wayland: lang keys for the staged portal failures

Five keys, appended to `template.rs` and to every `src/lang/*.rs`. `it.rs` gets
empty values, as AGENTS.md requires -- it is maintained by hand by its
translator. No `en.rs` entries: each key is already its own English display
text, which is also what an older peer falls back to.

Two carry a `{}`: the portal's response code, and the name of the GStreamer
element that could not be created. `lang.rs`'s `extract_placeholder` resolves a
key by replacing the first `{...}` with `{}`, which is why the server sends the
value still inside the braces and why the scrap side strips braces out of any
detail before it gets there.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab

libs/scrap/src/wayland/pipewire.rs

@@ -516,14 +516,17 @@ fn stage_err(stage: &str, kind: &str, detail: &str) -> String {
     format!("wl-stage:{}:{}:{}", stage, kind, detail.trim())
 }
 
-fn dbus_detail(err: &dbus::Error) -> String {
-    match (err.name(), err.message()) {
+// The name alone is usually the generic `org.freedesktop.DBus.Error.Failed`; the message is
+// where a backend says what it objected to. This ends up in the log, so carry both.
+fn dbus_stage_err(stage: &str, err: &dbus::Error) -> String {
+    let detail = match (err.name(), err.message()) {
         (Some(name), Some(message)) if !name.is_empty() && !message.is_empty() => {
             format!("{}: {}", name, message)
         }
         (Some(name), _) if !name.is_empty() => name.to_owned(),
         (_, message) => message.unwrap_or_default().to_owned(),
-    }
+    };
+    stage_err(stage, "dbus", &detail)
 }
 
 #[derive(Clone)]
@@ -746,8 +749,8 @@ pub fn request_remote_desktop(
             INIT = true;
         }
     }
-    let conn = SyncConnection::new_session()
-        .map_err(|e| anyhow!(stage_err("session-bus", "dbus", &dbus_detail(&e))))?;
+    let conn =
+        SyncConnection::new_session().map_err(|e| anyhow!(dbus_stage_err("session-bus", &e)))?;
     let portal = get_portal(&conn);
     let mut args: PropMap = HashMap::new();
     let fd: Arc<Mutex<Option<OwnedFd>>> = Arc::new(Mutex::new(None));
@@ -783,7 +786,8 @@ pub fn request_remote_desktop(
     // the caller to subscribe to the signal before making the method call.
     handle_response(
         &conn,
-        get_request_path(&conn, create_session_handle_token)?,
+        get_request_path(&conn, create_session_handle_token)
+            .map_err(|e| anyhow!(dbus_stage_err("create-session", &e)))?,
         on_create_session_response(
             fd.clone(),
             streams.clone(),
@@ -794,18 +798,20 @@ pub fn request_remote_desktop(
         ),
         trace.clone(),
         PortalStage::CreateSession,
-    )?;
+    )
+    .map_err(|e| anyhow!(dbus_stage_err("create-session", &e)))?;
     if is_server_running() {
         let _ = screencast_portal::create_session(&portal, args)
-            .map_err(|e| anyhow!(stage_err("create-session", "dbus", &dbus_detail(&e))))?;
+            .map_err(|e| anyhow!(dbus_stage_err("create-session", &e)))?;
     } else {
         let _ = remote_desktop_portal::create_session(&portal, args)
-            .map_err(|e| anyhow!(stage_err("create-session", "dbus", &dbus_detail(&e))))?;
+            .map_err(|e| anyhow!(dbus_stage_err("create-session", &e)))?;
     }
 
     // wait 3 minutes for user interaction
     for _ in 0..1800 {
-        conn.process(Duration::from_millis(100))?;
+        conn.process(Duration::from_millis(100))
+            .map_err(|e| anyhow!(dbus_stage_err(trace_res.waiting_stage().as_str(), &e)))?;
         // Once we got a file descriptor we are done!
         if fd_res.lock().unwrap().is_some() {
             break;

src/lang/cn.rs

@@ -770,7 +770,7 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("port-forward-mux-tip", "同一条端口转发规则上的所有连接共用一条到对方的连接，而不是每条连接都重新连接并登录一次。"),
         ("Enable WebRTC P2P connection", "启用 WebRTC P2P 连接"),
         ("Enable TCP hole punching", "启用 TCP 打洞"),
-        ("The screen sharing request was declined on the remote device", "远程设备上拒绝了屏幕共享请求"),
+        ("The screen sharing request was declined on the remote device", "远程设备上的用户拒绝了屏幕共享请求"),
         ("No one responded to the screen sharing request on the remote device", "远程设备上无人响应屏幕共享请求"),
         ("The XDG Desktop Portal ended the screen sharing request ({})", "XDG Desktop Portal 结束了屏幕共享请求 ({})"),
         ("The XDG Desktop Portal returned no screen to capture, the PipeWire library may be too old", "XDG Desktop Portal 未返回可捕获的屏幕，PipeWire 库可能过旧"),

src/lang/tw.rs

@@ -770,7 +770,7 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("port-forward-mux-tip", "同一條連接埠轉送規則上的所有連線共用一條到對方的連線，而不是每條連線都重新連線並登入一次。"),
         ("Enable WebRTC P2P connection", "啟用 WebRTC P2P 連線"),
         ("Enable TCP hole punching", "啟用 TCP 打洞"),
-        ("The screen sharing request was declined on the remote device", "遠端裝置上拒絕了螢幕分享要求"),
+        ("The screen sharing request was declined on the remote device", "遠端裝置上的使用者拒絕了螢幕分享要求"),
         ("No one responded to the screen sharing request on the remote device", "遠端裝置上無人回應螢幕分享要求"),
         ("The XDG Desktop Portal ended the screen sharing request ({})", "XDG Desktop Portal 結束了螢幕分享要求 ({})"),
         ("The XDG Desktop Portal returned no screen to capture, the PipeWire library may be too old", "XDG Desktop Portal 未傳回可擷取的螢幕，PipeWire 函式庫可能過舊"),