docs: compare cold grid and translated pan rendering alternatives

crates/oa-desktop/src/allocation_drag.rs

@@ -210,7 +210,6 @@ impl SemanticPlan {
     pub fn project(&self) -> &Project {
         &self.candidate
     }
-    #[cfg(test)]
     pub fn index(&self) -> &ViewIndex {
         &self.index
     }
@@ -485,6 +484,57 @@ pub struct PresentationContext {
     pub target: Option<TargetPresentation>,
 }
 
+impl PresentationContext {
+    fn header_visible(self, header: Rect, outgoing: bool) -> bool {
+        if !outgoing {
+            return self.viewport.contains(header);
+        }
+        // Leaving a performer must not require fitting the entire work card
+        // inside the camera. Retain a 24px grab region so the result stays
+        // directly reachable; geometry/model admission is independent.
+        let width = (header.position.x + header.size.width)
+            .min(self.viewport.position.x + self.viewport.size.width)
+            - header.position.x.max(self.viewport.position.x);
+        let height = (header.position.y + header.size.height)
+            .min(self.viewport.position.y + self.viewport.size.height)
+            - header.position.y.max(self.viewport.position.y);
+        width * self.zoom >= 24. && height * self.zoom >= 24.
+    }
+}
+
+#[test]
+fn outgoing_header_retains_a_grab_region_without_requiring_full_camera_containment() {
+    let context = PresentationContext {
+        viewport: Rect {
+            position: Position { x: 0., y: 0. },
+            size: Size {
+                width: 800.,
+                height: 400.,
+            },
+        },
+        zoom: 0.75,
+        target: None,
+    };
+    let mut header = Rect {
+        position: Position { x: -100., y: 30. },
+        size: Size {
+            width: 224.,
+            height: 62.,
+        },
+    };
+    assert!(context.header_visible(header, true));
+    assert!(!context.header_visible(header, false));
+    header.position.x = -192.; // exactly 32 world pixels = 24 logical pixels
+    assert!(context.header_visible(header, true));
+    header.position.x -= 1.;
+    assert!(!context.header_visible(header, true));
+    header.position.x = 0.;
+    header.position.y = 368.;
+    assert!(context.header_visible(header, true));
+    header.position.y += 1.;
+    assert!(!context.header_visible(header, true));
+}
+
 #[derive(Debug)]
 pub struct PlacementPlan {
     pub diagram: Diagram,
@@ -496,8 +546,8 @@ pub struct PlacementPlan {
     commands: Vec<Command>,
 }
 
-/// `requested` is the original selected placement position plus pointer motion
-/// in the frozen transform (therefore preserving the press offset). Snap only
+/// `requested` preserves the frozen pointer offset unless the caller proposes
+/// bounded outward clearance for an outgoing drop. Snap only
 /// this root; apply the resulting identical delta to captured Q and its routes.
 /// No whole Project clone, validator or semantic ViewIndex rebuild occurs here.
 pub fn place(
@@ -577,7 +627,7 @@ pub fn place(
             height: selected.size.height.min(62.),
         },
     };
-    if !presentation.viewport.contains(header) {
+    if !presentation.header_visible(header, plan.destination == Destination::OutsidePerformers) {
         return Err(Refusal::LayoutRequired(
             "Make room or adjust the view, then drag again.".into(),
         ));

crates/oa-desktop/src/allocation_drag/arrange.rs

@@ -188,7 +188,7 @@ pub fn place(
     };
     geometry::check_rigid(&plan.before_expanded, &expanded, &plan.placements, delta)?;
     scenes?;
-    geometry::check_headers(&view, &plan.selected, presentation.viewport)?;
+    geometry::check_headers(&view, &plan.selected, presentation, false)?;
     Ok(PlacementPlan {
         diagram,
         view,

crates/oa-desktop/src/allocation_drag/assignment.rs

@@ -398,7 +398,12 @@ pub fn place(
         &expanded,
     )?;
     geometry::check_rigid(&scope.0.before_expanded, &expanded, scope.affected(), delta)?;
-    geometry::check_headers(&view, scope.selected(), presentation.viewport)?;
+    geometry::check_headers(
+        &view,
+        scope.selected(),
+        presentation,
+        plan.destination == Destination::OutsidePerformers,
+    )?;
     Ok(PlacementPlan {
         diagram,
         view,

crates/oa-desktop/src/allocation_drag/geometry.rs

@@ -170,7 +170,8 @@ pub(super) fn check_rigid(
 pub(super) fn check_headers(
     view: &ProjectedView,
     selected: &BTreeMap<Id, Id>,
-    viewport: Rect,
+    presentation: PresentationContext,
+    outgoing: bool,
 ) -> Result<(), Refusal> {
     for (id, element) in selected {
         let node = view
@@ -185,7 +186,7 @@ pub(super) fn check_headers(
                 height: node.size.height.min(62.),
             },
         };
-        if !viewport.contains(header) {
+        if !presentation.header_visible(header, outgoing) {
             return Err(Refusal::LayoutRequired(
                 "Make room or adjust the view, then drag again.".into(),
             ));

crates/oa-desktop/src/app/allocation_drag.rs

@@ -14,6 +14,8 @@ use std::{
     sync::Arc,
 };
 
+mod clearance;
+
 pub const FINISH_EDIT: &str =
     "Finish or cancel the current edit before selecting or moving elements.";
 
@@ -56,6 +58,7 @@ pub struct Target {
 #[derive(Debug, Clone)]
 pub struct Frozen {
     pub targets: Vec<Target>,
+    pub moving: Vec<Rectangle>,
     cards: Vec<Rectangle>,
     controls: Vec<Rectangle>,
     edges: Vec<(Point, Point)>,
@@ -82,14 +85,16 @@ impl Frozen {
     ) -> Self {
         let mut targets = Vec::new();
         let mut cards = Vec::new();
+        let mut moving = Vec::new();
         for n in &view.nodes {
-            if affected.contains_key(&n.id) {
-                continue;
-            }
             let region = Rectangle::new(
                 Point::new(n.position.x, n.position.y),
                 iced::Size::new(n.size.width, n.size.height),
             );
+            if affected.contains_key(&n.id) {
+                moving.push(region);
+                continue;
+            }
             let Some(e) = project.elements.get(&n.element) else {
                 cards.push(region);
                 continue;
@@ -172,6 +177,7 @@ impl Frozen {
         }
         Self {
             targets,
+            moving,
             cards,
             controls,
             edges,
@@ -407,7 +413,6 @@ impl Candidate {
             Self::Performers(p) => &p.accepted,
         }
     }
-    #[cfg(test)]
     pub fn index(&self) -> &view_options::ViewIndex {
         match self {
             Self::Singleton(p) => p.index(),
@@ -525,6 +530,8 @@ pub(crate) struct Feedback {
     pub inspection_targets: Vec<usize>,
     pub text: String,
     pub refused: bool,
+    /// Pointer-following outline only; it never authorizes a model change.
+    pub ghost_delta: Option<Vector>,
 }
 impl Feedback {
     pub fn inspection_identity(&self) -> String {
@@ -1055,7 +1062,26 @@ impl App {
                         viewport: stamp.viewport(), zoom: stamp.zoom,
                         target: target.map(|i| plan::TargetPresentation { placement: active.frozen.as_ref().unwrap().targets[i].placement }),
                     };
-                    let placed = candidate.place(requested, presentation).map_err(|r| refusal(&r))?;
+                    let exact = candidate.place(requested, presentation);
+                    let placed = if destination == plan::Destination::OutsidePerformers
+                        && matches!(&exact, Err(plan::Refusal::LayoutRequired(_)))
+                    {
+                        let affected = match &active.prepared {
+                            Prepared::Singleton(scope) => Some(&scope.placements),
+                            Prepared::Assignment(scope) => Some(scope.affected()),
+                            _ => None,
+                        };
+                        affected.and_then(|affected| {
+                            clearance::requests(
+                                (self.project(), self.document.view_index()),
+                                (candidate.project(), candidate.index()), stamp.context.diagram,
+                                affected, *anchor, requested,
+                                (stamp.world(press.start), stamp.world(pointer.unwrap())),
+                            ).into_iter().find_map(|position| candidate.place(position, presentation).ok())
+                        }).map_or(exact, Ok)
+                    } else {
+                        exact
+                    }.map_err(|r| refusal(&r))?;
                     let label = candidate.label();
                     if release {
                         if let Some(command) = candidate.finish(self.project(), &placed).map_err(|r| refusal(&r))? {
@@ -1082,6 +1108,14 @@ impl App {
         } else {
             let inspection_targets = active.inspection_targets.clone();
             let frozen = active.frozen.clone();
+            // A rejected intermediate position is not a return gesture. Keep the
+            // last admitted scene and show current motion separately; release
+            // always recomputes admission and never commits this retained view.
+            if refused && in_bounds && preview.is_none() {
+                preview = self.allocation_drag.preview.take();
+            }
+            let ghost_delta = (refused && in_bounds)
+                .then(|| (pointer.unwrap() - press.start) * (1. / stamp.zoom));
             self.allocation_drag.active = Some(active);
             self.allocation_drag.preview = preview;
             self.allocation_drag.feedback = Some(Feedback {
@@ -1092,6 +1126,7 @@ impl App {
                 inspection_targets,
                 text,
                 refused,
+                ghost_delta,
             });
         }
     }

crates/oa-desktop/src/app/allocation_drag/clearance.rs

@@ -0,0 +1,595 @@
+//! Bounded outgoing clearance proposals. The ordinary placement and semantic
+//! validators still decide whether any proposal may be previewed or committed.
+use iced::Point;
+use oa_core::{Id, NodePlacement, Position, Project, projection, view_options::ViewIndex};
+use std::collections::{BTreeMap, BTreeSet};
+
+const GRID: f32 = 10.;
+const GAP: f32 = 10.;
+
+#[derive(Clone, Copy)]
+struct Bounds {
+    left: f32,
+    top: f32,
+    right: f32,
+    bottom: f32,
+}
+
+impl Bounds {
+    fn node(node: &projection::ProjectedNode) -> Option<Self> {
+        let result = Self {
+            left: node.position.x,
+            top: node.position.y,
+            right: node.position.x + node.size.width,
+            bottom: node.position.y + node.size.height,
+        };
+        ([result.left, result.top, result.right, result.bottom]
+            .iter()
+            .all(|value| value.is_finite())
+            && result.right > result.left
+            && result.bottom > result.top)
+            .then_some(result)
+    }
+
+    fn union(self, other: Self) -> Self {
+        Self {
+            left: self.left.min(other.left),
+            top: self.top.min(other.top),
+            right: self.right.max(other.right),
+            bottom: self.bottom.max(other.bottom),
+        }
+    }
+
+    fn overlaps(self, other: Self) -> bool {
+        self.left < other.right
+            && other.left < self.right
+            && self.top < other.bottom
+            && other.top < self.bottom
+    }
+}
+
+/// Called only after an OutsidePerformers candidate fails ordinary placement.
+/// Coordinates use the frozen world transform. The entire affected footprint
+/// receives one anchor translation; this never moves or packs other cards.
+pub(super) fn requests(
+    accepted: (&Project, &ViewIndex),
+    candidate: (&Project, &ViewIndex),
+    diagram: Id,
+    affected: &BTreeMap<Id, NodePlacement>,
+    anchor: Id,
+    requested: Position,
+    motion: (Point, Point),
+) -> Vec<Position> {
+    let (accepted, accepted_index) = accepted;
+    let (candidate, candidate_index) = candidate;
+    let (start, pointer) = motion;
+    if ![
+        requested.x,
+        requested.y,
+        start.x,
+        start.y,
+        pointer.x,
+        pointer.y,
+    ]
+    .iter()
+    .all(|value| value.is_finite())
+    {
+        return Vec::new();
+    }
+    let (Some(original), Some(base), Some(anchor)) = (
+        accepted.diagrams.get(&diagram),
+        candidate.diagrams.get(&diagram),
+        affected.get(&anchor),
+    ) else {
+        return Vec::new();
+    };
+    let snapped = Position {
+        x: (requested.x / GRID).round() * GRID,
+        y: (requested.y / GRID).round() * GRID,
+    };
+    let delta = Position {
+        x: snapped.x - anchor.position.x,
+        y: snapped.y - anchor.position.y,
+    };
+    let before = projection::project_diagram_with_index(accepted, original, accepted_index);
+    let before_nodes: BTreeMap<_, _> = before.nodes.iter().map(|node| (node.id, node)).collect();
+    let mut sources = BTreeSet::new();
+    for node in before
+        .nodes
+        .iter()
+        .filter(|node| affected.contains_key(&node.id))
+    {
+        let mut parent = node.visual_parent;
+        let mut seen = BTreeSet::new();
+        while let Some(id) = parent {
+            if !seen.insert(id) {
+                return Vec::new();
+            }
+            let Some(node) = before_nodes.get(&id) else {
+                break;
+            };
+            if !affected.contains_key(&id)
+                && accepted
+                    .elements
+                    .get(&node.element)
+                    .is_some_and(|element| element.kind().is_performer())
+            {
+                sources.insert(id);
+            }
+            parent = node.visual_parent;
+        }
+    }
+    if sources.is_empty() {
+        return Vec::new();
+    }
+    // Projection after responsibility removal supplies the former performer's
+    // remaining enclosure, including other allocated work. Projecting the moved
+    // block also includes the full visible descendant enclosure of every root.
+    let mut moved = base.clone();
+    for (id, captured) in affected {
+        let Some(node) = moved.nodes.get_mut(id) else {
+            return Vec::new();
+        };
+        node.position = Position {
+            x: captured.position.x + delta.x,
+            y: captured.position.y + delta.y,
+        };
+        if ![
+            node.position.x,
+            node.position.y,
+            node.size.width,
+            node.size.height,
+        ]
+        .iter()
+        .all(|value| value.is_finite())
+        {
+            return Vec::new();
+        }
+    }
+    let after = projection::project_diagram_with_index(candidate, &moved, candidate_index);
+    let mut footprint: Option<Bounds> = None;
+    for node in after
+        .nodes
+        .iter()
+        .filter(|node| affected.contains_key(&node.id))
+    {
+        let Some(bounds) = Bounds::node(node) else {
+            return Vec::new();
+        };
+        footprint = Some(footprint.map_or(bounds, |previous| previous.union(bounds)));
+    }
+    let Some(footprint) = footprint else {
+        return Vec::new();
+    };
+    let mut overlaps = Vec::new();
+    for node in after.nodes.iter().filter(|node| sources.contains(&node.id)) {
+        let (Some(old), Some(current)) = (Bounds::node(before_nodes[&node.id]), Bounds::node(node))
+        else {
+            return Vec::new();
+        };
+        if footprint.overlaps(current) {
+            overlaps.push((old, current));
+        }
+    }
+    if overlaps.is_empty() {
+        return Vec::new();
+    }
+
+    // Each entry is a half-plane actually crossed by the pointer. At a corner,
+    // prefer the boundary reached first on the press-to-pointer segment. The
+    // direction index is a stable tie-break, independent of placement UUIDs.
+    let mut crossings = [None::<f32>; 4];
+    for (old, _) in &overlaps {
+        for (direction, initial, final_, boundary, outward) in [
+            (
+                0,
+                start.x,
+                pointer.x,
+                old.left,
+                pointer.x < old.left && start.x >= old.left,
+            ),
+            (
+                1,
+                start.x,
+                pointer.x,
+                old.right,
+                pointer.x >= old.right && start.x < old.right,
+            ),
+            (
+                2,
+                start.y,
+                pointer.y,
+                old.top,
+                pointer.y < old.top && start.y >= old.top,
+            ),
+            (
+                3,
+                start.y,
+                pointer.y,
+                old.bottom,
+                pointer.y >= old.bottom && start.y < old.bottom,
+            ),
+        ] {
+            if outward {
+                let fraction = (boundary - initial) / (final_ - initial);
+                if fraction.is_finite() && (0. ..=1.).contains(&fraction) {
+                    crossings[direction] =
+                        Some(crossings[direction].map_or(fraction, |old| old.min(fraction)));
+                }
+            }
+        }
+    }
+    let mut directions: Vec<_> = crossings
+        .into_iter()
+        .enumerate()
+        .filter_map(|(direction, fraction)| fraction.map(|fraction| (direction, fraction)))
+        .collect();
+    directions.sort_by(|a, b| a.1.total_cmp(&b.1).then(a.0.cmp(&b.0)));
+    let mut result = Vec::new();
+    for (direction, _) in directions {
+        let mut corrected = snapped;
+        match direction {
+            0 => {
+                let edge = overlaps
+                    .iter()
+                    .map(|(_, current)| current.left)
+                    .fold(f32::INFINITY, f32::min);
+                corrected.x = ((snapped.x + edge - GAP - footprint.right) / GRID).floor() * GRID;
+            }
+            1 => {
+                let edge = overlaps
+                    .iter()
+                    .map(|(_, current)| current.right)
+                    .fold(f32::NEG_INFINITY, f32::max);
+                corrected.x = ((snapped.x + edge + GAP - footprint.left) / GRID).ceil() * GRID;
+            }
+            2 => {
+                let edge = overlaps
+                    .iter()
+                    .map(|(_, current)| current.top)
+                    .fold(f32::INFINITY, f32::min);
+                corrected.y = ((snapped.y + edge - GAP - footprint.bottom) / GRID).floor() * GRID;
+            }
+            3 => {
+                let edge = overlaps
+                    .iter()
+                    .map(|(_, current)| current.bottom)
+                    .fold(f32::NEG_INFINITY, f32::max);
+                corrected.y = ((snapped.y + edge + GAP - footprint.top) / GRID).ceil() * GRID;
+            }
+            _ => unreachable!(),
+        }
+        if corrected.x.is_finite() && corrected.y.is_finite() && !result.contains(&corrected) {
+            result.push(corrected);
+        }
+    }
+    result
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::allocation_drag as plan;
+    use oa_core::{Kind, Layer, ProjectionKind, RelationKind, Size};
+
+    struct Fixture {
+        project: Project,
+        diagram: Id,
+        performer: Id,
+        work: Id,
+        node: Id,
+    }
+
+    fn xy(x: f32, y: f32) -> Position {
+        Position { x, y }
+    }
+
+    fn fixture(layer: Layer) -> Fixture {
+        let mut project = Project::empty();
+        let (performer, work) = match layer {
+            Layer::Oa => (Kind::Entity, Kind::Activity),
+            Layer::Sa => (Kind::System, Kind::Function),
+        };
+        let performer = project
+            .add_element(performer, layer, "Performer", None)
+            .unwrap();
+        let work = project.add_element(work, layer, "Work", None).unwrap();
+        let diagram = project.ensure_diagram(layer);
+        project.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Allocation;
+        let performer = project.place(diagram, performer, xy(100., 100.));
+        project
+            .diagrams
+            .get_mut(&diagram)
+            .unwrap()
+            .nodes
+            .get_mut(&performer)
+            .unwrap()
+            .size = Size {
+            width: 400.,
+            height: 250.,
+        };
+        let node = project.place(diagram, work, xy(160., 180.));
+        let owner = project.diagrams[&diagram].nodes[&performer].element;
+        project.relate(RelationKind::Allocation, "Responsibility", owner, work);
+        Fixture {
+            project,
+            diagram,
+            performer,
+            work,
+            node,
+        }
+    }
+
+    fn semantic(f: &Fixture) -> (plan::Scope, plan::SemanticPlan) {
+        let scope = plan::capture(&f.project, f.diagram, f.work, f.node).unwrap();
+        let semantic = plan::plan_semantics(
+            &f.project,
+            &scope,
+            plan::Destination::OutsidePerformers,
+            &BTreeMap::new(),
+        )
+        .unwrap();
+        (scope, semantic)
+    }
+
+    fn presentation() -> plan::PresentationContext {
+        plan::PresentationContext {
+            viewport: plan::Rect {
+                position: xy(-2000., -2000.),
+                size: Size {
+                    width: 5000.,
+                    height: 5000.,
+                },
+            },
+            zoom: 1.,
+            target: None,
+        }
+    }
+
+    #[test]
+    fn each_outgoing_edge_clears_the_source_and_passes_ordinary_placement() {
+        for layer in [Layer::Oa, Layer::Sa] {
+            let f = fixture(layer);
+            let (scope, semantic) = semantic(&f);
+            for (start, pointer, requested, expected) in [
+                (
+                    Point::new(170., 210.),
+                    Point::new(99., 210.),
+                    xy(89., 180.),
+                    xy(-140., 180.),
+                ),
+                (
+                    Point::new(340., 210.),
+                    Point::new(501., 210.),
+                    xy(321., 180.),
+                    xy(510., 180.),
+                ),
+                (
+                    Point::new(200., 190.),
+                    Point::new(200., 99.),
+                    xy(160., 89.),
+                    xy(160., -10.),
+                ),
+                (
+                    Point::new(200., 260.),
+                    Point::new(200., 351.),
+                    xy(160., 271.),
+                    xy(160., 360.),
+                ),
+            ] {
+                assert!(matches!(
+                    plan::place(&semantic, requested, presentation()),
+                    Err(plan::Refusal::LayoutRequired(_))
+                ));
+                let proposed = requests(
+                    (&f.project, &ViewIndex::new(&f.project)),
+                    (semantic.project(), semantic.index()),
+                    f.diagram,
+                    &scope.placements,
+                    f.node,
+                    requested,
+                    (start, pointer),
+                );
+                assert_eq!(proposed, vec![expected]);
+                let placed = plan::place(&semantic, proposed[0], presentation()).unwrap();
+                assert!(
+                    plan::finish(&semantic, &f.project, &placed)
+                        .unwrap()
+                        .is_some()
+                );
+            }
+        }
+    }
+
+    #[test]
+    fn source_shrink_uses_candidate_enclosure_not_frozen_target() {
+        let mut f = fixture(Layer::Oa);
+        f.project
+            .diagrams
+            .get_mut(&f.diagram)
+            .unwrap()
+            .nodes
+            .get_mut(&f.performer)
+            .unwrap()
+            .size = Size {
+            width: 224.,
+            height: 94.,
+        };
+        let (scope, semantic) = semantic(&f);
+        let proposed = requests(
+            (&f.project, &ViewIndex::new(&f.project)),
+            (semantic.project(), semantic.index()),
+            f.diagram,
+            &scope.placements,
+            f.node,
+            xy(229., 180.),
+            (Point::new(340., 210.), Point::new(409., 210.)),
+        );
+        assert_eq!(proposed, vec![xy(340., 180.)]);
+        plan::place(&semantic, proposed[0], presentation()).unwrap();
+    }
+
+    #[test]
+    fn corner_order_follows_boundary_crossing_and_is_deterministic() {
+        let f = fixture(Layer::Sa);
+        let (scope, semantic) = semantic(&f);
+        // Right crossed at 160/161 of the segment; bottom at 90/91.
+        let args = (
+            xy(321., 271.),
+            Point::new(340., 260.),
+            Point::new(501., 351.),
+        );
+        let proposed = requests(
+            (&f.project, &ViewIndex::new(&f.project)),
+            (semantic.project(), semantic.index()),
+            f.diagram,
+            &scope.placements,
+            f.node,
+            args.0,
+            (args.1, args.2),
+        );
+        assert_eq!(proposed, vec![xy(320., 360.), xy(510., 270.)]);
+        assert_eq!(
+            proposed,
+            requests(
+                (&f.project, &ViewIndex::new(&f.project)),
+                (semantic.project(), semantic.index()),
+                f.diagram,
+                &scope.placements,
+                f.node,
+                args.0,
+                (args.1, args.2)
+            )
+        );
+    }
+
+    #[test]
+    fn no_crossing_no_overlap_no_source_and_nonfinite_requests_are_empty() {
+        let f = fixture(Layer::Oa);
+        let (scope, semantic) = semantic(&f);
+        for (requested, pointer) in [
+            (xy(170., 180.), Point::new(210., 210.)),
+            (xy(700., 180.), Point::new(740., 210.)),
+            (xy(f32::NAN, 180.), Point::new(99., 210.)),
+            (xy(89., 180.), Point::new(f32::INFINITY, 210.)),
+        ] {
+            assert!(
+                requests(
+                    (&f.project, &ViewIndex::new(&f.project)),
+                    (semantic.project(), semantic.index()),
+                    f.diagram,
+                    &scope.placements,
+                    f.node,
+                    requested,
+                    (Point::new(200., 210.), pointer)
+                )
+                .is_empty()
+            );
+        }
+        assert!(
+            requests(
+                (semantic.project(), semantic.index()),
+                (semantic.project(), semantic.index()),
+                f.diagram,
+                &scope.placements,
+                f.node,
+                xy(89., 180.),
+                (Point::new(200., 210.), Point::new(99., 210.))
+            )
+            .is_empty()
+        );
+    }
+
+    #[test]
+    fn descendant_footprint_controls_clearance_without_mutating_projects() {
+        for layer in [Layer::Oa, Layer::Sa] {
+            let mut f = fixture(layer);
+            let kind = f.project.elements[&f.work].kind();
+            let child = f
+                .project
+                .add_element(kind, layer, "Child", Some(f.work))
+                .unwrap();
+            let child_node = f.project.place(f.diagram, child, xy(240., 270.));
+            // First-child allocation transfer is normally performed by commands;
+            // this fixture expresses the resulting leaf allocation directly.
+            f.project.relations.clear();
+            let owner = f.project.diagrams[&f.diagram].nodes[&f.performer].element;
+            f.project.relate(
+                RelationKind::Allocation,
+                "Leaf responsibility",
+                owner,
+                child,
+            );
+            let (scope, semantic) = semantic(&f);
+            assert!(scope.placements.contains_key(&child_node));
+            let before = f.project.clone();
+            let candidate = semantic.project().clone();
+            let proposed = requests(
+                (&f.project, &ViewIndex::new(&f.project)),
+                (&candidate, semantic.index()),
+                f.diagram,
+                &scope.placements,
+                f.node,
+                xy(89., 180.),
+                (Point::new(170., 210.), Point::new(99., 210.)),
+            );
+            assert_eq!(proposed, vec![xy(-240., 180.)]);
+            let placed = plan::place(&semantic, proposed[0], presentation()).unwrap();
+            let root = &placed.diagram.nodes[&f.node];
+            let child = &placed.diagram.nodes[&child_node];
+            assert_eq!(child.position.x - root.position.x, 80.);
+            assert_eq!(child.position.y - root.position.y, 90.);
+            assert_eq!(f.project, before);
+            assert_eq!(semantic.project(), &candidate);
+        }
+    }
+
+    #[test]
+    fn independent_selected_roots_keep_one_rigid_group_translation() {
+        for layer in [Layer::Oa, Layer::Sa] {
+            let mut f = fixture(layer);
+            let kind = f.project.elements[&f.work].kind();
+            let second = f
+                .project
+                .add_element(kind, layer, "Second work", None)
+                .unwrap();
+            let second_node = f.project.place(f.diagram, second, xy(240., 300.));
+            let owner = f.project.diagrams[&f.diagram].nodes[&f.performer].element;
+            f.project.relate(
+                RelationKind::Allocation,
+                "Second responsibility",
+                owner,
+                second,
+            );
+            let selected = BTreeMap::from([(f.node, f.work), (second_node, second)]);
+            let scope =
+                plan::assignment::capture(&f.project, f.diagram, &selected, f.node).unwrap();
+            let semantic = plan::assignment::plan_semantics(
+                &scope,
+                plan::Destination::OutsidePerformers,
+                &BTreeMap::new(),
+            )
+            .unwrap();
+            let proposed = requests(
+                (&f.project, &ViewIndex::new(&f.project)),
+                (semantic.project(), semantic.index()),
+                f.diagram,
+                scope.affected(),
+                f.node,
+                xy(89., 180.),
+                (Point::new(170., 210.), Point::new(99., 210.)),
+            );
+            assert_eq!(proposed, vec![xy(-220., 180.)]);
+            let placed = plan::assignment::place(&semantic, proposed[0], presentation()).unwrap();
+            let root = &placed.diagram.nodes[&f.node];
+            let second = &placed.diagram.nodes[&second_node];
+            assert_eq!(second.position.x - root.position.x, 80.);
+            assert_eq!(second.position.y - root.position.y, 120.);
+            assert!(
+                plan::assignment::finish(&semantic, &f.project, &placed)
+                    .unwrap()
+                    .is_some()
+            );
+        }
+    }
+}

crates/oa-desktop/src/app/allocation_drag_full_tree_tests.rs

@@ -30,6 +30,117 @@ async fn mount() -> (Fixture, Mounted) {
     mounted.settle(&mut f.app).await;
     (f, mounted)
 }
+
+#[tokio::test]
+async fn actual_tree_outgoing_boundary_motion_preview_release_and_cancel() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut f = outgoing_fixture(layer);
+        f.app.layer = layer;
+        f.app.window_size = iced::Size::new(1440., 900.);
+        let _ = f.app.update(Message::Select(f.work));
+        let mut mounted = Mounted::new(&mut f.app).await;
+        f.app.zoom = 0.75;
+        f.app.pan = Vector::new(20., 15.);
+        f.app.fit_to_view = false;
+        mounted.settle(&mut f.app).await;
+        let original = f.app.project().clone();
+        let source = f.app.document.bundle().clone();
+        let from = at(&mut mounted, &f, xy(660., 225.));
+        mounted
+            .batch(
+                &mut f.app,
+                &[
+                    Input::Mouse(mouse::Event::CursorMoved { position: from }),
+                    Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                ],
+                mouse::Cursor::Available(from),
+            )
+            .await;
+        // Separate input/update/layout turns expose the held boundary transition
+        // that a one-batch distant drop cannot exercise.
+        for x in [620., 560., 510., 499., 490.] {
+            let to = at(&mut mounted, &f, xy(x, 225.));
+            mounted
+                .batch(
+                    &mut f.app,
+                    &[Input::Mouse(mouse::Event::CursorMoved { position: to })],
+                    mouse::Cursor::Available(to),
+                )
+                .await;
+            assert_eq!(f.app.project(), &original);
+            assert_eq!(f.app.document.bundle(), &source);
+            assert!(
+                !f.app.allocation_drag.feedback.as_ref().unwrap().refused,
+                "{layer:?} x={x}: {}",
+                f.app.status
+            );
+            assert!(f.app.allocation_drag.preview.is_some());
+            let _ = mounted.pixels(&f.app);
+        }
+        let expected = f
+            .app
+            .allocation_drag
+            .preview
+            .as_ref()
+            .unwrap()
+            .placement
+            .diagram
+            .clone();
+        let to = at(&mut mounted, &f, xy(490., 225.));
+        mounted
+            .batch(
+                &mut f.app,
+                &[Input::Mouse(mouse::Event::ButtonReleased(
+                    mouse::Button::Left,
+                ))],
+                mouse::Cursor::Available(to),
+            )
+            .await;
+        assert_eq!(&f.app.project().diagrams[&f.diagram], &expected);
+        assert!(
+            !f.app
+                .project()
+                .relations
+                .values()
+                .any(|r| r.kind() == RelationKind::Allocation && r.target() == f.work)
+        );
+        let _ = f.app.update(Message::Undo);
+        mounted.settle(&mut f.app).await;
+        assert_eq!(f.app.document.bundle(), &source);
+        let from = at(&mut mounted, &f, xy(660., 225.));
+        let to = at(&mut mounted, &f, xy(490., 225.));
+        mounted
+            .batch(
+                &mut f.app,
+                &[
+                    Input::Mouse(mouse::Event::CursorMoved { position: from }),
+                    Input::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)),
+                    Input::Mouse(mouse::Event::CursorMoved { position: to }),
+                ],
+                mouse::Cursor::Available(to),
+            )
+            .await;
+        mounted
+            .batch(
+                &mut f.app,
+                &[key(keyboard::key::Named::Escape)],
+                mouse::Cursor::Available(to),
+            )
+            .await;
+        mounted
+            .batch(
+                &mut f.app,
+                &[Input::Mouse(mouse::Event::ButtonReleased(
+                    mouse::Button::Left,
+                ))],
+                mouse::Cursor::Available(to),
+            )
+            .await;
+        assert_eq!(f.app.document.bundle(), &source);
+        assert!(f.app.allocation_drag.preview.is_none());
+        assert!(!f.app.document.can_undo());
+    }
+}
 fn canvas_bounds(mounted: &mut Mounted, app: &App) -> Rectangle {
     mounted
         .geometry(app)
@@ -481,6 +592,7 @@ async fn actual_app_tree_exact_incoming_drag_keeps_destination_visible_and_canva
             if pan.y == -100. {
                 // A genuine clipping refusal in the same held gesture, then
                 // recovery at the original exact point: no camera rebasing.
+                let retained = f.app.allocation_drag.preview.clone().unwrap();
                 let clipped = at(&mut mounted, &f, xy(160., 110.));
                 mounted
                     .batch(
@@ -492,7 +604,19 @@ async fn actual_app_tree_exact_incoming_drag_keeps_destination_visible_and_canva
                     )
                     .await;
                 assert!(f.app.allocation_drag.feedback.as_ref().unwrap().refused);
-                assert!(f.app.allocation_drag.preview.is_none());
+                assert!(Arc::ptr_eq(
+                    f.app.allocation_drag.preview.as_ref().unwrap(),
+                    &retained
+                ));
+                assert!(
+                    f.app
+                        .allocation_drag
+                        .feedback
+                        .as_ref()
+                        .unwrap()
+                        .ghost_delta
+                        .is_some()
+                );
                 assert_eq!(canvas_bounds(&mut mounted, &f.app), canvas);
                 assert_eq!(destination_bounds(&mut mounted, &f.app), slot);
                 assert_eq!(f.app.project(), &before);

crates/oa-desktop/src/app/allocation_drag_tests.rs

@@ -1239,6 +1239,7 @@ fn destination_identity_does_not_describe_blocked_or_outside_viewport_as_unalloc
         inspection_targets: vec![],
         text: "A card blocks this drop".into(),
         refused: true,
+        ghost_delta: None,
     };
     assert_eq!(feedback.destination_identity(), "No eligible destination");
     feedback.text = "Release inside the captured canvas".into();
@@ -1246,3 +1247,361 @@ fn destination_identity_does_not_describe_blocked_or_outside_viewport_as_unalloc
     feedback.refused = false;
     assert_eq!(feedback.destination_identity(), "Outside performers");
 }
+
+fn outgoing_fixture(layer: Layer) -> Fixture {
+    let mut f = fixture(layer);
+    drag(&mut f, screen(xy(160., 190.)));
+    let mut project = f.app.project().clone();
+    let d = project.diagrams.get_mut(&f.diagram).unwrap();
+    let performer = d.nodes.values_mut().find(|n| n.element == f.a).unwrap();
+    performer.position = xy(500., 100.);
+    performer.size = Size {
+        width: 300.,
+        height: 300.,
+    };
+    d.nodes.get_mut(&f.node).unwrap().position = xy(540., 190.);
+    replace(&mut f, project);
+    f
+}
+
+#[test]
+fn outgoing_boundary_drop_clears_source_without_changing_other_placements() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut f = outgoing_fixture(layer);
+        let before = f.app.project().clone();
+        let source = f.app.document.bundle().clone();
+        let from = screen(xy(660., 225.));
+        let to = screen(xy(490., 225.));
+        let mut events = batch(&f.app, from, to);
+        let release = events.pop().unwrap();
+        send(&mut f.app, events);
+        let feedback = f.app.allocation_drag.feedback.as_ref().unwrap();
+        assert!(!feedback.refused, "{}", feedback.text);
+        let preview = f.app.allocation_drag.preview.as_ref().unwrap();
+        let expected_diagram = preview.placement.diagram.clone();
+        let work = &expected_diagram.nodes[&f.node];
+        assert!(work.position.x + work.size.width <= 490.);
+        assert_eq!(work.position.y, 190.);
+        for (id, node) in &before.diagrams[&f.diagram].nodes {
+            if *id != f.node {
+                assert_eq!(&expected_diagram.nodes[id], node);
+            }
+        }
+        assert_eq!(f.app.project(), &before);
+        assert_eq!(f.app.document.bundle(), &source);
+        let _ = f.app.update(release);
+        assert_eq!(&f.app.project().diagrams[&f.diagram], &expected_diagram);
+        assert!(
+            !f.app
+                .project()
+                .relations
+                .values()
+                .any(|r| r.kind() == RelationKind::Allocation && r.target() == f.work)
+        );
+        let after = f.app.project().clone();
+        let saved = f.app.document.bundle().clone();
+        let _ = f.app.update(Message::Undo);
+        assert_eq!(f.app.project(), &before);
+        assert_eq!(f.app.document.bundle(), &source);
+        assert!(!f.app.document.can_undo());
+        let _ = f.app.update(Message::Redo);
+        assert_eq!(f.app.project(), &after);
+        assert_eq!(f.app.document.bundle(), &saved);
+    }
+}
+
+#[test]
+fn outgoing_clearance_collision_refuses_release_without_source_or_history_mutation() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut f = outgoing_fixture(layer);
+        let mut project = f.app.project().clone();
+        let obstacle = project
+            .add_element(
+                project.elements[&f.work].kind(),
+                layer,
+                "Unrelated work",
+                None,
+            )
+            .unwrap();
+        let obstacle_node = project.place(f.diagram, obstacle, xy(240., 190.));
+        replace(&mut f, project);
+        // A refused release must preserve an existing redo branch, too.
+        let _ = f.app.update(Message::Command(Command::Rename(
+            f.work,
+            "Temporary".into(),
+        )));
+        let _ = f.app.update(Message::Undo);
+        let before = f.app.project().clone();
+        let source = f.app.document.bundle().clone();
+        let snapshot = f.app.document.snapshot();
+        let revision = f.app.document.revision();
+        let from = screen(xy(660., 225.));
+        let to = screen(xy(490., 225.));
+        let mut events = batch(&f.app, from, to);
+        let release = events.pop().unwrap();
+        send(&mut f.app, events);
+
+        let active = f.app.allocation_drag.active.as_ref().unwrap();
+        let p = &active.press;
+        let frozen = active.frozen.as_ref().unwrap();
+        let owner = frozen.targets.iter().find(|t| t.element == f.a).unwrap();
+        assert_eq!(p.start, from);
+        assert!(contains(owner.region, p.stamp.world(from)));
+        assert!(p.stamp.world(to).x < owner.region.x);
+        assert_eq!(
+            frozen.resolve(p.stamp, Some(to), false),
+            Hit::Destination(plan::Destination::OutsidePerformers, None),
+            "The pointer must reach empty canvas, not be occluded by the obstacle"
+        );
+        let candidate = active
+            .cache
+            .iter()
+            .find(|(destination, _)| *destination == plan::Destination::OutsidePerformers)
+            .unwrap()
+            .1
+            .as_ref()
+            .unwrap();
+        let affected = match &active.prepared {
+            Prepared::Singleton(scope) => &scope.placements,
+            Prepared::Assignment(scope) => scope.affected(),
+            _ => panic!("expected assignment gesture"),
+        };
+        let requested = xy(370., 190.);
+        let presentation = plan::PresentationContext {
+            viewport: p.stamp.viewport(),
+            zoom: p.stamp.zoom,
+            target: None,
+        };
+        assert!(matches!(
+            candidate.place(requested, presentation),
+            Err(plan::Refusal::LayoutRequired(_))
+        ));
+        let proposed = clearance::requests(
+            (f.app.project(), f.app.document.view_index()),
+            (candidate.project(), candidate.index()),
+            f.diagram,
+            affected,
+            f.node,
+            requested,
+            (p.stamp.world(from), p.stamp.world(to)),
+        );
+        assert_eq!(
+            proposed.len(),
+            1,
+            "a genuine left crossing must propose clearance"
+        );
+        assert!(proposed[0].x < requested.x);
+        let work = &before.diagrams[&f.diagram].nodes[&f.node];
+        let obstacle = &before.diagrams[&f.diagram].nodes[&obstacle_node];
+        assert!(obstacle.position.x + obstacle.size.width < 490.);
+        assert!(proposed[0].x + work.size.width <= owner.region.x - 10.);
+        assert!(proposed[0].x < obstacle.position.x + obstacle.size.width);
+        assert!(obstacle.position.x < proposed[0].x + work.size.width);
+        assert_eq!(proposed[0].y, obstacle.position.y);
+        assert!(matches!(
+            candidate.place(proposed[0], presentation),
+            Err(plan::Refusal::LayoutRequired(message)) if message.contains("overlapping cards")
+        ));
+        let feedback = f.app.allocation_drag.feedback.as_ref().unwrap();
+        assert!(feedback.refused, "{}", feedback.text);
+        assert!(feedback.ghost_delta.is_some());
+        assert!(f.app.allocation_drag.preview.is_none());
+        assert_eq!(f.app.project(), &before);
+        assert_eq!(f.app.document.bundle(), &source);
+        assert!(Arc::ptr_eq(&snapshot, &f.app.document.snapshot()));
+        let _ = f.app.update(release);
+        assert!(
+            f.app.status.contains("overlapping cards"),
+            "{}",
+            f.app.status
+        );
+        assert!(f.app.allocation_drag.active.is_none());
+        assert!(f.app.allocation_drag.preview.is_none());
+        assert_eq!(f.app.project(), &before);
+        assert_eq!(f.app.document.bundle(), &source);
+        assert_eq!(f.app.document.revision(), revision);
+        assert!(Arc::ptr_eq(&snapshot, &f.app.document.snapshot()));
+        assert!(!f.app.document.can_undo());
+        assert!(f.app.document.can_redo());
+    }
+}
+
+#[test]
+fn outgoing_clearance_preserves_source_enclosure_and_allocated_sibling() {
+    for layer in [Layer::Oa, Layer::Sa] {
+        let mut f = outgoing_fixture(layer);
+        let mut project = f.app.project().clone();
+        let sibling = project
+            .add_element(
+                project.elements[&f.work].kind(),
+                layer,
+                "Remaining work",
+                None,
+            )
+            .unwrap();
+        let sibling_node = project.place(f.diagram, sibling, xy(540., 450.));
+        let allocation = project.relate(
+            RelationKind::Allocation,
+            "Keep responsibility",
+            f.a,
+            sibling,
+        );
+        replace(&mut f, project);
+        let before = f.app.project().clone();
+        let source = f.app.document.bundle().clone();
+        let view = projection::project_view(&before, f.diagram);
+        let owner = view.nodes.iter().find(|n| n.element == f.a).unwrap();
+        let bottom = owner.position.y + owner.size.height;
+        let stored_owner = &before.diagrams[&f.diagram].nodes[&owner.id];
+        assert!(
+            bottom > stored_owner.position.y + stored_owner.size.height,
+            "The retained sibling must enlarge the projected source enclosure"
+        );
+        let from = screen(xy(660., 225.));
+        let to = screen(xy(660., bottom + 1.));
+        let mut events = batch(&f.app, from, to);
+        let release = events.pop().unwrap();
+        send(&mut f.app, events);
+        let active = f.app.allocation_drag.active.as_ref().unwrap();
+        let p = &active.press;
+        let frozen = active.frozen.as_ref().unwrap();
+        let target = frozen.targets.iter().find(|t| t.element == f.a).unwrap();
+        assert_eq!(p.start, from);
+        assert!(contains(target.region, p.stamp.world(from)));
+        assert!(p.stamp.world(to).y >= target.region.y + target.region.height);
+        assert_eq!(
+            frozen.resolve(p.stamp, Some(to), false),
+            Hit::Destination(plan::Destination::OutsidePerformers, None)
+        );
+        let preview = f.app.allocation_drag.preview.as_ref().expect(&f.app.status);
+        assert!(!f.app.allocation_drag.feedback.as_ref().unwrap().refused);
+        let requested = xy(540., 190. + to.y - from.y);
+        assert!(matches!(
+            preview.candidate.place(
+                requested,
+                plan::PresentationContext {
+                    viewport: p.stamp.viewport(),
+                    zoom: p.stamp.zoom,
+                    target: None,
+                }
+            ),
+            Err(plan::Refusal::LayoutRequired(_))
+        ));
+        let moved = &preview.placement.diagram.nodes[&f.node];
+        assert_eq!(moved.position.x, 540.);
+        assert!(moved.position.y >= bottom + 10.);
+        assert!(moved.position.y > requested.y);
+        assert_eq!(
+            preview
+                .placement
+                .view
+                .nodes
+                .iter()
+                .find(|n| n.id == owner.id)
+                .unwrap(),
+            owner
+        );
+        let remaining = preview
+            .placement
+            .view
+            .nodes
+            .iter()
+            .find(|n| n.id == sibling_node)
+            .unwrap();
+        assert_eq!(remaining.visual_parent, Some(owner.id));
+        assert_eq!(
+            remaining.position,
+            before.diagrams[&f.diagram].nodes[&sibling_node].position
+        );
+        assert_eq!(
+            &preview.project().relations[&allocation],
+            &before.relations[&allocation]
+        );
+        for (id, node) in &before.diagrams[&f.diagram].nodes {
+            if *id != f.node {
+                assert_eq!(&preview.placement.diagram.nodes[id], node);
+            }
+        }
+        let mut expected = preview.project().clone();
+        expected
+            .diagrams
+            .insert(f.diagram, preview.placement.diagram.clone());
+        assert_eq!(f.app.project(), &before);
+        assert_eq!(f.app.document.bundle(), &source);
+        let _ = f.app.update(release);
+        assert_eq!(f.app.project(), &expected, "{}", f.app.status);
+        assert_eq!(f.app.document.revision(), 1);
+        assert_eq!(
+            validation::effective_performer(f.app.project(), f.work),
+            None
+        );
+        assert_eq!(
+            validation::effective_performer(f.app.project(), sibling),
+            Some(f.a)
+        );
+        assert_eq!(
+            &f.app.project().relations[&allocation],
+            &before.relations[&allocation]
+        );
+        let after = f.app.document.bundle().clone();
+        let _ = f.app.update(Message::Undo);
+        assert_eq!(f.app.project(), &before);
+        assert_eq!(f.app.document.bundle(), &source);
+        assert!(!f.app.document.can_undo());
+        let _ = f.app.update(Message::Redo);
+        assert_eq!(f.app.project(), &expected);
+        assert_eq!(f.app.document.bundle(), &after);
+    }
+}
+
+#[test]
+fn refused_motion_retains_last_scene_but_release_never_commits_it() {
+    let mut f = outgoing_fixture(Layer::Sa);
+    let mut project = f.app.project().clone();
+    let obstacle = project
+        .add_element(Kind::Function, Layer::Sa, "Unrelated work", None)
+        .unwrap();
+    project.place(f.diagram, obstacle, xy(1250., 120.));
+    replace(&mut f, project);
+    let original = f.app.project().clone();
+    let source = f.app.document.bundle().clone();
+    let p = admit_press(&mut f);
+    let clear = screen(xy(450., 225.));
+    let _ = f.app.update(Message::WorkDrag(Event::Preview(
+        p.stamp,
+        p.token,
+        Some(clear),
+    )));
+    let last = f.app.allocation_drag.preview.clone().expect(&f.app.status);
+    // Another work card blocks this location: the prior legal outgoing scene is display
+    // state only, and must not become a fallback command on release.
+    let blocked = screen(xy(1260., 130.));
+    let _ = f.app.update(Message::WorkDrag(Event::Preview(
+        p.stamp,
+        p.token,
+        Some(blocked),
+    )));
+    assert!(f.app.allocation_drag.feedback.as_ref().unwrap().refused);
+    assert!(
+        f.app
+            .allocation_drag
+            .feedback
+            .as_ref()
+            .unwrap()
+            .ghost_delta
+            .is_some()
+    );
+    assert!(Arc::ptr_eq(
+        f.app.allocation_drag.preview.as_ref().unwrap(),
+        &last
+    ));
+    let _ = f.app.update(Message::WorkDrag(Event::Release(
+        p.stamp,
+        p.token,
+        Some(blocked),
+    )));
+    assert_eq!(f.app.project(), &original);
+    assert_eq!(f.app.document.bundle(), &source);
+    assert!(!f.app.document.can_undo());
+    assert!(f.app.allocation_drag.preview.is_none());
+}

crates/oa-desktop/src/app/state_picker_escape_tests.rs

@@ -10,6 +10,11 @@ async fn press_escape(mounted: &mut Mounted, app: &mut App) -> Vec<Message> {
         std::slice::from_ref(&input),
         mouse::Cursor::Unavailable,
     );
+    assert_eq!(
+        statuses,
+        [iced::event::Status::Captured],
+        "the mounted picker must capture Escape before App subscriptions"
+    );
     crate::app::escape::tests::subscriptions(app, input, statuses[0], &mut messages);
     for message in messages.iter().cloned() {
         let task = app.update(message);
@@ -41,17 +46,11 @@ async fn mounted_state_missing_picker_escape_preserves_exact_document_then_reope
     send(&mut app, Message::BehaviorDiagram(choice));
     let mut mounted = Mounted::new(&mut app).await;
     assert_eq!(state_edit::unplaced(app.project(), diagram), vec![f.b]);
-    let focus_id = iced::advanced::widget::Id::from("diagram-keyboard-owner");
-    let (_, canvas, _) = mounted
-        .geometry(&app)
-        .focused
-        .into_iter()
-        .find(|(id, _, _)| id.as_ref() == Some(&focus_id))
-        .unwrap();
-    // The existing picker is immediately above the measured canvas, separated
-    // by 8px. Its 12px text and 8px padding give a 31.6px row.
-    let picker = iced::Point::new(canvas.center_x(), canvas.y - 24.);
-    let option = iced::Point::new(picker.x, canvas.y + 8.);
+    // Locate the stable picker slot itself: selection controls may sit between
+    // it and the canvas. The single menu option opens below this slot.
+    let bounds = mounted.geometry(&app).bounds("state-missing-picker");
+    let picker = bounds.center();
+    let option = iced::Point::new(picker.x, bounds.y + bounds.height * 1.5);
     let before = app.document.snapshot();
     let original = app.project().clone();
     let source = app.document.bundle().clone();

crates/oa-desktop/src/behavior/state_view.rs

@@ -187,7 +187,7 @@ pub fn view<'a>(app: &'a App, machine: Id, mut out: Column<'a, Message>) -> Elem
     .into();
     out = out.push(
         column![
-            missing_controls,
+            container(missing_controls).id("state-missing-picker"),
             selection_controls(app),
             crate::diagram::focus::wrap(
                 canvas.map(event),

crates/oa-desktop/src/diagram.rs

@@ -42,6 +42,7 @@ mod port_labels;
 pub use port_labels::PortLabels;
 #[path = "diagram/focus.rs"]
 pub(crate) mod focus;
+mod grid;
 pub(crate) mod group_gesture;
 mod multiselect;
 #[cfg(test)]
@@ -71,6 +72,7 @@ pub struct DiagramCanvas<'a> {
 }
 #[derive(Default)]
 pub struct State {
+    grid: grid::Grid,
     modifiers: iced::keyboard::Modifiers,
     group: Option<multiselect::Press>,
     work: Option<Arc<crate::app::allocation_drag::Press>>,
@@ -1251,23 +1253,10 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
         bounds: Rectangle,
         _: mouse::Cursor,
     ) -> Vec<canvas::Geometry> {
+        let background = state
+            .grid
+            .draw(renderer, bounds.size(), self.zoom, self.pan);
         let mut f = Frame::new(renderer, bounds.size());
-        f.fill_rectangle(
-            Point::ORIGIN,
-            bounds.size(),
-            Color::from_rgb8(246, 248, 251),
-        );
-        let step = (24. * self.zoom).max(14.);
-        let ox = self.pan.x.rem_euclid(step);
-        let oy = self.pan.y.rem_euclid(step);
-        for x in 0..(bounds.width / step) as i32 + 1 {
-            for y in 0..(bounds.height / step) as i32 + 1 {
-                f.fill(
-                    &Path::circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65),
-                    style::LINE,
-                );
-            }
-        }
         f.translate(self.pan);
         f.scale(self.zoom);
         let scene = self.scene(state);
@@ -1670,7 +1659,7 @@ impl canvas::Program<Message> for DiagramCanvas<'_> {
                 ..Default::default()
             });
         }
-        vec![f.into_geometry(), overlay.into_geometry()]
+        vec![background, f.into_geometry(), overlay.into_geometry()]
     }
     fn mouse_interaction(
         &self,

crates/oa-desktop/src/diagram/grid.rs

@@ -0,0 +1,50 @@
+//! Screen-space background geometry, independent of the model and pointer.
+use super::*;
+use std::cell::Cell;
+
+#[derive(Default)]
+pub(super) struct Grid {
+    geometry: canvas::Cache,
+    camera: Cell<Option<(f32, Vector)>>,
+    #[cfg(test)]
+    builds: Cell<usize>,
+}
+
+impl Grid {
+    pub(super) fn draw(
+        &self,
+        renderer: &Renderer,
+        size: Size,
+        zoom: f32,
+        pan: Vector,
+    ) -> canvas::Geometry {
+        // Cache::draw handles exact size changes. Raw camera equality is
+        // deliberately conservative: do not quantize fractional antialiasing.
+        if self.camera.replace(Some((zoom, pan))) != Some((zoom, pan)) {
+            self.geometry.clear();
+        }
+        self.geometry.draw(renderer, size, |frame| {
+            #[cfg(test)]
+            self.builds.set(self.builds.get() + 1);
+            paint(frame, size, zoom, pan);
+        })
+    }
+}
+
+fn paint(frame: &mut Frame, size: Size, zoom: f32, pan: Vector) {
+    frame.fill_rectangle(Point::ORIGIN, size, Color::from_rgb8(246, 248, 251));
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            frame.fill(
+                &Path::circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65),
+                style::LINE,
+            );
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests;

crates/oa-desktop/src/diagram/grid/tests.rs

@@ -0,0 +1,378 @@
+use super::*;
+use iced::advanced::{
+    graphics::geometry::Renderer as _,
+    renderer::{Headless, Renderer as _},
+};
+
+async fn renderer() -> Renderer {
+    <Renderer as Headless>::new(iced::Font::DEFAULT, 16.into(), None)
+        .await
+        .expect("grid tests require the supported WGPU headless renderer")
+}
+
+#[tokio::test]
+async fn cache_reuses_unchanged_inputs_and_rebuilds_for_each_camera_or_size_change() {
+    let renderer = renderer().await;
+    let grid = Grid::default();
+    let original = Size::new(320., 240.);
+    let threshold = 14. / 24.;
+    // Each row changes exactly one dependency from its predecessor. Returning
+    // to old dimensions must invalidate too; this cache holds one viewport.
+    let cases = [
+        ("initial", original, 1., Vector::ZERO),
+        ("positive x pan", original, 1., Vector::new(24., 0.)),
+        ("negative x pan", original, 1., Vector::new(-24., 0.)),
+        ("fractional x pan", original, 1., Vector::new(-24.25, 0.)),
+        ("positive y pan", original, 1., Vector::new(-24.25, 18.)),
+        ("negative y pan", original, 1., Vector::new(-24.25, -18.)),
+        ("fractional y pan", original, 1., Vector::new(-24.25, -18.5)),
+        ("return to zero pan", original, 1., Vector::ZERO),
+        ("zoom at zero pan", original, 1.25, Vector::ZERO),
+        (
+            "below spacing threshold",
+            original,
+            threshold - 0.001,
+            Vector::ZERO,
+        ),
+        ("at spacing threshold", original, threshold, Vector::ZERO),
+        (
+            "above spacing threshold",
+            original,
+            threshold + 0.001,
+            Vector::ZERO,
+        ),
+        (
+            "width only",
+            Size::new(321., 240.),
+            threshold + 0.001,
+            Vector::ZERO,
+        ),
+        ("return width", original, threshold + 0.001, Vector::ZERO),
+        (
+            "height only",
+            Size::new(320., 241.),
+            threshold + 0.001,
+            Vector::ZERO,
+        ),
+        ("return height", original, threshold + 0.001, Vector::ZERO),
+        (
+            "fractional width",
+            Size::new(320.25, 240.),
+            threshold + 0.001,
+            Vector::ZERO,
+        ),
+        (
+            "fractional height",
+            Size::new(320.25, 240.5),
+            threshold + 0.001,
+            Vector::ZERO,
+        ),
+    ];
+    for (index, (label, size, zoom, pan)) in cases.into_iter().enumerate() {
+        let _ = grid.draw(&renderer, size, zoom, pan);
+        assert_eq!(grid.builds.get(), index + 1, "{label} must rebuild");
+        for _ in 0..3 {
+            let _ = grid.draw(&renderer, size, zoom, pan);
+            assert_eq!(grid.builds.get(), index + 1, "{label} must reuse");
+        }
+    }
+}
+
+// Independent reference copied from the former DiagramCanvas::draw background
+// pass. Do not call grid::paint here: a shared implementation would hide changes
+// in spacing, phase, radius, color, or coverage from the parity comparison.
+fn legacy_background(frame: &mut Frame, size: Size, zoom: f32, pan: Vector) {
+    frame.fill_rectangle(Point::ORIGIN, size, Color::from_rgb8(246, 248, 251));
+    let spacing = (24. * zoom).max(14.);
+    let offset_x = pan.x.rem_euclid(spacing);
+    let offset_y = pan.y.rem_euclid(spacing);
+    for column in 0..(size.width / spacing) as i32 + 1 {
+        for row in 0..(size.height / spacing) as i32 + 1 {
+            frame.fill(
+                &Path::circle(
+                    Point::new(
+                        offset_x + column as f32 * spacing,
+                        offset_y + row as f32 * spacing,
+                    ),
+                    0.65,
+                ),
+                Color::from_rgb(0.86, 0.89, 0.91),
+            );
+        }
+    }
+}
+
+fn foreground(frame: &mut Frame, zoom: f32, pan: Vector, changed: bool) {
+    frame.translate(pan);
+    frame.scale(zoom);
+    // Crossing paths pass behind opaque cards. The long paths also cross the
+    // screen-space warning, making geometry order observable.
+    for (start, end, color) in [
+        (Point::new(0., 20.), Point::new(300., 210.), style::TEAL),
+        (Point::new(0., 210.), Point::new(300., 20.), style::BOUNDARY),
+    ] {
+        frame.stroke(
+            &Path::line(start, end),
+            Stroke::default().with_color(color).with_width(3.),
+        );
+    }
+    let shift = if changed { 19.5 } else { 0. };
+    frame.fill_rectangle(
+        Point::new(12., 92.),
+        Size::new(270., 35.),
+        Color::from_rgba(0.1, 0.6, 0.5, 0.25),
+    );
+    for (position, size, title) in [
+        (Point::new(32. + shift, 58.), Size::new(116., 72.), "Sensor"),
+        (Point::new(172., 139.), Size::new(118., 66.), "Controller"),
+    ] {
+        frame.fill_rectangle(position, size, Color::WHITE);
+        frame.stroke(
+            &Path::rectangle(position, size),
+            Stroke::default().with_color(style::BOUNDARY).with_width(1.),
+        );
+        frame.fill_text(Text {
+            content: title.into(),
+            position: position + Vector::new(8., 12.),
+            color: style::INK,
+            size: 13.into(),
+            ..Default::default()
+        });
+    }
+    // Selection paint and handles remain live foreground data, including when
+    // the underlying background cache is reused after an edit.
+    frame.stroke(
+        &Path::rectangle(Point::new(29. + shift, 55.), Size::new(122., 78.)),
+        Stroke::default().with_color(style::TEAL).with_width(2.),
+    );
+    frame.fill_rectangle(Point::new(26. + shift, 52.), Size::new(6., 6.), style::TEAL);
+    frame.fill_text(Text {
+        content: if changed {
+            "Edited connection"
+        } else {
+            "Connection"
+        }
+        .into(),
+        position: Point::new(116., 113.),
+        color: style::INK,
+        size: 11.into(),
+        ..Default::default()
+    });
+}
+
+fn warning(frame: &mut Frame, size: Size) {
+    frame.fill_rectangle(
+        Point::new(8., 8.),
+        Size::new((size.width - 16.).max(0.), 30.),
+        Color::WHITE,
+    );
+    frame.fill_text(Text {
+        content: "1 connection route needs attention".into(),
+        position: Point::new(16., 15.),
+        color: style::MUTED,
+        size: 12.into(),
+        ..Default::default()
+    });
+}
+
+fn legacy_geometry(
+    renderer: &Renderer,
+    size: Size,
+    zoom: f32,
+    pan: Vector,
+    changed: bool,
+) -> Vec<canvas::Geometry> {
+    let mut combined = Frame::new(renderer, size);
+    legacy_background(&mut combined, size, zoom, pan);
+    foreground(&mut combined, zoom, pan, changed);
+    let mut overlay = Frame::new(renderer, size);
+    warning(&mut overlay, size);
+    vec![combined.into_geometry(), overlay.into_geometry()]
+}
+
+fn cached_geometry(
+    grid: &Grid,
+    renderer: &Renderer,
+    size: Size,
+    zoom: f32,
+    pan: Vector,
+    changed: bool,
+) -> Vec<canvas::Geometry> {
+    let background = grid.draw(renderer, size, zoom, pan);
+    let mut content = Frame::new(renderer, size);
+    foreground(&mut content, zoom, pan, changed);
+    let mut overlay = Frame::new(renderer, size);
+    warning(&mut overlay, size);
+    vec![background, content.into_geometry(), overlay.into_geometry()]
+}
+
+fn pixels(renderer: &mut Renderer, size: Size, geometry: Vec<canvas::Geometry>) -> Vec<u8> {
+    // Keep physical screenshot dimensions and renderer viewport consistent even
+    // for fractional canvas bounds; the geometry itself keeps its exact size.
+    let physical = Size::new(size.width.ceil() as u32, size.height.ceil() as u32);
+    renderer.reset(Rectangle::with_size(Size::new(
+        physical.width as f32,
+        physical.height as f32,
+    )));
+    for layer in geometry {
+        renderer.draw_geometry(layer);
+    }
+    let pixels = Headless::screenshot(renderer, physical, 1., style::BG);
+    assert_eq!(
+        pixels.len(),
+        physical.width as usize * physical.height as usize * 4
+    );
+    pixels
+}
+
+fn assert_same_pixels(expected: &[u8], actual: &[u8], label: &str) {
+    assert_eq!(expected.len(), actual.len(), "{label}: dimensions");
+    let differing = expected
+        .as_chunks::<4>()
+        .0
+        .iter()
+        .zip(actual.as_chunks::<4>().0)
+        .filter(|(a, b)| a != b)
+        .count();
+    assert_eq!(differing, 0, "{label}: changed RGBA pixels");
+}
+
+#[tokio::test]
+async fn cached_background_preserves_pixels_and_live_foreground_across_camera_and_size_changes() {
+    let mut renderer = renderer().await;
+    let grid = Grid::default();
+    let original = Size::new(320., 240.);
+    let threshold = 14. / 24.;
+    for (label, size, zoom, pan) in [
+        ("origin", original, 1., Vector::ZERO),
+        ("positive pan", original, 1., Vector::new(17., 11.)),
+        ("negative pan", original, 1., Vector::new(-17., -11.)),
+        ("fractional pan", original, 1., Vector::new(-17.25, 11.5)),
+        ("zoom zero pan", original, 1.25, Vector::ZERO),
+        ("below threshold", original, threshold - 0.001, Vector::ZERO),
+        ("at threshold", original, threshold, Vector::ZERO),
+        ("above threshold", original, threshold + 0.001, Vector::ZERO),
+        ("width resize", Size::new(327., 240.), 1., Vector::ZERO),
+        ("height resize", Size::new(327., 247.), 1., Vector::ZERO),
+        ("return size", original, 1., Vector::ZERO),
+        (
+            "fractional bounds",
+            Size::new(319.25, 239.5),
+            1.,
+            Vector::new(-0.5, 0.25),
+        ),
+    ] {
+        let old = legacy_geometry(&renderer, size, zoom, pan, false);
+        let expected = pixels(&mut renderer, size, old);
+        let layers = cached_geometry(&grid, &renderer, size, zoom, pan, false);
+        let actual = pixels(&mut renderer, size, layers);
+        assert_same_pixels(&expected, &actual, label);
+        let builds = grid.builds.get();
+        let reused = cached_geometry(&grid, &renderer, size, zoom, pan, false);
+        let reused = pixels(&mut renderer, size, reused);
+        assert_same_pixels(&expected, &reused, label);
+        assert_eq!(grid.builds.get(), builds, "{label}: screenshot reuse");
+
+        let edited_old = legacy_geometry(&renderer, size, zoom, pan, true);
+        let edited_expected = pixels(&mut renderer, size, edited_old);
+        assert_ne!(
+            expected, edited_expected,
+            "{label}: edit must visibly change foreground"
+        );
+        let edited = cached_geometry(&grid, &renderer, size, zoom, pan, true);
+        let edited = pixels(&mut renderer, size, edited);
+        assert_same_pixels(&edited_expected, &edited, label);
+        assert_eq!(
+            grid.builds.get(),
+            builds,
+            "{label}: foreground edit must reuse grid"
+        );
+    }
+}
+
+#[tokio::test]
+async fn actual_canvas_keeps_background_cached_while_selection_and_revision_change() {
+    use super::super::{Context, DiagramCanvas, State};
+    let mut renderer = renderer().await;
+    let mut project = Project::empty();
+    let a = project
+        .add_element(Kind::Entity, Layer::Oa, "Sensor", None)
+        .unwrap();
+    let b = project
+        .add_element(Kind::Actor, Layer::Oa, "Controller", None)
+        .unwrap();
+    let diagram = project.ensure_diagram(Layer::Oa);
+    project.diagrams.get_mut(&diagram).unwrap().projection = ProjectionKind::Overview;
+    let node = project.place(diagram, a, Position { x: 20., y: 50. });
+    project.place(diagram, b, Position { x: 100., y: 160. });
+    project.relate(RelationKind::CommunicationMean, "Link", a, b);
+    let mut canvas = DiagramCanvas {
+        selection: None,
+        allocation: None,
+        project: &project,
+        view_index: None,
+        diagram,
+        selected: a,
+        navigation_focus: None,
+        zoom: 0.75,
+        pan: Vector::ZERO,
+        context: Context {
+            document: project.id,
+            diagram,
+            revision: 0,
+            epoch: 0,
+        },
+        selected_bend: None,
+        selected_attachment: None,
+        editable: true,
+        placing: false,
+        connection: None,
+    };
+    let state = State::default();
+    let size = Size::new(360., 280.);
+    let bounds = Rectangle::with_size(size);
+    let draw = |canvas: &DiagramCanvas<'_>, renderer: &Renderer, bounds| {
+        canvas::Program::draw(
+            canvas,
+            &state,
+            renderer,
+            &crate::style::theme(),
+            bounds,
+            mouse::Cursor::Unavailable,
+        )
+    };
+    let layers = draw(&canvas, &renderer, bounds);
+    assert_eq!(layers.len(), 3, "background, scene, warning overlay");
+    let original = pixels(&mut renderer, size, layers);
+    assert_eq!(state.grid.builds.get(), 1);
+    canvas.selected = b;
+    let layers = draw(&canvas, &renderer, bounds);
+    let selected = pixels(&mut renderer, size, layers);
+    assert_ne!(original, selected, "selection must remain live");
+    assert_eq!(state.grid.builds.get(), 1);
+    let mut changed = project.clone();
+    changed
+        .diagrams
+        .get_mut(&diagram)
+        .unwrap()
+        .nodes
+        .get_mut(&node)
+        .unwrap()
+        .position
+        .x += 30.;
+    canvas.project = &changed;
+    canvas.context.revision += 1;
+    let layers = draw(&canvas, &renderer, bounds);
+    let moved = pixels(&mut renderer, size, layers);
+    assert_ne!(selected, moved, "new model revision must remain live");
+    assert_eq!(state.grid.builds.get(), 1);
+    canvas.pan.x = -0.25;
+    let _ = draw(&canvas, &renderer, bounds);
+    assert_eq!(state.grid.builds.get(), 2);
+    let _ = draw(
+        &canvas,
+        &renderer,
+        Rectangle::with_size(Size::new(361., 280.)),
+    );
+    assert_eq!(state.grid.builds.get(), 3);
+}

crates/oa-desktop/src/diagram/work_drag.rs

@@ -243,6 +243,21 @@ impl canvas::Program<Message> for WorkFeedback<'_> {
         let Some(frozen) = &feedback.frozen else {
             return vec![];
         };
+        if let Some(delta) = feedback.ghost_delta {
+            for region in &frozen.moving {
+                let top = Point::new(
+                    (region.x + delta.x) * self.0.zoom + self.0.pan.x,
+                    (region.y + delta.y) * self.0.zoom + self.0.pan.y,
+                );
+                frame.stroke(
+                    &Path::rectangle(
+                        top,
+                        iced::Size::new(region.width * self.0.zoom, region.height * self.0.zoom),
+                    ),
+                    Stroke::default().with_color(color).with_width(2.),
+                );
+            }
+        }
         for index in &feedback.targets {
             let target = &frozen.targets[*index];
             let region = target.region;

docs/language.html

@@ -2702,7 +2702,19 @@ performer change with diagram placement. The preview MUST identify the
 destination and preserve readable work and destination identity. Destination
 identity is shown outside the canvas, independently of explanatory or refusal
 text. The outlined target's hit region remains fixed throughout the gesture;
-feedback MUST NOT obscure the work or change its pointer-relative placement.
+feedback MUST NOT obscure the work. Preserve pointer-relative placement when
+the requested position is valid. When an outgoing drop would leave work
+overlapping its former performer, the editor MAY propose a minimal grid-aligned
+translation through a crossed performer boundary, with one grid unit of
+clearance. It MUST preview that exact position, translate the complete affected
+work group rigidly, and recheck all semantic and collision constraints on release.
+It MUST NOT move unrelated placements or search arbitrary free space. If no
+proposal is valid, a pointer-following outline MAY accompany the last valid
+preview; that retained preview MUST NOT authorize a refused release.
+Outgoing work headers MAY be partly outside the viewport provided each retains
+at least a 24-by-24 logical-pixel grab region. Releasing the pointer outside the
+viewport still cancels. Other assignment and Arrange gestures retain their
+complete-header visibility requirement.
 A clean click selects without applying unrelated drafts. A refused work press
 with an unapplied property draft MUST preserve its text, caret and focused
 editor. An accepted drag is one atomic model/source/history transaction:

docs/language.rst

@@ -2128,7 +2128,19 @@ performer change with diagram placement. The preview MUST identify the
 destination and preserve readable work and destination identity. Destination
 identity is shown outside the canvas, independently of explanatory or refusal
 text. The outlined target's hit region remains fixed throughout the gesture;
-feedback MUST NOT obscure the work or change its pointer-relative placement.
+feedback MUST NOT obscure the work. Preserve pointer-relative placement when
+the requested position is valid. When an outgoing drop would leave work
+overlapping its former performer, the editor MAY propose a minimal grid-aligned
+translation through a crossed performer boundary, with one grid unit of
+clearance. It MUST preview that exact position, translate the complete affected
+work group rigidly, and recheck all semantic and collision constraints on release.
+It MUST NOT move unrelated placements or search arbitrary free space. If no
+proposal is valid, a pointer-following outline MAY accompany the last valid
+preview; that retained preview MUST NOT authorize a refused release.
+Outgoing work headers MAY be partly outside the viewport provided each retains
+at least a 24-by-24 logical-pixel grab region. Releasing the pointer outside the
+viewport still cancels. Other assignment and Arrange gestures retain their
+complete-header visibility requirement.
 A clean click selects without applying unrelated drafts. A refused work press
 with an unapplied property draft MUST preserve its text, caret and focused
 editor. An accepted drag is one atomic model/source/history transaction:

harness/STATE.md

@@ -25,7 +25,13 @@ the current code includes that one-line correction. The original compile failed
 before running tests. The first combined compile at `897d9f04` subsequently
 found a missing `text_editor` import in the Allocation Text Apply regression;
 the current source includes that one-line correction too. Both failures remain
-recorded in the source handoff. Corrected combined execution remains pending.
+recorded in the source handoff. The subsequent full test run at `8ddfadf4`
+failed the mounted State picker fixture: added selection controls invalidated
+its canvas-relative clicks. Source successor `a9cd364eacbbffa0693bab05b5a2b65f9d105535`
+measures an identified fixed-height picker slot and checks Escape capture,
+retaining the exact preservation/reopen/Place/Undo assertions. The source
+handoff links the preserved failed and interrupted attempts. Corrected combined
+Windows execution and package acceptance remain pending.
 
 Live build, final-source and publication results belong in
 [issue37](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/37).

harness/drag-out-20260925.md

@@ -0,0 +1,88 @@
+# Outgoing allocation dragging
+
+Scope: [issue 40](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/40),
+based on published Windows source `715036e132677dd2bc2fb37ed316d93dc9987aec`.
+This contribution is not integrated release acceptance. User requirements remain
+in `PROJECT_GOAL.md`; this note records a revision to derived interaction policy.
+
+## Reproduction and cause
+
+The released executable SHA256
+`2c03bd6cc3f1110c219e4f57ab94874a121590f83779239a93289b7170664399`
+opened a copied Allocation/Process companion fixture on Windows. At 1440x900,
+72% Fit, the OA assign view's X-receive was dragged from window (486,546) to
+(365,546), just beyond A's left edge. It remained assigned at its original
+position, reporting enlarged card overlap. A control drag to (625,572) removed
+assignment; Undo restored the original scene. These are actual native end-state
+observations; intermediate jitter was diagnosed from source, not frame capture.
+
+Frozen targets resolve from the pointer, while placement retains its grab
+offset. The pointer therefore leaves its performer before the full work card
+does. Former parent/child intersection becomes unrelated overlap after removing
+allocation. Refused motion previously cleared the preview and redrew the saved
+scene. Additionally, whole-header viewport containment rejects a useful outgoing
+position in the fitted reproduction even when its model geometry is valid.
+
+## Selected policy
+
+Try exact snapped pointer placement first. Only an outgoing assignment candidate
+with a placement refusal may propose bounded source clearance: move the entire
+captured work footprint through a crossed frozen source boundary, clearing the
+post-removal source enclosure by one 10-world-unit grid cell. Consider at most
+four directions, ordered by press-to-pointer boundary-crossing fraction and a
+fixed direction tie-break. Existing placement, collision, semantic, exact-command
+and source/history admission remain authoritative. No neighbor is moved, no
+general packing/search occurs, and no semantic refusal is overridden.
+
+The accepted/candidate semantic indexes are reused during fallback projections.
+Outgoing headers may be partly clipped but each must retain a 24x24 logical-pixel
+grab region. Other assignment and Arrange visibility rules remain unchanged.
+The exact corrected candidate is previewed; release recomputes it. Blocked
+in-bounds motion retains its last admitted scene and adds an orange pointer
+outline. This display state confers no permission to commit on refused release.
+Cancel, outside release and gesture invalidation retire it normally.
+
+Rejected alternatives: retaining a moving outline alone leaves the boundary
+dead band; allowing unrelated overlap makes unassigned work look allocated;
+general auto-layout changes unrelated placement and makes drag intent harder to
+predict. The previous unconditional pointer-offset rule is narrowed in
+`docs/language.rst` and its HTML copy. Real neighboring-card collisions and
+insufficient visible grab area can still refuse a drop.
+
+## Verification status
+
+Independent source diagnosis and repair critique found no semantic/stale/cancel
+bypass. Review exposed the remaining whole-header camera restriction and an
+obsolete retained-preview assertion; both were revised. Added checks cover
+OA/SA boundary clearance, corners, source shrinkage, rigid descendants/groups,
+real App frame-by-frame input, exact source/history, cancellation, blocked release
+and outgoing grab-area boundaries. At clean source
+`1a669130fb6d2b65279aab3847e966a1a282c191`, the Windows allocation-drag
+suite passes 121 tests (none failed or ignored; 1,424 filtered out), strict
+desktop all-target Clippy passes, and the normal desktop development build
+passes. [Raw results and reproduction commands](experiments/drag-out-20260925/README.md)
+preserve the source, platform, failed attempts and exact scope. These checks do
+not prove native usability. Computer Use was stopped with the physical Escape
+key before the changed executable could be inspected. Fitted-view dragging,
+clipped-card identification/regrabbing, native Undo/Redo and Save/reopen remain
+unverified. The issue remains open; no integration or release acceptance follows
+from the targeted gates.
+
+Test-only successor `24b1eab07d306d8cb091bb46f7daf9f027a8f1c0` additionally
+checks an actual fallback blocked by unrelated work, including preservation of
+an existing redo branch, and an outgoing move while an allocated sibling keeps
+the source enclosure expanded. Both run for OA and SA. All 123 allocation-drag
+tests and strict desktop Clippy pass at that successor. Fresh independent review
+confirms those tests exercise their claimed invariants, with no material source
+finding in this scope. The same linked evidence includes the new logs and review;
+production code and native-acceptance limits remain unchanged.
+
+The first build attempt failed before tests because the sparse checkout omitted
+`build/windows_manifest.rs`; restoring the tracked build directory corrected the
+checkout. The local drive initially had about 22 MB free. Git sparse checkout and
+Cargo's package-scoped cleanup of inactive desktop artifacts recovered capacity.
+Automatic review rejected recursive deletion of the extracted preview; it was
+left intact. No published package or unique evidence was deleted.
+The second attempt also exposed omitted tracked harness fixtures and a `Self`
+typo in a standalone test helper; both were corrected before the passing run.
+That failed compiler process was terminated after its errors were captured.

harness/experiments/architecture-perf-20260925/.gitattributes

@@ -0,0 +1 @@
+*.log -text

harness/experiments/architecture-perf-20260925/README.md

@@ -0,0 +1,91 @@
+# Small architecture diagram CPU investigation
+
+Question: does core projection/routing explain [issue 44's low FPS](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/44)
+with roughly eight architecture cards? This experiment narrows that question;
+it neither reproduces native frame rate nor establishes a complete cause.
+
+## Workload and source
+
+The screenshot uses names from `examples/release1`. Its exact model, projection,
+camera and authored geometry are unavailable. The probe loads the unchanged
+`examples/release1/model.json`, measures its five saved views, and constructs a
+clearly labeled eight-card SA Overview approximation using those semantic
+elements. Approximate coordinates and stable placement IDs are in the probe;
+it has 8 projected nodes, 6 ports and 13 projected edges. It is not a recovered
+copy of the user's diagram. All data changes occur in memory.
+
+Source: `24b1eab07d306d8cb091bb46f7daf9f027a8f1c0`; core, manifest and lockfile
+are unchanged from the drag contribution's `1a669130` production source.
+Windows 10.0.26200, Rust 1.98.1, x86_64-pc-windows-gnullvm, LLVM-MinGW
+20260908 UCRT, reported CPU Intel Core i7-10870H with 4 exposed cores/threads.
+The probe was optimized with `-O` and linked to the existing **unoptimized
+development-profile core library** used by the completed desktop test build.
+This distinction matters: optimizing the driver does not optimize that library.
+The desktop test process had completed before measurement; no Cargo compilation
+was started until after measurement. Other operating-system workloads were not
+controlled, so outliers are retained rather than interpreted as stable capacity.
+
+## Method and results
+
+Each phase gets 3 warmups and 40 timed samples, with returned values passed to
+`black_box`. Reported p50/p95 select sorted index `ceil((n-1)*p)` as implemented
+in the source. Returned output destruction is outside each timed phase. Diagram
+movement uses a deterministic small delta sequence and the existing descendant
+and authored-route translation APIs. Index creation, projection, routing, and
+combined movement preparation are measured separately. The probe does not model
+allocation transaction admission or an Iced frame.
+
+For the eight-card approximation, `performance-01.log` records:
+
+| Phase | p50 ms | p95 ms | max ms |
+| --- | ---: | ---: | ---: |
+| Reused-index projection | 0.3885 | 0.7550 | 1.2965 |
+| Fresh-index projection | 1.7135 | 2.7022 | 4.2204 |
+| Settled routing | 2.4525 | 4.4617 | 4.7735 |
+| Moved routing | 3.1907 | 4.4781 | 4.5672 |
+| Movement preparation + projection + routing | 4.2640 | 6.8259 | 8.8052 |
+
+This workload does not expose severe core latency sufficient by itself to
+explain very low FPS. It does not rule out different authored routes, allocation
+admission, hardware/rendering, or the user's exact scene. Repeated fresh-index
+projection has a measurable cost, but no change is justified solely by this
+small sample. No FPS or performance-fix claim follows.
+
+## Source observations and next discriminating measurement
+
+Independent read-only hot-path review found that `DiagramCanvas::scene` already
+caches projection and routing by semantic context and transient geometry.
+Ordinary node movement changes preview geometry and routes the full view;
+route gestures use `route_edge_preview`. Ordinary hover need not reroute.
+
+`diagram/port_labels.rs` requests redraw on every mouse event, including when
+no tooltip is visible. `DiagramCanvas::draw` rebuilds geometry and each dot-grid
+circle on every draw. At a 1900x660 canvas this yields about 2,240 circles at
+zoom 1 and 6,528 at minimum spacing. Scene caching does not cache that geometry.
+`views.rs` also performs an unindexed `project_view` during app view rebuilding;
+legacy node-motion redraw does not itself require that full UI rebuild.
+
+Next, measure actual canvas draw/frame costs independently for idle hover, pan,
+ordinary node drag and allocation drag, with grid generation separated from
+node/edge/text rendering and frame presentation. Compare the same scene/camera
+and renderer before changing production code. Native automation was stopped
+with Escape; no GPU/frame measurement was attempted in this experiment. Live
+ownership and subsequent results belong to issue 44.
+
+## Reproduction
+
+Build `oa-core` at the identified source with the stated Windows toolchain, then
+compile this standalone probe against that exact library and matching dependency
+directory. For a fresh standard Cargo development build:
+
+```powershell
+cargo build --locked -p oa-core
+rustc --edition=2024 -O harness/experiments/architecture-perf-20260925/architecture_perf_probe.rs --extern oa_core=target/debug/liboa_core.rlib -L dependency=target/debug/deps -C linker=clang.exe -o architecture_perf_probe.exe
+./architecture_perf_probe.exe examples/release1/model.json 40
+```
+
+The actual run linked `target/debug/deps/liboa_core-2f3c5174cb6398fd.rlib`
+and used the same dependency directory. Set the linker/runtime PATH as required
+by the Windows toolchain. Compiler flags, core profile, machine load and fixture
+all affect timings; preserve them when comparing candidates. This standalone
+probe is experimental evidence, not a production dependency or a timing test.

harness/experiments/architecture-perf-20260925/architecture_perf_probe.rs

@@ -0,0 +1,166 @@
+//! Local-only CPU diagnosis. Does not measure native FPS, canvas redraw, or GPU.
+//! Usage: architecture_perf_probe.exe PATH_TO_RELEASE1_MODEL_JSON [SAMPLES=40]
+use oa_core::{persistence, projection, routing, view_options::ViewIndex, *};
+use std::{collections::BTreeMap, hint::black_box, time::Instant};
+
+fn measure<T>(label: &str, samples: usize, mut f: impl FnMut(usize) -> T) {
+    for i in 0..3 {
+        black_box(f(i));
+    }
+    let mut ms = Vec::with_capacity(samples);
+    for i in 0..samples {
+        let start = Instant::now();
+        let output = black_box(f(i));
+        ms.push(start.elapsed().as_secs_f64() * 1000.0);
+        drop(output); // Exclude destruction consistently from each timed phase.
+    }
+    ms.sort_by(f64::total_cmp);
+    let percentile = |p: f64| ms[((samples - 1) as f64 * p).ceil() as usize];
+    println!(
+        "{label}: n={samples} p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+        percentile(0.5),
+        percentile(0.95),
+        ms[samples - 1]
+    );
+}
+
+fn probe(p: &Project, d: &Diagram, samples: usize) {
+    let index = ViewIndex::new(p);
+    let view = projection::project_diagram_with_index(p, d, &index);
+    println!(
+        "\nview={} projection={:?} nodes={} ports={} edges={}",
+        d.name,
+        d.projection,
+        view.nodes.len(),
+        view.ports.len(),
+        view.edges.len()
+    );
+    measure("index_new", samples, |_| ViewIndex::new(black_box(p)));
+    measure("projection_reused_index", samples, |_| {
+        projection::project_diagram_with_index(black_box(p), black_box(d), black_box(&index))
+    });
+    measure("projection_fresh_index", samples, |_| {
+        projection::project_diagram(black_box(p), black_box(d))
+    });
+    measure("routing_settled", samples, |_| {
+        routing::route_diagram(black_box(p), black_box(d), black_box(&view))
+    });
+    // Deterministic slight motion of the first root card. Includes the same
+    // descendant/route translation as legacy single-card canvas drag. This is
+    // presentation-only, not the allocation transaction pipeline.
+    let Some(root) = view.nodes.iter().find(|n| n.visual_parent.is_none()) else {
+        return;
+    };
+    println!("moving_root={} element={}", root.id, p.named(root.element));
+    let mut moved = projection::descendant_nodes(p, d.id, root.id);
+    moved.push(root.id);
+    let make_moved = |i: usize| {
+        let delta = Position {
+            x: (i % 21) as f32 * 3.0,
+            y: (i % 11) as f32 * 2.0,
+        };
+        let mut preview = d.clone();
+        let deltas = moved
+            .iter()
+            .map(|id| (*id, delta))
+            .collect::<BTreeMap<_, _>>();
+        for route in projection::translated_routes(p, d, &deltas) {
+            if let Some(stored) = preview.routes.iter_mut().find(|r| r.edge == route.edge) {
+                *stored = route;
+            } else {
+                preview.routes.push(route);
+            }
+        }
+        for id in &moved {
+            if let Some(n) = preview.nodes.get_mut(id) {
+                n.position.x += delta.x;
+                n.position.y += delta.y;
+            }
+        }
+        preview
+    };
+    let previews = (0..samples.max(3)).map(make_moved).collect::<Vec<_>>();
+    let projected = previews
+        .iter()
+        .map(|d| projection::project_diagram_with_index(p, d, &index))
+        .collect::<Vec<_>>();
+    measure("moved_projection", samples, |i| {
+        projection::project_diagram_with_index(p, black_box(&previews[i]), &index)
+    });
+    measure("moved_routing", samples, |i| {
+        routing::route_diagram(p, black_box(&previews[i]), black_box(&projected[i]))
+    });
+    measure("moved_prepare_projection_routing", samples, |i| {
+        let preview = make_moved(i);
+        let view = projection::project_diagram_with_index(p, &preview, &index);
+        routing::route_diagram(p, &preview, &view)
+    });
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args = std::env::args().collect::<Vec<_>>();
+    let path = args
+        .get(1)
+        .ok_or("usage: architecture_perf_probe PATH [SAMPLES]")?;
+    let samples = args
+        .get(2)
+        .map(|s| s.parse::<usize>())
+        .transpose()?
+        .unwrap_or(40)
+        .max(1);
+    let p = persistence::decode(&std::fs::read(path)?)?;
+    println!(
+        "CPU-only probe; samples={samples}; fixture={path}; elements={} relations={}",
+        p.elements.len(),
+        p.relations.len()
+    );
+    for d in p.diagrams.values() {
+        probe(&p, d, samples);
+    }
+    // Approximation of the reported eight-card screenshot, not an exact repro:
+    // fixture semantics, Overview projection, synthetic positions/card sizes.
+    let mut approx = p.clone();
+    let id: Id = "f0440000-0000-4000-8000-000000000001".parse()?;
+    approx.diagrams.insert(
+        id,
+        Diagram {
+            id,
+            alias: "fps44_approx_overview".into(),
+            name: "APPROXIMATION eight-card SA Overview".into(),
+            description: "Synthetic positions, not user geometry".into(),
+            layer: Layer::Sa,
+            projection: ProjectionKind::Overview,
+            view_options: Default::default(),
+            nodes: BTreeMap::new(),
+            routes: vec![],
+            layout: None,
+        },
+    );
+    for (ordinal, (alias, x, y)) in [
+        ("sa_assessment_procedure", 30., 240.),
+        ("sa_triage", 510., 240.),
+        ("sa_control", 990., 240.),
+        ("sa_technician", 530., 440.),
+        ("sa_assess", 1490., 240.),
+        ("sa_repair", 1030., 440.),
+        ("sa_confirm", 1530., 440.),
+        ("sa_reset", 30., 440.),
+    ]
+    .into_iter()
+    .enumerate()
+    {
+        let element = approx
+            .elements
+            .values()
+            .find(|e| e.alias == alias)
+            .ok_or_else(|| format!("missing alias {alias}"))?
+            .id;
+        let generated = approx.place(id, element, Position { x, y });
+        let diagram = approx.diagrams.get_mut(&id).unwrap();
+        let mut node = diagram.nodes.remove(&generated).unwrap();
+        node.id = format!("f0440000-0000-4000-8000-{:012}", ordinal + 2).parse()?;
+        diagram.nodes.insert(node.id, node);
+    }
+    probe(&approx, &approx.diagrams[&id], samples);
+    Ok(())
+}

harness/experiments/architecture-perf-20260925/context.json

@@ -0,0 +1,11 @@
+{
+  "source": "24b1eab07d306d8cb091bb46f7daf9f027a8f1c0",
+  "core_profile": "dev unoptimized",
+  "driver_optimization": "rustc -O",
+  "samples_per_phase": 40,
+  "warmups_per_phase": 3,
+  "rlib_sha256": "E10C81BF28A33CD0FB6C4C26884CFFA480EF05328E78BCDB138DD4B635B2531C",
+  "fixture_sha256": "EF0EF4006C3E09D5DB6E1B621256B3F7D6642F3A7B09CC34607CFBCCA830C727",
+  "driver_exe_sha256": "4C66E9CDE4F08D6DFD2A0DC3DBF1A80B97E340F3F22CA001A76301F06F47C2E2",
+  "native_fps_measured": false
+}

harness/experiments/architecture-perf-20260925/performance-01.log

@@ -0,0 +1,61 @@
+CPU-only probe; samples=40; fixture=.local/drag-out-01a0d6fd/examples/release1/model.json; elements=94 relations=62
+
+view=1 · OA responsibility and repair traffic projection=Allocation nodes=6 ports=0 edges=3
+index_new: n=40 p50_ms=1.0106 p95_ms=2.0583 max_ms=2.0910
+projection_reused_index: n=40 p50_ms=0.5702 p95_ms=1.2320 max_ms=1.3490
+projection_fresh_index: n=40 p50_ms=1.5505 p95_ms=3.6681 max_ms=5.1533
+routing_settled: n=40 p50_ms=0.1944 p95_ms=0.3391 max_ms=0.4246
+moving_root=3191e05c-1c7f-5f0e-beb0-5f3bded54c48 element=Control room
+moved_projection: n=40 p50_ms=0.4848 p95_ms=1.2745 max_ms=1.5797
+moved_routing: n=40 p50_ms=0.1994 p95_ms=0.7971 max_ms=1.1414
+moved_prepare_projection_routing: n=40 p50_ms=0.9250 p95_ms=2.6847 max_ms=10.4908
+
+view=5 · SA pressure supervision projection=StateMachine { machine: 132b3f28-3f88-5327-9868-8c8b645ed412 } nodes=5 ports=0 edges=3
+index_new: n=40 p50_ms=0.9602 p95_ms=2.1394 max_ms=2.4512
+projection_reused_index: n=40 p50_ms=0.1697 p95_ms=0.7629 max_ms=1.1780
+projection_fresh_index: n=40 p50_ms=1.1189 p95_ms=2.6324 max_ms=3.3912
+routing_settled: n=40 p50_ms=0.7063 p95_ms=1.0812 max_ms=1.1149
+moving_root=a676fbb9-0833-59a8-98cf-a10d8f4b7434 element=Pressure supervision
+moved_projection: n=40 p50_ms=0.1565 p95_ms=0.3445 max_ms=0.3790
+moved_routing: n=40 p50_ms=0.6113 p95_ms=1.3199 max_ms=1.3733
+moved_prepare_projection_routing: n=40 p50_ms=0.8259 p95_ms=1.7640 max_ms=2.1752
+
+view=2 · SA service boundary and functions projection=Allocation nodes=6 ports=6 edges=3
+index_new: n=40 p50_ms=0.7820 p95_ms=3.4180 max_ms=6.8439
+projection_reused_index: n=40 p50_ms=0.7938 p95_ms=1.9946 max_ms=2.1411
+projection_fresh_index: n=40 p50_ms=2.0597 p95_ms=3.4554 max_ms=3.6616
+routing_settled: n=40 p50_ms=0.1478 p95_ms=0.7886 max_ms=1.0081
+moving_root=8345c76a-8d85-5c31-902e-ec1cd33ed4a3 element=Pressure coordination service
+moved_projection: n=40 p50_ms=0.6914 p95_ms=1.5286 max_ms=1.8658
+moved_routing: n=40 p50_ms=0.1862 p95_ms=0.5658 max_ms=2.8924
+moved_prepare_projection_routing: n=40 p50_ms=1.1724 p95_ms=3.1806 max_ms=4.2620
+
+view=4 · SA mission and included capability projection=Capabilities nodes=4 ports=1 edges=3
+index_new: n=40 p50_ms=0.6879 p95_ms=1.3582 max_ms=1.5266
+projection_reused_index: n=40 p50_ms=0.1562 p95_ms=0.6767 max_ms=1.0102
+projection_fresh_index: n=40 p50_ms=1.2929 p95_ms=2.3543 max_ms=4.0762
+routing_settled: n=40 p50_ms=0.2553 p95_ms=1.4389 max_ms=1.6677
+moving_root=069a3fb3-077c-59d8-91da-27b0665143c7 element=Assess an alarm
+moved_projection: n=40 p50_ms=0.1243 p95_ms=0.1928 max_ms=0.2212
+moved_routing: n=40 p50_ms=0.2271 p95_ms=0.6733 max_ms=1.2408
+moved_prepare_projection_routing: n=40 p50_ms=0.5542 p95_ms=1.3344 max_ms=1.8957
+
+view=3 · SA service conversation only projection=Allocation nodes=6 ports=6 edges=1
+index_new: n=40 p50_ms=0.9618 p95_ms=1.6890 max_ms=2.0995
+projection_reused_index: n=40 p50_ms=0.6661 p95_ms=2.3388 max_ms=2.6429
+projection_fresh_index: n=40 p50_ms=2.3913 p95_ms=4.1941 max_ms=4.8120
+routing_settled: n=40 p50_ms=0.0660 p95_ms=0.2156 max_ms=0.6289
+moving_root=40210589-69f7-5209-b329-10bb83cf615c element=Field technician
+moved_projection: n=40 p50_ms=0.5527 p95_ms=1.1239 max_ms=1.1362
+moved_routing: n=40 p50_ms=0.0495 p95_ms=0.1771 max_ms=0.2209
+moved_prepare_projection_routing: n=40 p50_ms=0.7963 p95_ms=4.1835 max_ms=6.7551
+
+view=APPROXIMATION eight-card SA Overview projection=Overview nodes=8 ports=6 edges=13
+index_new: n=40 p50_ms=0.7487 p95_ms=1.9597 max_ms=2.2005
+projection_reused_index: n=40 p50_ms=0.3885 p95_ms=0.7550 max_ms=1.2965
+projection_fresh_index: n=40 p50_ms=1.7135 p95_ms=2.7022 max_ms=4.2204
+routing_settled: n=40 p50_ms=2.4525 p95_ms=4.4617 max_ms=4.7735
+moving_root=f0440000-0000-4000-8000-000000000002 element=Assess an alarm procedure
+moved_projection: n=40 p50_ms=0.4691 p95_ms=0.8354 max_ms=1.0408
+moved_routing: n=40 p50_ms=3.1907 p95_ms=4.4781 max_ms=4.5672
+moved_prepare_projection_routing: n=40 p50_ms=4.2640 p95_ms=6.8259 max_ms=8.8052

harness/experiments/drag-out-20260925/.gitattributes

@@ -0,0 +1 @@
+*.log -text

harness/experiments/drag-out-20260925/README.md

@@ -0,0 +1,74 @@
+# Outgoing allocation drag evidence
+
+Contribution source: `1a669130fb6d2b65279aab3847e966a1a282c191`, based on
+published preview `715036e132677dd2bc2fb37ed316d93dc9987aec`.
+This is branch-specific Windows evidence for [issue 40](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/40).
+It is not acceptance of an integrated release or the complete application.
+The [decision and native baseline](../../drag-out-20260925.md) explain the repair.
+
+## Environment and commands
+
+Windows 10.0.26200, Rust/Cargo 1.98.1, host/target
+`x86_64-pc-windows-gnullvm`, LLVM 22.1.8, LLVM-MinGW 20260908 UCRT linker
+`clang.exe`, `CARGO_BUILD_JOBS=1`, `CARGO_INCREMENTAL=0`, default development
+profile. Run at the identified source with the Windows GNU LLVM toolchain and
+its linker/runtime available on PATH. A sparse checkout must include `build`
+and `harness/fixtures` as well as crates. The actual commands were:
+
+```powershell
+cargo test --locked --offline -p oa-desktop allocation_drag -- --test-threads=1
+cargo clippy --locked --offline -p oa-desktop --all-targets -- -D warnings
+cargo build --locked --offline -p oa-desktop --bin arcadia-studio
+```
+
+Offline commands require dependencies already cached. A fresh environment must
+fetch the locked dependencies first. Raw logs retain original absolute paths;
+these paths identify this run, not required directories on another machine.
+
+## Results and boundaries
+
+- Test-only successor `24b1eab07d306d8cb091bb46f7daf9f027a8f1c0` adds two
+  OA/SA App regressions: a clearance proposal blocked by unrelated work and an
+  outgoing move with a retained sibling enlarging the source enclosure.
+  `tests-04.log` passes all 123 allocation-drag tests (zero failed/ignored,
+  1,424 filtered) in 54.86s; `clippy-02.log` passes the same strict command in
+  1m27s. Production inputs are unchanged from `1a669130`; its normal binary
+  remains the native candidate. [Independent review](independent-review.md)
+  covers the source, new test design and evidence limits.
+- `tests-03.log`: 121 passed, zero failed/ignored, 1,424 filtered; 35.33 seconds
+  test execution. This is the allocation-drag subset, not the full desktop suite.
+- `clippy-01.log`: strict desktop all-target Clippy passed in 4m30s.
+- `build-01.log`: normal GUI build passed in 5m16s. The resulting local executable
+  SHA256 is `9bda1a6a1d24fdc98c7a8822400c12fea9afe1de828a82ba9273f03b99e47c07`.
+  It was staged with the published preview's `libunwind.dll` and started, but
+  Computer Use was stopped before any changed-binary native observation.
+- `context.json`: recorded source/toolchain, passing test-log and baseline-image
+  hashes, and clean source after the test run.
+- `tests-01.log`: compilation failed before tests because `build/windows_manifest.rs`
+  was excluded from the initial sparse checkout.
+- `tests-02.log`: compilation failed before tests because harness fixture files
+  were excluded and a standalone test helper used `Self` instead of `Fixture`.
+  The compiler was terminated after reporting errors; its interrupted exit is
+  preserved. The missing tracked files and typo were repaired before run 03.
+
+The tests exercise source-clearance proposals, OA/SA App event sequences,
+preview/release agreement, exact source/history, cancellation, and retained
+preview without commit authority on refused release. Existing collision and
+semantic checks still govern all proposals. Independent source review found the
+whole-header viewport restriction and obsolete preview assertion; both were
+corrected before the passing run. This is source/test review, not native review.
+
+`baseline-left-refusal.png` is an unmodified actual native capture from the
+published preview executable, SHA256
+`2c03bd6cc3f1110c219e4f57ab94874a121590f83779239a93289b7170664399`.
+In the copied Allocation companion fixture, OA assign view at 1440x900 content
+and Fit 72%, dragging X from window (486,546) to (365,546) leaves allocation and
+placement unchanged and reports overlap. A control drag to (625,572) removes
+allocation, and Undo restores it. Intermediate jitter was diagnosed from source;
+this image is end-state evidence only.
+
+Changed-binary native acceptance is still required: repeat the short fitted-view
+drag, identify and regrab the partially clipped card, check refused-motion
+feedback, Cancel and Undo/Redo, save the full bundle, close and reopen in a fresh
+process, and verify identity/allocation/placement and unchanged sibling data for
+OA and SA. Linux/WSL remains deferred by the user. No published package changed.

harness/experiments/drag-out-20260925/build-01.log

@@ -0,0 +1,5 @@
+   Compiling iced_widget v0.14.2 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\vendor\iced_widget)
+   Compiling iced v0.14.0
+   Compiling oa-core v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-core)
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `dev` profile [unoptimized] target(s) in 5m 16s

harness/experiments/drag-out-20260925/clippy-01.log

@@ -0,0 +1,6 @@
+   Compiling oa-core v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-core)
+    Checking iced_widget v0.14.2 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\vendor\iced_widget)
+   Compiling oa-server v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-server)
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Checking iced v0.14.0
+    Finished `dev` profile [unoptimized] target(s) in 4m 30s

harness/experiments/drag-out-20260925/clippy-02.log

@@ -0,0 +1,2 @@
+    Checking oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `dev` profile [unoptimized] target(s) in 1m 27s

harness/experiments/drag-out-20260925/context.json

@@ -0,0 +1,20 @@
+{
+  "source": "1a669130fb6d2b65279aab3847e966a1a282c191",
+  "platform": "Microsoft Windows 10.0.26200",
+  "compiler": [
+    "rustc 1.98.1 (48a229cea 2026-09-01)",
+    "binary: rustc",
+    "commit-hash: 48a229ceaefd4985c50990b14116b6d856af0985",
+    "commit-date: 2026-09-01",
+    "host: x86_64-pc-windows-gnullvm",
+    "release: 1.98.1",
+    "LLVM version: 22.1.8"
+  ],
+  "cargo": "cargo 1.98.1 (797e8a9bc 2026-08-05)",
+  "test_log_sha256": "8EB57F522FA0DCCA327DC13C67A9C1B14F5FAB09C5599C108C0BA6D875C78886",
+  "baseline_image_sha256": "AAF162619582018D1197D255B4BA1122747AA22703D8DEDFC7FCEFCB42AEFE38",
+  "target": "x86_64-pc-windows-gnullvm",
+  "incremental": "0",
+  "jobs": "1",
+  "working_tree_clean_after_test": true
+}

harness/experiments/drag-out-20260925/independent-review.md

@@ -0,0 +1,33 @@
+# Independent source and evidence review
+
+Fresh read-only GPT-6 Astra review, 2026-09-25. Production source
+`1a669130fb6d2b65279aab3847e966a1a282c191`; test-only successor
+`24b1eab07d306d8cb091bb46f7daf9f027a8f1c0`. No GUI actions or test execution
+were performed by this reviewer.
+
+No material correctness finding in the bounded scope:
+
+- The outgoing collision regression in `app/allocation_drag_tests.rs` proves a
+  real source-boundary crossing and unobscured OutsidePerformers target, a
+  nonempty clearance proposal, and intersection with unrelated work. Ordinary
+  placement rejects that proposal. Release preserves project, source bundle,
+  revision, snapshot identity and redo availability.
+- The retained-sibling regression first requires exact requested placement to
+  fail. The admitted correction clears the enlarged source enclosure while
+  preserving its projection, sibling allocation/placement and all other stored
+  placements. Preview/release and source Undo/Redo comparisons are exact.
+- In `app/allocation_drag.rs`, clearance remains downstream of semantic
+  admission and retries ordinary placement. Release recomputes placement and
+  passes through `finish` and document execution. No collision, stale-state or
+  retained-preview commit bypass was found.
+- The committed passing log's bytes and SHA256 match `context.json`; the
+  baseline image hash also matches. Logs support 121 passing tests, strict
+  Clippy and normal development build for the production source. They do not
+  establish execution of the two successor tests; consult the linked raw logs
+  and README for subsequent execution evidence.
+
+The review supports the source policy and test design, not native usability.
+The 24x24 visible-header threshold alone does not prove readable identity or
+practical regrabbing. Changed-binary fitted-view dragging, feedback, recovery
+and Save/reopen remain unverified. This review is not the broad final
+requirements/domain/UX/release review required by `PROJECT_GOAL.md`.

harness/experiments/drag-out-20260925/successor-context.json

@@ -0,0 +1,12 @@
+{
+  "source": "24b1eab07d306d8cb091bb46f7daf9f027a8f1c0",
+  "production_source": "1a669130fb6d2b65279aab3847e966a1a282c191",
+  "test_log": "tests-04.log",
+  "test_log_sha256": "C98E0F70D60788B484146B3C8785891888BA696130ACC4BFD7D30DA570E6B1E1",
+  "passed": 123,
+  "failed": 0,
+  "ignored": 0,
+  "filtered": 1424,
+  "native_candidate_sha256": "9BDA1A6A1D24FDC98C7A8822400C12FEA9AFE1DE828A82BA9273F03B99E47C07",
+  "native_acceptance": "unverified"
+}

harness/experiments/drag-out-20260925/tests-01.log

@@ -0,0 +1,8 @@
+   Compiling oa-core v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-core)
+error: couldn't read `crates\oa-core\../../build/windows_manifest.rs`: The system cannot find the path specified. (os error 3)
+ --> crates\oa-core\build.rs:1:1
+  |
+1 | include!("../../build/windows_manifest.rs");
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: could not compile `oa-core` (build script) due to 1 previous error

harness/experiments/drag-out-20260925/tests-02.log

@@ -0,0 +1,68 @@
+   Compiling oa-core v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-core)
+   Compiling oa-server v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-server)
+   Compiling iced_widget v0.14.2 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\vendor\iced_widget)
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+   Compiling iced v0.14.0
+error: couldn't read `C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop/../../harness/fixtures/interface-operation-probe/output/boundary-only.json`: The system cannot find the path specified. (os error 3)
+   --> crates\oa-desktop\src\app\reference_authoring\tests\mounted.rs:755:37
+    |
+755 |       let mut p = persistence::decode(include_bytes!(concat!(
+    |  _____________________________________^
+756 | |         env!("CARGO_MANIFEST_DIR"),
+757 | |         "/../../harness/fixtures/interface-operation-probe/output/boundary-only.json"
+758 | |     )))
+    | |______^
+
+error: couldn't read `C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop/../../harness/fixtures/interface-operation-probe/output/boundary-only.json`: The system cannot find the path specified. (os error 3)
+   --> crates\oa-desktop\src\behavior\scenario\usage\tests.rs:235:37
+    |
+235 |       let mut p = persistence::decode(include_bytes!(concat!(
+    |  _____________________________________^
+236 | |         env!("CARGO_MANIFEST_DIR"),
+237 | |         "/../../harness/fixtures/interface-operation-probe/output/boundary-only.json"
+238 | |     )))
+    | |______^
+
+error: couldn't read `C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop/../../harness/fixtures/interface-operation-probe/output/boundary-only.json`: The system cannot find the path specified. (os error 3)
+ --> crates\oa-desktop\src\behavior\scenario_operation_tests.rs:6:25
+  |
+6 |       persistence::decode(include_bytes!(concat!(
+  |  _________________________^
+7 | |         env!("CARGO_MANIFEST_DIR"),
+8 | |         "/../../harness/fixtures/interface-operation-probe/output/boundary-only.json"
+9 | |     )))
+  | |______^
+
+error: couldn't read `C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop/../../harness/fixtures/source7-native/base/expected-baseline.json`: The system cannot find the path specified. (os error 3)
+  --> crates\oa-desktop\src\behavior\topology\contextual_routing.rs:61:29
+   |
+61 |           persistence::decode(include_bytes!(concat!(
+   |  _____________________________^
+62 | |             env!("CARGO_MANIFEST_DIR"),
+63 | |             "/../../harness/fixtures/source7-native/base/expected-baseline.json"
+64 | |         )))
+   | |__________^
+
+error: couldn't read `C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop/../../harness/fixtures/interface-operation-probe/output/boundary-only.json`: The system cannot find the path specified. (os error 3)
+ --> crates\oa-desktop\src\semantic_review\source7_tests.rs:5:25
+  |
+5 |       persistence::decode(include_bytes!(concat!(
+  |  _________________________^
+6 | |         env!("CARGO_MANIFEST_DIR"),
+7 | |         "/../../harness/fixtures/interface-operation-probe/output/boundary-only.json"
+8 | |     )))
+  | |______^
+
+error[E0411]: cannot find struct, variant or union type `Self` in this scope
+   --> crates\oa-desktop\src\app\allocation_drag\clearance.rs:314:9
+    |
+287 |     fn fixture(layer: Layer) -> Fixture {
+    |        ------- `Self` not allowed in a function
+...
+314 |         Self {
+    |         ^^^^ `Self` is only available in impls, traits, and type definitions
+
+error: could not compile `oa-desktop` (bin "arcadia-studio" test) due to 6 previous errors
+
+Caused by:
+  process didn't exit successfully: `C:\Users\User\Documents\Git\ARCADIA-Studio\.local\toolchain\rustup\toolchains\stable-x86_64-pc-windows-gnullvm\bin\rustc.exe --crate-name arcadia_studio --edition=2024 crates\oa-desktop\src\main.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --emit=dep-info,link -C embed-bitcode=no --test --check-cfg cfg(docsrs,test) --check-cfg "cfg(feature, values())" -C metadata=5e2096130f19ead2 -C extra-filename=-c5b42126ba36cd38 --out-dir C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps -C linker=clang.exe -C strip=debuginfo -L dependency=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps --extern axum=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libaxum-ccc7aea466db9258.rlib --extern iced=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libiced-594f7d417d69ed72.rlib --extern iced_runtime=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libiced_runtime-4d31a36fe5cef0b0.rlib --extern oa_core=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\liboa_core-2f3c5174cb6398fd.rlib --extern oa_server=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\liboa_server-bb42169ca297f969.rlib --extern reqwest=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libreqwest-31ac987472fa8038.rlib --extern rfd=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\librfd-17cc7ba2db223d7b.rlib --extern serde=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libserde-60a32311146a42e4.rlib --extern serde_json=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libserde_json-da2c4f333fc47818.rlib --extern tempfile=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libtempfile-86aac28d6be16d2f.rlib --extern tokio=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libtokio-5e0ca96735e3073a.rlib --extern unicode_segmentation=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\libunicode_segmentation-85698043f7780858.rlib -L native=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\build\ring-5f8d2d20440f09b4\out -L native=C:\Users\User\Documents\Git\ARCADIA-Studio\.local\toolchain\cargo\registry\src\index.crates.io-1949cf8c6b5b557f\windows_x86_64_gnullvm-0.52.6\lib -C link-arg=C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\build\oa-desktop-307d320bbc13ccd5\out\normal-user-manifest.o` (exit code: 0xffffffff)

harness/experiments/drag-out-20260925/tests-03.log

@@ -0,0 +1,130 @@
+    Blocking waiting for file lock on build directory
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `test` profile [unoptimized] target(s) in 8m 13s
+     Running unittests src\main.rs (C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\arcadia_studio-c5b42126ba36cd38.exe)
+
+running 121 tests
+test allocation_drag::outgoing_header_retains_a_grab_region_without_requiring_full_camera_containment ... ok
+test allocation_drag::tests::allocation_artifact_and_manual_trace_cascades_are_named_and_refused ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_detects_hidden_moved_child_and_stationary_enclosure_growth ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_distributed_oa_sa_exact_scope_routes_source_history_and_anchor ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_noop_stale_tamper_target_and_all_selected_headers ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_performer_closure_does_not_acquire_incidental_semantic_root ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_preserves_existing_overlap_but_refuses_its_growth ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_preserves_roles_and_does_not_invent_unplaced_descendants ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_preserves_unrelated_folded_interior_diagnostic_boundary ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_simultaneous_roots_may_enter_each_others_vacated_bounds ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_validates_all_original_members_before_normalizing ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_checks_original_identity_and_visibility_before_normalization ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_distributed_parent_refuses_but_its_independent_leaves_can_reassign ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_finish_rejects_stale_project_and_each_tampered_result ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_normalizes_parent_child_and_assigns_unplaced_leaf_once ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_requires_non_anchor_selected_header_inside_viewport ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_unresolved_oa_role_leaf_accepts_explicit_target_but_not_outside ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_accumulates_stable_ids_and_aliases_without_partial_reuse ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_collateral_surviving_constraint_refuses_whole_semantic_candidate ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_deletes_only_own_routes_across_views_and_keeps_internal_flow ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_independent_performers_preserves_already_correct_provenance ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_source_failure_preserves_existing_history_and_retry_ids ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_unfolds_only_changed_destination_and_refuses_newly_exposed_overlap ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_uses_vacated_space_and_one_complete_route_owner_map ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_zero_delta_changes_semantics_once_and_then_is_noop ... ok
+test allocation_drag::tests::cache_plan_uses_candidate_index_and_same_pixel_different_target_changes_preview ... ok
+test allocation_drag::tests::collapsed_target_unfold_is_explicit_and_no_other_fold_changes ... ok
+test allocation_drag::tests::direct_exit_revealing_another_role_performer_has_truthful_refusal ... ok
+test allocation_drag::tests::explicit_different_performer_retains_advisory_role_warning ... ok
+test allocation_drag::tests::folded_subtree_cannot_hide_new_collision ... ok
+test allocation_drag::tests::geometry_refuses_new_overlap_bounds_and_invisible_headers_and_preserves_existing_overlap ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_detects_moved_folded_child_collision ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_detects_stationary_enclosure_growth_collision ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_distributed_root_and_performer_can_translate_rigidly ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_unrelated_folded_interiors_are_outside_diagnostic_domain ... ok
+test allocation_drag::tests::malformed_scope_wrong_projection_duplicate_placement_and_stable_id_collision_refuse ... ok
+test allocation_drag::tests::mixed_p_x_y_refuses_semantic_and_arrange_instead_of_stretching_destination ... ok
+test allocation_drag::tests::oa_communication_incompleteness_remains_advisory_without_collateral_loss ... ok
+test allocation_drag::tests::oa_sa_incoming_between_outgoing_preserve_identity_source_history_and_other_views ... ok
+test allocation_drag::tests::oa_sa_one_leaf_move_refuses_when_ancestor_regrouping_introduces_unrelated_overlap ... ok
+test allocation_drag::tests::oa_sa_one_leaf_reassignment_and_outward_move_regroup_ancestors_without_moving_sibling ... ok
+test allocation_drag::tests::oa_sa_populated_collapsed_target_accepts_room_and_refuses_collision_without_relocating_contents ... ok
+test allocation_drag::tests::oa_sa_state_owned_action_and_availability_reject_reassignment_atomically ... ok
+test allocation_drag::tests::oa_sa_unfolding_prior_hidden_overlap_refuses_even_when_insertion_does_not_collide ... ok
+test allocation_drag::tests::own_deleted_allocation_routes_may_disappear_in_every_diagram_only ... ok
+test allocation_drag::tests::role_only_same_effective_performer_is_semantic_noop_and_outgoing_refuses ... ok
+test allocation_drag::tests::sa_port_and_deferred_exchange_allocation_cascade_refuses_and_retarget_is_invalid ... ok
+test allocation_drag::tests::same_performer_readability_preserves_snapped_noop_and_allocation_identity ... ok
+test allocation_drag::tests::scope_detects_first_child_allocation_and_role_transfer_and_finish_rejects_live_edits ... ok
+test allocation_drag::tests::selected_header_visibility_allows_viewport_edge_but_refuses_clipping ... ok
+test allocation_drag::tests::snapped_noop_returns_no_command_and_keeps_source_revision_and_redo ... ok
+test allocation_drag::tests::source_budget_refusal_keeps_project_bundle_history_and_retry_identity_exact ... ok
+test allocation_drag::tests::surviving_constraint_mutation_is_refused_even_when_core_candidate_is_valid ... ok
+test allocation_drag::tests::target_presentation_requires_accepted_identity_and_selected_header_visibility ... ok
+test allocation_drag::tests::toolbar_identity_allows_exact_incoming_placement_at_old_label_overlap ... ok
+test allocation_drag::tests::uniform_folded_grandchild_and_unplaced_scope_moves_exactly_q_and_all_l_oa_sa ... ok
+test allocation_drag::tests::uniform_role_only_and_mixed_direct_role_composites_same_target_do_not_allocate ... ok
+test allocation_drag::tests::uniformly_unassigned_composite_creates_only_stable_leaf_allocations_including_unplaced ... ok
+test allocation_drag::tests::unrequested_view_option_cleanup_is_not_whitelisted ... ok
+test allocation_drag::tests::unresolved_role_leaf_can_arrange_or_accept_explicit_target_without_guessing ... ok
+test app::allocation_drag::clearance::tests::corner_order_follows_boundary_crossing_and_is_deterministic ... ok
+test app::allocation_drag::clearance::tests::descendant_footprint_controls_clearance_without_mutating_projects ... ok
+test app::allocation_drag::clearance::tests::each_outgoing_edge_clears_the_source_and_passes_ordinary_placement ... ok
+test app::allocation_drag::clearance::tests::independent_selected_roots_keep_one_rigid_group_translation ... ok
+test app::allocation_drag::clearance::tests::no_crossing_no_overlap_no_source_and_nonfinite_requests_are_empty ... ok
+test app::allocation_drag::clearance::tests::source_shrink_uses_candidate_enclosure_not_frozen_target ... ok
+test app::allocation_drag::tests::actual_canvas_origin_change_cancels_held_work_before_any_legacy_release ... ok
+test app::allocation_drag::tests::arrange_is_one_gesture_and_snapped_noop_preserves_redo_and_source ... ok
+test app::allocation_drag::tests::candidate_semantics_are_cached_per_destination_with_stable_ids_and_own_index ... ok
+test app::allocation_drag::tests::destination_identity_does_not_describe_blocked_or_outside_viewport_as_unallocation ... ok
+test app::allocation_drag::tests::frozen_collapsed_target_uses_only_visible_header_and_port_edge_controls_occlude ... ok
+test app::allocation_drag::tests::frozen_targets_use_half_open_semantic_priority_and_refuse_incomparable_overlap ... ok
+test app::allocation_drag::tests::full_tree::actual_app_tree_dirty_description_retains_focus_and_middle_caret_for_next_key ... ok
+test app::allocation_drag::tests::full_tree::actual_app_tree_dirty_name_retains_focus_and_middle_caret_for_next_key ... ok
+test app::allocation_drag::tests::full_tree::actual_app_tree_exact_incoming_drag_keeps_destination_visible_and_canvas_stable ... ok
+test app::allocation_drag::tests::full_tree::actual_keyboard_arrange_shortcut_consumes_once_escape_cancels_and_dirty_owner_refuses ... ok
+test app::allocation_drag::tests::full_tree::actual_rendered_canvas_pixels_do_not_change_when_toolbar_feedback_text_changes ... ok
+test app::allocation_drag::tests::full_tree::actual_toolbar_hover_inspects_last_full_name_without_authorizing_an_outside_drop ... ok
+test app::allocation_drag::tests::full_tree::actual_tree_outgoing_boundary_motion_preview_release_and_cancel ... ok
+test app::allocation_drag::tests::full_tree::control_focus::dirty_selected_pin_outer_ring_keeps_real_name_focus_and_caret ... ok
+test app::allocation_drag::tests::group::allocation_bare_moves_cannot_bypass_armed_active_or_retired_lifetime ... ok
+test app::allocation_drag::tests::group::completed_text_apply_rejects_old_allocation_packets_without_retiring_a_new_drag ... ok
+test app::allocation_drag::tests::group::connection_lifetime::captured_connection_after_cancel_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::connection_lifetime::captured_connection_context_mismatches_preserve_the_current_session ... ok
+test app::allocation_drag::tests::group::connection_lifetime::captured_connection_current_restart_and_pair_commit_after_tool_boundary ... ok
+test app::allocation_drag::tests::group::group_arrange_work_and_performer_anchors_preserve_every_responsibility ... ok
+test app::allocation_drag::tests::group::group_assignment_split_rebuild_preserves_primary_and_commits_one_complete_candidate ... ok
+test app::allocation_drag::tests::group::group_out_and_back_assigns_at_zero_delta_then_true_noop_preserves_redo ... ok
+test app::allocation_drag::tests::group::group_selection_aba_and_old_press_cannot_retire_a_new_token ... ok
+test app::allocation_drag::tests::group::group_source_refusal_retains_primary_source_and_both_history_paths ... ok
+test app::allocation_drag::tests::group::idle_group_press_rejects_selection_generation_aba_with_unchanged_other_stamps ... ok
+test app::allocation_drag::tests::group::ordinary_off_grid_performer_out_and_back_is_noop_with_redo ... ok
+test app::allocation_drag::tests::group::route_lifetime::captured_route_context_fields_independently_reject_before_retirement ... ok
+test app::allocation_drag::tests::group::route_lifetime::current_route_commits_without_session_preserve_exact_route_history ... ok
+test app::allocation_drag::tests::group::route_lifetime::same_context_route_attachment_after_selection_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::route_lifetime::same_context_route_commit_after_selection_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::route_lifetime::stale_route_attachment_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::route_lifetime::stale_route_commit_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::unsupported_group_click_collapses_but_threshold_crossing_never_becomes_click ... ok
+test app::allocation_drag::tests::modal_roundtrip_equal_fit_undo_resize_and_focus_retire_press_before_replay ... ok
+test app::allocation_drag::tests::mounted_clean_stationary_selects_exact_work_without_revision_or_legacy_apply ... ok
+test app::allocation_drag::tests::mounted_dirty_port_press_cannot_fall_through_to_applying_port_selection ... ok
+test app::allocation_drag::tests::mounted_dirty_property_press_does_not_select_apply_or_destroy_draft ... ok
+test app::allocation_drag::tests::mounted_oa_sa_ordered_incoming_between_outgoing_are_exact_single_history_steps ... ok
+test app::allocation_drag::tests::mounted_role_only_outgoing_refusal_retains_placement_and_same_performer_creates_no_allocation ... ok
+test app::allocation_drag::tests::mounted_uniform_parent_moves_hidden_placements_and_assigns_only_leaves ... ok
+test app::allocation_drag::tests::navigation_union::old_chooser_envelopes_preserve_a_current_canvas_gesture ... ok
+test app::allocation_drag::tests::navigation_union::stale_gesture_packets_preserve_navigation_and_a_new_live_cancel_still_works ... ok
+test app::allocation_drag::tests::oa_sa_clipped_selected_header_refuses_preview_release_and_retries_without_partial_source_or_history ... ok
+test app::allocation_drag::tests::oa_sa_toolbar_identity_accepts_exact_receiver_and_collapsed_header_drag ... ok
+test app::allocation_drag::tests::outgoing_boundary_drop_clears_source_without_changing_other_placements ... ok
+test app::allocation_drag::tests::outside_release_is_cancel_and_does_not_remove_an_assignment ... ok
+test app::allocation_drag::tests::pending_behavior_draft_refuses_actual_work_press_and_equal_document_replacement_retires_packet ... ok
+test app::allocation_drag::tests::refused_motion_retains_last_scene_but_release_never_commits_it ... ok
+test app::allocation_drag::tests::release_uses_ordered_native_position_before_later_motion_in_same_batch ... ok
+test app::allocation_drag::tests::same_snapped_position_on_opposite_shared_border_rebuilds_semantics_even_if_layout_refuses ... ok
+test app::allocation_drag::tests::source_and_modal_admission_reject_prebuilt_clean_press_without_selecting ... ok
+test app::allocation_drag::tests::source_refusal_is_atomic_and_a_new_gesture_can_retry_against_live_revision ... ok
+test app::allocation_drag::tests::stale_packets_do_not_cancel_a_newer_token_and_each_release_is_consumed_once ... ok
+test app::allocation_drag::tests::toolbar_destination_names_transformed_target_whose_header_is_clipped ... ok
+test app::allocation_drag::tests::toolbar_status_leaves_transformed_top_edge_work_header_readable ... ok
+
+test result: ok. 121 passed; 0 failed; 0 ignored; 0 measured; 1424 filtered out; finished in 35.33s
+

harness/experiments/drag-out-20260925/tests-04.log

@@ -0,0 +1,131 @@
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `test` profile [unoptimized] target(s) in 6m 05s
+     Running unittests src\main.rs (C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\arcadia_studio-c5b42126ba36cd38.exe)
+
+running 123 tests
+test allocation_drag::outgoing_header_retains_a_grab_region_without_requiring_full_camera_containment ... ok
+test allocation_drag::tests::allocation_artifact_and_manual_trace_cascades_are_named_and_refused ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_detects_hidden_moved_child_and_stationary_enclosure_growth ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_distributed_oa_sa_exact_scope_routes_source_history_and_anchor ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_noop_stale_tamper_target_and_all_selected_headers ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_performer_closure_does_not_acquire_incidental_semantic_root ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_preserves_existing_overlap_but_refuses_its_growth ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_preserves_roles_and_does_not_invent_unplaced_descendants ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_preserves_unrelated_folded_interior_diagnostic_boundary ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_simultaneous_roots_may_enter_each_others_vacated_bounds ... ok
+test allocation_drag::tests::arrange_tests::explicit_arrange_validates_all_original_members_before_normalizing ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_checks_original_identity_and_visibility_before_normalization ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_distributed_parent_refuses_but_its_independent_leaves_can_reassign ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_finish_rejects_stale_project_and_each_tampered_result ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_normalizes_parent_child_and_assigns_unplaced_leaf_once ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_requires_non_anchor_selected_header_inside_viewport ... ok
+test allocation_drag::tests::assignment_boundary_tests::group_assignment_unresolved_oa_role_leaf_accepts_explicit_target_but_not_outside ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_accumulates_stable_ids_and_aliases_without_partial_reuse ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_collateral_surviving_constraint_refuses_whole_semantic_candidate ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_deletes_only_own_routes_across_views_and_keeps_internal_flow ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_independent_performers_preserves_already_correct_provenance ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_source_failure_preserves_existing_history_and_retry_ids ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_unfolds_only_changed_destination_and_refuses_newly_exposed_overlap ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_uses_vacated_space_and_one_complete_route_owner_map ... ok
+test allocation_drag::tests::assignment_tests::group_assignment_zero_delta_changes_semantics_once_and_then_is_noop ... ok
+test allocation_drag::tests::cache_plan_uses_candidate_index_and_same_pixel_different_target_changes_preview ... ok
+test allocation_drag::tests::collapsed_target_unfold_is_explicit_and_no_other_fold_changes ... ok
+test allocation_drag::tests::direct_exit_revealing_another_role_performer_has_truthful_refusal ... ok
+test allocation_drag::tests::explicit_different_performer_retains_advisory_role_warning ... ok
+test allocation_drag::tests::folded_subtree_cannot_hide_new_collision ... ok
+test allocation_drag::tests::geometry_refuses_new_overlap_bounds_and_invisible_headers_and_preserves_existing_overlap ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_detects_moved_folded_child_collision ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_detects_stationary_enclosure_growth_collision ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_distributed_root_and_performer_can_translate_rigidly ... ok
+test allocation_drag::tests::group_arrange_experiment::mixed_arrange_experiment_unrelated_folded_interiors_are_outside_diagnostic_domain ... ok
+test allocation_drag::tests::malformed_scope_wrong_projection_duplicate_placement_and_stable_id_collision_refuse ... ok
+test allocation_drag::tests::mixed_p_x_y_refuses_semantic_and_arrange_instead_of_stretching_destination ... ok
+test allocation_drag::tests::oa_communication_incompleteness_remains_advisory_without_collateral_loss ... ok
+test allocation_drag::tests::oa_sa_incoming_between_outgoing_preserve_identity_source_history_and_other_views ... ok
+test allocation_drag::tests::oa_sa_one_leaf_move_refuses_when_ancestor_regrouping_introduces_unrelated_overlap ... ok
+test allocation_drag::tests::oa_sa_one_leaf_reassignment_and_outward_move_regroup_ancestors_without_moving_sibling ... ok
+test allocation_drag::tests::oa_sa_populated_collapsed_target_accepts_room_and_refuses_collision_without_relocating_contents ... ok
+test allocation_drag::tests::oa_sa_state_owned_action_and_availability_reject_reassignment_atomically ... ok
+test allocation_drag::tests::oa_sa_unfolding_prior_hidden_overlap_refuses_even_when_insertion_does_not_collide ... ok
+test allocation_drag::tests::own_deleted_allocation_routes_may_disappear_in_every_diagram_only ... ok
+test allocation_drag::tests::role_only_same_effective_performer_is_semantic_noop_and_outgoing_refuses ... ok
+test allocation_drag::tests::sa_port_and_deferred_exchange_allocation_cascade_refuses_and_retarget_is_invalid ... ok
+test allocation_drag::tests::same_performer_readability_preserves_snapped_noop_and_allocation_identity ... ok
+test allocation_drag::tests::scope_detects_first_child_allocation_and_role_transfer_and_finish_rejects_live_edits ... ok
+test allocation_drag::tests::selected_header_visibility_allows_viewport_edge_but_refuses_clipping ... ok
+test allocation_drag::tests::snapped_noop_returns_no_command_and_keeps_source_revision_and_redo ... ok
+test allocation_drag::tests::source_budget_refusal_keeps_project_bundle_history_and_retry_identity_exact ... ok
+test allocation_drag::tests::surviving_constraint_mutation_is_refused_even_when_core_candidate_is_valid ... ok
+test allocation_drag::tests::target_presentation_requires_accepted_identity_and_selected_header_visibility ... ok
+test allocation_drag::tests::toolbar_identity_allows_exact_incoming_placement_at_old_label_overlap ... ok
+test allocation_drag::tests::uniform_folded_grandchild_and_unplaced_scope_moves_exactly_q_and_all_l_oa_sa ... ok
+test allocation_drag::tests::uniform_role_only_and_mixed_direct_role_composites_same_target_do_not_allocate ... ok
+test allocation_drag::tests::uniformly_unassigned_composite_creates_only_stable_leaf_allocations_including_unplaced ... ok
+test allocation_drag::tests::unrequested_view_option_cleanup_is_not_whitelisted ... ok
+test allocation_drag::tests::unresolved_role_leaf_can_arrange_or_accept_explicit_target_without_guessing ... ok
+test app::allocation_drag::clearance::tests::corner_order_follows_boundary_crossing_and_is_deterministic ... ok
+test app::allocation_drag::clearance::tests::descendant_footprint_controls_clearance_without_mutating_projects ... ok
+test app::allocation_drag::clearance::tests::each_outgoing_edge_clears_the_source_and_passes_ordinary_placement ... ok
+test app::allocation_drag::clearance::tests::independent_selected_roots_keep_one_rigid_group_translation ... ok
+test app::allocation_drag::clearance::tests::no_crossing_no_overlap_no_source_and_nonfinite_requests_are_empty ... ok
+test app::allocation_drag::clearance::tests::source_shrink_uses_candidate_enclosure_not_frozen_target ... ok
+test app::allocation_drag::tests::actual_canvas_origin_change_cancels_held_work_before_any_legacy_release ... ok
+test app::allocation_drag::tests::arrange_is_one_gesture_and_snapped_noop_preserves_redo_and_source ... ok
+test app::allocation_drag::tests::candidate_semantics_are_cached_per_destination_with_stable_ids_and_own_index ... ok
+test app::allocation_drag::tests::destination_identity_does_not_describe_blocked_or_outside_viewport_as_unallocation ... ok
+test app::allocation_drag::tests::frozen_collapsed_target_uses_only_visible_header_and_port_edge_controls_occlude ... ok
+test app::allocation_drag::tests::frozen_targets_use_half_open_semantic_priority_and_refuse_incomparable_overlap ... ok
+test app::allocation_drag::tests::full_tree::actual_app_tree_dirty_description_retains_focus_and_middle_caret_for_next_key ... ok
+test app::allocation_drag::tests::full_tree::actual_app_tree_dirty_name_retains_focus_and_middle_caret_for_next_key ... ok
+test app::allocation_drag::tests::full_tree::actual_app_tree_exact_incoming_drag_keeps_destination_visible_and_canvas_stable ... ok
+test app::allocation_drag::tests::full_tree::actual_keyboard_arrange_shortcut_consumes_once_escape_cancels_and_dirty_owner_refuses ... ok
+test app::allocation_drag::tests::full_tree::actual_rendered_canvas_pixels_do_not_change_when_toolbar_feedback_text_changes ... ok
+test app::allocation_drag::tests::full_tree::actual_toolbar_hover_inspects_last_full_name_without_authorizing_an_outside_drop ... ok
+test app::allocation_drag::tests::full_tree::actual_tree_outgoing_boundary_motion_preview_release_and_cancel ... ok
+test app::allocation_drag::tests::full_tree::control_focus::dirty_selected_pin_outer_ring_keeps_real_name_focus_and_caret ... ok
+test app::allocation_drag::tests::group::allocation_bare_moves_cannot_bypass_armed_active_or_retired_lifetime ... ok
+test app::allocation_drag::tests::group::completed_text_apply_rejects_old_allocation_packets_without_retiring_a_new_drag ... ok
+test app::allocation_drag::tests::group::connection_lifetime::captured_connection_after_cancel_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::connection_lifetime::captured_connection_context_mismatches_preserve_the_current_session ... ok
+test app::allocation_drag::tests::group::connection_lifetime::captured_connection_current_restart_and_pair_commit_after_tool_boundary ... ok
+test app::allocation_drag::tests::group::group_arrange_work_and_performer_anchors_preserve_every_responsibility ... ok
+test app::allocation_drag::tests::group::group_assignment_split_rebuild_preserves_primary_and_commits_one_complete_candidate ... ok
+test app::allocation_drag::tests::group::group_out_and_back_assigns_at_zero_delta_then_true_noop_preserves_redo ... ok
+test app::allocation_drag::tests::group::group_selection_aba_and_old_press_cannot_retire_a_new_token ... ok
+test app::allocation_drag::tests::group::group_source_refusal_retains_primary_source_and_both_history_paths ... ok
+test app::allocation_drag::tests::group::idle_group_press_rejects_selection_generation_aba_with_unchanged_other_stamps ... ok
+test app::allocation_drag::tests::group::ordinary_off_grid_performer_out_and_back_is_noop_with_redo ... ok
+test app::allocation_drag::tests::group::route_lifetime::captured_route_context_fields_independently_reject_before_retirement ... ok
+test app::allocation_drag::tests::group::route_lifetime::current_route_commits_without_session_preserve_exact_route_history ... ok
+test app::allocation_drag::tests::group::route_lifetime::same_context_route_attachment_after_selection_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::route_lifetime::same_context_route_commit_after_selection_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::route_lifetime::stale_route_attachment_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::route_lifetime::stale_route_commit_preserves_arrange_arm_and_live_group ... ok
+test app::allocation_drag::tests::group::unsupported_group_click_collapses_but_threshold_crossing_never_becomes_click ... ok
+test app::allocation_drag::tests::modal_roundtrip_equal_fit_undo_resize_and_focus_retire_press_before_replay ... ok
+test app::allocation_drag::tests::mounted_clean_stationary_selects_exact_work_without_revision_or_legacy_apply ... ok
+test app::allocation_drag::tests::mounted_dirty_port_press_cannot_fall_through_to_applying_port_selection ... ok
+test app::allocation_drag::tests::mounted_dirty_property_press_does_not_select_apply_or_destroy_draft ... ok
+test app::allocation_drag::tests::mounted_oa_sa_ordered_incoming_between_outgoing_are_exact_single_history_steps ... ok
+test app::allocation_drag::tests::mounted_role_only_outgoing_refusal_retains_placement_and_same_performer_creates_no_allocation ... ok
+test app::allocation_drag::tests::mounted_uniform_parent_moves_hidden_placements_and_assigns_only_leaves ... ok
+test app::allocation_drag::tests::navigation_union::old_chooser_envelopes_preserve_a_current_canvas_gesture ... ok
+test app::allocation_drag::tests::navigation_union::stale_gesture_packets_preserve_navigation_and_a_new_live_cancel_still_works ... ok
+test app::allocation_drag::tests::oa_sa_clipped_selected_header_refuses_preview_release_and_retries_without_partial_source_or_history ... ok
+test app::allocation_drag::tests::oa_sa_toolbar_identity_accepts_exact_receiver_and_collapsed_header_drag ... ok
+test app::allocation_drag::tests::outgoing_boundary_drop_clears_source_without_changing_other_placements ... ok
+test app::allocation_drag::tests::outgoing_clearance_collision_refuses_release_without_source_or_history_mutation ... ok
+test app::allocation_drag::tests::outgoing_clearance_preserves_source_enclosure_and_allocated_sibling ... ok
+test app::allocation_drag::tests::outside_release_is_cancel_and_does_not_remove_an_assignment ... ok
+test app::allocation_drag::tests::pending_behavior_draft_refuses_actual_work_press_and_equal_document_replacement_retires_packet ... ok
+test app::allocation_drag::tests::refused_motion_retains_last_scene_but_release_never_commits_it ... ok
+test app::allocation_drag::tests::release_uses_ordered_native_position_before_later_motion_in_same_batch ... ok
+test app::allocation_drag::tests::same_snapped_position_on_opposite_shared_border_rebuilds_semantics_even_if_layout_refuses ... ok
+test app::allocation_drag::tests::source_and_modal_admission_reject_prebuilt_clean_press_without_selecting ... ok
+test app::allocation_drag::tests::source_refusal_is_atomic_and_a_new_gesture_can_retry_against_live_revision ... ok
+test app::allocation_drag::tests::stale_packets_do_not_cancel_a_newer_token_and_each_release_is_consumed_once ... ok
+test app::allocation_drag::tests::toolbar_destination_names_transformed_target_whose_header_is_clipped ... ok
+test app::allocation_drag::tests::toolbar_status_leaves_transformed_top_edge_work_header_readable ... ok
+
+test result: ok. 123 passed; 0 failed; 0 ignored; 0 measured; 1424 filtered out; finished in 54.86s
+

harness/experiments/grid-cache-20260925/.gitattributes

@@ -0,0 +1,2 @@
+*.log -text
+*.rs -text

harness/experiments/grid-cache-20260925/COLD-PAN.md

@@ -0,0 +1,153 @@
+# Cold construction and pan alternatives
+
+Follow-up to [the stationary-camera cache](README.md), for issue 44. Application
+source remains `336720559bcec511949caa8a42bee8a55c3822da`, with evidence checkpoint
+`2ca84676ee4dc30846208881a27d90a901482085`. These standalone experiments change no
+application code, dependencies, event handling or release. Native interaction
+remains paused; no result below establishes native FPS.
+
+## Question and method
+
+The existing cache removes repeated construction at identical camera inputs but
+misses during pan/zoom. Can simpler geometry or renderer-level translation remove
+that cost without changing the grid's appearance? Use the same unoptimized Iced
+0.14 WGPU dependencies and Windows environment recorded in `context.json`.
+Compile the new drivers with the same `rustc`/extern/linker arguments described
+in README, replacing the driver filename and output executable. No desktop window
+is created and no input is sent. Run `cold_grid_probe` with argument `20`; phase
+drivers take no arguments.
+
+The cold driver compares original circles, one reusable origin circle transformed
+for each fill, one path per column, and direct 1.15-unit squares. Every candidate
+also constructs one origin-circle template; this small common overhead is retained.
+Three warmups precede 20 changing-pan samples. Construction ends before geometry
+destruction, rendering and readback. Percentiles use sorted index `ceil((n-1)*p)`.
+Fixed candidate ordering and uncontrolled OS load limit small timing comparisons.
+
+## Cold construction results
+
+`cold_grid_probe.rs` produces `grid-cold-01.log`. Median milliseconds:
+
+| Canvas, zoom | Original | Reused circle | Column batch | Square |
+| --- | ---: | ---: | ---: | ---: |
+| 1900x660, 1.0 | 61.0564 | 55.3975 | 54.3594 | 3.5527 |
+| 1900x660, 0.5 | 215.8919 | 162.3073 | 158.5968 | 7.5699 |
+| 1440x900, 1.0 | 60.1683 | 43.3860 | 60.8198 | 2.0340 |
+| 1440x900, 0.5 | 165.2049 | 133.3420 | 143.1489 | 6.8178 |
+
+Both circle alternatives exactly match original pixels in all 12 sampled cases
+(four integer canvas/zoom pairs, three pan offsets, scale 1). This does not prove
+equivalence at fractional zoom, other DPI or other camera inputs. Squares match
+eight of those cases but differ at the third pan offset in each canvas/zoom pair:
+4,266–13,184 changed pixels, maximum channel difference 7. Their different shape
+and area are an explicit appearance change, not a pixel-preserving optimization.
+
+Reusing circles and column batches leave substantial cold cost; the experiment
+does not justify adding them to production as the solution to low FPS. The square
+alternative is much faster in this scope, but is not adopted without evaluating
+its appearance and the actual interaction result. The previous all-grid single
+path experiment remains rejected for its much higher construction cost.
+
+## Source explanation and independent review
+
+A fresh read-only critic checked the probes and actual local Iced source. Each
+`Path::circle` allocates/builds a path and converts its arc into quadratic segments.
+Each WGPU `Frame::fill` allocates a boxed geometry builder and invokes Lyon fill
+tessellation. Same-color fills already share a solid mesh buffer: this is not
+one GPU draw call per dot. Frame translation transforms paths before tessellation,
+so path reuse alone does not reuse triangles.
+
+Renderer-level `with_translation` can reuse cached triangles. Stock Canvas cannot
+attach a separate transform to each returned geometry; application adoption would
+need a small background widget or wrapper, with layout, clipping, lifecycle and
+interaction checks. Scaling the grid to handle zoom is unsuitable because the
+dot radius must remain fixed in screen units.
+
+The critic also identified two important controls. Original opaque background
+geometry must not silently become screenshot-clear color: MSAA/alpha composition
+can change quantized pixels. Also, `iced_wgpu::triangle::Storage::prepare` rewrites
+cached mesh data when its transform changes. Construction/command-recording time
+therefore excludes real preparation/upload costs. The later probe measures a
+rendering/readback path separately; neither timer represents native presentation.
+
+Primary sources: Iced 0.14 `iced_graphics/src/geometry/path{,/builder}.rs`,
+`iced_wgpu/src/{geometry,triangle}.rs`, `iced_core/src/renderer.rs`, and
+`iced_widget/src/canvas.rs`. The reviewer changed no files and did not execute the
+probes; execution and interpretation remain the parent's responsibility.
+
+## Renderer-translated phase cache
+
+`phase_grid_probe_v1.rs` / `grid-phase-01.log` cache zero-phase circles once for
+each size/spacing pair, translate by `pan.rem_euclid(step)`, and externally clip
+to the original viewport. The original nonnegative row/column indices and fixed
+screen-space radius are retained. Cache clip bounds include the radius margins.
+This first prototype uses screenshot clear color instead of opaque background
+geometry; its widespread one-level pixel differences are not accepted as parity.
+Its compiler emitted one duplicate Renderer-import warning, retained in the
+original driver. Later drivers remove that import and compile with `-D warnings`.
+
+`phase_grid_opaque_probe.rs` / `grid-phase-opaque-01.log` add an oversized opaque
+background to the same cached geometry as the circles. Its bounds extend from
+`(-step,-step)` to `(width+2*step,height+2*step)`, covering the viewport at every
+positive remainder without adding extra dot rows or columns. This directly
+compares against the unchanged legacy painter. A proposed separate-background
+control was not executed; no result is claimed for it.
+
+Of 75 comparisons (five size/zoom pairs, five offsets, three DPI scales), 73 are
+byte-exact. All 60 cases at integer canvas sizes and spacing 14 or 24 are exact.
+At 301.5x211.25, zoom 0.73, pan (-13.25,9.75), scale 1 changes 12 pixels by at
+most one channel level; scale 2 changes one pixel by at most six levels. These
+are failures of exact parity and are preserved, not hidden behind a tolerance.
+
+The targeted `phase_grid_diagnostic.rs` / `grid-phase-diagnostic-01.log` locates
+all 12 scale-1 differences at the rightmost physical column x=301. The scale-2
+single-pixel difference does not recur. That diagnostic skips earlier large
+cases and their rendering/timing sequence: it does not exonerate the earlier
+failure or establish that every residual difference is at an edge.
+
+The replay driver's first compilation failed with E0689 because the new control's
+`Vector::new(-13.25,9.75)` left its numeric type ambiguous before `rem_euclid`.
+An explicit `Vector<f32>` annotation corrects the experiment harness. No probe
+executed during that failed attempt; no application source changed.
+
+`phase_grid_replay.rs` preserves the full opaque probe's rendering/timing sequence
+and adds coordinate diagnostics without extra renders until that sequence ends.
+`grid-phase-replay-01.log` reproduces both failures: the 12 right-edge pixels and
+one **interior** pixel at physical (149,263), where legacy RGBA is
+`[240,243,246,255]` and cached RGBA is `[246,248,251,255]`. The latter cannot be
+dismissed as viewport-edge rounding. Afterwards, all 12 same-renderer repeat
+controls (three repetitions of old/old and cached/cached at two scales) are
+byte-exact; the control cache builds once. This finite control does not establish
+universal determinism, but supports investigating differing geometry coverage
+instead of treating the reproduced pixel as random readback noise.
+
+Cold construction plus command recording takes 68.42–173.72ms median for the four
+large viewports; cached translation takes 0.0008–0.0011ms. Each per-size/spacing
+cache builds exactly once through all pan comparisons and measurements. Zoom
+and resize through a single retained cache are not tested by these drivers.
+The labels containing `submit` mean renderer command recording, not GPU submission.
+
+Two selected cases include construction, recording, backend preparation and GPU
+readback in a separate timer (two warmups, eight samples, sorted-index median):
+
+| Canvas, zoom | Original p50 ms | Phase cache p50 ms |
+| --- | ---: | ---: |
+| 1900x660, 1.0 | 259.9265 | 212.6536 |
+| 1440x900, 0.5 | 337.2560 | 170.3780 |
+
+These support a benefit within the headless path, but retain significant renderer
+and readback cost and variable outliers. They are not native frame times. Sample
+size, sequential ordering and uncontrolled machine load prohibit a precise
+general speedup claim. All driver/log hashes and execution mapping are in
+`cold-pan-context.json`.
+
+The phase candidate removes the measured pan tessellation cost, but does not
+meet exact visual preservation. Do not adopt it as an invisible optimization.
+The small circle rewrites leave the main cost and squares change appearance.
+Further work should investigate the reproduced interior coverage difference or
+compare optimized dependency/build profiles before adding a custom widget.
+Any adopted rendering candidate must then verify a real mounted scene at a
+nonzero widget origin, foreground ordering, viewport clipping, pan/zoom/resize
+cache lifecycle and unchanged event behavior. Native interaction/FPS verification
+remains a separate required gate. No application implementation is changed by
+these experiments.

harness/experiments/grid-cache-20260925/README.md

@@ -0,0 +1,180 @@
+# Architecture background geometry cache
+
+Scope: [issue 44](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/issues/44).
+Production/test candidate: `636093aae67aa48fa1d35e403a205227e81d04de`, based on
+`c0908f101ac376afb8021e60e454e2a176e49d45`. The base includes the separately
+unaccepted outgoing-drag contribution for issue 40. This is a contribution
+experiment and repair, not an integrated release or full FPS acceptance.
+
+## Question and evidence
+
+The [preceding core probe](../architecture-perf-20260925/README.md) measured
+approximately 4.26ms median for preparation/projection/routing in an eight-card
+approximation. It did not reproduce the reported severe slowdown. Source review
+then identified repeated grid construction on every canvas redraw, despite the
+grid's independence from model edits, selection and pointer position.
+
+The standalone headless Iced probe copies the former grid loop: background fill,
+then one radius-0.65 circle per grid point, with the same spacing, pan remainder
+and colors. It measures geometry construction independently from offscreen
+rendering/readback, using the actual compiled development-profile Iced renderer.
+It creates no desktop window and sends no input. Three warmups precede 20 samples
+per phase. The timer includes construction and returning geometry; returned
+geometry destruction occurs afterwards. Sorted index `ceil((n-1)*p)` supplies
+reported percentiles. Renderer startup is outside the timed phases.
+
+`grid-performance-01.log`, produced by `grid_render_probe_v1.rs`, records:
+
+| Canvas, zoom | Dots | Fresh geometry p50 ms | Cache retrieval p50 ms |
+| --- | ---: | ---: | ---: |
+| 1900x660, 1.0 | 2,240 | 67.8095 | 0.0001 |
+| 1900x660, 0.5 | 6,528 | 192.5581 | 0.0001 |
+| 1440x900, 1.0 | 2,318 | 66.2206 | 0.0002 |
+| 1440x900, 0.5 | 6,695 | 219.1771 | 0.0002 |
+
+Cold and warm cached grid pixels equal the uncached result byte for byte in all
+four cases. Cache misses remain comparable to fresh construction; caching does
+not improve continuously changing camera inputs. Offscreen screenshot/readback
+cost remains substantial and variable. It must not be converted to native FPS.
+
+## Candidate comparison and chosen change
+
+1. Rebuild each circle every draw: exact current appearance, but the measured
+   repeated CPU cost alone is large in this development build.
+2. Batch circles into one path: keeps the same pixels in this experiment but is
+   materially slower. `grid_render_probe.rs` and `grid-performance-02.log` retain
+   this rejected candidate. Its construction medians range from 274.66ms to
+   1,225.53ms, versus 63.82–178.24ms for the original loop in the same run.
+3. Cache background geometry while camera and size stay identical: selected.
+   It preserves the original painter and removes its repeated construction from
+   stationary-camera interactions. It adds a small local cache, not a second
+   geometry implementation or a model-level cache.
+
+`diagram/grid.rs` owns an Iced geometry cache and an exact raw `(zoom, pan)` key.
+Iced's cache checks exact frame size. Camera changes explicitly clear it. The
+colors and dot radius remain compile-time constants; future runtime styling
+must invalidate this cache too. The conservative key rebuilds after a whole
+grid-period pan and after zoom changes within the minimum-spacing clamp. No
+fractional coordinates are rounded or tolerance-compared.
+
+Drawing order becomes `[cached background and dots, live diagram, warnings]`.
+The opaque background is in the first geometry, so it cannot cover the dots.
+Existing pan/zoom transforms still apply only to the live model geometry.
+The cache lives in the retained canvas State; model revisions and selections
+do not invalidate it. Existing focus/suspension tree resets cause a safe cold
+rebuild. No routing, model semantics, hit testing or gesture admission changes.
+
+`production_grid_probe.rs` imports the actual candidate cache. Its exploratory
+run 03 was performed before the source commit and formatting; the raw log is
+retained as local precommit evidence, not relabeled as a binary from the commit.
+The same source is supplied for reproduction at the identified candidate.
+
+The separately recompiled run 04 imports the committed `636093aa` cache and ran
+after the full desktop test process exited, before Clippy/build compilation.
+`grid-performance-04.log` records exact baseline/cached pixels and these medians:
+
+| Canvas, zoom | Fresh geometry ms | Production cache hit ms | Changing-pan rebuild ms |
+| --- | ---: | ---: | ---: |
+| 1900x660, 1.0 | 61.8281 | 0.0002 | 59.2995 |
+| 1900x660, 0.5 | 158.8603 | 0.0002 | 163.4359 |
+| 1440x900, 1.0 | 50.5385 | 0.0002 | 53.5840 |
+| 1440x900, 0.5 | 168.4092 | 0.0002 | 175.2457 |
+
+These results support the same bounded conclusion as the exploratory trials.
+The run record preserves linked-library, driver and log hashes; timing noise
+and screenshot readback remain explicit limitations.
+Run 04 directly compares the production cache's cold pixels; its generic
+cold-and-warm marker refers to the Iced-cache control. Warm production-cache
+pixel parity is established separately by the committed grid tests.
+
+## Verification and boundaries
+
+Three committed headless tests check:
+
+- Cache construction count through 18 exact camera/size changes, including
+  negative/fractional pan, zero-pan zoom changes, the minimum-spacing transition,
+  independent width/height resizing and return to previous dimensions.
+- Exact RGBA equality against an independent copy of the legacy loop and
+  unsplit geometry. The scenes contain opaque cards, crossing edges, text,
+  translucent overdraw, selection handles and a warning overlay. Foreground
+  edits must visibly change pixels while retaining the background cache.
+- The actual `DiagramCanvas` with one retained State: selection and model
+  revision changes must alter rendered pixels without rebuilding the grid;
+  pan and resize must rebuild it. This is drawing/scene-invalidation evidence,
+  not an event-driven native gesture test.
+
+Fresh read-only independent review found no concrete cache-key, lifetime,
+ordering or test-oracle defect. It checked the corresponding Iced 0.14 cache
+and mesh-layer implementations. This review does not establish execution.
+At `636093aa`, `grid-tests-01.log` passes all three targeted tests in 2.97s.
+`grid-desktop-01.log` passes the full desktop suite in 362.14s: 1,543 passed,
+zero failed, seven existing manual/diagnostic tests ignored, none filtered out.
+All 1,550 distinct test names were counted; `context.json` lists the seven
+ignored cases and records raw log hashes. This is desktop regression evidence;
+it does not relabel the ignored checks as passing or establish native FPS.
+The [independent review](independent-review.md) states its exact scope.
+
+The initial strict Clippy run (`grid-clippy-01.log`) failed on two uses of
+`chunks_exact(4)` in the new test helper. Test-only successor
+`336720559bcec511949caa8a42bee8a55c3822da` uses `as_chunks::<4>()`; it leaves
+production inputs unchanged. The original full-suite result remains associated
+with `636093aa`, not relabeled as execution at the successor.
+At the successor, strict all-target Clippy passes in 2m01s
+(`grid-clippy-02.log`) and the three affected grid tests pass again in 4.13s
+(`grid-tests-02.log`). No warning suppression or test exclusion was introduced.
+
+The normal Windows GUI build at `33672055` also passes in 2m15s
+(`desktop-build-02.log`). The executable and required `libunwind.dll` are staged
+locally for later native verification, but this candidate has not been launched.
+The executable SHA-256 is
+`78548e93d4b57130ed507ed0f29eddbdbafb4721b38b0cd6d06101d5324114dd`;
+`context.json` records both staged file hashes. Staging is not publication of a
+new runnable release or native acceptance.
+
+Remaining limits: the user's exact saved scene is unavailable; these results do
+not establish end-to-end native FPS. Continuous pan/zoom still pays the cold
+construction cost. Native desktop verification remains paused after user Escape.
+Neither issue 40 nor issue 44 is closed by this headless experiment. Linux/WSL
+remains deferred by the user. No published release has been replaced.
+
+## Environment and reproduction
+
+The subsequent [cold-construction and pan experiments](COLD-PAN.md) compare
+additional approaches, including a renderer-translated cache. They preserve
+their own pixel differences, timing limits and adoption gates; they do not
+change the production implementation verified above.
+
+Windows 10.0.26200, Rust 1.98.1, x86_64-pc-windows-gnullvm, development profile
+with debug information disabled. The exposed CPU is Intel Core i7-10870H with
+4 cores/threads; Windows reports VMware SVGA 3D, driver 9.17.11.4. The headless
+renderer identifies itself as `wgpu`; the probe does not identify its selected
+adapter or equate it with the desktop presenter's adapter. Other OS workloads
+were not controlled, so measured outliers are preserved.
+
+At the candidate source, the normal gates are:
+
+```powershell
+cargo test --locked --offline -p oa-desktop diagram::grid::tests -- --test-threads=1
+cargo test --locked --offline -p oa-desktop -- --test-threads=1
+cargo clippy --locked --offline -p oa-desktop --all-targets -- -D warnings
+cargo build --locked --offline -p oa-desktop --bin arcadia-studio
+```
+
+For the standalone probes, first build the desktop dependencies in that profile.
+Compile with `rustc --edition=2024 -C opt-level=0`, supplying `--extern iced=...`
+and `--extern tokio=...` for the matching rlibs, plus `-L dependency=...` for
+their directory. On this toolchain the link also needs `-C linker=clang.exe`
+and `-L native=.../windows_x86_64_gnullvm-0.52.6/lib`. The original inputs were
+`libiced-594f7d417d69ed72.rlib` and `libtokio-5e0ca96735e3073a.rlib` from
+`target/debug/deps`. Run the resulting executable with argument `20`.
+The production probe's relative module path requires compiling it at its
+versioned location. Keep linker and runtime DLLs on PATH.
+
+The first experimental compile failed because the configured futures crate
+lacked its executor feature and an inherent screenshot method shadowed the
+Headless trait method. Using the existing Tokio runtime and explicitly calling
+`Headless::screenshot` corrected those driver errors. A second link failed for
+the Windows import library search path; `grid-build-02.log` retains that failure.
+Adding the native library path allowed subsequent probes to run. These failures
+occurred in the experimental driver, before execution; they are not passing
+application checks.

harness/experiments/grid-cache-20260925/cold-pan-context.json

@@ -0,0 +1,51 @@
+{
+  "application_source": "336720559bcec511949caa8a42bee8a55c3822da",
+  "base_evidence": "2ca84676ee4dc30846208881a27d90a901482085",
+  "production_changes": false,
+  "environment": "Same unoptimized Windows Iced/Tokio artifacts as context.json",
+  "logs": [
+    {
+      "driver": "cold_grid_probe.rs",
+      "exit_code": 0,
+      "log": "grid-cold-01.log"
+    },
+    {
+      "driver": "phase_grid_probe_v1.rs",
+      "exit_code": 0,
+      "compile_warning": "Unused duplicate Renderer trait import; retained in original driver",
+      "log": "grid-phase-01.log"
+    },
+    {
+      "driver": "phase_grid_opaque_probe.rs",
+      "exit_code": 0,
+      "compile_warnings_denied": true,
+      "log": "grid-phase-opaque-01.log"
+    },
+    {
+      "driver": "phase_grid_diagnostic.rs",
+      "exit_code": 0,
+      "compile_warnings_denied": true,
+      "log": "grid-phase-diagnostic-01.log"
+    },
+    {
+      "driver": "phase_grid_replay.rs",
+      "log": "grid-phase-replay-01.log",
+      "exit_code": 0,
+      "compile_warnings_denied": true,
+      "initial_compile": "E0689 ambiguous Vector scalar before rem_euclid, fixed with Vector<f32>; no execution on failed attempt"
+    }
+  ],
+  "sha256": {
+    "cold_grid_probe.rs": "a4cc6543229ae4901d54061823a3b05ec6fe3b988f245df12898e013dbb93323",
+    "phase_grid_probe_v1.rs": "c4293e8bb022fae5bffe67002a6f7c867549f2fa8a865b107f39070655bc57fc",
+    "phase_grid_opaque_probe.rs": "43ac5be462ca31f9d1c49554291e08b60bac9de38face7138eaa850e4dcc0ab9",
+    "phase_grid_diagnostic.rs": "8de3c980ac65eef4fcb32b1b121d14aca35b93c704c5b19a440ad9dc7042248c",
+    "grid-cold-01.log": "ca5cac0be409bafcea2c154d42998cbd622c9e898892574bcd5a2df0c1a70886",
+    "grid-phase-01.log": "e0b2e2a3e24d642e1b6c2b1b418f24c952399758159de051f7c1ba7efbb39c4a",
+    "grid-phase-opaque-01.log": "2716cbeb589f4b23a48575680022231c0b94b56ba9c06ec1adbf9e3e6d07f7cd",
+    "grid-phase-diagnostic-01.log": "1dbb0f745169b88c56a21683dba6797a3dbbe753e8dd742bc9ecc8ca24788886",
+    "phase_grid_replay.rs": "96e62ba5d08f7e26d9705d3f90e3785151597b526293439345b59ed842de4971",
+    "grid-phase-replay-01.log": "040034be1b8eb3d4fc010bbe34c5ded47a953b8295bcf2f9440507d1a149da1f"
+  },
+  "native_fps": "unverified"
+}

harness/experiments/grid-cache-20260925/cold_grid_probe.rs

@@ -0,0 +1,142 @@
+//! Experimental cold-grid candidates; no window or input automation.
+use iced::advanced::{
+    graphics::geometry::Renderer as _,
+    renderer::{Headless, Renderer as _},
+};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Frame, Geometry, Path},
+};
+use std::{hint::black_box, time::Instant};
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+
+#[derive(Debug, Clone, Copy)]
+enum Candidate {
+    Original,
+    Template,
+    Column,
+    Square,
+}
+fn draw(r: &Renderer, size: Size, zoom: f32, pan: Vector, candidate: Candidate) -> Geometry {
+    let mut f = Frame::new(r, size);
+    f.fill_rectangle(Point::ORIGIN, size, BG);
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    let circle = Path::circle(Point::ORIGIN, 0.65);
+    for x in 0..(size.width / step) as i32 + 1 {
+        if matches!(candidate, Candidate::Column) {
+            let p = Path::new(|p| {
+                for y in 0..(size.height / step) as i32 + 1 {
+                    p.circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65);
+                    p.close();
+                }
+            });
+            f.fill(&p, DOT);
+            continue;
+        }
+        for y in 0..(size.height / step) as i32 + 1 {
+            let center = Point::new(ox + x as f32 * step, oy + y as f32 * step);
+            match candidate {
+                Candidate::Original => f.fill(&Path::circle(center, 0.65), DOT),
+                Candidate::Template => f.with_save(|f| {
+                    f.translate(Vector::new(center.x, center.y));
+                    f.fill(&circle, DOT);
+                }),
+                Candidate::Square => f.fill_rectangle(
+                    center - Vector::new(0.575, 0.575),
+                    Size::new(1.15, 1.15),
+                    DOT,
+                ),
+                Candidate::Column => unreachable!(),
+            }
+        }
+    }
+    f.into_geometry()
+}
+fn pixels(r: &mut Renderer, size: Size, g: Geometry) -> Vec<u8> {
+    r.reset(Rectangle::with_size(size));
+    r.draw_geometry(g);
+    Headless::screenshot(r, Size::new(size.width as u32, size.height as u32), 1., BG)
+}
+fn main() {
+    let n = std::env::args()
+        .nth(1)
+        .map(|s| s.parse::<usize>().unwrap())
+        .unwrap_or(20)
+        .max(1);
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut r = rt
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .unwrap();
+    println!(
+        "renderer={} n={n}; construction only, unoptimized linked dependencies; NOT native FPS",
+        r.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+    ] {
+        println!("size={}x{} zoom={zoom}", size.width, size.height);
+        for candidate in [
+            Candidate::Original,
+            Candidate::Template,
+            Candidate::Column,
+            Candidate::Square,
+        ] {
+            for pan in [
+                Vector::new(-13.25, 9.75),
+                Vector::new(0., 0.),
+                Vector::new(6.125, -8.5),
+            ] {
+                let base = draw(&r, size, zoom, pan, Candidate::Original);
+                let base = pixels(&mut r, size, base);
+                let test = draw(&r, size, zoom, pan, candidate);
+                let test = pixels(&mut r, size, test);
+                let changed = base
+                    .chunks_exact(4)
+                    .zip(test.chunks_exact(4))
+                    .filter(|(a, b)| a != b)
+                    .count();
+                let max = base
+                    .iter()
+                    .zip(&test)
+                    .map(|(a, b)| a.abs_diff(*b))
+                    .max()
+                    .unwrap_or(0);
+                println!(
+                    "{candidate:?} pan={},{} changed_pixels={changed} max_channel_delta={max}",
+                    pan.x, pan.y
+                );
+            }
+            let mut ms = Vec::new();
+            for i in 0..n + 3 {
+                let pan = Vector::new(-13.25 + i as f32 * 0.25, 9.75);
+                let now = Instant::now();
+                let g = black_box(draw(&r, size, zoom, pan, candidate));
+                let elapsed = now.elapsed().as_secs_f64() * 1000.;
+                drop(g);
+                if i >= 3 {
+                    ms.push(elapsed);
+                }
+            }
+            ms.sort_by(f64::total_cmp);
+            println!(
+                "{candidate:?} changing_pan n={n} p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+                ms[((n - 1) as f64 * 0.5).ceil() as usize],
+                ms[((n - 1) as f64 * 0.95).ceil() as usize],
+                ms[n - 1]
+            );
+        }
+    }
+}

harness/experiments/grid-cache-20260925/context.json

@@ -0,0 +1,61 @@
+{
+  "source": "636093aae67aa48fa1d35e403a205227e81d04de",
+  "target": "x86_64-pc-windows-gnullvm",
+  "rustc": "1.98.1",
+  "rust_llvm": "22.1.8",
+  "linker_clang": "23.1.1",
+  "profile": "dev/test unoptimized debug=0",
+  "incremental": false,
+  "build_jobs": 1,
+  "full_test_count": 1550,
+  "passed": 1543,
+  "ignored": 7,
+  "failed": 0,
+  "ignored_tests": [
+    "app::source_rename::timing_tests::accepted_release1_prepare_commit_sync_and_confirm_timing",
+    "app::source_rename::timing_tests::layout_timing_tests::accepted_release1_constructor_vs_reuse_through_next_highlight",
+    "app::source_symbols::tests::source_symbols_100_modules_1000_definitions_10000_uses",
+    "behavior::scenario::spacing::controller::timing_tests::saved_spacing_capture_prepare_20_lanes_1000_messages_3_views",
+    "source_annotations::anchor_tests::final_multi_glyph_cluster_anchor_uses_logical_trailing_advance_edge",
+    "source_annotations::anchor_tests::mixed_direction_omitted_separator_has_one_logical_predecessor_anchor",
+    "source_annotations::performance_tests::annotation_projection_cost_distributions"
+  ],
+  "log_sha256": {
+    "grid-tests-01.log": "ed76ce90e9246dfddf1d3a96d6a1b91d0d0719701b1d09ddb639a1277c089612",
+    "grid-desktop-01.log": "2000cf03685d6fde73c3dede90f84153a45c6ad0a5c2886a2bc09dda98ba63c3",
+    "grid-performance-04.log": "c492aba0bbe600fa1c2a7f0ac52e5706d29cb67aca95fa3a31641ff7f90c2412",
+    "grid-clippy-01.log": "2498a3d0be9738b8e43ae588c23d6e48f531fdbfc5f47d2f79c1a2f0f1b5bdc1",
+    "grid-clippy-02.log": "69de93cce0c53f37f3c82eb28a28c1610548b30fec4680f02b9b7b118606040f",
+    "grid-tests-02.log": "54c1d72402310be8b3026886dfda0339aa1a81c76b8165c40c97ea075524bff2",
+    "desktop-build-02.log": "e39d1eaaceb8a5805a486c204d6eca7e1ce2b9b39b232e770ab0ad33cbe0e860"
+  },
+  "native_acceptance": "unverified",
+  "source_clean_after_full_test": true,
+  "timing_run": {
+    "source": "636093aae67aa48fa1d35e403a205227e81d04de",
+    "samples": 20,
+    "warmups": 3,
+    "probe_exe_sha256": "79c2e0b64cfacf24b7ee10d8690969d961753945f45d16a743ea750b9eb049d0",
+    "probe_source_sha256": "e6efe1e510164444912d05a96e49c55d791b7046102013458a5ad94bd474a6cd",
+    "grid_git_blob_sha256": "5e7c54d1b4da2e2c082f8ef011a3755f8808fcd67f1babf3be5448cd94240e6c",
+    "iced_rlib_sha256": "9fec4bea1a5ac7e1ae75d786b76e3dbe97a6f63b30d11b6753f268c2ad9efbc6",
+    "tokio_rlib_sha256": "78587ae94762065914b25065c85d9cb66106b71619ec7b65f5e16cdeb689abb9"
+  },
+  "test_only_successor": {
+    "source": "336720559bcec511949caa8a42bee8a55c3822da",
+    "change": "chunks_exact(4) replaced by as_chunks::<4>() in the pixel test helper",
+    "targeted_passed": 3,
+    "targeted_failed": 0,
+    "targeted_filtered": 1547,
+    "strict_clippy": "passed",
+    "normal_build": "passed"
+  },
+  "staged_candidate": {
+    "source": "336720559bcec511949caa8a42bee8a55c3822da",
+    "launched": false,
+    "files_sha256": {
+      "arcadia-studio.exe": "78548e93d4b57130ed507ed0f29eddbdbafb4721b38b0cd6d06101d5324114dd",
+      "libunwind.dll": "aa282fa47bb2c4e210cea5e470cdbdca58568f0be0bc73e404d86ab9cd95ef6a"
+    }
+  }
+}

harness/experiments/grid-cache-20260925/desktop-build-02.log

@@ -0,0 +1,2 @@
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `dev` profile [unoptimized] target(s) in 2m 15s

harness/experiments/grid-cache-20260925/grid-clippy-01.log

@@ -0,0 +1,25 @@
+    Checking oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+error: using `chunks_exact` with a constant chunk size
+   --> crates\oa-desktop\src\diagram\grid\tests.rs:231:10
+    |
+231 |         .chunks_exact(4)
+    |          ^^^^^^^^^^^^^^^ help: consider using `as_chunks` instead: `as_chunks::<4>().0.iter()`
+    |
+    = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.98.0/index.html#chunks_exact_to_as_chunks
+    = note: `-D clippy::chunks-exact-to-as-chunks` implied by `-D warnings`
+    = help: to override `-D warnings` add `#[allow(clippy::chunks_exact_to_as_chunks)]`
+
+error: using `chunks_exact` with a constant chunk size
+   --> crates\oa-desktop\src\diagram\grid\tests.rs:232:21
+    |
+232 |         .zip(actual.chunks_exact(4))
+    |                     ^^^^^^^^^^^^^^^
+    |
+help: consider using `as_chunks::<4>()` instead
+   --> crates\oa-desktop\src\diagram\grid\tests.rs:232:21
+    |
+232 |         .zip(actual.chunks_exact(4))
+    |                     ^^^^^^^^^^^^^^^
+    = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.98.0/index.html#chunks_exact_to_as_chunks
+
+error: could not compile `oa-desktop` (bin "arcadia-studio" test) due to 2 previous errors

harness/experiments/grid-cache-20260925/grid-clippy-02.log

@@ -0,0 +1,2 @@
+    Checking oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `dev` profile [unoptimized] target(s) in 2m 01s

harness/experiments/grid-cache-20260925/grid-cold-01.log

@@ -0,0 +1,69 @@
+renderer=wgpu n=20; construction only, unoptimized linked dependencies; NOT native FPS
+size=1900x660 zoom=1
+Original pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Original pan=0,0 changed_pixels=0 max_channel_delta=0
+Original pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Original changing_pan n=20 p50_ms=61.0564 p95_ms=111.2137 max_ms=111.2137
+Template pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Template pan=0,0 changed_pixels=0 max_channel_delta=0
+Template pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Template changing_pan n=20 p50_ms=55.3975 p95_ms=73.8790 max_ms=73.8790
+Column pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Column pan=0,0 changed_pixels=0 max_channel_delta=0
+Column pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Column changing_pan n=20 p50_ms=54.3594 p95_ms=69.6607 max_ms=69.6607
+Square pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Square pan=0,0 changed_pixels=0 max_channel_delta=0
+Square pan=6.125,-8.5 changed_pixels=4266 max_channel_delta=7
+Square changing_pan n=20 p50_ms=3.5527 p95_ms=5.6911 max_ms=5.6911
+size=1900x660 zoom=0.5
+Original pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Original pan=0,0 changed_pixels=0 max_channel_delta=0
+Original pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Original changing_pan n=20 p50_ms=215.8919 p95_ms=253.9666 max_ms=253.9666
+Template pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Template pan=0,0 changed_pixels=0 max_channel_delta=0
+Template pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Template changing_pan n=20 p50_ms=162.3073 p95_ms=212.2833 max_ms=212.2833
+Column pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Column pan=0,0 changed_pixels=0 max_channel_delta=0
+Column pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Column changing_pan n=20 p50_ms=158.5968 p95_ms=449.6066 max_ms=449.6066
+Square pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Square pan=0,0 changed_pixels=0 max_channel_delta=0
+Square pan=6.125,-8.5 changed_pixels=12784 max_channel_delta=7
+Square changing_pan n=20 p50_ms=7.5699 p95_ms=13.3416 max_ms=13.3416
+size=1440x900 zoom=1
+Original pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Original pan=0,0 changed_pixels=0 max_channel_delta=0
+Original pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Original changing_pan n=20 p50_ms=60.1683 p95_ms=88.4967 max_ms=88.4967
+Template pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Template pan=0,0 changed_pixels=0 max_channel_delta=0
+Template pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Template changing_pan n=20 p50_ms=43.3860 p95_ms=53.1866 max_ms=53.1866
+Column pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Column pan=0,0 changed_pixels=0 max_channel_delta=0
+Column pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Column changing_pan n=20 p50_ms=60.8198 p95_ms=80.8932 max_ms=80.8932
+Square pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Square pan=0,0 changed_pixels=0 max_channel_delta=0
+Square pan=6.125,-8.5 changed_pixels=4440 max_channel_delta=7
+Square changing_pan n=20 p50_ms=2.0340 p95_ms=4.0620 max_ms=4.0620
+size=1440x900 zoom=0.5
+Original pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Original pan=0,0 changed_pixels=0 max_channel_delta=0
+Original pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Original changing_pan n=20 p50_ms=165.2049 p95_ms=203.5331 max_ms=203.5331
+Template pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Template pan=0,0 changed_pixels=0 max_channel_delta=0
+Template pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Template changing_pan n=20 p50_ms=133.3420 p95_ms=143.9790 max_ms=143.9790
+Column pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Column pan=0,0 changed_pixels=0 max_channel_delta=0
+Column pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+Column changing_pan n=20 p50_ms=143.1489 p95_ms=155.3680 max_ms=155.3680
+Square pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+Square pan=0,0 changed_pixels=0 max_channel_delta=0
+Square pan=6.125,-8.5 changed_pixels=13184 max_channel_delta=7
+Square changing_pan n=20 p50_ms=6.8178 p95_ms=10.8775 max_ms=10.8775

harness/experiments/grid-cache-20260925/grid-performance-01.log

@@ -0,0 +1,33 @@
+renderer=wgpu samples=20; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation
+
+size=1900x660 zoom=1 dots=2240
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=67.8095 p95_ms=77.2227 max_ms=77.2227
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0002 max_ms=0.0002
+fresh_geometry_and_screenshot: n=20 p50_ms=171.4916 p95_ms=231.2029 max_ms=231.2029
+cached_geometry_and_screenshot: n=20 p50_ms=99.1916 p95_ms=125.0517 max_ms=125.0517
+cache_forced_miss_geometry: n=20 p50_ms=65.6279 p95_ms=75.6531 max_ms=75.6531
+
+size=1900x660 zoom=0.5 dots=6528
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=192.5581 p95_ms=237.9956 max_ms=237.9956
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0009 max_ms=0.0009
+fresh_geometry_and_screenshot: n=20 p50_ms=328.0257 p95_ms=498.0908 max_ms=498.0908
+cached_geometry_and_screenshot: n=20 p50_ms=108.5102 p95_ms=119.6021 max_ms=119.6021
+cache_forced_miss_geometry: n=20 p50_ms=183.2740 p95_ms=212.6681 max_ms=212.6681
+
+size=1440x900 zoom=1 dots=2318
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=66.2206 p95_ms=89.5746 max_ms=89.5746
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0010 max_ms=0.0010
+fresh_geometry_and_screenshot: n=20 p50_ms=194.1484 p95_ms=445.2525 max_ms=445.2525
+cached_geometry_and_screenshot: n=20 p50_ms=113.8430 p95_ms=152.8658 max_ms=152.8658
+cache_forced_miss_geometry: n=20 p50_ms=81.6705 p95_ms=200.7735 max_ms=200.7735
+
+size=1440x900 zoom=0.5 dots=6695
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=219.1771 p95_ms=270.8434 max_ms=270.8434
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0003 max_ms=0.0003
+fresh_geometry_and_screenshot: n=20 p50_ms=387.7051 p95_ms=600.4906 max_ms=600.4906
+cached_geometry_and_screenshot: n=20 p50_ms=119.9417 p95_ms=157.2978 max_ms=157.2978
+cache_forced_miss_geometry: n=20 p50_ms=193.8187 p95_ms=222.6229 max_ms=222.6229

harness/experiments/grid-cache-20260925/grid-performance-02.log

@@ -0,0 +1,41 @@
+renderer=wgpu samples=20; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation
+
+size=1900x660 zoom=1 dots=2240
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=63.8161 p95_ms=74.3558 max_ms=74.3558
+batched_geometry: n=20 p50_ms=280.9291 p95_ms=361.9218 max_ms=361.9218
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0004 max_ms=0.0004
+fresh_geometry_and_screenshot: n=20 p50_ms=203.0484 p95_ms=314.9968 max_ms=314.9968
+cached_geometry_and_screenshot: n=20 p50_ms=109.2162 p95_ms=470.8047 max_ms=470.8047
+cache_forced_miss_geometry: n=20 p50_ms=73.1544 p95_ms=112.9079 max_ms=112.9079
+
+size=1900x660 zoom=0.5 dots=6528
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=178.2363 p95_ms=204.1913 max_ms=204.1913
+batched_geometry: n=20 p50_ms=1225.5328 p95_ms=1791.5758 max_ms=1791.5758
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0008 max_ms=0.0008
+fresh_geometry_and_screenshot: n=20 p50_ms=281.4035 p95_ms=308.5933 max_ms=308.5933
+cached_geometry_and_screenshot: n=20 p50_ms=100.8220 p95_ms=114.5026 max_ms=114.5026
+cache_forced_miss_geometry: n=20 p50_ms=179.6717 p95_ms=319.2162 max_ms=319.2162
+
+size=1440x900 zoom=1 dots=2318
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=67.1604 p95_ms=76.3298 max_ms=76.3298
+batched_geometry: n=20 p50_ms=274.6607 p95_ms=551.4707 max_ms=551.4707
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0003 max_ms=0.0003
+fresh_geometry_and_screenshot: n=20 p50_ms=168.4817 p95_ms=294.9456 max_ms=294.9456
+cached_geometry_and_screenshot: n=20 p50_ms=92.0521 p95_ms=105.3303 max_ms=105.3303
+cache_forced_miss_geometry: n=20 p50_ms=70.1733 p95_ms=83.6053 max_ms=83.6053
+
+size=1440x900 zoom=0.5 dots=6695
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=177.7526 p95_ms=205.8862 max_ms=205.8862
+batched_geometry: n=20 p50_ms=1012.6393 p95_ms=1103.8729 max_ms=1103.8729
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0006 max_ms=0.0006
+fresh_geometry_and_screenshot: n=20 p50_ms=293.3138 p95_ms=315.0118 max_ms=315.0118
+cached_geometry_and_screenshot: n=20 p50_ms=110.6309 p95_ms=127.6823 max_ms=127.6823
+cache_forced_miss_geometry: n=20 p50_ms=195.3297 p95_ms=327.8771 max_ms=327.8771

harness/experiments/grid-cache-20260925/grid-performance-03.log

@@ -0,0 +1,45 @@
+renderer=wgpu samples=20; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation
+
+size=1900x660 zoom=1 dots=2240
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=70.2238 p95_ms=101.8816 max_ms=101.8816
+production_cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0005 max_ms=0.0005
+production_changing_pan_geometry: n=20 p50_ms=74.2265 p95_ms=150.4436 max_ms=150.4436
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0002 max_ms=0.0002
+fresh_geometry_and_screenshot: n=20 p50_ms=179.3216 p95_ms=272.4518 max_ms=272.4518
+cached_geometry_and_screenshot: n=20 p50_ms=108.8949 p95_ms=138.2430 max_ms=138.2430
+cache_forced_miss_geometry: n=20 p50_ms=73.2982 p95_ms=229.4395 max_ms=229.4395
+
+size=1900x660 zoom=0.5 dots=6528
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=190.5914 p95_ms=245.6332 max_ms=245.6332
+production_cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0004 max_ms=0.0004
+production_changing_pan_geometry: n=20 p50_ms=200.1888 p95_ms=243.7068 max_ms=243.7068
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0002 max_ms=0.0002
+fresh_geometry_and_screenshot: n=20 p50_ms=356.6151 p95_ms=438.3689 max_ms=438.3689
+cached_geometry_and_screenshot: n=20 p50_ms=151.2161 p95_ms=236.6296 max_ms=236.6296
+cache_forced_miss_geometry: n=20 p50_ms=198.4648 p95_ms=312.0322 max_ms=312.0322
+
+size=1440x900 zoom=1 dots=2318
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
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+production_cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0010 max_ms=0.0010
+production_changing_pan_geometry: n=20 p50_ms=61.6783 p95_ms=79.8293 max_ms=79.8293
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0003 max_ms=0.0003
+fresh_geometry_and_screenshot: n=20 p50_ms=168.7804 p95_ms=206.0726 max_ms=206.0726
+cached_geometry_and_screenshot: n=20 p50_ms=114.7579 p95_ms=130.0840 max_ms=130.0840
+cache_forced_miss_geometry: n=20 p50_ms=103.6019 p95_ms=215.1691 max_ms=215.1691
+
+size=1440x900 zoom=0.5 dots=6695
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=202.9283 p95_ms=247.2353 max_ms=247.2353
+production_cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0004 max_ms=0.0004
+production_changing_pan_geometry: n=20 p50_ms=223.5437 p95_ms=243.7359 max_ms=243.7359
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0002 max_ms=0.0002
+fresh_geometry_and_screenshot: n=20 p50_ms=299.4320 p95_ms=359.2924 max_ms=359.2924
+cached_geometry_and_screenshot: n=20 p50_ms=113.6960 p95_ms=180.7261 max_ms=180.7261
+cache_forced_miss_geometry: n=20 p50_ms=191.9370 p95_ms=294.2203 max_ms=294.2203

harness/experiments/grid-cache-20260925/grid-performance-04.log

@@ -0,0 +1,45 @@
+renderer=wgpu samples=20; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation
+
+size=1900x660 zoom=1 dots=2240
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=61.8281 p95_ms=68.9849 max_ms=68.9849
+production_cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0002 max_ms=0.0002
+production_changing_pan_geometry: n=20 p50_ms=59.2995 p95_ms=69.6670 max_ms=69.6670
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0029 max_ms=0.0029
+fresh_geometry_and_screenshot: n=20 p50_ms=136.3939 p95_ms=160.0453 max_ms=160.0453
+cached_geometry_and_screenshot: n=20 p50_ms=82.0448 p95_ms=105.5853 max_ms=105.5853
+cache_forced_miss_geometry: n=20 p50_ms=52.1529 p95_ms=58.0832 max_ms=58.0832
+
+size=1900x660 zoom=0.5 dots=6528
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
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+production_cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0002 max_ms=0.0002
+production_changing_pan_geometry: n=20 p50_ms=163.4359 p95_ms=262.5349 max_ms=262.5349
+cached_geometry: n=20 p50_ms=0.0002 p95_ms=0.0002 max_ms=0.0002
+fresh_geometry_and_screenshot: n=20 p50_ms=226.3661 p95_ms=247.0635 max_ms=247.0635
+cached_geometry_and_screenshot: n=20 p50_ms=78.5761 p95_ms=99.7537 max_ms=99.7537
+cache_forced_miss_geometry: n=20 p50_ms=154.7299 p95_ms=177.8883 max_ms=177.8883
+
+size=1440x900 zoom=1 dots=2318
+batched_rgba_byte_differences=0
+pixel_parity=cold_and_warm_exact
+fresh_geometry: n=20 p50_ms=50.5385 p95_ms=57.4277 max_ms=57.4277
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+production_changing_pan_geometry: n=20 p50_ms=53.5840 p95_ms=60.8569 max_ms=60.8569
+cached_geometry: n=20 p50_ms=0.0001 p95_ms=0.0005 max_ms=0.0005
+fresh_geometry_and_screenshot: n=20 p50_ms=124.3827 p95_ms=140.3617 max_ms=140.3617
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+cache_forced_miss_geometry: n=20 p50_ms=54.7114 p95_ms=61.8326 max_ms=61.8326
+
+size=1440x900 zoom=0.5 dots=6695
+batched_rgba_byte_differences=0
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+cache_forced_miss_geometry: n=20 p50_ms=155.4512 p95_ms=163.8325 max_ms=163.8325

harness/experiments/grid-cache-20260925/grid-phase-01.log

@@ -0,0 +1,96 @@
+renderer=wgpu; phase-cache prototype; NOT native FPS
+size=1900x660 zoom=1 step=24
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
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harness/experiments/grid-cache-20260925/grid-phase-diagnostic-01.log

@@ -0,0 +1,32 @@
+renderer=wgpu; phase-cache prototype; NOT native FPS
+size=301.5x211.25 zoom=0.73 step=17.52
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
+difference_xy=301,26 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,27 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,62 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,80 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,97 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,115 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,132 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,150 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,167 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,184 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,185 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,202 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
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+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0011 p95_ms=0.0019 max_ms=0.0019
+cache_builds=1

harness/experiments/grid-cache-20260925/grid-phase-opaque-01.log

@@ -0,0 +1,100 @@
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+scale=1.25 pan=17.395,17.27 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=2 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-13.25,9.75 changed_pixels=1 max_channel_delta=6
+scale=2 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=2 pan=17.395,17.27 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+cached=false construct_and_submit changing_pan n=20 p50_ms=5.4797 p95_ms=6.8957 max_ms=6.8957
+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0007 p95_ms=0.0008 max_ms=0.0008
+cache_builds=1

harness/experiments/grid-cache-20260925/grid-phase-replay-01.log

@@ -0,0 +1,127 @@
+renderer=wgpu; phase-cache prototype; NOT native FPS
+size=1900x660 zoom=1 step=24
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1 pan=23.875,23.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=23.875,23.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=2 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=2 pan=23.875,23.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+cached=false construct_and_submit changing_pan n=20 p50_ms=68.3424 p95_ms=88.0883 max_ms=88.0883
+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0010 p95_ms=0.0012 max_ms=0.0012
+cache_builds=1
+cached=false construct_submit_screenshot changing_pan n=8 p50_ms=249.7269 min_ms=216.9378 max_ms=267.1425
+cached=true construct_submit_screenshot changing_pan n=8 p50_ms=215.6865 min_ms=177.7329 max_ms=262.5719
+size=1900x660 zoom=0.5 step=14
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1 pan=13.875,13.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=13.875,13.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=2 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=2 pan=13.875,13.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+cached=false construct_and_submit changing_pan n=20 p50_ms=190.0141 p95_ms=231.4193 max_ms=231.4193
+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0008 p95_ms=0.0008 max_ms=0.0008
+cache_builds=1
+size=1440x900 zoom=1 step=24
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1 pan=23.875,23.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=23.875,23.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=2 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=2 pan=23.875,23.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+cached=false construct_and_submit changing_pan n=20 p50_ms=72.2449 p95_ms=86.5021 max_ms=86.5021
+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0008 p95_ms=0.0008 max_ms=0.0008
+cache_builds=1
+size=1440x900 zoom=0.5 step=14
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1 pan=13.875,13.75 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=13.875,13.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=2 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=2 pan=13.875,13.75 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+cached=false construct_and_submit changing_pan n=20 p50_ms=209.4728 p95_ms=329.0977 max_ms=329.0977
+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0008 p95_ms=0.0009 max_ms=0.0009
+cache_builds=1
+cached=false construct_submit_screenshot changing_pan n=8 p50_ms=384.7680 min_ms=347.4879 max_ms=420.2894
+cached=true construct_submit_screenshot changing_pan n=8 p50_ms=164.1611 min_ms=150.1276 max_ms=186.4567
+size=301.5x211.25 zoom=0.73 step=17.52
+scale=1 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-13.25,9.75 changed_pixels=12 max_channel_delta=1
+difference_xy=301,26 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,27 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,62 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,80 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,97 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,115 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,132 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,150 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,167 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,184 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,185 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+difference_xy=301,202 expected=[240, 243, 247, 255] actual=[240, 243, 246, 255]
+scale=1 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1 pan=17.395,17.27 changed_pixels=0 max_channel_delta=0
+scale=1 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=17.395,17.27 changed_pixels=0 max_channel_delta=0
+scale=1.25 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+scale=2 pan=0,0 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-13.25,9.75 changed_pixels=1 max_channel_delta=6
+difference_xy=149,263 expected=[240, 243, 246, 255] actual=[246, 248, 251, 255]
+scale=2 pan=6.125,-8.5 changed_pixels=0 max_channel_delta=0
+scale=2 pan=17.395,17.27 changed_pixels=0 max_channel_delta=0
+scale=2 pan=-0.125,0.125 changed_pixels=0 max_channel_delta=0
+cached=false construct_and_submit changing_pan n=20 p50_ms=5.5680 p95_ms=7.0634 max_ms=7.0634
+cached=true construct_and_submit changing_pan n=20 p50_ms=0.0007 p95_ms=0.0008 max_ms=0.0008
+cache_builds=1
+original_sequence_complete; beginning same-renderer repeat controls
+comparison=old/old repetition=1 size=301.5x211.25 scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=cached/cached repetition=1 size=301.5x211.25 scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=old/old repetition=1 size=301.5x211.25 scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=cached/cached repetition=1 size=301.5x211.25 scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=old/old repetition=2 size=301.5x211.25 scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=cached/cached repetition=2 size=301.5x211.25 scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=old/old repetition=2 size=301.5x211.25 scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=cached/cached repetition=2 size=301.5x211.25 scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=old/old repetition=3 size=301.5x211.25 scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=cached/cached repetition=3 size=301.5x211.25 scale=1 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=old/old repetition=3 size=301.5x211.25 scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+comparison=cached/cached repetition=3 size=301.5x211.25 scale=2 pan=-13.25,9.75 changed_pixels=0 max_channel_delta=0
+control_cache_builds=1

harness/experiments/grid-cache-20260925/grid-tests-01.log

@@ -0,0 +1,11 @@
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `test` profile [unoptimized] target(s) in 4m 23s
+     Running unittests src\main.rs (C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\arcadia_studio-c5b42126ba36cd38.exe)
+
+running 3 tests
+test diagram::grid::tests::actual_canvas_keeps_background_cached_while_selection_and_revision_change ... ok
+test diagram::grid::tests::cache_reuses_unchanged_inputs_and_rebuilds_for_each_camera_or_size_change ... ok
+test diagram::grid::tests::cached_background_preserves_pixels_and_live_foreground_across_camera_and_size_changes ... ok
+
+test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 1547 filtered out; finished in 2.97s
+

harness/experiments/grid-cache-20260925/grid-tests-02.log

@@ -0,0 +1,11 @@
+   Compiling oa-desktop v0.2.0 (C:\Users\User\Documents\Git\ARCADIA-Studio\.local\drag-out-01a0d6fd\crates\oa-desktop)
+    Finished `test` profile [unoptimized] target(s) in 3m 31s
+     Running unittests src\main.rs (C:/Users/User/Documents/Git/ARCADIA-Studio/target\debug\deps\arcadia_studio-c5b42126ba36cd38.exe)
+
+running 3 tests
+test diagram::grid::tests::actual_canvas_keeps_background_cached_while_selection_and_revision_change ... ok
+test diagram::grid::tests::cache_reuses_unchanged_inputs_and_rebuilds_for_each_camera_or_size_change ... ok
+test diagram::grid::tests::cached_background_preserves_pixels_and_live_foreground_across_camera_and_size_changes ... ok
+
+test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 1547 filtered out; finished in 4.13s
+

harness/experiments/grid-cache-20260925/grid_render_probe.rs

@@ -0,0 +1,163 @@
+//! Headless rendering experiment; creates no desktop window and sends no input.
+use iced::advanced::{
+    graphics::geometry::Renderer as _,
+    renderer::{Headless, Renderer as _},
+};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+
+fn paint(frame: &mut Frame, size: Size, zoom: f32, pan: Vector) {
+    frame.fill_rectangle(Point::ORIGIN, size, BG);
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            frame.fill(
+                &Path::circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65),
+                DOT,
+            );
+        }
+    }
+}
+fn fresh(renderer: &Renderer, size: Size, zoom: f32, pan: Vector) -> Geometry {
+    let mut frame = Frame::new(renderer, size);
+    paint(&mut frame, size, zoom, pan);
+    frame.into_geometry()
+}
+fn batched(renderer: &Renderer, size: Size, zoom: f32, pan: Vector) -> Geometry {
+    let mut frame = Frame::new(renderer, size);
+    frame.fill_rectangle(Point::ORIGIN, size, BG);
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    let path = Path::new(|p| {
+        for x in 0..(size.width / step) as i32 + 1 {
+            for y in 0..(size.height / step) as i32 + 1 {
+                p.circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65);
+                p.close();
+            }
+        }
+    });
+    frame.fill(&path, DOT);
+    frame.into_geometry()
+}
+fn screenshot(renderer: &mut Renderer, size: Size, geometry: Geometry) -> Vec<u8> {
+    renderer.reset(Rectangle::with_size(size));
+    renderer.draw_geometry(geometry);
+    Headless::screenshot(
+        renderer,
+        Size::new(size.width as u32, size.height as u32),
+        1.,
+        BG,
+    )
+}
+fn measure<T>(label: &str, n: usize, mut f: impl FnMut() -> T) {
+    for _ in 0..3 {
+        black_box(f());
+    }
+    let mut values = Vec::new();
+    for _ in 0..n {
+        let now = Instant::now();
+        let value = black_box(f());
+        values.push(now.elapsed().as_secs_f64() * 1000.);
+        drop(value);
+    }
+    values.sort_by(f64::total_cmp);
+    let at = |p: f64| values[((n - 1) as f64 * p).ceil() as usize];
+    println!(
+        "{label}: n={n} p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+        at(0.5),
+        at(0.95),
+        values[n - 1]
+    );
+}
+fn main() {
+    let n = std::env::args()
+        .nth(1)
+        .map(|s| s.parse::<usize>().unwrap())
+        .unwrap_or(20)
+        .max(1);
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut renderer = runtime
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .expect("headless production renderer");
+    println!(
+        "renderer={} samples={n}; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation",
+        renderer.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+    ] {
+        let pan = Vector::new(-13.25, 9.75);
+        let cache = Cache::new();
+        let calls = Cell::new(0);
+        let cached = |r: &Renderer| {
+            cache.draw(r, size, |f| {
+                calls.set(calls.get() + 1);
+                paint(f, size, zoom, pan);
+            })
+        };
+        let step = (24f32 * zoom).max(14.);
+        println!(
+            "\nsize={}x{} zoom={zoom} dots={}",
+            size.width,
+            size.height,
+            ((size.width / step) as i32 + 1) * ((size.height / step) as i32 + 1)
+        );
+        let baseline = fresh(&renderer, size, zoom, pan);
+        let baseline_pixels = screenshot(&mut renderer, size, baseline);
+        let geometry = batched(&renderer, size, zoom, pan);
+        let pixels = screenshot(&mut renderer, size, geometry);
+        let differences = baseline_pixels
+            .iter()
+            .zip(&pixels)
+            .filter(|(a, b)| a != b)
+            .count();
+        println!("batched_rgba_byte_differences={differences}");
+        assert_eq!(
+            differences, 0,
+            "batched path must preserve exact grid pixels"
+        );
+        let geometry = cached(&renderer);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, geometry));
+        let geometry = cached(&renderer);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, geometry));
+        assert_eq!(calls.get(), 1);
+        println!("pixel_parity=cold_and_warm_exact");
+        measure("fresh_geometry", n, || fresh(&renderer, size, zoom, pan));
+        measure("batched_geometry", n, || {
+            batched(&renderer, size, zoom, pan)
+        });
+        measure("cached_geometry", n, || cached(&renderer));
+        assert_eq!(calls.get(), 1, "identical camera must reuse geometry");
+        measure("fresh_geometry_and_screenshot", n, || {
+            let g = fresh(&renderer, size, zoom, pan);
+            screenshot(&mut renderer, size, g)
+        });
+        measure("cached_geometry_and_screenshot", n, || {
+            let g = cached(&renderer);
+            screenshot(&mut renderer, size, g)
+        });
+        measure("cache_forced_miss_geometry", n, || {
+            cache.clear();
+            cached(&renderer)
+        });
+    }
+}

harness/experiments/grid-cache-20260925/grid_render_probe_v1.rs

@@ -0,0 +1,131 @@
+//! Headless rendering experiment; creates no desktop window and sends no input.
+use iced::advanced::{
+    graphics::geometry::Renderer as _,
+    renderer::{Headless, Renderer as _},
+};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+
+fn paint(frame: &mut Frame, size: Size, zoom: f32, pan: Vector) {
+    frame.fill_rectangle(Point::ORIGIN, size, BG);
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            frame.fill(
+                &Path::circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65),
+                DOT,
+            );
+        }
+    }
+}
+fn fresh(renderer: &Renderer, size: Size, zoom: f32, pan: Vector) -> Geometry {
+    let mut frame = Frame::new(renderer, size);
+    paint(&mut frame, size, zoom, pan);
+    frame.into_geometry()
+}
+fn screenshot(renderer: &mut Renderer, size: Size, geometry: Geometry) -> Vec<u8> {
+    renderer.reset(Rectangle::with_size(size));
+    renderer.draw_geometry(geometry);
+    Headless::screenshot(
+        renderer,
+        Size::new(size.width as u32, size.height as u32),
+        1.,
+        BG,
+    )
+}
+fn measure<T>(label: &str, n: usize, mut f: impl FnMut() -> T) {
+    for _ in 0..3 {
+        black_box(f());
+    }
+    let mut values = Vec::new();
+    for _ in 0..n {
+        let now = Instant::now();
+        let value = black_box(f());
+        values.push(now.elapsed().as_secs_f64() * 1000.);
+        drop(value);
+    }
+    values.sort_by(f64::total_cmp);
+    let at = |p: f64| values[((n - 1) as f64 * p).ceil() as usize];
+    println!(
+        "{label}: n={n} p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+        at(0.5),
+        at(0.95),
+        values[n - 1]
+    );
+}
+fn main() {
+    let n = std::env::args()
+        .nth(1)
+        .map(|s| s.parse::<usize>().unwrap())
+        .unwrap_or(20)
+        .max(1);
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut renderer = runtime
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .expect("headless production renderer");
+    println!(
+        "renderer={} samples={n}; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation",
+        renderer.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+    ] {
+        let pan = Vector::new(-13.25, 9.75);
+        let cache = Cache::new();
+        let calls = Cell::new(0);
+        let cached = |r: &Renderer| {
+            cache.draw(r, size, |f| {
+                calls.set(calls.get() + 1);
+                paint(f, size, zoom, pan);
+            })
+        };
+        let step = (24f32 * zoom).max(14.);
+        println!(
+            "\nsize={}x{} zoom={zoom} dots={}",
+            size.width,
+            size.height,
+            ((size.width / step) as i32 + 1) * ((size.height / step) as i32 + 1)
+        );
+        let baseline = fresh(&renderer, size, zoom, pan);
+        let baseline_pixels = screenshot(&mut renderer, size, baseline);
+        let geometry = cached(&renderer);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, geometry));
+        let geometry = cached(&renderer);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, geometry));
+        assert_eq!(calls.get(), 1);
+        println!("pixel_parity=cold_and_warm_exact");
+        measure("fresh_geometry", n, || fresh(&renderer, size, zoom, pan));
+        measure("cached_geometry", n, || cached(&renderer));
+        assert_eq!(calls.get(), 1, "identical camera must reuse geometry");
+        measure("fresh_geometry_and_screenshot", n, || {
+            let g = fresh(&renderer, size, zoom, pan);
+            screenshot(&mut renderer, size, g)
+        });
+        measure("cached_geometry_and_screenshot", n, || {
+            let g = cached(&renderer);
+            screenshot(&mut renderer, size, g)
+        });
+        measure("cache_forced_miss_geometry", n, || {
+            cache.clear();
+            cached(&renderer)
+        });
+    }
+}

harness/experiments/grid-cache-20260925/independent-review.md

@@ -0,0 +1,42 @@
+# Independent cache and evaluator review
+
+Read-only GPT-6 Astra review of
+`636093aae67aa48fa1d35e403a205227e81d04de`, 2026-09-25. The reviewer did not
+edit files, compile, launch a desktop window or control the user interface.
+
+No concrete cache-key, lifetime or drawing-order defect was found. The review
+checked Iced 0.14 source as well as the application: Iced compares exact cache
+size, explicit camera changes clear geometry, and context/gesture retirement
+retains the model-independent grid. Normal canvas state survives view rebuilds;
+the focus wrapper's suspension reset causes a safe cold miss. Cached and live
+mesh submissions retain their invocation order. Background geometry has no
+text/images, and existing model transforms still apply to the live scene.
+
+The evaluator uses an independent copy of the original grid painter, rather
+than calling the candidate's painter to produce its expected image. It compares
+the former combined frame with the split cached background, including opaque
+and translucent foreground, text, overlay, fractional inputs and live edits.
+The real DiagramCanvas check demonstrates changing selection/model revision
+pixels while the grid construction count remains one, then checks pan/resize
+invalidation. It exercises retained-state drawing and scene invalidation;
+event-driven native gesture acceptance is outside that test.
+
+The reviewer inspected `grid-tests-01.log`: all three tests pass, none fail or
+are ignored, 1,547 are filtered, and execution takes 2.97s. Source identity is
+provided by the accompanying run record and clean tracked implementation, not
+by an embedded hash in the Cargo log. Full-suite/build/Clippy results published
+later remain separate evidence and must be read in their own logs.
+
+The measurements support avoiding repeated grid construction for an unchanged
+camera. They do not establish native FPS, performance on another renderer, or
+improvement during continuously changing pan/zoom. No broad final application
+or release acceptance is claimed by this review.
+
+A second read-only audit checked the full desktop log's 1,550 distinct names,
+1,543 passes and seven ignored cases against `context.json`. It verified all
+three recorded log hashes, driver-source hash, committed grid blob, linked Iced
+and Tokio libraries, timing tables, sample method and rejected-batch ranges.
+It did not independently verify the probe executable, execution chronology,
+Clippy/build gates or environment assertions. It clarified that run 04's generic
+cold-and-warm marker is not a production-cache warm-pixel check; that assertion
+belongs to the separate committed tests.

harness/experiments/grid-cache-20260925/phase_grid_diagnostic.rs

@@ -0,0 +1,209 @@
+//! Renderer-level phase translation experiment, not application code.
+use iced::advanced::{Renderer as _, graphics::geometry::Renderer as _, renderer::Headless};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+fn dots(f: &mut Frame, size: Size, step: f32, phase: Vector) {
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            f.fill(
+                &Path::circle(
+                    Point::new(phase.x + x as f32 * step, phase.y + y as f32 * step),
+                    0.65,
+                ),
+                DOT,
+            );
+        }
+    }
+}
+fn old(r: &Renderer, size: Size, step: f32, phase: Vector) -> Geometry {
+    let mut f = Frame::new(r, size);
+    f.fill_rectangle(Point::ORIGIN, size, BG);
+    dots(&mut f, size, step, phase);
+    f.into_geometry()
+}
+fn phase(r: &Renderer, cache: &Cache, size: Size, step: f32, builds: &Cell<usize>) -> Geometry {
+    cache.draw_with_bounds(
+        r,
+        Rectangle {
+            x: -step,
+            y: -step,
+            width: size.width + 3. * step,
+            height: size.height + 3. * step,
+        },
+        |f| {
+            builds.set(builds.get() + 1);
+            f.fill_rectangle(
+                Point::new(-step, -step),
+                Size::new(size.width + 3. * step, size.height + 3. * step),
+                BG,
+            );
+            dots(f, size, step, Vector::ZERO);
+        },
+    )
+}
+fn submit(r: &mut Renderer, size: Size, g: Geometry, pan: Vector) {
+    r.with_layer(Rectangle::with_size(size), |r| {
+        r.with_translation(pan, |r| r.draw_geometry(g))
+    });
+}
+fn shot(r: &mut Renderer, size: Size, scale: f32) -> Vec<u8> {
+    Headless::screenshot(
+        r,
+        Size::new(
+            (size.width * scale).ceil() as u32,
+            (size.height * scale).ceil() as u32,
+        ),
+        scale,
+        BG,
+    )
+}
+fn main() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut r = rt
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .unwrap();
+    println!(
+        "renderer={}; phase-cache prototype; NOT native FPS",
+        r.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+        (Size::new(301.5, 211.25), 0.73),
+    ] {
+        if size.width != 301.5 {
+            continue;
+        }
+        let step = (24f32 * zoom).max(14.);
+        let cache = Cache::new();
+        let builds = Cell::new(0);
+        println!(
+            "size={}x{} zoom={zoom} step={step}",
+            size.width, size.height
+        );
+        for scale in [1., 1.25, 2.] {
+            for pan in [
+                Vector::ZERO,
+                Vector::new(-13.25, 9.75),
+                Vector::new(6.125, -8.5),
+                Vector::new(step - 0.125, step - 0.25),
+                Vector::new(-0.125, 0.125),
+            ] {
+                let offset = Vector::new(pan.x.rem_euclid(step), pan.y.rem_euclid(step));
+                r.reset(Rectangle::with_size(size));
+                let g = old(&r, size, step, offset);
+                r.draw_geometry(g);
+                let expected = shot(&mut r, size, scale);
+                r.reset(Rectangle::with_size(size));
+                let g = phase(&r, &cache, size, step, &builds);
+                submit(&mut r, size, g, offset);
+                let actual = shot(&mut r, size, scale);
+                assert_eq!(expected.len(), actual.len());
+                for (index, (a, b)) in expected
+                    .chunks_exact(4)
+                    .zip(actual.chunks_exact(4))
+                    .enumerate()
+                    .filter(|(_, (a, b))| a != b)
+                    .take(20)
+                {
+                    println!(
+                        "difference_xy={},{} expected={a:?} actual={b:?}",
+                        index % (size.width * scale).ceil() as usize,
+                        index / (size.width * scale).ceil() as usize
+                    );
+                }
+                let changed = expected
+                    .chunks_exact(4)
+                    .zip(actual.chunks_exact(4))
+                    .filter(|(a, b)| a != b)
+                    .count();
+                let max = expected
+                    .iter()
+                    .zip(&actual)
+                    .map(|(a, b)| a.abs_diff(*b))
+                    .max()
+                    .unwrap_or(0);
+                println!(
+                    "scale={scale} pan={},{} changed_pixels={changed} max_channel_delta={max}",
+                    pan.x, pan.y
+                );
+            }
+        }
+        assert_eq!(builds.get(), 1);
+        for cached in [false, true] {
+            let mut ms = Vec::new();
+            for i in 0..23 {
+                r.reset(Rectangle::with_size(size));
+                let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                let now = Instant::now();
+                let g = if cached {
+                    phase(&r, &cache, size, step, &builds)
+                } else {
+                    old(&r, size, step, offset)
+                };
+                if cached {
+                    submit(&mut r, size, g, offset)
+                } else {
+                    r.draw_geometry(g)
+                };
+                let elapsed = black_box(now.elapsed().as_secs_f64() * 1000.);
+                if i >= 3 {
+                    ms.push(elapsed);
+                }
+            }
+            ms.sort_by(f64::total_cmp);
+            println!(
+                "cached={cached} construct_and_submit changing_pan n=20 p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+                ms[10], ms[19], ms[19]
+            );
+        }
+        println!("cache_builds={}", builds.get());
+        assert_eq!(builds.get(), 1);
+        // Includes backend prepare/upload and readback; still not native presentation.
+        if size.width == 1900. && zoom == 1. || size.width == 1440. && zoom == 0.5 {
+            for cached in [false, true] {
+                let mut ms = Vec::new();
+                for i in 0..10 {
+                    r.reset(Rectangle::with_size(size));
+                    let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                    let now = Instant::now();
+                    let g = if cached {
+                        phase(&r, &cache, size, step, &builds)
+                    } else {
+                        old(&r, size, step, offset)
+                    };
+                    if cached {
+                        submit(&mut r, size, g, offset);
+                    } else {
+                        r.draw_geometry(g);
+                    }
+                    let pixels = black_box(shot(&mut r, size, 1.));
+                    let elapsed = now.elapsed().as_secs_f64() * 1000.;
+                    drop(pixels);
+                    if i >= 2 {
+                        ms.push(elapsed);
+                    }
+                }
+                ms.sort_by(f64::total_cmp);
+                println!(
+                    "cached={cached} construct_submit_screenshot changing_pan n=8 p50_ms={:.4} min_ms={:.4} max_ms={:.4}",
+                    ms[4], ms[0], ms[7]
+                );
+            }
+        }
+    }
+}

harness/experiments/grid-cache-20260925/phase_grid_opaque_probe.rs

@@ -0,0 +1,193 @@
+//! Renderer-level phase translation experiment, not application code.
+use iced::advanced::{Renderer as _, graphics::geometry::Renderer as _, renderer::Headless};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+fn dots(f: &mut Frame, size: Size, step: f32, phase: Vector) {
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            f.fill(
+                &Path::circle(
+                    Point::new(phase.x + x as f32 * step, phase.y + y as f32 * step),
+                    0.65,
+                ),
+                DOT,
+            );
+        }
+    }
+}
+fn old(r: &Renderer, size: Size, step: f32, phase: Vector) -> Geometry {
+    let mut f = Frame::new(r, size);
+    f.fill_rectangle(Point::ORIGIN, size, BG);
+    dots(&mut f, size, step, phase);
+    f.into_geometry()
+}
+fn phase(r: &Renderer, cache: &Cache, size: Size, step: f32, builds: &Cell<usize>) -> Geometry {
+    cache.draw_with_bounds(
+        r,
+        Rectangle {
+            x: -step,
+            y: -step,
+            width: size.width + 3. * step,
+            height: size.height + 3. * step,
+        },
+        |f| {
+            builds.set(builds.get() + 1);
+            f.fill_rectangle(
+                Point::new(-step, -step),
+                Size::new(size.width + 3. * step, size.height + 3. * step),
+                BG,
+            );
+            dots(f, size, step, Vector::ZERO);
+        },
+    )
+}
+fn submit(r: &mut Renderer, size: Size, g: Geometry, pan: Vector) {
+    r.with_layer(Rectangle::with_size(size), |r| {
+        r.with_translation(pan, |r| r.draw_geometry(g))
+    });
+}
+fn shot(r: &mut Renderer, size: Size, scale: f32) -> Vec<u8> {
+    Headless::screenshot(
+        r,
+        Size::new(
+            (size.width * scale).ceil() as u32,
+            (size.height * scale).ceil() as u32,
+        ),
+        scale,
+        BG,
+    )
+}
+fn main() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut r = rt
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .unwrap();
+    println!(
+        "renderer={}; phase-cache prototype; NOT native FPS",
+        r.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+        (Size::new(301.5, 211.25), 0.73),
+    ] {
+        let step = (24f32 * zoom).max(14.);
+        let cache = Cache::new();
+        let builds = Cell::new(0);
+        println!(
+            "size={}x{} zoom={zoom} step={step}",
+            size.width, size.height
+        );
+        for scale in [1., 1.25, 2.] {
+            for pan in [
+                Vector::ZERO,
+                Vector::new(-13.25, 9.75),
+                Vector::new(6.125, -8.5),
+                Vector::new(step - 0.125, step - 0.25),
+                Vector::new(-0.125, 0.125),
+            ] {
+                let offset = Vector::new(pan.x.rem_euclid(step), pan.y.rem_euclid(step));
+                r.reset(Rectangle::with_size(size));
+                let g = old(&r, size, step, offset);
+                r.draw_geometry(g);
+                let expected = shot(&mut r, size, scale);
+                r.reset(Rectangle::with_size(size));
+                let g = phase(&r, &cache, size, step, &builds);
+                submit(&mut r, size, g, offset);
+                let actual = shot(&mut r, size, scale);
+                assert_eq!(expected.len(), actual.len());
+                let changed = expected
+                    .chunks_exact(4)
+                    .zip(actual.chunks_exact(4))
+                    .filter(|(a, b)| a != b)
+                    .count();
+                let max = expected
+                    .iter()
+                    .zip(&actual)
+                    .map(|(a, b)| a.abs_diff(*b))
+                    .max()
+                    .unwrap_or(0);
+                println!(
+                    "scale={scale} pan={},{} changed_pixels={changed} max_channel_delta={max}",
+                    pan.x, pan.y
+                );
+            }
+        }
+        assert_eq!(builds.get(), 1);
+        for cached in [false, true] {
+            let mut ms = Vec::new();
+            for i in 0..23 {
+                r.reset(Rectangle::with_size(size));
+                let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                let now = Instant::now();
+                let g = if cached {
+                    phase(&r, &cache, size, step, &builds)
+                } else {
+                    old(&r, size, step, offset)
+                };
+                if cached {
+                    submit(&mut r, size, g, offset)
+                } else {
+                    r.draw_geometry(g)
+                };
+                let elapsed = black_box(now.elapsed().as_secs_f64() * 1000.);
+                if i >= 3 {
+                    ms.push(elapsed);
+                }
+            }
+            ms.sort_by(f64::total_cmp);
+            println!(
+                "cached={cached} construct_and_submit changing_pan n=20 p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+                ms[10], ms[19], ms[19]
+            );
+        }
+        println!("cache_builds={}", builds.get());
+        assert_eq!(builds.get(), 1);
+        // Includes backend prepare/upload and readback; still not native presentation.
+        if size.width == 1900. && zoom == 1. || size.width == 1440. && zoom == 0.5 {
+            for cached in [false, true] {
+                let mut ms = Vec::new();
+                for i in 0..10 {
+                    r.reset(Rectangle::with_size(size));
+                    let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                    let now = Instant::now();
+                    let g = if cached {
+                        phase(&r, &cache, size, step, &builds)
+                    } else {
+                        old(&r, size, step, offset)
+                    };
+                    if cached {
+                        submit(&mut r, size, g, offset);
+                    } else {
+                        r.draw_geometry(g);
+                    }
+                    let pixels = black_box(shot(&mut r, size, 1.));
+                    let elapsed = now.elapsed().as_secs_f64() * 1000.;
+                    drop(pixels);
+                    if i >= 2 {
+                        ms.push(elapsed);
+                    }
+                }
+                ms.sort_by(f64::total_cmp);
+                println!(
+                    "cached={cached} construct_submit_screenshot changing_pan n=8 p50_ms={:.4} min_ms={:.4} max_ms={:.4}",
+                    ms[4], ms[0], ms[7]
+                );
+            }
+        }
+    }
+}

harness/experiments/grid-cache-20260925/phase_grid_probe_v1.rs

@@ -0,0 +1,160 @@
+//! Renderer-level phase translation experiment, not application code.
+use iced::advanced::{
+    Renderer as _,
+    graphics::geometry::Renderer as _,
+    renderer::{Headless, Renderer as _},
+};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+fn dots(f: &mut Frame, size: Size, step: f32, phase: Vector) {
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            f.fill(
+                &Path::circle(
+                    Point::new(phase.x + x as f32 * step, phase.y + y as f32 * step),
+                    0.65,
+                ),
+                DOT,
+            );
+        }
+    }
+}
+fn old(r: &Renderer, size: Size, step: f32, phase: Vector) -> Geometry {
+    let mut f = Frame::new(r, size);
+    f.fill_rectangle(Point::ORIGIN, size, BG);
+    dots(&mut f, size, step, phase);
+    f.into_geometry()
+}
+fn phase(r: &Renderer, cache: &Cache, size: Size, step: f32, builds: &Cell<usize>) -> Geometry {
+    cache.draw_with_bounds(
+        r,
+        Rectangle {
+            x: -1.,
+            y: -1.,
+            width: size.width + step + 2.,
+            height: size.height + step + 2.,
+        },
+        |f| {
+            builds.set(builds.get() + 1);
+            dots(f, size, step, Vector::ZERO);
+        },
+    )
+}
+fn submit(r: &mut Renderer, size: Size, g: Geometry, pan: Vector) {
+    r.with_layer(Rectangle::with_size(size), |r| {
+        r.with_translation(pan, |r| r.draw_geometry(g))
+    });
+}
+fn shot(r: &mut Renderer, size: Size, scale: f32) -> Vec<u8> {
+    Headless::screenshot(
+        r,
+        Size::new(
+            (size.width * scale).ceil() as u32,
+            (size.height * scale).ceil() as u32,
+        ),
+        scale,
+        BG,
+    )
+}
+fn main() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut r = rt
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .unwrap();
+    println!(
+        "renderer={}; phase-cache prototype; NOT native FPS",
+        r.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+        (Size::new(301.5, 211.25), 0.73),
+    ] {
+        let step = (24f32 * zoom).max(14.);
+        let cache = Cache::new();
+        let builds = Cell::new(0);
+        println!(
+            "size={}x{} zoom={zoom} step={step}",
+            size.width, size.height
+        );
+        for scale in [1., 1.25, 2.] {
+            for pan in [
+                Vector::ZERO,
+                Vector::new(-13.25, 9.75),
+                Vector::new(6.125, -8.5),
+                Vector::new(step - 0.125, step - 0.25),
+                Vector::new(-0.125, 0.125),
+            ] {
+                let offset = Vector::new(pan.x.rem_euclid(step), pan.y.rem_euclid(step));
+                r.reset(Rectangle::with_size(size));
+                let g = old(&r, size, step, offset);
+                r.draw_geometry(g);
+                let expected = shot(&mut r, size, scale);
+                r.reset(Rectangle::with_size(size));
+                let g = phase(&r, &cache, size, step, &builds);
+                submit(&mut r, size, g, offset);
+                let actual = shot(&mut r, size, scale);
+                assert_eq!(expected.len(), actual.len());
+                let changed = expected
+                    .chunks_exact(4)
+                    .zip(actual.chunks_exact(4))
+                    .filter(|(a, b)| a != b)
+                    .count();
+                let max = expected
+                    .iter()
+                    .zip(&actual)
+                    .map(|(a, b)| a.abs_diff(*b))
+                    .max()
+                    .unwrap_or(0);
+                println!(
+                    "scale={scale} pan={},{} changed_pixels={changed} max_channel_delta={max}",
+                    pan.x, pan.y
+                );
+            }
+        }
+        assert_eq!(builds.get(), 1);
+        for cached in [false, true] {
+            let mut ms = Vec::new();
+            for i in 0..23 {
+                r.reset(Rectangle::with_size(size));
+                let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                let now = Instant::now();
+                let g = if cached {
+                    phase(&r, &cache, size, step, &builds)
+                } else {
+                    old(&r, size, step, offset)
+                };
+                if cached {
+                    submit(&mut r, size, g, offset)
+                } else {
+                    r.draw_geometry(g)
+                };
+                let elapsed = black_box(now.elapsed().as_secs_f64() * 1000.);
+                if i >= 3 {
+                    ms.push(elapsed);
+                }
+            }
+            ms.sort_by(f64::total_cmp);
+            println!(
+                "cached={cached} construct_and_submit changing_pan n=20 p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+                ms[10], ms[19], ms[19]
+            );
+        }
+        println!("cache_builds={}", builds.get());
+        assert_eq!(builds.get(), 1);
+    }
+}

harness/experiments/grid-cache-20260925/phase_grid_replay.rs

@@ -0,0 +1,285 @@
+//! Full-sequence opaque phase replay with diagnostics and repeat controls; not application code.
+use iced::advanced::{Renderer as _, graphics::geometry::Renderer as _, renderer::Headless};
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+fn dots(f: &mut Frame, size: Size, step: f32, phase: Vector) {
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            f.fill(
+                &Path::circle(
+                    Point::new(phase.x + x as f32 * step, phase.y + y as f32 * step),
+                    0.65,
+                ),
+                DOT,
+            );
+        }
+    }
+}
+fn old(r: &Renderer, size: Size, step: f32, phase: Vector) -> Geometry {
+    let mut f = Frame::new(r, size);
+    f.fill_rectangle(Point::ORIGIN, size, BG);
+    dots(&mut f, size, step, phase);
+    f.into_geometry()
+}
+fn phase(r: &Renderer, cache: &Cache, size: Size, step: f32, builds: &Cell<usize>) -> Geometry {
+    cache.draw_with_bounds(
+        r,
+        Rectangle {
+            x: -step,
+            y: -step,
+            width: size.width + 3. * step,
+            height: size.height + 3. * step,
+        },
+        |f| {
+            builds.set(builds.get() + 1);
+            f.fill_rectangle(
+                Point::new(-step, -step),
+                Size::new(size.width + 3. * step, size.height + 3. * step),
+                BG,
+            );
+            dots(f, size, step, Vector::ZERO);
+        },
+    )
+}
+fn submit(r: &mut Renderer, size: Size, g: Geometry, pan: Vector) {
+    r.with_layer(Rectangle::with_size(size), |r| {
+        r.with_translation(pan, |r| r.draw_geometry(g))
+    });
+}
+fn shot(r: &mut Renderer, size: Size, scale: f32) -> Vec<u8> {
+    Headless::screenshot(
+        r,
+        Size::new(
+            (size.width * scale).ceil() as u32,
+            (size.height * scale).ceil() as u32,
+        ),
+        scale,
+        BG,
+    )
+}
+// Diagnostics only: this performs no rendering and does not mutate the renderer.
+fn log_coordinates(expected: &[u8], actual: &[u8], size: Size, scale: f32) {
+    assert_eq!(expected.len(), actual.len());
+    let physical_width = (size.width * scale).ceil() as usize;
+    for (index, (a, b)) in expected
+        .as_chunks::<4>()
+        .0
+        .iter()
+        .zip(actual.as_chunks::<4>().0)
+        .enumerate()
+        .filter(|(_, (a, b))| a != b)
+        .take(20)
+    {
+        println!(
+            "difference_xy={},{} expected={a:?} actual={b:?}",
+            index % physical_width,
+            index / physical_width
+        );
+    }
+}
+
+fn report_control(label: &str, expected: &[u8], actual: &[u8], size: Size, scale: f32) {
+    assert_eq!(expected.len(), actual.len());
+    let changed = expected
+        .as_chunks::<4>()
+        .0
+        .iter()
+        .zip(actual.as_chunks::<4>().0)
+        .filter(|(a, b)| a != b)
+        .count();
+    let max = expected
+        .iter()
+        .zip(actual)
+        .map(|(a, b)| a.abs_diff(*b))
+        .max()
+        .unwrap_or(0);
+    println!(
+        "comparison={label} size={}x{} scale={scale} pan=-13.25,9.75 changed_pixels={changed} max_channel_delta={max}",
+        size.width, size.height
+    );
+    log_coordinates(expected, actual, size, scale);
+}
+fn main() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut r = rt
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .unwrap();
+    println!(
+        "renderer={}; phase-cache prototype; NOT native FPS",
+        r.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+        (Size::new(301.5, 211.25), 0.73),
+    ] {
+        let step = (24f32 * zoom).max(14.);
+        let cache = Cache::new();
+        let builds = Cell::new(0);
+        println!(
+            "size={}x{} zoom={zoom} step={step}",
+            size.width, size.height
+        );
+        for scale in [1., 1.25, 2.] {
+            for pan in [
+                Vector::ZERO,
+                Vector::new(-13.25, 9.75),
+                Vector::new(6.125, -8.5),
+                Vector::new(step - 0.125, step - 0.25),
+                Vector::new(-0.125, 0.125),
+            ] {
+                let offset = Vector::new(pan.x.rem_euclid(step), pan.y.rem_euclid(step));
+                r.reset(Rectangle::with_size(size));
+                let g = old(&r, size, step, offset);
+                r.draw_geometry(g);
+                let expected = shot(&mut r, size, scale);
+                r.reset(Rectangle::with_size(size));
+                let g = phase(&r, &cache, size, step, &builds);
+                submit(&mut r, size, g, offset);
+                let actual = shot(&mut r, size, scale);
+                assert_eq!(expected.len(), actual.len());
+                let changed = expected
+                    .chunks_exact(4)
+                    .zip(actual.chunks_exact(4))
+                    .filter(|(a, b)| a != b)
+                    .count();
+                let max = expected
+                    .iter()
+                    .zip(&actual)
+                    .map(|(a, b)| a.abs_diff(*b))
+                    .max()
+                    .unwrap_or(0);
+                println!(
+                    "scale={scale} pan={},{} changed_pixels={changed} max_channel_delta={max}",
+                    pan.x, pan.y
+                );
+                // Keep the original render/timing sequence; print diagnostics only.
+                log_coordinates(&expected, &actual, size, scale);
+            }
+        }
+        assert_eq!(builds.get(), 1);
+        for cached in [false, true] {
+            let mut ms = Vec::new();
+            for i in 0..23 {
+                r.reset(Rectangle::with_size(size));
+                let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                let now = Instant::now();
+                let g = if cached {
+                    phase(&r, &cache, size, step, &builds)
+                } else {
+                    old(&r, size, step, offset)
+                };
+                if cached {
+                    submit(&mut r, size, g, offset)
+                } else {
+                    r.draw_geometry(g)
+                };
+                let elapsed = black_box(now.elapsed().as_secs_f64() * 1000.);
+                if i >= 3 {
+                    ms.push(elapsed);
+                }
+            }
+            ms.sort_by(f64::total_cmp);
+            println!(
+                "cached={cached} construct_and_submit changing_pan n=20 p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+                ms[10], ms[19], ms[19]
+            );
+        }
+        println!("cache_builds={}", builds.get());
+        assert_eq!(builds.get(), 1);
+        // Includes backend prepare/upload and readback; still not native presentation.
+        if size.width == 1900. && zoom == 1. || size.width == 1440. && zoom == 0.5 {
+            for cached in [false, true] {
+                let mut ms = Vec::new();
+                for i in 0..10 {
+                    r.reset(Rectangle::with_size(size));
+                    let offset = Vector::new((i as f32 * 0.25).rem_euclid(step), 9.75);
+                    let now = Instant::now();
+                    let g = if cached {
+                        phase(&r, &cache, size, step, &builds)
+                    } else {
+                        old(&r, size, step, offset)
+                    };
+                    if cached {
+                        submit(&mut r, size, g, offset);
+                    } else {
+                        r.draw_geometry(g);
+                    }
+                    let pixels = black_box(shot(&mut r, size, 1.));
+                    let elapsed = now.elapsed().as_secs_f64() * 1000.;
+                    drop(pixels);
+                    if i >= 2 {
+                        ms.push(elapsed);
+                    }
+                }
+                ms.sort_by(f64::total_cmp);
+                println!(
+                    "cached={cached} construct_submit_screenshot changing_pan n=8 p50_ms={:.4} min_ms={:.4} max_ms={:.4}",
+                    ms[4], ms[0], ms[7]
+                );
+            }
+        }
+    }
+    // All original cases, timings and screenshots have completed above.
+    // Reuse the same renderer for controls. This cache is newly constructed,
+    // then retained across all control repetitions; original per-case caches
+    // have already gone out of scope, exactly as in the opaque probe.
+    println!("original_sequence_complete; beginning same-renderer repeat controls");
+    let size = Size::new(301.5, 211.25);
+    let step = (24f32 * 0.73).max(14.);
+    let pan: Vector<f32> = Vector::new(-13.25, 9.75);
+    let offset = Vector::new(pan.x.rem_euclid(step), pan.y.rem_euclid(step));
+    let cache = Cache::new();
+    let builds = Cell::new(0);
+    for repetition in 1..=3 {
+        for scale in [1., 2.] {
+            r.reset(Rectangle::with_size(size));
+            let g = old(&r, size, step, offset);
+            r.draw_geometry(g);
+            let first = shot(&mut r, size, scale);
+            r.reset(Rectangle::with_size(size));
+            let g = old(&r, size, step, offset);
+            r.draw_geometry(g);
+            let second = shot(&mut r, size, scale);
+            report_control(
+                &format!("old/old repetition={repetition}"),
+                &first,
+                &second,
+                size,
+                scale,
+            );
+
+            r.reset(Rectangle::with_size(size));
+            let g = phase(&r, &cache, size, step, &builds);
+            submit(&mut r, size, g, offset);
+            let first = shot(&mut r, size, scale);
+            r.reset(Rectangle::with_size(size));
+            let g = phase(&r, &cache, size, step, &builds);
+            submit(&mut r, size, g, offset);
+            let second = shot(&mut r, size, scale);
+            report_control(
+                &format!("cached/cached repetition={repetition}"),
+                &first,
+                &second,
+                size,
+                scale,
+            );
+        }
+    }
+    println!("control_cache_builds={}", builds.get());
+    assert_eq!(builds.get(), 1);
+}

harness/experiments/grid-cache-20260925/production_grid_probe.rs

@@ -0,0 +1,184 @@
+//! Headless rendering experiment; creates no desktop window and sends no input.
+use iced::advanced::{
+    graphics::geometry::Renderer as _,
+    renderer::{Headless, Renderer as _},
+};
+use iced::widget::canvas;
+use iced::{
+    Color, Point, Rectangle, Renderer, Size, Vector,
+    widget::canvas::{Cache, Frame, Geometry, Path},
+};
+use std::{cell::Cell, hint::black_box, time::Instant};
+
+// Compile the actual candidate cache, not a second implementation of its key.
+#[path = "../../../crates/oa-desktop/src/diagram/grid.rs"]
+mod grid;
+mod style {
+    pub const LINE: iced::Color = iced::Color::from_rgb(0.86, 0.89, 0.91);
+}
+
+const BG: Color = Color::from_rgb8(246, 248, 251);
+const DOT: Color = Color::from_rgb(0.86, 0.89, 0.91);
+
+fn paint(frame: &mut Frame, size: Size, zoom: f32, pan: Vector) {
+    frame.fill_rectangle(Point::ORIGIN, size, BG);
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    for x in 0..(size.width / step) as i32 + 1 {
+        for y in 0..(size.height / step) as i32 + 1 {
+            frame.fill(
+                &Path::circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65),
+                DOT,
+            );
+        }
+    }
+}
+fn fresh(renderer: &Renderer, size: Size, zoom: f32, pan: Vector) -> Geometry {
+    let mut frame = Frame::new(renderer, size);
+    paint(&mut frame, size, zoom, pan);
+    frame.into_geometry()
+}
+fn batched(renderer: &Renderer, size: Size, zoom: f32, pan: Vector) -> Geometry {
+    let mut frame = Frame::new(renderer, size);
+    frame.fill_rectangle(Point::ORIGIN, size, BG);
+    let step = (24. * zoom).max(14.);
+    let ox = pan.x.rem_euclid(step);
+    let oy = pan.y.rem_euclid(step);
+    let path = Path::new(|p| {
+        for x in 0..(size.width / step) as i32 + 1 {
+            for y in 0..(size.height / step) as i32 + 1 {
+                p.circle(Point::new(ox + x as f32 * step, oy + y as f32 * step), 0.65);
+                p.close();
+            }
+        }
+    });
+    frame.fill(&path, DOT);
+    frame.into_geometry()
+}
+fn screenshot(renderer: &mut Renderer, size: Size, geometry: Geometry) -> Vec<u8> {
+    renderer.reset(Rectangle::with_size(size));
+    renderer.draw_geometry(geometry);
+    Headless::screenshot(
+        renderer,
+        Size::new(size.width as u32, size.height as u32),
+        1.,
+        BG,
+    )
+}
+fn measure<T>(label: &str, n: usize, mut f: impl FnMut() -> T) {
+    for _ in 0..3 {
+        black_box(f());
+    }
+    let mut values = Vec::new();
+    for _ in 0..n {
+        let now = Instant::now();
+        let value = black_box(f());
+        values.push(now.elapsed().as_secs_f64() * 1000.);
+        drop(value);
+    }
+    values.sort_by(f64::total_cmp);
+    let at = |p: f64| values[((n - 1) as f64 * p).ceil() as usize];
+    println!(
+        "{label}: n={n} p50_ms={:.4} p95_ms={:.4} max_ms={:.4}",
+        at(0.5),
+        at(0.95),
+        values[n - 1]
+    );
+}
+fn main() {
+    let n = std::env::args()
+        .nth(1)
+        .map(|s| s.parse::<usize>().unwrap())
+        .unwrap_or(20)
+        .max(1);
+    let runtime = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap();
+    let mut renderer = runtime
+        .block_on(<Renderer as Headless>::new(
+            iced::Font::DEFAULT,
+            16.into(),
+            None,
+        ))
+        .expect("headless production renderer");
+    println!(
+        "renderer={} samples={n}; screenshot includes offscreen rendering + GPU readback, NOT native frame presentation",
+        renderer.name()
+    );
+    for (size, zoom) in [
+        (Size::new(1900., 660.), 1.),
+        (Size::new(1900., 660.), 0.5),
+        (Size::new(1440., 900.), 1.),
+        (Size::new(1440., 900.), 0.5),
+    ] {
+        let pan = Vector::new(-13.25, 9.75);
+        let cache = Cache::new();
+        let calls = Cell::new(0);
+        let cached = |r: &Renderer| {
+            cache.draw(r, size, |f| {
+                calls.set(calls.get() + 1);
+                paint(f, size, zoom, pan);
+            })
+        };
+        let step = (24f32 * zoom).max(14.);
+        println!(
+            "\nsize={}x{} zoom={zoom} dots={}",
+            size.width,
+            size.height,
+            ((size.width / step) as i32 + 1) * ((size.height / step) as i32 + 1)
+        );
+        let baseline = fresh(&renderer, size, zoom, pan);
+        let baseline_pixels = screenshot(&mut renderer, size, baseline);
+        let geometry = batched(&renderer, size, zoom, pan);
+        let pixels = screenshot(&mut renderer, size, geometry);
+        let differences = baseline_pixels
+            .iter()
+            .zip(&pixels)
+            .filter(|(a, b)| a != b)
+            .count();
+        println!("batched_rgba_byte_differences={differences}");
+        assert_eq!(
+            differences, 0,
+            "batched path must preserve exact grid pixels"
+        );
+        let geometry = cached(&renderer);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, geometry));
+        let geometry = cached(&renderer);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, geometry));
+        assert_eq!(calls.get(), 1);
+        println!("pixel_parity=cold_and_warm_exact");
+        measure("fresh_geometry", n, || fresh(&renderer, size, zoom, pan));
+        let production = grid::Grid::default();
+        let g = production.draw(&renderer, size, zoom, pan);
+        assert_eq!(baseline_pixels, screenshot(&mut renderer, size, g));
+        measure("production_cached_geometry", n, || {
+            production.draw(&renderer, size, zoom, pan)
+        });
+        let mut tick = 0;
+        measure("production_changing_pan_geometry", n, || {
+            tick += 1;
+            production.draw(
+                &renderer,
+                size,
+                zoom,
+                pan + Vector::new(tick as f32 * 0.25, 0.),
+            )
+        });
+        measure("cached_geometry", n, || cached(&renderer));
+        assert_eq!(calls.get(), 1, "identical camera must reuse geometry");
+        measure("fresh_geometry_and_screenshot", n, || {
+            let g = fresh(&renderer, size, zoom, pan);
+            screenshot(&mut renderer, size, g)
+        });
+        measure("cached_geometry_and_screenshot", n, || {
+            let g = cached(&renderer);
+            screenshot(&mut renderer, size, g)
+        });
+        measure("cache_forced_miss_geometry", n, || {
+            cache.clear();
+            cached(&renderer)
+        });
+    }
+}

harness/prerelease-integrated-source-20260924.md

@@ -80,6 +80,30 @@ actionable defect in the stated boundary. These do not substitute for the final
 combined execution. The vendor patch-description correction is incorporated at
 `17eaa03fd69741dff746f21d150dc04c341411b3`.
 
+## Mounted State picker correction
+
+The combined Windows test run at `8ddfadf440b5c208b1adb6b211a97ba0c99cff04`
+failed the mounted State missing-picker Escape regression. The test located the
+picker relative to the canvas, but the integrated selection toolbar adds 56px
+plus an 8px gap between them. Both the opening and option clicks were stale.
+Parent and independent source inspection agreed on this fixture defect; they
+found no reason to change the production Escape policy from this failure.
+
+Successor `a9cd364eacbbffa0693bab05b5a2b65f9d105535` adds a zero-padding
+identified container around the existing fixed-height picker slot. The fixture
+measures that slot, checks Escape capture before App subscriptions, and retains
+zero messages, exact document/source/selection/camera/revision/history,
+reopen-and-Place, and exact source Undo checks. The option coordinate assumes
+this fixture's single downward-opening menu at 1800 by 1100; it is not a general
+overlay geometry evaluator. No production Escape handler changes.
+
+The peer records 2,199 passes, one failure and eight ignores for that failed
+full run, with lint and product builds not run. The earlier final-02 attempt
+was interrupted during harness listing before test bodies; neither attempt is
+a passed gate. [Preserved attempts and v2 recipe](http://217.177.34.108:3000/sorokin.oleg.edu/ARCADIA-Studio/src/commit/184c1307d1ae3d49007480020fa1c080c94ececa/harness/prerelease37-windows-gates-20260924/attempts-8dd)
+retain their distinct boundaries. The corrected source requires current
+combined Windows gates and packaged native acceptance.
+
 ## Combined gates and package handoff
 
 The first peer compilation exposed E0425 in the new Route fixture: its