Contextual External Reference ribbon tab

Shown and brought forward while only xrefs are selected: Edit Reference
In-Place, Open Reference, Create Clipping Boundary, Remove Clipping and
External References.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/commands/pdf_underlay.rs

@@ -20,9 +20,31 @@ impl OpenCADStudio {
         out
     }
 
-    /// Show the tab while only PDF underlays are selected.
+    /// The selected xrefs, or nothing when anything else is selected.
+    pub(in crate::app) fn selected_xrefs(&self, i: usize) -> Vec<codec::Handle> {
+        let doc = &self.tabs[i].scene.document;
+        let mut out = Vec::new();
+        for (handle, entity) in self.tabs[i].scene.selected_entities() {
+            let xref = match entity {
+                codec::EntityType::Insert(ins) => doc
+                    .block_records
+                    .get(&ins.block_name)
+                    .is_some_and(|br| br.flags.is_xref || br.flags.is_xref_overlay),
+                _ => false,
+            };
+            if !xref {
+                return Vec::new();
+            }
+            out.push(handle);
+        }
+        out
+    }
+
+    /// Show the PDF Underlay tab while only PDF underlays are selected, the
+    /// External Reference tab while only xrefs are.
     pub(in crate::app) fn sync_underlay_tab(&mut self) {
         let i = self.active_tab;
+        let xref = !self.tabs[i].is_start && !self.selected_xrefs(i).is_empty();
         let context = if self.tabs[i].is_start {
             None
         } else {
@@ -36,7 +58,7 @@ impl OpenCADStudio {
                 )
             })
         };
-        self.ribbon.set_underlay_context(context);
+        self.ribbon.set_underlay_context(context, xref);
     }
 
     /// One undo step that edits every selected PDF underlay.
@@ -127,6 +149,41 @@ impl OpenCADStudio {
                 self.tabs[i].scene.reseed_underlays();
                 self.sync_underlay_tab();
             }
+            // External Reference tab: the selected xrefs.
+            "_XREFEDIT" | "_XREFOPEN" => {
+                let Some(&handle) = self.selected_xrefs(i).first() else {
+                    return Some(Task::none());
+                };
+                self.tabs[i].scene.deselect_all();
+                self.tabs[i].scene.select_entity(handle, true);
+                let command = if cmd == "_XREFEDIT" { "REFEDIT" } else { "XOPEN" };
+                return Some(self.dispatch_command(command));
+            }
+            "_XREFCLIP" => {
+                use crate::command::CadCommand;
+                let inserts = self.selected_xrefs(i);
+                if inserts.is_empty() {
+                    return Some(Task::none());
+                }
+                let clipped = inserts.iter().any(|h| {
+                    crate::scene::pick::xclip::filter_handle(&self.tabs[i].scene.document, *h).is_some()
+                });
+                let (command, first) =
+                    crate::modules::insert::xclip::XclipCommand::start_new_boundary(inserts, clipped);
+                if let crate::command::CmdResult::ReportMeasurement(text) = first {
+                    for line in text.lines() {
+                        self.command_line.push_output(line);
+                    }
+                }
+                self.command_line.push_info(&command.prompt());
+                self.tabs[i].active_cmd = Some(Box::new(command));
+            }
+            "_XREFUNCLIP" => {
+                let inserts = self.selected_xrefs(i);
+                if !inserts.is_empty() {
+                    self.apply_xclip(i, inserts, crate::modules::insert::xclip::XclipAction::Delete);
+                }
+            }
             "_PDFULUNCLIP" => {
                 self.edit_selected_underlays(i, "PDFCLIP", |u| {
                     u.clip_boundary_vertices.clear();