[release-10.11] Tighten thread membership cleanup on team membership changes (#37081)

* Tighten thread membership cleanup on team membership changes (#36764)

* Tighten thread membership cleanup on team membership changes

Ensure ThreadMembership rows are cleaned up when a user is removed
from or leaves a team, add a defense-in-depth filter on the thread
retrieval path so memberships referencing channels the user is no
longer a member of are excluded, and add a one-time migration to
clean up stale records on existing deployments.

https://mattermost.atlassian.net/browse/MM-69008

* Centralize per-channel membership removal and tighten tests

Extract the combined channel-member and thread-membership removal into
a shared helper used by both removeUserFromChannel and LeaveTeam, so
future code paths cannot revoke channel access without dropping the
dependent thread state. The channel-leave event is now logged after
the combined removal completes.

Also drop verbose test header comments and rename a test to a
behavior-focused name.

* Backfill channel members in thread storetest setups

The new ChannelMembers predicate on thread read queries filters out
ThreadMembership rows whose user has no ChannelMembers row for the
thread's channel. Several existing storetest setups bypassed the
normal write path and inserted threads/memberships without channel
members. Add the missing channel-member rows so the test data matches
the real-world invariant.

* Retrigger enterprise CI

Pick up enterprise merge e6953d4 (master into
MM-69008-thread-membership-team-leave) in the combined Enterprise
CI/tests lane, which pins the enterprise SHA at mattermost-side
dispatch time.

Co-authored-by: Maria A Nunez <maria.nunez@mattermost.com>

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Cursor Agent <cursoragent@cursor.com>

* Add MySQL migration for 000195_threadmemberships_cleanup_v2

Co-authored-by: Cursor <cursoragent@cursor.com>

* Apply pre-commit lint fixes

Co-authored-by: Cursor <cursoragent@cursor.com>

* Retrigger CI

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Cursor Agent <cursoragent@cursor.com>

server/channels/api4/user_test.go

@@ -7711,6 +7711,63 @@ func TestGetThreadsForUser(t *testing.T) {
 	})
 }
 
+func TestGetThreadsForUser_AfterTeamRemovalAndReinvite(t *testing.T) {
+	mainHelper.Parallel(t)
+	th := Setup(t).InitBasic()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.CollapsedThreadsDefaultOn
+	})
+	th.App.Srv().SetLicense(model.NewTestLicenseSKU(model.LicenseShortSkuProfessional))
+
+	admin := th.BasicUser
+	victim := th.BasicUser2
+
+	privateChannel := th.CreatePrivateChannel()
+	th.AddUserToChannel(victim, privateChannel)
+
+	defer func() {
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, admin.Id))
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, victim.Id))
+	}()
+
+	rootPost, _, err := th.Client.CreatePost(context.Background(), &model.Post{
+		ChannelId: privateChannel.Id,
+		Message:   "private team secret",
+	})
+	require.NoError(t, err)
+
+	victimClient := th.CreateClient()
+	th.LoginBasic2WithClient(victimClient)
+
+	_, _, err = victimClient.CreatePost(context.Background(), &model.Post{
+		ChannelId: privateChannel.Id,
+		RootId:    rootPost.Id,
+		Message:   "victim reply",
+	})
+	require.NoError(t, err)
+
+	uss, _, err := victimClient.GetUserThreads(context.Background(), victim.Id, th.BasicTeam.Id, model.GetUserThreadsOpts{Extended: true})
+	require.NoError(t, err)
+	require.Len(t, uss.Threads, 1, "sanity: victim should see their own thread before team removal")
+
+	_, err = th.SystemAdminClient.RemoveTeamMember(context.Background(), th.BasicTeam.Id, victim.Id)
+	require.NoError(t, err)
+
+	_, _, err = th.SystemAdminClient.AddTeamMember(context.Background(), th.BasicTeam.Id, victim.Id)
+	require.NoError(t, err)
+
+	th.LoginBasic2WithClient(victimClient)
+
+	uss, _, err = victimClient.GetUserThreads(context.Background(), victim.Id, th.BasicTeam.Id, model.GetUserThreadsOpts{Extended: true})
+	require.NoError(t, err)
+	for _, thr := range uss.Threads {
+		require.NotEqual(t, rootPost.Id, thr.PostId, "private-channel thread must not leak to re-invited user")
+	}
+	require.Len(t, uss.Threads, 0, "re-invited user must not receive any threads from private channels they no longer belong to")
+}
+
 func TestThreadSocketEvents(t *testing.T) {
 	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()

server/channels/app/channel.go

@@ -2668,6 +2668,19 @@ func (a *App) postRemoveFromChannelMessage(c request.CTX, removerUserId string,
 	return nil
 }
 
+// removeChannelMembership strips a user's channel membership and the associated
+// thread memberships. Keeping these together ensures channel access cannot be
+// revoked without also dropping the thread state that depends on it.
+func (a *App) removeChannelMembership(rctx request.CTX, userID, channelID, caller string) *model.AppError {
+	if err := a.Srv().Store().Channel().RemoveMember(rctx, channelID, userID); err != nil {
+		return model.NewAppError(caller, "app.channel.remove_member.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
+	}
+	if err := a.Srv().Store().Thread().DeleteMembershipsForChannel(userID, channelID); err != nil {
+		return model.NewAppError(caller, model.NoTranslation, nil, "failed to delete threadmemberships upon leaving channel", http.StatusInternalServerError).Wrap(err)
+	}
+	return nil
+}
+
 func (a *App) removeUserFromChannel(c request.CTX, userIDToRemove string, removerUserId string, channel *model.Channel) *model.AppError {
 	user, nErr := a.Srv().Store().User().Get(context.Background(), userIDToRemove)
 	if nErr != nil {
@@ -2702,15 +2715,12 @@ func (a *App) removeUserFromChannel(c request.CTX, userIDToRemove string, remove
 		return err
 	}
 
-	if err := a.Srv().Store().Channel().RemoveMember(c, channel.Id, userIDToRemove); err != nil {
-		return model.NewAppError("removeUserFromChannel", "app.channel.remove_member.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
+	if appErr := a.removeChannelMembership(c, userIDToRemove, channel.Id, "removeUserFromChannel"); appErr != nil {
+		return appErr
 	}
 	if err := a.Srv().Store().ChannelMemberHistory().LogLeaveEvent(userIDToRemove, channel.Id, model.GetMillis()); err != nil {
 		return model.NewAppError("removeUserFromChannel", "app.channel_member_history.log_leave_event.internal_error", nil, "", http.StatusInternalServerError).Wrap(err)
 	}
-	if err := a.Srv().Store().Thread().DeleteMembershipsForChannel(userIDToRemove, channel.Id); err != nil {
-		return model.NewAppError("removeUserFromChannel", model.NoTranslation, nil, "failed to delete threadmemberships upon leaving channel", http.StatusInternalServerError).Wrap(err)
-	}
 
 	if isGuest {
 		currentMembers, err := a.GetChannelMembersForUser(c, channel.TeamId, userIDToRemove)

server/channels/app/team.go

@@ -1237,8 +1237,8 @@ func (a *App) LeaveTeam(c request.CTX, team *model.Team, user *model.User, reque
 	for _, channel := range channelList {
 		if !channel.IsGroupOrDirect() {
 			a.invalidateCacheForChannelMembers(channel.Id)
-			if nErr = a.Srv().Store().Channel().RemoveMember(c, channel.Id, user.Id); nErr != nil {
-				return model.NewAppError("LeaveTeam", "app.channel.remove_member.app_error", nil, "", http.StatusInternalServerError).Wrap(nErr)
+			if appErr := a.removeChannelMembership(c, user.Id, channel.Id, "LeaveTeam"); appErr != nil {
+				return appErr
 			}
 		}
 	}

server/channels/app/team_test.go

@@ -1139,6 +1139,256 @@ func TestLeaveTeamPanic(t *testing.T) {
 	}, "unexpected panic from LeaveTeam")
 }
 
+func TestLeaveTeamCleansUpThreadMemberships(t *testing.T) {
+	mainHelper.Parallel(t)
+	th := Setup(t).InitBasic()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.CollapsedThreadsDefaultOn
+	})
+	th.App.Srv().SetLicense(model.NewTestLicenseSKU(model.LicenseShortSkuProfessional))
+
+	admin := th.BasicUser
+	victim := th.BasicUser2
+
+	privateChannel := th.CreatePrivateChannel(th.Context, th.BasicTeam)
+	th.AddUserToChannel(victim, privateChannel)
+
+	rootPost, _, appErr := th.App.CreatePost(th.Context, &model.Post{
+		UserId:    admin.Id,
+		ChannelId: privateChannel.Id,
+		Message:   "private team secret",
+	}, privateChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+	defer func() {
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, admin.Id))
+	}()
+
+	_, _, appErr = th.App.CreatePost(th.Context, &model.Post{
+		UserId:    victim.Id,
+		ChannelId: privateChannel.Id,
+		RootId:    rootPost.Id,
+		Message:   "victim reply",
+	}, privateChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+	defer func() {
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, victim.Id))
+	}()
+
+	_, sErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rootPost.Id)
+	require.NoError(t, sErr, "victim should follow the thread after replying")
+
+	appErr = th.App.LeaveTeam(th.Context, th.BasicTeam, victim, victim.Id)
+	require.Nil(t, appErr)
+
+	_, gErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rootPost.Id)
+	var errNotFound *store.ErrNotFound
+	require.ErrorAs(t, gErr, &errNotFound, "thread membership must be deleted when user leaves the team")
+}
+
+func TestLeaveTeamCleansUpThreadMembershipsAcrossChannels(t *testing.T) {
+	mainHelper.Parallel(t)
+	th := Setup(t).InitBasic()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.CollapsedThreadsDefaultOn
+	})
+	th.App.Srv().SetLicense(model.NewTestLicenseSKU(model.LicenseShortSkuProfessional))
+
+	admin := th.BasicUser
+	victim := th.BasicUser2
+
+	privateA := th.CreatePrivateChannel(th.Context, th.BasicTeam)
+	privateB := th.CreatePrivateChannel(th.Context, th.BasicTeam)
+	openC := th.CreateChannel(th.Context, th.BasicTeam)
+	th.AddUserToChannel(victim, privateA)
+	th.AddUserToChannel(victim, privateB)
+	th.AddUserToChannel(victim, openC)
+
+	rootIDs := make([]string, 0, 3)
+	for _, ch := range []*model.Channel{privateA, privateB, openC} {
+		root, _, appErr := th.App.CreatePost(th.Context, &model.Post{
+			UserId:    admin.Id,
+			ChannelId: ch.Id,
+			Message:   "root in " + ch.Id,
+		}, ch, model.CreatePostFlags{SetOnline: true})
+		require.Nil(t, appErr)
+		_, _, appErr = th.App.CreatePost(th.Context, &model.Post{
+			UserId:    victim.Id,
+			ChannelId: ch.Id,
+			RootId:    root.Id,
+			Message:   "reply",
+		}, ch, model.CreatePostFlags{SetOnline: true})
+		require.Nil(t, appErr)
+		rootIDs = append(rootIDs, root.Id)
+	}
+	defer func() {
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, admin.Id))
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, victim.Id))
+	}()
+
+	for _, rid := range rootIDs {
+		_, sErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rid)
+		require.NoError(t, sErr, "sanity: victim should follow each thread")
+	}
+
+	appErr := th.App.LeaveTeam(th.Context, th.BasicTeam, victim, victim.Id)
+	require.Nil(t, appErr)
+
+	var errNotFound *store.ErrNotFound
+	for _, rid := range rootIDs {
+		_, gErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rid)
+		require.ErrorAs(t, gErr, &errNotFound, "thread membership for %s must be deleted on team leave", rid)
+	}
+}
+
+func TestLeaveTeamPreservesDMThreadMemberships(t *testing.T) {
+	mainHelper.Parallel(t)
+	th := Setup(t).InitBasic()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.CollapsedThreadsDefaultOn
+	})
+	th.App.Srv().SetLicense(model.NewTestLicenseSKU(model.LicenseShortSkuProfessional))
+
+	admin := th.BasicUser
+	victim := th.BasicUser2
+
+	dmChannel, appErr := th.App.GetOrCreateDirectChannel(th.Context, admin.Id, victim.Id)
+	require.Nil(t, appErr)
+
+	dmRoot, _, appErr := th.App.CreatePost(th.Context, &model.Post{
+		UserId:    admin.Id,
+		ChannelId: dmChannel.Id,
+		Message:   "dm root",
+	}, dmChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+	_, _, appErr = th.App.CreatePost(th.Context, &model.Post{
+		UserId:    victim.Id,
+		ChannelId: dmChannel.Id,
+		RootId:    dmRoot.Id,
+		Message:   "dm reply",
+	}, dmChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+	defer func() {
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, admin.Id))
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, victim.Id))
+	}()
+
+	_, sErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, dmRoot.Id)
+	require.NoError(t, sErr, "sanity: victim should follow the DM thread")
+
+	appErr = th.App.LeaveTeam(th.Context, th.BasicTeam, victim, victim.Id)
+	require.Nil(t, appErr)
+
+	_, gErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, dmRoot.Id)
+	require.NoError(t, gErr, "DM thread membership must survive leaving an unrelated team")
+}
+
+func TestGetThreadsForUser_ReadPathRejectsOrphanThreadMembership(t *testing.T) {
+	mainHelper.Parallel(t)
+	th := Setup(t).InitBasic()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.CollapsedThreadsDefaultOn
+	})
+	th.App.Srv().SetLicense(model.NewTestLicenseSKU(model.LicenseShortSkuProfessional))
+
+	admin := th.BasicUser
+	victim := th.BasicUser2
+
+	privateChannel := th.CreatePrivateChannel(th.Context, th.BasicTeam)
+	th.AddUserToChannel(victim, privateChannel)
+
+	rootPost, _, appErr := th.App.CreatePost(th.Context, &model.Post{
+		UserId:    admin.Id,
+		ChannelId: privateChannel.Id,
+		Message:   "private team secret",
+	}, privateChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+	defer func() {
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, admin.Id))
+		require.NoError(t, th.App.Srv().Store().Post().PermanentDeleteByUser(th.Context, victim.Id))
+	}()
+
+	_, _, appErr = th.App.CreatePost(th.Context, &model.Post{
+		UserId:    victim.Id,
+		ChannelId: privateChannel.Id,
+		RootId:    rootPost.Id,
+		Message:   "victim reply",
+	}, privateChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+
+	_, sErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rootPost.Id)
+	require.NoError(t, sErr, "sanity: victim should follow the thread after replying")
+
+	require.NoError(t, th.App.Srv().Store().Channel().RemoveMember(th.Context, privateChannel.Id, victim.Id))
+
+	_, sErr2 := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rootPost.Id)
+	require.NoError(t, sErr2, "sanity: synthetic orphan ThreadMembership must remain")
+
+	threads, gErr := th.App.Srv().Store().Thread().GetThreadsForUser(victim.Id, th.BasicTeam.Id, model.GetUserThreadsOpts{})
+	require.NoError(t, gErr)
+	for _, thr := range threads {
+		require.NotEqual(t, rootPost.Id, thr.PostId, "read path must not surface threads from channels the user no longer belongs to")
+	}
+	require.Empty(t, threads, "GetThreadsForUser must filter out orphan ThreadMembership rows")
+
+	totalThreads, gErr := th.App.Srv().Store().Thread().GetTotalThreads(victim.Id, th.BasicTeam.Id, model.GetUserThreadsOpts{})
+	require.NoError(t, gErr)
+	require.Zero(t, totalThreads, "GetTotalThreads must not count orphan ThreadMembership rows")
+
+	totalUnread, gErr := th.App.Srv().Store().Thread().GetTotalUnreadThreads(victim.Id, th.BasicTeam.Id, model.GetUserThreadsOpts{})
+	require.NoError(t, gErr)
+	require.Zero(t, totalUnread, "GetTotalUnreadThreads must not count orphan ThreadMembership rows")
+}
+
+func TestPermanentDeleteChannelRemovesThreadMemberships(t *testing.T) {
+	mainHelper.Parallel(t)
+	th := Setup(t).InitBasic()
+
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.CollapsedThreadsDefaultOn
+	})
+	th.App.Srv().SetLicense(model.NewTestLicenseSKU(model.LicenseShortSkuProfessional))
+
+	admin := th.BasicUser
+	victim := th.BasicUser2
+
+	privateChannel := th.CreatePrivateChannel(th.Context, th.BasicTeam)
+	th.AddUserToChannel(victim, privateChannel)
+
+	rootPost, _, appErr := th.App.CreatePost(th.Context, &model.Post{
+		UserId:    admin.Id,
+		ChannelId: privateChannel.Id,
+		Message:   "doomed root",
+	}, privateChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+
+	_, _, appErr = th.App.CreatePost(th.Context, &model.Post{
+		UserId:    victim.Id,
+		ChannelId: privateChannel.Id,
+		RootId:    rootPost.Id,
+		Message:   "doomed reply",
+	}, privateChannel, model.CreatePostFlags{SetOnline: true})
+	require.Nil(t, appErr)
+
+	_, sErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rootPost.Id)
+	require.NoError(t, sErr, "victim should follow the thread after replying")
+
+	appErr = th.App.PermanentDeleteChannel(th.Context, privateChannel)
+	require.Nil(t, appErr)
+
+	_, gErr := th.App.Srv().Store().Thread().GetMembershipForUser(victim.Id, rootPost.Id)
+	var errNotFound *store.ErrNotFound
+	require.ErrorAs(t, gErr, &errNotFound, "thread membership must be deleted with the channel")
+}
+
 func TestAppUpdateTeamScheme(t *testing.T) {
 	mainHelper.Parallel(t)
 	th := Setup(t).InitBasic()

server/channels/db/migrations/migrations.list

@@ -285,6 +285,8 @@ channels/db/migrations/mysql/000143_backfill_roles_schemeid.down.sql
 channels/db/migrations/mysql/000143_backfill_roles_schemeid.up.sql
 channels/db/migrations/mysql/000144_add_roles_schemeid_index.down.sql
 channels/db/migrations/mysql/000144_add_roles_schemeid_index.up.sql
+channels/db/migrations/mysql/000195_threadmemberships_cleanup_v2.down.sql
+channels/db/migrations/mysql/000195_threadmemberships_cleanup_v2.up.sql
 channels/db/migrations/postgres/000001_create_teams.down.sql
 channels/db/migrations/postgres/000001_create_teams.up.sql
 channels/db/migrations/postgres/000002_create_team_members.down.sql
@@ -571,3 +573,5 @@ channels/db/migrations/postgres/000143_backfill_roles_schemeid.down.sql
 channels/db/migrations/postgres/000143_backfill_roles_schemeid.up.sql
 channels/db/migrations/postgres/000144_add_roles_schemeid_index.down.sql
 channels/db/migrations/postgres/000144_add_roles_schemeid_index.up.sql
+channels/db/migrations/postgres/000195_threadmemberships_cleanup_v2.down.sql
+channels/db/migrations/postgres/000195_threadmemberships_cleanup_v2.up.sql

server/channels/db/migrations/mysql/000195_threadmemberships_cleanup_v2.down.sql

@@ -0,0 +1 @@
+-- Skipping it because the forward migration is destructive

server/channels/db/migrations/mysql/000195_threadmemberships_cleanup_v2.up.sql

@@ -0,0 +1,7 @@
+-- Drop ThreadMembership rows whose user is no longer a member of the thread's channel.
+DELETE tm
+FROM ThreadMemberships AS tm
+JOIN Threads ON Threads.PostId = tm.PostId
+LEFT JOIN ChannelMembers ON ChannelMembers.UserId = tm.UserId
+    AND Threads.ChannelId = ChannelMembers.ChannelId
+WHERE ChannelMembers.ChannelId IS NULL;

server/channels/db/migrations/postgres/000195_threadmemberships_cleanup_v2.down.sql

@@ -0,0 +1 @@
+-- Skipping it because the forward migration is destructive

server/channels/db/migrations/postgres/000195_threadmemberships_cleanup_v2.up.sql

@@ -0,0 +1,13 @@
+-- Drop ThreadMembership rows whose user is no longer a member of the thread's channel.
+DELETE FROM threadmemberships WHERE (postid, userid) IN (
+    SELECT
+        threadmemberships.postid,
+        threadmemberships.userid
+    FROM
+        threadmemberships
+        JOIN threads ON threads.postid = threadmemberships.postid
+        LEFT JOIN channelmembers ON channelmembers.userid = threadmemberships.userid
+            AND threads.channelid = channelmembers.channelid
+    WHERE
+        channelmembers.channelid IS NULL
+);

server/channels/store/sqlstore/thread_store.go

@@ -70,6 +70,17 @@ type SqlThreadStore struct {
 func (s *SqlThreadStore) ClearCaches() {
 }
 
+// channelMembershipPredicate filters out ThreadMemberships whose user is no
+// longer a member of the thread's channel. DM/GM threads have an empty
+// ThreadTeamId and are exempt because their access is intrinsic to the
+// channel members.
+func channelMembershipPredicate() sq.Sqlizer {
+	return sq.Or{
+		sq.Eq{"Threads.ThreadTeamId": ""},
+		sq.Expr("EXISTS (SELECT 1 FROM ChannelMembers WHERE ChannelMembers.ChannelId = Threads.ChannelId AND ChannelMembers.UserId = ThreadMemberships.UserId)"),
+	}
+}
+
 func newSqlThreadStore(sqlStore *SqlStore) store.ThreadStore {
 	s := SqlThreadStore{
 		SqlStore: sqlStore,
@@ -131,7 +142,8 @@ func (s *SqlThreadStore) getTotalThreadsQuery(userId, teamId string, opts model.
 		Where(sq.Eq{
 			"ThreadMemberships.UserId":    userId,
 			"ThreadMemberships.Following": true,
-		})
+		}).
+		Where(channelMembershipPredicate())
 
 	if teamId != "" {
 		if opts.ExcludeDirect {
@@ -198,7 +210,8 @@ func (s *SqlThreadStore) GetTotalUnreadMentions(userId, teamId string, opts mode
 		Where(sq.Eq{
 			"ThreadMemberships.UserId":    userId,
 			"ThreadMemberships.Following": true,
-		})
+		}).
+		Where(channelMembershipPredicate())
 
 	if teamId != "" {
 		if opts.ExcludeDirect {
@@ -234,15 +247,13 @@ func (s *SqlThreadStore) GetTotalUnreadUrgentMentions(userId, teamId string, opt
 		Select("COALESCE(SUM(ThreadMemberships.UnreadMentions),0)").
 		From("ThreadMemberships").
 		Join("PostsPriority ON PostsPriority.PostId = ThreadMemberships.PostId").
+		Join("Threads ON Threads.PostId = ThreadMemberships.PostId").
 		Where(sq.Eq{
 			"ThreadMemberships.UserId":    userId,
 			"ThreadMemberships.Following": true,
 			"PostsPriority.Priority":      model.PostPriorityUrgent,
-		})
-
-	if teamId != "" || !opts.Deleted {
-		query = query.Join("Threads ON Threads.PostId = ThreadMemberships.PostId")
-	}
+		}).
+		Where(channelMembershipPredicate())
 
 	if teamId != "" {
 		if opts.ExcludeDirect {
@@ -298,7 +309,8 @@ func (s *SqlThreadStore) GetThreadsForUser(userId, teamId string, opts model.Get
 
 	query = query.
 		Where(sq.Eq{"ThreadMemberships.UserId": userId}).
-		Where(sq.Eq{"ThreadMemberships.Following": true})
+		Where(sq.Eq{"ThreadMemberships.Following": true}).
+		Where(channelMembershipPredicate())
 
 	if opts.IncludeIsUrgent {
 		urgencyCase := sq.
@@ -405,6 +417,7 @@ func (s *SqlThreadStore) GetTeamsUnreadForUser(userID string, teamIDs []string,
 		sq.Eq{"ThreadMemberships.Following": true},
 		sq.Eq{"Threads.ThreadTeamId": teamIDs},
 		sq.Eq{"COALESCE(Threads.ThreadDeleteAt, 0)": 0},
+		channelMembershipPredicate(),
 	}
 
 	var eg errgroup.Group

server/channels/store/storetest/thread_store.go

@@ -717,6 +717,12 @@ func testGetTeamsUnreadForUser(t *testing.T, rctx request.CTX, ss store.Store) {
 		Type:        model.ChannelTypeOpen,
 	}, -1)
 	require.NoError(t, err)
+	_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+		ChannelId:   channel1.Id,
+		UserId:      userID,
+		NotifyProps: model.GetDefaultChannelNotifyProps(),
+	})
+	require.NoError(t, err)
 	post, err := ss.Post().Save(rctx, &model.Post{
 		ChannelId: channel1.Id,
 		UserId:    userID,
@@ -759,6 +765,12 @@ func testGetTeamsUnreadForUser(t *testing.T, rctx request.CTX, ss store.Store) {
 		Type:        model.ChannelTypeOpen,
 	}, -1)
 	require.NoError(t, err)
+	_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+		ChannelId:   channel2.Id,
+		UserId:      userID,
+		NotifyProps: model.GetDefaultChannelNotifyProps(),
+	})
+	require.NoError(t, err)
 
 	post2, err := ss.Post().Save(rctx, &model.Post{
 		ChannelId: channel2.Id,
@@ -869,6 +881,12 @@ func testVarious(t *testing.T, rctx request.CTX, ss store.Store) {
 		Type:        model.ChannelTypeOpen,
 	}, -1)
 	require.NoError(t, err)
+	_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+		ChannelId:   team1channel1.Id,
+		UserId:      user1ID,
+		NotifyProps: model.GetDefaultChannelNotifyProps(),
+	})
+	require.NoError(t, err)
 
 	team2channel1, err := ss.Channel().Save(rctx, &model.Channel{
 		TeamId:      team2.Id,
@@ -877,6 +895,12 @@ func testVarious(t *testing.T, rctx request.CTX, ss store.Store) {
 		Type:        model.ChannelTypeOpen,
 	}, -1)
 	require.NoError(t, err)
+	_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+		ChannelId:   team2channel1.Id,
+		UserId:      user1ID,
+		NotifyProps: model.GetDefaultChannelNotifyProps(),
+	})
+	require.NoError(t, err)
 
 	dm1, err := ss.Channel().CreateDirectChannel(rctx, &model.User{Id: user1ID}, &model.User{Id: user2ID})
 	require.NoError(t, err)
@@ -1345,6 +1369,17 @@ func testMarkAllAsReadByChannels(t *testing.T, rctx request.CTX, ss store.Store)
 	}, -1)
 	require.NoError(t, err)
 
+	for _, ch := range []*model.Channel{channel1, channel2} {
+		for _, uid := range []string{userAID, userBID} {
+			_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+				ChannelId:   ch.Id,
+				UserId:      uid,
+				NotifyProps: model.GetDefaultChannelNotifyProps(),
+			})
+			require.NoError(t, err)
+		}
+	}
+
 	createThreadMembership := func(userID, postID string) {
 		t.Helper()
 		opts := store.ThreadMembershipOpts{
@@ -1535,6 +1570,17 @@ func testMarkAllAsReadByTeam(t *testing.T, rctx request.CTX, ss store.Store) {
 	}, -1)
 	require.NoError(t, err)
 
+	for _, ch := range []*model.Channel{team1channel1, team1channel2, team2channel1, team2channel2} {
+		for _, uid := range []string{userAID, userBID} {
+			_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+				ChannelId:   ch.Id,
+				UserId:      uid,
+				NotifyProps: model.GetDefaultChannelNotifyProps(),
+			})
+			require.NoError(t, err)
+		}
+	}
+
 	team1channel1post1, err := ss.Post().Save(rctx, &model.Post{
 		ChannelId: team1channel1.Id,
 		UserId:    postingUserId,
@@ -2110,6 +2156,13 @@ func testUpdateTeamIdForChannelThreads(t *testing.T, rctx request.CTX, ss store.
 		})
 		require.NoError(t, err)
 
+		_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+			ChannelId:   channel1.Id,
+			UserId:      userA.Id,
+			NotifyProps: model.GetDefaultChannelNotifyProps(),
+		})
+		require.NoError(t, err)
+
 		_, clean := createThreadMembership(userA.Id, rootPost1.Id, true)
 		defer clean()
 
@@ -2134,6 +2187,13 @@ func testUpdateTeamIdForChannelThreads(t *testing.T, rctx request.CTX, ss store.
 		})
 		require.NoError(t, err)
 
+		_, err = ss.Channel().SaveMember(rctx, &model.ChannelMember{
+			ChannelId:   channel1.Id,
+			UserId:      userA.Id,
+			NotifyProps: model.GetDefaultChannelNotifyProps(),
+		})
+		require.NoError(t, err)
+
 		newTeamID := model.NewId()
 
 		_, clean := createThreadMembership(userA.Id, rootPost1.Id, true)