diff --git a/core/hakmem_tiny_refill.inc.h b/core/hakmem_tiny_refill.inc.h
index 7588d4e9..6ab0637c 100644
--- a/core/hakmem_tiny_refill.inc.h
+++ b/core/hakmem_tiny_refill.inc.h
@@ -204,8 +204,8 @@ static inline int sll_refill_small_from_ss(int class_idx, int max_take) {
     TinySlabMeta* meta = tls->meta;
     if (!meta) return 0;
 
-    // Class7 special-case: simple batch refill (favor linear carve, minimal branching)
-    if (__builtin_expect(class_idx == 7, 0)) {
+    // Class 5/6/7 special-case: simple batch refill (favor linear carve, minimal branching)
+    if (__builtin_expect(class_idx >= 5, 0)) {
         uint32_t sll_cap = sll_cap_for_class(class_idx, (uint32_t)TINY_TLS_MAG_CAP);
         int room = (int)sll_cap - (int)g_tls_sll_count[class_idx];
         if (room <= 0) return 0;
diff --git a/core/tiny_superslab_alloc.inc.h b/core/tiny_superslab_alloc.inc.h
index 7031c515..b4afaaf0 100644
--- a/core/tiny_superslab_alloc.inc.h
+++ b/core/tiny_superslab_alloc.inc.h
@@ -133,6 +133,24 @@ static inline void* superslab_alloc_from_slab(SuperSlab* ss, int slab_idx) {
     return NULL;  // Slab is full
 }
 
+// Adopt helper: acquire → drain → bind (single boundary) – returns 1 on success
+static inline int adopt_bind_if_safe(TinyTLSSlab* tls, SuperSlab* ss, int slab_idx, int class_idx) {
+    uint32_t self_tid = tiny_self_u32();
+    SlabHandle h = slab_try_acquire(ss, slab_idx, self_tid);
+    if (!slab_is_valid(&h)) return 0;
+    slab_drain_remote_full(&h);
+    if (__builtin_expect(slab_is_safe_to_bind(&h), 1)) {
+        // Optional: move a few nodes to Front SLL to boost next hits
+        tiny_drain_freelist_to_sll_once(h.ss, h.slab_idx, class_idx);
+        tiny_tls_bind_slab(tls, h.ss, h.slab_idx);
+        // Ownership now associated with TLS slab; release handle bookkeeping
+        slab_release(&h);
+        return 1;
+    }
+    slab_release(&h);
+    return 0;
+}
+
 // Phase 6.24 & 7.6: Refill TLS SuperSlab (with unified TLS cache + deferred allocation)
 static SuperSlab* superslab_refill(int class_idx) {
 #if HAKMEM_DEBUG_COUNTERS
@@ -475,21 +493,11 @@ static SuperSlab* superslab_refill(int class_idx) {
             if (!ss || ss->magic != SUPERSLAB_MAGIC) continue;
             // Note: class_idx check is not needed (per-class registry!)
 
-            // Pick first slab with freelist (Box 4: 所有権取得 + remote check)
+            // Pick first slab with freelist (Box 4: adopt boundary helper)
             int reg_cap = ss_slabs_capacity(ss);
-            uint32_t self_tid = tiny_self_u32();
             for (int s = 0; s < reg_cap; s++) {
                 if (ss->slabs[s].freelist) {
-                    SlabHandle h = slab_try_acquire(ss, s, self_tid);
-                    if (slab_is_valid(&h)) {
-                        slab_drain_remote_full(&h);
-                        if (slab_is_safe_to_bind(&h)) {
-                            tiny_drain_freelist_to_sll_once(h.ss, h.slab_idx, class_idx);
-                            tiny_tls_bind_slab(tls, ss, s);
-                            return ss;
-                        }
-                        slab_release(&h);
-                    }
+                    if (adopt_bind_if_safe(tls, ss, s, class_idx)) return ss;
                 }
             }
         }