Track view-scoped overlay placements and retain portalled editors

tests/headless/renderer.integration.mjs

@@ -344,6 +344,7 @@ try {
   await until(`!!document.querySelector('[aria-label="分区名称"]')`,'frame title editor did not open');
   await click('收起子画布');await until(`!document.querySelector('.react-flow__node[data-id=b]')&&document.querySelectorAll('.react-flow__edge').length>0`,'collapsed partition did not render its upper-canvas connection');assert.equal(documents.get(root).elements.get('edge').target.elementId,'b');assert.ok(documents.get(root).elements.has('b'));await click('展开子画布');await until(`!!document.querySelector('.react-flow__node[data-id=b] textarea')`,'expanding partition did not restore the member');
   console.log('PASS collapsed partitions retain model endpoints and render upper-canvas connections through headless frame anchors');
+  assert.ok(await evaluate(`document.querySelector('[aria-label="分区名称"]').closest('[data-canvas-overlay-target]')?.dataset.canvasOverlayView`),'portalled frame title did not register its explicit view/target placement');
   await evaluate(`(()=>{window.pinnedFrameTitle=document.querySelector('[aria-label="分区名称"]');window.pinnedFrameTitle.focus();window.pinnedFrameTitle.select();})()`);await call('Input.insertText',{text:'Pinned partition draft'});
   const panFar=`document.querySelector('.react-flow__pane').dispatchEvent(new WheelEvent('wheel',{deltaX:20000,deltaY:20000,bubbles:true,cancelable:true}))`,panHome=`(()=>{const matrix=new DOMMatrix(getComputedStyle(document.querySelector('.react-flow__viewport')).transform);document.querySelector('.react-flow__pane').dispatchEvent(new WheelEvent('wheel',{deltaX:matrix.e/.5,deltaY:matrix.f/.5,bubbles:true,cancelable:true}));})()`;
   await evaluate(panFar);await pause(250);assert.equal(await evaluate(`window.pinnedFrameTitle.isConnected&&document.activeElement===window.pinnedFrameTitle&&window.pinnedFrameTitle.value==='Pinned partition draft'`),true,'viewport culling discarded an unsaved frame title');