Keep the selected guide selected when an earlier guide is removed (#418)

crates/engine/src/cmd/page.rs

@@ -160,8 +160,11 @@ pub fn specs() -> Vec<CommandSpec> {
             }
             guides.remove(k);
             let ds = s.ds_mut()?;
-            if ds.guide == Some((owner, k)) {
-                ds.guide = None;
+            match ds.guide {
+                Some((o, i)) if o == owner && i == k => ds.guide = None,
+                // A later guide of the same owner moves up one place; keep the selection on it.
+                Some((o, i)) if o == owner && i > k => ds.guide = Some((o, i - 1)),
+                _ => {}
             }
             ok()
         }),

crates/engine/src/view_behaviour_tests.rs

@@ -456,6 +456,23 @@ fn a_selected_guide_is_deleted_and_nudged_with_the_keyboard() {
     assert!(s.execute("guide.select", &json!({"index": 7})).is_err(), "only an existing guide can be selected");
 }
 
+#[test]
+fn removing_an_earlier_guide_keeps_the_selected_guide() {
+    let mut s = Session::new();
+    for offset in [100, 200, 300] {
+        ex(&mut s, "guide.add", json!({"vertical": true, "offset": offset}));
+    }
+    let page = s.page().unwrap();
+    ex(&mut s, "guide.select", json!({"index": 1}));
+    ex(&mut s, "guide.remove", json!({"index": 0}));
+    assert_eq!(s.ds().unwrap().selected_guide(), Some((page, 0)), "the guide at 200 stays selected at its new index");
+    assert!(s.tool_key("ArrowRight", false, false, false).unwrap());
+    assert_eq!(guide_list(&s, page), vec![(true, 201.0), (true, 300.0)], "the arrow nudges the selected guide, not its neighbour");
+    // A later guide leaves the selection alone.
+    ex(&mut s, "guide.remove", json!({"index": 1}));
+    assert_eq!(s.ds().unwrap().selected_guide(), Some((page, 0)));
+}
+
 #[test]
 fn guides_snap_and_measure() {
     let mut s = Session::new();

docs/mcp.md

@@ -1383,7 +1383,8 @@ siblings and the frame's edges) along those axes, keeping whole pixels in the fr
 
 `guide.select {index, frame? | page?}` selects a guide (and deselects the layers; `{}` deselects
 it), as clicking one does in the app; `guide.remove {}` without an index removes the selected one
-(the context menu's Remove guide). While a guide is selected and no layer is, Delete removes it,
+(the context menu's Remove guide), and removing another guide keeps the selected one selected.
+While a guide is selected and no layer is, Delete removes it,
 the arrows across it nudge it (Shift: the big nudge) and Escape deselects it. In the app, a guide
 dragged out of a ruler and dropped on a frame becomes the guide of the top-level frame there, along
 the frame's axis nearer the ruler's; Alt-dragging a guide drops a copy, and holding Alt while