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

crates/oa-core/src/validation.rs

@@ -731,6 +731,40 @@ pub fn validate(p: &Project) -> Vec<Issue> {
         }
         let mut elements = BTreeSet::new();
         for (key, n) in &d.nodes {
+            let mut ports = BTreeSet::new();
+            for anchor in &n.port_anchors {
+                if !ports.insert(anchor.port) {
+                    error(
+                        &mut out,
+                        n.id,
+                        "duplicate_port_anchor",
+                        "port_anchors",
+                        "Each port has at most one manual anchor per owner placement.",
+                    );
+                }
+                if !p
+                    .elements
+                    .get(&anchor.port)
+                    .is_some_and(|e| e.kind() == Kind::Port && e.parent == Some(n.element))
+                {
+                    error(
+                        &mut out,
+                        n.id,
+                        "port_anchor_owner",
+                        "port_anchors",
+                        "A manual anchor must reference a direct child port of its owner placement; repair anchors in the same transaction when reparenting.",
+                    );
+                }
+                if !anchor.offset.is_finite() || !(0. ..=1.).contains(&anchor.offset) {
+                    error(
+                        &mut out,
+                        n.id,
+                        "invalid_port_offset",
+                        "port_anchors",
+                        "Port offset must be finite and between zero and one.",
+                    );
+                }
+            }
             if *key != n.id {
                 error(
                     &mut out,