refactor: tighten audit-pass leak fixes

- store.ts softDeleteDesign: skip Set clone + set() when id not in
  autoPolishFired, so subscribers aren't notified on a no-op delete
- DesignCardPreview readCache: route hit path through memCacheTouch
  instead of duplicating delete+set inline
- overlay.ts: drop the redundant if (__cs_reattach_interval) guard
  before clearInterval — clearInterval is safe on undefined/0

Review follow-up to 6b8cfbc; runtime tests 15/15, desktop typecheck clean.

Author: hqhq1025

apps/desktop/src/renderer/src/store.ts

@@ -1679,9 +1679,11 @@ export const useCodesignStore = create<CodesignState>((set, get) => ({
     }
     try {
       await window.codesign.snapshots.softDeleteDesign(id);
-      const nextFired = new Set(get().autoPolishFired);
-      nextFired.delete(id);
-      set({ autoPolishFired: nextFired });
+      if (get().autoPolishFired.has(id)) {
+        const nextFired = new Set(get().autoPolishFired);
+        nextFired.delete(id);
+        set({ autoPolishFired: nextFired });
+      }
       const wasCurrent = get().currentDesignId === id;
       await get().loadDesigns();
       if (wasCurrent) {

apps/desktop/src/renderer/src/views/hub/DesignCardPreview.tsx

@@ -56,8 +56,8 @@ function cacheKey(id: string, updatedAt: string): string {
   return `${id}:${updatedAt}`;
 }
 
-// Map iteration order = insertion order, so delete+set on hit refreshes recency
-// and evicting the first key drops the least-recently-used entry.
+// Map preserves insertion order, so delete+set on access makes the eviction
+// loop drop the least-recently-used key when the cache overflows.
 function memCacheTouch(key: string, value: string): void {
   memCache.delete(key);
   memCache.set(key, value);
@@ -71,8 +71,7 @@ function memCacheTouch(key: string, value: string): void {
 function readCache(key: string): string | null {
   const hit = memCache.get(key);
   if (hit !== undefined) {
-    memCache.delete(key);
-    memCache.set(key, hit);
+    memCacheTouch(key, hit);
     return hit;
   }
   if (typeof localStorage === 'undefined') return null;

packages/runtime/src/overlay.ts

@@ -208,20 +208,13 @@ export const OVERLAY_SCRIPT = `(function() {
   }
   reattach();
   try {
-    if (window.__cs_reattach_interval) {
-      try { clearInterval(window.__cs_reattach_interval); } catch (_) {}
-      window.__cs_reattach_interval = 0;
-    }
+    try { clearInterval(window.__cs_reattach_interval); } catch (_) {}
     window.__cs_reattach_interval = setInterval(reattach, 200);
     if (!window.__cs_reattach_unload) {
       window.__cs_reattach_unload = true;
       var stopReattach = function() {
-        try {
-          if (window.__cs_reattach_interval) {
-            clearInterval(window.__cs_reattach_interval);
-            window.__cs_reattach_interval = 0;
-          }
-        } catch (_) {}
+        try { clearInterval(window.__cs_reattach_interval); } catch (_) {}
+        window.__cs_reattach_interval = 0;
       };
       try { window.addEventListener('pagehide', stopReattach, false); } catch (_) {}
       try { window.addEventListener('beforeunload', stopReattach, false); } catch (_) {}