Make multi-window rock steady

Found some critical race conditions that might've led to app crashes in the past.

Author: vdavid

apps/desktop/src-tauri/src/lib.rs

@@ -323,7 +323,8 @@ pub fn run() {
                     serde_json::json!({ "action": "sortOrder", "value": order }),
                 );
             } else if id == VIEWER_WORD_WRAP_ID {
-                // Find the focused viewer window and emit toggle event to it
+                // Toggle word wrap on the focused viewer window (if any).
+                // Safe: unwrap_or(false) handles destroyed windows, `let _ =` ignores emit errors.
                 for (label, window) in app.webview_windows() {
                     if label.starts_with("viewer-") && window.is_focused().unwrap_or(false) {
                         let _ = app.emit_to(&label, "viewer-word-wrap-toggled", ());
@@ -598,8 +599,10 @@ pub fn run() {
                 network::mdns_discovery::stop_discovery();
                 window.app_handle().exit(0);
             }
-            // Also handle window destruction for cleanup
-            if let tauri::WindowEvent::Destroyed = event {
+            // Clean up app-wide resources only when the main window is destroyed
+            if let tauri::WindowEvent::Destroyed = event
+                && window.label() == "main"
+            {
                 ai::manager::shutdown();
                 #[cfg(target_os = "macos")]
                 network::mdns_discovery::stop_discovery();

apps/desktop/src-tauri/src/mcp/executor.rs

@@ -543,7 +543,9 @@ fn execute_dialog_close<R: Runtime>(app: &AppHandle<R>, dialog_type: &str, path:
 
     match dialog_type {
         "settings" => {
-            app.emit_to("settings", "mcp-settings-close", ())?;
+            if app.webview_windows().contains_key("settings") {
+                app.emit_to("settings", "mcp-settings-close", ())?;
+            }
             Ok(json!("OK: Closed settings"))
         }
         "file-viewer" => {

apps/desktop/src/routes/(main)/+page.svelte

@@ -197,14 +197,24 @@
             await emitToFileViewers('mcp-viewer-close', { path })
         } else {
             // Close the most recent viewer directly
-            await viewers[0].close()
+            try {
+                await viewers[0].close()
+            } catch {
+                // Window may already be closed
+            }
         }
     }
 
-    /** Close all file viewer windows */
+    /** Close all file viewer windows sequentially to avoid concurrent destruction races */
     async function closeAllFileViewers() {
         const viewers = await getFileViewerWindows()
-        await Promise.all(viewers.map((v) => v.close()))
+        for (const viewer of viewers) {
+            try {
+                await viewer.close()
+            } catch {
+                // Window may already be closed
+            }
+        }
     }
 
     /** Focus a file viewer window. If path is provided, focuses the viewer with that path. Otherwise focuses the most recent. */
@@ -216,8 +226,11 @@
             // Emit event with path - the viewer with that path will focus itself
             await emitToFileViewers('mcp-viewer-focus', { path })
         } else {
-            // Focus the most recent viewer directly
-            await viewers[0].setFocus()
+            try {
+                await viewers[0].setFocus()
+            } catch {
+                // Window may already be closed
+            }
         }
     }
 

apps/desktop/src/routes/viewer/+page.svelte

@@ -96,6 +96,7 @@
     // Window lifecycle state: prevents closing before WebKit is fully initialized
     let windowReady = $state(false)
     let closeRequested = $state(false)
+    let closing = false
 
     // Event listener cleanup functions
     let unlistenMcpClose: UnlistenFn | undefined
@@ -437,12 +438,14 @@
     })
 
     function closeWindow() {
+        if (closing) return
         // If window isn't ready yet, queue the close for when it is
         if (!windowReady) {
             feLog('[viewer] closeWindow: window not ready, queueing close')
             closeRequested = true
             return
         }
+        closing = true
 
         const start = performance.now()
         feLog('[viewer] closeWindow: starting')