Panics · P32 Canvas: panels take their handlers in new; stale nodes, shapes, layers and topics change nothing

AGENTS.md

@@ -204,7 +204,7 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - A box that shows a host's picture takes the picture's shape from the host (`ratio`), so nothing is cropped and a point given as a share lands on the picture. A focusable one keeps its focus border on an outer box, so the picture keeps that shape exactly (`media::ImageCropper`).
 - A default only the component can work out, such as a crop fitted to a picture it decodes, reaches the owner once through `window.defer` after render (`media::ImageUpload`).
 - A ScrubInput shows its number in about 140px beside a short label. In a narrower column a pair hides it, so a long label takes a row of its own (`canvas::TypographyPanel`).
-- Design panels edit a whole value and hand the owner a changed copy through `canvas::panel::editing`, which takes the owner's handler itself: a component without one fails at render. A swatch that opens a picker is `canvas::panel::color_well`.
+- Design panels edit a whole value and hand the owner a changed copy through `canvas::panel::editing`; the owner's handler is an argument of `new`. A swatch that opens a picker is `canvas::panel::color_well`.
 - A press that stops propagation also stops the ancestors' focus on press. A layer that takes keys focuses itself in its own press handler (`canvas::ToolLayer`, `canvas::MindMap`), and a field over it stops its own presses.
 - A button inside a pressable row goes through `lists::row_action`, which keeps its press and its Space or Enter from the row (`devtools::ConnectionManager`).
 - A field opened over a component hands focus back to that component on Enter and Escape, through `forms::Editing`'s `returning` and `give_back` (`canvas::writing`); a blur keeps the words and leaves focus where it went.

examples/gallery/pages/canvas/boards.rs

@@ -221,18 +221,26 @@ pub fn mind(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                 change(&added, cx, |mind| {
                     mind.made += 1;
                     let key = SharedString::from(format!("idea-{}", mind.made));
-                    mind.root = mind.root.adding(parent, Topic::new(key.clone(), "New idea"));
-                    mind.selected = Some(key);
+                    if let Some(root) = mind.root.adding(parent, Topic::new(key.clone(), "New idea")) {
+                        mind.root = root;
+                        mind.selected = Some(key);
+                    }
                 })
             })
             .on_remove(move |key, _, cx| {
                 change(&removed, cx, |mind| {
-                    mind.selected = mind.root.parent_of(key);
-                    mind.root = mind.root.removing(key);
+                    if let Some(root) = mind.root.removing(key) {
+                        mind.selected = mind.root.parent_of(key);
+                        mind.root = root;
+                    }
                 })
             })
             .on_rename(move |key, text, _, cx| {
-                change(&renamed, cx, |mind| mind.root = mind.root.renaming(key, text.clone()))
+                change(&renamed, cx, |mind| {
+                    if let Some(root) = mind.root.renaming(key, text.clone()) {
+                        mind.root = root;
+                    }
+                })
             })
             .on_viewport(move |next, _, cx| change(&viewed, cx, |mind| mind.view = next)),
         cx,

examples/gallery/pages/canvas/looks.rs

@@ -121,9 +121,8 @@ pub fn styles(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
             .gap_6()
             .child(
                 div().w(px(260.)).child(
-                    ColorPanel::new("canvas-color", color)
-                        .swatches(SWATCHES.map(|(name, hex)| (name, Hsla::from(rgb(hex)))))
-                        .on_change(move |next, _, cx| change(&colored, cx, |look| look.color = next)),
+                    ColorPanel::new("canvas-color", color, move |next, _, cx| change(&colored, cx, |look| look.color = next))
+                        .swatches(SWATCHES.map(|(name, hex)| (name, Hsla::from(rgb(hex))))),
                 ),
             )
             .child(
@@ -137,8 +136,7 @@ pub fn styles(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                             .on_change(move |next, _, cx| change(&graded, cx, |look| look.stops = next.to_vec())),
                     )
                     .child(
-                        ShadowEditor::new("canvas-shadows", shadows)
-                            .on_change(move |next, _, cx| change(&shaded, cx, |look| look.shadows = next)),
+                        ShadowEditor::new("canvas-shadows", shadows, move |next, _, cx| change(&shaded, cx, |look| look.shadows = next)),
                     ),
             )
             .child(
@@ -148,15 +146,13 @@ pub fn styles(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                     .flex_col()
                     .gap_6()
                     .child(
-                        BorderEditor::new("canvas-border", border)
-                            .on_change(move |next, _, cx| change(&bordered, cx, |look| look.border = next)),
+                        BorderEditor::new("canvas-border", border, move |next, _, cx| change(&bordered, cx, |look| look.border = next)),
                     )
                     .child(div().p_6().child(card)),
             )
             .child(
                 div().w(px(280.)).child(
-                    TypographyPanel::new("canvas-type", style, &search)
-                        .on_change(move |next, _, cx| change(&typed, cx, |look| look.style = next)),
+                    TypographyPanel::new("canvas-type", style, &search, move |next, _, cx| change(&typed, cx, |look| look.style = next)),
                 ),
             ),
     )
@@ -282,8 +278,7 @@ pub fn rules(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                     .flex_col()
                     .gap_3()
                     .child(
-                        ConstraintsEditor::new("canvas-constraints", constraints)
-                            .on_change(move |next, _, cx| change(&pinned, cx, |rules| rules.constraints = next)),
+                        ConstraintsEditor::new("canvas-constraints", constraints, move |next, _, cx| change(&pinned, cx, |rules| rules.constraints = next)),
                     )
                     .child(pinned_preview),
             )
@@ -294,8 +289,7 @@ pub fn rules(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                     .flex_col()
                     .gap_3()
                     .child(
-                        AutoLayoutControls::new("canvas-auto-layout", layout)
-                            .on_change(move |next, _, cx| change(&laid, cx, |rules| rules.layout = next)),
+                        AutoLayoutControls::new("canvas-auto-layout", layout, move |next, _, cx| change(&laid, cx, |rules| rules.layout = next)),
                     )
                     .child(laid_preview),
             )
@@ -306,9 +300,7 @@ pub fn rules(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                     .flex_col()
                     .gap_3()
                     .child(
-                        ExportPanel::new("canvas-export", "Card", exports)
-                            .on_change(move |next, _, cx| change(&set, cx, |rules| rules.exports = next))
-                            .on_export(move |files, _, cx| change(&sent, cx, |rules| rules.exported = files)),
+                        ExportPanel::new("canvas-export", "Card", exports, move |next, _, cx| change(&set, cx, |rules| rules.exports = next), move |files, _, cx| change(&sent, cx, |rules| rules.exported = files)),
                     )
                     .when(!exported.is_empty(), |panel| {
                         panel.child(note(format!("Exported {}", exported.join(", ")).into()))

examples/gallery/pages/canvas/panels.rs

@@ -134,19 +134,18 @@ pub fn arrange(window: &mut Window, cx: &mut App) -> impl IntoElement + use<> {
                 studio.record(align.words().into());
             })
         });
-    let inspector =
-        InspectorPanel::new("canvas-inspector", chosen).on_change(move |shape, _, cx| {
-            change(&edited, cx, |studio| {
-                let at = studio
-                    .shapes
-                    .iter()
-                    .position(|each| each.key == shape.key)
-                    .expect("a listed shape");
-                let words = format!("Edit {}", shape.name);
-                studio.shapes[at] = shape;
-                studio.record(words);
-            })
-        });
+    let inspector = InspectorPanel::new("canvas-inspector", chosen, move |shape, _, cx| {
+        change(&edited, cx, |studio| {
+            let at = studio
+                .shapes
+                .iter()
+                .position(|each| each.key == shape.key)
+                .expect("a listed shape");
+            let words = format!("Edit {}", shape.name);
+            studio.shapes[at] = shape;
+            studio.record(words);
+        })
+    });
     let assets = AssetPanel::new("canvas-assets")
         .group("Shapes", shapes())
         .group("Notes", notes())

src/canvas/autolayout.rs

@@ -104,32 +104,26 @@ impl AutoLayout {
 pub struct AutoLayoutControls {
     id: ElementId,
     layout: AutoLayout,
-    on_change: Option<OnEdit<AutoLayout>>,
+    on_change: OnEdit<AutoLayout>,
 }
 
 impl AutoLayoutControls {
-    pub fn new(id: impl Into<ElementId>, layout: AutoLayout) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        layout: AutoLayout,
+        on_change: impl Fn(AutoLayout, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             layout,
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
-
-    pub fn on_change(
-        mut self,
-        handler: impl Fn(AutoLayout, &mut Window, &mut App) + 'static,
-    ) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 impl RenderOnce for AutoLayoutControls {
     fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("auto layout controls {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let (id, layout, on_change) = (self.id, self.layout, &on_change);
         let place = Rc::new(editing(
             "auto layout",

src/canvas/constraints.rs

@@ -102,25 +102,21 @@ impl Constraints {
 pub struct ConstraintsEditor {
     id: ElementId,
     constraints: Constraints,
-    on_change: Option<OnEdit<Constraints>>,
+    on_change: OnEdit<Constraints>,
 }
 
 impl ConstraintsEditor {
-    pub fn new(id: impl Into<ElementId>, constraints: Constraints) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        constraints: Constraints,
+        on_change: impl Fn(Constraints, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             constraints,
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
-
-    pub fn on_change(
-        mut self,
-        handler: impl Fn(Constraints, &mut Window, &mut App) + 'static,
-    ) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 /// A hairline from `x`, `y` in shares of its box, `len` long across or down.
@@ -135,9 +131,7 @@ fn hairline(x: f32, y: f32, len: f32, across: bool, color: Hsla) -> gpui::Div {
 
 impl RenderOnce for ConstraintsEditor {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("constraints editor {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let (id, now, on_change) = (self.id, self.constraints, &on_change);
         let theme = cx.theme();
         let (lit, rest) = (theme.colors.accent, theme.colors.border);

src/canvas/export.rs

@@ -99,8 +99,8 @@ pub struct ExportPanel {
     id: ElementId,
     name: SharedString,
     settings: Vec<ExportSetting>,
-    on_change: Option<OnEdit<Vec<ExportSetting>>>,
-    on_export: Option<OnEdit<Vec<String>>>,
+    on_change: OnEdit<Vec<ExportSetting>>,
+    on_export: OnEdit<Vec<String>>,
 }
 
 impl ExportPanel {
@@ -109,41 +109,23 @@ impl ExportPanel {
         id: impl Into<ElementId>,
         name: impl Into<SharedString>,
         settings: impl IntoIterator<Item = ExportSetting>,
+        on_change: impl Fn(Vec<ExportSetting>, &mut Window, &mut App) + 'static,
+        on_export: impl Fn(Vec<String>, &mut Window, &mut App) + 'static,
     ) -> Self {
         Self {
             id: id.into(),
             name: name.into(),
             settings: settings.into_iter().collect(),
-            on_change: None,
-            on_export: None,
+            on_change: Rc::new(on_change),
+            on_export: Rc::new(on_export),
         }
     }
-
-    pub fn on_change(
-        mut self,
-        handler: impl Fn(Vec<ExportSetting>, &mut Window, &mut App) + 'static,
-    ) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
-
-    pub fn on_export(
-        mut self,
-        handler: impl Fn(Vec<String>, &mut Window, &mut App) + 'static,
-    ) -> Self {
-        self.on_export = Some(Rc::new(handler));
-        self
-    }
 }
 
 impl RenderOnce for ExportPanel {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("export panel {:?} has no on_change", self.id));
-        let on_export = self
-            .on_export
-            .unwrap_or_else(|| panic!("export panel {:?} has no on_export", self.id));
+        let on_change = self.on_change;
+        let on_export = self.on_export;
         let (id, settings, on_change) = (self.id, self.settings, &on_change);
         let files = export_files(&self.name, &settings);
         let next = added(&settings);

src/canvas/gesture.rs

@@ -168,12 +168,11 @@ pub(super) fn commit(
             from,
             to,
         } => {
-            let frame = scene
-                .shapes
-                .iter()
-                .find(|shape| shape.key == key)
-                .expect("the resized shape is listed")
-                .frame;
+            let Some(shape) = scene.shapes.iter().find(|shape| shape.key == key) else {
+                log::error!("tool layer: resized shape {key} left the canvas");
+                return;
+            };
+            let frame = shape.frame;
             let next = resized(frame, handle, (to.0 - from.0, to.1 - from.1), LEAST, square);
             log::info!("tool layer: resize {key} to {next:?}");
             if let Some(on_resize) = &handlers.on_resize {
@@ -191,6 +190,10 @@ pub(super) fn commit(
             }
         }
         Gesture::Linking { from, to } => {
+            if !scene.shapes.iter().any(|shape| shape.key == from) {
+                log::error!("tool layer: the link's shape {from} left the canvas");
+                return;
+            }
             let Some(ix) = hit(&scene.shapes, to, REACH / scene.view.zoom) else {
                 log::info!("tool layer: the link from {from} lands on nothing");
                 return;

src/canvas/graph.rs

@@ -70,18 +70,9 @@ impl Node {
         (x, self.at.1 + HEAD + ROW * row as f32 + ROW / 2.0)
     }
 
-    fn row(&self, out: bool, port: &str) -> usize {
+    fn row(&self, out: bool, port: &str) -> Option<usize> {
         let ports = if out { &self.outputs } else { &self.inputs };
-        ports
-            .iter()
-            .position(|each| each.key == port)
-            .unwrap_or_else(|| {
-                panic!(
-                    "node {} has no {} {port}",
-                    self.key,
-                    if out { "output" } else { "input" }
-                )
-            })
+        ports.iter().position(|each| each.key == port)
     }
 }
 
@@ -119,22 +110,26 @@ pub(crate) struct Socket {
     pub kind: SharedString,
 }
 
-fn node<'a>(nodes: &'a [Node], key: &str) -> &'a Node {
-    nodes
-        .iter()
-        .find(|node| node.key == key)
-        .unwrap_or_else(|| panic!("no node {key} in the graph"))
-}
+/// Where a wire starts and ends in canvas units, and the kind it carries.
+pub(crate) type Ends = ((f32, f32), (f32, f32), SharedString);
 
-/// An edge's ends in canvas units and the kind it carries.
-pub(crate) fn ends(nodes: &[Node], edge: &Edge) -> ((f32, f32), (f32, f32), SharedString) {
-    let (from, to) = (node(nodes, &edge.from.0), node(nodes, &edge.to.0));
-    let row = from.row(true, &edge.from.1);
-    (
-        from.socket(true, row),
-        to.socket(false, to.row(false, &edge.to.1)),
-        from.outputs[row].kind.clone(),
-    )
+/// An edge's ends; none when a node or port it names left the graph.
+pub(crate) fn ends(nodes: &[Node], edge: &Edge) -> Option<Ends> {
+    let node = |key: &SharedString| nodes.iter().find(|node| node.key == *key);
+    let ends = node(&edge.from.0)
+        .zip(node(&edge.to.0))
+        .and_then(|(from, to)| {
+            let (out, input) = (from.row(true, &edge.from.1)?, to.row(false, &edge.to.1)?);
+            Some((
+                from.socket(true, out),
+                to.socket(false, input),
+                from.outputs[out].kind.clone(),
+            ))
+        });
+    if ends.is_none() {
+        log::error!("node editor: edge {edge:?} names a node or port gone from the graph");
+    }
+    ends
 }
 
 /// The socket within `reach` of `point`, the topmost node first.
@@ -199,7 +194,8 @@ mod tests {
     #[test]
     fn sockets_sit_on_the_sides_a_row_apart() {
         let nodes = graph();
-        let (from, to, kind) = ends(&nodes, &Edge::new(("load", "image"), ("blur", "image")));
+        let (from, to, kind) =
+            ends(&nodes, &Edge::new(("load", "image"), ("blur", "image"))).expect("both ends");
         assert_eq!(from, (WIDE, HEAD + ROW / 2.0));
         assert_eq!(to, (300.0, HEAD + ROW / 2.0));
         assert_eq!(kind, "image");
@@ -210,6 +206,14 @@ mod tests {
             ("blur", "radius", false)
         );
         assert_eq!(socket_at(&nodes, (150.0, 40.0), 6.0), None);
+        assert_eq!(
+            ends(&nodes, &Edge::new(("load", "image"), ("gone", "image"))),
+            None
+        );
+        assert_eq!(
+            ends(&nodes, &Edge::new(("load", "gone"), ("blur", "image"))),
+            None
+        );
     }
 
     #[test]

src/canvas/history.rs

@@ -27,11 +27,12 @@ impl HistoryPanel {
         at: usize,
     ) -> Self {
         let steps: Vec<SharedString> = steps.into_iter().map(Into::into).collect();
-        assert!(
-            at <= steps.len(),
-            "history at {at} of {} steps",
-            steps.len()
-        );
+        if at > steps.len() {
+            log::error!(
+                "history panel: at {at} of {} steps; none current",
+                steps.len()
+            );
+        }
         Self {
             id: id.into(),
             steps,

src/canvas/inspector.rs

@@ -25,29 +25,26 @@ const REACH: f64 = 100_000.0;
 pub struct InspectorPanel {
     id: ElementId,
     selection: Vec<Shape>,
-    on_change: Option<OnEdit<Shape>>,
+    on_change: OnEdit<Shape>,
 }
 
 impl InspectorPanel {
-    pub fn new(id: impl Into<ElementId>, selection: impl IntoIterator<Item = Shape>) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        selection: impl IntoIterator<Item = Shape>,
+        on_change: impl Fn(Shape, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             selection: selection.into_iter().collect(),
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
-
-    pub fn on_change(mut self, handler: impl Fn(Shape, &mut Window, &mut App) + 'static) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 impl RenderOnce for InspectorPanel {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("inspector panel {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let id = self.id;
         let [shape] = self.selection.as_slice() else {
             let title: SharedString = match self.selection.len() {

src/canvas/layers.rs

@@ -8,30 +8,30 @@ use super::{
 };
 use crate::lists::{DropAt, Tree, TreeNode};
 
-/// The keys in paint order, bottom first, after `dragged` lands `at` `target` in a list drawn top first.
+/// The keys in paint order, bottom first, after `dragged` lands `at` `target` in a list drawn top first; none, logged, when either left the list.
 pub(crate) fn restacked(
     order: &[SharedString],
     dragged: &SharedString,
     target: &SharedString,
     at: DropAt,
-) -> Vec<SharedString> {
-    assert!(order.contains(dragged), "layer {dragged} is not listed");
+) -> Option<Vec<SharedString>> {
     let mut rest: Vec<SharedString> = order
         .iter()
         .filter(|key| *key != dragged)
         .cloned()
         .collect();
-    let under = rest
-        .iter()
-        .position(|key| key == target)
-        .unwrap_or_else(|| panic!("layer {dragged} lands against {target}, which is not listed"));
+    let under = rest.iter().position(|key| key == target);
+    let (true, Some(under)) = (order.contains(dragged), under) else {
+        log::error!("layer panel: {dragged} or {target} left the layers; nothing moves");
+        return None;
+    };
     let ix = match at {
         DropAt::Before => under + 1,
         DropAt::After => under,
         DropAt::Inside => panic!("layer {target} holds no layers"),
     };
     rest.insert(ix, dragged.clone());
-    rest
+    Some(rest)
 }
 
 /// The canvas's layers, topmost first. A box shows or hides each, a press selects and Shift or Command adds, F2 renames, and a drag restacks; a locked layer says so. It fills its box, which the host sizes.
@@ -137,7 +137,9 @@ impl RenderOnce for LayerPanel {
         if let Some(on_restack) = self.on_restack {
             tree = tree.on_move(move |dragged, target, at, window, cx| {
                 log::info!("layer panel: {dragged} {at:?} {target}");
-                on_restack(&restacked(&order, dragged, target, at), window, cx);
+                if let Some(order) = restacked(&order, dragged, target, at) {
+                    on_restack(&order, window, cx);
+                }
             });
         }
         tree
@@ -160,15 +162,15 @@ mod tests {
         let order = keys(&["a", "b", "c"]);
         assert_eq!(
             restacked(&order, &"a".into(), &"c".into(), DropAt::Before),
-            keys(&["b", "c", "a"])
+            Some(keys(&["b", "c", "a"]))
         );
         assert_eq!(
             restacked(&order, &"c".into(), &"a".into(), DropAt::After),
-            keys(&["c", "a", "b"])
+            Some(keys(&["c", "a", "b"]))
         );
         assert_eq!(
             restacked(&order, &"a".into(), &"b".into(), DropAt::After),
-            keys(&["a", "b", "c"]),
+            Some(keys(&["a", "b", "c"])),
             "just under b is where a lies"
         );
     }

src/canvas/mindmap.rs

@@ -24,37 +24,40 @@ impl Topic {
         self
     }
 
-    /// The map with `topic` added last under `parent`.
-    pub fn adding(&self, parent: &str, topic: Topic) -> Topic {
+    /// The map with `topic` added last under `parent`; none, logged, when the map holds no `parent`.
+    pub fn adding(&self, parent: &str, topic: Topic) -> Option<Topic> {
         let mut next = self.clone();
-        let under = next
-            .find(parent)
-            .unwrap_or_else(|| panic!("no topic {parent} to add under"));
+        let Some(under) = next.find(parent) else {
+            log::error!("mind map: no topic {parent} to add under");
+            return None;
+        };
         under.children.push(topic);
-        next
+        Some(next)
     }
 
-    /// The map without `key` and what lies under it.
-    pub fn removing(&self, key: &str) -> Topic {
-        assert!(self.key != key, "the root topic {key} stays");
+    /// The map without `key` and what lies under it; none, logged, for the root or a topic the map lacks.
+    pub fn removing(&self, key: &str) -> Option<Topic> {
         let mut next = self.clone();
-        let parent = next
-            .parent_of(key)
-            .unwrap_or_else(|| panic!("no topic {key} to remove"));
+        let Some(parent) = next.parent_of(key) else {
+            log::error!("mind map: no topic {key} below the root to remove");
+            return None;
+        };
         next.find(&parent)
             .expect("the parent is in the map")
             .children
             .retain(|topic| topic.key != key);
-        next
+        Some(next)
     }
 
-    /// The map with `key` reading `text`.
-    pub fn renaming(&self, key: &str, text: impl Into<SharedString>) -> Topic {
+    /// The map with `key` reading `text`; none, logged, when the map holds no `key`.
+    pub fn renaming(&self, key: &str, text: impl Into<SharedString>) -> Option<Topic> {
         let mut next = self.clone();
-        next.find(key)
-            .unwrap_or_else(|| panic!("no topic {key} to rename"))
-            .text = text.into();
-        next
+        let Some(topic) = next.find(key) else {
+            log::error!("mind map: no topic {key} to rename");
+            return None;
+        };
+        topic.text = text.into();
+        Some(next)
     }
 
     fn find(&mut self, key: &str) -> Option<&mut Topic> {
@@ -229,10 +232,15 @@ mod tests {
     fn edits_add_remove_and_rename_by_key() {
         let map = map()
             .adding("b", Topic::new("b1", "Release"))
-            .renaming("c", "Money");
+            .and_then(|map| map.renaming("c", "Money"))
+            .expect("both topics are in the map");
         assert_eq!(map.children[1].children[0].key, "b1");
         assert_eq!(map.children[2].text, "Money");
-        let map = map.removing("a");
+        assert_eq!(map.adding("gone", Topic::new("x", "X")), None);
+        assert_eq!(map.renaming("gone", "X"), None);
+        assert_eq!(map.removing(&map.key), None, "the root stays");
+        assert_eq!(map.removing("gone"), None);
+        let map = map.removing("a").expect("a is in the map");
         assert_eq!(
             map.children
                 .iter()

src/canvas/mindmap_view.rs

@@ -117,13 +117,13 @@ impl RenderOnce for MindMap {
         let focus = tab_stop((id.clone(), "focus").into(), true, window, cx);
         let editing =
             window.use_keyed_state((id.clone(), "editing"), cx, |_, _| Editing::default());
-        let selected = self.selected.clone();
-        if let Some(key) = &selected {
-            assert!(
-                placed.iter().any(|topic| topic.key == *key),
-                "mind map {id:?}: no topic {key} to select"
-            );
-        }
+        let selected = self.selected.clone().filter(|key| {
+            let placed = placed.iter().any(|topic| topic.key == *key);
+            if !placed {
+                log::error!("mind map {id:?}: no topic {key}; none selected");
+            }
+            placed
+        });
         let rename = {
             let (editing, placed, on_rename, home) = (
                 editing.clone(),

src/canvas/nodes.rs

@@ -234,17 +234,20 @@ impl RenderOnce for NodeGraph {
                                 let wired = edges
                                     .iter()
                                     .find(|edge| edge.to == (node_key.clone(), port_key.clone()));
-                                match wired {
-                                    Some(edge) => {
-                                        let source = nodes
-                                            .iter()
-                                            .find(|node| node.key == edge.from.0)
-                                            .expect("a wired node");
-                                        let port = source
-                                            .outputs
-                                            .iter()
-                                            .find(|port| port.key == edge.from.1)
-                                            .expect("a wired port");
+                                let source = wired.and_then(|edge| {
+                                    let port = nodes
+                                        .iter()
+                                        .find(|node| node.key == edge.from.0)?
+                                        .outputs
+                                        .iter()
+                                        .find(|port| port.key == edge.from.1);
+                                    if port.is_none() {
+                                        log::error!("node editor: edge {edge:?} starts at a port gone from the graph");
+                                    }
+                                    Some(edge).zip(port)
+                                });
+                                match source {
+                                    Some((edge, port)) => {
                                         Pull::Wiring {
                                             from: Socket {
                                                 node: edge.from.0.clone(),
@@ -330,16 +333,26 @@ impl RenderOnce for NodeGraph {
             let (nodes, edges, hue) = (nodes.clone(), edges.clone(), hue.clone());
             let pending = match &pull {
                 Pull::Wiring { from, to, .. } => {
-                    let source = nodes
-                        .iter()
-                        .find(|node| node.key == from.node)
-                        .expect("a wiring node");
-                    let row = source
-                        .outputs
-                        .iter()
-                        .position(|port| port.key == from.port)
-                        .expect("a wiring port");
-                    Some((source.socket(true, row), *to, from.kind.clone()))
+                    let source = nodes.iter().find(|node| node.key == from.node);
+                    let wiring = source.and_then(|source| {
+                        let row = source
+                            .outputs
+                            .iter()
+                            .position(|port| port.key == from.port)?;
+                        Some((
+                            source.socket(true, row),
+                            *to,
+                            source.outputs[row].kind.clone(),
+                        ))
+                    });
+                    if wiring.is_none() {
+                        log::error!(
+                            "node editor: the wire's port {}.{} left the graph",
+                            from.node,
+                            from.port
+                        );
+                    }
+                    wiring
                 }
                 _ => None,
             };
@@ -353,10 +366,8 @@ impl RenderOnce for NodeGraph {
                     let drawn = edges
                         .iter()
                         .filter(|edge| Some(*edge) != lifted.as_ref())
-                        .map(|edge| {
-                            let (from, to, kind) = ends(&nodes, edge);
-                            (from, to, hue(&kind))
-                        })
+                        .filter_map(|edge| ends(&nodes, edge))
+                        .map(|(from, to, kind)| (from, to, hue(&kind)))
                         .chain(
                             pending
                                 .iter()

src/canvas/palette.rs

@@ -66,12 +66,13 @@ impl ToolPalette {
 
 impl RenderOnce for ToolPalette {
     fn render(self, _: &mut Window, _: &mut App) -> impl IntoElement {
-        assert!(
-            self.tools.contains(&self.tool),
-            "tool palette {:?}: {} is not offered",
-            self.id,
-            self.tool.words()
-        );
+        if !self.tools.contains(&self.tool) {
+            log::error!(
+                "tool palette {:?}: {} is not offered; none chosen",
+                self.id,
+                self.tool.words()
+            );
+        }
         let on_change = self.on_change;
         self.tools
             .into_iter()

src/canvas/plane.rs

@@ -167,15 +167,14 @@ impl RenderOnce for InfiniteCanvas {
             .links
             .iter()
             .filter_map(|link| {
-                let named = |key: &SharedString| {
-                    self.shapes
-                        .iter()
-                        .find(|shape| shape.key == *key)
-                        .unwrap_or_else(|| {
-                            panic!("link {} names {key}, which is not on the canvas", link.key)
-                        })
+                let named = |key: &SharedString| self.shapes.iter().find(|shape| shape.key == *key);
+                let (Some(from), Some(to)) = (named(&link.from), named(&link.to)) else {
+                    log::error!(
+                        "canvas: link {} names a shape gone from the canvas",
+                        link.key
+                    );
+                    return None;
                 };
-                let (from, to) = (named(&link.from), named(&link.to));
                 (!from.hidden && !to.hidden).then(|| {
                     let points = route(&from.frame, &to.frame, link.elbow)
                         .into_iter()

src/canvas/style.rs

@@ -23,16 +23,20 @@ pub struct ColorPanel {
     id: ElementId,
     color: Hsla,
     swatches: Vec<(SharedString, Hsla)>,
-    on_change: Option<OnEdit<Hsla>>,
+    on_change: OnEdit<Hsla>,
 }
 
 impl ColorPanel {
-    pub fn new(id: impl Into<ElementId>, color: impl Into<Hsla>) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        color: impl Into<Hsla>,
+        on_change: impl Fn(Hsla, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             color: color.into(),
             swatches: Vec::new(),
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
 
@@ -47,18 +51,11 @@ impl ColorPanel {
             .collect();
         self
     }
-
-    pub fn on_change(mut self, handler: impl Fn(Hsla, &mut Window, &mut App) + 'static) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 impl RenderOnce for ColorPanel {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("color panel {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let (picked, chosen) = (on_change.clone(), on_change);
         let report = |on_change: OnEdit<Hsla>| {
             move |color: Hsla, window: &mut Window, cx: &mut App| {
@@ -98,32 +95,26 @@ pub struct Shadow {
 pub struct ShadowEditor {
     id: ElementId,
     shadows: Vec<Shadow>,
-    on_change: Option<OnEdit<Vec<Shadow>>>,
+    on_change: OnEdit<Vec<Shadow>>,
 }
 
 impl ShadowEditor {
-    pub fn new(id: impl Into<ElementId>, shadows: impl IntoIterator<Item = Shadow>) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        shadows: impl IntoIterator<Item = Shadow>,
+        on_change: impl Fn(Vec<Shadow>, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             shadows: shadows.into_iter().collect(),
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
-
-    pub fn on_change(
-        mut self,
-        handler: impl Fn(Vec<Shadow>, &mut Window, &mut App) + 'static,
-    ) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 impl RenderOnce for ShadowEditor {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("shadow editor {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let lift = cx
             .theme()
             .elevation(Elevation::Floating)
@@ -247,31 +238,28 @@ pub struct Border {
 pub struct BorderEditor {
     id: ElementId,
     border: Border,
-    on_change: Option<OnEdit<Border>>,
+    on_change: OnEdit<Border>,
 }
 
 impl BorderEditor {
-    pub fn new(id: impl Into<ElementId>, border: Border) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        border: Border,
+        on_change: impl Fn(Border, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             border,
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
-
-    pub fn on_change(mut self, handler: impl Fn(Border, &mut Window, &mut App) + 'static) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 const CORNERS: [&str; 4] = ["TL", "TR", "BR", "BL"];
 
 impl RenderOnce for BorderEditor {
     fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("border editor {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let (id, border, on_change) = (self.id, self.border, &on_change);
         let parted = window.use_keyed_state((id.clone(), "split"), cx, |_, _| false);
         let uneven = border.radii.iter().any(|radius| *radius != border.radii[0]);

src/canvas/tests/boards.rs

@@ -2,7 +2,7 @@ use gpui::{AnyElement, Entity, IntoElement, TestAppContext, VisualTestContext};
 
 use super::{
     Stage, said, say, settle, stage,
-    tools::{drag, layer, pair, press},
+    tools::{at, drag, layer, pair, press},
 };
 use crate::canvas::{
     Board, Edge, Link, MindMap, Node, NodeGraph, Port, Tool, Topic, Viewport, Whiteboard,
@@ -245,3 +245,134 @@ fn after_writing_on_a_shape_its_board_still_takes_backspace(cx: &mut TestAppCont
         ["shapes [\"a\", \"b\"] links 1", "shapes [\"a\"] links 0"]
     );
 }
+
+/// Presses at `from` and drags to `to` in four moves.
+fn pull(from: (f32, f32), to: (f32, f32), cx: &mut VisualTestContext) {
+    use gpui::{Modifiers, MouseButton};
+    cx.simulate_mouse_move(at(from.0, from.1), None, Modifiers::none());
+    cx.simulate_mouse_down(at(from.0, from.1), MouseButton::Left, Modifiers::none());
+    for step in 1..=4 {
+        let share = step as f32 / 4.0;
+        let (x, y) = (
+            from.0 + (to.0 - from.0) * share,
+            from.1 + (to.1 - from.1) * share,
+        );
+        cx.simulate_mouse_move(at(x, y), Some(MouseButton::Left), Modifiers::none());
+        settle(cx);
+    }
+}
+
+fn release(to: (f32, f32), cx: &mut VisualTestContext) {
+    let (left, none) = (gpui::MouseButton::Left, gpui::Modifiers::none());
+    cx.simulate_mouse_up(at(to.0, to.1), left, none);
+    settle(cx);
+}
+
+/// The owner changes what it hands the part, mid-gesture.
+fn change(host: &Entity<Stage>, cx: &mut VisualTestContext) {
+    host.update(cx, |stage, cx| {
+        stage.said.push("owner changed".into());
+        cx.notify();
+    });
+    settle(cx);
+}
+
+#[gpui::test]
+fn f2_on_a_selected_topic_that_left_renames_nothing(cx: &mut TestAppContext) {
+    let (_, cx) = stage(
+        |_, _| {
+            let view = Viewport::new(-200.0, -150.0, 1.0);
+            MindMap::new("map", Topic::new("root", "Root"), view)
+                .selected(Some("gone"))
+                .into_any_element()
+        },
+        cx,
+    );
+    press(200.0, 150.0, 1, cx);
+    tap("f2", cx);
+}
+
+/// Two wireable nodes whose source leaves, or changes kind, once the owner changes.
+fn shifting(stage: &Stage, owner: Entity<Stage>, retype: bool) -> AnyElement {
+    let mut current = nodes();
+    if !stage.said.is_empty() {
+        match retype {
+            true => current[0].outputs[0].kind = "number".into(),
+            false => drop(current.remove(0)),
+        }
+    }
+    NodeGraph::new("graph", Viewport::new(0.0, 0.0, 1.0), current, [])
+        .on_connect(move |edge, _, cx| {
+            let words = format!(
+                "connect {}.{} {}.{}",
+                edge.from.0, edge.from.1, edge.to.0, edge.to.1
+            );
+            say(&owner, words, cx)
+        })
+        .into_any_element()
+}
+
+#[gpui::test]
+fn a_wire_whose_source_left_connects_nothing(cx: &mut TestAppContext) {
+    let (host, cx) = stage(|stage, owner| shifting(stage, owner, false), cx);
+    pull((200.0, 46.0), (301.0, 47.0), cx);
+    change(&host, cx);
+    release((301.0, 47.0), cx);
+    assert_eq!(said(&host, cx), ["owner changed"]);
+}
+
+#[gpui::test]
+fn a_wire_whose_source_changed_kind_connects_nothing(cx: &mut TestAppContext) {
+    let (host, cx) = stage(|stage, owner| shifting(stage, owner, true), cx);
+    pull((200.0, 46.0), (301.0, 47.0), cx);
+    change(&host, cx);
+    release((301.0, 47.0), cx);
+    assert_eq!(said(&host, cx), ["owner changed"]);
+}
+
+#[gpui::test]
+fn a_link_whose_shape_left_links_nothing(cx: &mut TestAppContext) {
+    let (host, cx) = stage(
+        |stage, owner| {
+            let mut shapes = pair();
+            if !stage.said.is_empty() {
+                shapes.remove(0);
+            }
+            let view = Viewport::new(0.0, 0.0, 1.0);
+            let tool =
+                crate::canvas::ToolLayer::new("layer", Tool::Connector, view, shapes.clone())
+                    .on_link(move |from, to, _, cx| say(&owner, format!("link {from} {to}"), cx));
+            crate::canvas::InfiniteCanvas::new("plane", view)
+                .shapes(shapes)
+                .layer(tool)
+                .into_any_element()
+        },
+        cx,
+    );
+    pull((50.0, 50.0), (250.0, 60.0), cx);
+    change(&host, cx);
+    release((250.0, 60.0), cx);
+    assert_eq!(said(&host, cx), ["owner changed"]);
+}
+
+#[gpui::test]
+fn a_layer_that_left_mid_drag_restacks_nothing(cx: &mut TestAppContext) {
+    let (host, cx) = stage(
+        |stage, owner| {
+            let mut shapes = pair();
+            if !stage.said.is_empty() {
+                shapes.remove(0);
+            }
+            crate::canvas::LayerPanel::new("layers", shapes)
+                .on_restack(move |keys, _, cx| say(&owner, format!("restack {keys:?}"), cx))
+                .into_any_element()
+        },
+        cx,
+    );
+    let a = cx.debug_bounds("tree-chevron-a").expect("a row").center();
+    let b = cx.debug_bounds("tree-chevron-b").expect("b row").center();
+    pull((100.0, f32::from(a.y)), (100.0, f32::from(b.y)), cx);
+    change(&host, cx);
+    release((100.0, f32::from(b.y)), cx);
+    assert_eq!(said(&host, cx), ["owner changed"]);
+}

src/canvas/tests/mod.rs

@@ -9,6 +9,7 @@ use crate::{primitives::FocusNext, theme::Theme};
 
 mod boards;
 mod panels;
+mod stale;
 mod tools;
 
 /// A view that shows one canvas part and keeps the viewports and words it heard.

src/canvas/tests/panels.rs

@@ -59,9 +59,10 @@ fn places(_: &Stage, owner: Entity<Stage>) -> AnyElement {
         padding: (8.0, 8.0),
         place: (Place::Start, Place::Start),
     };
-    AutoLayoutControls::new("auto", layout)
-        .on_change(move |next, _, cx| say(&owner, format!("{:?}", next.place), cx))
-        .into_any_element()
+    AutoLayoutControls::new("auto", layout, move |next, _, cx| {
+        say(&owner, format!("{:?}", next.place), cx)
+    })
+    .into_any_element()
 }
 
 #[gpui::test]
@@ -89,12 +90,12 @@ fn sizes(_: &Stage, owner: Entity<Stage>) -> AnyElement {
             scale: 1.0,
             format: ExportFormat::Png,
         }],
+        move |next, _, cx| {
+            let scales: Vec<f32> = next.iter().map(|setting| setting.scale).collect();
+            say(&added, format!("sizes {scales:?}"), cx)
+        },
+        move |files, _, cx| say(&sent, format!("files {files:?}"), cx),
     )
-    .on_change(move |next, _, cx| {
-        let scales: Vec<f32> = next.iter().map(|setting| setting.scale).collect();
-        say(&added, format!("sizes {scales:?}"), cx)
-    })
-    .on_export(move |files, _, cx| say(&sent, format!("files {files:?}"), cx))
     .into_any_element()
 }
 

src/canvas/tests/stale.rs

@@ -0,0 +1,43 @@
+use gpui::{AnyElement, Entity, IntoElement, ParentElement, Styled, TestAppContext, div, px};
+
+use super::{Stage, settle, stage};
+use crate::canvas::{
+    Edge, Frame, HistoryPanel, InfiniteCanvas, Link, MindMap, Node, NodeGraph, Port, Shape,
+    ShapeKind, Tool, ToolPalette, Topic, Viewport,
+};
+
+/// Each part handed a key or an edge that its list no longer holds.
+fn lagging(_: &Stage, _: Entity<Stage>) -> AnyElement {
+    let view = Viewport::new(0.0, 0.0, 1.0);
+    let load = Node::new("load", "Load", (0.0, 0.0)).output(Port::new("image", "Image", "image"));
+    let shape = Shape::new("a", "A", ShapeKind::Rect, Frame::new(0.0, 0.0, 40.0, 40.0));
+    div()
+        .size_full()
+        .child(div().h(px(120.0)).child(NodeGraph::new(
+            "graph",
+            view,
+            [load],
+            [Edge::new(("load", "image"), ("gone", "image"))],
+        )))
+        .child(
+            div().h(px(120.0)).child(
+                InfiniteCanvas::new("plane", view)
+                    .shapes([shape])
+                    .links([Link::new("l", "a", "gone")]),
+            ),
+        )
+        .child(
+            div().h(px(120.0)).child(
+                MindMap::new("map", Topic::new("root", "Root"), view).selected(Some("gone")),
+            ),
+        )
+        .child(ToolPalette::new("tools", Tool::Brush).tools([Tool::Select]))
+        .child(HistoryPanel::new("history", ["Draw"], 4))
+        .into_any_element()
+}
+
+#[gpui::test]
+fn gone_nodes_shapes_topics_tools_and_steps_draw(cx: &mut TestAppContext) {
+    let (_, cx) = stage(lagging, cx);
+    settle(cx);
+}

src/canvas/tools.rs

@@ -228,16 +228,18 @@ impl RenderOnce for ToolLayer {
             Gesture::Stroke { points } if points.len() > 1 => {
                 vec![stroke_shape(points, self.brush.size, self.brush.hue)]
             }
-            Gesture::Linking { from, to } => {
-                let start = shapes
-                    .iter()
-                    .find(|shape| shape.key == *from)
-                    .expect("a link starts on a listed shape")
-                    .frame
-                    .center();
-                let (kind, frame) = drawn(ShapeKind::Arrow(Corner::BottomRight), start, *to, false);
-                vec![Shape::new("+link", "Link", kind, frame)]
-            }
+            Gesture::Linking { from, to } => match shapes.iter().find(|shape| shape.key == *from) {
+                Some(start) => {
+                    let start = start.frame.center();
+                    let (kind, frame) =
+                        drawn(ShapeKind::Arrow(Corner::BottomRight), start, *to, false);
+                    vec![Shape::new("+link", "Link", kind, frame)]
+                }
+                None => {
+                    log::error!("tool layer: the link's shape {from} left the canvas");
+                    Vec::new()
+                }
+            },
             _ if tool == Tool::Pen && pen.len() > 1 => {
                 vec![stroke_shape(&pen, PEN, self.brush.hue)]
             }

src/canvas/typography.rs

@@ -48,34 +48,29 @@ pub struct TypographyPanel {
     id: ElementId,
     style: TypeStyle,
     search: Entity<TextInput>,
-    on_change: Option<OnEdit<TypeStyle>>,
+    on_change: OnEdit<TypeStyle>,
 }
 
 impl TypographyPanel {
     /// `search` is the family field's text, which the owner keeps.
-    pub fn new(id: impl Into<ElementId>, style: TypeStyle, search: &Entity<TextInput>) -> Self {
+    pub fn new(
+        id: impl Into<ElementId>,
+        style: TypeStyle,
+        search: &Entity<TextInput>,
+        on_change: impl Fn(TypeStyle, &mut Window, &mut App) + 'static,
+    ) -> Self {
         Self {
             id: id.into(),
             style,
             search: search.clone(),
-            on_change: None,
+            on_change: Rc::new(on_change),
         }
     }
-
-    pub fn on_change(
-        mut self,
-        handler: impl Fn(TypeStyle, &mut Window, &mut App) + 'static,
-    ) -> Self {
-        self.on_change = Some(Rc::new(handler));
-        self
-    }
 }
 
 impl RenderOnce for TypographyPanel {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
-        let on_change = self
-            .on_change
-            .unwrap_or_else(|| panic!("typography panel {:?} has no on_change", self.id));
+        let on_change = self.on_change;
         let (id, style, on_change) = (self.id, self.style, &on_change);
         let theme = cx.theme();
         let family = editing(

src/canvas/whiteboard.rs

@@ -195,11 +195,11 @@ impl RenderOnce for Whiteboard {
                 let key = key.clone();
                 sized(
                     &|board, _| {
-                        let shape = board
-                            .shapes
-                            .iter_mut()
-                            .find(|shape| shape.key == key)
-                            .expect("a resized shape is on the board");
+                        let Some(shape) = board.shapes.iter_mut().find(|shape| shape.key == key)
+                        else {
+                            log::error!("whiteboard: resized shape {key} left the board");
+                            return;
+                        };
                         shape.frame = frame;
                     },
                     window,
@@ -235,11 +235,11 @@ impl RenderOnce for Whiteboard {
                 let (key, text) = (key.clone(), text.clone());
                 written(
                     &|board, _| {
-                        let shape = board
-                            .shapes
-                            .iter_mut()
-                            .find(|shape| shape.key == key)
-                            .expect("a written shape is on the board");
+                        let Some(shape) = board.shapes.iter_mut().find(|shape| shape.key == key)
+                        else {
+                            log::error!("whiteboard: written shape {key} left the board");
+                            return;
+                        };
                         *shape = shape.written(text.clone());
                     },
                     window,

src/canvas/wiring.rs

@@ -66,6 +66,23 @@ impl Ending {
                 }
             }
             Pull::Wiring { from, lifted, to } => {
+                let kind = self
+                    .nodes
+                    .iter()
+                    .find(|node| node.key == from.node)
+                    .and_then(|node| {
+                        let port = node.outputs.iter().find(|port| port.key == from.port)?;
+                        Some(port.kind.clone())
+                    });
+                let Some(kind) = kind else {
+                    log::error!(
+                        "node graph: the wire's port {}.{} left the graph",
+                        from.node,
+                        from.port
+                    );
+                    return;
+                };
+                let from = Socket { kind, ..from };
                 let target =
                     socket_at(&self.nodes, to, REACH / self.zoom).filter(|to| fits(&from, to));
                 let made = target.map(|to| {

tasks/panics.md

@@ -46,7 +46,7 @@ Each item reads every site in its folders, fixes what the rules name, updates ca
 - [x] P29 Mail — `src/mail`
 - [x] P30 Calendar — `src/calendar`
 - [x] P31 Project — `src/project`
-- [ ] P32 Canvas & Design — `src/canvas`
+- [x] P32 Canvas & Design — `src/canvas`
 - [ ] P33 DB & Dev Tools — `src/devtools`
 - [ ] P34 Dashboard — `src/dashboard`
 - [ ] P35 Settings — `src/settings`
@@ -97,3 +97,4 @@ One line per item: what changed, what stayed and why, review rounds.
 - P29: an open mailbox, ticked label or selected mail no longer listed logs and marks none; a picked moment its zone cannot hold logs and reads as none, so the time dialog's action stays off. Kept: one list's uniqueness, day arithmetic from the owner's now, constant `datetime` patterns, the dialog's action behind its disabled button. Review: 1 round.
 - P30: calendar views step only within jiff's range less a year at each end (`calendar::within`, `stepped`), so every grid around a day fits, and a step past logs and stays; recurrences end where jiff's range ends; the year view's marks stop at an event's last day; the event editor refuses moves, ends, all-day starts and switches to timed that leave jiff's range or a stale painted kind, each with a log; a backward timed draft's days are its first day. Kept: owner dates at jiff's far edges, one list's uniqueness, an event's own order, one organizer, working hours, slots, reminder offsets, constant patterns, picks that always name a value. Review: 2 rounds.
 - P31: a gone assignee logs and shows nobody; a milestone past its count fills, the text real; a roadmap past jiff's range ends inclusively on its last day; the database timeline leaves out and counts tasks due before they start and counts months in `i32`, and its calendar keeps to days `calendar::within` holds; the board's drag and drop take only columns, cards and places this frame holds. Kept: one list's uniqueness, an initiative's and a milestone's own order, shares, month counts, pomodoro lengths, issue keys, lookups over the components' own tables. Review: 3 rounds.
+- P32: the eight design panels take their handlers in `new` (AGENTS.md says so); edges, links, wires, links in progress, resizes, restacks, topics and whiteboard edits that name a node, port, shape, layer or topic gone from this frame log and change nothing; a wire's release fits its source as it now stands; `Topic::adding`, `removing` and `renaming` return `Option`; a mind map's selection, a palette's tool and a history position no longer held mark none. Kept: one-value contracts (alignment counts, frames, zoom, polygon sides, brush hues and type weights among the theme's tables), lookups over the panels' own option tables, button-gated expects. Review: 2 rounds.