Add persisted per-view port anchors and connection-aware border placement

crates/oa-core/src/session.rs

@@ -44,6 +44,16 @@ pub enum Command {
         diagram: Id,
         edge: Id,
     },
+    SetPortAnchor {
+        diagram: Id,
+        node: Id,
+        anchor: PortAnchor,
+    },
+    RemovePortAnchor {
+        diagram: Id,
+        node: Id,
+        port: Id,
+    },
     RelocateNode {
         node: Id,
         diagram: Id,
@@ -679,6 +689,45 @@ fn apply_command(
                 .ok_or_else(missing)? = value.clone();
             Some(*owner)
         }
+        Command::SetPortAnchor {
+            diagram,
+            node,
+            anchor,
+        } => {
+            let n = p
+                .diagrams
+                .get_mut(diagram)
+                .and_then(|d| d.nodes.get_mut(node))
+                .ok_or_else(missing)?;
+            if let Some(existing) = n.port_anchors.iter_mut().find(|a| a.port == anchor.port) {
+                *existing = anchor.clone();
+            } else {
+                n.port_anchors.push(anchor.clone());
+            }
+            Some(anchor.port)
+        }
+        Command::RemovePortAnchor {
+            diagram,
+            node,
+            port,
+        } => {
+            let n = p
+                .diagrams
+                .get_mut(diagram)
+                .and_then(|d| d.nodes.get_mut(node))
+                .ok_or_else(missing)?;
+            if !p
+                .elements
+                .get(port)
+                .is_some_and(|e| e.kind() == Kind::Port && e.parent == Some(n.element))
+            {
+                return Err(ModelError(
+                    "Port positioning requires a direct child port of the owner placement.".into(),
+                ));
+            }
+            n.port_anchors.retain(|anchor| anchor.port != *port);
+            Some(*port)
+        }
         Command::SetEdgeRoute { diagram, route } => {
             let d = p.diagrams.get_mut(diagram).ok_or_else(missing)?;
             if let Some(existing) = d.routes.iter_mut().find(|r| r.edge == route.edge) {