fix(channels): sync preserve locally cleared dialogs

deploy/migrations/0001_init.up.sql

@@ -2948,7 +2948,7 @@ CREATE TABLE public.user_update_events (
     story_payload jsonb DEFAULT '{}'::jsonb NOT NULL,
     reaction_payload jsonb DEFAULT '{}'::jsonb NOT NULL,
     CONSTRAINT user_update_events_peer_type_check CHECK (((peer_type IS NULL) OR ((peer_type)::text = ANY (ARRAY[('user'::character varying)::text, ('channel'::character varying)::text])))),
-    CONSTRAINT user_update_events_type_check CHECK (((event_type)::text = ANY (ARRAY[('new_message'::character varying)::text, ('read_history_inbox'::character varying)::text, ('read_history_outbox'::character varying)::text, ('read_message_contents'::character varying)::text, ('edit_message'::character varying)::text, ('message_poll'::character varying)::text, ('draft_message'::character varying)::text, ('quick_replies'::character varying)::text, ('new_quick_reply'::character varying)::text, ('delete_quick_reply'::character varying)::text, ('quick_reply_message'::character varying)::text, ('delete_quick_reply_messages'::character varying)::text, ('contacts_reset'::character varying)::text, ('dialog_pinned'::character varying)::text, ('pinned_dialogs'::character varying)::text, ('pinned_messages'::character varying)::text, ('dialog_unread_mark'::character varying)::text, ('peer_settings'::character varying)::text, ('peer_story_blocked'::character varying)::text, ('delete_messages'::character varying)::text, ('dialog_filter'::character varying)::text, ('dialog_filter_order'::character varying)::text, ('dialog_filters'::character varying)::text, ('folder_peers'::character varying)::text, ('channel_available_messages'::character varying)::text, ('channel_view_forum_as_messages'::character varying)::text, ('channel_state'::character varying)::text, ('saved_dialog_pinned'::character varying)::text, ('pinned_saved_dialogs'::character varying)::text, ('story'::character varying)::text, ('read_stories'::character varying)::text, ('sent_story_reaction'::character varying)::text, ('new_story_reaction'::character varying)::text, ('noop'::character varying)::text])))
+    CONSTRAINT user_update_events_type_check CHECK (((event_type)::text = ANY (ARRAY[('new_message'::character varying)::text, ('read_history_inbox'::character varying)::text, ('read_history_outbox'::character varying)::text, ('read_message_contents'::character varying)::text, ('edit_message'::character varying)::text, ('message_poll'::character varying)::text, ('draft_message'::character varying)::text, ('quick_replies'::character varying)::text, ('new_quick_reply'::character varying)::text, ('delete_quick_reply'::character varying)::text, ('quick_reply_message'::character varying)::text, ('delete_quick_reply_messages'::character varying)::text, ('contacts_reset'::character varying)::text, ('dialog_pinned'::character varying)::text, ('pinned_dialogs'::character varying)::text, ('pinned_messages'::character varying)::text, ('dialog_unread_mark'::character varying)::text, ('peer_settings'::character varying)::text, ('peer_story_blocked'::character varying)::text, ('delete_messages'::character varying)::text, ('dialog_filter'::character varying)::text, ('dialog_filter_order'::character varying)::text, ('dialog_filters'::character varying)::text, ('folder_peers'::character varying)::text, ('channel_view_forum_as_messages'::character varying)::text, ('channel_state'::character varying)::text, ('saved_dialog_pinned'::character varying)::text, ('pinned_saved_dialogs'::character varying)::text, ('story'::character varying)::text, ('read_stories'::character varying)::text, ('sent_story_reaction'::character varying)::text, ('new_story_reaction'::character varying)::text, ('noop'::character varying)::text])))
 );
 
 

deploy/migrations/0003_user_update_events_discussion_types.down.sql

@@ -7,7 +7,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
         'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
         'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
         'peer_settings', 'peer_story_blocked', 'delete_messages', 'dialog_filter', 'dialog_filter_order',
-        'dialog_filters', 'folder_peers', 'channel_available_messages', 'channel_view_forum_as_messages',
+        'dialog_filters', 'folder_peers', 'channel_view_forum_as_messages',
         'channel_state', 'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
         'sent_story_reaction', 'new_story_reaction', 'noop'
     ]::text[])

deploy/migrations/0003_user_update_events_discussion_types.up.sql

@@ -12,7 +12,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
         'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
         'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
         'peer_settings', 'peer_story_blocked', 'delete_messages', 'dialog_filter', 'dialog_filter_order',
-        'dialog_filters', 'folder_peers', 'channel_available_messages', 'channel_view_forum_as_messages',
+        'dialog_filters', 'folder_peers', 'channel_view_forum_as_messages',
         'channel_state', 'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
         'sent_story_reaction', 'new_story_reaction', 'noop',
         'read_channel_discussion_inbox', 'read_channel_discussion_outbox'

deploy/migrations/0015_user_update_events_web_page.down.sql

@@ -7,7 +7,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
         'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
         'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
         'peer_settings', 'peer_story_blocked', 'delete_messages', 'dialog_filter', 'dialog_filter_order',
-        'dialog_filters', 'folder_peers', 'channel_available_messages', 'channel_view_forum_as_messages',
+        'dialog_filters', 'folder_peers', 'channel_view_forum_as_messages',
         'channel_state', 'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
         'sent_story_reaction', 'new_story_reaction', 'noop',
         'read_channel_discussion_inbox', 'read_channel_discussion_outbox'

deploy/migrations/0015_user_update_events_web_page.up.sql

@@ -10,7 +10,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
         'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
         'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
         'peer_settings', 'peer_story_blocked', 'delete_messages', 'dialog_filter', 'dialog_filter_order',
-        'dialog_filters', 'folder_peers', 'channel_available_messages', 'channel_view_forum_as_messages',
+        'dialog_filters', 'folder_peers', 'channel_view_forum_as_messages',
         'channel_state', 'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
         'sent_story_reaction', 'new_story_reaction', 'noop',
         'read_channel_discussion_inbox', 'read_channel_discussion_outbox'

deploy/migrations/0061_user_phone_change_update.down.sql

@@ -6,7 +6,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
         'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
         'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
         'peer_settings', 'peer_story_blocked', 'delete_messages', 'dialog_filter', 'dialog_filter_order',
-        'dialog_filters', 'folder_peers', 'channel_available_messages', 'channel_view_forum_as_messages',
+        'dialog_filters', 'folder_peers', 'channel_view_forum_as_messages',
         'channel_state', 'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
         'sent_story_reaction', 'new_story_reaction', 'noop', 'read_channel_discussion_inbox',
         'read_channel_discussion_outbox'

deploy/migrations/0061_user_phone_change_update.up.sql

@@ -9,7 +9,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
         'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
         'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
         'peer_settings', 'peer_story_blocked', 'user_phone', 'delete_messages', 'dialog_filter',
-        'dialog_filter_order', 'dialog_filters', 'folder_peers', 'channel_available_messages',
+        'dialog_filter_order', 'dialog_filters', 'folder_peers',
         'channel_view_forum_as_messages', 'channel_state', 'saved_dialog_pinned',
         'pinned_saved_dialogs', 'story', 'read_stories', 'sent_story_reaction',
         'new_story_reaction', 'noop', 'read_channel_discussion_inbox',

deploy/migrations/0114_collectible_emoji_status.down.sql

@@ -23,7 +23,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
     'new_quick_reply', 'delete_quick_reply', 'quick_reply_message', 'delete_quick_reply_messages',
     'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
     'peer_settings', 'peer_story_blocked', 'user_phone', 'delete_messages', 'dialog_filter',
-    'dialog_filter_order', 'dialog_filters', 'folder_peers', 'channel_available_messages',
+    'dialog_filter_order', 'dialog_filters', 'folder_peers',
     'channel_view_forum_as_messages', 'channel_state', 'saved_dialog_pinned',
     'pinned_saved_dialogs', 'story', 'read_stories', 'sent_story_reaction',
     'new_story_reaction', 'noop', 'read_channel_discussion_inbox',

deploy/migrations/0114_collectible_emoji_status.up.sql

@@ -50,7 +50,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
     'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
     'peer_settings', 'peer_story_blocked', 'user_phone', 'user_emoji_status', 'delete_messages',
     'dialog_filter', 'dialog_filter_order', 'dialog_filters', 'folder_peers',
-    'channel_available_messages', 'channel_view_forum_as_messages', 'channel_state',
+    'channel_view_forum_as_messages', 'channel_state',
     'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
     'sent_story_reaction', 'new_story_reaction', 'noop',
     'read_channel_discussion_inbox', 'read_channel_discussion_outbox'

deploy/migrations/0147_user_moderation_profile_events.down.sql

@@ -9,7 +9,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
     'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
     'peer_settings', 'peer_story_blocked', 'user_phone', 'user_emoji_status', 'delete_messages',
     'dialog_filter', 'dialog_filter_order', 'dialog_filters', 'folder_peers',
-    'channel_available_messages', 'channel_view_forum_as_messages', 'channel_state',
+    'channel_view_forum_as_messages', 'channel_state',
     'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
     'sent_story_reaction', 'new_story_reaction', 'noop',
     'read_channel_discussion_inbox', 'read_channel_discussion_outbox'

deploy/migrations/0147_user_moderation_profile_events.up.sql

@@ -12,7 +12,7 @@ ALTER TABLE public.user_update_events ADD CONSTRAINT user_update_events_type_che
     'contacts_reset', 'dialog_pinned', 'pinned_dialogs', 'pinned_messages', 'dialog_unread_mark',
     'peer_settings', 'peer_story_blocked', 'user_phone', 'user_emoji_status',
     'delete_messages', 'dialog_filter', 'dialog_filter_order', 'dialog_filters', 'folder_peers',
-    'channel_available_messages', 'channel_view_forum_as_messages', 'channel_state',
+    'channel_view_forum_as_messages', 'channel_state',
     'saved_dialog_pinned', 'pinned_saved_dialogs', 'story', 'read_stories',
     'sent_story_reaction', 'new_story_reaction', 'noop',
     'read_channel_discussion_inbox', 'read_channel_discussion_outbox'

deploy/migrations/0161_channel_history_clear_anchor.down.sql

@@ -0,0 +1,4 @@
+ALTER TABLE channel_members
+    DROP CONSTRAINT IF EXISTS channel_members_history_clear_anchor_check,
+    DROP COLUMN IF EXISTS history_clear_anchor_date,
+    DROP COLUMN IF EXISTS history_clear_anchor_id;

deploy/migrations/0161_channel_history_clear_anchor.up.sql

@@ -0,0 +1,14 @@
+ALTER TABLE channel_members
+    ADD COLUMN history_clear_anchor_id integer DEFAULT 0 NOT NULL,
+    ADD COLUMN history_clear_anchor_date integer DEFAULT 0 NOT NULL,
+    ADD CONSTRAINT channel_members_history_clear_anchor_check CHECK (
+        (
+            history_clear_anchor_id = 0
+            AND history_clear_anchor_date = 0
+        )
+        OR (
+            history_clear_anchor_id > 0
+            AND history_clear_anchor_date > 0
+            AND history_clear_anchor_id <= available_min_id
+        )
+    );

deploy/migrations/0162_channel_history_clear_recovery.down.sql

@@ -0,0 +1,7 @@
+DROP INDEX IF EXISTS user_channel_member_index_history_clear_idx;
+
+ALTER TABLE user_channel_member_index
+    DROP CONSTRAINT IF EXISTS user_channel_member_index_history_clear_check,
+    DROP COLUMN IF EXISTS history_clear_updated_at,
+    DROP COLUMN IF EXISTS history_clear_anchor_id,
+    DROP COLUMN IF EXISTS available_min_id;

deploy/migrations/0162_channel_history_clear_recovery.up.sql

@@ -0,0 +1,22 @@
+ALTER TABLE user_channel_member_index
+    ADD COLUMN available_min_id integer DEFAULT 0 NOT NULL,
+    ADD COLUMN history_clear_anchor_id integer DEFAULT 0 NOT NULL,
+    ADD COLUMN history_clear_updated_at integer DEFAULT 0 NOT NULL,
+    ADD CONSTRAINT user_channel_member_index_history_clear_check CHECK (
+        (
+            history_clear_anchor_id = 0
+            AND history_clear_updated_at = 0
+        )
+        OR (
+            history_clear_anchor_id > 0
+            AND history_clear_updated_at > 0
+            AND history_clear_anchor_id <= available_min_id
+        )
+    );
+
+CREATE INDEX user_channel_member_index_history_clear_idx
+    ON user_channel_member_index (user_id, channel_id)
+    INCLUDE (available_min_id, history_clear_updated_at)
+    WHERE status = 'active'
+      AND NOT deleted
+      AND history_clear_anchor_id > 0;

internal/app/channels/service.go

@@ -2301,7 +2301,16 @@ func (s *Service) GetDifference(ctx context.Context, userID int64, req domain.Ch
 	if err != nil {
 		return domain.ChannelDifference{}, err
 	}
-	return s.filterBotChannelDifference(ctx, userID, diff), nil
+	diff = s.filterBotChannelDifference(ctx, userID, diff)
+	if diff.Self.HistoryClearAnchorID > 0 &&
+		diff.Self.HistoryClearAnchorID == diff.Self.AvailableMinID &&
+		!diff.TooLong {
+		// updateChannelAvailableMessages is an absolute no-PTS update. Keep it
+		// outside ChannelUpdateEvent so channel difference continuity remains
+		// defined solely by real channel events.
+		diff.AvailableMinID = diff.Self.AvailableMinID
+	}
+	return diff, nil
 }
 
 // ClearDanglingPinnedMessage 清除指向已删除消息的悬挂置顶值（unpinAll 自愈）。

internal/app/dialogs/service.go

@@ -408,22 +408,24 @@ func isChannelPreviewAccessError(err error) bool {
 func dialogFromChannelView(view domain.ChannelView) domain.Dialog {
 	dialog := view.Dialog
 	return domain.Dialog{
-		Peer:                domain.Peer{Type: domain.PeerTypeChannel, ID: dialog.ChannelID},
+		Peer:                   domain.Peer{Type: domain.PeerTypeChannel, ID: dialog.ChannelID},
-		ChannelLeft:         view.Self.Status == domain.ChannelMemberLeft,
+		ChannelLeft:            view.Self.Status == domain.ChannelMemberLeft,
-		FolderID:            dialog.FolderID,
+		FolderID:               dialog.FolderID,
-		TopMessage:          dialog.TopMessageID,
+		TopMessage:             dialog.TopMessageID,
-		TopMessageDate:      dialog.TopMessageDate,
+		TopMessageDate:         dialog.TopMessageDate,
-		ReadInboxMaxID:      dialog.ReadInboxMaxID,
+		HistoryClearAnchorID:   dialog.HistoryClearAnchorID,
-		ReadOutboxMaxID:     dialog.ReadOutboxMaxID,
+		HistoryClearAnchorDate: dialog.HistoryClearAnchorDate,
-		UnreadCount:         dialog.UnreadCount,
+		ReadInboxMaxID:         dialog.ReadInboxMaxID,
-		UnreadMentions:      dialog.UnreadMentions,
+		ReadOutboxMaxID:        dialog.ReadOutboxMaxID,
-		UnreadReactions:     dialog.UnreadReactions,
+		UnreadCount:            dialog.UnreadCount,
-		Pinned:              dialog.Pinned,
+		UnreadMentions:         dialog.UnreadMentions,
-		PinnedOrder:         dialog.PinnedOrder,
+		UnreadReactions:        dialog.UnreadReactions,
-		UnreadMark:          dialog.UnreadMark,
+		Pinned:                 dialog.Pinned,
-		ViewForumAsMessages: dialog.ViewForumAsMessages,
+		PinnedOrder:            dialog.PinnedOrder,
-		HasScheduled:        dialog.HasScheduled,
+		UnreadMark:             dialog.UnreadMark,
-		Pts:                 view.Channel.Pts,
+		ViewForumAsMessages:    dialog.ViewForumAsMessages,
+		HasScheduled:           dialog.HasScheduled,
+		Pts:                    view.Channel.Pts,
 	}
 }
 

internal/app/updates/service.go

@@ -731,16 +731,6 @@ func (s *Service) RecordFolderPeers(ctx context.Context, stateAuthKeyID [8]byte,
 	}, true, excludeSessionID)
 }
 
-// RecordChannelAvailableMessages records a local channel history clear for multi-device sync.
-func (s *Service) RecordChannelAvailableMessages(ctx context.Context, stateAuthKeyID [8]byte, userID, channelID int64, availableMinID int, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error) {
-	return s.recordEvent(ctx, stateAuthKeyID, excludeAuthKeyID, userID, domain.UpdateEvent{
-		Type:     domain.UpdateEventChannelAvailable,
-		Peer:     domain.Peer{Type: domain.PeerTypeChannel, ID: channelID},
-		MaxID:    availableMinID,
-		PtsCount: 1,
-	}, true, excludeSessionID)
-}
-
 func (s *Service) recordEvent(ctx context.Context, stateAuthKeyID, excludeAuthKeyID [8]byte, userID int64, event domain.UpdateEvent, dispatch bool, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error) {
 	return s.recordEventCore(ctx, stateAuthKeyID, excludeAuthKeyID, userID, event, dispatch, excludeSessionID, true)
 }

internal/domain/channel.go

@@ -485,23 +485,29 @@ func (c Channel) MembersListAdminOnly() bool {
 
 // ChannelMember is one user's channel membership and read state.
 type ChannelMember struct {
-	ChannelID            int64
+	ChannelID       int64
-	UserID               int64
+	UserID          int64
-	InviterUserID        int64
+	InviterUserID   int64
-	Role                 ChannelMemberRole
+	Role            ChannelMemberRole
-	Status               ChannelMemberStatus
+	Status          ChannelMemberStatus
-	JoinedAt             int
+	JoinedAt        int
-	LeftAt               int
+	LeftAt          int
-	AdminRights          ChannelAdminRights
+	AdminRights     ChannelAdminRights
-	BannedRights         ChannelBannedRights
+	BannedRights    ChannelBannedRights
-	Rank                 string
+	Rank            string
-	AvailableMinID       int
+	AvailableMinID  int
-	AvailableMinPts      int
+	AvailableMinPts int
-	ReadInboxMaxID       int
+	// HistoryClearAnchorID/Date identify an owner-local channels.deleteHistory
-	ReadInboxDate        int
+	// boundary. They are deliberately separate from AvailableMinID: joining a
-	ReadOutboxMaxID      int
+	// hidden-prehistory channel also advances AvailableMinID but must not
-	UnreadMark           bool
+	// manufacture a "History cleared" service message.
-	SlowmodeLastSendDate int
+	HistoryClearAnchorID   int
+	HistoryClearAnchorDate int
+	ReadInboxMaxID         int
+	ReadInboxDate          int
+	ReadOutboxMaxID        int
+	UnreadMark             bool
+	SlowmodeLastSendDate   int
 	// Guest is a computed, non-persisted view used for subscribers accessing a
 	// private linked discussion group without joining it. Guest must never be
 	// written to channel_members and is still projected to clients as left.
@@ -545,22 +551,24 @@ func (m ChannelMember) CanPostChannelMessages() bool {
 
 // ChannelDialog is the current user's owner-view dialog state for a channel.
 type ChannelDialog struct {
-	UserID              int64
+	UserID                 int64
-	ChannelID           int64
+	ChannelID              int64
-	FolderID            int
+	FolderID               int
-	TopMessageID        int
+	TopMessageID           int
-	TopMessageDate      int
+	TopMessageDate         int
-	ReadInboxMaxID      int
+	HistoryClearAnchorID   int
-	ReadOutboxMaxID     int
+	HistoryClearAnchorDate int
-	UnreadCount         int
+	ReadInboxMaxID         int
-	UnreadMentions      int
+	ReadOutboxMaxID        int
-	UnreadReactions     int
+	UnreadCount            int
-	Pinned              bool
+	UnreadMentions         int
-	PinnedOrder         int
+	UnreadReactions        int
-	UnreadMark          bool
+	Pinned                 bool
-	ViewForumAsMessages bool
+	PinnedOrder            int
-	HasScheduled        bool
+	UnreadMark             bool
-	DefaultSendAs       *Peer
+	ViewForumAsMessages    bool
+	HasScheduled           bool
+	DefaultSendAs          *Peer
 }
 
 // ChannelMessageActionType identifies service messages generated by channel operations.
@@ -573,7 +581,11 @@ const (
 	ChannelActionChatDelete      ChannelMessageActionType = "chat_delete_user"
 	ChannelActionChatEditPhoto   ChannelMessageActionType = "chat_edit_photo"
 	ChannelActionChatDeletePhoto ChannelMessageActionType = "chat_delete_photo"
-	ChannelActionChatJoined      ChannelMessageActionType = "chat_joined"
+	// ChannelActionHistoryClear is an owner-local projection at the member's
+	// channels.deleteHistory boundary. It is never persisted into the shared
+	// channel_messages row and never produces channel PTS.
+	ChannelActionHistoryClear ChannelMessageActionType = "history_clear"
+	ChannelActionChatJoined   ChannelMessageActionType = "chat_joined"
 	// ChannelActionChatJoinedByLink 是经邀请链接加入的服务消息，
 	// 渲染为 "X joined the group via invite link"。
 	ChannelActionChatJoinedByLink ChannelMessageActionType = "chat_joined_by_link"
@@ -710,6 +722,39 @@ type ChannelMessage struct {
 	Deleted    bool
 }
 
+// ProjectChannelHistoryClearMessage returns the owner-local service-message
+// projection for one channel history boundary. Identity fields from the shared
+// source are retained when available, while all user payload, media, reply,
+// reaction, pin, TTL and edit state is removed. A zero source is valid for a
+// retained anchor whose shared row has already been physically pruned.
+func ProjectChannelHistoryClearMessage(source ChannelMessage, channelID int64, messageID, messageDate int) ChannelMessage {
+	if source.ChannelID == 0 {
+		source.ChannelID = channelID
+	}
+	if source.ID == 0 {
+		source.ID = messageID
+	}
+	if source.Date == 0 {
+		source.Date = messageDate
+	}
+	return ChannelMessage{
+		ChannelID:    source.ChannelID,
+		ID:           source.ID,
+		SenderUserID: source.SenderUserID,
+		From:         source.From,
+		Date:         source.Date,
+		Post:         source.Post,
+		Silent:       source.Silent,
+		Action:       &ChannelMessageAction{Type: ChannelActionHistoryClear},
+	}
+}
+
+// IsChannelHistoryClearMessage reports whether msg is an owner-local history
+// clear projection rather than a shared channel service message.
+func IsChannelHistoryClearMessage(msg ChannelMessage) bool {
+	return msg.Action != nil && msg.Action.Type == ChannelActionHistoryClear
+}
+
 // MessageReactionType identifies one stored reaction constructor without depending on TL types.
 type MessageReactionType string
 
@@ -1290,19 +1335,27 @@ type ChannelDifference struct {
 	Events       []ChannelUpdateEvent
 	NewMessages  []ChannelMessage
 	OtherUpdates []ChannelUpdateEvent
-	Users        []User
+	// AvailableMinID is an owner-local, absolute no-PTS boundary appended to a
-	Channels     []Channel
+	// normal channel difference. It must never be represented as a synthetic
-	Pts          int
+	// ChannelUpdateEvent because updateChannelAvailableMessages has no pts.
-	Final        bool
+	AvailableMinID int
-	TooLong      bool
+	Users          []User
-	Dialog       ChannelDialog
+	Channels       []Channel
-	Timeout      int
+	Pts            int
+	Final          bool
+	TooLong        bool
+	Dialog         ChannelDialog
+	Timeout        int
 }
 
-// DirtyChannel identifies an active channel with channel-scoped updates after an account difference date.
+// DirtyChannel identifies an active channel with shared channel updates and/or
+// an owner-local no-PTS history-clear boundary after an account difference date.
 type DirtyChannel struct {
-	ChannelID int64
+	ChannelID           int64
-	Pts       int
+	Pts                 int
+	ChannelUpdatesDirty bool
+	AvailableMinID      int
+	HistoryClearDate    int
 }
 
 // ChannelUpdateRetentionCheckpoint is the durable recovery boundary for one channel.
@@ -1980,6 +2033,9 @@ type DeleteChannelHistoryResult struct {
 	Recipients     []int64
 	Offset         int
 	AvailableMinID int
+	// AvailableMinChanged is true only when this owner-local request advanced
+	// the member boundary and installed a new history-clear anchor.
+	AvailableMinChanged bool
 }
 
 // UpdateChannelPinnedMessageRequest pins or unpins one channel/supergroup message.
@@ -2192,6 +2248,10 @@ type ChannelHistoryFilter struct {
 	SenderUserID int64
 	PinnedOnly   bool
 	MusicOnly    bool
+	// IncludeHistoryClearAnchor is set only by messages.getHistory. Search,
+	// media and topic projections must not count the owner-local service marker
+	// as shared channel content.
+	IncludeHistoryClearAnchor bool
 	// NeedTotalCount requests the exact number of messages matching the static
 	// filters before offset/add_offset pagination. Ordinary history pages leave
 	// this false and keep the bounded len(page)+has-more hint.

internal/domain/dialog.go

@@ -69,24 +69,29 @@ func (p Peer) IsSelfUser(userID int64) bool {
 
 // Dialog 是账号的一条会话摘要。
 type Dialog struct {
-	Peer                  Peer
+	Peer           Peer
-	ChannelLeft           bool
+	ChannelLeft    bool
-	FolderID              int
+	FolderID       int
-	TopMessage            int
+	TopMessage     int
-	TopMessageDate        int
+	TopMessageDate int
-	ReadInboxMaxID        int
+	// HistoryClearAnchorID/Date are internal owner-view projection metadata.
-	ReadOutboxMaxID       int
+	// They are not TL dialog fields; dialog response assembly uses them to
-	UnreadCount           int
+	// materialize the matching messageActionHistoryClear top payload.
-	UnreadMentions        int
+	HistoryClearAnchorID   int
-	UnreadReactions       int
+	HistoryClearAnchorDate int
-	TTLPeriod             int
+	ReadInboxMaxID         int
-	ThemeEmoticon         string
+	ReadOutboxMaxID        int
-	HasScheduled          bool
+	UnreadCount            int
-	Pinned                bool
+	UnreadMentions         int
-	PinnedOrder           int
+	UnreadReactions        int
-	UnreadMark            bool
+	TTLPeriod              int
-	ViewForumAsMessages   bool
+	ThemeEmoticon          string
-	PeerSettingsBarHidden bool
+	HasScheduled           bool
+	Pinned                 bool
+	PinnedOrder            int
+	UnreadMark             bool
+	ViewForumAsMessages    bool
+	PeerSettingsBarHidden  bool
 	// Pts 是 channel peer 当前 channel pts；客户端用 dialog.pts 初始化本地
 	// channel 序列并决定 getChannelDifference 起点，channel dialog 必填。
 	Pts   int

internal/domain/update_event.go

@@ -44,7 +44,6 @@ const (
 	UpdateEventDialogFilterOrder        UpdateEventType = "dialog_filter_order"
 	UpdateEventDialogFilters            UpdateEventType = "dialog_filters"
 	UpdateEventFolderPeers              UpdateEventType = "folder_peers"
-	UpdateEventChannelAvailable         UpdateEventType = "channel_available_messages"
 	UpdateEventChannelViewForum         UpdateEventType = "channel_view_forum_as_messages"
 	UpdateEventStory                    UpdateEventType = "story"
 	UpdateEventReadStories              UpdateEventType = "read_stories"
@@ -141,7 +140,6 @@ func (e UpdateEvent) LacksWirePts() bool {
 		UpdateEventDialogFilter,
 		UpdateEventDialogFilterOrder,
 		UpdateEventDialogFilters,
-		UpdateEventChannelAvailable,
 		UpdateEventChannelViewForum,
 		UpdateEventStory,
 		UpdateEventReadStories,
@@ -178,7 +176,10 @@ type UpdateDifference struct {
 
 // ChannelDifferenceNudge is a computed account-level hint that a channel diff is dirty.
 type ChannelDifferenceNudge struct {
-	ChannelID int64
+	ChannelID           int64
-	Pts       int
+	Pts                 int
-	Channel   *ChannelView
+	ChannelUpdatesDirty bool
+	AvailableMinID      int
+	HistoryClearDate    int
+	Channel             *ChannelView
 }

internal/rpc/channels_messages.go

@@ -394,10 +394,14 @@ func (r *Router) onChannelsDeleteHistory(ctx context.Context, req *tg.ChannelsDe
 		return nil, channelDeleteErr(err)
 	}
 	if res.Event.Pts == 0 {
-		event := r.recordChannelAvailableMessages(ctx, userID, res.Channel.ID, res.AvailableMinID)
+		updates := r.channelAvailableMessagesUpdates(userID, res.Channel, res.AvailableMinID)
-		updates := r.channelAvailableMessagesUpdates(userID, res.Channel, event.MaxID)
+		if res.AvailableMinChanged {
-		updates.Updates = appendAuxPtsBookkeeping(updates.Updates, event)
+			// updateChannelAvailableMessages is an absolute owner-local boundary
-		r.pushUserUpdates(ctx, userID, updates)
+			// with no account/channel pts. Other online sessions consume it
+			// immediately; future cold/offline sessions discover the same
+			// boundary through account/channel difference recovery.
+			r.pushUserUpdates(ctx, userID, updates)
+		}
 		return updates, nil
 	}
 	pushBatch := func(batch domain.DeleteChannelHistoryResult) *tg.Updates {

internal/rpc/channels_messages_rpc_test.go

@@ -174,6 +174,7 @@ func TestChannelsDeleteHistoryLocalClearEmitsAvailableMessagesUpdate(t *testing.
 	r := New(Config{}, Deps{
 		Users:    appusers.NewService(userStore),
 		Channels: appchannels.NewService(channelStore),
+		Dialogs:  appdialogs.NewService(memory.NewDialogStore(), channelStore),
 		Updates:  updateSvc,
 		Sessions: sessions,
 	}, zaptest.NewLogger(t), clock.System)
@@ -193,7 +194,14 @@ func TestChannelsDeleteHistoryLocalClearEmitsAvailableMessagesUpdate(t *testing.
 	if err != nil {
 		t.Fatalf("send channel message: %v", err)
 	}
-	msg := sent.(*tg.Updates).Updates[1].(*tg.UpdateNewChannelMessage).Message.(*tg.Message)
+	newChannelUpdate := sent.(*tg.Updates).Updates[1].(*tg.UpdateNewChannelMessage)
+	msg := newChannelUpdate.Message.(*tg.Message)
+	clearSince := int(time.Now().Unix()) - 1
+	stateBefore, err := updateSvc.CurrentState(ctx, owner.ID)
+	if err != nil {
+		t.Fatalf("account state before clear: %v", err)
+	}
+	pushesBefore := len(sessions.pushedUserIDs())
 	cleared, err := r.onChannelsDeleteHistory(WithUserID(ctx, owner.ID), &tg.ChannelsDeleteHistoryRequest{
 		Channel: &tg.InputChannel{ChannelID: channel.ID, AccessHash: channel.AccessHash},
 		MaxID:   msg.ID,
@@ -202,42 +210,144 @@ func TestChannelsDeleteHistoryLocalClearEmitsAvailableMessagesUpdate(t *testing.
 		t.Fatalf("delete channel history local: %v", err)
 	}
 	updates, ok := cleared.(*tg.Updates)
-	if !ok || len(updates.Updates) != 2 {
+	if !ok || len(updates.Updates) != 1 {
-		t.Fatalf("clear response = %T %+v, want available update plus pts bookkeeping", cleared, cleared)
+		t.Fatalf("clear response = %T %+v, want one no-pts available update", cleared, cleared)
 	}
 	available, ok := updates.Updates[0].(*tg.UpdateChannelAvailableMessages)
 	if !ok || available.ChannelID != channel.ID || available.AvailableMinID != msg.ID {
 		t.Fatalf("clear update = %#v, want updateChannelAvailableMessages channel=%d min=%d", updates.Updates[0], channel.ID, msg.ID)
 	}
-	// updateChannelAvailableMessages 不带账号 pts，事件占用的 pts 槽位
+	stateAfter, err := updateSvc.CurrentState(ctx, owner.ID)
-	// 必须用空 updateDeleteMessages 显式同步给客户端。
+	if err != nil {
-	bookkeeping, ok := updates.Updates[1].(*tg.UpdateDeleteMessages)
+		t.Fatalf("account state after clear: %v", err)
-	if !ok || len(bookkeeping.Messages) != 0 || bookkeeping.Pts <= 0 || bookkeeping.PtsCount != 1 {
+	}
-		t.Fatalf("clear bookkeeping = %#v, want empty updateDeleteMessages carrying the account pts step", updates.Updates[1])
+	if stateAfter.Pts != stateBefore.Pts {
+		t.Fatalf("account pts advanced on local channel clear: before=%d after=%d", stateBefore.Pts, stateAfter.Pts)
 	}
 	pushed := sessions.snapshot()
 	if pushed.userID != owner.ID {
 		t.Fatalf("pushed user = %d, want owner %d", pushed.userID, owner.ID)
 	}
 	pushedUpdates, ok := pushed.message.(*tg.Updates)
-	if !ok || len(pushedUpdates.Updates) != 2 {
+	if !ok || len(pushedUpdates.Updates) != 1 {
-		t.Fatalf("pushed clear update = %T %+v, want available update plus pts bookkeeping", pushed.message, pushed.message)
+		t.Fatalf("pushed clear update = %T %+v, want one no-pts available update", pushed.message, pushed.message)
 	}
 	if _, ok := pushedUpdates.Updates[0].(*tg.UpdateChannelAvailableMessages); !ok {
 		t.Fatalf("pushed update[0] = %T, want updateChannelAvailableMessages", pushedUpdates.Updates[0])
 	}
-	diff, err := r.onUpdatesGetDifference(WithUserID(ctx, owner.ID), &tg.UpdatesGetDifferenceRequest{Pts: 0})
+	if got := len(sessions.pushedUserIDs()) - pushesBefore; got != 1 {
+		t.Fatalf("clear online pushes = %d, want exactly one owner-session fanout", got)
+	}
+	diff, err := updateSvc.GetDifference(ctx, [8]byte{}, owner.ID, stateBefore)
 	if err != nil {
 		t.Fatalf("get difference: %v", err)
 	}
-	full, ok := diff.(*tg.UpdatesDifference)
+	if len(diff.Events) != 0 || diff.State.Pts != stateBefore.Pts {
-	if !ok || len(full.OtherUpdates) != 1 {
+		t.Fatalf("difference after no-pts clear = %+v, want no durable account event", diff)
-		t.Fatalf("difference = %T %+v, want one other update", diff, diff)
 	}
-	if diffUpdate, ok := full.OtherUpdates[0].(*tg.UpdateChannelAvailableMessages); !ok || diffUpdate.ChannelID != channel.ID || diffUpdate.AvailableMinID != msg.ID {
+	offline, err := r.onUpdatesGetDifference(WithUserID(ctx, owner.ID), &tg.UpdatesGetDifferenceRequest{
-		t.Fatalf("difference update = %#v, want updateChannelAvailableMessages", full.OtherUpdates[0])
+		Pts:  stateBefore.Pts,
+		Date: clearSince,
+	})
+	if err != nil {
+		t.Fatalf("account difference after offline local clear: %v", err)
+	}
+	offlineDiff, ok := offline.(*tg.UpdatesDifference)
+	if !ok {
+		t.Fatalf("offline account difference = %T %+v, want updates.difference", offline, offline)
+	}
+	var accountAvailable *tg.UpdateChannelAvailableMessages
+	for _, update := range offlineDiff.OtherUpdates {
+		if value, ok := update.(*tg.UpdateChannelAvailableMessages); ok {
+			accountAvailable = value
+			break
+		}
+	}
+	if accountAvailable == nil ||
+		accountAvailable.ChannelID != channel.ID ||
+		accountAvailable.AvailableMinID != msg.ID {
+		t.Fatalf("offline account updates = %+v, want updateChannelAvailableMessages channel=%d min=%d",
+			offlineDiff.OtherUpdates, channel.ID, msg.ID)
+	}
+	if offlineDiff.State.Pts != stateBefore.Pts || offlineDiff.State.Date < clearSince {
+		t.Fatalf("offline account state = %+v, want unchanged pts=%d and non-regressing date", offlineDiff.State, stateBefore.Pts)
 	}
 
+	channelOffline, err := r.onUpdatesGetChannelDifference(WithUserID(ctx, owner.ID), &tg.UpdatesGetChannelDifferenceRequest{
+		Channel: &tg.InputChannel{ChannelID: channel.ID, AccessHash: channel.AccessHash},
+		Filter:  &tg.ChannelMessagesFilterEmpty{},
+		Pts:     newChannelUpdate.Pts,
+		Limit:   100,
+	})
+	if err != nil {
+		t.Fatalf("channel difference after offline local clear: %v", err)
+	}
+	channelDiff, ok := channelOffline.(*tg.UpdatesChannelDifference)
+	if !ok {
+		t.Fatalf("offline channel difference = %T %+v, want non-empty difference with absolute update", channelOffline, channelOffline)
+	}
+	var channelAvailable *tg.UpdateChannelAvailableMessages
+	for _, update := range channelDiff.OtherUpdates {
+		if value, ok := update.(*tg.UpdateChannelAvailableMessages); ok {
+			channelAvailable = value
+			break
+		}
+	}
+	if channelAvailable == nil ||
+		channelAvailable.ChannelID != channel.ID ||
+		channelAvailable.AvailableMinID != msg.ID ||
+		channelDiff.Pts != newChannelUpdate.Pts {
+		t.Fatalf("offline channel updates = %+v pts=%d, want available boundary %d with unchanged channel pts=%d",
+			channelDiff.OtherUpdates, channelDiff.Pts, msg.ID, newChannelUpdate.Pts)
+	}
+
+	req := &tg.MessagesGetDialogsRequest{OffsetPeer: &tg.InputPeerEmpty{}, Limit: 20}
+	var b bin.Buffer
+	if err := req.Encode(&b); err != nil {
+		t.Fatalf("encode get dialogs after clear: %v", err)
+	}
+	enc, err := r.Dispatch(WithUserID(ctx, owner.ID), [8]byte{}, 0, &b)
+	if err != nil {
+		t.Fatalf("dispatch get dialogs after clear: %v", err)
+	}
+	dialogs, ok := enc.(*tg.MessagesDialogs)
+	if !ok || len(dialogs.Dialogs) != 1 || len(dialogs.Messages) != 1 {
+		t.Fatalf("dialogs after cold projection = %T %+v, want one anchored dialog/message", enc, enc)
+	}
+	dialog := dialogs.Dialogs[0].(*tg.Dialog)
+	service, ok := dialogs.Messages[0].(*tg.MessageService)
+	if !ok || dialog.TopMessage != msg.ID || service.ID != msg.ID {
+		t.Fatalf("cold dialog projection = dialog=%+v message=%T %+v, want history-clear top %d", dialog, dialogs.Messages[0], dialogs.Messages[0], msg.ID)
+	}
+	if _, ok := service.Action.(*tg.MessageActionHistoryClear); !ok {
+		t.Fatalf("cold dialog service action = %T, want messageActionHistoryClear", service.Action)
+	}
+
+	historyReq := &tg.MessagesGetHistoryRequest{
+		Peer:  &tg.InputPeerChannel{ChannelID: channel.ID, AccessHash: channel.AccessHash},
+		Limit: 20,
+	}
+	b.Reset()
+	if err := historyReq.Encode(&b); err != nil {
+		t.Fatalf("encode get history after clear: %v", err)
+	}
+	historyEnc, err := r.Dispatch(WithUserID(ctx, owner.ID), [8]byte{}, 0, &b)
+	if err != nil {
+		t.Fatalf("dispatch get history after clear: %v", err)
+	}
+	history, ok := historyEnc.(*tg.MessagesChannelMessages)
+	if !ok || len(history.Messages) != 1 {
+		t.Fatalf("history after cold projection = %T %+v, want one history-clear marker", historyEnc, historyEnc)
+	}
+	historyService, ok := history.Messages[0].(*tg.MessageService)
+	if !ok || historyService.ID != msg.ID {
+		t.Fatalf("cold history projection = %T %+v, want service marker %d", history.Messages[0], history.Messages[0], msg.ID)
+	}
+	if _, ok := historyService.Action.(*tg.MessageActionHistoryClear); !ok {
+		t.Fatalf("cold history service action = %T, want messageActionHistoryClear", historyService.Action)
+	}
+
+	stalePushesBefore := len(sessions.pushedUserIDs())
 	stale, err := r.onChannelsDeleteHistory(WithUserID(ctx, owner.ID), &tg.ChannelsDeleteHistoryRequest{
 		Channel: &tg.InputChannel{ChannelID: channel.ID, AccessHash: channel.AccessHash},
 		MaxID:   msg.ID - 1,
@@ -246,13 +356,16 @@ func TestChannelsDeleteHistoryLocalClearEmitsAvailableMessagesUpdate(t *testing.
 		t.Fatalf("stale delete channel history local: %v", err)
 	}
 	staleUpdates, ok := stale.(*tg.Updates)
-	if !ok || len(staleUpdates.Updates) != 2 {
+	if !ok || len(staleUpdates.Updates) != 1 {
-		t.Fatalf("stale clear response = %T %+v, want monotonic update plus pts bookkeeping", stale, stale)
+		t.Fatalf("stale clear response = %T %+v, want monotonic absolute update", stale, stale)
 	}
 	staleAvailable, ok := staleUpdates.Updates[0].(*tg.UpdateChannelAvailableMessages)
 	if !ok || staleAvailable.ChannelID != channel.ID || staleAvailable.AvailableMinID != msg.ID {
 		t.Fatalf("stale clear update = %#v, want monotonic updateChannelAvailableMessages channel=%d min=%d", staleUpdates.Updates[0], channel.ID, msg.ID)
 	}
+	if got := len(sessions.pushedUserIDs()); got != stalePushesBefore {
+		t.Fatalf("stale clear pushed another online update: before=%d after=%d", stalePushesBefore, got)
+	}
 }
 
 func TestChannelDeleteRejectsInvalidMessageIDsRPC(t *testing.T) {

internal/rpc/channels_stubs.go

@@ -290,27 +290,6 @@ func peerIDsExcept(ids []int64, skipIDs ...int64) []int64 {
 
 type channelFanoutScope int
 
-func (r *Router) recordChannelAvailableMessages(ctx context.Context, userID, channelID int64, availableMinID int) domain.UpdateEvent {
-	event := domain.UpdateEvent{
-		UserID:   userID,
-		Type:     domain.UpdateEventChannelAvailable,
-		Date:     int(r.clock.Now().Unix()),
-		Peer:     domain.Peer{Type: domain.PeerTypeChannel, ID: channelID},
-		MaxID:    availableMinID,
-		PtsCount: 1,
-	}
-	if r.deps.Updates == nil || userID == 0 || channelID == 0 || availableMinID <= 0 {
-		return event
-	}
-	authKeyID, _ := AuthKeyIDFrom(ctx)
-	sessionID, _ := SessionIDFrom(ctx)
-	recorded, _, err := r.deps.Updates.RecordChannelAvailableMessages(ctx, authKeyID, userID, channelID, availableMinID, rawAuthKeyIDForOrigin(ctx), sessionID)
-	if err != nil {
-		return event
-	}
-	return recorded
-}
-
 func (r *Router) recordChannelReadInbox(ctx context.Context, userID int64, read domain.ReadChannelHistoryResult) (domain.UpdateEvent, error) {
 	if !read.Changed || read.ChannelID == 0 {
 		return domain.UpdateEvent{}, nil

internal/rpc/convert_channels_core.go

@@ -222,6 +222,8 @@ func tgChannelMessageAction(action domain.ChannelMessageAction) tg.MessageAction
 	switch action.Type {
 	case domain.ChannelActionCreate:
 		return &tg.MessageActionChannelCreate{Title: action.Title}
+	case domain.ChannelActionHistoryClear:
+		return &tg.MessageActionHistoryClear{}
 	case domain.ChannelActionChatAddUser, domain.ChannelActionChatJoined:
 		return &tg.MessageActionChatAddUser{Users: append([]int64(nil), action.UserIDs...)}
 	case domain.ChannelActionChatJoinedByLink:

internal/rpc/convert_updates.go

@@ -55,11 +55,23 @@ func tgUpdatesDifference(viewerUserID int64, diff domain.UpdateDifference) tg.Up
 		if nudge.ChannelID == 0 {
 			continue
 		}
-		update := &tg.UpdateChannelTooLong{ChannelID: nudge.ChannelID}
+		if nudge.AvailableMinID > 0 {
-		if nudge.Pts > 0 {
+			out.OtherUpdates = append(out.OtherUpdates, &tg.UpdateChannelAvailableMessages{
-			update.SetPts(nudge.Pts)
+				ChannelID:      nudge.ChannelID,
+				AvailableMinID: nudge.AvailableMinID,
+			})
+		}
+		// Preserve compatibility for older domain callers that only supplied
+		// Pts: a nudge without an owner-local boundary is a shared channel
+		// update nudge. New store results set ChannelUpdatesDirty explicitly so
+		// a channel can carry both absolute clear and too-long updates.
+		if nudge.ChannelUpdatesDirty || nudge.AvailableMinID == 0 {
+			update := &tg.UpdateChannelTooLong{ChannelID: nudge.ChannelID}
+			if nudge.Pts > 0 {
+				update.SetPts(nudge.Pts)
+			}
+			out.OtherUpdates = append(out.OtherUpdates, update)
 		}
-		out.OtherUpdates = append(out.OtherUpdates, update)
 		if nudge.Channel != nil && nudge.Channel.Channel.ID != 0 {
 			addChannelNudgeChat(out, seenChats, tgChannelChatForView(viewerUserID, *nudge.Channel))
 		}
@@ -110,7 +122,7 @@ func tgChannelDifference(viewerUserID int64, diff domain.ChannelDifference) tg.U
 			Users:    tgUsersForViewer(viewerUserID, diff.Users),
 		}
 	}
-	if len(diff.Events) == 0 && len(diff.NewMessages) == 0 && len(diff.OtherUpdates) == 0 {
+	if len(diff.Events) == 0 && len(diff.NewMessages) == 0 && len(diff.OtherUpdates) == 0 && diff.AvailableMinID == 0 {
 		return &tg.UpdatesChannelDifferenceEmpty{
 			Final:   diff.Final,
 			Pts:     diff.Pts,
@@ -136,6 +148,12 @@ func tgChannelDifference(viewerUserID int64, diff domain.ChannelDifference) tg.U
 			updates = append(updates, update)
 		}
 	}
+	if diff.AvailableMinID > 0 {
+		updates = append(updates, &tg.UpdateChannelAvailableMessages{
+			ChannelID:      diff.Channel.ID,
+			AvailableMinID: diff.AvailableMinID,
+		})
+	}
 	chats := tgChannelDifferenceChats(viewerUserID, diff)
 	users := tgUsersForViewer(viewerUserID, diff.Users)
 	return &tg.UpdatesChannelDifference{
@@ -483,14 +501,6 @@ func tgOtherUpdateFromEvent(event domain.UpdateEvent) tg.UpdateClass {
 			Pts:         event.Pts,
 			PtsCount:    event.PtsCount,
 		}
-	case domain.UpdateEventChannelAvailable:
-		if event.Peer.Type != domain.PeerTypeChannel || event.Peer.ID == 0 || event.MaxID <= 0 {
-			return nil
-		}
-		return &tg.UpdateChannelAvailableMessages{
-			ChannelID:      event.Peer.ID,
-			AvailableMinID: event.MaxID,
-		}
 	default:
 		return nil
 	}

internal/rpc/deps.go

@@ -496,7 +496,6 @@ type UpdatesService interface {
 	RecordDialogFilterOrder(ctx context.Context, stateAuthKeyID [8]byte, userID int64, order []int, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)
 	RecordDialogFiltersReload(ctx context.Context, stateAuthKeyID [8]byte, userID int64, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)
 	RecordFolderPeers(ctx context.Context, stateAuthKeyID [8]byte, userID int64, peers []domain.FolderPeerUpdate, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)
-	RecordChannelAvailableMessages(ctx context.Context, stateAuthKeyID [8]byte, userID, channelID int64, availableMinID int, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)
 	RecordChannelViewForumAsMessages(ctx context.Context, stateAuthKeyID [8]byte, userID, channelID int64, enabled bool, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)
 	RecordChannelDiscussionInbox(ctx context.Context, stateAuthKeyID [8]byte, userID, channelID int64, topicID, maxID int, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)
 	RecordDraftMessage(ctx context.Context, stateAuthKeyID [8]byte, userID int64, peer domain.Peer, topMsgID int, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error)

internal/rpc/messages_delete.go

@@ -74,16 +74,13 @@ func (r *Router) onMessagesDeleteHistory(ctx context.Context, req *tg.MessagesDe
 			})
 			return &tg.MessagesAffectedHistory{Pts: res.Event.Pts, PtsCount: res.Event.PtsCount, Offset: res.Offset}, nil
 		}
-		if res.AvailableMinID > 0 {
+		if res.AvailableMinChanged && res.AvailableMinID > 0 {
-			event := r.recordChannelAvailableMessages(ctx, userID, res.Channel.ID, res.AvailableMinID)
+			updates := r.channelAvailableMessagesUpdates(userID, res.Channel, res.AvailableMinID)
-			updates := r.channelAvailableMessagesUpdates(userID, res.Channel, event.MaxID)
-			updates.Updates = appendAuxPtsBookkeeping(updates.Updates, event)
 			r.pushUserUpdates(ctx, userID, updates)
-			if event.Pts != 0 {
-				return &tg.MessagesAffectedHistory{Pts: event.Pts, PtsCount: event.PtsCount, Offset: res.Offset}, nil
-			}
 		}
-		return &tg.MessagesAffectedHistory{Pts: res.Channel.Pts, PtsCount: 0, Offset: res.Offset}, nil
+		// messages.affectedHistory.pts is the caller's account-state snapshot.
+		// The local channel clear itself consumes no account/channel pts.
+		return r.affectedHistory(ctx, authKeyID, userID, res.Offset)
 	}
 	if peer.Type != domain.PeerTypeUser {
 		return nil, peerIDInvalidErr()

internal/rpc/messages_delete_rpc_test.go

@@ -7,11 +7,74 @@ import (
 	"github.com/iamxvbaba/td/tg"
 	"go.uber.org/zap/zaptest"
 	appchannels "telesrv/internal/app/channels"
+	appupdates "telesrv/internal/app/updates"
 	"telesrv/internal/domain"
 	"telesrv/internal/store/memory"
 	"testing"
 )
 
+func TestMessagesDeleteHistoryChannelLocalClearReturnsAccountStateWithoutPTS(t *testing.T) {
+	ctx := context.Background()
+	channelStore := memory.NewChannelStore()
+	created, err := channelStore.CreateChannel(ctx, domain.CreateChannelRequest{
+		CreatorUserID: 7,
+		Title:         "local clear no pts",
+		Megagroup:     true,
+		Date:          1_700_002_100,
+	})
+	if err != nil {
+		t.Fatalf("create channel: %v", err)
+	}
+	sent, err := channelStore.SendChannelMessage(ctx, domain.SendChannelMessageRequest{
+		UserID:    7,
+		ChannelID: created.Channel.ID,
+		RandomID:  210_001,
+		Message:   "clear locally",
+		Date:      1_700_002_101,
+	})
+	if err != nil {
+		t.Fatalf("send channel message: %v", err)
+	}
+	updateSvc := appupdates.NewService(memory.NewUpdateStateStore(), memory.NewUpdateEventStore())
+	stateBefore, err := updateSvc.CurrentState(ctx, 7)
+	if err != nil {
+		t.Fatalf("account state before clear: %v", err)
+	}
+	sessions := &captureSessions{}
+	r := New(Config{}, Deps{
+		Channels: appchannels.NewService(channelStore),
+		Updates:  updateSvc,
+		Sessions: sessions,
+	}, zaptest.NewLogger(t), clock.System)
+
+	affected, err := r.onMessagesDeleteHistory(WithUserID(ctx, 7), &tg.MessagesDeleteHistoryRequest{
+		Peer:  &tg.InputPeerChannel{ChannelID: created.Channel.ID, AccessHash: created.Channel.AccessHash},
+		MaxID: sent.Message.ID,
+	})
+	if err != nil {
+		t.Fatalf("messages.deleteHistory local channel: %v", err)
+	}
+	if affected.Pts != stateBefore.Pts || affected.PtsCount != 0 || affected.Offset != 0 {
+		t.Fatalf("affected history = %+v, want account pts=%d pts_count=0 offset=0", affected, stateBefore.Pts)
+	}
+	stateAfter, err := updateSvc.CurrentState(ctx, 7)
+	if err != nil {
+		t.Fatalf("account state after clear: %v", err)
+	}
+	if stateAfter.Pts != stateBefore.Pts {
+		t.Fatalf("local channel clear advanced account pts: before=%d after=%d", stateBefore.Pts, stateAfter.Pts)
+	}
+	pushed := sessions.snapshot()
+	updates, ok := pushed.message.(*tg.Updates)
+	if !ok || len(updates.Updates) != 1 {
+		t.Fatalf("pushed local clear = %T %+v, want one available update", pushed.message, pushed.message)
+	}
+	available, ok := updates.Updates[0].(*tg.UpdateChannelAvailableMessages)
+	if !ok || available.ChannelID != created.Channel.ID || available.AvailableMinID != sent.Message.ID {
+		t.Fatalf("available update = %#v, want channel=%d min=%d", updates.Updates[0], created.Channel.ID, sent.Message.ID)
+	}
+}
+
 func TestMessagesDeleteHistoryChannelReturnsOffsetForBoundedPage(t *testing.T) {
 	ctx := context.Background()
 	userStore := memory.NewUserStore()

internal/rpc/messages_register.go

@@ -604,14 +604,15 @@ func (r *Router) registerMessages(d *tlprofile.Dispatcher) {
 				return &tg.MessagesMessages{}, nil
 			}
 			history, err := r.deps.Channels.GetHistory(ctx, userID, domain.ChannelHistoryFilter{
-				ChannelID:  filter.Peer.ID,
+				ChannelID:                 filter.Peer.ID,
-				OffsetID:   filter.OffsetID,
+				OffsetID:                  filter.OffsetID,
-				OffsetDate: filter.OffsetDate,
+				OffsetDate:                filter.OffsetDate,
-				AddOffset:  filter.AddOffset,
+				AddOffset:                 filter.AddOffset,
-				Limit:      filter.Limit,
+				Limit:                     filter.Limit,
-				MaxID:      filter.MaxID,
+				MaxID:                     filter.MaxID,
-				MinID:      filter.MinID,
+				MinID:                     filter.MinID,
-				Hash:       filter.Hash,
+				Hash:                      filter.Hash,
+				IncludeHistoryClearAnchor: true,
 			})
 			if err != nil {
 				return nil, channelInvalidErr(err)

internal/rpc/rpc_testkit_updates_test.go

@@ -284,15 +284,6 @@ func (s *captureUpdates) RecordFolderPeers(_ context.Context, authKeyID [8]byte,
 	return s.recordCapturedEvent(authKeyID, userID, domain.UpdateEvent{Type: domain.UpdateEventFolderPeers, FolderPeers: append([]domain.FolderPeerUpdate(nil), peers...)})
 }
 
-func (s *captureUpdates) RecordChannelAvailableMessages(_ context.Context, authKeyID [8]byte, userID, channelID int64, availableMinID int, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error) {
-	s.captureExclude(excludeAuthKeyID, excludeSessionID)
-	return s.recordCapturedEvent(authKeyID, userID, domain.UpdateEvent{
-		Type:  domain.UpdateEventChannelAvailable,
-		Peer:  domain.Peer{Type: domain.PeerTypeChannel, ID: channelID},
-		MaxID: availableMinID,
-	})
-}
-
 func (s *captureUpdates) RecordChannelViewForumAsMessages(_ context.Context, authKeyID [8]byte, userID, channelID int64, enabled bool, excludeAuthKeyID [8]byte, excludeSessionID int64) (domain.UpdateEvent, domain.UpdateState, error) {
 	s.captureExclude(excludeAuthKeyID, excludeSessionID)
 	return s.recordCapturedEvent(authKeyID, userID, domain.UpdateEvent{

internal/rpc/updates.go

@@ -102,6 +102,21 @@ func (r *Router) onUpdatesGetDifference(ctx context.Context, req *tg.UpdatesGetD
 		return nil, internalErr()
 	}
 	st.ChannelNudges = r.accountChannelDifferenceNudges(ctx, userID, req.Date)
+	if !st.Partial {
+		for _, nudge := range st.ChannelNudges {
+			if nudge.AvailableMinID <= 0 {
+				continue
+			}
+			// No-PTS owner-local clear recovery is date-indexed. Advance only
+			// on the final account page and never beyond the server clock; the
+			// indexed query deliberately overlaps equality, so a same-second
+			// reconnect can receive an idempotent duplicate rather than miss.
+			if now := int(r.clock.Now().Unix()); now > st.State.Date {
+				st.State.Date = now
+			}
+			break
+		}
+	}
 	// 密聊设备级 qts 消息（独立于账号级 pts 事件）：按当前设备 req.Qts 补回。
 	encMsgs, newQts := r.encryptedDifference(ctx, req.Qts)
 	// 密聊握手/已读状态事件（无 qts）：按未投递标记补回 OtherUpdates。
@@ -154,10 +169,19 @@ func (r *Router) accountChannelDifferenceNudges(ctx context.Context, userID int6
 			}
 		}
 		for _, item := range dirty {
+			if len(out) >= maxNudges {
+				break
+			}
 			if item.ChannelID == 0 {
 				continue
 			}
-			nudge := domain.ChannelDifferenceNudge{ChannelID: item.ChannelID, Pts: item.Pts}
+			nudge := domain.ChannelDifferenceNudge{
+				ChannelID:           item.ChannelID,
+				Pts:                 item.Pts,
+				ChannelUpdatesDirty: item.ChannelUpdatesDirty,
+				AvailableMinID:      item.AvailableMinID,
+				HistoryClearDate:    item.HistoryClearDate,
+			}
 			if view, ok := viewsByID[item.ChannelID]; ok {
 				nudge.Channel = &view
 			}

internal/store/memory/channel_dialogs.go

@@ -95,8 +95,8 @@ func (s *ChannelStore) ListChannelDialogs(_ context.Context, viewerUserID int64,
 		out.Dialogs = append(out.Dialogs, dialog)
 		channel := s.channels[dialog.Peer.ID]
 		out.Channels = append(out.Channels, channel)
-		if msg, ok := s.findMessageLocked(dialog.Peer.ID, dialog.TopMessage); ok && !msg.Deleted {
+		if msg, ok := s.channelMessageForMemberLocked(viewerUserID, dialog.Peer.ID, dialog.TopMessage); ok {
-			out.Messages = append(out.Messages, cloneChannelMessage(msg))
+			out.Messages = append(out.Messages, msg)
 		}
 	}
 	// 与 PG 同因：getDialogs top message 按 viewer 补未读提及标志。
@@ -151,8 +151,8 @@ func (s *ChannelStore) GetChannelDialogs(_ context.Context, viewerUserID int64,
 				out.Channels = append(out.Channels, cloneChannel(parent))
 			}
 		}
-		if msg, ok := s.findMessageLocked(channelID, dialog.TopMessage); ok && !msg.Deleted {
+		if msg, ok := s.channelMessageForMemberLocked(viewerUserID, channelID, dialog.TopMessage); ok {
-			out.Messages = append(out.Messages, cloneChannelMessage(msg))
+			out.Messages = append(out.Messages, msg)
 		}
 	}
 	out.Count = len(out.Dialogs)
@@ -470,36 +470,47 @@ func channelDialogToDialog(dialog domain.ChannelDialog, channelPts int, memberSt
 	return domain.Dialog{
 		Peer: domain.Peer{Type: domain.PeerTypeChannel, ID: dialog.ChannelID},
 		// 非成员预览(publicPreviewMember/被踢)须标记 ChannelLeft,客户端据此把频道渲染为只读 left 预览。
-		ChannelLeft:         memberStatus == domain.ChannelMemberLeft,
+		ChannelLeft:            memberStatus == domain.ChannelMemberLeft,
-		FolderID:            dialog.FolderID,
+		FolderID:               dialog.FolderID,
-		TopMessage:          dialog.TopMessageID,
+		TopMessage:             dialog.TopMessageID,
-		TopMessageDate:      dialog.TopMessageDate,
+		TopMessageDate:         dialog.TopMessageDate,
-		ReadInboxMaxID:      dialog.ReadInboxMaxID,
+		HistoryClearAnchorID:   dialog.HistoryClearAnchorID,
-		ReadOutboxMaxID:     dialog.ReadOutboxMaxID,
+		HistoryClearAnchorDate: dialog.HistoryClearAnchorDate,
-		UnreadCount:         dialog.UnreadCount,
+		ReadInboxMaxID:         dialog.ReadInboxMaxID,
-		UnreadMentions:      dialog.UnreadMentions,
+		ReadOutboxMaxID:        dialog.ReadOutboxMaxID,
-		UnreadReactions:     dialog.UnreadReactions,
+		UnreadCount:            dialog.UnreadCount,
-		Pinned:              dialog.Pinned,
+		UnreadMentions:         dialog.UnreadMentions,
-		PinnedOrder:         dialog.PinnedOrder,
+		UnreadReactions:        dialog.UnreadReactions,
-		UnreadMark:          dialog.UnreadMark,
+		Pinned:                 dialog.Pinned,
-		ViewForumAsMessages: dialog.ViewForumAsMessages,
+		PinnedOrder:            dialog.PinnedOrder,
-		HasScheduled:        dialog.HasScheduled,
+		UnreadMark:             dialog.UnreadMark,
-		Pts:                 channelPts,
+		ViewForumAsMessages:    dialog.ViewForumAsMessages,
+		HasScheduled:           dialog.HasScheduled,
+		Pts:                    channelPts,
 	}
 }
 
 func previewChannelDialog(userID int64, channel domain.Channel, member domain.ChannelMember) domain.ChannelDialog {
 	topMessageID := channel.TopMessageID
 	if topMessageID <= member.AvailableMinID {
-		topMessageID = 0
+		topMessageID = member.HistoryClearAnchorID
+		if topMessageID != member.AvailableMinID {
+			topMessageID = 0
+		}
+	}
+	topMessageDate := channel.Date
+	if topMessageID > 0 && topMessageID == member.HistoryClearAnchorID {
+		topMessageDate = member.HistoryClearAnchorDate
 	}
 	return domain.ChannelDialog{
-		UserID:          userID,
+		UserID:                 userID,
-		ChannelID:       channel.ID,
+		ChannelID:              channel.ID,
-		TopMessageID:    topMessageID,
+		TopMessageID:           topMessageID,
-		TopMessageDate:  channel.Date,
+		TopMessageDate:         topMessageDate,
-		ReadInboxMaxID:  maxInt(channel.TopMessageID, member.ReadInboxMaxID),
+		HistoryClearAnchorID:   member.HistoryClearAnchorID,
-		ReadOutboxMaxID: maxInt(channel.TopMessageID, member.ReadOutboxMaxID),
+		HistoryClearAnchorDate: member.HistoryClearAnchorDate,
+		ReadInboxMaxID:         maxInt(channel.TopMessageID, member.ReadInboxMaxID),
+		ReadOutboxMaxID:        maxInt(channel.TopMessageID, member.ReadOutboxMaxID),
 	}
 }
 

internal/store/memory/channel_helpers.go

@@ -337,9 +337,19 @@ func (s *ChannelStore) ListDirtyActiveChannelsForUser(_ context.Context, userID
 		if !ok || member.Status != domain.ChannelMemberActive {
 			continue
 		}
+		item := domain.DirtyChannel{ChannelID: channelID, Pts: channel.Pts}
 		checkpoint := s.channelUpdateCheckpointLocked(channelID, channel)
 		if checkpoint.LatestEventDate > sinceDate {
-			out = append(out, domain.DirtyChannel{ChannelID: channelID, Pts: channel.Pts})
+			item.ChannelUpdatesDirty = true
+		}
+		if clearDate := s.historyClearDates[channelID][userID]; clearDate >= sinceDate &&
+			member.HistoryClearAnchorID > 0 &&
+			member.HistoryClearAnchorID == member.AvailableMinID {
+			item.AvailableMinID = member.AvailableMinID
+			item.HistoryClearDate = clearDate
+		}
+		if item.ChannelUpdatesDirty || item.AvailableMinID > 0 {
+			out = append(out, item)
 		}
 	}
 	for channelID, channel := range s.channels {
@@ -356,7 +366,11 @@ func (s *ChannelStore) ListDirtyActiveChannelsForUser(_ context.Context, userID
 				}
 			}
 			if !found {
-				out = append(out, domain.DirtyChannel{ChannelID: channelID, Pts: channel.Pts})
+				out = append(out, domain.DirtyChannel{
+					ChannelID:           channelID,
+					Pts:                 channel.Pts,
+					ChannelUpdatesDirty: true,
+				})
 			}
 		}
 	}
@@ -453,12 +467,16 @@ func (s *ChannelStore) dialogForMemberLocked(userID int64, channel domain.Channe
 	dialog.UserID = userID
 	dialog.ChannelID = channel.ID
 	dialog.TopMessageID = s.visibleTopMessageIDForMemberLocked(channel, member)
+	dialog.HistoryClearAnchorID = member.HistoryClearAnchorID
+	dialog.HistoryClearAnchorDate = member.HistoryClearAnchorDate
 	// TopMessageDate 必须从可见 top 消息派生(不能继承空缓存的 0),否则会话排序/分页与预览
 	// dialog 的日期全错。与 postgres GetChannelDialogs 用 getChannelMessage 设 date 对齐。
 	dialog.TopMessageDate = 0
 	if dialog.TopMessageID > 0 {
-		if top, ok := s.findMessageLocked(channel.ID, dialog.TopMessageID); ok {
+		if top, ok := s.channelMessageForMemberLocked(userID, channel.ID, dialog.TopMessageID); ok {
 			dialog.TopMessageDate = top.Date
+		} else if dialog.TopMessageID == member.HistoryClearAnchorID {
+			dialog.TopMessageDate = member.HistoryClearAnchorDate
 		}
 	}
 	if member.ReadInboxMaxID > dialog.ReadInboxMaxID {

internal/store/memory/channel_members.go

@@ -1107,6 +1107,8 @@ func syntheticMonoforumAdminMember(mono domain.Channel, parentMember domain.Chan
 	}
 	member.AvailableMinID = 0
 	member.AvailableMinPts = 0
+	member.HistoryClearAnchorID = 0
+	member.HistoryClearAnchorDate = 0
 	member.ReadInboxMaxID = mono.TopMessageID
 	member.ReadOutboxMaxID = mono.TopMessageID
 	member.UnreadMark = false

internal/store/memory/channel_message_delete.go

@@ -72,6 +72,12 @@ func (s *ChannelStore) DeleteChannelHistory(_ context.Context, req domain.Delete
 	if err != nil {
 		return domain.DeleteChannelHistoryResult{}, err
 	}
+	if req.Date <= 0 {
+		req.Date = channel.Date
+		if req.Date <= 0 {
+			req.Date = 1
+		}
+	}
 	maxID := req.MaxID
 	if maxID <= 0 || maxID > channel.TopMessageID {
 		maxID = channel.TopMessageID
@@ -79,6 +85,22 @@ func (s *ChannelStore) DeleteChannelHistory(_ context.Context, req domain.Delete
 	member := s.members[req.ChannelID][req.UserID]
 	if !req.ForEveryone {
 		appliedMinID := maxInt(member.AvailableMinID, maxID)
+		changed := appliedMinID > member.AvailableMinID
+		if changed {
+			anchorDate := req.Date
+			if msg, ok := s.findMessageLocked(req.ChannelID, appliedMinID); ok && msg.Date > 0 {
+				anchorDate = msg.Date
+			}
+			if anchorDate <= 0 {
+				anchorDate = channel.Date
+			}
+			member.HistoryClearAnchorID = appliedMinID
+			member.HistoryClearAnchorDate = anchorDate
+			if s.historyClearDates[req.ChannelID] == nil {
+				s.historyClearDates[req.ChannelID] = make(map[int64]int)
+			}
+			s.historyClearDates[req.ChannelID][req.UserID] = req.Date
+		}
 		member.AvailableMinID = appliedMinID
 		member.ReadInboxMaxID = maxInt(member.ReadInboxMaxID, appliedMinID)
 		member.UnreadMark = false
@@ -92,7 +114,11 @@ func (s *ChannelStore) DeleteChannelHistory(_ context.Context, req domain.Delete
 			s.dialogs[req.UserID] = make(map[int64]domain.ChannelDialog)
 		}
 		s.dialogs[req.UserID][req.ChannelID] = s.dialogForUserLocked(req.UserID, channel)
-		return domain.DeleteChannelHistoryResult{Channel: channel, AvailableMinID: appliedMinID}, nil
+		return domain.DeleteChannelHistoryResult{
+			Channel:             channel,
+			AvailableMinID:      appliedMinID,
+			AvailableMinChanged: changed,
+		}, nil
 	}
 	if !canDeleteAnyChannelMessage(member) {
 		return domain.DeleteChannelHistoryResult{}, domain.ErrChannelAdminRequired

internal/store/memory/channel_message_history.go

@@ -25,8 +25,16 @@ func (s *ChannelStore) ListChannelHistory(_ context.Context, viewerUserID int64,
 	query := strings.ToLower(strings.TrimSpace(filter.Query))
 	matched := make([]domain.ChannelMessage, 0, len(items))
 	monoforumUserView := channel.Monoforum && !member.CanManageDirectMessages()
+	anchorID := 0
+	if filter.IncludeHistoryClearAnchor &&
+		member.HistoryClearAnchorID > 0 &&
+		member.HistoryClearAnchorID == member.AvailableMinID {
+		anchorID = member.HistoryClearAnchorID
+	}
+	anchorSeen := false
 	for _, msg := range items {
-		if msg.Deleted {
+		isAnchor := anchorID > 0 && msg.ID == anchorID
+		if msg.Deleted && !isAnchor {
 			continue
 		}
 		if channel.Monoforum {
@@ -37,9 +45,18 @@ func (s *ChannelStore) ListChannelHistory(_ context.Context, viewerUserID int64,
 				continue
 			}
 		}
-		if msg.ID <= member.AvailableMinID {
+		if msg.ID < member.AvailableMinID || (msg.ID == member.AvailableMinID && !isAnchor) {
 			continue
 		}
+		if isAnchor {
+			msg = domain.ProjectChannelHistoryClearMessage(
+				msg,
+				filter.ChannelID,
+				member.HistoryClearAnchorID,
+				member.HistoryClearAnchorDate,
+			)
+			anchorSeen = true
+		}
 		if filter.PinnedOnly && !msg.Pinned {
 			continue
 		}
@@ -66,6 +83,24 @@ func (s *ChannelStore) ListChannelHistory(_ context.Context, viewerUserID int64,
 		}
 		matched = append(matched, msg)
 	}
+	if anchorID > 0 && !anchorSeen {
+		msg := domain.ProjectChannelHistoryClearMessage(
+			domain.ChannelMessage{},
+			filter.ChannelID,
+			member.HistoryClearAnchorID,
+			member.HistoryClearAnchorDate,
+		)
+		if (filter.MinDate <= 0 || msg.Date > filter.MinDate) &&
+			(filter.MaxDate <= 0 || msg.Date < filter.MaxDate) &&
+			(filter.MaxID <= 0 || msg.ID <= filter.MaxID) &&
+			(filter.MinID <= 0 || msg.ID > filter.MinID) &&
+			!filter.PinnedOnly &&
+			!filter.MusicOnly &&
+			query == "" &&
+			filter.SenderUserID == 0 {
+			matched = append(matched, msg)
+		}
+	}
 	extraChannels := []domain.Channel(nil)
 	if channel.Monoforum && channel.LinkedMonoforumID != 0 {
 		if parent, ok := s.channels[channel.LinkedMonoforumID]; ok && !parent.Deleted {
@@ -179,6 +214,7 @@ func (s *ChannelStore) ListChannelHistory(_ context.Context, viewerUserID int64,
 	}
 	s.populateChannelMessageRepliesLocked(viewerUserID, filter.ChannelID, out)
 	s.populateChannelMessageReactionsLocked(viewerUserID, channel, out)
+	projectMemoryChannelHistoryClearMessages(channel.ID, member, out)
 	return domain.ChannelHistory{
 		Channel:  channel,
 		Self:     member,
@@ -318,17 +354,59 @@ func (s *ChannelStore) GetChannelMessages(_ context.Context, viewerUserID, chann
 		if _, ok := wanted[msg.ID]; !ok {
 			continue
 		}
+		if msg.ID == member.HistoryClearAnchorID &&
+			member.HistoryClearAnchorID == member.AvailableMinID {
+			messages = append(messages, domain.ProjectChannelHistoryClearMessage(
+				msg,
+				channelID,
+				member.HistoryClearAnchorID,
+				member.HistoryClearAnchorDate,
+			))
+			delete(wanted, msg.ID)
+			continue
+		}
 		if msg.Deleted || msg.ID <= member.AvailableMinID {
 			continue
 		}
 		messages = append(messages, cloneChannelMessage(msg))
+		delete(wanted, msg.ID)
+	}
+	if member.HistoryClearAnchorID > 0 &&
+		member.HistoryClearAnchorID == member.AvailableMinID {
+		if _, ok := wanted[member.HistoryClearAnchorID]; ok {
+			messages = append(messages, domain.ProjectChannelHistoryClearMessage(
+				domain.ChannelMessage{},
+				channelID,
+				member.HistoryClearAnchorID,
+				member.HistoryClearAnchorDate,
+			))
+		}
 	}
 	sort.Slice(messages, func(i, j int) bool { return messages[i].ID > messages[j].ID })
 	s.populateChannelMessageRepliesLocked(viewerUserID, channelID, messages)
 	s.populateChannelMessageReactionsLocked(viewerUserID, channel, messages)
+	projectMemoryChannelHistoryClearMessages(channelID, member, messages)
 	return domain.ChannelHistory{Channel: channel, Self: member, Messages: messages, Count: len(messages)}, nil
 }
 
+func projectMemoryChannelHistoryClearMessages(channelID int64, member domain.ChannelMember, messages []domain.ChannelMessage) {
+	if member.HistoryClearAnchorID <= 0 ||
+		member.HistoryClearAnchorID != member.AvailableMinID {
+		return
+	}
+	for i := range messages {
+		if messages[i].ID != member.HistoryClearAnchorID {
+			continue
+		}
+		messages[i] = domain.ProjectChannelHistoryClearMessage(
+			messages[i],
+			channelID,
+			member.HistoryClearAnchorID,
+			member.HistoryClearAnchorDate,
+		)
+	}
+}
+
 func (s *ChannelStore) ListStoryMessageForwards(_ context.Context, req domain.StoryMessageForwardListRequest) (domain.StoryMessageForwardList, error) {
 	if req.ViewerUserID == 0 || req.Owner.ID == 0 || req.StoryID <= 0 || req.StoryID > domain.MaxStoryID {
 		return domain.StoryMessageForwardList{}, domain.ErrStoryIDInvalid
@@ -631,9 +709,40 @@ func (s *ChannelStore) visibleTopMessageIDForMemberLocked(channel domain.Channel
 			return msg.ID
 		}
 	}
+	if member.HistoryClearAnchorID > 0 &&
+		member.HistoryClearAnchorID == member.AvailableMinID {
+		return member.HistoryClearAnchorID
+	}
 	return 0
 }
 
+func (s *ChannelStore) channelMessageForMemberLocked(userID, channelID int64, messageID int) (domain.ChannelMessage, bool) {
+	member, ok := s.members[channelID][userID]
+	if !ok {
+		msg, found := s.findMessageLocked(channelID, messageID)
+		if !found || msg.Deleted {
+			return domain.ChannelMessage{}, false
+		}
+		return cloneChannelMessage(msg), true
+	}
+	if member.HistoryClearAnchorID > 0 &&
+		member.HistoryClearAnchorID == member.AvailableMinID &&
+		messageID == member.HistoryClearAnchorID {
+		source, _ := s.findMessageLocked(channelID, messageID)
+		return domain.ProjectChannelHistoryClearMessage(
+			source,
+			channelID,
+			member.HistoryClearAnchorID,
+			member.HistoryClearAnchorDate,
+		), true
+	}
+	msg, ok := s.findMessageLocked(channelID, messageID)
+	if !ok || msg.Deleted || msg.ID <= member.AvailableMinID {
+		return domain.ChannelMessage{}, false
+	}
+	return cloneChannelMessage(msg), true
+}
+
 func (s *ChannelStore) topicHasVisibleMessagesLocked(channelID int64, topicID int) bool {
 	for _, msg := range s.messages[channelID] {
 		if msg.Deleted {

internal/store/memory/channel_store.go

@@ -73,14 +73,19 @@ type ChannelStore struct {
 	messages  map[int64][]domain.ChannelMessage
 	reactions map[int64]map[int]map[int64][]domain.ChannelMessagePeerReaction
 	// paidReactions 是 per-(channel,message,user) 付费 reaction 累计星数 + 匿名标志。
-	paidReactions          map[int64]map[int]map[int64]memoryPaidReaction
+	paidReactions map[int64]map[int]map[int64]memoryPaidReaction
-	top                    map[int64]map[string]domain.TopMessageReaction
+	top           map[int64]map[string]domain.TopMessageReaction
-	recent                 map[int64]map[string]domain.RecentMessageReaction
+	recent        map[int64]map[string]domain.RecentMessageReaction
-	mentions               map[int64]map[int64]map[int]memoryMention
+	mentions      map[int64]map[int64]map[int]memoryMention
-	msgViews               map[int64]map[int]int
+	msgViews      map[int64]map[int]int
-	msgViewers             map[int64]map[int]map[int64]struct{}
+	msgViewers    map[int64]map[int]map[int64]struct{}
-	events                 map[int64][]domain.ChannelUpdateEvent
+	events        map[int64][]domain.ChannelUpdateEvent
-	retention              map[int64]domain.ChannelUpdateRetentionCheckpoint
+	retention     map[int64]domain.ChannelUpdateRetentionCheckpoint
+	// historyClearDates is the no-PTS recovery timestamp for a future
+	// owner-local clear, keyed by channel then user. The member remains the
+	// absolute boundary authority; this map only makes account difference
+	// discovery bounded without scanning messages.
+	historyClearDates      map[int64]map[int64]int
 	adminLogs              map[int64][]domain.ChannelAdminLogEvent
 	invites                map[string]domain.ChannelInvite
 	importers              map[int64]map[int64]domain.ChannelInviteImporter
@@ -137,6 +142,7 @@ func NewChannelStore() *ChannelStore {
 		msgViewers:             make(map[int64]map[int]map[int64]struct{}),
 		events:                 make(map[int64][]domain.ChannelUpdateEvent),
 		retention:              make(map[int64]domain.ChannelUpdateRetentionCheckpoint),
+		historyClearDates:      make(map[int64]map[int64]int),
 		adminLogs:              make(map[int64][]domain.ChannelAdminLogEvent),
 		invites:                make(map[string]domain.ChannelInvite),
 		importers:              make(map[int64]map[int64]domain.ChannelInviteImporter),

internal/store/memory/channel_test.go

@@ -873,6 +873,7 @@ func TestChannelDeleteHistoryLocalClearReturnsMonotonicAvailableMinID(t *testing
 		CreatorUserID: 1,
 		Title:         "monotonic local clear",
 		Megagroup:     true,
+		MemberUserIDs: []int64{2},
 		Date:          1_700_000_250,
 	})
 	if err != nil {
@@ -911,6 +912,20 @@ func TestChannelDeleteHistoryLocalClearReturnsMonotonicAvailableMinID(t *testing
 	if high.AvailableMinID != second.Message.ID {
 		t.Fatalf("high available_min_id = %d, want %d", high.AvailableMinID, second.Message.ID)
 	}
+	if !high.AvailableMinChanged {
+		t.Fatal("high clear did not report an advanced owner-local boundary")
+	}
+	dirtyAfterClear, err := store.ListDirtyActiveChannelsForUser(ctx, 1, 1_700_000_253, 0, 10)
+	if err != nil {
+		t.Fatalf("list dirty channels after owner-local clear: %v", err)
+	}
+	if len(dirtyAfterClear) != 1 ||
+		dirtyAfterClear[0].ChannelID != created.Channel.ID ||
+		dirtyAfterClear[0].AvailableMinID != second.Message.ID ||
+		dirtyAfterClear[0].HistoryClearDate != 1_700_000_253 ||
+		dirtyAfterClear[0].ChannelUpdatesDirty {
+		t.Fatalf("dirty owner-local clear = %+v, want only absolute boundary %d at date 1700000253", dirtyAfterClear, second.Message.ID)
+	}
 
 	stale, err := store.DeleteChannelHistory(ctx, domain.DeleteChannelHistoryRequest{
 		UserID:    1,
@@ -924,13 +939,38 @@ func TestChannelDeleteHistoryLocalClearReturnsMonotonicAvailableMinID(t *testing
 	if stale.AvailableMinID != second.Message.ID {
 		t.Fatalf("stale available_min_id = %d, want monotonic %d", stale.AvailableMinID, second.Message.ID)
 	}
+	if stale.AvailableMinChanged {
+		t.Fatal("stale clear unexpectedly replaced the owner-local anchor")
+	}
+	dirtyAfterStale, err := store.ListDirtyActiveChannelsForUser(ctx, 1, 1_700_000_254, 0, 10)
+	if err != nil {
+		t.Fatalf("list dirty channels after stale owner-local clear: %v", err)
+	}
+	if len(dirtyAfterStale) != 0 {
+		t.Fatalf("stale clear refreshed recovery timestamp: %+v", dirtyAfterStale)
+	}
 
 	history, err := store.ListChannelHistory(ctx, 1, domain.ChannelHistoryFilter{ChannelID: created.Channel.ID, Limit: 10})
 	if err != nil {
 		t.Fatalf("list history: %v", err)
 	}
 	if len(history.Messages) != 0 {
-		t.Fatalf("history after stale clear = %+v, want no visible messages", history.Messages)
+		t.Fatalf("unprojected history after stale clear = %+v, want no shared messages", history.Messages)
+	}
+	history, err = store.ListChannelHistory(ctx, 1, domain.ChannelHistoryFilter{
+		ChannelID:                 created.Channel.ID,
+		Limit:                     10,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("list projected history: %v", err)
+	}
+	if len(history.Messages) != 1 ||
+		history.Messages[0].ID != second.Message.ID ||
+		!domain.IsChannelHistoryClearMessage(history.Messages[0]) ||
+		history.Messages[0].Body != "" ||
+		history.Messages[0].Media != nil {
+		t.Fatalf("projected history after stale clear = %+v, want sanitized history-clear anchor %d", history.Messages, second.Message.ID)
 	}
 	dialogs, err := store.GetChannelDialogs(ctx, 1, []int64{created.Channel.ID})
 	if err != nil {
@@ -939,8 +979,140 @@ func TestChannelDeleteHistoryLocalClearReturnsMonotonicAvailableMinID(t *testing
 	if len(dialogs.Dialogs) != 1 {
 		t.Fatalf("dialogs = %+v, want one dialog", dialogs.Dialogs)
 	}
-	if dialogs.Dialogs[0].TopMessage != 0 || dialogs.Dialogs[0].ReadInboxMaxID != second.Message.ID || dialogs.Dialogs[0].UnreadCount != 0 {
+	if dialogs.Dialogs[0].TopMessage != second.Message.ID ||
-		t.Fatalf("dialog after stale clear = %+v, want top=0 read=%d unread=0", dialogs.Dialogs[0], second.Message.ID)
+		dialogs.Dialogs[0].ReadInboxMaxID != second.Message.ID ||
+		dialogs.Dialogs[0].UnreadCount != 0 ||
+		len(dialogs.Messages) != 1 ||
+		!domain.IsChannelHistoryClearMessage(dialogs.Messages[0]) {
+		t.Fatalf("dialog after stale clear = %+v messages=%+v, want anchored top=%d read=%d unread=0", dialogs.Dialogs[0], dialogs.Messages, second.Message.ID, second.Message.ID)
+	}
+	otherDialogs, err := store.GetChannelDialogs(ctx, 2, []int64{created.Channel.ID})
+	if err != nil {
+		t.Fatalf("get other member dialog: %v", err)
+	}
+	if len(otherDialogs.Dialogs) != 1 ||
+		otherDialogs.Dialogs[0].TopMessage != second.Message.ID ||
+		len(otherDialogs.Messages) != 1 ||
+		otherDialogs.Messages[0].Body != "second visible" ||
+		otherDialogs.Messages[0].Action != nil {
+		t.Fatalf("other member projection changed by owner clear: dialogs=%+v messages=%+v", otherDialogs.Dialogs, otherDialogs.Messages)
+	}
+}
+
+func TestChannelDeleteHistoryLocalClearKeepsMegagroupAndBroadcastDialogs(t *testing.T) {
+	for _, tc := range []struct {
+		name      string
+		megagroup bool
+		broadcast bool
+	}{
+		{name: "megagroup", megagroup: true},
+		{name: "broadcast", broadcast: true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx := context.Background()
+			store := NewChannelStore()
+			created, err := store.CreateChannel(ctx, domain.CreateChannelRequest{
+				CreatorUserID: 11,
+				Title:         tc.name + " local clear",
+				Megagroup:     tc.megagroup,
+				Broadcast:     tc.broadcast,
+				Date:          1_700_000_270,
+			})
+			if err != nil {
+				t.Fatalf("create channel: %v", err)
+			}
+			sent, err := store.SendChannelMessage(ctx, domain.SendChannelMessageRequest{
+				UserID:    11,
+				ChannelID: created.Channel.ID,
+				RandomID:  31_001,
+				Message:   "clear this",
+				Date:      1_700_000_271,
+			})
+			if err != nil {
+				t.Fatalf("send channel message: %v", err)
+			}
+			channelPts := sent.Channel.Pts
+			cleared, err := store.DeleteChannelHistory(ctx, domain.DeleteChannelHistoryRequest{
+				UserID:    11,
+				ChannelID: created.Channel.ID,
+				MaxID:     sent.Message.ID,
+				Date:      1_700_000_272,
+			})
+			if err != nil {
+				t.Fatalf("clear local history: %v", err)
+			}
+			if cleared.Channel.Pts != channelPts || cleared.Event.Pts != 0 {
+				t.Fatalf("local clear changed channel pts: before=%d result=%+v", channelPts, cleared)
+			}
+			dialogs, err := store.GetChannelDialogs(ctx, 11, []int64{created.Channel.ID})
+			if err != nil {
+				t.Fatalf("get dialogs after clear: %v", err)
+			}
+			if len(dialogs.Dialogs) != 1 ||
+				dialogs.Dialogs[0].TopMessage != sent.Message.ID ||
+				len(dialogs.Messages) != 1 ||
+				!domain.IsChannelHistoryClearMessage(dialogs.Messages[0]) {
+				t.Fatalf("dialog disappeared after %s clear: dialogs=%+v messages=%+v", tc.name, dialogs.Dialogs, dialogs.Messages)
+			}
+		})
+	}
+}
+
+func TestChannelPrehistoryBoundaryDoesNotCreateHistoryClearAnchor(t *testing.T) {
+	ctx := context.Background()
+	store := NewChannelStore()
+	created, err := store.CreateChannel(ctx, domain.CreateChannelRequest{
+		CreatorUserID: 21,
+		Title:         "hidden prehistory",
+		Megagroup:     true,
+		Date:          1_700_000_280,
+	})
+	if err != nil {
+		t.Fatalf("create channel: %v", err)
+	}
+	old, err := store.SendChannelMessage(ctx, domain.SendChannelMessageRequest{
+		UserID:    21,
+		ChannelID: created.Channel.ID,
+		RandomID:  32_001,
+		Message:   "prehistory",
+		Date:      1_700_000_281,
+	})
+	if err != nil {
+		t.Fatalf("send prehistory message: %v", err)
+	}
+	if _, err := store.SetPreHistoryHidden(ctx, 21, created.Channel.ID, true); err != nil {
+		t.Fatalf("hide prehistory: %v", err)
+	}
+	invited, err := store.InviteToChannel(ctx, created.Channel.ID, 21, []int64{22}, 1_700_000_282)
+	if err != nil {
+		t.Fatalf("invite member: %v", err)
+	}
+	if len(invited.Members) != 1 ||
+		invited.Members[0].AvailableMinID != old.Message.ID ||
+		invited.Members[0].HistoryClearAnchorID != 0 ||
+		invited.Members[0].HistoryClearAnchorDate != 0 {
+		t.Fatalf("invited member = %+v, want prehistory boundary without local-clear anchor", invited.Members)
+	}
+
+	history, err := store.ListChannelHistory(ctx, 22, domain.ChannelHistoryFilter{
+		ChannelID:                 created.Channel.ID,
+		Limit:                     10,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("list invited member history: %v", err)
+	}
+	for _, message := range history.Messages {
+		if message.ID == old.Message.ID || domain.IsChannelHistoryClearMessage(message) {
+			t.Fatalf("prehistory boundary leaked a local-clear marker: %+v", history.Messages)
+		}
+	}
+	byID, err := store.GetChannelMessages(ctx, 22, created.Channel.ID, []int{old.Message.ID})
+	if err != nil {
+		t.Fatalf("get prehistory message by id: %v", err)
+	}
+	if len(byID.Messages) != 0 {
+		t.Fatalf("prehistory message by id = %+v, want hidden without fabricated marker", byID.Messages)
 	}
 }
 

internal/store/postgres/channel_core.go

@@ -317,6 +317,7 @@ func (s *ChannelStore) GetChannels(ctx context.Context, viewerUserID int64, chan
 SELECT `+channelColumns+`,
        m.channel_id, m.user_id, m.inviter_user_id, m.role, m.status, m.joined_at, m.left_at,
        m.admin_rights::text, m.banned_rights::text, m.rank, m.available_min_id, m.available_min_pts,
+       m.history_clear_anchor_id, m.history_clear_anchor_date,
        m.read_inbox_max_id, m.read_outbox_max_id, m.unread_mark, m.slowmode_last_send_date
 FROM channels c
 JOIN channel_members m ON m.channel_id = c.id AND m.user_id = $1
@@ -529,7 +530,8 @@ func refreshChannelCountsTx(ctx context.Context, tx pgx.Tx, channel domain.Chann
 	var participants, admins, kicked, banned int
 	rows, err := tx.Query(ctx, `
 SELECT channel_id, user_id, inviter_user_id, role, status, joined_at, left_at, admin_rights::text, banned_rights::text,
-       rank, available_min_id, available_min_pts, read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
+       rank, available_min_id, available_min_pts, history_clear_anchor_id, history_clear_anchor_date,
+       read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
 FROM channel_members
 WHERE channel_id = $1`, channel.ID)
 	if err != nil {

internal/store/postgres/channel_dialogs.go

@@ -18,6 +18,26 @@ type channelDialogListItem struct {
 	defaultSendAs *domain.Peer
 }
 
+func channelDialogVisibleTopIDSQL() string {
+	return `CASE
+    WHEN c.top_message_id > m.available_min_id THEN c.top_message_id
+    WHEN m.history_clear_anchor_id > 0
+      AND m.history_clear_anchor_id = m.available_min_id
+      THEN m.history_clear_anchor_id
+    ELSE 0
+END`
+}
+
+func channelDialogVisibleTopDateSQL(globalTopDate, emptyFallback string) string {
+	return `CASE
+    WHEN c.top_message_id > m.available_min_id THEN ` + globalTopDate + `
+    WHEN m.history_clear_anchor_id > 0
+      AND m.history_clear_anchor_id = m.available_min_id
+      THEN m.history_clear_anchor_date
+    ELSE ` + emptyFallback + `
+END`
+}
+
 func (s *ChannelStore) ListChannelDialogs(ctx context.Context, viewerUserID int64, filter domain.DialogFilter) (domain.ChannelDialogList, error) {
 	if viewerUserID == 0 {
 		return domain.ChannelDialogList{}, nil
@@ -33,8 +53,8 @@ func (s *ChannelStore) ListChannelDialogs(ctx context.Context, viewerUserID int6
 	if len(channelIDs) == 0 {
 		return domain.ChannelDialogList{}, nil
 	}
-	visibleTopID := "CASE WHEN c.top_message_id > m.available_min_id THEN c.top_message_id ELSE 0 END"
+	visibleTopID := channelDialogVisibleTopIDSQL()
-	visibleTopDate := "CASE WHEN c.top_message_id > m.available_min_id THEN COALESCE(top_msg.message_date, d.top_message_date, c.date) ELSE 0 END"
+	visibleTopDate := channelDialogVisibleTopDateSQL("COALESCE(top_msg.message_date, d.top_message_date, c.date)", "0")
 	visibleReadInbox := "GREATEST(COALESCE(d.read_inbox_max_id, 0), m.read_inbox_max_id)"
 	visibleUnreadCount := channelDialogVisibleUnreadCountSQL(visibleReadInbox, visibleTopID)
 	args := []any{viewerUserID, channelIDs}
@@ -139,7 +159,9 @@ SELECT `+channelColumns+`,
        COALESCE(d.view_forum_as_messages, false),
        COALESCE(d.has_scheduled, false),
        d.default_send_as_peer_type,
-       d.default_send_as_peer_id
+       d.default_send_as_peer_id,
+       m.history_clear_anchor_id,
+       m.history_clear_anchor_date
 FROM channel_members m
 JOIN channels c ON c.id = m.channel_id AND c.id = ANY($2::bigint[]) AND NOT c.deleted
 LEFT JOIN channel_messages top_msg ON top_msg.channel_id = m.channel_id AND top_msg.channel_id = ANY($2::bigint[]) AND top_msg.id = c.top_message_id AND NOT top_msg.deleted
@@ -232,6 +254,7 @@ LIMIT `+limitArg, args...)
 	if err := s.populateChannelMessagesReactions(ctx, s.db, viewerUserID, out.Channels, out.Messages); err != nil {
 		return domain.ChannelDialogList{}, err
 	}
+	projectChannelDialogHistoryClearMessages(out.Dialogs, out.Messages)
 	return out, nil
 }
 
@@ -255,7 +278,9 @@ SELECT `+channelColumns+`,
        COALESCE(d.view_forum_as_messages, false),
        COALESCE(d.has_scheduled, false),
        d.default_send_as_peer_type,
-       d.default_send_as_peer_id
+       d.default_send_as_peer_id,
+       0,
+       0
 FROM user_channel_member_index i
 JOIN channel_members pm ON pm.user_id = i.user_id AND pm.channel_id = i.channel_id
 JOIN channels parent ON parent.id = i.channel_id AND parent.id = ANY($2::bigint[]) AND parent.broadcast AND parent.linked_monoforum_id <> 0 AND NOT parent.deleted
@@ -357,6 +382,20 @@ WHERE `+where.String(), args...)
 	if err := rows.Err(); err != nil {
 		return nil, fmt.Errorf("scan channel dialog top messages: %w", err)
 	}
+	for _, dialog := range dialogs {
+		if dialog.Peer.Type != domain.PeerTypeChannel ||
+			dialog.TopMessage <= 0 ||
+			dialog.TopMessage != dialog.HistoryClearAnchorID {
+			continue
+		}
+		key := channelMessageLookupKey{channelID: dialog.Peer.ID, id: dialog.TopMessage}
+		out[key] = domain.ProjectChannelHistoryClearMessage(
+			out[key],
+			dialog.Peer.ID,
+			dialog.HistoryClearAnchorID,
+			dialog.HistoryClearAnchorDate,
+		)
+	}
 	return out, nil
 }
 
@@ -413,6 +452,14 @@ func (s *ChannelStore) GetChannelDialogs(ctx context.Context, viewerUserID int64
 			}
 		}
 		msg, _ := s.getChannelMessage(ctx, s.db, channelID, dialog.TopMessageID)
+		if dialog.TopMessageID > 0 && dialog.TopMessageID == dialog.HistoryClearAnchorID {
+			msg = domain.ProjectChannelHistoryClearMessage(
+				msg,
+				channelID,
+				dialog.HistoryClearAnchorID,
+				dialog.HistoryClearAnchorDate,
+			)
+		}
 		if msg.ID != 0 {
 			dialog.TopMessageDate = msg.Date
 			out.Messages = append(out.Messages, msg)
@@ -425,9 +472,34 @@ func (s *ChannelStore) GetChannelDialogs(ctx context.Context, viewerUserID int64
 	if err := s.populateChannelMessagesReactions(ctx, s.db, viewerUserID, out.Channels, out.Messages); err != nil {
 		return domain.ChannelDialogList{}, err
 	}
+	projectChannelDialogHistoryClearMessages(out.Dialogs, out.Messages)
 	return out, nil
 }
 
+func projectChannelDialogHistoryClearMessages(dialogs []domain.Dialog, messages []domain.ChannelMessage) {
+	anchors := make(map[channelMessageLookupKey]domain.Dialog)
+	for _, dialog := range dialogs {
+		if dialog.Peer.Type != domain.PeerTypeChannel ||
+			dialog.TopMessage <= 0 ||
+			dialog.TopMessage != dialog.HistoryClearAnchorID {
+			continue
+		}
+		anchors[channelMessageLookupKey{channelID: dialog.Peer.ID, id: dialog.TopMessage}] = dialog
+	}
+	for i := range messages {
+		dialog, ok := anchors[channelMessageLookupKey{channelID: messages[i].ChannelID, id: messages[i].ID}]
+		if !ok {
+			continue
+		}
+		messages[i] = domain.ProjectChannelHistoryClearMessage(
+			messages[i],
+			dialog.Peer.ID,
+			dialog.HistoryClearAnchorID,
+			dialog.HistoryClearAnchorDate,
+		)
+	}
+}
+
 func (s *ChannelStore) ListCommonChannels(ctx context.Context, req domain.CommonChannelsRequest) (domain.CommonChannelsResult, error) {
 	if req.UserID == 0 || req.TargetUserID == 0 || req.UserID == req.TargetUserID || req.MaxID < 0 {
 		return domain.CommonChannelsResult{}, domain.ErrChannelInvalid
@@ -553,6 +625,7 @@ func (s *ChannelStore) leftChannelsByIDs(ctx context.Context, userID int64, ids
 	rows, err := s.db.Query(ctx, `
 SELECT channel_id, user_id, inviter_user_id, role, status, joined_at, left_at,
        admin_rights::text, banned_rights::text, rank, available_min_id, available_min_pts,
+       history_clear_anchor_id, history_clear_anchor_date,
        read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
 FROM channel_members
 WHERE user_id = $1
@@ -603,8 +676,8 @@ func (s *ChannelStore) ListInactiveChannels(ctx context.Context, userID int64, l
 	if len(channelIDs) == 0 {
 		return domain.ChannelDialogList{}, nil
 	}
-	visibleTopID := "CASE WHEN c.top_message_id > m.available_min_id THEN c.top_message_id ELSE 0 END"
+	visibleTopID := channelDialogVisibleTopIDSQL()
-	visibleTopDate := "CASE WHEN c.top_message_id > m.available_min_id THEN COALESCE(top_msg.message_date, d.top_message_date, c.date) ELSE GREATEST(c.date, m.joined_at) END"
+	visibleTopDate := channelDialogVisibleTopDateSQL("COALESCE(top_msg.message_date, d.top_message_date, c.date)", "GREATEST(c.date, m.joined_at)")
 	visibleReadInbox := "GREATEST(COALESCE(d.read_inbox_max_id, 0), m.read_inbox_max_id)"
 	visibleUnreadCount := channelDialogVisibleUnreadCountSQL(visibleReadInbox, visibleTopID)
 	rows, err := s.db.Query(ctx, `
@@ -619,7 +692,9 @@ SELECT `+channelColumns+`,
        COALESCE(d.view_forum_as_messages, false),
        COALESCE(d.has_scheduled, false),
        d.default_send_as_peer_type,
-       d.default_send_as_peer_id
+       d.default_send_as_peer_id,
+       m.history_clear_anchor_id,
+       m.history_clear_anchor_date
 FROM channel_members m
 JOIN channels c ON c.id = m.channel_id AND c.id = ANY($2::bigint[]) AND NOT c.deleted
 LEFT JOIN channel_messages top_msg ON top_msg.channel_id = m.channel_id AND top_msg.channel_id = ANY($2::bigint[]) AND top_msg.id = c.top_message_id AND NOT top_msg.deleted
@@ -856,6 +931,7 @@ func (s *ChannelStore) EditChannelPeerFolders(ctx context.Context, userID int64,
 	// 归档必须 ensure-INSERT：从未读过/置顶过的频道还没有 dialog 行，
 	// 只 UPDATE 会让归档静默丢失；新行同时带上 member 真实水位，
 	// 避免 0 水位缓存行遮蔽未读/已读状态。
+	visibleTopID := channelDialogVisibleTopIDSQL()
 	if _, err := s.db.Exec(ctx, `
 WITH requested AS (
     SELECT ($2::text[])[i] AS peer_type, ($3::bigint[])[i] AS channel_id, ($4::int[])[i] AS folder_id
@@ -870,7 +946,7 @@ deduped AS (
 )
 INSERT INTO channel_dialogs (user_id, channel_id, folder_id, top_message_id, read_inbox_max_id, read_outbox_max_id, unread_count, updated_at)
 SELECT $1, m.channel_id, deduped.folder_id,
-       CASE WHEN c.top_message_id > m.available_min_id THEN c.top_message_id ELSE 0 END,
+       `+visibleTopID+`,
        m.read_inbox_max_id, m.read_outbox_max_id,
        (
            SELECT COUNT(*)::int
@@ -904,7 +980,7 @@ func (s *ChannelStore) CountChannelArchiveUnread(ctx context.Context, userID int
 	// JOIN active member：退群残留的 channel_dialogs 行不计入归档徽章。
 	// unread 读时动态派生（H4a）：不再消费 channel_dialogs.unread_count 缓存列；归档集合
 	// 有界（需显式归档建行），每行动态 COUNT 已被 cap 钳制。
-	visibleTopID := "CASE WHEN c.top_message_id > m.available_min_id THEN c.top_message_id ELSE 0 END"
+	visibleTopID := channelDialogVisibleTopIDSQL()
 	visibleReadInbox := "GREATEST(COALESCE(d.read_inbox_max_id, 0), m.read_inbox_max_id)"
 	if err := s.db.QueryRow(ctx, `
 SELECT
@@ -937,7 +1013,7 @@ func (s *ChannelStore) getChannelDialogUncached(ctx context.Context, db sqlcgen.
 	dialog := domain.ChannelDialog{UserID: userID, ChannelID: channel.ID, TopMessageID: channel.TopMessageID}
 	var defaultSendAsType sql.NullString
 	var defaultSendAsID sql.NullInt64
-	visibleTopID := "CASE WHEN c.top_message_id > m.available_min_id THEN c.top_message_id ELSE 0 END"
+	visibleTopID := channelDialogVisibleTopIDSQL()
 	visibleReadInbox := "GREATEST(COALESCE(d.read_inbox_max_id, 0), m.read_inbox_max_id)"
 	visibleUnreadCount := channelDialogVisibleUnreadCountSQL(visibleReadInbox, visibleTopID)
 	// 单频道 TopMessageDate 用 LEFT JOIN top_msg 直接取,替代此前对每个频道再单查一次
@@ -946,7 +1022,10 @@ func (s *ChannelStore) getChannelDialogUncached(ctx context.Context, db sqlcgen.
 	// message_date(不过滤 deleted,与原 getChannelMessage 一致),否则回退
 	// COALESCE(d.top_message_date, c.date)。注意:与批量版 getChannelDialogs 的隐藏态
 	// (ELSE 0)刻意保持各自既有差异,本改动只去往返、不改单频道输出。
-	visibleTopDate := "CASE WHEN c.top_message_id > m.available_min_id AND top_msg.id IS NOT NULL THEN top_msg.message_date ELSE COALESCE(d.top_message_date, c.date) END"
+	visibleTopDate := channelDialogVisibleTopDateSQL(
+		"CASE WHEN top_msg.id IS NOT NULL THEN top_msg.message_date ELSE COALESCE(d.top_message_date, c.date) END",
+		"COALESCE(d.top_message_date, c.date)",
+	)
 	err := db.QueryRow(ctx, `
 SELECT `+visibleTopID+`,
        `+visibleTopDate+`,
@@ -962,7 +1041,9 @@ SELECT `+visibleTopID+`,
        COALESCE(d.view_forum_as_messages, false),
        COALESCE(d.has_scheduled, false),
        d.default_send_as_peer_type,
-       d.default_send_as_peer_id
+       d.default_send_as_peer_id,
+       m.history_clear_anchor_id,
+       m.history_clear_anchor_date
 FROM channels c
 JOIN channel_members m ON m.channel_id = c.id AND m.user_id = $1
 LEFT JOIN channel_messages top_msg ON top_msg.channel_id = c.id AND top_msg.id = c.top_message_id
@@ -983,6 +1064,8 @@ WHERE c.id = $2`, userID, channel.ID).Scan(
 		&dialog.HasScheduled,
 		&defaultSendAsType,
 		&defaultSendAsID,
+		&dialog.HistoryClearAnchorID,
+		&dialog.HistoryClearAnchorDate,
 	)
 	if err != nil && !errors.Is(err, pgx.ErrNoRows) {
 		return domain.ChannelDialog{}, fmt.Errorf("get channel dialog: %w", err)
@@ -1037,8 +1120,8 @@ func (s *ChannelStore) getChannelDialogsUncached(ctx context.Context, db sqlcgen
 	if userID == 0 || len(channelIDs) == 0 {
 		return nil, nil
 	}
-	visibleTopID := "CASE WHEN c.top_message_id > m.available_min_id THEN c.top_message_id ELSE 0 END"
+	visibleTopID := channelDialogVisibleTopIDSQL()
-	visibleTopDate := "CASE WHEN c.top_message_id > m.available_min_id THEN COALESCE(top_msg.message_date, d.top_message_date, c.date) ELSE 0 END"
+	visibleTopDate := channelDialogVisibleTopDateSQL("COALESCE(top_msg.message_date, d.top_message_date, c.date)", "0")
 	visibleReadInbox := "GREATEST(COALESCE(d.read_inbox_max_id, 0), m.read_inbox_max_id)"
 	visibleUnreadCount := channelDialogVisibleUnreadCountSQL(visibleReadInbox, visibleTopID)
 	rows, err := db.Query(ctx, `
@@ -1057,7 +1140,9 @@ SELECT c.id,
        COALESCE(d.view_forum_as_messages, false),
        COALESCE(d.has_scheduled, false),
        d.default_send_as_peer_type,
-       d.default_send_as_peer_id
+       d.default_send_as_peer_id,
+       m.history_clear_anchor_id,
+       m.history_clear_anchor_date
 FROM channels c
 JOIN channel_members m ON m.channel_id = c.id AND m.user_id = $1
 LEFT JOIN channel_messages top_msg ON top_msg.channel_id = c.id AND top_msg.id = c.top_message_id AND NOT top_msg.deleted
@@ -1089,6 +1174,8 @@ WHERE c.id = ANY($2::bigint[])`, userID, channelIDs)
 			&dialog.HasScheduled,
 			&defaultSendAsType,
 			&defaultSendAsID,
+			&dialog.HistoryClearAnchorID,
+			&dialog.HistoryClearAnchorDate,
 		); err != nil {
 			return nil, err
 		}
@@ -1197,6 +1284,7 @@ func scanChannelDialogRow(row rowScanner, userID int64) (domain.Channel, domain.
 	var rights, reactionPolicy string
 	var wallpaper *string
 	var topID, topDate, folderID, readInbox, readOutbox, unreadCount, pinnedOrder, unreadMentions, unreadReactions int
+	var historyClearAnchorID, historyClearAnchorDate int
 	var pinned, unreadMark, viewForumAsMessages, hasScheduled bool
 	var defaultSendAsType sql.NullString
 	var defaultSendAsID sql.NullInt64
@@ -1204,27 +1292,30 @@ func scanChannelDialogRow(row rowScanner, userID int64) (domain.Channel, domain.
 		&topID, &topDate,
 		&folderID, &readInbox, &readOutbox, &unreadCount, &pinned, &pinnedOrder, &unreadMark, &unreadMentions, &unreadReactions, &viewForumAsMessages, &hasScheduled,
 		&defaultSendAsType, &defaultSendAsID,
+		&historyClearAnchorID, &historyClearAnchorDate,
 	)
 	if err := row.Scan(dest...); err != nil {
 		return domain.Channel{}, domain.Dialog{}, nil, err
 	}
 	finishChannelScan(&ch, rights, reactionPolicy, wallpaper)
 	dialog := domain.Dialog{
-		Peer:                domain.Peer{Type: domain.PeerTypeChannel, ID: ch.ID},
+		Peer:                   domain.Peer{Type: domain.PeerTypeChannel, ID: ch.ID},
-		FolderID:            folderID,
+		FolderID:               folderID,
-		TopMessage:          topID,
+		TopMessage:             topID,
-		TopMessageDate:      topDate,
+		TopMessageDate:         topDate,
-		ReadInboxMaxID:      readInbox,
+		HistoryClearAnchorID:   historyClearAnchorID,
-		ReadOutboxMaxID:     readOutbox,
+		HistoryClearAnchorDate: historyClearAnchorDate,
-		UnreadCount:         unreadCount,
+		ReadInboxMaxID:         readInbox,
-		UnreadMentions:      unreadMentions,
+		ReadOutboxMaxID:        readOutbox,
-		UnreadReactions:     unreadReactions,
+		UnreadCount:            unreadCount,
-		Pinned:              pinned,
+		UnreadMentions:         unreadMentions,
-		PinnedOrder:         pinnedOrder,
+		UnreadReactions:        unreadReactions,
-		UnreadMark:          unreadMark,
+		Pinned:                 pinned,
-		ViewForumAsMessages: viewForumAsMessages,
+		PinnedOrder:            pinnedOrder,
-		HasScheduled:        hasScheduled,
+		UnreadMark:             unreadMark,
-		Pts:                 ch.Pts,
+		ViewForumAsMessages:    viewForumAsMessages,
+		HasScheduled:           hasScheduled,
+		Pts:                    ch.Pts,
 	}
 	var defaultSendAs *domain.Peer
 	if defaultSendAsType.Valid && defaultSendAsID.Valid && defaultSendAsID.Int64 != 0 {
@@ -1236,41 +1327,45 @@ func scanChannelDialogRow(row rowScanner, userID int64) (domain.Channel, domain.
 
 func channelDialogToDialog(dialog domain.ChannelDialog, channelPts int) domain.Dialog {
 	return domain.Dialog{
-		Peer:                domain.Peer{Type: domain.PeerTypeChannel, ID: dialog.ChannelID},
+		Peer:                   domain.Peer{Type: domain.PeerTypeChannel, ID: dialog.ChannelID},
-		FolderID:            dialog.FolderID,
+		FolderID:               dialog.FolderID,
-		TopMessage:          dialog.TopMessageID,
+		TopMessage:             dialog.TopMessageID,
-		TopMessageDate:      dialog.TopMessageDate,
+		TopMessageDate:         dialog.TopMessageDate,
-		ReadInboxMaxID:      dialog.ReadInboxMaxID,
+		HistoryClearAnchorID:   dialog.HistoryClearAnchorID,
-		ReadOutboxMaxID:     dialog.ReadOutboxMaxID,
+		HistoryClearAnchorDate: dialog.HistoryClearAnchorDate,
-		UnreadCount:         dialog.UnreadCount,
+		ReadInboxMaxID:         dialog.ReadInboxMaxID,
-		UnreadMentions:      dialog.UnreadMentions,
+		ReadOutboxMaxID:        dialog.ReadOutboxMaxID,
-		UnreadReactions:     dialog.UnreadReactions,
+		UnreadCount:            dialog.UnreadCount,
-		Pinned:              dialog.Pinned,
+		UnreadMentions:         dialog.UnreadMentions,
-		PinnedOrder:         dialog.PinnedOrder,
+		UnreadReactions:        dialog.UnreadReactions,
-		UnreadMark:          dialog.UnreadMark,
+		Pinned:                 dialog.Pinned,
-		ViewForumAsMessages: dialog.ViewForumAsMessages,
+		PinnedOrder:            dialog.PinnedOrder,
-		HasScheduled:        dialog.HasScheduled,
+		UnreadMark:             dialog.UnreadMark,
-		Pts:                 channelPts,
+		ViewForumAsMessages:    dialog.ViewForumAsMessages,
+		HasScheduled:           dialog.HasScheduled,
+		Pts:                    channelPts,
 	}
 }
 
 func channelDialogFromDialog(userID int64, dialog domain.Dialog) domain.ChannelDialog {
 	return domain.ChannelDialog{
-		UserID:              userID,
+		UserID:                 userID,
-		ChannelID:           dialog.Peer.ID,
+		ChannelID:              dialog.Peer.ID,
-		FolderID:            dialog.FolderID,
+		FolderID:               dialog.FolderID,
-		TopMessageID:        dialog.TopMessage,
+		TopMessageID:           dialog.TopMessage,
-		TopMessageDate:      dialog.TopMessageDate,
+		TopMessageDate:         dialog.TopMessageDate,
-		ReadInboxMaxID:      dialog.ReadInboxMaxID,
+		HistoryClearAnchorID:   dialog.HistoryClearAnchorID,
-		ReadOutboxMaxID:     dialog.ReadOutboxMaxID,
+		HistoryClearAnchorDate: dialog.HistoryClearAnchorDate,
-		UnreadCount:         dialog.UnreadCount,
+		ReadInboxMaxID:         dialog.ReadInboxMaxID,
-		UnreadMentions:      dialog.UnreadMentions,
+		ReadOutboxMaxID:        dialog.ReadOutboxMaxID,
-		UnreadReactions:     dialog.UnreadReactions,
+		UnreadCount:            dialog.UnreadCount,
-		Pinned:              dialog.Pinned,
+		UnreadMentions:         dialog.UnreadMentions,
-		PinnedOrder:         dialog.PinnedOrder,
+		UnreadReactions:        dialog.UnreadReactions,
-		UnreadMark:          dialog.UnreadMark,
+		Pinned:                 dialog.Pinned,
-		ViewForumAsMessages: dialog.ViewForumAsMessages,
+		PinnedOrder:            dialog.PinnedOrder,
-		HasScheduled:        dialog.HasScheduled,
+		UnreadMark:             dialog.UnreadMark,
+		ViewForumAsMessages:    dialog.ViewForumAsMessages,
+		HasScheduled:           dialog.HasScheduled,
 	}
 }
 
@@ -1392,14 +1487,23 @@ func channelFolderPeerIDs(primary []domain.DialogFolderPeer, rest ...[]domain.Di
 func previewChannelDialog(userID int64, channel domain.Channel, member domain.ChannelMember) domain.ChannelDialog {
 	topMessageID := channel.TopMessageID
 	if topMessageID <= member.AvailableMinID {
-		topMessageID = 0
+		topMessageID = member.HistoryClearAnchorID
+		if topMessageID != member.AvailableMinID {
+			topMessageID = 0
+		}
+	}
+	topMessageDate := channel.Date
+	if topMessageID > 0 && topMessageID == member.HistoryClearAnchorID {
+		topMessageDate = member.HistoryClearAnchorDate
 	}
 	return domain.ChannelDialog{
-		UserID:          userID,
+		UserID:                 userID,
-		ChannelID:       channel.ID,
+		ChannelID:              channel.ID,
-		TopMessageID:    topMessageID,
+		TopMessageID:           topMessageID,
-		TopMessageDate:  channel.Date,
+		TopMessageDate:         topMessageDate,
-		ReadInboxMaxID:  maxInt(channel.TopMessageID, member.ReadInboxMaxID),
+		HistoryClearAnchorID:   member.HistoryClearAnchorID,
-		ReadOutboxMaxID: maxInt(channel.TopMessageID, member.ReadOutboxMaxID),
+		HistoryClearAnchorDate: member.HistoryClearAnchorDate,
+		ReadInboxMaxID:         maxInt(channel.TopMessageID, member.ReadInboxMaxID),
+		ReadOutboxMaxID:        maxInt(channel.TopMessageID, member.ReadOutboxMaxID),
 	}
 }

internal/store/postgres/channel_helpers.go

@@ -31,7 +31,10 @@ func (s *ChannelStore) SaveChannelDefaultSendAs(ctx context.Context, req domain.
 	}
 	topMessageID := channel.TopMessageID
 	if topMessageID <= member.AvailableMinID {
-		topMessageID = 0
+		topMessageID = member.HistoryClearAnchorID
+		if topMessageID != member.AvailableMinID {
+			topMessageID = 0
+		}
 	}
 	if _, err := s.db.Exec(ctx, `
 INSERT INTO channel_dialogs (
@@ -393,15 +396,59 @@ LIMIT $4`, userID, sinceDate, afterChannelID, limit)
 		return nil, fmt.Errorf("list dirty active channels for user: %w", err)
 	}
 	defer rows.Close()
-	out := make([]domain.DirtyChannel, 0, limit)
+	byChannelID := make(map[int64]domain.DirtyChannel, limit*2)
 	for rows.Next() {
 		var item domain.DirtyChannel
 		if err := rows.Scan(&item.ChannelID, &item.Pts); err != nil {
 			return nil, err
 		}
+		item.ChannelUpdatesDirty = true
+		byChannelID[item.ChannelID] = item
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	clearRows, err := s.db.Query(ctx, `
+SELECT i.channel_id, c.pts, i.available_min_id, i.history_clear_updated_at
+FROM user_channel_member_index i
+JOIN channels c ON c.id = i.channel_id AND NOT c.deleted
+WHERE i.user_id = $1
+  AND i.status = 'active'
+  AND NOT i.deleted
+  AND i.channel_id > $3
+  AND i.history_clear_anchor_id > 0
+  AND i.history_clear_anchor_id = i.available_min_id
+  AND i.history_clear_updated_at >= $2
+ORDER BY i.channel_id ASC
+LIMIT $4`, userID, sinceDate, afterChannelID, limit)
+	if err != nil {
+		return nil, fmt.Errorf("list owner-local channel history clears for user: %w", err)
+	}
+	defer clearRows.Close()
+	for clearRows.Next() {
+		var item domain.DirtyChannel
+		if err := clearRows.Scan(&item.ChannelID, &item.Pts, &item.AvailableMinID, &item.HistoryClearDate); err != nil {
+			return nil, err
+		}
+		if existing, ok := byChannelID[item.ChannelID]; ok {
+			item.ChannelUpdatesDirty = existing.ChannelUpdatesDirty
+		}
+		byChannelID[item.ChannelID] = item
+	}
+	if err := clearRows.Err(); err != nil {
+		return nil, err
+	}
+
+	out := make([]domain.DirtyChannel, 0, len(byChannelID))
+	for _, item := range byChannelID {
 		out = append(out, item)
 	}
-	return out, rows.Err()
+	sort.Slice(out, func(i, j int) bool { return out[i].ChannelID < out[j].ChannelID })
+	if len(out) > limit {
+		out = out[:limit]
+	}
+	return out, nil
 }
 
 type rowScanner interface {

internal/store/postgres/channel_member_helpers.go

@@ -189,6 +189,7 @@ func getChannelMemberByID(ctx context.Context, db sqlcgen.DBTX, channelID, userI
 	row := db.QueryRow(ctx, `
 SELECT channel_id, user_id, inviter_user_id, role, status, joined_at, left_at,
        admin_rights::text, banned_rights::text, rank, available_min_id, available_min_pts,
+       history_clear_anchor_id, history_clear_anchor_date,
        read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
 FROM channel_members
 WHERE channel_id = $1 AND user_id = $2`, channelID, userID)
@@ -214,8 +215,9 @@ func upsertChannelMemberTx(ctx context.Context, tx pgx.Tx, channel domain.Channe
 	if _, err := tx.Exec(ctx, `
 INSERT INTO channel_members (
     channel_id, user_id, inviter_user_id, role, status, joined_at, left_at, admin_rights, banned_rights,
-    rank, available_min_id, available_min_pts, read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
+    rank, available_min_id, available_min_pts, history_clear_anchor_id, history_clear_anchor_date,
-) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16)
+    read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
+) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18)
 ON CONFLICT (channel_id, user_id) DO UPDATE SET
     inviter_user_id = EXCLUDED.inviter_user_id,
     role = EXCLUDED.role,
@@ -231,7 +233,8 @@ ON CONFLICT (channel_id, user_id) DO UPDATE SET
     updated_at = now()`,
 		member.ChannelID, member.UserID, member.InviterUserID, string(member.Role), string(member.Status),
 		member.JoinedAt, member.LeftAt, adminRights, bannedRights, member.Rank, member.AvailableMinID,
-		member.AvailableMinPts, member.ReadInboxMaxID, member.ReadOutboxMaxID, member.UnreadMark, member.SlowmodeLastSendDate); err != nil {
+		member.AvailableMinPts, member.HistoryClearAnchorID, member.HistoryClearAnchorDate,
+		member.ReadInboxMaxID, member.ReadOutboxMaxID, member.UnreadMark, member.SlowmodeLastSendDate); err != nil {
 		return fmt.Errorf("upsert channel member: %w", err)
 	}
 	return upsertUserChannelMemberIndexTx(ctx, tx, channel, member)
@@ -316,7 +319,8 @@ func scanChannelWithMember(row rowScanner) (domain.Channel, domain.ChannelMember
 	dest := append(channelScanDest(&ch, &defaultRights, &reactionPolicy, &wallpaper),
 		&member.ChannelID, &member.UserID, &member.InviterUserID, &role, &status,
 		&member.JoinedAt, &member.LeftAt, &adminRights, &bannedRights, &member.Rank,
-		&member.AvailableMinID, &member.AvailableMinPts, &member.ReadInboxMaxID, &member.ReadOutboxMaxID, &member.UnreadMark, &member.SlowmodeLastSendDate,
+		&member.AvailableMinID, &member.AvailableMinPts, &member.HistoryClearAnchorID, &member.HistoryClearAnchorDate,
+		&member.ReadInboxMaxID, &member.ReadOutboxMaxID, &member.UnreadMark, &member.SlowmodeLastSendDate,
 	)
 	if err := row.Scan(dest...); err != nil {
 		return domain.Channel{}, domain.ChannelMember{}, err
@@ -351,7 +355,8 @@ func scanChannelMember(row rowScanner) (domain.ChannelMember, error) {
 	if err := row.Scan(
 		&member.ChannelID, &member.UserID, &member.InviterUserID, &role, &status,
 		&member.JoinedAt, &member.LeftAt, &adminRights, &bannedRights, &member.Rank,
-		&member.AvailableMinID, &member.AvailableMinPts, &member.ReadInboxMaxID, &member.ReadOutboxMaxID, &member.UnreadMark, &member.SlowmodeLastSendDate,
+		&member.AvailableMinID, &member.AvailableMinPts, &member.HistoryClearAnchorID, &member.HistoryClearAnchorDate,
+		&member.ReadInboxMaxID, &member.ReadOutboxMaxID, &member.UnreadMark, &member.SlowmodeLastSendDate,
 	); err != nil {
 		return domain.ChannelMember{}, err
 	}
@@ -370,7 +375,8 @@ func scanChannelMemberWithCount(row rowScanner) (domain.ChannelMember, int, erro
 	if err := row.Scan(
 		&member.ChannelID, &member.UserID, &member.InviterUserID, &role, &status,
 		&member.JoinedAt, &member.LeftAt, &adminRights, &bannedRights, &member.Rank,
-		&member.AvailableMinID, &member.AvailableMinPts, &member.ReadInboxMaxID, &member.ReadOutboxMaxID, &member.UnreadMark, &member.SlowmodeLastSendDate,
+		&member.AvailableMinID, &member.AvailableMinPts, &member.HistoryClearAnchorID, &member.HistoryClearAnchorDate,
+		&member.ReadInboxMaxID, &member.ReadOutboxMaxID, &member.UnreadMark, &member.SlowmodeLastSendDate,
 		&count,
 	); err != nil {
 		return domain.ChannelMember{}, 0, err
@@ -471,6 +477,8 @@ func syntheticMonoforumAdminMember(mono domain.Channel, parentMember domain.Chan
 	}
 	member.AvailableMinID = 0
 	member.AvailableMinPts = 0
+	member.HistoryClearAnchorID = 0
+	member.HistoryClearAnchorDate = 0
 	member.ReadInboxMaxID = mono.TopMessageID
 	member.ReadOutboxMaxID = mono.TopMessageID
 	member.UnreadMark = false

internal/store/postgres/channel_member_join.go

@@ -267,6 +267,7 @@ func (s *ChannelStore) futureCreatorAfterLeave(ctx context.Context, db sqlcgen.D
 	member, err := scanChannelMember(db.QueryRow(ctx, `
 SELECT channel_id, user_id, inviter_user_id, role, status, joined_at, left_at,
        admin_rights::text, banned_rights::text, rank, available_min_id, available_min_pts,
+       history_clear_anchor_id, history_clear_anchor_date,
        read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
 FROM channel_members
 WHERE channel_id = $1

internal/store/postgres/channel_member_list.go

@@ -128,7 +128,8 @@ func (s *ChannelStore) GetParticipants(ctx context.Context, viewerUserID, channe
 	}
 	rows, err := s.db.Query(ctx, `
 SELECT channel_id, user_id, inviter_user_id, role, status, joined_at, left_at, admin_rights::text, banned_rights::text,
-       rank, available_min_id, available_min_pts, read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
+       rank, available_min_id, available_min_pts, history_clear_anchor_id, history_clear_anchor_date,
+       read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
 `+from+`
 WHERE `+strings.Join(where, " AND ")+`
 ORDER BY CASE role WHEN 'creator' THEN 0 WHEN 'admin' THEN 1 ELSE 2 END, user_id
@@ -221,7 +222,8 @@ func (s *ChannelStore) ListActiveChannelMembers(ctx context.Context, viewerUserI
 	}
 	rows, err := s.db.Query(ctx, `
 SELECT channel_id, user_id, inviter_user_id, role, status, joined_at, left_at, admin_rights::text, banned_rights::text,
-       rank, available_min_id, available_min_pts, read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
+       rank, available_min_id, available_min_pts, history_clear_anchor_id, history_clear_anchor_date,
+       read_inbox_max_id, read_outbox_max_id, unread_mark, slowmode_last_send_date
 FROM channel_members
 WHERE channel_id = $1 AND status = 'active'
 ORDER BY user_id
@@ -264,6 +266,7 @@ func (s *ChannelStore) ListActiveChannelBotMembers(ctx context.Context, viewerUs
 	rows, err := s.db.Query(ctx, `
 SELECT m.channel_id, m.user_id, m.inviter_user_id, m.role, m.status, m.joined_at, m.left_at,
        m.admin_rights::text, m.banned_rights::text, m.rank, m.available_min_id, m.available_min_pts,
+       m.history_clear_anchor_id, m.history_clear_anchor_date,
        m.read_inbox_max_id, m.read_outbox_max_id, m.unread_mark, m.slowmode_last_send_date,
        COUNT(*) OVER()::int
 FROM bots b

internal/store/postgres/channel_message_delete.go

@@ -2,6 +2,7 @@ package postgres
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"github.com/jackc/pgx/v5"
 	"sort"
@@ -223,19 +224,68 @@ func (s *ChannelStore) DeleteChannelHistory(ctx context.Context, req domain.Dele
 	}
 	if !req.ForEveryone {
 		appliedMinID := maxInt(member.AvailableMinID, maxID)
+		changed := appliedMinID > member.AvailableMinID
+		anchorID := member.HistoryClearAnchorID
+		anchorDate := member.HistoryClearAnchorDate
+		if changed {
+			anchorID = appliedMinID
+			anchorDate = req.Date
+			var messageDate int
+			err := tx.QueryRow(ctx, `
+SELECT message_date
+FROM channel_messages
+WHERE channel_id = $1 AND id = $2`, req.ChannelID, appliedMinID).Scan(&messageDate)
+			switch {
+			case err == nil && messageDate > 0:
+				anchorDate = messageDate
+			case errors.Is(err, pgx.ErrNoRows):
+				// max_id may name an already-pruned/hole id. The owner-local
+				// marker is still a valid monotonic boundary; retain request
+				// time so its dialog projection remains loadable.
+			case err != nil:
+				return domain.DeleteChannelHistoryResult{}, fmt.Errorf("select channel clear anchor date: %w", err)
+			}
+			if anchorDate <= 0 {
+				anchorDate = channel.Date
+			}
+		}
 		topID, topDate, err := visibleChannelTopAfter(ctx, tx, req.ChannelID, appliedMinID, channel.Date)
 		if err != nil {
 			return domain.DeleteChannelHistoryResult{}, err
 		}
+		if topID == 0 && anchorID > 0 && anchorID == appliedMinID {
+			topID = anchorID
+			topDate = anchorDate
+		}
 		if _, err := tx.Exec(ctx, `
 UPDATE channel_members
 SET available_min_id = GREATEST(available_min_id, $3),
+    history_clear_anchor_id = CASE WHEN available_min_id < $3 THEN $3 ELSE history_clear_anchor_id END,
+    history_clear_anchor_date = CASE WHEN available_min_id < $3 THEN $4 ELSE history_clear_anchor_date END,
     read_inbox_max_id = GREATEST(read_inbox_max_id, $3),
     unread_mark = false,
     updated_at = now()
-WHERE channel_id = $1 AND user_id = $2`, req.ChannelID, req.UserID, appliedMinID); err != nil {
+WHERE channel_id = $1 AND user_id = $2`, req.ChannelID, req.UserID, appliedMinID, anchorDate); err != nil {
 			return domain.DeleteChannelHistoryResult{}, fmt.Errorf("update channel local clear member: %w", err)
 		}
+		if changed {
+			member.AvailableMinID = appliedMinID
+			member.HistoryClearAnchorID = anchorID
+			member.HistoryClearAnchorDate = anchorDate
+			if err := upsertUserChannelMemberIndexTx(ctx, tx, channel, member); err != nil {
+				return domain.DeleteChannelHistoryResult{}, err
+			}
+			if _, err := tx.Exec(ctx, `
+UPDATE user_channel_member_index
+SET available_min_id = $3,
+    history_clear_anchor_id = $3,
+    history_clear_updated_at = $4,
+    updated_at = now()
+WHERE user_id = $1 AND channel_id = $2`,
+				req.UserID, req.ChannelID, appliedMinID, req.Date); err != nil {
+				return domain.DeleteChannelHistoryResult{}, fmt.Errorf("update channel local clear recovery index: %w", err)
+			}
+		}
 		if err := deleteChannelUnreadMentionsUpToTx(ctx, tx, req.UserID, req.ChannelID, appliedMinID); err != nil {
 			return domain.DeleteChannelHistoryResult{}, err
 		}
@@ -259,7 +309,17 @@ ON CONFLICT (user_id, channel_id) DO UPDATE SET
 			return domain.DeleteChannelHistoryResult{}, fmt.Errorf("commit local clear channel history: %w", err)
 		}
 		committed = true
-		return domain.DeleteChannelHistoryResult{Channel: channel, AvailableMinID: appliedMinID}, nil
+		if s.memberCacheActive(s.db) {
+			s.memberCache.delete(req.ChannelID, req.UserID)
+		}
+		if s.dialogCacheActive(s.db) {
+			s.dialogCache.delete(req.UserID, req.ChannelID)
+		}
+		return domain.DeleteChannelHistoryResult{
+			Channel:             channel,
+			AvailableMinID:      appliedMinID,
+			AvailableMinChanged: changed,
+		}, nil
 	}
 	if !canDeleteAnyChannelMessage(member) {
 		return domain.DeleteChannelHistoryResult{}, domain.ErrChannelAdminRequired

internal/store/postgres/channel_message_history.go

@@ -79,6 +79,10 @@ AND EXISTS (
 		baseArgs = append(baseArgs, filter.MinID)
 		base += fmt.Sprintf(" AND id > $%d", len(baseArgs))
 	}
+	historyClearAnchor, hasHistoryClearAnchor, err := s.channelHistoryClearAnchor(ctx, channel, member, filter)
+	if err != nil {
+		return domain.ChannelHistory{}, err
+	}
 	out := domain.ChannelHistory{Channel: channel, Self: member, Channels: extraChannels}
 	needExactTotal := filter.NeedTotalCount || filter.CountOnly
 	exactTotal := 0
@@ -92,6 +96,9 @@ AND EXISTS (
 		).Scan(&exactTotal); err != nil {
 			return domain.ChannelHistory{}, fmt.Errorf("count channel history: %w", err)
 		}
+		if hasHistoryClearAnchor {
+			exactTotal++
+		}
 		out.Count = exactTotal
 	}
 	if filter.CountOnly {
@@ -134,6 +141,18 @@ AND EXISTS (
 		}
 		return "false"
 	}
+	anchorMatchesForward := func() bool {
+		if !hasHistoryClearAnchor {
+			return false
+		}
+		if filter.OffsetDate > 0 {
+			return historyClearAnchor.Date >= filter.OffsetDate
+		}
+		if filter.OffsetID > 0 {
+			return historyClearAnchor.ID > filter.OffsetID
+		}
+		return false
+	}
 	aroundOlderCond := func(args *[]any) string {
 		if filter.OffsetDate > 0 {
 			*args = append(*args, filter.OffsetDate)
@@ -145,6 +164,30 @@ AND EXISTS (
 		}
 		return "true"
 	}
+	anchorMatchesAroundOlder := func() bool {
+		if !hasHistoryClearAnchor {
+			return false
+		}
+		if filter.OffsetDate > 0 {
+			return historyClearAnchor.Date < filter.OffsetDate
+		}
+		if filter.OffsetID > 0 {
+			return historyClearAnchor.ID <= filter.OffsetID
+		}
+		return true
+	}
+	anchorMatchesBackward := func() bool {
+		if !hasHistoryClearAnchor {
+			return false
+		}
+		if filter.OffsetDate > 0 {
+			return historyClearAnchor.Date < filter.OffsetDate
+		}
+		if filter.OffsetID > 0 {
+			return historyClearAnchor.ID < filter.OffsetID
+		}
+		return true
+	}
 	switch {
 	case addOffset < 0 && addOffset+limit > 0:
 		// around：以锚点为中心，向更新取 -add_offset 条 + 向更旧（含锚点）取 limit+add_offset 条
@@ -157,6 +200,12 @@ AND EXISTS (
 		if err != nil {
 			return domain.ChannelHistory{}, err
 		}
+		if anchorMatchesForward() {
+			newer = append([]domain.ChannelMessage{historyClearAnchor}, newer...)
+			if len(newer) > fwdLimit {
+				newer = newer[:fwdLimit]
+			}
+		}
 		bwdArgs := append([]any{}, baseArgs...)
 		bwdWhere := aroundOlderCond(&bwdArgs)
 		bwdArgs = append(bwdArgs, bwdLimit+1)
@@ -164,6 +213,9 @@ AND EXISTS (
 		if err != nil {
 			return domain.ChannelHistory{}, err
 		}
+		if anchorMatchesAroundOlder() {
+			older = append(older, historyClearAnchor)
+		}
 		if len(older) > bwdLimit {
 			older = older[:bwdLimit]
 			hasMoreOlder = true
@@ -181,6 +233,9 @@ AND EXISTS (
 		if err != nil {
 			return domain.ChannelHistory{}, err
 		}
+		if anchorMatchesForward() {
+			newer = append([]domain.ChannelMessage{historyClearAnchor}, newer...)
+		}
 		if len(newer) > limit {
 			newer = newer[:limit]
 		}
@@ -198,18 +253,26 @@ AND EXISTS (
 			args = append(args, filter.OffsetID)
 			where += fmt.Sprintf(" AND id < $%d", len(args))
 		}
-		args = append(args, limit+1)
+		// Fetch the bounded add_offset window and slice it in memory. This keeps
+		// the shared-history branch on its ordered (channel_id,id) seek index;
+		// the owner-local anchor is one separate PK lookup and never adds an OR
+		// that would force BitmapOr + Sort for large channels.
+		args = append(args, addOffset+limit+1)
 		limIdx := len(args)
-		sql := "SELECT " + channelMessageColumns + " FROM channel_messages WHERE " + where + " ORDER BY id DESC"
+		sql := "SELECT " + channelMessageColumns + " FROM channel_messages WHERE " + where +
-		if addOffset > 0 {
+			fmt.Sprintf(" ORDER BY id DESC LIMIT $%d", limIdx)
-			args = append(args, addOffset)
-			sql += fmt.Sprintf(" OFFSET $%d", len(args))
-		}
-		sql += fmt.Sprintf(" LIMIT $%d", limIdx)
 		older, err := scanList(sql, args)
 		if err != nil {
 			return domain.ChannelHistory{}, err
 		}
+		if anchorMatchesBackward() {
+			older = append(older, historyClearAnchor)
+		}
+		if addOffset >= len(older) {
+			older = nil
+		} else if addOffset > 0 {
+			older = older[addOffset:]
+		}
 		if len(older) > limit {
 			older = older[:limit]
 			hasMoreOlder = true
@@ -228,9 +291,63 @@ AND EXISTS (
 	if err := s.populateChannelMessagesReactions(ctx, s.db, viewerUserID, []domain.Channel{channel}, out.Messages); err != nil {
 		return domain.ChannelHistory{}, err
 	}
+	if hasHistoryClearAnchor {
+		for i := range out.Messages {
+			if out.Messages[i].ID == historyClearAnchor.ID {
+				out.Messages[i] = domain.ProjectChannelHistoryClearMessage(
+					out.Messages[i],
+					channel.ID,
+					member.HistoryClearAnchorID,
+					member.HistoryClearAnchorDate,
+				)
+			}
+		}
+	}
 	return out, nil
 }
 
+func (s *ChannelStore) channelHistoryClearAnchor(
+	ctx context.Context,
+	channel domain.Channel,
+	member domain.ChannelMember,
+	filter domain.ChannelHistoryFilter,
+) (domain.ChannelMessage, bool, error) {
+	if !filter.IncludeHistoryClearAnchor ||
+		member.HistoryClearAnchorID <= 0 ||
+		member.HistoryClearAnchorID != member.AvailableMinID ||
+		filter.PinnedOnly ||
+		filter.MusicOnly ||
+		filter.Query != "" {
+		return domain.ChannelMessage{}, false, nil
+	}
+	source, err := s.getChannelMessage(ctx, s.db, channel.ID, member.HistoryClearAnchorID)
+	if err != nil && !errors.Is(err, domain.ErrMessageIDInvalid) {
+		return domain.ChannelMessage{}, false, fmt.Errorf("load channel history-clear anchor: %w", err)
+	}
+	anchor := domain.ProjectChannelHistoryClearMessage(
+		source,
+		channel.ID,
+		member.HistoryClearAnchorID,
+		member.HistoryClearAnchorDate,
+	)
+	if filter.SenderUserID != 0 && anchor.SenderUserID != filter.SenderUserID {
+		return domain.ChannelMessage{}, false, nil
+	}
+	if filter.MinDate > 0 && anchor.Date <= filter.MinDate {
+		return domain.ChannelMessage{}, false, nil
+	}
+	if filter.MaxDate > 0 && anchor.Date >= filter.MaxDate {
+		return domain.ChannelMessage{}, false, nil
+	}
+	if filter.MaxID > 0 && anchor.ID > filter.MaxID {
+		return domain.ChannelMessage{}, false, nil
+	}
+	if filter.MinID > 0 && anchor.ID <= filter.MinID {
+		return domain.ChannelMessage{}, false, nil
+	}
+	return anchor, true, nil
+}
+
 func (s *ChannelStore) SearchJoinedMessages(ctx context.Context, viewerUserID int64, req domain.ChannelGlobalSearchRequest) (domain.ChannelHistory, error) {
 	query := strings.TrimSpace(req.Query)
 	if viewerUserID == 0 || (query == "" && !req.MusicOnly) {
@@ -390,8 +507,15 @@ func (s *ChannelStore) getChannelMessagesForMember(ctx context.Context, viewerUs
 	// 执行不变。注意:这种"OR 哨兵"只对【非排序锚点】的残余过滤安全;ListChannelHistory
 	// 的方向/anchor 条件若同样哨兵化会让规划器无法用索引顺序做 LIMIT、退化为全表扫+排序
 	// (实测 0.06ms→23ms),故那里【刻意保留】动态 SQL。
-	args := []any{channel.ID, id32, member.AvailableMinID}
+	anchorID := 0
-	where := "channel_id = $1 AND id = ANY($2::int[]) AND NOT deleted AND ($3 <= 0 OR id > $3)"
+	if member.HistoryClearAnchorID > 0 && member.HistoryClearAnchorID == member.AvailableMinID {
+		anchorID = member.HistoryClearAnchorID
+	}
+	args := []any{channel.ID, id32, member.AvailableMinID, anchorID}
+	where := `channel_id = $1
+AND id = ANY($2::int[])
+AND (NOT deleted OR ($4 > 0 AND id = $4))
+AND (($3 <= 0 OR id > $3) OR ($4 > 0 AND id = $4))`
 	rows, err := s.db.Query(ctx, `
 SELECT `+channelMessageColumns+`
 FROM channel_messages
@@ -419,6 +543,36 @@ ORDER BY id DESC`, args...)
 	if err := s.populateChannelMessagesReactions(ctx, s.db, viewerUserID, []domain.Channel{channel}, out.Messages); err != nil {
 		return domain.ChannelHistory{}, err
 	}
+	if anchorID > 0 {
+		anchorFound := false
+		for i := range out.Messages {
+			if out.Messages[i].ID != anchorID {
+				continue
+			}
+			out.Messages[i] = domain.ProjectChannelHistoryClearMessage(
+				out.Messages[i],
+				channel.ID,
+				member.HistoryClearAnchorID,
+				member.HistoryClearAnchorDate,
+			)
+			anchorFound = true
+		}
+		if !anchorFound {
+			for _, id := range ids {
+				if id != anchorID {
+					continue
+				}
+				out.Messages = append(out.Messages, domain.ProjectChannelHistoryClearMessage(
+					domain.ChannelMessage{},
+					channel.ID,
+					member.HistoryClearAnchorID,
+					member.HistoryClearAnchorDate,
+				))
+				out.Count = len(out.Messages)
+				break
+			}
+		}
+	}
 	return out, nil
 }
 

internal/store/postgres/channel_message_integration_test.go

@@ -189,6 +189,17 @@ WHERE channel_id = $1 AND user_id = $2`, channelID, owner.ID).Scan(&ownerMemberR
 		t.Fatalf("read participants = %+v, want friend read date", readers.Participants)
 	}
 
+	var channelPtsBeforeClear, channelEventsBeforeClear int
+	if err := pool.QueryRow(ctx, `
+SELECT c.pts, (
+    SELECT count(*)::int
+    FROM channel_update_events e
+    WHERE e.channel_id = c.id
+)
+FROM channels c
+WHERE c.id = $1`, channelID).Scan(&channelPtsBeforeClear, &channelEventsBeforeClear); err != nil {
+		t.Fatalf("query channel state before local clear: %v", err)
+	}
 	cleared, err := channels.DeleteChannelHistory(ctx, domain.DeleteChannelHistoryRequest{
 		UserID:    friend.ID,
 		ChannelID: channelID,
@@ -201,6 +212,70 @@ WHERE channel_id = $1 AND user_id = $2`, channelID, owner.ID).Scan(&ownerMemberR
 	if cleared.AvailableMinID != sent.Message.ID {
 		t.Fatalf("local clear available_min_id = %d, want %d", cleared.AvailableMinID, sent.Message.ID)
 	}
+	if !cleared.AvailableMinChanged {
+		t.Fatal("local clear did not report an advanced owner-local boundary")
+	}
+	var channelPtsAfterClear, channelEventsAfterClear int
+	if err := pool.QueryRow(ctx, `
+SELECT c.pts, (
+    SELECT count(*)::int
+    FROM channel_update_events e
+    WHERE e.channel_id = c.id
+)
+FROM channels c
+WHERE c.id = $1`, channelID).Scan(&channelPtsAfterClear, &channelEventsAfterClear); err != nil {
+		t.Fatalf("query channel state after local clear: %v", err)
+	}
+	if channelPtsAfterClear != channelPtsBeforeClear || channelEventsAfterClear != channelEventsBeforeClear {
+		t.Fatalf("local clear changed channel sequence: pts %d->%d events %d->%d",
+			channelPtsBeforeClear, channelPtsAfterClear, channelEventsBeforeClear, channelEventsAfterClear)
+	}
+	var recoveryMinID, recoveryAnchorID, recoveryDate int
+	if err := pool.QueryRow(ctx, `
+SELECT available_min_id, history_clear_anchor_id, history_clear_updated_at
+FROM user_channel_member_index
+WHERE user_id = $1 AND channel_id = $2`, friend.ID, channelID).Scan(
+		&recoveryMinID, &recoveryAnchorID, &recoveryDate,
+	); err != nil {
+		t.Fatalf("query owner-local clear recovery index: %v", err)
+	}
+	if recoveryMinID != sent.Message.ID || recoveryAnchorID != sent.Message.ID || recoveryDate != 1700000302 {
+		t.Fatalf("recovery index = min %d anchor %d date %d, want %d/%d/1700000302",
+			recoveryMinID, recoveryAnchorID, recoveryDate, sent.Message.ID, sent.Message.ID)
+	}
+	dirtyAfterClear, err := channels.ListDirtyActiveChannelsForUser(ctx, friend.ID, 1700000302, 0, 10)
+	if err != nil {
+		t.Fatalf("list dirty channels after local clear: %v", err)
+	}
+	if len(dirtyAfterClear) != 1 ||
+		dirtyAfterClear[0].ChannelID != channelID ||
+		dirtyAfterClear[0].AvailableMinID != sent.Message.ID ||
+		dirtyAfterClear[0].HistoryClearDate != 1700000302 {
+		t.Fatalf("dirty channel recovery = %+v, want channel %d boundary %d", dirtyAfterClear, channelID, sent.Message.ID)
+	}
+	planTx, err := pool.Begin(ctx)
+	if err != nil {
+		t.Fatalf("begin history-clear recovery plan transaction: %v", err)
+	}
+	defer func() { _ = planTx.Rollback(ctx) }()
+	if _, err := planTx.Exec(ctx, "SET LOCAL enable_seqscan = off"); err != nil {
+		t.Fatalf("disable seqscan for history-clear recovery plan: %v", err)
+	}
+	clearPlan := explainText(t, ctx, planTx, `
+SELECT i.channel_id, c.pts, i.available_min_id, i.history_clear_updated_at
+FROM user_channel_member_index i
+JOIN channels c ON c.id = i.channel_id AND NOT c.deleted
+WHERE i.user_id = $1
+  AND i.status = 'active'
+  AND NOT i.deleted
+  AND i.channel_id > $3
+  AND i.history_clear_anchor_id > 0
+  AND i.history_clear_anchor_id = i.available_min_id
+  AND i.history_clear_updated_at >= $2
+ORDER BY i.channel_id ASC
+LIMIT $4`, friend.ID, 1700000302, int64(0), 10)
+	requirePlanContains(t, clearPlan, "user_channel_member_index_history_clear_idx")
+	_ = planTx.Rollback(ctx)
 	staleClear, err := channels.DeleteChannelHistory(ctx, domain.DeleteChannelHistoryRequest{
 		UserID:    friend.ID,
 		ChannelID: channelID,
@@ -213,12 +288,60 @@ WHERE channel_id = $1 AND user_id = $2`, channelID, owner.ID).Scan(&ownerMemberR
 	if staleClear.AvailableMinID != sent.Message.ID {
 		t.Fatalf("stale local clear available_min_id = %d, want monotonic %d", staleClear.AvailableMinID, sent.Message.ID)
 	}
+	if staleClear.AvailableMinChanged {
+		t.Fatal("stale local clear unexpectedly replaced the owner-local anchor")
+	}
+	if err := pool.QueryRow(ctx, `
+SELECT history_clear_updated_at
+FROM user_channel_member_index
+WHERE user_id = $1 AND channel_id = $2`, friend.ID, channelID).Scan(&recoveryDate); err != nil {
+		t.Fatalf("query recovery timestamp after stale clear: %v", err)
+	}
+	if recoveryDate != 1700000302 {
+		t.Fatalf("stale clear recovery date = %d, want unchanged 1700000302", recoveryDate)
+	}
 	afterClear, err := channels.GetChannel(ctx, friend.ID, channelID)
 	if err != nil {
 		t.Fatalf("get channel after clear: %v", err)
 	}
-	if afterClear.Dialog.TopMessageID != 0 {
+	if afterClear.Dialog.TopMessageID != sent.Message.ID ||
-		t.Fatalf("dialog after clear = %+v, want no visible top", afterClear.Dialog)
+		afterClear.Dialog.HistoryClearAnchorID != sent.Message.ID ||
+		afterClear.Dialog.UnreadCount != 0 {
+		t.Fatalf("dialog after clear = %+v, want owner-local anchored top %d", afterClear.Dialog, sent.Message.ID)
+	}
+	dialogsAfterClear, err := channels.GetChannelDialogs(ctx, friend.ID, []int64{channelID})
+	if err != nil {
+		t.Fatalf("get channel dialogs after clear: %v", err)
+	}
+	if len(dialogsAfterClear.Dialogs) != 1 ||
+		len(dialogsAfterClear.Messages) != 1 ||
+		!domain.IsChannelHistoryClearMessage(dialogsAfterClear.Messages[0]) ||
+		dialogsAfterClear.Messages[0].ID != sent.Message.ID ||
+		dialogsAfterClear.Messages[0].Body != "" {
+		t.Fatalf("dialog projection after clear = dialogs=%+v messages=%+v", dialogsAfterClear.Dialogs, dialogsAfterClear.Messages)
+	}
+	projectedHistory, err := channels.ListChannelHistory(ctx, friend.ID, domain.ChannelHistoryFilter{
+		ChannelID:                 channelID,
+		Limit:                     10,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("project history-clear anchor: %v", err)
+	}
+	if len(projectedHistory.Messages) != 1 ||
+		!domain.IsChannelHistoryClearMessage(projectedHistory.Messages[0]) ||
+		projectedHistory.Messages[0].ID != sent.Message.ID {
+		t.Fatalf("projected history after clear = %+v, want anchor %d", projectedHistory.Messages, sent.Message.ID)
+	}
+	ownerDialogsAfterClear, err := channels.GetChannelDialogs(ctx, owner.ID, []int64{channelID})
+	if err != nil {
+		t.Fatalf("get unaffected owner dialog after friend clear: %v", err)
+	}
+	if len(ownerDialogsAfterClear.Messages) != 1 ||
+		ownerDialogsAfterClear.Messages[0].ID != sent.Message.ID ||
+		ownerDialogsAfterClear.Messages[0].Body != "first visible channel text" ||
+		ownerDialogsAfterClear.Messages[0].Action != nil {
+		t.Fatalf("friend clear changed shared owner projection: %+v", ownerDialogsAfterClear.Messages)
 	}
 
 	next, err := channels.SendChannelMessage(ctx, domain.SendChannelMessageRequest{
@@ -238,6 +361,59 @@ WHERE channel_id = $1 AND user_id = $2`, channelID, owner.ID).Scan(&ownerMemberR
 	if afterNext.Dialog.TopMessageID != next.Message.ID || afterNext.Dialog.UnreadCount != 1 {
 		t.Fatalf("dialog after next = %+v, want top %d unread 1", afterNext.Dialog, next.Message.ID)
 	}
+	firstPage, err := channels.ListChannelHistory(ctx, friend.ID, domain.ChannelHistoryFilter{
+		ChannelID:                 channelID,
+		Limit:                     1,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("list first page after next message: %v", err)
+	}
+	if len(firstPage.Messages) != 1 ||
+		firstPage.Messages[0].ID != next.Message.ID ||
+		firstPage.Count != 2 {
+		t.Fatalf("first page after next = %+v count=%d, want next message and bounded has-more count", firstPage.Messages, firstPage.Count)
+	}
+	offsetPage, err := channels.ListChannelHistory(ctx, friend.ID, domain.ChannelHistoryFilter{
+		ChannelID:                 channelID,
+		AddOffset:                 1,
+		Limit:                     1,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("list add-offset page after next message: %v", err)
+	}
+	if len(offsetPage.Messages) != 1 ||
+		offsetPage.Messages[0].ID != sent.Message.ID ||
+		!domain.IsChannelHistoryClearMessage(offsetPage.Messages[0]) {
+		t.Fatalf("add-offset page after next = %+v, want retained clear anchor %d", offsetPage.Messages, sent.Message.ID)
+	}
+	exactCount, err := channels.ListChannelHistory(ctx, friend.ID, domain.ChannelHistoryFilter{
+		ChannelID:                 channelID,
+		CountOnly:                 true,
+		NeedTotalCount:            true,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("count history after next message: %v", err)
+	}
+	if exactCount.Count != 2 {
+		t.Fatalf("exact history count after next = %d, want shared message plus clear anchor", exactCount.Count)
+	}
+	olderPage, err := channels.ListChannelHistory(ctx, friend.ID, domain.ChannelHistoryFilter{
+		ChannelID:                 channelID,
+		OffsetID:                  next.Message.ID,
+		Limit:                     10,
+		IncludeHistoryClearAnchor: true,
+	})
+	if err != nil {
+		t.Fatalf("list older page after next message: %v", err)
+	}
+	if len(olderPage.Messages) != 1 ||
+		olderPage.Messages[0].ID != sent.Message.ID ||
+		!domain.IsChannelHistoryClearMessage(olderPage.Messages[0]) {
+		t.Fatalf("older page after next = %+v, want retained clear anchor %d", olderPage.Messages, sent.Message.ID)
+	}
 }
 
 func TestChannelStoreStoryMessageForwardsPublicOnlyAndDeleteRollbackPostgres(t *testing.T) {

internal/store/postgres/channel_read_integration_test.go

@@ -574,8 +574,10 @@ WHERE channel_id = $1 AND user_id = $2`, channelID, member.ID).Scan(&storedTop,
 	if err != nil {
 		t.Fatalf("get large channel after local clear: %v", err)
 	}
-	if afterClear.Dialog.TopMessageID != 0 || afterClear.Dialog.UnreadCount != 0 {
+	if afterClear.Dialog.TopMessageID != sent.Message.ID ||
-		t.Fatalf("large dialog after local clear = %+v, want no visible unread top", afterClear.Dialog)
+		afterClear.Dialog.HistoryClearAnchorID != sent.Message.ID ||
+		afterClear.Dialog.UnreadCount != 0 {
+		t.Fatalf("large dialog after local clear = %+v, want anchored top %d with no unread", afterClear.Dialog, sent.Message.ID)
 	}
 }
 

internal/store/postgres/star_gift_lifecycle_migration_integration_test.go

@@ -14,7 +14,7 @@ func TestStarGiftLifecycleMigrationsApply(t *testing.T) {
 	if err != nil {
 		t.Fatalf("migrate star gift lifecycle schema: %v", err)
 	}
-	if status.Dirty || status.Empty || status.Version != 158 {
+	if status.Dirty || status.Empty || status.Version != 162 {
-		t.Fatalf("migration status = %+v, want clean version 158", status)
+		t.Fatalf("migration status = %+v, want clean version 162", status)
 	}
 }