Implement interactive pushpins and drag-to-connect red yarn webbing for Evidence Board

server/index.js

@@ -83,6 +83,7 @@ function readDeskState() {
             cards: desk.cards || [],
             props: desk.props || [],
             strokes: desk.strokes || [],
+            yarnLinks: desk.yarnLinks || [],
             settings: desk.settings || {}
           }
         };
@@ -155,7 +156,7 @@ app.get('/api/desk', (_req, res) => {
 
 // Save desk state
 app.post('/api/desk', (req, res) => {
-  const { cards, props, strokes, settings, activeBoard, boards, originClientId } = req.body;
+  const { cards, props, strokes, yarnLinks, settings, activeBoard, boards, originClientId } = req.body;
 
   if (!Array.isArray(cards)) {
     return res.status(400).json({ success: false, error: 'Invalid desk state: cards required' });
@@ -167,6 +168,7 @@ app.post('/api/desk', (req, res) => {
     cards,
     props: Array.isArray(props) ? props : [],
     strokes: Array.isArray(strokes) ? strokes : [],
+    yarnLinks: Array.isArray(yarnLinks) ? yarnLinks : (updatedBoards[currentBoard]?.yarnLinks || []),
     settings: settings || {}
   };
 
@@ -174,6 +176,7 @@ app.post('/api/desk', (req, res) => {
     cards,
     props: Array.isArray(props) ? props : [],
     strokes: Array.isArray(strokes) ? strokes : [],
+    yarnLinks: Array.isArray(yarnLinks) ? yarnLinks : [],
     settings: settings || {},
     activeBoard: currentBoard,
     boards: updatedBoards,