feat(cliprdr): add CliprdrBackend::on_format_list_response(ok) hook

crates/ironrdp-cliprdr/src/backend.rs

@@ -83,6 +83,23 @@ pub trait CliprdrBackend: AsAny + core::fmt::Debug + Send {
     /// client's clipboard prior to `CLIPRDR` SVC initialization.
     fn on_request_format_list(&mut self);
 
+    /// Called by [`crate::Cliprdr`] when the remote responds to a `FormatList` we
+    /// sent (i.e. an outbound advertise of our own clipboard contents).
+    ///
+    /// `ok = true` means the remote accepted the list (`CB_RESPONSE_OK`);
+    /// `ok = false` means it rejected it (`CB_RESPONSE_FAIL`), and
+    /// [`crate::Cliprdr`] has already cleared
+    /// `local_file_list` / `local_file_list_format_id` per MS-RDPECLIP 3.1.5.2.4.
+    ///
+    /// Backends can use this to retry on `Fail` (e.g. ride out a transient
+    /// rejection caused by the remote window being inactive at the instant we
+    /// advertised) and, equally important, to **stop** re-advertising once an
+    /// `Ok` is seen — a later blind re-advertise that gets rejected would wipe
+    /// already-accepted state and silently break a paste that was about to work.
+    ///
+    /// Default impl is a no-op, so this is non-breaking for existing backends.
+    fn on_format_list_response(&mut self, _ok: bool) {}
+
     /// Adjusts [crate::Cliprdr] backend capabilities based on capabilities negotiated with a server.
     ///
     /// Called by [crate::Cliprdr] when capability negotiation is finished and server capabilities are

crates/ironrdp-cliprdr/src/lib.rs

@@ -619,6 +619,7 @@ impl<R: Role> Cliprdr<R> {
                         info!("Remote accepted format list");
                     }
                 }
+                self.backend.on_format_list_response(true);
             }
             FormatListResponse::Fail => {
                 // [MS-RDPECLIP] 3.1.5.2.4 - The remote rejected our FormatList but the
@@ -645,6 +646,7 @@ impl<R: Role> Cliprdr<R> {
 
                     self.sent_file_contents_requests.clear();
                 }
+                self.backend.on_format_list_response(false);
             }
         }