refactor: extract tag gravity force logic to top-level applyTagGravity helper

src/lib/navigator/EventNetwork/utils/tagNetworkBuilder.ts

@@ -233,36 +233,17 @@ export function enhanceGraphWithTags(
 }
 
 /**
- * Custom force for tag anchor gravity
+ * Applies a gentle pull on each node toward its tag anchors.
+ *
+ * @param nodes - The array of network nodes to update.
+ * @param nodeToAnchors - A map from node IDs to their tag anchor nodes.
+ * @param alpha - The current simulation alpha (cooling factor).
  */
-export function createTagGravityForce(
+export function applyTagGravity(
   nodes: NetworkNode[],
-  links: NetworkLink[],
-): any {
-  // Build a map of nodes to their tag anchors
-  const nodeToAnchors = new Map<string, NetworkNode[]>();
-
-  links.forEach((link) => {
-    const source = link.source as NetworkNode;
-    const target = link.target as NetworkNode;
-
-    if (source.isTagAnchor && !target.isTagAnchor) {
-      if (!nodeToAnchors.has(target.id)) {
-        nodeToAnchors.set(target.id, []);
-      }
-      nodeToAnchors.get(target.id)!.push(source);
-    } else if (target.isTagAnchor && !source.isTagAnchor) {
-      if (!nodeToAnchors.has(source.id)) {
-        nodeToAnchors.set(source.id, []);
-      }
-      nodeToAnchors.get(source.id)!.push(target);
-    }
-  });
-
-  debug("Creating tag gravity force");
-  
-  // Custom force function
-  function force(alpha: number) {
+  nodeToAnchors: Map<string, NetworkNode[]>,
+  alpha: number
+): void {
   nodes.forEach((node) => {
     if (node.isTagAnchor) return; // Tag anchors don't move
 
@@ -290,6 +271,39 @@ export function createTagGravityForce(
       }
     });
   });
+}
+
+/**
+ * Custom force for tag anchor gravity
+ */
+export function createTagGravityForce(
+  nodes: NetworkNode[],
+  links: NetworkLink[],
+): any {
+  // Build a map of nodes to their tag anchors
+  const nodeToAnchors = new Map<string, NetworkNode[]>();
+
+  links.forEach((link) => {
+    const source = link.source as NetworkNode;
+    const target = link.target as NetworkNode;
+
+    if (source.isTagAnchor && !target.isTagAnchor) {
+      if (!nodeToAnchors.has(target.id)) {
+        nodeToAnchors.set(target.id, []);
+      }
+      nodeToAnchors.get(target.id)!.push(source);
+    } else if (target.isTagAnchor && !source.isTagAnchor) {
+      if (!nodeToAnchors.has(source.id)) {
+        nodeToAnchors.set(source.id, []);
+      }
+      nodeToAnchors.get(source.id)!.push(target);
+    }
+  });
+
+  debug("Creating tag gravity force");
+
+  function force(alpha: number) {
+    applyTagGravity(nodes, nodeToAnchors, alpha);
   }
 
   force.initialize = function (_: NetworkNode[]) {