From 376cf3325a5f4fb6dfbd36ea4b55ab0d03bc5c6f Mon Sep 17 00:00:00 2001
From: aiongg <aiongtaigi@gmail.com>
Date: Fri, 30 Oct 2026 21:24:39 +0000
Subject: [PATCH] Integration: #1505 leaving parent pages for a page fits its
 spread before centring the page

---
 crates/ui-egui/src/canvas/tests.rs | 14 ++++++++++++++
 crates/ui-egui/src/canvas/view.rs  |  8 +++++---
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/crates/ui-egui/src/canvas/tests.rs b/crates/ui-egui/src/canvas/tests.rs
index f36269479..7d89a24a8 100644
--- a/crates/ui-egui/src/canvas/tests.rs
+++ b/crates/ui-egui/src/canvas/tests.rs
@@ -2869,3 +2869,17 @@ fn table_cells_show_their_hidden_characters() {
     let last = marks.last().unwrap();
     assert_eq!((last.0, last.1), (designcraft_geom::Point::new(frag.rect.x1 + 1.0, frag.rect.y1), "¶"));
 }
+
+#[test]
+fn leaving_parent_editing_for_the_left_page_of_a_spread_keeps_that_page_selected() {
+    let mut app = DesignApp::new(designcraft_engine::Session::new(), crate::Services::default());
+    app.run("file.new", json!({"pages": 4, "facingPages": true})).unwrap();
+    let mut h = harness(app);
+    h.state_mut().run("layout.parents.edit", json!({"on": true, "parent": "A-Parent"})).unwrap();
+    h.run_steps(2);
+    let b = page_box(h.state()).unwrap();
+    // Page 2 is the left page of the second spread.
+    page_box_go(h.state_mut(), &b, 1);
+    h.run_steps(3);
+    assert_eq!(current_page(h.state()), Some(1));
+}
diff --git a/crates/ui-egui/src/canvas/view.rs b/crates/ui-egui/src/canvas/view.rs
index b679923d2..2ba0876a1 100644
--- a/crates/ui-egui/src/canvas/view.rs
+++ b/crates/ui-egui/src/canvas/view.rs
@@ -188,9 +188,11 @@ pub fn page_box_go(app: &mut DesignApp, b: &PageBox, i: usize) {
     if i < b.pages {
         if app.session.active().is_some_and(|st| st.editing_parents) {
             let _ = app.run("layout.parents.edit", serde_json::json!({"on": false}));
-            // The canvas refits to the page's spread once it is centred.
-            if let Some(v) = app.view_mut() {
-                v.fitted = false;
+            // Fit the page's spread first, then centre the page: a later refit would centre the
+            // spread, and the page box would then show its other page.
+            let spread = app.session.active().and_then(|st| st.doc.page_loc(i)).map(|(si, _)| SpreadRef::Doc(si));
+            if let Some(r) = spread {
+                show_spread(app, r);
             }
         }
         go_to_page(app, i);