perf(index): debounce lexical warmup after invalidation paths

modules/story-summary/story-summary.js

@@ -173,6 +173,8 @@ function onSendKeydown(e) {
 
 let hideApplyTimer = null;
 const HIDE_APPLY_DEBOUNCE_MS = 250;
+let lexicalWarmupTimer = null;
+const LEXICAL_WARMUP_DEBOUNCE_MS = 500;
 
 const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
 
@@ -358,6 +360,7 @@ async function handleAnchorGenerate() {
         // L1 rebuild only if new chunks were added (usually 0 in normal chat)
         if (chunkResult.built > 0) {
             invalidateLexicalIndex();
+            scheduleLexicalWarmup();
         }
 
         await sendAnchorStatsToFrame();
@@ -623,6 +626,7 @@ async function maybeAutoExtractL0() {
         // L1 rebuild only if new chunks were added
         if (chunkResult.built > 0) {
             invalidateLexicalIndex();
+            scheduleLexicalWarmup();
         }
 
         await sendAnchorStatsToFrame();
@@ -1003,6 +1007,16 @@ function applyHideStateDebounced() {
     }, HIDE_APPLY_DEBOUNCE_MS);
 }
 
+function scheduleLexicalWarmup(delayMs = LEXICAL_WARMUP_DEBOUNCE_MS) {
+    clearTimeout(lexicalWarmupTimer);
+    const scheduledChatId = getContext().chatId || null;
+    lexicalWarmupTimer = setTimeout(() => {
+        lexicalWarmupTimer = null;
+        if (isChatStale(scheduledChatId)) return;
+        warmupIndex();
+    }, delayMs);
+}
+
 async function clearHideState() {
     // 暴力全量 unhide，确保立刻恢复
     await unhideAllMessages();
@@ -1424,6 +1438,7 @@ async function handleMessageDeleted(scheduledChatId) {
     }
 
     invalidateLexicalIndex();
+    scheduleLexicalWarmup();
     await sendAnchorStatsToFrame();
     await sendVectorStatsToFrame();
 
@@ -1673,6 +1688,8 @@ function unregisterEvents() {
     events.cleanup();
     events = null;
     activeChatId = null;
+    clearTimeout(lexicalWarmupTimer);
+    lexicalWarmupTimer = null;
 
     $(".xiaobaix-story-summary-btn").remove();
     hideOverlay();