From 5156b17c1b3dfd7256cc79972cb78191781147e4 Mon Sep 17 00:00:00 2001
From: iamxvbaba <28732408+iamxvbaba@users.noreply.github.com>
Date: Tue, 28 Jul 2026 16:22:34 +0800
Subject: [PATCH] fix(usernames): sync index active collectible aliases

---
 .../0160_peer_username_search.down.sql        |   1 +
 .../0160_peer_username_search.up.sql          |   6 +
 internal/app/channels/service.go              |   5 +-
 internal/app/channels/service_test.go         |  52 +++++-
 internal/app/contacts/service_test.go         |  40 +++++
 internal/app/users/service.go                 |   6 +-
 internal/app/users/service_test.go            |  28 +++
 .../rpc/collectible_usernames_rpc_test.go     |  39 +++--
 internal/rpc/contacts_users_rpc_test.go       |  30 +++-
 internal/rpc/fragment.go                      |  20 ++-
 internal/rpc/username_notify_test.go          |  20 +--
 internal/store/collectible_username.go        |   3 +-
 internal/store/memory/channel_core.go         |  11 +-
 internal/store/memory/channel_helpers.go      |  17 +-
 internal/store/memory/channel_members.go      |   2 +-
 .../store/memory/channel_message_history.go   |   2 +-
 internal/store/memory/channel_settings.go     |  22 ++-
 internal/store/memory/channel_store.go        |  11 +-
 internal/store/memory/collectible_username.go |  55 ++++++
 internal/store/memory/community.go            |   2 +-
 internal/store/memory/users.go                |  43 ++++-
 internal/store/postgres/channel_core.go       |  11 +-
 internal/store/postgres/channel_helpers.go    |  33 +++-
 internal/store/postgres/channel_settings.go   |   8 +-
 .../collectible_username_integration_test.go  | 159 ++++++++++++++++++
 internal/store/postgres/peer_username.go      |  33 ++++
 internal/store/postgres/queries/user.sql      |  17 +-
 internal/store/postgres/sqlcgen/user.sql.go   |  53 +++---
 internal/web/server.go                        |  40 ++---
 29 files changed, 657 insertions(+), 112 deletions(-)
 create mode 100644 deploy/migrations/0160_peer_username_search.down.sql
 create mode 100644 deploy/migrations/0160_peer_username_search.up.sql

diff --git a/deploy/migrations/0160_peer_username_search.down.sql b/deploy/migrations/0160_peer_username_search.down.sql
new file mode 100644
index 00000000..8f49984d
--- /dev/null
+++ b/deploy/migrations/0160_peer_username_search.down.sql
@@ -0,0 +1 @@
+DROP INDEX IF EXISTS public.peer_usernames_active_search_idx;
diff --git a/deploy/migrations/0160_peer_username_search.up.sql b/deploy/migrations/0160_peer_username_search.up.sql
new file mode 100644
index 00000000..b48b3ff5
--- /dev/null
+++ b/deploy/migrations/0160_peer_username_search.up.sql
@@ -0,0 +1,6 @@
+-- Active usernames are searched by peer type and a case-normalized prefix.
+-- text_pattern_ops keeps the lookup indexable even when the database collation
+-- cannot use a regular btree index for LIKE 'prefix%'.
+CREATE INDEX peer_usernames_active_search_idx
+    ON public.peer_usernames (peer_type, username_lower text_pattern_ops, peer_id)
+    WHERE active;
diff --git a/internal/app/channels/service.go b/internal/app/channels/service.go
index 48d86681..f79d1ccf 100644
--- a/internal/app/channels/service.go
+++ b/internal/app/channels/service.go
@@ -597,7 +597,10 @@ func (s *Service) ResolvePublicUsername(ctx context.Context, userID int64, usern
 		return domain.Channel{}, false, domain.ErrChannelInvalid
 	}
 	username = normalizeChannelUsername(username)
-	if !validChannelUsername(username) {
+	// Public resolution also covers Fragment-style collectible usernames,
+	// whose protocol minimum is four characters. Channel username mutation
+	// remains on the ordinary 5..32 validation path above.
+	if !domain.ValidCollectibleUsername(username) {
 		return domain.Channel{}, false, domain.ErrUsernameInvalid
 	}
 	return s.channels.ResolvePublicChannelUsername(ctx, userID, username)
diff --git a/internal/app/channels/service_test.go b/internal/app/channels/service_test.go
index 427462ca..a8e7f908 100644
--- a/internal/app/channels/service_test.go
+++ b/internal/app/channels/service_test.go
@@ -2904,7 +2904,10 @@ func TestListSendAsChannelsFiltersPostMessageRights(t *testing.T) {
 
 func TestPublicChannelSearchAndResolveUsername(t *testing.T) {
 	ctx := context.Background()
-	service := NewService(memory.NewChannelStore())
+	channelStore := memory.NewChannelStore()
+	registry := memory.NewCollectibleUsernameStore()
+	channelStore.AttachUsernameRegistry(registry)
+	service := NewService(channelStore)
 	created, err := service.CreateMegagroupFromCreateChat(ctx, 1001, domain.CreateChannelRequest{
 		Title:         "CU Public Lab",
 		MemberUserIDs: []int64{1002},
@@ -2945,6 +2948,53 @@ func TestPublicChannelSearchAndResolveUsername(t *testing.T) {
 	if err != nil || !found || resolved.ID != public.ID {
 		t.Fatalf("ResolvePublicUsername = %+v found %v err %v, want public channel", resolved, found, err)
 	}
+	peer := domain.Peer{Type: domain.PeerTypeChannel, ID: public.ID}
+	if _, created, err := registry.MintCollectibleUsername(ctx, domain.MintCollectibleUsernameRequest{
+		Username: "nfc4",
+		Owner:    peer,
+		Currency: domain.CollectibleCurrencyStars,
+		Amount:   1,
+		Actor:    "test",
+	}); err != nil || !created {
+		t.Fatalf("mint channel collectible: created=%v err=%v", created, err)
+	}
+	resolved, found, err = service.ResolvePublicUsername(ctx, 1003, "@NFC4")
+	if err != nil || !found || resolved.ID != public.ID {
+		t.Fatalf("ResolvePublicUsername collectible = %+v found %v err %v, want public channel", resolved, found, err)
+	}
+	collectibleSearch, err := service.SearchPublicChannels(ctx, 1003, "nfc", 10)
+	if err != nil || len(collectibleSearch.Results) != 1 || collectibleSearch.Results[0].ID != public.ID {
+		t.Fatalf("collectible channel search = %+v err=%v, want public channel", collectibleSearch, err)
+	}
+	if _, err := service.UpdateUsername(ctx, 1001, domain.UpdateChannelUsernameRequest{
+		ChannelID: public.ID,
+		Username:  "",
+	}); err != nil {
+		t.Fatalf("clear editable username: %v", err)
+	}
+	resolved, found, err = service.ResolvePublicUsername(ctx, 1003, "nfc4")
+	if err != nil || !found || resolved.ID != public.ID {
+		t.Fatalf("NFT-only ResolvePublicUsername = %+v found=%v err=%v", resolved, found, err)
+	}
+	if view, err := service.GetChannel(ctx, 1003, public.ID); err != nil || view.Channel.ID != public.ID {
+		t.Fatalf("NFT-only public preview = %+v err=%v", view, err)
+	}
+	if _, err := service.UpdateUsername(ctx, 1001, domain.UpdateChannelUsernameRequest{
+		ChannelID: public.ID,
+		Username:  "cu_public_lab",
+	}); err != nil {
+		t.Fatalf("restore editable username: %v", err)
+	}
+	if changed, err := registry.SetUsernameActive(ctx, peer, "nfc4", false); err != nil || !changed {
+		t.Fatalf("deactivate channel collectible: changed=%v err=%v", changed, err)
+	}
+	if _, found, err := service.ResolvePublicUsername(ctx, 1003, "nfc4"); err != nil || found {
+		t.Fatalf("inactive collectible resolve found=%v err=%v, want hidden", found, err)
+	}
+	hiddenSearch, err := service.SearchPublicChannels(ctx, 1003, "nfc4", 10)
+	if err != nil || len(hiddenSearch.Results) != 0 {
+		t.Fatalf("inactive collectible search = %+v err=%v, want empty", hiddenSearch, err)
+	}
 }
 
 func TestPublicChannelPreviewAllowsNonMemberHistory(t *testing.T) {
diff --git a/internal/app/contacts/service_test.go b/internal/app/contacts/service_test.go
index 17c9d705..c168edbc 100644
--- a/internal/app/contacts/service_test.go
+++ b/internal/app/contacts/service_test.go
@@ -644,6 +644,46 @@ func TestAcceptContactRequiresExistingContactRequest(t *testing.T) {
 	}
 }
 
+func TestSearchFindsOnlyActiveCollectibleUsernames(t *testing.T) {
+	ctx := context.Background()
+	users := memory.NewUserStore()
+	registry := memory.NewCollectibleUsernameStore()
+	users.AttachUsernameRegistry(registry)
+	viewer, err := users.Create(ctx, domain.User{Phone: "15550000101", FirstName: "Viewer"})
+	if err != nil {
+		t.Fatalf("create viewer: %v", err)
+	}
+	target, err := users.Create(ctx, domain.User{Phone: "15550000102", FirstName: "Unrelated", Username: "target_slot"})
+	if err != nil {
+		t.Fatalf("create target: %v", err)
+	}
+	peer := domain.Peer{Type: domain.PeerTypeUser, ID: target.ID}
+	if _, err := registry.SetEditableUsername(ctx, peer, target.Username); err != nil {
+		t.Fatalf("seed editable username: %v", err)
+	}
+	if _, created, err := registry.MintCollectibleUsername(ctx, domain.MintCollectibleUsernameRequest{
+		Username: "nft4",
+		Owner:    peer,
+		Currency: domain.CollectibleCurrencyStars,
+		Amount:   1,
+		Actor:    "test",
+	}); err != nil || !created {
+		t.Fatalf("mint collectible: created=%v err=%v", created, err)
+	}
+	svc := NewService(memory.NewContactStore(), users)
+	found, err := svc.Search(ctx, viewer.ID, "@NFT4", 10)
+	if err != nil || len(found.Results) != 1 || found.Results[0].ID != target.ID {
+		t.Fatalf("search active collectible = %+v err=%v, want target", found, err)
+	}
+	if changed, err := registry.SetUsernameActive(ctx, peer, "nft4", false); err != nil || !changed {
+		t.Fatalf("deactivate collectible: changed=%v err=%v", changed, err)
+	}
+	hidden, err := svc.Search(ctx, viewer.ID, "nft4", 10)
+	if err != nil || len(hidden.Results) != 0 || len(hidden.MyResults) != 0 {
+		t.Fatalf("search inactive collectible = %+v err=%v, want empty", hidden, err)
+	}
+}
+
 func contactByID(t *testing.T, list domain.ContactList, id int64) domain.Contact {
 	t.Helper()
 	for _, contact := range list.Contacts {
diff --git a/internal/app/users/service.go b/internal/app/users/service.go
index 97703e97..516476df 100644
--- a/internal/app/users/service.go
+++ b/internal/app/users/service.go
@@ -577,7 +577,11 @@ func (s *Service) ResolveUsername(ctx context.Context, currentUserID int64, user
 		return domain.User{}, false, err
 	}
 	username = normalizeUsername(username)
-	if !validUsername(username) {
+	// Resolution covers both the editable username slot (5..32) and
+	// Fragment-style collectible usernames (4..32). Keep the stricter
+	// validUsername check on create/update paths; only lookup accepts the
+	// collectible lower bound.
+	if !domain.ValidCollectibleUsername(username) {
 		return domain.User{}, false, domain.ErrUsernameInvalid
 	}
 	u, found, err := s.users.ByUsername(ctx, username)
diff --git a/internal/app/users/service_test.go b/internal/app/users/service_test.go
index f515a195..61499da5 100644
--- a/internal/app/users/service_test.go
+++ b/internal/app/users/service_test.go
@@ -45,6 +45,34 @@ func TestServiceUsernameLifecycle(t *testing.T) {
 	if err != nil || !found || resolved.ID != owner.ID {
 		t.Fatalf("ResolveUsername = user %+v found %v err %v, want owner", resolved, found, err)
 	}
+	registry := memory.NewCollectibleUsernameStore()
+	store.AttachUsernameRegistry(registry)
+	peer := domain.Peer{Type: domain.PeerTypeUser, ID: owner.ID}
+	if _, err := registry.SetEditableUsername(ctx, peer, updated.Username); err != nil {
+		t.Fatalf("seed editable username registry: %v", err)
+	}
+	if _, created, err := registry.MintCollectibleUsername(ctx, domain.MintCollectibleUsernameRequest{
+		Username: "nft4",
+		Owner:    peer,
+		Currency: domain.CollectibleCurrencyStars,
+		Amount:   1,
+		Actor:    "test",
+	}); err != nil || !created {
+		t.Fatalf("mint four-character collectible: created=%v err=%v", created, err)
+	}
+	resolved, found, err = svc.ResolveUsername(ctx, other.ID, "@NFT4")
+	if err != nil || !found || resolved.ID != owner.ID {
+		t.Fatalf("ResolveUsername collectible = user %+v found %v err %v, want owner", resolved, found, err)
+	}
+	if _, err := svc.UpdateUsername(ctx, owner.ID, "nft4"); !errors.Is(err, domain.ErrUsernameInvalid) {
+		t.Fatalf("four-character editable username err = %v, want username invalid", err)
+	}
+	if changed, err := registry.SetUsernameActive(ctx, peer, "nft4", false); err != nil || !changed {
+		t.Fatalf("deactivate collectible: changed=%v err=%v", changed, err)
+	}
+	if _, found, err := svc.ResolveUsername(ctx, other.ID, "nft4"); err != nil || found {
+		t.Fatalf("inactive collectible found=%v err=%v, want hidden", found, err)
+	}
 	if _, err := svc.UpdateUsername(ctx, owner.ID, "TAKEN_NAME"); !errors.Is(err, domain.ErrUsernameOccupied) {
 		t.Fatalf("UpdateUsername duplicate err = %v, want username occupied", err)
 	}
diff --git a/internal/rpc/collectible_usernames_rpc_test.go b/internal/rpc/collectible_usernames_rpc_test.go
index 9a3979a5..7cc54245 100644
--- a/internal/rpc/collectible_usernames_rpc_test.go
+++ b/internal/rpc/collectible_usernames_rpc_test.go
@@ -234,12 +234,12 @@ func TestUsersGetUsersProjectsCollectibleUsernamesInOneBatch(t *testing.T) {
 	registry := newFakeUsernameRegistry()
 	f := newUsernameProjectionFixture(t, registry)
 	registry.byPeer[domain.Peer{Type: domain.PeerTypeUser, ID: f.owner.ID}] = []domain.Username{
-		{Username: "owner_slot", Editable: true, Active: true},
-		{Username: "nft", Active: true, SortOrder: 0, CollectibleID: 7},
+		{Username: "owner_slot", Editable: true, Active: true, SortOrder: 1},
+		{Username: "nft4", Active: true, SortOrder: 0, CollectibleID: 7},
 	}
 	registry.byPeer[domain.Peer{Type: domain.PeerTypeUser, ID: f.friend.ID}] = []domain.Username{
 		{Username: "friend_slot", Editable: true, Active: true},
-		{Username: "gem", Active: false, SortOrder: 0, CollectibleID: 8},
+		{Username: "gem4", Active: false, SortOrder: 1, CollectibleID: 8},
 	}
 	ctx := WithUserID(context.Background(), f.owner.ID)
 
@@ -254,26 +254,29 @@ func TestUsersGetUsersProjectsCollectibleUsernamesInOneBatch(t *testing.T) {
 		t.Fatalf("users = %d, want 2", len(out))
 	}
 	self := out[0].(*tg.User)
-	if _, ok := self.GetUsername(); ok {
-		t.Fatalf("self scalar username is set together with collectible vector")
+	if scalar, ok := self.GetUsername(); !ok || scalar != "nft4" {
+		t.Fatalf("self scalar username = %q (set %v), want primary collectible nft4", scalar, ok)
 	}
 	vector, ok := self.GetUsernames()
 	if !ok {
 		t.Fatalf("self usernames unset, want registry vector")
 	}
-	if got := usernameStrings(vector); len(got) != 2 || got[0] != "owner_slot" || got[1] != "nft" {
-		t.Fatalf("self usernames = %v, want [owner_slot nft]", got)
+	if got := usernameStrings(vector); len(got) != 2 || got[0] != "nft4" || got[1] != "owner_slot" {
+		t.Fatalf("self usernames = %v, want [nft4 owner_slot]", got)
 	}
-	if !vector[0].Editable || !vector[0].Active {
-		t.Fatalf("editable slot flags = %+v, want editable+active", vector[0])
+	if vector[0].Editable || !vector[0].Active {
+		t.Fatalf("primary collectible flags = %+v, want non-editable+active", vector[0])
 	}
-	if vector[1].Editable || !vector[1].Active {
-		t.Fatalf("collectible flags = %+v, want non-editable+active", vector[1])
+	if !vector[1].Editable || !vector[1].Active {
+		t.Fatalf("editable slot flags = %+v, want editable+active", vector[1])
 	}
 	friend := out[1].(*tg.User)
+	if scalar, ok := friend.GetUsername(); !ok || scalar != "friend_slot" {
+		t.Fatalf("friend scalar username = %q (set %v), want friend_slot", scalar, ok)
+	}
 	friendVector, _ := friend.GetUsernames()
-	if got := usernameStrings(friendVector); len(got) != 2 || got[1] != "gem" {
-		t.Fatalf("friend usernames = %v, want [friend_slot gem]", got)
+	if got := usernameStrings(friendVector); len(got) != 2 || got[1] != "gem4" {
+		t.Fatalf("friend usernames = %v, want [friend_slot gem4]", got)
 	}
 	if friendVector[1].Active {
 		t.Fatalf("inactive collectible projected active: %+v", friendVector[1])
@@ -663,7 +666,7 @@ func TestChannelsGetChannelsProjectsCollectibleUsernames(t *testing.T) {
 	r, owner, channel := newCollectibleChannelFixture(t, registry)
 	ctx := WithUserID(context.Background(), owner.ID)
 	registry.byPeer[domain.Peer{Type: domain.PeerTypeChannel, ID: channel.ID}] = []domain.Username{
-		{Username: "chan_slot", Editable: true, Active: true},
+		{Username: "chan_slot", Editable: true, Active: true, SortOrder: 1},
 		{Username: "chan_nft", Active: true, SortOrder: 0, CollectibleID: 44},
 	}
 
@@ -681,11 +684,11 @@ func TestChannelsGetChannelsProjectsCollectibleUsernames(t *testing.T) {
 	if !ok {
 		t.Fatalf("channel usernames unset, want registry vector")
 	}
-	if got := usernameStrings(vector); len(got) != 2 || got[0] != "chan_slot" || got[1] != "chan_nft" {
-		t.Fatalf("channel usernames = %v, want [chan_slot chan_nft]", got)
+	if got := usernameStrings(vector); len(got) != 2 || got[0] != "chan_nft" || got[1] != "chan_slot" {
+		t.Fatalf("channel usernames = %v, want [chan_nft chan_slot]", got)
 	}
-	if scalar, ok := out[0].(*tg.Channel).GetUsername(); ok || scalar != "" {
-		t.Fatalf("scalar channel username = %q (set %v), want absent with collectible vector", scalar, ok)
+	if scalar, ok := out[0].(*tg.Channel).GetUsername(); !ok || scalar != "chan_nft" {
+		t.Fatalf("scalar channel username = %q (set %v), want primary collectible chan_nft", scalar, ok)
 	}
 }
 
diff --git a/internal/rpc/contacts_users_rpc_test.go b/internal/rpc/contacts_users_rpc_test.go
index 36134a28..0c198c7e 100644
--- a/internal/rpc/contacts_users_rpc_test.go
+++ b/internal/rpc/contacts_users_rpc_test.go
@@ -13,6 +13,7 @@ import (
 	appprivacy "telesrv/internal/app/privacy"
 	appstories "telesrv/internal/app/stories"
 	appupdates "telesrv/internal/app/updates"
+	usernamesapp "telesrv/internal/app/usernames"
 	"telesrv/internal/app/userprojection"
 	appusers "telesrv/internal/app/users"
 	"telesrv/internal/domain"
@@ -24,6 +25,8 @@ import (
 func TestContactsSearchFindsUsers(t *testing.T) {
 	ctx := context.Background()
 	users := memory.NewUserStore()
+	registry := memory.NewCollectibleUsernameStore()
+	users.AttachUsernameRegistry(registry)
 	owner, err := users.Create(ctx, domain.User{AccessHash: 1, Phone: "15550000001", FirstName: "Owner"})
 	if err != nil {
 		t.Fatalf("create owner: %v", err)
@@ -32,12 +35,29 @@ func TestContactsSearchFindsUsers(t *testing.T) {
 	if err != nil {
 		t.Fatalf("create friend: %v", err)
 	}
+	friendPeer := domain.Peer{Type: domain.PeerTypeUser, ID: friend.ID}
+	if _, err := registry.SetEditableUsername(ctx, friendPeer, friend.Username); err != nil {
+		t.Fatalf("seed editable username: %v", err)
+	}
+	if _, created, err := registry.MintCollectibleUsername(ctx, domain.MintCollectibleUsernameRequest{
+		Username: "nft4",
+		Owner:    friendPeer,
+		Currency: domain.CollectibleCurrencyStars,
+		Amount:   1,
+		Actor:    "test",
+	}); err != nil || !created {
+		t.Fatalf("mint collectible: created=%v err=%v", created, err)
+	}
 	r := New(Config{}, Deps{
 		Contacts: appcontacts.NewService(memory.NewContactStore(), users),
+		Usernames: usernamesapp.NewService(
+			usernamesapp.WithRegistryStore(registry),
+			usernamesapp.WithCollectibleStore(registry),
+		),
 	}, zaptest.NewLogger(t), clock.System)
 
 	var in bin.Buffer
-	if err := (&tg.ContactsSearchRequest{Q: "@search", Limit: 20}).Encode(&in); err != nil {
+	if err := (&tg.ContactsSearchRequest{Q: "@NFT4", Limit: 20}).Encode(&in); err != nil {
 		t.Fatalf("encode request: %v", err)
 	}
 	enc, err := r.Dispatch(WithUserID(ctx, owner.ID), [8]byte{}, 0, &in)
@@ -55,6 +75,14 @@ func TestContactsSearchFindsUsers(t *testing.T) {
 	if !ok || peer.UserID != friend.ID {
 		t.Fatalf("peer = %T %+v, want friend", box.Results[0], box.Results[0])
 	}
+	user := box.Users[0].(*tg.User)
+	if scalar, ok := user.GetUsername(); !ok || scalar != "search_friend" {
+		t.Fatalf("search result scalar username = %q (set %v), want search_friend", scalar, ok)
+	}
+	vector, ok := user.GetUsernames()
+	if !ok || len(vector) != 2 || vector[1].Username != "nft4" || !vector[1].Active {
+		t.Fatalf("search result username vector = %+v (set %v), want active nft4 alias", vector, ok)
+	}
 }
 
 func TestContactsEditCloseFriendsProjectsUserFlag(t *testing.T) {
diff --git a/internal/rpc/fragment.go b/internal/rpc/fragment.go
index 997d55cc..d0c16966 100644
--- a/internal/rpc/fragment.go
+++ b/internal/rpc/fragment.go
@@ -302,8 +302,16 @@ func applyUsernamesFromRegistry(users []tg.UserClass, chats []tg.ChatClass, byPe
 			continue
 		}
 		if vector := tgUsernamesFromRegistry(list, u.Username); len(vector) > 0 {
-			u.Flags.Unset(3)
-			u.Username = ""
+			// Layer 228 defines username as the main active username, not as a
+			// legacy alternative to usernames. TDesktop seeds its local search
+			// index from this scalar before consuming the complete vector, so
+			// both fields must be projected together.
+			if primary := domain.ActiveUsername(list); primary != "" {
+				u.SetUsername(primary)
+			} else {
+				u.Flags.Unset(3)
+				u.Username = ""
+			}
 			u.SetUsernames(vector)
 		}
 	}
@@ -320,8 +328,12 @@ func applyUsernamesFromRegistry(users []tg.UserClass, chats []tg.ChatClass, byPe
 		// when unset, which is exactly the fallback tgUsernamesFromRegistry wants.
 		scalar, _ := ch.GetUsername()
 		if vector := tgUsernamesFromRegistry(list, scalar); len(vector) > 0 {
-			ch.Flags.Unset(6)
-			ch.Username = ""
+			if primary := domain.ActiveUsername(list); primary != "" {
+				ch.SetUsername(primary)
+			} else {
+				ch.Flags.Unset(6)
+				ch.Username = ""
+			}
 			ch.SetUsernames(vector)
 		}
 	}
diff --git a/internal/rpc/username_notify_test.go b/internal/rpc/username_notify_test.go
index 51a998fc..0fdb5919 100644
--- a/internal/rpc/username_notify_test.go
+++ b/internal/rpc/username_notify_test.go
@@ -26,8 +26,8 @@ func TestNotifyPeerUsernamesChangedUserPushesPreloadedVector(t *testing.T) {
 	}
 	registry := newFakeUsernameRegistry()
 	registry.byPeer[domain.Peer{Type: domain.PeerTypeUser, ID: targetID}] = []domain.Username{
-		{Username: "owner_slot", Editable: true, Active: true},
-		{Username: "nft", Active: true, CollectibleID: 7},
+		{Username: "owner_slot", Editable: true, Active: true, SortOrder: 1},
+		{Username: "nft4", Active: true, SortOrder: 0, CollectibleID: 7},
 	}
 	sessions := &captureSessions{onlineUserIDs: []int64{targetID, viewerID}}
 	r := New(Config{}, Deps{Users: users, Usernames: registry, Sessions: sessions}, zap.NewNop(), clock.System)
@@ -42,11 +42,11 @@ func TestNotifyPeerUsernamesChangedUserPushesPreloadedVector(t *testing.T) {
 	}
 	updates := sessions.lastUserPush().(*tg.Updates)
 	user := updates.Users[0].(*tg.User)
-	if scalar, ok := user.GetUsername(); ok || scalar != "" {
-		t.Fatalf("pushed scalar username = %q (set %v), want absent", scalar, ok)
+	if scalar, ok := user.GetUsername(); !ok || scalar != "nft4" {
+		t.Fatalf("pushed scalar username = %q (set %v), want primary collectible nft4", scalar, ok)
 	}
 	vector, ok := user.GetUsernames()
-	if !ok || len(vector) != 2 || vector[1].Username != "nft" {
+	if !ok || len(vector) != 2 || vector[0].Username != "nft4" {
 		t.Fatalf("pushed username vector = %+v (set %v)", vector, ok)
 	}
 }
@@ -63,8 +63,8 @@ func TestNotifyPeerUsernamesChangedChannelPushesPreloadedVector(t *testing.T) {
 	}}
 	registry := newFakeUsernameRegistry()
 	registry.byPeer[domain.Peer{Type: domain.PeerTypeChannel, ID: channelID}] = []domain.Username{
-		{Username: "channel_slot", Editable: true, Active: true},
-		{Username: "collectible", Active: true, CollectibleID: 9},
+		{Username: "channel_slot", Editable: true, Active: true, SortOrder: 1},
+		{Username: "collectible", Active: true, SortOrder: 0, CollectibleID: 9},
 	}
 	sessions := &captureSessions{
 		onlineUserIDs:  []int64{ownerID, memberID},
@@ -84,11 +84,11 @@ func TestNotifyPeerUsernamesChangedChannelPushesPreloadedVector(t *testing.T) {
 	}
 	updates := sessions.lastUserPush().(*tg.Updates)
 	channel := updates.Chats[0].(*tg.Channel)
-	if scalar, ok := channel.GetUsername(); ok || scalar != "" {
-		t.Fatalf("pushed scalar username = %q (set %v), want absent", scalar, ok)
+	if scalar, ok := channel.GetUsername(); !ok || scalar != "collectible" {
+		t.Fatalf("pushed scalar username = %q (set %v), want primary collectible", scalar, ok)
 	}
 	vector, ok := channel.GetUsernames()
-	if !ok || len(vector) != 2 || vector[1].Username != "collectible" {
+	if !ok || len(vector) != 2 || vector[0].Username != "collectible" {
 		t.Fatalf("pushed username vector = %+v (set %v)", vector, ok)
 	}
 }
diff --git a/internal/store/collectible_username.go b/internal/store/collectible_username.go
index d453d47d..fe58d6a0 100644
--- a/internal/store/collectible_username.go
+++ b/internal/store/collectible_username.go
@@ -8,7 +8,8 @@ import (
 
 // UsernameRegistryStore reads a peer's full username list. The list is the
 // projection source for the TL usernames vector, so every caller sees the same
-// order the client will render: editable slot first, then collectibles.
+// stored order the client will render. Reorder may promote a collectible ahead
+// of the editable slot; the first active row is also the Layer 228 main scalar.
 type UsernameRegistryStore interface {
 	// PeerUsernames returns the peer's registry rows in projection order.
 	PeerUsernames(ctx context.Context, peer domain.Peer) ([]domain.Username, error)
diff --git a/internal/store/memory/channel_core.go b/internal/store/memory/channel_core.go
index 99f52406..b0214ff5 100644
--- a/internal/store/memory/channel_core.go
+++ b/internal/store/memory/channel_core.go
@@ -229,8 +229,15 @@ func (s *ChannelStore) GetChannelByID(_ context.Context, channelID int64) (domai
 	return cloneChannel(channel), nil
 }
 
-func publicPreviewableChannel(channel domain.Channel) bool {
-	return publicSearchableChannel(channel)
+func (s *ChannelStore) publicPreviewableChannelLocked(channel domain.Channel) bool {
+	hasActiveUsername := strings.TrimSpace(channel.Username) != ""
+	if !hasActiveUsername && s.usernameRegistry != nil {
+		hasActiveUsername = s.usernameRegistry.peerHasActiveCollectibleUsername(domain.Peer{
+			Type: domain.PeerTypeChannel,
+			ID:   channel.ID,
+		})
+	}
+	return publicSearchableChannel(channel) && hasActiveUsername
 }
 
 func minInt(a, b int) int {
diff --git a/internal/store/memory/channel_helpers.go b/internal/store/memory/channel_helpers.go
index 0d79ef0b..13eb2cd3 100644
--- a/internal/store/memory/channel_helpers.go
+++ b/internal/store/memory/channel_helpers.go
@@ -83,6 +83,13 @@ func (s *ChannelStore) SearchPublicChannels(_ context.Context, viewerUserID int6
 		return domain.PublicChannelSearchResult{}, nil
 	}
 	s.mu.RLock()
+	registry := s.usernameRegistry
+	s.mu.RUnlock()
+	var usernameMatches map[int64]int
+	if registry != nil {
+		usernameMatches = registry.activeUsernameMatches(query, domain.PeerTypeChannel)
+	}
+	s.mu.RLock()
 	defer s.mu.RUnlock()
 
 	type item struct {
@@ -92,6 +99,11 @@ func (s *ChannelStore) SearchPublicChannels(_ context.Context, viewerUserID int6
 	items := make([]item, 0, limit)
 	for channelID, channel := range s.channels {
 		rank, ok := publicChannelSearchRank(channel, query)
+		if usernameRank, matched := usernameMatches[channelID]; matched &&
+			!channel.Deleted && (channel.Broadcast || channel.Megagroup) &&
+			(!ok || usernameRank < rank) {
+			rank, ok = usernameRank, true
+		}
 		if !ok {
 			continue
 		}
@@ -426,7 +438,7 @@ func (s *ChannelStore) channelForViewerLocked(userID, channelID int64) (domain.C
 			return channel, syntheticMonoforumUserMember(channel, userID), true, nil
 		}
 	}
-	if !publicPreviewableChannel(channel) {
+	if !s.publicPreviewableChannelLocked(channel) {
 		return domain.Channel{}, domain.ChannelMember{}, false, domain.ErrChannelPrivate
 	}
 	return channel, publicPreviewMember(channel, userID, existing, found), true, nil
@@ -556,8 +568,7 @@ func recommendableChannel(channel domain.Channel) bool {
 
 func publicSearchableChannel(channel domain.Channel) bool {
 	return !channel.Deleted &&
-		(channel.Broadcast || channel.Megagroup) &&
-		strings.TrimSpace(channel.Username) != ""
+		(channel.Broadcast || channel.Megagroup)
 }
 
 func channelRoleOrder(role domain.ChannelMemberRole) int {
diff --git a/internal/store/memory/channel_members.go b/internal/store/memory/channel_members.go
index 14e63cc0..96be9cc3 100644
--- a/internal/store/memory/channel_members.go
+++ b/internal/store/memory/channel_members.go
@@ -902,7 +902,7 @@ func (s *ChannelStore) FilterChannelMessageAudienceIDs(_ context.Context, channe
 	if !ok || channel.Deleted {
 		return nil, nil
 	}
-	public := publicPreviewableChannel(channel)
+	public := s.publicPreviewableChannelLocked(channel)
 	members := s.members[channelID]
 	out := make([]int64, 0, len(userIDs))
 	seen := make(map[int64]struct{}, len(userIDs))
diff --git a/internal/store/memory/channel_message_history.go b/internal/store/memory/channel_message_history.go
index 5a29e800..c7993dd1 100644
--- a/internal/store/memory/channel_message_history.go
+++ b/internal/store/memory/channel_message_history.go
@@ -224,7 +224,7 @@ func (s *ChannelStore) SearchJoinedMessages(_ context.Context, viewerUserID int6
 		}
 		member, ok := s.members[channelID][viewerUserID]
 		joined := ok && member.Status == domain.ChannelMemberActive && !member.BannedRights.ViewMessages
-		publicPreview := req.AllowPublicPreview && publicPreviewableChannel(channel) &&
+		publicPreview := req.AllowPublicPreview && s.publicPreviewableChannelLocked(channel) &&
 			(!ok || member.Status != domain.ChannelMemberKicked && !member.BannedRights.ViewMessages)
 		if !joined && !publicPreview {
 			continue
diff --git a/internal/store/memory/channel_settings.go b/internal/store/memory/channel_settings.go
index 89fb99a7..0122fc77 100644
--- a/internal/store/memory/channel_settings.go
+++ b/internal/store/memory/channel_settings.go
@@ -139,7 +139,7 @@ func (s *ChannelStore) CheckUsername(_ context.Context, userID, channelID int64,
 	return true, nil
 }
 
-func (s *ChannelStore) UpdateUsername(_ context.Context, req domain.UpdateChannelUsernameRequest) (domain.Channel, error) {
+func (s *ChannelStore) UpdateUsername(ctx context.Context, req domain.UpdateChannelUsernameRequest) (domain.Channel, error) {
 	if req.UserID == 0 || req.ChannelID == 0 {
 		return domain.Channel{}, domain.ErrChannelInvalid
 	}
@@ -168,6 +168,11 @@ func (s *ChannelStore) UpdateUsername(_ context.Context, req domain.UpdateChanne
 			}
 		}
 	}
+	if s.usernameRegistry != nil {
+		if _, err := s.usernameRegistry.SetEditableUsername(ctx, domain.Peer{Type: domain.PeerTypeChannel, ID: req.ChannelID}, username); err != nil {
+			return domain.Channel{}, err
+		}
+	}
 	prevUsername := channel.Username
 	channel.Username = username
 	s.channels[req.ChannelID] = channel
@@ -311,16 +316,27 @@ func (s *ChannelStore) ResolvePublicChannelUsername(_ context.Context, viewerUse
 		return domain.Channel{}, false, nil
 	}
 	s.mu.RLock()
-	defer s.mu.RUnlock()
-
+	registry := s.usernameRegistry
 	for _, channel := range s.channels {
 		if !publicSearchableChannel(channel) {
 			continue
 		}
 		if strings.ToLower(channel.Username) == username {
+			s.mu.RUnlock()
 			return cloneChannel(channel), true, nil
 		}
 	}
+	s.mu.RUnlock()
+	if registry != nil {
+		if peer, ok := registry.activeUsernamePeer(username, domain.PeerTypeChannel); ok {
+			s.mu.RLock()
+			channel, found := s.channels[peer.ID]
+			s.mu.RUnlock()
+			if found && !channel.Deleted && (channel.Broadcast || channel.Megagroup) {
+				return cloneChannel(channel), true, nil
+			}
+		}
+	}
 	return domain.Channel{}, false, nil
 }
 
diff --git a/internal/store/memory/channel_store.go b/internal/store/memory/channel_store.go
index c9a38cf5..5978f3c3 100644
--- a/internal/store/memory/channel_store.go
+++ b/internal/store/memory/channel_store.go
@@ -101,7 +101,8 @@ type ChannelStore struct {
 	// topicReads 是 per-(channel,user,topic) 已读水位（forum 话题独立已读，不碰频道级 member 水位）。
 	topicReads map[int64]map[int64]map[int]memoryTopicRead
 	// polls 是共享 poll 权威（与 MessageStore 同一实例）；nil 时 poll 链路按未接入处理。
-	polls *PollStore
+	polls            *PollStore
+	usernameRegistry *CollectibleUsernameStore
 }
 
 // AttachPollStore 注入共享 poll 权威。
@@ -109,6 +110,14 @@ func (s *ChannelStore) AttachPollStore(polls *PollStore) {
 	s.polls = polls
 }
 
+// AttachUsernameRegistry gives the memory backend the same global username
+// index the PostgreSQL stores share through peer_usernames.
+func (s *ChannelStore) AttachUsernameRegistry(registry *CollectibleUsernameStore) {
+	s.mu.Lock()
+	s.usernameRegistry = registry
+	s.mu.Unlock()
+}
+
 // NewChannelStore creates an in-memory ChannelStore.
 func NewChannelStore() *ChannelStore {
 	return &ChannelStore{
diff --git a/internal/store/memory/collectible_username.go b/internal/store/memory/collectible_username.go
index 219a42b9..6f0052c8 100644
--- a/internal/store/memory/collectible_username.go
+++ b/internal/store/memory/collectible_username.go
@@ -161,6 +161,61 @@ func (s *CollectibleUsernameStore) PeerUsernamesBatch(_ context.Context, peers [
 	return out, nil
 }
 
+// activeUsernamePeer resolves an active registry name for the memory user and
+// channel stores. Keeping lookup on the same registry that owns toggle/reorder
+// state prevents the test backend from silently falling back to scalar-only
+// behavior.
+func (s *CollectibleUsernameStore) activeUsernamePeer(username string, peerType domain.PeerType) (domain.Peer, bool) {
+	key := strings.ToLower(domain.NormalizeUsername(username))
+	if key == "" {
+		return domain.Peer{}, false
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	entry, ok := s.registry[key]
+	if !ok || !entry.row.Active || entry.peer.Type != peerType {
+		return domain.Peer{}, false
+	}
+	return entry.peer, true
+}
+
+// activeUsernameMatches returns the best username rank for each peer: exact
+// matches precede prefix matches. Inactive rows stay occupied in the registry
+// but are deliberately absent from client search.
+func (s *CollectibleUsernameStore) activeUsernameMatches(query string, peerType domain.PeerType) map[int64]int {
+	query = strings.ToLower(domain.NormalizeUsername(query))
+	if query == "" {
+		return nil
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	out := make(map[int64]int)
+	for username, entry := range s.registry {
+		if !entry.row.Active || entry.peer.Type != peerType || !strings.HasPrefix(username, query) {
+			continue
+		}
+		rank := 1
+		if username == query {
+			rank = 0
+		}
+		if current, ok := out[entry.peer.ID]; !ok || rank < current {
+			out[entry.peer.ID] = rank
+		}
+	}
+	return out
+}
+
+func (s *CollectibleUsernameStore) peerHasActiveCollectibleUsername(peer domain.Peer) bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for _, entry := range s.registry {
+		if entry.peer == peer && entry.row.Active && !entry.row.Editable {
+			return true
+		}
+	}
+	return false
+}
+
 // SetUsernameActive toggles one collectible row. The domain validator owns the
 // rules: the editable slot is off limits and a peer that holds usernames must
 // keep at least one active.
diff --git a/internal/store/memory/community.go b/internal/store/memory/community.go
index a6635416..1d49abf8 100644
--- a/internal/store/memory/community.go
+++ b/internal/store/memory/community.go
@@ -112,7 +112,7 @@ func (s *CommunityStore) viewLocked(userID, id int64) (domain.CommunityView, err
 			cm, ok := s.channels.members[l.Peer.ID][userID]
 			joined = ok && cm.Status == domain.ChannelMemberActive
 			if channel, ok := s.channels.channels[l.Peer.ID]; ok {
-				inherentlyViewable = publicPreviewableChannel(channel)
+				inherentlyViewable = s.channels.publicPreviewableChannelLocked(channel)
 			}
 			s.channels.mu.RUnlock()
 		} else if l.Peer.Type == domain.PeerTypeUser && s.dialogs != nil {
diff --git a/internal/store/memory/users.go b/internal/store/memory/users.go
index cfa5f8b7..8caff7e3 100644
--- a/internal/store/memory/users.go
+++ b/internal/store/memory/users.go
@@ -11,9 +11,10 @@ import (
 
 // UserStore 是 store.UserStore 的内存实现。ID 与 PG identity 使用同一业务起点。
 type UserStore struct {
-	mu     sync.RWMutex
-	byID   map[int64]domain.User
-	nextID int64
+	mu               sync.RWMutex
+	byID             map[int64]domain.User
+	nextID           int64
+	usernameRegistry *CollectibleUsernameStore
 }
 
 // NewUserStore 创建内存 UserStore。内置系统账号（777000 / BotFather / Stickers / ChatBot）
@@ -28,6 +29,14 @@ func NewUserStore() *UserStore {
 	return s
 }
 
+// AttachUsernameRegistry gives the memory backend the same global username
+// index the PostgreSQL stores share through peer_usernames.
+func (s *UserStore) AttachUsernameRegistry(registry *CollectibleUsernameStore) {
+	s.mu.Lock()
+	s.usernameRegistry = registry
+	s.mu.Unlock()
+}
+
 func (s *UserStore) ByID(_ context.Context, id int64) (domain.User, bool, error) {
 	s.mu.RLock()
 	u, ok := s.byID[id]
@@ -104,18 +113,25 @@ func (s *UserStore) ByPhones(_ context.Context, phones []string) ([]domain.User,
 	return out, nil
 }
 
-func (s *UserStore) ByUsername(_ context.Context, username string) (domain.User, bool, error) {
+func (s *UserStore) ByUsername(ctx context.Context, username string) (domain.User, bool, error) {
 	username = strings.ToLower(strings.TrimSpace(strings.TrimPrefix(username, "@")))
 	if username == "" {
 		return domain.User{}, false, nil
 	}
 	s.mu.RLock()
-	defer s.mu.RUnlock()
+	registry := s.usernameRegistry
 	for _, u := range s.byID {
 		if !u.Deleted && strings.ToLower(u.Username) == username {
+			s.mu.RUnlock()
 			return u, true, nil
 		}
 	}
+	s.mu.RUnlock()
+	if registry != nil {
+		if peer, ok := registry.activeUsernamePeer(username, domain.PeerTypeUser); ok {
+			return s.ByID(ctx, peer.ID)
+		}
+	}
 	return domain.User{}, false, nil
 }
 
@@ -144,13 +160,21 @@ func (s *UserStore) Search(_ context.Context, currentUserID int64, query, phoneQ
 		return domain.UserSearchResult{}, nil
 	}
 	s.mu.RLock()
+	registry := s.usernameRegistry
+	s.mu.RUnlock()
+	var usernameMatches map[int64]int
+	if registry != nil {
+		usernameMatches = registry.activeUsernameMatches(query, domain.PeerTypeUser)
+	}
+	s.mu.RLock()
 	defer s.mu.RUnlock()
 	users := make([]domain.User, 0)
 	for _, u := range s.byID {
 		if u.ID == currentUserID || u.Deleted {
 			continue
 		}
-		if userMatchesSearch(u, query, phoneQuery) {
+		_, usernameMatch := usernameMatches[u.ID]
+		if usernameMatch || userMatchesSearch(u, query, phoneQuery) {
 			users = append(users, u)
 		}
 	}
@@ -163,7 +187,7 @@ func (s *UserStore) Search(_ context.Context, currentUserID int64, query, phoneQ
 	return domain.UserSearchResult{Results: users}, nil
 }
 
-func (s *UserStore) UpdateUsername(_ context.Context, userID int64, username string) (domain.User, error) {
+func (s *UserStore) UpdateUsername(ctx context.Context, userID int64, username string) (domain.User, error) {
 	username = strings.TrimSpace(strings.TrimPrefix(username, "@"))
 	usernameLower := strings.ToLower(username)
 	s.mu.Lock()
@@ -179,6 +203,11 @@ func (s *UserStore) UpdateUsername(_ context.Context, userID int64, username str
 			}
 		}
 	}
+	if s.usernameRegistry != nil {
+		if _, err := s.usernameRegistry.SetEditableUsername(ctx, domain.Peer{Type: domain.PeerTypeUser, ID: userID}, username); err != nil {
+			return domain.User{}, err
+		}
+	}
 	u.Username = username
 	s.byID[userID] = u
 	return u, nil
diff --git a/internal/store/postgres/channel_core.go b/internal/store/postgres/channel_core.go
index 85e1cae6..5458e3e9 100644
--- a/internal/store/postgres/channel_core.go
+++ b/internal/store/postgres/channel_core.go
@@ -395,6 +395,10 @@ WHERE c.id = ANY($2::bigint[]) AND NOT c.deleted`, viewerUserID, ids)
 	if err != nil {
 		return nil, err
 	}
+	publicUsernameIDs, err := activeCollectibleUsernamePeerIDs(ctx, s.db, peerUsernameTypeChannel, remaining)
+	if err != nil {
+		return nil, err
+	}
 	for _, channel := range channels {
 		if member, ok := linkedGuests[channel.ID]; ok {
 			views[channel.ID] = domain.ChannelView{
@@ -427,7 +431,8 @@ WHERE c.id = ANY($2::bigint[]) AND NOT c.deleted`, viewerUserID, ids)
 				continue
 			}
 		}
-		if !publicPreviewableChannel(channel) {
+		_, hasActiveUsername := publicUsernameIDs[channel.ID]
+		if !publicPreviewableChannel(channel, hasActiveUsername) {
 			continue
 		}
 		existing, found := previewMembers[channel.ID]
@@ -514,10 +519,10 @@ func finishChannelScan(ch *domain.Channel, rights, reactionPolicy string, wallpa
 	}
 }
 
-func publicPreviewableChannel(channel domain.Channel) bool {
+func publicPreviewableChannel(channel domain.Channel, hasActiveUsername bool) bool {
 	return !channel.Deleted &&
 		(channel.Broadcast || channel.Megagroup) &&
-		strings.TrimSpace(channel.Username) != ""
+		(strings.TrimSpace(channel.Username) != "" || hasActiveUsername)
 }
 
 func refreshChannelCountsTx(ctx context.Context, tx pgx.Tx, channel domain.Channel) (domain.Channel, error) {
diff --git a/internal/store/postgres/channel_helpers.go b/internal/store/postgres/channel_helpers.go
index 87c03e93..f70f6ea6 100644
--- a/internal/store/postgres/channel_helpers.go
+++ b/internal/store/postgres/channel_helpers.go
@@ -150,11 +150,28 @@ func (s *ChannelStore) SearchPublicChannels(ctx context.Context, viewerUserID in
 	queryPrefix := escapeLike(queryLower) + "%"
 	queryLike := "%" + escapeLike(queryLower) + "%"
 	rows, err := s.db.Query(ctx, `
+WITH username_matches AS (
+  SELECT
+    peer_id,
+    MIN(CASE
+      WHEN username_lower = $2 THEN 0
+      ELSE 1
+    END) AS rank
+  FROM peer_usernames
+  WHERE peer_type = 'channel'
+    AND active
+    AND collectible_id IS NOT NULL
+    AND (
+      username_lower = $2
+      OR username_lower LIKE $3 ESCAPE '\'
+    )
+  GROUP BY peer_id
+)
 SELECT `+channelColumns+`
 FROM channels c
+LEFT JOIN username_matches um ON um.peer_id = c.id
 WHERE NOT c.deleted
   AND (c.broadcast OR c.megagroup)
-  AND COALESCE(c.username, '') <> ''
   AND NOT EXISTS (
     SELECT 1
     FROM channel_members m
@@ -163,15 +180,16 @@ WHERE NOT c.deleted
       AND m.status = 'active'
   )
   AND (
-    lower(c.username) = $2
+    um.peer_id IS NOT NULL
+    OR lower(c.username) = $2
     OR lower(c.username) LIKE $3 ESCAPE '\'
     OR lower(c.title) LIKE $3 ESCAPE '\'
     OR lower(c.username) LIKE $4 ESCAPE '\'
     OR lower(c.title) LIKE $4 ESCAPE '\'
   )
 ORDER BY CASE
-    WHEN lower(c.username) = $2 THEN 0
-    WHEN lower(c.username) LIKE $3 ESCAPE '\' THEN 1
+    WHEN um.rank = 0 OR lower(c.username) = $2 THEN 0
+    WHEN um.rank = 1 OR lower(c.username) LIKE $3 ESCAPE '\' THEN 1
     WHEN lower(c.username) LIKE $4 ESCAPE '\' THEN 2
     WHEN lower(c.title) LIKE $3 ESCAPE '\' THEN 3
     ELSE 4
@@ -421,7 +439,12 @@ func (s *ChannelStore) getChannelForViewer(ctx context.Context, db sqlcgen.DBTX,
 			return ch, syntheticMonoforumUserMember(ch, viewerUserID), true, nil
 		}
 	}
-	if !publicPreviewableChannel(ch) {
+	publicUsernameIDs, err := activeCollectibleUsernamePeerIDs(ctx, db, peerUsernameTypeChannel, []int64{ch.ID})
+	if err != nil {
+		return domain.Channel{}, domain.ChannelMember{}, false, err
+	}
+	_, hasActiveUsername := publicUsernameIDs[ch.ID]
+	if !publicPreviewableChannel(ch, hasActiveUsername) {
 		return domain.Channel{}, domain.ChannelMember{}, false, domain.ErrChannelPrivate
 	}
 	member, err = s.getPublicPreviewMember(ctx, db, viewerUserID, ch)
diff --git a/internal/store/postgres/channel_settings.go b/internal/store/postgres/channel_settings.go
index ba55ceba..548837ab 100644
--- a/internal/store/postgres/channel_settings.go
+++ b/internal/store/postgres/channel_settings.go
@@ -510,6 +510,9 @@ func (s *ChannelStore) ResolvePublicChannelUsername(ctx context.Context, viewerU
 	if !found || owner.peerType != peerUsernameTypeChannel {
 		return domain.Channel{}, false, nil
 	}
+	if !owner.active {
+		return domain.Channel{}, false, nil
+	}
 	ch, err := getChannelByID(ctx, s.db, owner.peerID)
 	if err != nil {
 		if errors.Is(err, domain.ErrChannelInvalid) {
@@ -517,7 +520,7 @@ func (s *ChannelStore) ResolvePublicChannelUsername(ctx context.Context, viewerU
 		}
 		return domain.Channel{}, false, fmt.Errorf("resolve public channel username channel: %w", err)
 	}
-	if !publicPreviewableChannel(ch) {
+	if !publicPreviewableChannel(ch, true) {
 		return domain.Channel{}, false, nil
 	}
 	// A collectible row is authoritative for its own name: the channel's scalar
@@ -527,9 +530,6 @@ func (s *ChannelStore) ResolvePublicChannelUsername(ctx context.Context, viewerU
 	if !owner.collectible && !strings.EqualFold(ch.Username, usernameLower) {
 		return domain.Channel{}, false, nil
 	}
-	if owner.collectible && !owner.active {
-		return domain.Channel{}, false, nil
-	}
 	return ch, true, nil
 }
 
diff --git a/internal/store/postgres/collectible_username_integration_test.go b/internal/store/postgres/collectible_username_integration_test.go
index 4c2663cb..de8c3fc8 100644
--- a/internal/store/postgres/collectible_username_integration_test.go
+++ b/internal/store/postgres/collectible_username_integration_test.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 	"testing"
 	"time"
 
@@ -90,6 +91,164 @@ func registryRows(t *testing.T, pool *pgxpool.Pool, peer domain.Peer) []domain.U
 	return list
 }
 
+func TestCollectibleUsernameResolveAndSearchUseActiveRegistry(t *testing.T) {
+	pool := testPool(t)
+	ctx := context.Background()
+	seed := time.Now().UnixNano() % 1_000_000
+	viewer := collectibleTestUser(t, pool, 3_100_000_000+seed, "")
+	userPeer := collectibleTestUser(t, pool, 3_200_000_000+seed, "")
+	userEditable := fmt.Sprintf("uedit%d", seed)
+	userCollectible := fmt.Sprintf("unft%d", seed)
+	setEditableUsername(t, pool, userPeer, userEditable)
+	cleanupCollectible(t, pool, lowerASCII(userCollectible))
+
+	registry := NewCollectibleUsernameStore(pool)
+	if _, created, err := registry.MintCollectibleUsername(ctx, mintRequest(userCollectible, userPeer, "")); err != nil || !created {
+		t.Fatalf("mint user collectible: created=%v err=%v", created, err)
+	}
+	users := NewUserStore(pool)
+	resolvedUser, found, err := users.ByUsername(ctx, userCollectible)
+	if err != nil || !found || resolvedUser.ID != userPeer.ID {
+		t.Fatalf("resolve user collectible = %+v found=%v err=%v", resolvedUser, found, err)
+	}
+	userSearch, err := users.Search(ctx, viewer.ID, userCollectible, "", 10)
+	if err != nil || len(userSearch.Results) != 1 || userSearch.Results[0].ID != userPeer.ID {
+		t.Fatalf("search user collectible = %+v err=%v", userSearch, err)
+	}
+	if changed, err := registry.SetUsernameActive(ctx, userPeer, userCollectible, false); err != nil || !changed {
+		t.Fatalf("deactivate user collectible: changed=%v err=%v", changed, err)
+	}
+	if _, found, err := users.ByUsername(ctx, userCollectible); err != nil || found {
+		t.Fatalf("resolve inactive user collectible found=%v err=%v", found, err)
+	}
+	if hidden, err := users.Search(ctx, viewer.ID, userCollectible, "", 10); err != nil || len(hidden.Results)+len(hidden.MyResults) != 0 {
+		t.Fatalf("search inactive user collectible = %+v err=%v", hidden, err)
+	}
+
+	channels := NewChannelStore(pool)
+	created, err := channels.CreateChannel(ctx, domain.CreateChannelRequest{
+		CreatorUserID: userPeer.ID,
+		Title:         "Unrelated collectible channel",
+		Broadcast:     true,
+		Date:          int(time.Now().Unix()),
+	})
+	if err != nil {
+		t.Fatalf("create channel: %v", err)
+	}
+	channelPeer := domain.Peer{Type: domain.PeerTypeChannel, ID: created.Channel.ID}
+	t.Cleanup(func() {
+		_, _ = pool.Exec(context.Background(), `DELETE FROM channels WHERE id = $1`, channelPeer.ID)
+	})
+	channelEditable := fmt.Sprintf("cedit%d", seed)
+	if _, err := channels.UpdateUsername(ctx, domain.UpdateChannelUsernameRequest{
+		UserID:    userPeer.ID,
+		ChannelID: channelPeer.ID,
+		Username:  channelEditable,
+	}); err != nil {
+		t.Fatalf("set channel editable username: %v", err)
+	}
+	channelCollectible := fmt.Sprintf("cnft%d", seed)
+	cleanupCollectible(t, pool, lowerASCII(channelCollectible))
+	if _, created, err := registry.MintCollectibleUsername(ctx, mintRequest(channelCollectible, channelPeer, "")); err != nil || !created {
+		t.Fatalf("mint channel collectible: created=%v err=%v", created, err)
+	}
+	resolvedChannel, found, err := channels.ResolvePublicChannelUsername(ctx, viewer.ID, channelCollectible)
+	if err != nil || !found || resolvedChannel.ID != channelPeer.ID {
+		t.Fatalf("resolve channel collectible = %+v found=%v err=%v", resolvedChannel, found, err)
+	}
+	channelSearch, err := channels.SearchPublicChannels(ctx, viewer.ID, channelCollectible, 10)
+	if err != nil || len(channelSearch.Results) != 1 || channelSearch.Results[0].ID != channelPeer.ID {
+		t.Fatalf("search channel collectible = %+v err=%v", channelSearch, err)
+	}
+	if _, err := channels.UpdateUsername(ctx, domain.UpdateChannelUsernameRequest{
+		UserID:    userPeer.ID,
+		ChannelID: channelPeer.ID,
+		Username:  "",
+	}); err != nil {
+		t.Fatalf("clear channel editable username: %v", err)
+	}
+	if nftOnly, found, err := channels.ResolvePublicChannelUsername(ctx, viewer.ID, channelCollectible); err != nil || !found || nftOnly.ID != channelPeer.ID {
+		t.Fatalf("resolve NFT-only channel = %+v found=%v err=%v", nftOnly, found, err)
+	}
+	if view, err := channels.GetChannel(ctx, viewer.ID, channelPeer.ID); err != nil || view.Channel.ID != channelPeer.ID {
+		t.Fatalf("preview NFT-only channel = %+v err=%v", view, err)
+	}
+	if _, err := channels.UpdateUsername(ctx, domain.UpdateChannelUsernameRequest{
+		UserID:    userPeer.ID,
+		ChannelID: channelPeer.ID,
+		Username:  channelEditable,
+	}); err != nil {
+		t.Fatalf("restore channel editable username: %v", err)
+	}
+	if changed, err := registry.SetUsernameActive(ctx, channelPeer, channelCollectible, false); err != nil || !changed {
+		t.Fatalf("deactivate channel collectible: changed=%v err=%v", changed, err)
+	}
+	if _, found, err := channels.ResolvePublicChannelUsername(ctx, viewer.ID, channelCollectible); err != nil || found {
+		t.Fatalf("resolve inactive channel collectible found=%v err=%v", found, err)
+	}
+	if hidden, err := channels.SearchPublicChannels(ctx, viewer.ID, channelCollectible, 10); err != nil || len(hidden.Results) != 0 {
+		t.Fatalf("search inactive channel collectible = %+v err=%v", hidden, err)
+	}
+}
+
+func TestCollectibleUsernameSearchPrefixUsesActiveRegistryIndex(t *testing.T) {
+	pool := testPool(t)
+	ctx := context.Background()
+	tx, err := pool.Begin(ctx)
+	if err != nil {
+		t.Fatalf("begin: %v", err)
+	}
+	defer func() { _ = tx.Rollback(ctx) }()
+	if _, err := tx.Exec(ctx, `
+WITH names AS (
+  SELECT
+    CASE WHEN n = 1 THEN 'nftplanfixture' ELSE 'otherplanfixture' || n::text END AS username,
+    9100000000 + n AS owner_peer_id
+  FROM generate_series(1, 5000) AS n
+),
+assets AS (
+  INSERT INTO collectible_usernames (
+    username, username_lower, status, owner_peer_type, owner_peer_id,
+    purchase_date, currency, amount,
+    original_owner_peer_type, original_owner_peer_id,
+    created_at, updated_at
+  )
+  SELECT
+    username, username, 'owned', 'user', owner_peer_id,
+    now(), 'XTR', 1,
+    'user', owner_peer_id,
+    now(), now()
+  FROM names
+  RETURNING id, username, username_lower, owner_peer_id
+)
+INSERT INTO peer_usernames (
+  username_lower, username, peer_type, peer_id,
+  active, editable, sort_order, collectible_id
+)
+SELECT
+  username_lower, username, 'user', owner_peer_id,
+  true, false, 0, id
+FROM assets`); err != nil {
+		t.Fatalf("seed username plan fixture: %v", err)
+	}
+	if _, err := tx.Exec(ctx, "ANALYZE peer_usernames"); err != nil {
+		t.Fatalf("analyze username plan fixture: %v", err)
+	}
+	if _, err := tx.Exec(ctx, "SET LOCAL enable_seqscan = off"); err != nil {
+		t.Fatalf("disable seqscan: %v", err)
+	}
+	plan := explainText(t, ctx, tx, `
+SELECT peer_id
+FROM peer_usernames
+WHERE peer_type = 'user'
+  AND active
+  AND collectible_id IS NOT NULL
+  AND username_lower LIKE $1 || '%' ESCAPE '\'`, "nft")
+	if !strings.Contains(plan, "peer_usernames_active_search_idx") {
+		t.Fatalf("active username prefix plan = %s, want peer_usernames_active_search_idx", plan)
+	}
+}
+
 // TestCollectibleUsernameMintIntoVault covers a vault mint: the asset exists, the
 // name is not projected into any peer's registry, and the provenance log records
 // the mint.
diff --git a/internal/store/postgres/peer_username.go b/internal/store/postgres/peer_username.go
index 1f311a4c..5a00a838 100644
--- a/internal/store/postgres/peer_username.go
+++ b/internal/store/postgres/peer_username.go
@@ -69,6 +69,39 @@ func peerUsernameAvailable(ctx context.Context, db sqlcgen.DBTX, usernameLower,
 	return owner.matches(peerType, peerID), nil
 }
 
+// activeCollectibleUsernamePeerIDs returns the requested peers that own at
+// least one active collectible username. Editable registry rows are excluded:
+// their scalar users.username/channels.username value is the cross-check that
+// prevents a stale registry row from making a private peer public.
+func activeCollectibleUsernamePeerIDs(ctx context.Context, db sqlcgen.DBTX, peerType string, peerIDs []int64) (map[int64]struct{}, error) {
+	out := make(map[int64]struct{})
+	if len(peerIDs) == 0 {
+		return out, nil
+	}
+	rows, err := db.Query(ctx, `
+SELECT DISTINCT peer_id
+FROM peer_usernames
+WHERE peer_type = $1
+  AND active
+  AND collectible_id IS NOT NULL
+  AND peer_id = ANY($2::bigint[])`, peerType, peerIDs)
+	if err != nil {
+		return nil, fmt.Errorf("list peers with active usernames: %w", err)
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var peerID int64
+		if err := rows.Scan(&peerID); err != nil {
+			return nil, fmt.Errorf("scan peer with active username: %w", err)
+		}
+		out[peerID] = struct{}{}
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("list peers with active usernames: %w", err)
+	}
+	return out, nil
+}
+
 // replacePeerUsernameTx rewrites the peer's editable username slot. username is
 // the display form (original case) and usernameLower its registry key; an empty
 // pair clears the slot.
diff --git a/internal/store/postgres/queries/user.sql b/internal/store/postgres/queries/user.sql
index c0c170d5..72c6af8e 100644
--- a/internal/store/postgres/queries/user.sql
+++ b/internal/store/postgres/queries/user.sql
@@ -20,7 +20,18 @@ ORDER BY id;
 SELECT * FROM users WHERE lower(username) = lower($1) AND username <> '' AND deleted_at IS NULL;
 
 -- name: SearchUsers :many
-WITH matched AS (
+WITH username_matches AS (
+  SELECT
+    peer_id,
+    bool_or(username_lower = sqlc.arg(query_lower)::text) AS exact
+  FROM peer_usernames
+  WHERE peer_type = 'user'
+    AND active
+    AND collectible_id IS NOT NULL
+    AND username_lower LIKE sqlc.arg(query_like)::text || '%' ESCAPE '\'
+  GROUP BY peer_id
+),
+matched AS (
   SELECT
     u.id,
     u.access_hash,
@@ -51,7 +62,7 @@ WITH matched AS (
     COALESCE(c.mutual, false)::boolean AS mutual,
     CASE
       WHEN sqlc.arg(phone_query)::text <> '' AND u.phone = sqlc.arg(phone_query)::text THEN 0
-      WHEN lower(u.username) = sqlc.arg(query_lower)::text THEN 1
+      WHEN COALESCE(um.exact, false) OR lower(u.username) = sqlc.arg(query_lower)::text THEN 1
       WHEN lower(COALESCE(NULLIF(c.contact_first_name, ''), u.first_name)) = sqlc.arg(query_lower)::text THEN 2
       WHEN lower(u.first_name) = sqlc.arg(query_lower)::text THEN 3
       WHEN c.contact_user_id IS NOT NULL THEN 4
@@ -59,11 +70,13 @@ WITH matched AS (
     END AS rank
   FROM users u
   LEFT JOIN contacts c ON c.user_id = sqlc.arg(current_user_id)::bigint AND c.contact_user_id = u.id
+  LEFT JOIN username_matches um ON um.peer_id = u.id
   WHERE u.id <> sqlc.arg(current_user_id)::bigint
     AND u.deleted_at IS NULL
     AND sqlc.arg(query_lower)::text <> ''
     AND (
       (sqlc.arg(phone_query)::text <> '' AND u.phone LIKE sqlc.arg(phone_query)::text || '%')
+      OR um.peer_id IS NOT NULL
       OR lower(u.username) LIKE sqlc.arg(query_like)::text || '%' ESCAPE '\'
       OR lower(u.first_name) LIKE '%' || sqlc.arg(query_like)::text || '%' ESCAPE '\'
       OR lower(u.last_name) LIKE '%' || sqlc.arg(query_like)::text || '%' ESCAPE '\'
diff --git a/internal/store/postgres/sqlcgen/user.sql.go b/internal/store/postgres/sqlcgen/user.sql.go
index 52411e35..2d03c6dd 100644
--- a/internal/store/postgres/sqlcgen/user.sql.go
+++ b/internal/store/postgres/sqlcgen/user.sql.go
@@ -364,7 +364,18 @@ func (q *Queries) GetUsersByPhones(ctx context.Context, phones []string) ([]User
 }
 
 const searchUsers = `-- name: SearchUsers :many
-WITH matched AS (
+WITH username_matches AS (
+  SELECT
+    peer_id,
+    bool_or(username_lower = $2::text) AS exact
+  FROM peer_usernames
+  WHERE peer_type = 'user'
+    AND active
+    AND collectible_id IS NOT NULL
+    AND username_lower LIKE $3::text || '%' ESCAPE '\'
+  GROUP BY peer_id
+),
+matched AS (
   SELECT
     u.id,
     u.access_hash,
@@ -394,27 +405,29 @@ WITH matched AS (
     (c.contact_user_id IS NOT NULL)::boolean AS contact,
     COALESCE(c.mutual, false)::boolean AS mutual,
     CASE
-      WHEN $2::text <> '' AND u.phone = $2::text THEN 0
-      WHEN lower(u.username) = $3::text THEN 1
-      WHEN lower(COALESCE(NULLIF(c.contact_first_name, ''), u.first_name)) = $3::text THEN 2
-      WHEN lower(u.first_name) = $3::text THEN 3
+      WHEN $4::text <> '' AND u.phone = $4::text THEN 0
+      WHEN COALESCE(um.exact, false) OR lower(u.username) = $2::text THEN 1
+      WHEN lower(COALESCE(NULLIF(c.contact_first_name, ''), u.first_name)) = $2::text THEN 2
+      WHEN lower(u.first_name) = $2::text THEN 3
       WHEN c.contact_user_id IS NOT NULL THEN 4
       ELSE 5
     END AS rank
   FROM users u
-  LEFT JOIN contacts c ON c.user_id = $4::bigint AND c.contact_user_id = u.id
-  WHERE u.id <> $4::bigint
+  LEFT JOIN contacts c ON c.user_id = $5::bigint AND c.contact_user_id = u.id
+  LEFT JOIN username_matches um ON um.peer_id = u.id
+  WHERE u.id <> $5::bigint
     AND u.deleted_at IS NULL
-    AND $3::text <> ''
+    AND $2::text <> ''
     AND (
-      ($2::text <> '' AND u.phone LIKE $2::text || '%')
-      OR lower(u.username) LIKE $5::text || '%' ESCAPE '\'
-      OR lower(u.first_name) LIKE '%' || $5::text || '%' ESCAPE '\'
-      OR lower(u.last_name) LIKE '%' || $5::text || '%' ESCAPE '\'
-      OR lower(trim(u.first_name || ' ' || u.last_name)) LIKE '%' || $5::text || '%' ESCAPE '\'
-      OR lower(c.contact_first_name) LIKE '%' || $5::text || '%' ESCAPE '\'
-      OR lower(c.contact_last_name) LIKE '%' || $5::text || '%' ESCAPE '\'
-      OR lower(trim(c.contact_first_name || ' ' || c.contact_last_name)) LIKE '%' || $5::text || '%' ESCAPE '\'
+      ($4::text <> '' AND u.phone LIKE $4::text || '%')
+      OR um.peer_id IS NOT NULL
+      OR lower(u.username) LIKE $3::text || '%' ESCAPE '\'
+      OR lower(u.first_name) LIKE '%' || $3::text || '%' ESCAPE '\'
+      OR lower(u.last_name) LIKE '%' || $3::text || '%' ESCAPE '\'
+      OR lower(trim(u.first_name || ' ' || u.last_name)) LIKE '%' || $3::text || '%' ESCAPE '\'
+      OR lower(c.contact_first_name) LIKE '%' || $3::text || '%' ESCAPE '\'
+      OR lower(c.contact_last_name) LIKE '%' || $3::text || '%' ESCAPE '\'
+      OR lower(trim(c.contact_first_name || ' ' || c.contact_last_name)) LIKE '%' || $3::text || '%' ESCAPE '\'
     )
 )
 SELECT
@@ -452,10 +465,10 @@ LIMIT $1
 
 type SearchUsersParams struct {
 	LimitCount    int32
-	PhoneQuery    string
 	QueryLower    string
-	CurrentUserID int64
 	QueryLike     string
+	PhoneQuery    string
+	CurrentUserID int64
 }
 
 type SearchUsersRow struct {
@@ -491,10 +504,10 @@ type SearchUsersRow struct {
 func (q *Queries) SearchUsers(ctx context.Context, arg SearchUsersParams) ([]SearchUsersRow, error) {
 	rows, err := q.db.Query(ctx, searchUsers,
 		arg.LimitCount,
-		arg.PhoneQuery,
 		arg.QueryLower,
-		arg.CurrentUserID,
 		arg.QueryLike,
+		arg.PhoneQuery,
+		arg.CurrentUserID,
 	)
 	if err != nil {
 		return nil, err
diff --git a/internal/web/server.go b/internal/web/server.go
index 2b379c05..f3d19d22 100644
--- a/internal/web/server.go
+++ b/internal/web/server.go
@@ -703,15 +703,20 @@ func (h *handler) resolvePublicPeer(ctx context.Context, username string) (publi
 }
 
 func (h *handler) publicUserPeer(ctx context.Context, requested string, u domain.User) (publicPeer, bool, error) {
-	if u.ID == 0 || !strings.EqualFold(strings.TrimSpace(u.Username), requested) || !validUsernamePath(u.Username) {
+	requested = domain.NormalizeUsername(requested)
+	if u.ID == 0 || !validUsernamePath(requested) {
 		return publicPeer{}, false, fmt.Errorf("user username lookup returned invalid owner for %q", requested)
 	}
+	canonicalUsername := requested
+	if strings.EqualFold(strings.TrimSpace(u.Username), requested) && validUsernamePath(u.Username) {
+		canonicalUsername = strings.TrimSpace(u.Username)
+	}
 	title := strings.TrimSpace(u.FirstName + " " + u.LastName)
 	if title == "" {
-		title = u.Username
+		title = canonicalUsername
 	}
 	if err := validatePublicPeerText(title, u.About); err != nil {
-		return publicPeer{}, false, fmt.Errorf("invalid public user %q: %w", u.Username, err)
+		return publicPeer{}, false, fmt.Errorf("invalid public user %q: %w", requested, err)
 	}
 	about := strings.TrimSpace(u.About)
 	photoKind := domain.ProfilePhotoKindProfile
@@ -733,7 +738,7 @@ func (h *handler) publicUserPeer(ctx context.Context, requested string, u domain
 	}
 	peer := publicPeer{
 		kind:     publicPeerUser,
-		username: u.Username,
+		username: canonicalUsername,
 		title:    title,
 		about:    about,
 		verified: u.Verified,
@@ -756,15 +761,20 @@ func (h *handler) publicUserPeer(ctx context.Context, requested string, u domain
 }
 
 func (h *handler) publicChannelPeer(ctx context.Context, requested string, ch domain.Channel) (publicPeer, bool, error) {
-	if ch.ID == 0 || ch.Deleted || ch.ParticipantsCount < 0 || (!ch.Broadcast && !ch.Megagroup) || !strings.EqualFold(strings.TrimSpace(ch.Username), requested) || !validUsernamePath(ch.Username) {
+	requested = domain.NormalizeUsername(requested)
+	if ch.ID == 0 || ch.Deleted || ch.ParticipantsCount < 0 || (!ch.Broadcast && !ch.Megagroup) || !validUsernamePath(requested) {
 		return publicPeer{}, false, fmt.Errorf("channel username lookup returned invalid owner for %q", requested)
 	}
+	canonicalUsername := requested
+	if strings.EqualFold(strings.TrimSpace(ch.Username), requested) && validUsernamePath(ch.Username) {
+		canonicalUsername = strings.TrimSpace(ch.Username)
+	}
 	if err := validatePublicPeerText(ch.Title, ch.About); err != nil {
-		return publicPeer{}, false, fmt.Errorf("invalid public channel %q: %w", ch.Username, err)
+		return publicPeer{}, false, fmt.Errorf("invalid public channel %q: %w", requested, err)
 	}
 	peer := publicPeer{
 		kind:        publicPeerChannel,
-		username:    ch.Username,
+		username:    canonicalUsername,
 		title:       strings.TrimSpace(ch.Title),
 		about:       strings.TrimSpace(ch.About),
 		verified:    ch.Verified,
@@ -1044,21 +1054,7 @@ func validStarGiftSlugPath(slug string) bool {
 }
 
 func validUsernamePath(username string) bool {
-	if username == "" || len(username) < 5 || len(username) > 32 {
-		return false
-	}
-	for i, r := range username {
-		switch {
-		case r >= 'a' && r <= 'z', r >= 'A' && r <= 'Z':
-		case r >= '0' && r <= '9', r == '_':
-			if i == 0 {
-				return false
-			}
-		default:
-			return false
-		}
-	}
-	return true
+	return domain.ValidCollectibleUsername(domain.NormalizeUsername(username))
 }
 
 func linkKind(set domain.StickerSet) string {