diff --git a/crates/chattyness-db/src/models.rs b/crates/chattyness-db/src/models.rs
index 9c4ac98..5d40fea 100644
--- a/crates/chattyness-db/src/models.rs
+++ b/crates/chattyness-db/src/models.rs
@@ -1829,6 +1829,9 @@ pub struct ChannelMemberInfo {
     /// Current emotion slot (0-9)
     pub current_emotion: i16,
     pub joined_at: DateTime<Utc>,
+    /// Whether this user is a guest (has the 'guest' tag)
+    #[serde(default)]
+    pub is_guest: bool,
 }
 
 /// Request to update position in a channel.
diff --git a/crates/chattyness-db/src/queries/channel_members.rs b/crates/chattyness-db/src/queries/channel_members.rs
index 74252d6..230a81e 100644
--- a/crates/chattyness-db/src/queries/channel_members.rs
+++ b/crates/chattyness-db/src/queries/channel_members.rs
@@ -176,7 +176,8 @@ pub async fn get_channel_members<'e>(
             cm.is_moving,
             cm.is_afk,
             COALESCE(aa.current_emotion, 0::smallint) as current_emotion,
-            cm.joined_at
+            cm.joined_at,
+            COALESCE('guest' = ANY(u.tags), false) as is_guest
         FROM scene.instance_members cm
         LEFT JOIN auth.users u ON cm.user_id = u.id
         LEFT JOIN auth.guest_sessions gs ON cm.guest_session_id = gs.id
@@ -214,7 +215,8 @@ pub async fn get_channel_member<'e>(
             cm.is_moving,
             cm.is_afk,
             COALESCE(aa.current_emotion, 0::smallint) as current_emotion,
-            cm.joined_at
+            cm.joined_at,
+            COALESCE('guest' = ANY(u.tags), false) as is_guest
         FROM scene.instance_members cm
         LEFT JOIN auth.users u ON cm.user_id = u.id
         LEFT JOIN auth.active_avatars aa ON cm.user_id = aa.user_id AND aa.realm_id = $3
diff --git a/crates/chattyness-user-ui/src/components/avatar_editor.rs b/crates/chattyness-user-ui/src/components/avatar_editor.rs
index b4bb3b6..b1d7a00 100644
--- a/crates/chattyness-user-ui/src/components/avatar_editor.rs
+++ b/crates/chattyness-user-ui/src/components/avatar_editor.rs
@@ -12,6 +12,7 @@ use chattyness_db::models::{AvatarWithPaths, InventoryItem};
 #[cfg(feature = "hydrate")]
 use chattyness_db::ws_messages::ClientMessage;
 
+use super::modals::GuestLockedOverlay;
 use super::ws_client::WsSenderStorage;
 #[cfg(feature = "hydrate")]
 use crate::utils::normalize_asset_path;
@@ -216,6 +217,7 @@ fn RenderedPreview(#[prop(into)] avatar: Signal<Option<AvatarWithPaths>>) -> imp
 /// - `realm_slug`: Current realm slug for API calls
 /// - `on_avatar_update`: Callback when avatar is updated
 /// - `ws_sender`: WebSocket sender for broadcasting avatar changes
+/// - `is_guest`: Whether the current user is a guest (shows locked overlay)
 #[component]
 pub fn AvatarEditorPopup(
     #[prop(into)] open: Signal<bool>,
@@ -224,7 +226,11 @@ pub fn AvatarEditorPopup(
     #[prop(into)] realm_slug: Signal<String>,
     on_avatar_update: Callback<AvatarWithPaths>,
     ws_sender: WsSenderStorage,
+    /// Whether the current user is a guest. Guests see a locked overlay.
+    #[prop(optional, into)]
+    is_guest: Option<Signal<bool>>,
 ) -> impl IntoView {
+    let is_guest = is_guest.unwrap_or_else(|| Signal::derive(|| false));
     // Tab state
     let (active_tab, set_active_tab) = signal(EditorTab::BaseLayers);
 
@@ -798,6 +804,11 @@ pub fn AvatarEditorPopup(
                             </div>
                         </div>
                     </div>
+
+                    // Guest locked overlay
+                    <Show when=move || is_guest.get()>
+                        <GuestLockedOverlay />
+                    </Show>
                 </div>
 
                 // Context menu
diff --git a/crates/chattyness-user-ui/src/components/inventory.rs b/crates/chattyness-user-ui/src/components/inventory.rs
index c9eaf67..add9e96 100644
--- a/crates/chattyness-user-ui/src/components/inventory.rs
+++ b/crates/chattyness-user-ui/src/components/inventory.rs
@@ -8,7 +8,7 @@ use chattyness_db::models::{InventoryItem, PublicProp};
 #[cfg(feature = "hydrate")]
 use chattyness_db::ws_messages::ClientMessage;
 
-use super::modals::Modal;
+use super::modals::{GuestLockedOverlay, Modal};
 use super::tabs::{Tab, TabBar};
 use super::ws_client::WsSender;
 
@@ -24,13 +24,18 @@ use super::ws_client::WsSender;
 /// - `on_close`: Callback when popup should close
 /// - `ws_sender`: WebSocket sender for dropping props
 /// - `realm_slug`: Current realm slug for fetching realm props
+/// - `is_guest`: Whether the current user is a guest (shows locked overlay)
 #[component]
 pub fn InventoryPopup(
     #[prop(into)] open: Signal<bool>,
     on_close: Callback<()>,
     ws_sender: StoredValue<Option<WsSender>, LocalStorage>,
     #[prop(into)] realm_slug: Signal<String>,
+    /// Whether the current user is a guest. Guests see a locked overlay.
+    #[prop(optional, into)]
+    is_guest: Option<Signal<bool>>,
 ) -> impl IntoView {
+    let is_guest = is_guest.unwrap_or_else(|| Signal::derive(|| false));
     // Tab state
     let (active_tab, set_active_tab) = signal("my_inventory");
 
@@ -238,52 +243,59 @@ pub fn InventoryPopup(
             max_width="max-w-2xl"
             class="max-h-[80vh] flex flex-col"
         >
-            // Tab bar
-            <TabBar
-                tabs=vec![
-                    Tab::new("my_inventory", "My Inventory"),
-                    Tab::new("server", "Server"),
-                    Tab::new("realm", "Realm"),
-                ]
-                active=Signal::derive(move || active_tab.get())
-                on_select=Callback::new(move |id| set_active_tab.set(id))
-            />
+            <div class="relative flex-1 flex flex-col">
+                // Tab bar
+                <TabBar
+                    tabs=vec![
+                        Tab::new("my_inventory", "My Inventory"),
+                        Tab::new("server", "Server"),
+                        Tab::new("realm", "Realm"),
+                    ]
+                    active=Signal::derive(move || active_tab.get())
+                    on_select=Callback::new(move |id| set_active_tab.set(id))
+                />
 
-            // Tab content
-            <div class="flex-1 overflow-y-auto min-h-[300px]">
-                // My Inventory tab
-                <Show when=move || active_tab.get() == "my_inventory">
-                    <MyInventoryTab
-                        items=items
-                        loading=loading
-                        error=error
-                        selected_item=selected_item
-                        set_selected_item=set_selected_item
-                        dropping=dropping
-                        on_drop=Callback::new(handle_drop)
-                    />
-                </Show>
+                // Tab content
+                <div class="flex-1 overflow-y-auto min-h-[300px]">
+                    // My Inventory tab
+                    <Show when=move || active_tab.get() == "my_inventory">
+                        <MyInventoryTab
+                            items=items
+                            loading=loading
+                            error=error
+                            selected_item=selected_item
+                            set_selected_item=set_selected_item
+                            dropping=dropping
+                            on_drop=Callback::new(handle_drop)
+                        />
+                    </Show>
 
-                // Server tab
-                <Show when=move || active_tab.get() == "server">
-                    <PublicPropsTab
-                        props=server_props
-                        loading=server_loading
-                        error=server_error
-                        tab_name="Server"
-                        empty_message="No public server props available"
-                    />
-                </Show>
+                    // Server tab
+                    <Show when=move || active_tab.get() == "server">
+                        <PublicPropsTab
+                            props=server_props
+                            loading=server_loading
+                            error=server_error
+                            tab_name="Server"
+                            empty_message="No public server props available"
+                        />
+                    </Show>
 
-                // Realm tab
-                <Show when=move || active_tab.get() == "realm">
-                    <PublicPropsTab
-                        props=realm_props
-                        loading=realm_loading
-                        error=realm_error
-                        tab_name="Realm"
-                        empty_message="No public realm props available"
-                    />
+                    // Realm tab
+                    <Show when=move || active_tab.get() == "realm">
+                        <PublicPropsTab
+                            props=realm_props
+                            loading=realm_loading
+                            error=realm_error
+                            tab_name="Realm"
+                            empty_message="No public realm props available"
+                        />
+                    </Show>
+                </div>
+
+                // Guest locked overlay
+                <Show when=move || is_guest.get()>
+                    <GuestLockedOverlay />
                 </Show>
             </div>
         </Modal>
diff --git a/crates/chattyness-user-ui/src/components/modals.rs b/crates/chattyness-user-ui/src/components/modals.rs
index 5baa588..3bcde67 100644
--- a/crates/chattyness-user-ui/src/components/modals.rs
+++ b/crates/chattyness-user-ui/src/components/modals.rs
@@ -314,3 +314,45 @@ pub fn ConfirmModal(
         </Show>
     }
 }
+
+// ============================================================================
+// Guest Locked Overlay
+// ============================================================================
+
+/// Overlay displayed when a feature is restricted to registered users.
+///
+/// Shows a semi-transparent backdrop with a padlock icon and diagonal
+/// "Registered Users" text. Designed to be placed inside a modal container
+/// with `position: relative`.
+///
+/// # Example
+///
+/// ```ignore
+/// <div class="relative">
+///     // Modal content here
+///     <GuestLockedOverlay />
+/// </div>
+/// ```
+#[component]
+pub fn GuestLockedOverlay() -> impl IntoView {
+    view! {
+        <div
+            class="absolute inset-0 z-50 flex items-center justify-center bg-gray-900/80 backdrop-blur-sm rounded-lg"
+            role="alert"
+            aria-label="This feature is restricted to registered users"
+        >
+            <div class="flex flex-col items-center gap-4 transform -rotate-12">
+                <img
+                    src="/icons/padlock.svg"
+                    alt=""
+                    class="w-16 h-16 text-gray-400"
+                    style="filter: invert(60%) sepia(0%) saturate(0%) hue-rotate(0deg) brightness(90%) contrast(90%);"
+                    aria-hidden="true"
+                />
+                <span class="text-2xl font-bold text-gray-400 tracking-wider uppercase whitespace-nowrap">
+                    "Registered Users"
+                </span>
+            </div>
+        </div>
+    }
+}
diff --git a/crates/chattyness-user-ui/src/components/scene_viewer.rs b/crates/chattyness-user-ui/src/components/scene_viewer.rs
index 664cac7..23dff40 100644
--- a/crates/chattyness-user-ui/src/components/scene_viewer.rs
+++ b/crates/chattyness-user-ui/src/components/scene_viewer.rs
@@ -56,10 +56,14 @@ pub fn RealmSceneViewer(
     /// Current user's guest_session_id (for context menu filtering).
     #[prop(optional, into)]
     current_guest_session_id: Option<Signal<Option<Uuid>>>,
+    /// Whether the current user is a guest (guests cannot use context menu).
+    #[prop(optional, into)]
+    is_guest: Option<Signal<bool>>,
     /// Callback when whisper is requested on a member.
     #[prop(optional, into)]
     on_whisper_request: Option<Callback<String>>,
 ) -> impl IntoView {
+    let is_guest = is_guest.unwrap_or_else(|| Signal::derive(|| false));
     // Use default settings if none provided
     let settings = settings.unwrap_or_else(|| Signal::derive(ViewerSettings::default));
     let dimensions = parse_bounds_dimensions(&scene.bounds_wkt);
@@ -183,14 +187,19 @@ pub fn RealmSceneViewer(
         move |ev: web_sys::MouseEvent| {
             use wasm_bindgen::JsCast;
 
-            // Get click position
-            let client_x = ev.client_x() as f64;
-            let client_y = ev.client_y() as f64;
+            // Guests cannot message other users - don't show context menu
+            if is_guest.get() {
+                return;
+            }
 
             // Get current user identity for filtering
             let my_user_id = current_user_id.map(|s| s.get()).flatten();
             let my_guest_session_id = current_guest_session_id.map(|s| s.get()).flatten();
 
+            // Get click position
+            let client_x = ev.client_x() as f64;
+            let client_y = ev.client_y() as f64;
+
             // Query all avatar canvases and check for hit
             let document = web_sys::window().unwrap().document().unwrap();
 
diff --git a/crates/chattyness-user-ui/src/components/ws_client.rs b/crates/chattyness-user-ui/src/components/ws_client.rs
index a4e6952..ef026fa 100644
--- a/crates/chattyness-user-ui/src/components/ws_client.rs
+++ b/crates/chattyness-user-ui/src/components/ws_client.rs
@@ -60,6 +60,8 @@ pub struct ChannelMemberInfo {
     pub guest_session_id: Option<uuid::Uuid>,
     /// The user's display name.
     pub display_name: String,
+    /// Whether this user is a guest (has the 'guest' tag).
+    pub is_guest: bool,
 }
 
 /// WebSocket error info for UI display.
@@ -240,6 +242,7 @@ pub fn use_channel_websocket(
                                 user_id: member.user_id,
                                 guest_session_id: member.guest_session_id,
                                 display_name: member.display_name.clone(),
+                                is_guest: member.is_guest,
                             };
                             callback.run(info);
                         }
diff --git a/crates/chattyness-user-ui/src/pages/realm.rs b/crates/chattyness-user-ui/src/pages/realm.rs
index 9a28abe..882847f 100644
--- a/crates/chattyness-user-ui/src/pages/realm.rs
+++ b/crates/chattyness-user-ui/src/pages/realm.rs
@@ -98,6 +98,8 @@ pub fn RealmPage() -> impl IntoView {
     // Current user identity (received from WebSocket Welcome message)
     let (current_user_id, set_current_user_id) = signal(Option::<Uuid>::None);
     let (current_guest_session_id, set_current_guest_session_id) = signal(Option::<Uuid>::None);
+    // Whether the current user is a guest (has the 'guest' tag)
+    let (is_guest, set_is_guest) = signal(false);
 
     // Whisper target - when set, triggers pre-fill in ChatInput
     let (whisper_target, set_whisper_target) = signal(Option::<String>::None);
@@ -313,6 +315,7 @@ pub fn RealmPage() -> impl IntoView {
         set_current_user_id.set(info.user_id);
         set_current_guest_session_id.set(info.guest_session_id);
         set_current_display_name.set(info.display_name.clone());
+        set_is_guest.set(info.is_guest);
     });
 
     // Callback for WebSocket errors (whisper failures, etc.)
@@ -772,6 +775,7 @@ pub fn RealmPage() -> impl IntoView {
                                                                                 fading_members=Signal::derive(move || fading_members.get())
                                                                                 current_user_id=Signal::derive(move || current_user_id.get())
                                                                                 current_guest_session_id=Signal::derive(move || current_guest_session_id.get())
+                                                                                is_guest=Signal::derive(move || is_guest.get())
                                                                                 on_whisper_request=on_whisper_request_cb
                                                                             />
                                                                             <div class="absolute bottom-0 left-0 right-0 z-10 pb-4 px-4 pointer-events-none">
@@ -823,6 +827,7 @@ pub fn RealmPage() -> impl IntoView {
                                                     })
                                                     ws_sender=ws_sender_for_inv
                                                     realm_slug=Signal::derive(move || slug.get())
+                                                    is_guest=Signal::derive(move || is_guest.get())
                                                 />
                                             }
                                         }
@@ -867,6 +872,7 @@ pub fn RealmPage() -> impl IntoView {
                                                         set_skin_preview_path.set(updated.skin_layer[4].clone());
                                                     })
                                                     ws_sender=ws_sender_for_avatar
+                                                    is_guest=Signal::derive(move || is_guest.get())
                                                 />
                                             }
                                         }