Expand replaces Widen: fill the window in both directions

From the development repository at 3f1da52.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_end_to_end.py

@@ -1418,23 +1418,26 @@ class EndToEndTest(unittest.TestCase):
         self.assertEqual(placed["placed"]["y"], upward["origin"][1] + 50)
         self.assertEqual(placed["placed"]["x"], upward["origin"][0] + (upward["page"]["width"] - 300) // 2)
 
-        # Widen on a page that writing has grown on one side: the page
-        # comes out as wide as the window, measured from the page's own
-        # edges, not the sheet's (Andy, 2026-10-08).
+        # Expand on a page that writing has grown on one side: the page
+        # comes out as wide and as tall as the window, measured from the
+        # page's own edges, not the sheet's (Andy, 2026-10-08, 2026-10-11).
         firefox.run("""
             document.getElementById('desk').dispatchEvent(new WheelEvent('wheel',
               {deltaY: 100, ctrlKey: true, clientX: 300, clientY: 300, bubbles: true, cancelable: true}));
         """)
-        firefox.run("document.getElementById('zoom_widen').click();")
-        widened = self.wait_until(lambda s: s["page"]["width"] > grown["page"]["width"], "the page to widen")
+        firefox.run("document.getElementById('zoom_expand').click();")
+        self.wait_until(lambda s: s["page"]["width"] > grown["page"]["width"]
+                        and s["page"]["height"] > grown["page"]["height"], "the page to expand")
         measured = firefox.run("""
-            const r = window.kokkoja.renderer;
             const desk = document.getElementById('desk');
             const style = getComputedStyle(desk);
-            const room = desk.offsetWidth - parseFloat(style.paddingLeft) - parseFloat(style.paddingRight);
-            return {page: document.getElementById('page').getBoundingClientRect().width, room};
+            const page = document.getElementById('page').getBoundingClientRect();
+            return {width: page.width, height: page.height,
+                    room: desk.offsetWidth - parseFloat(style.paddingLeft) - parseFloat(style.paddingRight),
+                    roomHeight: desk.offsetHeight - parseFloat(style.paddingTop) - parseFloat(style.paddingBottom)};
         """)
-        self.assertAlmostEqual(measured["page"], measured["room"], delta=1)
+        self.assertAlmostEqual(measured["width"], measured["room"], delta=1)
+        self.assertAlmostEqual(measured["height"], measured["roomHeight"], delta=1)
 
         # The writer's tab is closed for the next test; the host's is cleared.
         firefox.switch_to(guest_tab)
@@ -1654,8 +1657,8 @@ class EndToEndTest(unittest.TestCase):
         time.sleep(0.5)
         self.assertEqual(firefox.run("return window.kokkoja.renderer.cssPixelsPerUnit;"), host_scale)
 
-        # Widen makes the sheet itself wider, for everyone, until it fills
-        # the window at this zoom; the scale and what is in view stay.
+        # Expand makes the sheet fill the window, for everyone, at this
+        # zoom, in both directions; the scale and what is in view stay.
         firefox.run("""
             document.getElementById('desk').dispatchEvent(new WheelEvent('wheel',
               {deltaY: 100, ctrlKey: true, clientX: 300, clientY: 300, bubbles: true, cancelable: true}));
@@ -1666,29 +1669,36 @@ class EndToEndTest(unittest.TestCase):
             return [Math.round(b.left), Math.round(b.top), Math.round(b.width)];
         """)
         box_before = image_box()
-        firefox.run("document.getElementById('zoom_widen').click();")
-        widened = zoom()
-        # The sheet grew equally on both sides: nothing on it moved on the screen.
+        firefox.run("document.getElementById('zoom_expand').click();")
+        expanded = zoom()
+        # The sheet grew equally on every side: nothing on it moved on screen.
         self.assertEqual(image_box(), box_before)
         self.assertLess(firefox.run("return window.kokkoja.session.page.baseLeft;"), 0)
-        desk_width = firefox.run("""
+        self.assertLess(firefox.run("return window.kokkoja.session.page.baseTop;"), 0)
+        room = firefox.run("""
             const desk = document.getElementById('desk');
             const style = getComputedStyle(desk);
-            return desk.offsetWidth - parseFloat(style.paddingLeft) - parseFloat(style.paddingRight);
+            return {width: desk.offsetWidth - parseFloat(style.paddingLeft) - parseFloat(style.paddingRight),
+                    height: desk.offsetHeight - parseFloat(style.paddingTop) - parseFloat(style.paddingBottom)};
         """)
-        self.assertAlmostEqual(widened["width"], desk_width, delta=1)
-        self.assertEqual(widened["zoom"], smaller["zoom"])
+        page_box = firefox.run("""
+            const b = document.getElementById('page').getBoundingClientRect();
+            return {width: b.width, height: b.height};
+        """)
+        self.assertAlmostEqual(page_box["width"], room["width"], delta=1)
+        self.assertAlmostEqual(page_box["height"], room["height"], delta=1)
+        self.assertEqual(expanded["zoom"], smaller["zoom"])
         wide_page = self.state()["page"]
         self.assertGreater(wide_page["width"], teacher["page"]["width"])
-        self.assertEqual(wide_page["height"], teacher["page"]["height"])
+        self.assertGreater(wide_page["height"], teacher["page"]["height"])
         firefox.switch_to(student_tab)
-        self.wait_until(lambda s: s["page"] == wide_page, "the wider page to reach the student")
-        self.assertTrue(firefox.run("return document.getElementById('zoom_widen').hidden;"))
+        self.wait_until(lambda s: s["page"] == wide_page, "the expanded page to reach the student")
+        self.assertTrue(firefox.run("return document.getElementById('zoom_expand').hidden;"))
         self.assertEqual(firefox.run("return window.kokkoja.session.page.baseLeft;"),
                          -((wide_page["width"] - teacher["page"]["width"]) // 2))
-        # The page file carries the sheet's left edge and reads back with it.
-        widened_file = self.current_page("Student notebook", {}, number=3)
-        self.assertRegex(widened_file, r'data-base="\d+ 2100 -\d+ 0"')
+        # The page file carries the sheet's edges and reads back with them.
+        expanded_file = self.current_page("Student notebook", {}, number=3)
+        self.assertRegex(expanded_file, r'data-base="\d+ \d+ -\d+ -\d+"')
         firefox.switch_to(teacher_tab)
 
         # Shrink makes the sheet just large enough for what is on it, with
@@ -1725,15 +1735,15 @@ class EndToEndTest(unittest.TestCase):
         firefox.run("document.getElementById('zoom_sheet').click();")
         sheet_scale = firefox.run("return window.kokkoja.renderer.cssPixelsPerUnit;")
         self.assertLess(sheet_scale, fitted_scale)
-        self.assertAlmostEqual(sheet_scale, min(desk_width / 2970, firefox.run("""
+        self.assertAlmostEqual(sheet_scale, min(room["width"] / 2970, firefox.run("""
             const desk = document.getElementById('desk');
             const style = getComputedStyle(desk);
             return desk.offsetHeight - parseFloat(style.paddingTop) - parseFloat(style.paddingBottom);
         """) / 2100), places=4)
-        # Widened again, from the shrunk sheet, for the room the rest needs.
+        # Expanded again, from the shrunk sheet, for the room the rest needs.
         firefox.run("document.getElementById('zoom_fit').click();")
-        firefox.run("document.getElementById('zoom_widen').click();")
-        self.wait_until(lambda s: s["page"]["width"] > shrunk_page["page"]["width"], "the page widened again")
+        firefox.run("document.getElementById('zoom_expand').click();")
+        self.wait_until(lambda s: s["page"]["width"] > shrunk_page["page"]["width"], "the page expanded again")
         firefox.run("document.getElementById('zoom_fit').click();")
         teacher = self.state()