feat(slint): hover tooltip on collapsed-sidebar folder/playlist rows

In the mini (icon-only) sidebar the rows show no name. Add a hover bubble
to the right of each folder/top-level-playlist row surfacing the name
(folders also append their playlist count), mirroring the native title
Tauri puts on its collapsed buttons. Rendered at the AppShell level
(SidebarTooltip + SidebarTooltipState) because the sidebar clips its
overflow; anchored with the same Flickable absolute-position correction as
the folder flyout. Closes on click so it does not linger behind the flyout.

cc

crates/qbz-slint/ui/shell/AppShell.slint

@@ -12,6 +12,7 @@ import { Sidebar } from "Sidebar.slint";
 import { HeaderBar } from "HeaderBar.slint";
 import { HeaderMenuOverlay } from "HeaderMenuOverlay.slint";
 import { SidebarFolderPopup } from "SidebarFolderPopup.slint";
+import { SidebarTooltip } from "SidebarTooltip.slint";
 import { PlaylistPickerModal } from "../primitives/PlaylistPickerModal.slint";
 import { CreatePlaylistModal } from "../primitives/CreatePlaylistModal.slint";
 import { EditPlaylistModal } from "../primitives/EditPlaylistModal.slint";
@@ -299,6 +300,9 @@ export component AppShell inherits Rectangle {
     // Collapsed-sidebar folder flyout (mini state). Drawn above the content.
     SidebarFolderPopup { }
 
+    // Collapsed-sidebar hover tooltip (mini state) — name + folder count.
+    SidebarTooltip { }
+
     // Global "Add to playlist" picker overlay, opened from any track
     // context menu.
     PlaylistPickerModal { }

crates/qbz-slint/ui/shell/Sidebar.slint

@@ -15,7 +15,7 @@ import { QbzIcon } from "../primitives/QbzIcon.slint";
 import { SidebarPlaylistCollage } from "../primitives/SidebarPlaylistCollage.slint";
 import { ContextMenu } from "../primitives/ContextMenu.slint";
 import { ContextMenuItem } from "../primitives/ContextMenuItem.slint";
-import { ShellState, SidebarState, SidebarActions, SidebarEntry, DragState, HeaderMenuState, NavMenuEntry, SidebarFolderPopupState } from "../state.slint";
+import { ShellState, SidebarState, SidebarActions, SidebarEntry, DragState, HeaderMenuState, NavMenuEntry, SidebarFolderPopupState, SidebarTooltipState } from "../state.slint";
 import { ScrollView, LineEdit } from "std-widgets.slint";
 
 // A single context-menu item row.
@@ -163,6 +163,29 @@ component SidebarRow inherits Rectangle {
     changed drag-py => { root.recompute-drop(); }
     changed drag-on => { root.recompute-drop(); }
 
+    // Collapsed (mini) hover tooltip: the row shows only an icon, so reveal the
+    // name (folders also show their playlist count) in a bubble to the right.
+    // Same Flickable absolute-position correction as the folder flyout anchor.
+    function show-tooltip() {
+        if (!ShellState.sidebar-mini) {
+            return;
+        }
+        SidebarTooltipState.id = root.entry.id;
+        SidebarTooltipState.text = root.is-folder
+            ? root.entry.name + " (" + root.entry.count + ")"
+            : root.entry.name;
+        SidebarTooltipState.anchor-x = root.absolute-position.x - root.x + root.width + 6px;
+        SidebarTooltipState.anchor-y = root.absolute-position.y - root.y;
+        SidebarTooltipState.open = true;
+    }
+    // Close only if this row still owns the tooltip (race-safe when the pointer
+    // slides directly from one row to the next).
+    function hide-tooltip() {
+        if (SidebarTooltipState.id == root.entry.id) {
+            SidebarTooltipState.open = false;
+        }
+    }
+
     // True when this playlist row should show its micro-collage instead
     // of the generic glyph (opt-out + at least one cover available).
     property <bool> use-collage: !root.is-folder
@@ -276,8 +299,16 @@ component SidebarRow inherits Rectangle {
         mouse-cursor: pointer;
         changed has-hover => {
             root.hover-changed(self.has-hover);
+            if (self.has-hover) {
+                root.show-tooltip();
+            } else {
+                root.hide-tooltip();
+            }
         }
         clicked => {
+            // The flyout / navigation takes over from here — drop the tooltip
+            // so it doesn't linger behind the opening flyout.
+            SidebarTooltipState.open = false;
             if (root.is-folder) {
                 // Collapsed (mini) sidebar: a folder opens a flyout to the
                 // right instead of expanding downward (Tauri parity).

crates/qbz-slint/ui/shell/SidebarTooltip.slint

@@ -0,0 +1,44 @@
+// Collapsed-sidebar hover tooltip. When the sidebar is in the mini (icon-only)
+// state, hovering a folder or top-level playlist row surfaces its name in a
+// small bubble to the right (folders append their playlist count). Mirrors the
+// native `title` Tauri puts on the collapsed buttons. Rendered at the AppShell
+// level because the sidebar clips its own overflow. Visual only (no TouchArea),
+// so it never blocks the pointer.
+
+import { Theme } from "../foundation/semantic-colors.slint";
+import { Radius } from "../foundation/radius.slint";
+import { SidebarTooltipState, ShellState } from "../state.slint";
+
+export component SidebarTooltip inherits Rectangle {
+    // Auto-hides if the sidebar leaves the mini state while a tooltip lingers.
+    visible: SidebarTooltipState.open && ShellState.sidebar-mini;
+
+    if SidebarTooltipState.open && ShellState.sidebar-mini: bubble := Rectangle {
+        x: SidebarTooltipState.anchor-x;
+        // Center the bubble against the 32px row.
+        y: SidebarTooltipState.anchor-y + (32px - self.height) / 2;
+        width: row.preferred-width;
+        height: row.preferred-height;
+        background: Theme.surface-elevated;
+        border-radius: Radius.sm;
+        border-width: 1px;
+        border-color: Theme.border-muted;
+        drop-shadow-blur: 16px;
+        drop-shadow-color: Theme.card-shadow;
+        drop-shadow-offset-y: 4px;
+
+        row := HorizontalLayout {
+            padding-left: 10px;
+            padding-right: 10px;
+            padding-top: 5px;
+            padding-bottom: 5px;
+            Text {
+                text: SidebarTooltipState.text;
+                color: Theme.text-primary;
+                font-size: 12px;
+                font-weight: 500;
+                vertical-alignment: center;
+            }
+        }
+    }
+}

crates/qbz-slint/ui/state.slint

@@ -818,6 +818,20 @@ export global SidebarFolderPopupState {
     in property <[SidebarEntry]> playlists: [];
 }
 
+// Collapsed (mini) sidebar hover tooltip — the row shows only an icon, so a
+// hover bubble surfaces the name (folders also show their playlist count).
+// Mirrors Tauri's native `title` on the collapsed folder/playlist buttons.
+// Rendered at the AppShell level because the sidebar clips its overflow; the
+// anchor is the row's true window position (the collapsed rows live inside a
+// Flickable, so SidebarRow corrects the absolute-position double-count).
+export global SidebarTooltipState {
+    in-out property <bool> open: false;
+    in-out property <string> id;        // owning row id (race-safe leave)
+    in-out property <string> text;      // "Folder (N)" or "Playlist name"
+    in-out property <length> anchor-x;  // window x (sidebar right edge)
+    in-out property <length> anchor-y;  // window y (row top)
+}
+
 // The sidebar's playlists + folders. Populated by crate::sidebar on
 // shell entry and after create/delete/move.
 export global SidebarState {