feat(view-windows): exposer list_open_view_windows pour l'état du menu

Ajoute la commande Tauri `list_open_view_windows` qui retourne un
`ViewWindowSnapshot` (panel, label, visible) par fenêtre de panneau
détachée, avec le parseur `view_panel_from_window_label` (labels stables
et legacy suffixés du project id). Enregistre la commande dans le
handler. Backend seul pour le ticket #50 ; pas encore de consommateur
frontend.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/app-tauri/src/commands.rs

@@ -2336,6 +2336,18 @@ pub struct CloseViewWindowResponseDto {
     pub closed: bool,
 }
 
+/// Snapshot returned by `list_open_view_windows`.
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ViewWindowSnapshot {
+    /// Panel id rendered by the detached window.
+    pub panel: String,
+    /// Stable Tauri window label.
+    pub label: String,
+    /// Whether Tauri currently reports the OS window as visible.
+    pub visible: bool,
+}
+
 /// Payload emitted on `view-window://lifecycle`.
 #[derive(Debug, Clone, Serialize)]
 #[serde(rename_all = "camelCase")]
@@ -2429,6 +2441,19 @@ pub(crate) fn view_window_url(panel: ViewPanel) -> String {
     format!("index.html?panel={}", panel.as_str())
 }
 
+fn view_panel_from_window_label(label: &str) -> Option<ViewPanel> {
+    let rest = label.strip_prefix("view-")?;
+    if let Ok(panel) = ViewPanel::parse(rest) {
+        return Some(panel);
+    }
+
+    let (panel, project_id) = rest.rsplit_once('-')?;
+    if project_id.len() != 32 || uuid::Uuid::parse_str(project_id).is_err() {
+        return None;
+    }
+    ViewPanel::parse(panel).ok()
+}
+
 pub(crate) fn emit_view_window_lifecycle(
     app: &AppHandle,
     kind: &'static str,
@@ -2468,6 +2493,30 @@ pub async fn get_focused_project(
     Ok(state.get_focused_project())
 }
 
+/// `list_open_view_windows` — return the detached panel windows currently
+/// registered by Tauri.
+#[tauri::command]
+pub fn list_open_view_windows(app: AppHandle) -> Vec<ViewWindowSnapshot> {
+    let mut windows = app
+        .webview_windows()
+        .into_iter()
+        .filter_map(|(label, window)| {
+            let panel = view_panel_from_window_label(&label)?;
+            Some(ViewWindowSnapshot {
+                panel: panel.as_str().to_owned(),
+                label,
+                visible: window.is_visible().unwrap_or(true),
+            })
+        })
+        .collect::<Vec<_>>();
+    windows.sort_by(|left, right| {
+        left.panel
+            .cmp(&right.panel)
+            .then(left.label.cmp(&right.label))
+    });
+    windows
+}
+
 /// `open_view_window` — open or focus a detached OS window for one panel.
 ///
 /// The window is a normal decorated, resizable system window. Its webview loads
@@ -2578,6 +2627,42 @@ mod view_window_tests {
         assert!(err.message.contains("invalid view panel: terminal"));
     }
 
+    #[test]
+    fn view_window_label_parser_accepts_stable_and_legacy_labels() {
+        assert_eq!(
+            view_panel_from_window_label("view-tickets")
+                .unwrap()
+                .as_str(),
+            "tickets"
+        );
+        assert_eq!(
+            view_panel_from_window_label("view-tickets-0000000000000000000000000000002a")
+                .unwrap()
+                .as_str(),
+            "tickets"
+        );
+        assert!(view_panel_from_window_label("main").is_none());
+        assert!(view_panel_from_window_label("view-unknown").is_none());
+        assert!(view_panel_from_window_label("view-tickets-not-a-project").is_none());
+    }
+
+    #[test]
+    fn view_window_snapshot_payload_is_camel_case() {
+        let payload = ViewWindowSnapshot {
+            panel: "tickets".to_owned(),
+            label: "view-tickets".to_owned(),
+            visible: true,
+        };
+
+        let json = serde_json::to_string(&payload).unwrap();
+        assert!(json.contains("\"panel\":\"tickets\""), "json was {json}");
+        assert!(
+            json.contains("\"label\":\"view-tickets\""),
+            "json was {json}"
+        );
+        assert!(json.contains("\"visible\":true"), "json was {json}");
+    }
+
     #[test]
     fn view_window_lifecycle_payload_is_camel_case() {
         let payload = ViewWindowLifecycleEventDto {

crates/app-tauri/src/lib.rs

@@ -264,6 +264,7 @@ pub fn run() {
             commands::resolve_memory_links,
             commands::set_focused_project,
             commands::get_focused_project,
+            commands::list_open_view_windows,
             commands::open_view_window,
             commands::close_view_window,
             commands::move_tab_to_new_window,