Make Widget.is_on_screen read the last published geometry only

evidence/committed-screen-membership-20261007/README.md

@@ -0,0 +1,24 @@
+# Committed screen membership
+
+Widget.is_on_screen declares last-screen-update membership. It previously used
+Compositor.find_widget, which acquires missing offscreen paths and can arrange
+again every time a hidden widget asks. It now consumes the original committed
+map via _get_published_geometry. No membership store or negative cache is added.
+Region, virtual_region and focus ordering retain their original acquisition.
+The selected capture reader remains unchanged; screen membership describes the
+committed screen, not a temporary body-render scope.
+
+Native automatic_refresh and Toad project/path/recovery status consumers are
+covered by the existing property. Custom overrides remain independent. The Toad
+throbber already explicitly selects clipped visible membership; that stricter
+paint eligibility remains untouched. The source census is in source.json.
+
+One actual headless App control passed in 0.37 seconds: visible, offscreen,
+hidden and detached cases, 120 reads with zero _arrange_root calls, followed by
+successful explicit offscreen acquisition. Original native layout and widget
+owners were used. No provider, package, public runtime or profile rerun.
+
+This removes status-query arrangement. It does not fix repeated unsatisfied
+focus geometry requests, prove the recorded mount delay solved, or establish
+an installed latency improvement. Child cardinality is already constant-time;
+style invalidation retains custom renderer dependencies.

evidence/committed-screen-membership-20261007/check.log

@@ -0,0 +1,2 @@
+.                                                                        [100%]
+1 passed in 0.37s

evidence/committed-screen-membership-20261007/source.json

@@ -0,0 +1,144 @@
+{
+  "native": {
+    "head": "6e950babe0808e9955d29d9f655d82dbc0be383c",
+    "modules": 723,
+    "omissions": [],
+    "sites": [
+      [
+        "src/textual/_compositor.py",
+        1489,
+        "declaration",
+        "_get_published_geometry"
+      ],
+      [
+        "src/textual/_compositor.py",
+        1487,
+        "self._get_published_geometry"
+      ],
+      [
+        "src/textual/_compositor.py",
+        1818,
+        "self._get_published_geometry"
+      ],
+      [
+        "src/textual/dom.py",
+        622,
+        "declaration",
+        "is_on_screen"
+      ],
+      [
+        "src/textual/dom.py",
+        626,
+        "declaration",
+        "automatic_refresh"
+      ],
+      [
+        "src/textual/dom.py",
+        634,
+        "self.is_on_screen"
+      ],
+      [
+        "src/textual/widget.py",
+        2708,
+        "declaration",
+        "is_on_screen"
+      ],
+      [
+        "tests/test_auto_refresh.py",
+        17,
+        "declaration",
+        "automatic_refresh"
+      ]
+    ]
+  },
+  "toad": {
+    "head": "aef46ff5d3069ae5afeefb9139d3943ffbcbe74c",
+    "modules": 691,
+    "omissions": [],
+    "sites": [
+      [
+        "src/toad/project_path_owner.py",
+        19,
+        "widget.is_on_screen"
+      ],
+      [
+        "src/toad/widgets/conversation.py",
+        171,
+        "declaration",
+        "automatic_refresh"
+      ],
+      [
+        "src/toad/widgets/goal_bar.py",
+        47,
+        "declaration",
+        "automatic_refresh"
+      ],
+      [
+        "src/toad/widgets/path_search.py",
+        288,
+        "self.is_on_screen"
+      ],
+      [
+        "src/toad/widgets/project_directory_tree.py",
+        111,
+        "self.is_on_screen"
+      ],
+      [
+        "src/toad/widgets/project_directory_tree.py",
+        116,
+        "self.is_on_screen"
+      ],
+      [
+        "src/toad/widgets/recovery_view.py",
+        56,
+        "self.is_on_screen"
+      ],
+      [
+        "src/toad/widgets/throbber.py",
+        118,
+        "declaration",
+        "automatic_refresh"
+      ],
+      [
+        "tests/declared_target_actions_installed_pilot.py",
+        284,
+        "endpoint.is_on_screen"
+      ],
+      [
+        "tests/declared_target_actions_installed_pilot.py",
+        284,
+        "anchor.is_on_screen"
+      ],
+      [
+        "tests/declared_target_actions_installed_pilot.py",
+        293,
+        "anchor.is_on_screen"
+      ],
+      [
+        "tests/declared_target_actions_installed_pilot.py",
+        294,
+        "endpoint.is_on_screen"
+      ],
+      [
+        "tests/declared_target_actions_installed_pilot.py",
+        208,
+        "row.is_on_screen"
+      ],
+      [
+        "tests/declared_target_actions_installed_pilot.py",
+        157,
+        "row.is_on_screen"
+      ],
+      [
+        "tests/sidebar_selected_targets_pilot.py",
+        142,
+        "endpoint.is_on_screen"
+      ],
+      [
+        "tests/sidebar_selected_targets_pilot.py",
+        142,
+        "anchor.is_on_screen"
+      ]
+    ]
+  }
+}

src/textual/widget.py

@@ -2706,12 +2706,15 @@ def _relative_children_height(self) -> tuple[bool, bool]:
 
     @property
     def is_on_screen(self) -> bool:
-        """Check if the node was displayed in the last screen update."""
+        """Check membership in the last committed screen geometry.
+
+        A status read must not acquire omitted/offscreen layout paths. Explicit
+        position readers still request those paths through ``find_widget``.
+        """
         try:
-            self.screen.find_widget(self)
-        except (NoScreen, errors.NoWidget):
+            return self.screen._compositor._get_published_geometry(self) is not None
+        except NoScreen:
             return False
-        return True
 
     def _resolve_extrema(
         self,

tests/test_compositor.py

@@ -391,3 +391,46 @@ def compose(self):
         with patch.object(compositor, "_get_renders", lambda crop=None, render_regions=None, *, widgets: original(crop, widgets=widgets)):
             expected = compositor.render_strips()
         assert actual == expected
+
+
+async def test_screen_membership_reads_do_not_acquire_geometry():
+    """Status is the committed scene; explicit position reads may widen it."""
+    import cProfile
+    from textual.containers import VerticalScroll
+
+    class MembershipApp(App):
+        CSS = "VerticalScroll { height: 3; } Static { height: 1; } #hidden { display: none; }"
+
+        def compose(self):
+            yield VerticalScroll(*(Static(str(index), id=f"row-{index}")
+                                   for index in range(30)))
+            yield Static("hidden", id="hidden")
+
+    app = MembershipApp()
+    detached = Static("detached")
+    assert not detached.is_on_screen
+    async with app.run_test(size=(30, 10)) as pilot:
+        await pilot.pause()
+        compositor = app.screen._compositor
+        compositor.reflow_visible(app.screen, app.screen.size, retain_geometry=())
+        assert compositor._full_map_invalidated
+        hidden = app.query_one("#hidden")
+        last = app.query_one("#row-29")
+        first = app.query_one("#row-0")
+        scene = compositor._published_map
+        assert first in scene and last not in scene and hidden not in scene
+        profile = cProfile.Profile()
+        with profile:
+            for _ in range(40):
+                assert first.is_on_screen
+                assert not last.is_on_screen
+                assert not hidden.is_on_screen
+        assert compositor._published_map is scene
+        assert compositor._full_map_invalidated
+        assert not any(entry.code.co_name == "_arrange_root"
+                       for entry in profile.getstats()
+                       if not isinstance(entry.code, str))
+        # A genuine geometry demand retains the offscreen path in this scene.
+        assert compositor.find_widget(last).virtual_region.y > 0
+        assert last.is_on_screen
+        assert not hidden.is_on_screen