feat(insert): add initial PDF underlay attachment

src/app/commands/blocks.rs

@@ -515,11 +515,13 @@ impl OpenCADStudio {
                 self.open_attedit_dialog();
             }
 
+            "PDFATTACH" => {
+                return Some(Task::done(Message::PdfAttachPick));
+            }
             "XATTACH" => {
                 // Launch the file picker; XAttachPickResult will start the command.
                 return Some(Task::done(Message::XAttachPick));
             }
-
             cmd if cmd == "WBLOCK" || cmd == "WB" || cmd.starts_with("WBLOCK ") => {
                 let arg = cmd.splitn(2, ' ').nth(1).unwrap_or("").trim();
                 if arg.is_empty() {

src/app/mod.rs

@@ -3189,6 +3189,12 @@ pub enum Message {
     ImagePick,
     /// Result of the image file picker + pixel dimension decode.
     ImagePickResult(Result<(std::path::PathBuf, u32, u32), String>),
+    // ── PDF Underlay ──────────────────────────────────────────────────────
+    /// Open file-picker dialog for PDFATTACH command (async).
+    PdfAttachPick,
+    /// Result of the PDFATTACH file picker.
+    PdfAttachPickResult(Result<std::path::PathBuf, String>),
+
     // ── XREF ──────────────────────────────────────────────────────────────
     /// Open file-picker dialog for XATTACH command (async).
     XAttachPick,

src/app/update/mod.rs

@@ -902,7 +902,60 @@ impl OpenCADStudio {
                 }
                 Task::none()
             }
+            Message::PdfAttachPick => Task::perform(
+                async {
+                    let handle = crate::sys::file_dialog()
+                        .set_title("Select PDF Underlay")
+                        .add_filter("PDF Files", &["pdf", "PDF"])
+                        .pick_file()
+                        .await;
 
+                    match handle {
+                        Some(h) => Ok(crate::sys::handle_path(&h)),
+                        None => Err("Cancelled".to_string()),
+                    }
+                },
+                Message::PdfAttachPickResult,
+            ),
+
+            Message::PdfAttachPickResult(Ok(path)) => {
+                use acadrust::objects::{ObjectType, UnderlayDefinition};
+                use crate::command::CadCommand;
+                use crate::modules::insert::pdf_attach::PdfAttachCommand;
+
+                let i = self.active_tab;
+                let path_str = path.to_string_lossy().into_owned();
+
+                let definition_handle = self.tabs[i].scene.document.allocate_handle();
+
+                let mut definition = UnderlayDefinition::pdf(&path_str, "1");
+                definition.handle = definition_handle;
+
+                self.tabs[i]
+                    .scene
+                    .document
+                    .objects
+                    .insert(
+                        definition_handle,
+                        ObjectType::UnderlayDefinition(definition),
+                    );
+
+                let cmd = PdfAttachCommand::new(definition_handle);
+
+                self.command_line.push_info(&cmd.prompt());
+                self.tabs[i].active_cmd = Some(Box::new(cmd));
+
+                Task::none()
+            }
+
+            Message::PdfAttachPickResult(Err(e)) => {
+                if e != "Cancelled" {
+                    self.command_line
+                        .push_error(crate::tf!("PDFATTACH: {e}").as_ref());
+                }
+
+                Task::none()
+            }
             Message::XAttachPick => Task::perform(
                 async {
                     let handle = crate::sys::file_dialog()