fix: @ mention popup appears above cursor with correct positioning

- Popup now appears above the cursor line (matching reference design)
- Header changed to "可能@的内容"
- @ character stays visible while popup is open, removed on mention select
- All references shown in popup (no dedup filtering)
- Fixed zero-rect fallback using temp marker for empty editor

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/components/PromptInput.module.css

@@ -50,7 +50,7 @@
   color: rgba(0, 184, 230, 0.9);
 }
 
-/* Mention popup */
+/* Mention popup — appears above cursor */
 .mentionPopup {
   position: absolute;
   z-index: 100;
@@ -61,12 +61,13 @@
   min-width: 200px;
   max-width: 280px;
   box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
-  animation: fadeIn 0.12s ease;
+  transform: translateY(-100%);
+  animation: fadeInUp 0.12s ease;
 }
 
-@keyframes fadeIn {
+@keyframes fadeInUp {
-  from { opacity: 0; transform: translateY(-4px); }
+  from { opacity: 0; transform: translateY(-100%) translateY(4px); }
-  to { opacity: 1; transform: translateY(0); }
+  to { opacity: 1; transform: translateY(-100%); }
 }
 
 .mentionHeader {

web/src/components/PromptInput.tsx

@@ -20,6 +20,7 @@ export function PromptInput() {
   const editorRef = useRef<HTMLDivElement>(null);
   const [showMentionPopup, setShowMentionPopup] = useState(false);
   const [mentionPos, setMentionPos] = useState({ top: 0, left: 0 });
+  const typedAtRef = useRef(false); // tracks if popup was triggered by typing @
   const [hoverRef, setHoverRef] = useState<UploadedFile | null>(null);
   const [hoverPos, setHoverPos] = useState({ top: 0, left: 0 });
 
@@ -41,6 +42,7 @@ export function PromptInput() {
   useEffect(() => {
     if (insertAtTrigger === 0) return;
     if (references.length === 0) return;
+    typedAtRef.current = false;
     openMentionPopup();
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [insertAtTrigger]);
@@ -51,16 +53,33 @@ export function PromptInput() {
     el.focus();
 
     const sel = window.getSelection();
-    if (!sel || sel.rangeCount === 0) return;
-
-    const range = sel.getRangeAt(0);
-    const rect = range.getBoundingClientRect();
     const editorRect = el.getBoundingClientRect();
 
-    setMentionPos({
+    // Position popup above cursor line
-      top: rect.bottom - editorRect.top + 4,
+    let top = 0; // fallback: top of editor
-      left: Math.max(0, rect.left - editorRect.left),
+    let left = 0;
-    });
+
+    if (sel && sel.rangeCount > 0) {
+      const range = sel.getRangeAt(0);
+      const rect = range.getBoundingClientRect();
+
+      if (rect.height > 0) {
+        top = rect.top - editorRect.top - 8;
+        left = Math.max(0, rect.left - editorRect.left);
+      } else {
+        // Collapsed range returns zero rect — use temp marker
+        const marker = document.createElement('span');
+        marker.textContent = '\u200B';
+        range.insertNode(marker);
+        const mRect = marker.getBoundingClientRect();
+        top = mRect.top - editorRect.top - 8;
+        left = Math.max(0, mRect.left - editorRect.left);
+        marker.remove();
+        el.normalize();
+      }
+    }
+
+    setMentionPos({ top, left });
     setShowMentionPopup(true);
   }, []);
 
@@ -84,18 +103,8 @@ export function PromptInput() {
     const text = node.textContent || '';
     const offset = range.startOffset;
     if (offset > 0 && text[offset - 1] === '@' && references.length > 0) {
-      // Remove the typed @
+      // Keep the @ visible, open popup above it
-      const before = text.substring(0, offset - 1);
+      typedAtRef.current = true;
-      const after = text.substring(offset);
-      node.textContent = before + after;
-
-      // Restore cursor
-      const newRange = document.createRange();
-      newRange.setStart(node, before.length);
-      newRange.collapse(true);
-      sel.removeAllRanges();
-      sel.addRange(newRange);
-
       openMentionPopup();
     }
   }, [extractText, references.length, openMentionPopup]);
@@ -110,6 +119,23 @@ export function PromptInput() {
     if (!sel || sel.rangeCount === 0) return;
 
     const range = sel.getRangeAt(0);
+
+    // If triggered by typing @, remove the @ character first
+    if (typedAtRef.current) {
+      typedAtRef.current = false;
+      const node = range.startContainer;
+      if (node.nodeType === Node.TEXT_NODE) {
+        const text = node.textContent || '';
+        const offset = range.startOffset;
+        const atIdx = text.lastIndexOf('@', offset - 1);
+        if (atIdx >= 0) {
+          node.textContent = text.substring(0, atIdx) + text.substring(offset);
+          range.setStart(node, atIdx);
+          range.collapse(true);
+        }
+      }
+    }
+
     range.deleteContents();
 
     // Create mention span
@@ -184,21 +210,6 @@ export function PromptInput() {
     return () => document.removeEventListener('mousedown', handler);
   }, [showMentionPopup]);
 
-  // Compute available (un-mentioned) references
-  const getMentionedIds = () => {
-    const ids = new Set<string>();
-    const el = editorRef.current;
-    if (el) {
-      el.querySelectorAll('[data-ref-id]').forEach((span) => {
-        const id = (span as HTMLElement).dataset.refId;
-        if (id) ids.add(id);
-      });
-    }
-    return ids;
-  };
-  const mentionedIds = getMentionedIds();
-  const availableRefs = references.filter((r) => !mentionedIds.has(r.id));
-
   const isEmpty = !prompt.trim() && !editorHtml;
 
   return (
@@ -219,15 +230,15 @@ export function PromptInput() {
       />
 
       {/* Mention popup */}
-      {showMentionPopup && availableRefs.length > 0 && (
+      {showMentionPopup && references.length > 0 && (
         <div
           className={styles.mentionPopup}
           style={{ top: mentionPos.top, left: mentionPos.left }}
         >
-          <div className={styles.mentionHeader}>选择引用素材</div>
+          <div className={styles.mentionHeader}>可能@的内容</div>
-          {availableRefs.map((ref) => (
+          {references.map((ref, idx) => (
             <button
-              key={ref.id}
+              key={`${ref.id}-${idx}`}
               className={styles.mentionItem}
               onMouseDown={(e) => {
                 e.preventDefault();