fix(agents): attach pasted clipboard images on Linux (#2336)

WebKitGTK hands the composer an empty clipboardData when the clipboard
holds only an image, as after a GNOME screenshot, and refuses
navigator.clipboard.read(). Ctrl+V then attached nothing. A paste that
carries no data now reads the image through the GTK clipboard with the
new clipboard_image command.

Co-authored-by: NealimeKenna <[email protected]>

src-tauri/src/commands/clipboard.rs

@@ -31,6 +31,39 @@ pub async fn clipboard_set_file_list(app: AppHandle, paths: Vec<PathBuf>) -> Ide
     with_clipboard(app, move || Ok(ide_clipboard::set_files(&paths))).await
 }
 
+/// The clipboard's image as a PNG data URL, for a paste whose event carried no
+/// files: WebKitGTK leaves `clipboardData` empty for a raw image (a screenshot).
+/// None when the clipboard holds no image, and always on other platforms.
+#[tauri::command]
+#[specta::specta]
+pub async fn clipboard_image(app: AppHandle) -> IdeResult<Option<String>> {
+    #[cfg(target_os = "linux")]
+    {
+        use base64::Engine;
+        let (tx, rx) = tokio::sync::oneshot::channel();
+        app.run_on_main_thread(move || {
+            let sender = std::cell::Cell::new(Some(tx));
+            gtk::Clipboard::get(&gtk::gdk::SELECTION_CLIPBOARD).request_image(move |_, pixbuf| {
+                let png = pixbuf.and_then(|image| image.save_to_bufferv("png", &[]).ok());
+                if let Some(sender) = sender.take() {
+                    let _ = sender.send(png);
+                }
+            });
+        })
+        .map_err(|error| {
+            ide_core::IdeError::internal(format!("Cannot dispatch clipboard access to the main thread: {error}"))
+        })?;
+        let png = rx.await.ok().flatten();
+        Ok(png
+            .map(|bytes| format!("data:image/png;base64,{}", base64::engine::general_purpose::STANDARD.encode(bytes))))
+    }
+    #[cfg(not(target_os = "linux"))]
+    {
+        let _ = app;
+        Ok(None)
+    }
+}
+
 /// AppKit and WebKit share the general pasteboard, so a worker-side mutex cannot
 /// protect its type cache. Await the main thread without blocking a command thread.
 async fn with_clipboard<T: Send + 'static>(

src-tauri/src/commands/mod.rs

@@ -166,6 +166,7 @@ pub fn builder() -> tauri_specta::Builder<tauri::Wry> {
         fs::fs_read_text,
         clipboard::clipboard_file_list,
         clipboard::clipboard_has_files,
+        clipboard::clipboard_image,
         clipboard::clipboard_set_file_list,
         fonts::system_font_families,
         doc::doc_open,