added typeaheead and introspetion

DBSyn/SchemaDiagramView.swift

@@ -14,6 +14,30 @@ private struct DiagramPoint: Codable {
     var y: Double
 }
 
+// Keep the drag translation local to the node. Updating the entire diagram's
+// positions dictionary on every mouse event caused layout churn and jerky drags.
+private struct DiagramDraggableNode<Content: View>: View {
+    let zoom: CGFloat
+    let onDrop: (CGSize) -> Void
+    @ViewBuilder let content: () -> Content
+    @GestureState private var translation: CGSize = .zero
+
+    var body: some View {
+        content()
+            .offset(x: translation.width / max(zoom, 0.1),
+                    y: translation.height / max(zoom, 0.1))
+            .highPriorityGesture(
+                DragGesture(minimumDistance: 3, coordinateSpace: .global)
+                    .updating($translation) { value, state, _ in
+                        state = value.translation
+                    }
+                    .onEnded { value in
+                        onDrop(value.translation)
+                    }
+            )
+    }
+}
+
 @MainActor
 struct DBSynSchemaDiagramView: View {
     @ObservedObject var model: DatabaseModel
@@ -219,9 +243,17 @@ struct DBSynSchemaDiagramView: View {
                             }
                         }
                         ForEach(objects, id: \.self) { name in
-                            diagramNode(name)
-                                .position(x: position(name).x + nodeWidth / 2,
-                                          y: position(name).y + height(name) / 2)
+                            DiagramDraggableNode(zoom: zoom, onDrop: { translation in
+                                let start = position(name)
+                                positions[name] = CGPoint(
+                                    x: max(10, start.x + translation.width / max(zoom, 0.1)),
+                                    y: max(10, start.y + translation.height / max(zoom, 0.1)))
+                                savePositions()
+                            }) {
+                                diagramNode(name)
+                            }
+                            .position(x: position(name).x + nodeWidth / 2,
+                                      y: position(name).y + height(name) / 2)
                         }
                     }
                     .frame(width: canvasWidth, height: canvasHeight, alignment: .topLeading)
@@ -317,18 +349,7 @@ struct DBSynSchemaDiagramView: View {
         .shadow(color: .black.opacity(0.13), radius: 3, y: 2)
         .opacity(related ? 1 : 0.4)
         .onTapGesture { selectedObject = selectedObject == name ? nil : name }
-        .gesture(DragGesture(minimumDistance: 4)
-            .onChanged { value in
-                let current = position(name)
-                // DragGesture.translation is relative to the gesture start.
-                if dragOrigins[name] == nil { dragOrigins[name] = current }
-                let start = dragOrigins[name] ?? current
-                positions[name] = CGPoint(x: max(10, start.x + value.translation.width / zoom),
-                                          y: max(10, start.y + value.translation.height / zoom))
-            }
-            .onEnded { _ in dragOrigins.removeValue(forKey: name); savePositions() })
     }
-    @State private var dragOrigins: [String: CGPoint] = [:]
 
     // Rebuild the visible canvas whenever the selected objects change. The
     // previous implementation only saved the checkboxes, leaving the diagram