feat: RDP dynamic resize on window resize (MobaXTerm-style)

When the Wraith window is resized, the RDP session now resizes to fill
the entire canvas area — matching MobaXTerm behavior.

Implementation:
- Enabled ironrdp displaycontrol feature for Display Control Virtual Channel
- Added Resize input event to RDP session thread
- ActiveStage::encode_resize() sends monitor layout PDU to server
- Server re-renders at new resolution and sends updated frames
- Frontend ResizeObserver on canvas wrapper, debounced 500ms
- Canvas CSS changed from max-width/max-height to width/height: 100%
- Mouse coordinate mapping uses canvas.width/height (actual resolution)
  instead of initial rdpWidth/rdpHeight
- Image and front buffer reallocated on resize to match new dimensions
- Width constrained to even numbers per RDP spec, min 200px

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -2991,6 +2991,7 @@ checksum = "47c225751e8fbfaaaac5572a80e25d0a0921e9cf408c55509526161b5609157c"
 dependencies = [
  "ironrdp-connector",
  "ironrdp-core",
+ "ironrdp-displaycontrol",
  "ironrdp-graphics",
  "ironrdp-input",
  "ironrdp-pdu",

src-tauri/Cargo.toml

@@ -65,7 +65,7 @@ ureq = "3"
 png = "0.17"
 
 # RDP (IronRDP)
-ironrdp = { version = "0.14", features = ["connector", "session", "graphics", "input"] }
+ironrdp = { version = "0.14", features = ["connector", "session", "graphics", "input", "displaycontrol"] }
 ironrdp-tokio = { version = "0.8", features = ["reqwest-rustls-ring"] }
 ironrdp-tls = { version = "0.2", features = ["rustls"] }
 tokio-rustls = "0.26"

src-tauri/src/commands/rdp_commands.rs

@@ -101,6 +101,19 @@ pub fn rdp_send_clipboard(
     state.rdp.send_clipboard(&session_id, &text)
 }
 
+/// Resize the RDP session's desktop resolution.
+/// Sends a Display Control Virtual Channel request to the server.
+/// The server will re-render at the new resolution and send updated frames.
+#[tauri::command]
+pub fn rdp_resize(
+    session_id: String,
+    width: u16,
+    height: u16,
+    state: State<'_, AppState>,
+) -> Result<(), String> {
+    state.rdp.resize(&session_id, width, height)
+}
+
 /// Disconnect an RDP session.
 ///
 /// Sends a graceful shutdown to the RDP server and removes the session.

src-tauri/src/lib.rs

@@ -224,7 +224,7 @@ pub fn run() {
             commands::credentials::list_credentials, commands::credentials::create_password, commands::credentials::create_ssh_key, commands::credentials::delete_credential, commands::credentials::decrypt_password, commands::credentials::decrypt_ssh_key,
             commands::ssh_commands::connect_ssh, commands::ssh_commands::connect_ssh_with_key, commands::ssh_commands::ssh_write, commands::ssh_commands::ssh_resize, commands::ssh_commands::disconnect_ssh, commands::ssh_commands::disconnect_session, commands::ssh_commands::list_ssh_sessions,
             commands::sftp_commands::sftp_list, commands::sftp_commands::sftp_read_file, commands::sftp_commands::sftp_write_file, commands::sftp_commands::sftp_mkdir, commands::sftp_commands::sftp_delete, commands::sftp_commands::sftp_rename,
-            commands::rdp_commands::connect_rdp, commands::rdp_commands::rdp_get_frame, commands::rdp_commands::rdp_send_mouse, commands::rdp_commands::rdp_send_key, commands::rdp_commands::rdp_send_clipboard, commands::rdp_commands::disconnect_rdp, commands::rdp_commands::list_rdp_sessions,
+            commands::rdp_commands::connect_rdp, commands::rdp_commands::rdp_get_frame, commands::rdp_commands::rdp_send_mouse, commands::rdp_commands::rdp_send_key, commands::rdp_commands::rdp_send_clipboard, commands::rdp_commands::rdp_resize, commands::rdp_commands::disconnect_rdp, commands::rdp_commands::list_rdp_sessions,
             commands::theme_commands::list_themes, commands::theme_commands::get_theme,
             commands::pty_commands::list_available_shells, commands::pty_commands::spawn_local_shell, commands::pty_commands::pty_write, commands::pty_commands::pty_resize, commands::pty_commands::disconnect_pty,
             commands::mcp_commands::mcp_list_sessions, commands::mcp_commands::mcp_terminal_read, commands::mcp_commands::mcp_terminal_execute, commands::mcp_commands::mcp_get_session_context, commands::mcp_commands::mcp_bridge_path,

src-tauri/src/rdp/mod.rs

@@ -63,6 +63,7 @@ enum InputEvent {
         pressed: bool,
     },
     Clipboard(String),
+    Resize { width: u16, height: u16 },
     Disconnect,
 }
 
@@ -299,6 +300,11 @@ impl RdpService {
         handle.input_tx.send(InputEvent::Key { scancode, pressed }).map_err(|_| format!("RDP session {} input channel closed", session_id))
     }
 
+    pub fn resize(&self, session_id: &str, width: u16, height: u16) -> Result<(), String> {
+        let handle = self.sessions.get(session_id).ok_or_else(|| format!("RDP session {} not found", session_id))?;
+        handle.input_tx.send(InputEvent::Resize { width, height }).map_err(|_| format!("RDP session {} input channel closed", session_id))
+    }
+
     pub fn disconnect(&self, session_id: &str) -> Result<(), String> {
         let handle = self.sessions.get(session_id).ok_or_else(|| format!("RDP session {} not found", session_id))?;
         let _ = handle.input_tx.send(InputEvent::Disconnect);
@@ -386,7 +392,7 @@ async fn establish_connection(config: connector::Config, hostname: &str, port: u
     Ok((connection_result, upgraded_framed))
 }
 
-async fn run_active_session(connection_result: ConnectionResult, framed: UpgradedFramed, front_buffer: Arc<std::sync::RwLock<Vec<u8>>>, dirty_region: Arc<std::sync::Mutex<Option<DirtyRect>>>, frame_dirty: Arc<AtomicBool>, mut input_rx: mpsc::UnboundedReceiver<InputEvent>, width: u16, height: u16, app_handle: tauri::AppHandle, session_id: String) -> Result<(), String> {
+async fn run_active_session(connection_result: ConnectionResult, framed: UpgradedFramed, front_buffer: Arc<std::sync::RwLock<Vec<u8>>>, dirty_region: Arc<std::sync::Mutex<Option<DirtyRect>>>, frame_dirty: Arc<AtomicBool>, mut input_rx: mpsc::UnboundedReceiver<InputEvent>, mut width: u16, mut height: u16, app_handle: tauri::AppHandle, session_id: String) -> Result<(), String> {
     let (mut reader, mut writer) = split_tokio_framed(framed);
     let mut image = DecodedImage::new(PixelFormat::RgbA32, width, height);
     let mut active_stage = ActiveStage::new(connection_result);
@@ -438,6 +444,24 @@ async fn run_active_session(connection_result: ConnectionResult, framed: Upgrade
                         }
                         all_outputs
                     }
+                    Some(InputEvent::Resize { width: new_w, height: new_h }) => {
+                        // Ensure dimensions are within RDP spec (200-8192, even width)
+                        let w = (new_w.max(200).min(8192) & !1) as u32;
+                        let h = new_h.max(200).min(8192) as u32;
+                        if let Some(Ok(resize_frame)) = active_stage.encode_resize(w, h, None, None) {
+                            writer.write_all(&resize_frame).await.map_err(|e| format!("Failed to send resize: {}", e))?;
+                            // Reallocate image and front buffer for new dimensions
+                            image = DecodedImage::new(PixelFormat::RgbA32, w as u16, h as u16);
+                            let buf_size = w as usize * h as usize * 4;
+                            let mut new_buf = vec![0u8; buf_size];
+                            for pixel in new_buf.chunks_exact_mut(4) { pixel[3] = 255; }
+                            *front_buffer.write().unwrap_or_else(|e| e.into_inner()) = new_buf;
+                            width = w as u16;
+                            height = h as u16;
+                            info!("RDP session {} resized to {}x{}", session_id, width, height);
+                        }
+                        Vec::new()
+                    }
                 }
             }
         };

src/components/rdp/RdpView.vue

@@ -29,6 +29,7 @@
 
 <script setup lang="ts">
 import { ref, computed, onMounted, onBeforeUnmount, watch } from "vue";
+import { invoke } from "@tauri-apps/api/core";
 import { useRdp, MouseFlag } from "@/composables/useRdp";
 
 const props = defineProps<{
@@ -76,8 +77,8 @@ function toRdpCoords(e: MouseEvent): { x: number; y: number } | null {
   if (!canvas) return null;
 
   const rect = canvas.getBoundingClientRect();
-  const scaleX = rdpWidth.value / rect.width;
-  const scaleY = rdpHeight.value / rect.height;
+  const scaleX = canvas.width / rect.width;
+  const scaleY = canvas.height / rect.height;
 
   return {
     x: Math.floor((e.clientX - rect.left) * scaleX),
@@ -153,14 +154,51 @@ function handleKeyUp(e: KeyboardEvent): void {
   sendKey(props.sessionId, e.code, false);
 }
 
+let resizeObserver: ResizeObserver | null = null;
+let resizeTimeout: ReturnType<typeof setTimeout> | null = null;
+
 onMounted(() => {
   if (canvasRef.value) {
     startFrameLoop(props.sessionId, canvasRef.value, rdpWidth.value, rdpHeight.value);
   }
+
+  // Watch container size and request server-side RDP resize (debounced 500ms)
+  if (canvasWrapper.value) {
+    resizeObserver = new ResizeObserver((entries) => {
+      const entry = entries[0];
+      if (!entry || !connected.value) return;
+      const { width: cw, height: ch } = entry.contentRect;
+      if (cw < 200 || ch < 200) return;
+
+      // Round to even width (RDP spec requirement)
+      const newW = Math.round(cw) & ~1;
+      const newH = Math.round(ch);
+
+      if (resizeTimeout) clearTimeout(resizeTimeout);
+      resizeTimeout = setTimeout(() => {
+        invoke("rdp_resize", {
+          sessionId: props.sessionId,
+          width: newW,
+          height: newH,
+        }).then(() => {
+          // Update canvas dimensions to match new RDP resolution
+          if (canvasRef.value) {
+            canvasRef.value.width = newW;
+            canvasRef.value.height = newH;
+          }
+        }).catch((err: unknown) => {
+          console.warn("[RdpView] resize failed:", err);
+        });
+      }, 500);
+    });
+    resizeObserver.observe(canvasWrapper.value);
+  }
 });
 
 onBeforeUnmount(() => {
   stopFrameLoop();
+  if (resizeObserver) { resizeObserver.disconnect(); resizeObserver = null; }
+  if (resizeTimeout) { clearTimeout(resizeTimeout); resizeTimeout = null; }
 });
 
 // Focus canvas when this tab becomes active and keyboard is grabbed
@@ -196,9 +234,8 @@ watch(
 }
 
 .rdp-canvas {
-  max-width: 100%;
-  max-height: 100%;
-  object-fit: contain;
+  width: 100%;
+  height: 100%;
   cursor: default;
   outline: none;
   image-rendering: auto;