescendants(parentClass).map((p) => hierarchy.getClass(p))
+  function getMixins (object: Doc, showAllMixins: boolean): void {
+    if (object === undefined) return
+    const descendants = hierarchy.getDescendants(core.class.Doc).map((p) => hierarchy.getClass(p))
 
     mixins = descendants.filter(
       (m) =>
@@ -106,7 +105,7 @@
     )
   }
 
-  $: getMixins(parentClass, object, showAllMixins)
+  $: getMixins(object, showAllMixins)
 
   let ignoreKeys: string[] = []
   let activityOptions = { enabled: true, showInput: true }
@@ -172,7 +171,6 @@
   $: getEditorOrDefault(realObjectClass, _id)
 
   async function getEditorOrDefault (_class: Ref<Class<Doc>>, _id: Ref<Doc>): Promise<void> {
-    parentClass = hierarchy.getParentClass(_class)
     await updateKeys()
     mainEditor = getEditor(_class)
   }
@@ -232,10 +230,8 @@
   }
 
   async function getHeaderEditor (_class: Ref<Class<Doc>>): Promise<AnyComponent | undefined> {
-    const clazz = hierarchy.getClass(_class)
-    const editorMixin = hierarchy.as(clazz, view.mixin.ObjectEditorHeader)
-    if (editorMixin.editor != null) return editorMixin.editor
-    if (clazz.extends != null) return getHeaderEditor(clazz.extends)
+    const editorMixin = hierarchy.classHierarchyMixin(_class, view.mixin.ObjectEditorHeader)
+    return editorMixin?.editor
   }
 
   let headerEditor: AnyComponent | undefined = undefined
@@ -265,7 +261,7 @@
     ignoreMixins = new Set(ev.detail.ignoreMixins)
     allowedCollections = ev.detail.allowedCollections ?? []
     collectionArrays = ev.detail.collectionArrays ?? []
-    getMixins(parentClass, object, showAllMixins)
+    getMixins(object, showAllMixins)
     updateKeys()
   }
 </script>
diff --git a/plugins/view-resources/src/components/ViewletSetting.svelte b/plugins/view-resources/src/components/ViewletSetting.svelte
index fcbc29a9be..8c4441256d 100644
--- a/plugins/view-resources/src/components/ViewletSetting.svelte
+++ b/plugins/view-resources/src/components/ViewletSetting.svelte
@@ -129,20 +129,13 @@
     if (result.findIndex((p) => p.value === attribute.name) !== -1) return
     if (result.findIndex((p) => p.value === value) !== -1) return
     const { attrClass, category } = getAttributePresenterClass(hierarchy, attribute)
-    const typeClass = hierarchy.getClass(attrClass)
     const mixin =
       category === 'object'
         ? view.mixin.ObjectPresenter
         : category === 'collection'
           ? view.mixin.CollectionPresenter
           : view.mixin.AttributePresenter
-    let presenter = hierarchy.as(typeClass, mixin).presenter
-    let parent = typeClass.extends
-    while (presenter === undefined && parent !== undefined) {
-      const pclazz = hierarchy.getClass(parent)
-      presenter = hierarchy.as(pclazz, mixin).presenter
-      parent = pclazz.extends
-    }
+    const presenter = hierarchy.classHierarchyMixin(attrClass, mixin)?.presenter
     if (presenter === undefined) return
     const clazz = hierarchy.getClass(attribute.attributeOf)
 
diff --git a/plugins/view-resources/src/utils.ts b/plugins/view-resources/src/utils.ts
index 5721d41d28..02545fa23a 100644
--- a/plugins/view-resources/src/utils.ts
+++ b/plugins/view-resources/src/utils.ts
@@ -70,13 +70,8 @@ export async function getObjectPresenter (
   const hierarchy = client.getHierarchy()
   const mixin = isCollectionAttr ? view.mixin.CollectionPresenter : view.mixin.ObjectPresenter
   const clazz = hierarchy.getClass(_class)
-  let mixinClazz = hierarchy.getClass(_class)
-  let presenterMixin = hierarchy.as(clazz, mixin)
-  while (presenterMixin.presenter === undefined && mixinClazz.extends !== undefined) {
-    presenterMixin = hierarchy.as(mixinClazz, mixin)
-    mixinClazz = hierarchy.getClass(mixinClazz.extends)
-  }
-  if (presenterMixin.presenter === undefined) {
+  const presenterMixin = hierarchy.classHierarchyMixin(_class, mixin)
+  if (presenterMixin?.presenter === undefined) {
     throw new Error(
       `object presenter not found for class=${_class}, mixin=${mixin}, preserve key ${JSON.stringify(preserveKey)}`
     )
@@ -141,16 +136,8 @@ async function getAttributePresenter (
   const presenterClass = getAttributePresenterClass(hierarchy, attribute)
   const isCollectionAttr = presenterClass.category === 'collection'
   const mixin = isCollectionAttr ? view.mixin.CollectionPresenter : view.mixin.AttributePresenter
-  const clazz = hierarchy.getClass(presenterClass.attrClass)
-  let presenterMixin = hierarchy.as(clazz, mixin)
-  let parent = clazz.extends
-  while (presenterMixin.presenter === undefined && parent !== undefined) {
-    const pclazz = hierarchy.getClass(parent)
-    presenterClass.attrClass = parent
-    presenterMixin = hierarchy.as(pclazz, mixin)
-    parent = pclazz.extends
-  }
-  if (presenterMixin.presenter === undefined) {
+  const presenterMixin = hierarchy.classHierarchyMixin(presenterClass.attrClass, mixin)
+  if (presenterMixin?.presenter === undefined) {
     throw new Error('attribute presenter not found for ' + JSON.stringify(preserveKey))
   }
   const resultKey = preserveKey.sortingKey ?? preserveKey.key
@@ -657,14 +644,8 @@ export async function moveToSpace (
  */
 export function getAdditionalHeader (client: TxOperations, _class: Ref<Class<Doc>>): AnyComponent[] | undefined {
   const hierarchy = client.getHierarchy()
-  const clazz = hierarchy.getClass(_class)
-  let mixinClazz = hierarchy.getClass(_class)
-  let presenterMixin = hierarchy.as(clazz, view.mixin.ListHeaderExtra)
-  while (presenterMixin.presenters === undefined && mixinClazz.extends !== undefined) {
-    presenterMixin = hierarchy.as(mixinClazz, view.mixin.ListHeaderExtra)
-    mixinClazz = hierarchy.getClass(mixinClazz.extends)
-  }
-  return presenterMixin.presenters
+  const presenterMixin = hierarchy.classHierarchyMixin(_class, view.mixin.ListHeaderExtra)
+  return presenterMixin?.presenters
 }
 
 export async function getObjectLinkFragment (
@@ -673,12 +654,7 @@ export async function getObjectLinkFragment (
   props: Record<string, any> = {},
   component: AnyComponent = view.component.EditDoc
 ): Promise<Location> {
-  let clazz = hierarchy.getClass(object._class)
-  let provider = hierarchy.as(clazz, view.mixin.LinkProvider)
-  while (provider.encode === undefined && clazz.extends !== undefined) {
-    clazz = hierarchy.getClass(clazz.extends)
-    provider = hierarchy.as(clazz, view.mixin.LinkProvider)
-  }
+  const provider = hierarchy.classHierarchyMixin(object._class, view.mixin.LinkProvider)
   if (provider?.encode !== undefined) {
     const f = await getResource(provider.encode)
     const res = await f(object, props)
diff --git a/plugins/workbench-resources/src/components/navigator/SpacesNav.svelte b/plugins/workbench-resources/src/components/navigator/SpacesNav.svelte
index 237b12bf9e..18f8fe8e99 100644
--- a/plugins/workbench-resources/src/components/navigator/SpacesNav.svelte
+++ b/plugins/workbench-resources/src/components/navigator/SpacesNav.svelte
@@ -15,7 +15,7 @@
 <script lang="ts">
   import type { Doc, Ref, Space } from '@hcengineering/core'
   import core from '@hcengineering/core'
-  import notification from '@hcengineering/notification'
+  import notification, { LastView } from '@hcengineering/notification'
   import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import { getResource } from '@hcengineering/platform'
   import preference from '@hcengineering/preference'
@@ -107,9 +107,9 @@
   $: clazz = hierarchy.getClass(model.spaceClass)
   $: lastEditMixin = hierarchy.as(clazz, notification.mixin.SpaceLastEdit)
 
-  function isChanged (space: Space, lastViews: Map<Ref<Doc>, number>): boolean {
+  function isChanged (space: Space, lastViews: LastView): boolean {
     const field = lastEditMixin?.lastEditField
-    const lastView = lastViews.get(space._id)
+    const lastView = lastViews[space._id]
     if (lastView === undefined || lastView === -1) return false
     if (field === undefined) return false
     const value = (space as any)[field]
diff --git a/plugins/workbench-resources/src/components/navigator/StarredNav.svelte b/plugins/workbench-resources/src/components/navigator/StarredNav.svelte
index 2a16a40f43..8db5b0a58e 100644
--- a/plugins/workbench-resources/src/components/navigator/StarredNav.svelte
+++ b/plugins/workbench-resources/src/components/navigator/StarredNav.svelte
@@ -15,7 +15,7 @@
 <script lang="ts">
   import type { Doc, Ref, Space } from '@hcengineering/core'
   import core from '@hcengineering/core'
-  import notification from '@hcengineering/notification'
+  import notification, { LastView } from '@hcengineering/notification'
   import { NotificationClientImpl } from '@hcengineering/notification-resources'
   import { getResource, IntlString } from '@hcengineering/platform'
   import preference from '@hcengineering/preference'
@@ -77,11 +77,11 @@
   const lastViews = notificationClient.getLastViews()
   const hierarchy = client.getHierarchy()
 
-  function isChanged (space: Space, lastViews: Map<Ref<Doc>, number>): boolean {
+  function isChanged (space: Space, lastViews: LastView): boolean {
     const clazz = hierarchy.getClass(space._class)
     const lastEditMixin = hierarchy.as(clazz, notification.mixin.SpaceLastEdit)
     const field = lastEditMixin?.lastEditField
-    const lastView = lastViews.get(space._id)
+    const lastView = lastViews[space._id]
     if (lastView === undefined || lastView === -1) return false
     if (field === undefined) return false
     const value = (space as any)[field]
diff --git a/server-plugins/contact-resources/src/index.ts b/server-plugins/contact-resources/src/index.ts
index a913b387b1..0a942a90c7 100644
--- a/server-plugins/contact-resources/src/index.ts
+++ b/server-plugins/contact-resources/src/index.ts
@@ -166,7 +166,7 @@ async function processRefArrAttribute<T extends Doc> (
   const res: Tx[] = []
   if (attr.type._class === core.class.ArrOf) {
     const arrOf = (attr.type as ArrOf<RefTo<Doc>>).of
-    if (arrOf._class === core.class.ArrOf) {
+    if (arrOf._class === core.class.RefTo) {
       if (targetClasses.includes((arrOf as RefTo<Doc>).to)) {
         const docs = await control.findAll(clazz, { [key]: oldValue })
         for (const doc of docs) {
diff --git a/server-plugins/notification-resources/src/index.ts b/server-plugins/notification-resources/src/index.ts
index ded2bd86d0..73a19db133 100644
--- a/server-plugins/notification-resources/src/index.ts
+++ b/server-plugins/notification-resources/src/index.ts
@@ -18,44 +18,46 @@ import chunter, { Backlink } from '@hcengineering/chunter'
 import contact, { Employee, EmployeeAccount, formatName } from '@hcengineering/contact'
 import core, {
   Account,
+  AnyAttribute,
+  ArrOf,
   AttachedDoc,
   Class,
-  Data,
   Doc,
   generateId,
   Hierarchy,
-  Obj,
+  IdMap,
   Ref,
+  RefTo,
   Space,
   Timestamp,
+  toIdMap,
   Tx,
   TxCollectionCUD,
   TxCreateDoc,
   TxCUD,
-  TxFactory,
-  TxProcessor
+  TxMixin,
+  TxProcessor,
+  TxUpdateDoc
 } from '@hcengineering/core'
 import notification, {
+  ClassCollaborators,
+  Collaborators,
   EmailNotification,
-  NotificationAction,
-  Notification,
   NotificationProvider,
-  NotificationStatus,
   NotificationType
 } from '@hcengineering/notification'
 import { getResource } from '@hcengineering/platform'
 import type { TriggerControl } from '@hcengineering/server-core'
 import serverNotification, {
-  HTMLPresenter,
-  TextPresenter,
   createLastViewTx,
   getEmployeeAccount,
   getEmployeeAccountById,
   getUpdateLastViewTx,
-  getEmployee
+  HTMLPresenter,
+  TextPresenter
 } from '@hcengineering/server-notification'
-import { replaceAll } from './utils'
 import { Content } from './types'
+import { replaceAll } from './utils'
 
 /**
  * @public
@@ -63,16 +65,35 @@ import { Content } from './types'
 export async function OnBacklinkCreate (tx: Tx, control: TriggerControl): Promise<Tx[]> {
   const hierarchy = control.hierarchy
   const ptx = tx as TxCollectionCUD<Doc, Backlink>
+  let res: Tx[] = []
 
   if (!checkTx(ptx, hierarchy)) return []
 
   const receiver = await getEmployeeAccount(ptx.objectId as Ref<Employee>, control)
   if (receiver === undefined) return []
+
   const sender = await getEmployeeAccountById(ptx.modifiedBy, control)
   if (sender === undefined) return []
   const backlink = getBacklink(ptx)
   const doc = await getBacklinkDoc(backlink, control)
-  return await createNotificationTxes(
+  if (doc !== undefined) {
+    const collab = hierarchy.as(doc, notification.mixin.Collaborators)
+    if (!collab.collaborators.includes(receiver._id)) {
+      const collabTx = control.txFactory.createTxMixin(
+        doc._id,
+        doc._class,
+        doc.space,
+        notification.mixin.Collaborators,
+        {
+          $push: {
+            collaborators: receiver._id
+          }
+        }
+      )
+      res.push(collabTx)
+    }
+  }
+  const notifyTx = await createNotificationTxes(
     control,
     ptx,
     notification.ids.MentionNotification,
@@ -81,6 +102,8 @@ export async function OnBacklinkCreate (tx: Tx, control: TriggerControl): Promis
     receiver,
     backlink.message
   )
+  res = [...res, ...notifyTx]
+  return res
 }
 
 function checkTx (ptx: TxCollectionCUD<Doc, Backlink>, hierarchy: Hierarchy): boolean {
@@ -142,23 +165,11 @@ async function getHtmlPart (doc: Doc, control: TriggerControl): Promise<string |
 }
 
 function getHTMLPresenter (_class: Ref<Class<Doc>>, hierarchy: Hierarchy): HTMLPresenter | undefined {
-  let clazz: Ref<Class<Obj>> | undefined = _class
-  while (clazz !== undefined) {
-    const _class = hierarchy.getClass(clazz)
-    const presenter = hierarchy.as(_class, serverNotification.mixin.HTMLPresenter)
-    if (presenter.presenter != null) return presenter
-    clazz = _class.extends
-  }
+  return hierarchy.classHierarchyMixin(_class, serverNotification.mixin.HTMLPresenter)
 }
 
 function getTextPresenter (_class: Ref<Class<Doc>>, hierarchy: Hierarchy): TextPresenter | undefined {
-  let clazz: Ref<Class<Obj>> | undefined = _class
-  while (clazz !== undefined) {
-    const _class = hierarchy.getClass(clazz)
-    const presenter = hierarchy.as(_class, serverNotification.mixin.TextPresenter)
-    if (presenter.presenter != null) return presenter
-    clazz = _class.extends
-  }
+  return hierarchy.classHierarchyMixin(_class, serverNotification.mixin.TextPresenter)
 }
 
 function fillTemplate (template: string, sender: string, doc: string, data: string): string {
@@ -204,8 +215,7 @@ export async function createNotificationTxes (
   doc: Doc | undefined,
   sender: EmployeeAccount,
   receiver: EmployeeAccount,
-  data: string = '',
-  action?: NotificationAction
+  data: string = ''
 ): Promise<Tx[]> {
   const res: Tx[] = []
 
@@ -213,22 +223,6 @@ export async function createNotificationTxes (
 
   const content = await getContent(doc, senderName, type, control, data)
 
-  if (await isAllowed(control, receiver, notification.ids.PlatformNotification)) {
-    const target = await getEmployee(receiver.employee, control)
-    if (target !== undefined) {
-      const createNotificationTx = await getPlatformNotificationTx(
-        ptx,
-        type,
-        control.txFactory,
-        target,
-        content?.text,
-        action
-      )
-
-      res.push(createNotificationTx)
-    }
-  }
-
   if (content !== undefined && (await isAllowed(control, receiver, notification.ids.EmailNotification))) {
     const emailTx = await getEmailNotificationTx(ptx, senderName, content.text, content.html, content.subject, receiver)
     if (emailTx !== undefined) {
@@ -239,41 +233,6 @@ export async function createNotificationTxes (
   return res
 }
 
-async function getPlatformNotificationTx (
-  ptx: TxCollectionCUD<Doc, AttachedDoc>,
-  type: Ref<NotificationType>,
-  txFactory: TxFactory,
-  target: Employee,
-  text?: string,
-  action?: NotificationAction
-): Promise<TxCollectionCUD<Doc, Notification>> {
-  const createTx: TxCreateDoc<Notification> = {
-    objectClass: notification.class.Notification,
-    objectSpace: notification.space.Notifications,
-    objectId: generateId(),
-    modifiedOn: ptx.modifiedOn,
-    modifiedBy: ptx.modifiedBy,
-    space: ptx.space,
-    _id: generateId(),
-    _class: core.class.TxCreateDoc,
-    attributes: {
-      tx: ptx._id,
-      status: NotificationStatus.New,
-      type
-    } as unknown as Data<Notification>
-  }
-
-  if (text !== undefined) {
-    createTx.attributes.text = text
-  }
-
-  if (action !== undefined) {
-    createTx.attributes.action = action
-  }
-
-  return txFactory.createTxCollectionCUD(target._class, target._id, target.space, 'notifications', createTx)
-}
-
 async function getEmailNotificationTx (
   ptx: TxCollectionCUD<Doc, AttachedDoc>,
   sender: string,
@@ -312,7 +271,7 @@ async function getUpdateLastViewTxes (
 ): Promise<Tx[]> {
   const updatedUsers: Set<Ref<Account>> = new Set<Ref<Account>>()
   const result: Tx[] = []
-  const tx = await getUpdateLastViewTx(control.findAll, _id, _class, modifiedOn, user)
+  const tx = await getUpdateLastViewTx(control.findAll, _id, modifiedOn, user)
   if (tx !== undefined) {
     updatedUsers.add(user)
     result.push(tx)
@@ -323,10 +282,10 @@ async function getUpdateLastViewTxes (
     const value = (doc as any)[field]
     if (value != null) {
       for (const employeeId of Array.isArray(value) ? value : [value]) {
-        const account = (await control.modelDb.findAll(core.class.Account, { employee: employeeId }, { limit: 1 }))[0]
+        const account = await getEmployeeAccount(employeeId, control)
         if (account !== undefined) {
           if (updatedUsers.has(account._id)) continue
-          const assigneeTx = await createLastViewTx(control.findAll, _id, _class, account._id)
+          const assigneeTx = await createLastViewTx(control.findAll, _id, account._id)
           if (assigneeTx !== undefined) {
             updatedUsers.add(account._id)
             result.push(assigneeTx)
@@ -343,7 +302,11 @@ async function getUpdateLastViewTxes (
  */
 export async function UpdateLastView (tx: Tx, control: TriggerControl): Promise<Tx[]> {
   const actualTx = TxProcessor.extractTx(tx)
-  if (![core.class.TxUpdateDoc, core.class.TxCreateDoc, core.class.TxMixin].includes(actualTx._class)) {
+  if (
+    ![core.class.TxUpdateDoc, core.class.TxCreateDoc, core.class.TxMixin, core.class.TxRemoveDoc].includes(
+      actualTx._class
+    )
+  ) {
     return []
   }
 
@@ -356,21 +319,22 @@ export async function UpdateLastView (tx: Tx, control: TriggerControl): Promise<
   switch (actualTx._class) {
     case core.class.TxCreateDoc: {
       const createTx = actualTx as TxCreateDoc<Doc>
-      if (control.hierarchy.isDerived(createTx.objectClass, notification.class.LastView)) {
-        return []
-      }
       if (control.hierarchy.isDerived(createTx.objectClass, core.class.AttachedDoc)) {
         const doc = TxProcessor.createDoc2Doc(createTx as TxCreateDoc<AttachedDoc>)
-        const attachedTxes = await getUpdateLastViewTxes(
-          doc,
-          doc.attachedTo,
-          doc.attachedToClass,
-          createTx.modifiedOn,
-          createTx.modifiedBy,
-          control
-        )
-        const docClass = control.hierarchy.getClass(doc._class)
-        if (!control.hierarchy.hasMixin(docClass, notification.mixin.LastViewAttached)) return attachedTxes
+        if (control.hierarchy.classHierarchyMixin(doc.attachedToClass, notification.mixin.TrackedDoc) !== undefined) {
+          const attachedTxes = await getUpdateLastViewTxes(
+            doc,
+            doc.attachedTo,
+            doc.attachedToClass,
+            createTx.modifiedOn,
+            createTx.modifiedBy,
+            control
+          )
+          result.push(...attachedTxes)
+        }
+      }
+      if (control.hierarchy.classHierarchyMixin(createTx.objectClass, notification.mixin.TrackedDoc) !== undefined) {
+        const doc = TxProcessor.createDoc2Doc(createTx)
         const parentTxes = await getUpdateLastViewTxes(
           doc,
           doc._id,
@@ -379,21 +343,34 @@ export async function UpdateLastView (tx: Tx, control: TriggerControl): Promise<
           createTx.modifiedBy,
           control
         )
-        return [...attachedTxes, ...parentTxes]
-      } else {
-        const doc = TxProcessor.createDoc2Doc(createTx)
-        return await getUpdateLastViewTxes(doc, doc._id, doc._class, createTx.modifiedOn, createTx.modifiedBy, control)
+        result.push(...parentTxes)
       }
+      return result
     }
     case core.class.TxUpdateDoc:
     case core.class.TxMixin: {
       const tx = actualTx as TxCUD<Doc>
-      const doc = (await control.findAll(tx.objectClass, { _id: tx.objectId }, { limit: 1 }))[0]
-      if (doc !== undefined) {
-        return await getUpdateLastViewTxes(doc, doc._id, doc._class, tx.modifiedOn, tx.modifiedBy, control)
+      if (control.hierarchy.classHierarchyMixin(tx.objectClass, notification.mixin.TrackedDoc) !== undefined) {
+        const doc = (await control.findAll(tx.objectClass, { _id: tx.objectId }, { limit: 1 }))[0]
+        if (doc !== undefined) {
+          return await getUpdateLastViewTxes(doc, doc._id, doc._class, tx.modifiedOn, tx.modifiedBy, control)
+        }
       }
       break
     }
+    case core.class.TxRemoveDoc: {
+      const tx = actualTx as TxCUD<Doc>
+      const lastViews = await control.findAll(notification.class.LastView, { [tx.objectId]: { $exists: true } })
+      for (const lastView of lastViews) {
+        const clearTx = control.txFactory.createTxUpdateDoc(lastView._class, lastView.space, lastView._id, {
+          $unset: {
+            [tx.objectId]: ''
+          }
+        })
+        result.push(clearTx)
+      }
+      return result
+    }
     default:
       break
   }
@@ -417,12 +394,241 @@ async function getBacklinkDoc (backlink: Backlink, control: TriggerControl): Pro
   )[0]
 }
 
+async function getValueCollaborators (
+  value: any,
+  attr: AnyAttribute,
+  control: TriggerControl
+): Promise<EmployeeAccount[]> {
+  const hierarchy = control.hierarchy
+  if (attr.type._class === core.class.RefTo) {
+    const to = (attr.type as RefTo<Doc>).to
+    if (hierarchy.isDerived(to, contact.class.Employee)) {
+      const acc = await getEmployeeAccount(value, control)
+      return acc !== undefined ? [acc] : []
+    } else if (hierarchy.isDerived(to, core.class.Account)) {
+      const acc = await getEmployeeAccountById(value, control)
+      return acc !== undefined ? [acc] : []
+    }
+  } else if (attr.type._class === core.class.ArrOf) {
+    const arrOf = (attr.type as ArrOf<RefTo<Doc>>).of
+    if (arrOf._class === core.class.RefTo) {
+      const to = (arrOf as RefTo<Doc>).to
+      if (hierarchy.isDerived(to, contact.class.Employee)) {
+        const employeeAccounts = await control.modelDb.findAll(contact.class.EmployeeAccount, {
+          employee: { $in: Array.isArray(value) ? value : [value] }
+        })
+        return employeeAccounts
+      } else if (hierarchy.isDerived(to, core.class.Account)) {
+        const employeeAccounts = await control.modelDb.findAll(contact.class.EmployeeAccount, {
+          _id: { $in: Array.isArray(value) ? value : [value] }
+        })
+        return employeeAccounts
+      }
+    }
+  }
+  return []
+}
+
+async function getKeyCollaborators (
+  doc: Doc,
+  value: any,
+  field: string,
+  control: TriggerControl
+): Promise<EmployeeAccount[] | undefined> {
+  if (value !== undefined && value !== null) {
+    const attr = control.hierarchy.findAttribute(doc._class, field)
+    if (attr !== undefined) {
+      return await getValueCollaborators(value, attr, control)
+    }
+  }
+}
+
+async function getDocCollaborators (
+  doc: Doc,
+  mixin: ClassCollaborators,
+  control: TriggerControl
+): Promise<EmployeeAccount[]> {
+  const collaborators: IdMap<EmployeeAccount> = new Map()
+  for (const field of mixin.fields) {
+    const value = (doc as any)[field]
+    const newCollaborators = await getKeyCollaborators(doc, value, field, control)
+    if (newCollaborators !== undefined) {
+      for (const newCollaborator of newCollaborators) {
+        collaborators.set(newCollaborator._id, newCollaborator)
+      }
+    }
+  }
+  return Array.from(collaborators.values())
+}
+
+function getMixinTx (
+  actualTx: TxCUD<Doc>,
+  control: TriggerControl,
+  collaborators: EmployeeAccount[]
+): TxMixin<Doc, Collaborators> {
+  return control.txFactory.createTxMixin(
+    actualTx.objectId,
+    actualTx.objectClass,
+    actualTx.objectSpace,
+    notification.mixin.Collaborators,
+    {
+      collaborators: collaborators.map((p) => p._id)
+    }
+  )
+}
+
+/**
+ * @public
+ */
+export async function CreateCollaboratorDoc (tx: Tx, control: TriggerControl): Promise<Tx[]> {
+  const res: Tx[] = []
+  const hierarchy = control.hierarchy
+  const actualTx = TxProcessor.extractTx(tx) as TxCreateDoc<Doc>
+
+  if (actualTx._class !== core.class.TxCreateDoc) return []
+  const mixin = hierarchy.classHierarchyMixin(actualTx.objectClass, notification.mixin.ClassCollaborators)
+  if (mixin !== undefined) {
+    const doc = TxProcessor.createDoc2Doc(actualTx)
+    const collaborators = await getDocCollaborators(doc, mixin, control)
+
+    const mixinTx = getMixinTx(actualTx, control, collaborators)
+    res.push(mixinTx)
+  }
+  return res
+}
+
+async function getNewCollaborators (
+  actualTx: TxUpdateDoc<Doc>,
+  mixin: ClassCollaborators,
+  doc: Doc,
+  control: TriggerControl
+): Promise<EmployeeAccount[]> {
+  const newCollaborators: IdMap<EmployeeAccount> = new Map()
+  if (actualTx.operations.$push !== undefined) {
+    for (const key in actualTx.operations.$push) {
+      if (mixin.fields.includes(key)) {
+        const value = (actualTx.operations.$push as any)[key]
+        const newCollabs = await getKeyCollaborators(doc, value, key, control)
+        if (newCollabs !== undefined) {
+          for (const newCollab of newCollabs) {
+            newCollaborators.set(newCollab._id, newCollab)
+          }
+        }
+      }
+    }
+  }
+  for (const key in actualTx.operations) {
+    if (key.startsWith('$')) continue
+    if (mixin.fields.includes(key)) {
+      const value = (actualTx.operations as any)[key]
+      const newCollabs = await getKeyCollaborators(doc, value, key, control)
+      if (newCollabs !== undefined) {
+        for (const newCollab of newCollabs) {
+          newCollaborators.set(newCollab._id, newCollab)
+        }
+      }
+    }
+  }
+  return Array.from(newCollaborators.values())
+}
+
+/**
+ * @public
+ */
+export async function UpdateCollaboratorDoc (tx: Tx, control: TriggerControl): Promise<Tx[]> {
+  const hierarchy = control.hierarchy
+  const actualTx = TxProcessor.extractTx(tx) as TxUpdateDoc<Doc>
+
+  if (actualTx._class !== core.class.TxUpdateDoc) return []
+  const clazz = hierarchy.getClass(actualTx.objectClass)
+  if (!hierarchy.hasMixin(clazz, notification.mixin.ClassCollaborators)) return []
+  const mixin = hierarchy.as(clazz, notification.mixin.ClassCollaborators)
+  const doc = (await control.findAll(actualTx.objectClass, { _id: actualTx.objectId }, { limit: 1 }))[0]
+  if (doc === undefined) return []
+  let collaborators: EmployeeAccount[] = []
+  let mixinTx: TxMixin<Doc, Collaborators> | undefined
+  if (hierarchy.hasMixin(doc, notification.mixin.Collaborators)) {
+    // we should handle change field and subscribe new collaborators
+    const collabMixin = hierarchy.as(doc, notification.mixin.Collaborators)
+    const oldCollaborators = await control.modelDb.findAll(contact.class.EmployeeAccount, {
+      _id: { $in: collabMixin.collaborators as Ref<EmployeeAccount>[] }
+    })
+    const collabs = toIdMap(oldCollaborators)
+    const newCollaborators = (await getNewCollaborators(actualTx, mixin, doc, control)).filter(
+      (p) => !collabs.has(p._id)
+    )
+
+    if (newCollaborators.length > 0) {
+      mixinTx = control.txFactory.createTxMixin(
+        actualTx.objectId,
+        actualTx.objectClass,
+        actualTx.objectSpace,
+        notification.mixin.Collaborators,
+        {
+          $push: {
+            collaborators: {
+              $each: newCollaborators.map((p) => p._id),
+              $position: 0
+            }
+          }
+        }
+      )
+    }
+  } else {
+    collaborators = await getDocCollaborators(doc, mixin, control)
+    mixinTx = getMixinTx(actualTx, control, collaborators)
+  }
+
+  return mixinTx !== undefined ? [mixinTx] : []
+}
+
+/**
+ * @public
+ */
+export async function OnAddCollborator (tx: Tx, control: TriggerControl): Promise<Tx[]> {
+  const result: Tx[] = []
+  const actualTx = TxProcessor.extractTx(tx) as TxMixin<Doc, Collaborators>
+
+  if (actualTx._class !== core.class.TxMixin) return []
+  if (actualTx.mixin !== notification.mixin.Collaborators) return []
+  if (actualTx.attributes.collaborators !== undefined) {
+    for (const collab of actualTx.attributes.collaborators) {
+      const resTx = await createLastViewTx(control.findAll, actualTx.objectId, collab)
+      if (resTx !== undefined) {
+        result.push(resTx)
+      }
+    }
+  }
+  if (actualTx.attributes.$push?.collaborators !== undefined) {
+    const collab = actualTx.attributes.$push?.collaborators
+    if (typeof collab === 'object') {
+      if ('$each' in collab) {
+        for (const collaborator of collab.$each) {
+          const resTx = await createLastViewTx(control.findAll, actualTx.objectId, collaborator)
+          if (resTx !== undefined) {
+            result.push(resTx)
+          }
+        }
+      }
+    } else {
+      const resTx = await createLastViewTx(control.findAll, actualTx.objectId, collab)
+      if (resTx !== undefined) {
+        result.push(resTx)
+      }
+    }
+  }
+  return result
+}
+
 export * from './types'
 
 // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export default async () => ({
   trigger: {
     OnBacklinkCreate,
-    UpdateLastView
+    UpdateLastView,
+    CreateCollaboratorDoc,
+    UpdateCollaboratorDoc,
+    OnAddCollborator
   }
 })
diff --git a/server-plugins/notification/src/index.ts b/server-plugins/notification/src/index.ts
index 08efd61efd..c21b1648d9 100644
--- a/server-plugins/notification/src/index.ts
+++ b/server-plugins/notification/src/index.ts
@@ -31,7 +31,6 @@ export const serverNotificationId = 'server-notification' as Plugin
 export async function getUpdateLastViewTx (
   findAll: TriggerControl['findAll'],
   attachedTo: Ref<Doc>,
-  attachedToClass: Ref<Class<Doc>>,
   lastView: number,
   user: Ref<Account>
 ): Promise<TxUpdateDoc<LastView> | TxCreateDoc<LastView> | undefined> {
@@ -39,8 +38,6 @@ export async function getUpdateLastViewTx (
     await findAll(
       notification.class.LastView,
       {
-        attachedTo,
-        attachedToClass,
         user
       },
       { limit: 1 }
@@ -48,21 +45,18 @@ export async function getUpdateLastViewTx (
   )[0]
   const factory = new TxFactory(user)
   if (current !== undefined) {
-    if (current.lastView === -1) {
+    if (current[attachedTo] === -1 || current[attachedTo] >= lastView) {
       return
     }
     const u = factory.createTxUpdateDoc(current._class, current.space, current._id, {
-      lastView
+      [attachedTo]: lastView
     })
     u.space = core.space.DerivedTx
     return u
   } else {
     const u = factory.createTxCreateDoc(notification.class.LastView, notification.space.Notifications, {
       user,
-      lastView,
-      attachedTo,
-      attachedToClass,
-      collection: 'lastViews'
+      [attachedTo]: lastView
     })
     u.space = core.space.DerivedTx
     return u
@@ -129,28 +123,28 @@ export async function getEmployee (employee: Ref<Employee>, control: TriggerCont
 export async function createLastViewTx (
   findAll: TriggerControl['findAll'],
   attachedTo: Ref<Doc>,
-  attachedToClass: Ref<Class<Doc>>,
   user: Ref<Account>
-): Promise<TxCreateDoc<LastView> | undefined> {
+): Promise<TxCreateDoc<LastView> | TxUpdateDoc<LastView> | undefined> {
   const current = (
     await findAll(
       notification.class.LastView,
       {
-        attachedTo,
-        attachedToClass,
         user
       },
       { limit: 1 }
     )
   )[0]
+  const factory = new TxFactory(user)
   if (current === undefined) {
-    const factory = new TxFactory(user)
     const u = factory.createTxCreateDoc(notification.class.LastView, notification.space.Notifications, {
       user,
-      lastView: 1,
-      attachedTo,
-      attachedToClass,
-      collection: 'lastViews'
+      [attachedTo]: 1
+    })
+    u.space = core.space.DerivedTx
+    return u
+  } else if (current[attachedTo] === undefined) {
+    const u = factory.createTxUpdateDoc(current._class, current.space, current._id, {
+      [attachedTo]: 1
     })
     u.space = core.space.DerivedTx
     return u
@@ -186,6 +180,9 @@ export default plugin(serverNotificationId, {
   },
   trigger: {
     OnBacklinkCreate: '' as Resource<TriggerFunc>,
-    UpdateLastView: '' as Resource<TriggerFunc>
+    UpdateLastView: '' as Resource<TriggerFunc>,
+    CreateCollaboratorDoc: '' as Resource<TriggerFunc>,
+    UpdateCollaboratorDoc: '' as Resource<TriggerFunc>,
+    OnAddCollborator: '' as Resource<TriggerFunc>
   }
 })
diff --git a/server-plugins/task-resources/src/index.ts b/server-plugins/task-resources/src/index.ts
index 9889564151..b2aee2cb6b 100644
--- a/server-plugins/task-resources/src/index.ts
+++ b/server-plugins/task-resources/src/index.ts
@@ -14,22 +14,12 @@
 //
 
 import { Employee } from '@hcengineering/contact'
-import core, {
-  AttachedDoc,
-  concatLink,
-  Doc,
-  Ref,
-  Tx,
-  TxCollectionCUD,
-  TxProcessor,
-  TxUpdateDoc
-} from '@hcengineering/core'
-import { NotificationAction } from '@hcengineering/notification'
-import { getMetadata, Resource } from '@hcengineering/platform'
+import { AttachedDoc, concatLink, Doc, Ref, Tx, TxCollectionCUD } from '@hcengineering/core'
+import { getMetadata } from '@hcengineering/platform'
 import serverCore, { TriggerControl } from '@hcengineering/server-core'
-import { getEmployeeAccount, getEmployeeAccountById, getUpdateLastViewTx } from '@hcengineering/server-notification'
+import { getEmployeeAccount, getEmployeeAccountById } from '@hcengineering/server-notification'
 import { createNotificationTxes } from '@hcengineering/server-notification-resources'
-import task, { Issue, Task, taskId } from '@hcengineering/task'
+import task, { Issue, taskId } from '@hcengineering/task'
 import view from '@hcengineering/view'
 import { workbenchId } from '@hcengineering/workbench'
 
@@ -60,8 +50,7 @@ export async function addAssigneeNotification (
   res: Tx[],
   issue: Doc,
   assignee: Ref<Employee>,
-  ptx: TxCollectionCUD<AttachedDoc, AttachedDoc>,
-  component?: Resource<string>
+  ptx: TxCollectionCUD<AttachedDoc, AttachedDoc>
 ): Promise<void> {
   const sender = await getEmployeeAccountById(ptx.modifiedBy, control)
   if (sender === undefined) {
@@ -73,74 +62,11 @@ export async function addAssigneeNotification (
     return
   }
 
-  // eslint-disable-next-line
-  const action: NotificationAction = {
-    component: component ?? view.component.EditDoc,
-    objectId: issue._id,
-    objectClass: issue._class
-  } as NotificationAction
-
-  const result = await createNotificationTxes(
-    control,
-    ptx,
-    task.ids.AssigneedNotification,
-    issue,
-    sender,
-    receiver,
-    undefined,
-    action
-  )
+  const result = await createNotificationTxes(control, ptx, task.ids.AssigneedNotification, issue, sender, receiver)
 
   res.push(...result)
 }
 
-/**
- * @public
- */
-export async function OnTaskUpdate (tx: Tx, control: TriggerControl): Promise<Tx[]> {
-  const actualTx = TxProcessor.extractTx(tx)
-  if (actualTx._class !== core.class.TxUpdateDoc) {
-    return []
-  }
-
-  const updateTx = actualTx as TxUpdateDoc<Task>
-
-  if (!control.hierarchy.isDerived(updateTx.objectClass, task.class.Task)) {
-    return []
-  }
-  const txes: Tx[] = []
-
-  const mainTx = await getUpdateLastViewTx(
-    control.findAll,
-    updateTx.objectId,
-    updateTx.objectClass,
-    updateTx.modifiedOn,
-    updateTx.modifiedBy
-  )
-  if (mainTx !== undefined) {
-    txes.push(mainTx)
-  }
-  if (updateTx.operations.assignee != null) {
-    const assignee = (
-      await control.modelDb.findAll(core.class.Account, { employee: updateTx.operations.assignee }, { limit: 1 })
-    )[0]
-    if (assignee !== undefined) {
-      const assigneeTx = await getUpdateLastViewTx(
-        control.findAll,
-        updateTx.objectId,
-        updateTx.objectClass,
-        updateTx.modifiedOn,
-        assignee._id
-      )
-      if (assigneeTx !== undefined) {
-        txes.push(assigneeTx)
-      }
-    }
-  }
-
-  return txes
-}
-
 // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export default async () => ({
   function: {
diff --git a/server-plugins/tracker-resources/src/index.ts b/server-plugins/tracker-resources/src/index.ts
index cd95516087..7535227593 100644
--- a/server-plugins/tracker-resources/src/index.ts
+++ b/server-plugins/tracker-resources/src/index.ts
@@ -31,7 +31,6 @@ import core, {
   WithLookup
 } from '@hcengineering/core'
 import { getMetadata } from '@hcengineering/platform'
-import { Resource } from '@hcengineering/platform/lib/platform'
 import serverCore, { TriggerControl } from '@hcengineering/server-core'
 import { addAssigneeNotification } from '@hcengineering/server-task-resources'
 import tracker, { Component, Issue, IssueParentInfo, Project, TimeSpendReport, trackerId } from '@hcengineering/tracker'
@@ -82,14 +81,7 @@ export async function addTrackerAssigneeNotification (
   assignee: Ref<Employee>,
   ptx: TxCollectionCUD<Issue, AttachedDoc>
 ): Promise<void> {
-  await addAssigneeNotification(
-    control,
-    res,
-    issue,
-    assignee,
-    ptx,
-    tracker.component.EditIssue as unknown as Resource<string>
-  )
+  await addAssigneeNotification(control, res, issue, assignee, ptx)
 }
 
 /**
@@ -169,7 +161,7 @@ export async function OnIssueUpdate (tx: Tx, control: TriggerControl): Promise<T
     if (control.hierarchy.isDerived(createTx.objectClass, tracker.class.Issue)) {
       const issue = TxProcessor.createDoc2Doc(createTx)
       const res: Tx[] = []
-      await updateIssueParentEstimations(issue, res, control, [], issue.parents)
+      updateIssueParentEstimations(issue, res, control, [], issue.parents)
 
       if (issue.assignee != null) {
         await addTrackerAssigneeNotification(
diff --git a/tests/sanity/tests/tracker.spec.ts b/tests/sanity/tests/tracker.spec.ts
index aff9fd0627..08e4bc0179 100644
--- a/tests/sanity/tests/tracker.spec.ts
+++ b/tests/sanity/tests/tracker.spec.ts
@@ -115,9 +115,11 @@ test('my-issues', async ({ page }) => {
   await expect(page.locator('.antiPanel-component')).toContainText(name)
   await openIssue(page, name)
   // click "Don't track"
-  await page.click('.buttons-group > div > .button')
+  await page.click('button:has-text("Appleseed John") >> nth=1')
+  await page.click('.selectPopup >> button:has-text("Appleseed John")')
   await page.waitForTimeout(100)
   await page.keyboard.press('Escape')
+  await page.keyboard.press('Escape')
   await expect(page.locator('.antiPanel-component')).not.toContainText(name)
 })