diff --git a/core/box/mailbox_box.d b/core/box/mailbox_box.d
index ee5eec23..f2496cc1 100644
--- a/core/box/mailbox_box.d
+++ b/core/box/mailbox_box.d
@@ -6,7 +6,8 @@ core/box/mailbox_box.o: core/box/mailbox_box.c core/box/mailbox_box.h \
  core/superslab/../hakmem_tiny_config.h core/tiny_debug_ring.h \
  core/hakmem_build_flags.h core/tiny_remote.h \
  core/hakmem_tiny_superslab_constants.h core/hakmem_tiny.h \
- core/hakmem_trace.h core/hakmem_tiny_mini_mag.h core/tiny_debug_ring.h
+ core/hakmem_trace.h core/hakmem_tiny_mini_mag.h \
+ core/hakmem_trace_master.h core/tiny_debug_ring.h
 core/box/mailbox_box.h:
 core/hakmem_tiny_superslab.h:
 core/superslab/superslab_types.h:
@@ -23,4 +24,5 @@ core/hakmem_tiny_superslab_constants.h:
 core/hakmem_tiny.h:
 core/hakmem_trace.h:
 core/hakmem_tiny_mini_mag.h:
+core/hakmem_trace_master.h:
 core/tiny_debug_ring.h:
diff --git a/core/box/pool_api.inc.h b/core/box/pool_api.inc.h
index dd659a8f..b956b397 100644
--- a/core/box/pool_api.inc.h
+++ b/core/box/pool_api.inc.h
@@ -307,9 +307,32 @@ void hak_pool_free(void* ptr, size_t size, uintptr_t site_id) {
         if (same_thread) {
             PoolTLSRing* ring = &g_tls_bin[class_idx].ring;
             if (g_tls_ring_enabled && ring->top < POOL_L2_RING_CAP) { ring->items[ring->top++] = block; }
-            else { block->next = g_tls_bin[class_idx].lo_head; g_tls_bin[class_idx].lo_head = block; g_tls_bin[class_idx].lo_count++; if ((int)g_tls_bin[class_idx].lo_count > g_tls_lo_max) {
-                    size_t spill = g_tls_bin[class_idx].lo_count / 2; int shard = hak_pool_get_shard_index(site_id);
-                    while (spill-- && g_tls_bin[class_idx].lo_head) { PoolBlock* b = g_tls_bin[class_idx].lo_head; g_tls_bin[class_idx].lo_head = b->next; g_tls_bin[class_idx].lo_count--; HKM_TIME_START(t_remote_push1); uintptr_t old_head; do { old_head = atomic_load_explicit(&g_pool.remote_head[class_idx][shard], memory_order_acquire); b->next = (PoolBlock*)old_head; } while (!atomic_compare_exchange_weak_explicit(&g_pool.remote_head[class_idx][shard], &old_head, (uintptr_t)b, memory_order_release, memory_order_relaxed)); atomic_fetch_add_explicit(&g_pool.remote_count[class_idx][shard], 1, memory_order_relaxed); HKM_TIME_END(HKM_CAT_POOL_REMOTE_PUSH, t_remote_push1); } set_nonempty_bit(class_idx, shard); } }
+            else {
+                block->next = g_tls_bin[class_idx].lo_head;
+                g_tls_bin[class_idx].lo_head = block;
+                g_tls_bin[class_idx].lo_count++;
+                if ((int)g_tls_bin[class_idx].lo_count > g_tls_lo_max) {
+                    size_t spill = g_tls_bin[class_idx].lo_count / 2;
+                    int shard = hak_pool_get_shard_index(site_id);
+                    // Spill half of local freelist to remote freelist
+                    while (spill-- && g_tls_bin[class_idx].lo_head) {
+                        PoolBlock* b = g_tls_bin[class_idx].lo_head;
+                        g_tls_bin[class_idx].lo_head = b->next;
+                        g_tls_bin[class_idx].lo_count--;
+                        HKM_TIME_START(t_remote_push1);
+                        uintptr_t old_head;
+                        do {
+                            old_head = atomic_load_explicit(&g_pool.remote_head[class_idx][shard], memory_order_acquire);
+                            b->next = (PoolBlock*)old_head;
+                        } while (!atomic_compare_exchange_weak_explicit(&g_pool.remote_head[class_idx][shard],
+                                                                         &old_head, (uintptr_t)b,
+                                                                         memory_order_release, memory_order_relaxed));
+                        atomic_fetch_add_explicit(&g_pool.remote_count[class_idx][shard], 1, memory_order_relaxed);
+                        HKM_TIME_END(HKM_CAT_POOL_REMOTE_PUSH, t_remote_push1);
+                    }
+                    set_nonempty_bit(class_idx, shard);
+                }
+            }
         } else {
             if (g_tc_enabled) { uint64_t owner_tid = 0; if (g_hdr_light_enabled < 2) owner_tid = hdr->owner_tid; if (owner_tid == 0) { MidPageDesc* d = mid_desc_lookup(raw); if (d) owner_tid = d->owner_tid; } if (owner_tid != 0) { MidTC* otc = mid_tc_lookup_by_tid(owner_tid); if (otc) { mid_tc_push(otc, class_idx, block); return; } } }
             int shard = hak_pool_get_shard_index(site_id); uintptr_t old_head; HKM_TIME_START(t_remote_push2);
diff --git a/hakmem_elo.d b/hakmem_elo.d
index 70e18062..8154d31c 100644
--- a/hakmem_elo.d
+++ b/hakmem_elo.d
@@ -1,7 +1,9 @@
-hakmem_elo.o: core/hakmem_elo.c core/hakmem_elo.h core/hakmem_internal.h \
- core/hakmem.h core/hakmem_build_flags.h core/hakmem_config.h \
- core/hakmem_features.h core/hakmem_sys.h core/hakmem_whale.h
+hakmem_elo.o: core/hakmem_elo.c core/hakmem_elo.h \
+ core/hakmem_debug_master.h core/hakmem_internal.h core/hakmem.h \
+ core/hakmem_build_flags.h core/hakmem_config.h core/hakmem_features.h \
+ core/hakmem_sys.h core/hakmem_whale.h
 core/hakmem_elo.h:
+core/hakmem_debug_master.h:
 core/hakmem_internal.h:
 core/hakmem.h:
 core/hakmem_build_flags.h:
diff --git a/hakmem_shared_pool.d b/hakmem_shared_pool.d
index 8d572a04..10f3b7e2 100644
--- a/hakmem_shared_pool.d
+++ b/hakmem_shared_pool.d
@@ -5,7 +5,8 @@ hakmem_shared_pool.o: core/hakmem_shared_pool.c core/hakmem_shared_pool.h \
  core/superslab/../hakmem_tiny_superslab_constants.h \
  core/superslab/../hakmem_tiny_config.h core/tiny_debug_ring.h \
  core/hakmem_build_flags.h core/tiny_remote.h \
- core/hakmem_tiny_superslab_constants.h core/box/ss_slab_meta_box.h \
+ core/hakmem_tiny_superslab_constants.h core/hakmem_debug_master.h \
+ core/hakmem_stats_master.h core/box/ss_slab_meta_box.h \
  core/box/../superslab/superslab_types.h core/box/slab_freelist_atomic.h \
  core/box/tiny_next_ptr_box.h core/hakmem_tiny_config.h \
  core/tiny_nextptr.h core/tiny_region_id.h core/tiny_box_geometry.h \
@@ -19,7 +20,7 @@ hakmem_shared_pool.o: core/hakmem_shared_pool.c core/hakmem_shared_pool.h \
  core/box/../ptr_track.h core/box/../ptr_trace.h \
  core/box/../tiny_debug_ring.h core/box/../superslab/superslab_inline.h \
  core/box/free_local_box.h core/hakmem_tiny_superslab.h \
- core/hakmem_policy.h
+ core/box/tls_slab_reuse_guard_box.h core/hakmem_policy.h
 core/hakmem_shared_pool.h:
 core/superslab/superslab_types.h:
 core/hakmem_tiny_superslab_constants.h:
@@ -33,6 +34,8 @@ core/tiny_debug_ring.h:
 core/hakmem_build_flags.h:
 core/tiny_remote.h:
 core/hakmem_tiny_superslab_constants.h:
+core/hakmem_debug_master.h:
+core/hakmem_stats_master.h:
 core/box/ss_slab_meta_box.h:
 core/box/../superslab/superslab_types.h:
 core/box/slab_freelist_atomic.h:
@@ -62,4 +65,5 @@ core/box/../tiny_debug_ring.h:
 core/box/../superslab/superslab_inline.h:
 core/box/free_local_box.h:
 core/hakmem_tiny_superslab.h:
+core/box/tls_slab_reuse_guard_box.h:
 core/hakmem_policy.h:
diff --git a/hakmem_tiny_sfc.d b/hakmem_tiny_sfc.d
index 992a436e..8695e7da 100644
--- a/hakmem_tiny_sfc.d
+++ b/hakmem_tiny_sfc.d
@@ -7,8 +7,8 @@ hakmem_tiny_sfc.o: core/hakmem_tiny_sfc.c core/tiny_alloc_fast_sfc.inc.h \
  core/hakmem_tiny_superslab.h core/superslab/superslab_types.h \
  core/hakmem_tiny_superslab_constants.h core/superslab/superslab_inline.h \
  core/superslab/superslab_types.h core/superslab/../tiny_box_geometry.h \
- core/tiny_debug_ring.h core/tiny_remote.h core/tiny_tls.h \
- core/box/tls_sll_box.h core/box/../hakmem_tiny_config.h \
+ core/tiny_debug_ring.h core/tiny_remote.h core/hakmem_stats_master.h \
+ core/tiny_tls.h core/box/tls_sll_box.h core/box/../hakmem_tiny_config.h \
  core/box/../hakmem_build_flags.h core/box/../tiny_remote.h \
  core/box/../tiny_region_id.h core/box/../hakmem_tiny_integrity.h \
  core/box/../hakmem_tiny.h core/box/../ptr_track.h \
@@ -36,6 +36,7 @@ core/superslab/superslab_types.h:
 core/superslab/../tiny_box_geometry.h:
 core/tiny_debug_ring.h:
 core/tiny_remote.h:
+core/hakmem_stats_master.h:
 core/tiny_tls.h:
 core/box/tls_sll_box.h:
 core/box/../hakmem_tiny_config.h:
diff --git a/verify_fix_20runs.sh b/verify_fix_20runs.sh
new file mode 100755
index 00000000..2e55b634
--- /dev/null
+++ b/verify_fix_20runs.sh
@@ -0,0 +1,157 @@
+#!/bin/bash
+
+# Destructor Crash Fix Verification Script
+# Purpose: Run 20 development build benchmarks to verify crash fix
+# Expected: 0% crash rate (previously 50%)
+
+echo "========================================="
+echo "Destructor Crash Fix Verification"
+echo "========================================="
+echo "Target: 20 successful runs"
+echo "Build Mode: Development (HAKMEM_BUILD_RELEASE=0)"
+echo "Expected Performance: ~30.7M ops/s"
+echo ""
+
+# Ensure we're in development build mode
+export HAKMEM_BUILD_RELEASE=0
+
+# Arrays to store results
+declare -a throughputs
+declare -a statuses
+total_runs=20
+success_count=0
+crash_count=0
+
+echo "Starting 20-run verification test..."
+echo ""
+
+for i in $(seq 1 $total_runs); do
+    echo "========================================="
+    echo "Run $i/$total_runs"
+    echo "========================================="
+
+    # Run the benchmark and capture output and exit code
+    output=$(./larson_hakmem 1 10 1 1000 100 10000 42 2>&1)
+    exit_code=$?
+
+    # Check if benchmark completed successfully
+    if echo "$output" | grep -q "Throughput" && [ $exit_code -eq 0 ]; then
+        # Extract throughput value
+        throughput=$(echo "$output" | grep "Throughput" | awk '{print $3}')
+        throughputs+=("$throughput")
+        statuses+=("SUCCESS")
+        success_count=$((success_count + 1))
+        echo "✓ SUCCESS: $throughput ops/s"
+    else
+        throughputs+=("0")
+        statuses+=("CRASH")
+        crash_count=$((crash_count + 1))
+        echo "✗ CRASHED (exit code: $exit_code)"
+        echo "Last few lines of output:"
+        echo "$output" | tail -5
+    fi
+
+    echo ""
+    sleep 1  # Brief pause between runs
+done
+
+echo ""
+echo "========================================="
+echo "FINAL RESULTS SUMMARY"
+echo "========================================="
+echo ""
+echo "Execution Statistics:"
+echo "  Total Runs:      $total_runs"
+echo "  Successful:      $success_count"
+echo "  Crashed:         $crash_count"
+echo "  Success Rate:    $(awk "BEGIN {printf \"%.1f%%\", ($success_count/$total_runs)*100}")"
+echo "  Crash Rate:      $(awk "BEGIN {printf \"%.1f%%\", ($crash_count/$total_runs)*100}")"
+echo ""
+
+if [ $success_count -gt 0 ]; then
+    echo "Performance Statistics (Successful Runs):"
+
+    # Calculate mean
+    sum=0
+    for tp in "${throughputs[@]}"; do
+        if [ "$tp" != "0" ]; then
+            sum=$(awk "BEGIN {print $sum + $tp}")
+        fi
+    done
+    mean=$(awk "BEGIN {printf \"%.2f\", $sum/$success_count}")
+    echo "  Mean:            $mean M ops/s"
+
+    # Calculate min and max
+    min=999999999
+    max=0
+    for tp in "${throughputs[@]}"; do
+        if [ "$tp" != "0" ]; then
+            if (( $(awk "BEGIN {print ($tp < $min)}") )); then
+                min=$tp
+            fi
+            if (( $(awk "BEGIN {print ($tp > $max)}") )); then
+                max=$tp
+            fi
+        fi
+    done
+    echo "  Min:             $min M ops/s"
+    echo "  Max:             $max M ops/s"
+    echo "  Range:           $(awk "BEGIN {printf \"%.2f\", $max - $min}") M ops/s"
+
+    # Calculate standard deviation
+    variance=0
+    for tp in "${throughputs[@]}"; do
+        if [ "$tp" != "0" ]; then
+            diff=$(awk "BEGIN {print $tp - $mean}")
+            variance=$(awk "BEGIN {print $variance + ($diff * $diff)}")
+        fi
+    done
+    variance=$(awk "BEGIN {print $variance / $success_count}")
+    stddev=$(awk "BEGIN {printf \"%.2f\", sqrt($variance)}")
+    echo "  Std Deviation:   $stddev M ops/s"
+
+    # Calculate coefficient of variation
+    cv=$(awk "BEGIN {printf \"%.2f%%\", ($stddev/$mean)*100}")
+    echo "  Variation:       $cv"
+
+    # Compare to expected performance
+    expected=30.7
+    deviation=$(awk "BEGIN {printf \"%.2f%%\", (($mean - $expected)/$expected)*100}")
+    echo ""
+    echo "Comparison to Phase 4a Baseline (30.7M ops/s):"
+    echo "  Deviation:       $deviation"
+fi
+
+echo ""
+echo "Detailed Run-by-Run Results:"
+echo "Run#  Status   Throughput (M ops/s)"
+echo "----  -------  -------------------"
+for i in $(seq 0 $((total_runs - 1))); do
+    status="${statuses[$i]}"
+    tp="${throughputs[$i]}"
+    if [ "$tp" == "0" ]; then
+        printf "%-4d  %-7s  %s\n" $((i + 1)) "$status" "N/A"
+    else
+        printf "%-4d  %-7s  %s\n" $((i + 1)) "$status" "$tp"
+    fi
+done
+
+echo ""
+echo "========================================="
+echo "VERIFICATION CONCLUSION"
+echo "========================================="
+if [ $crash_count -eq 0 ]; then
+    echo "✓ PASS: No crashes detected in 20 runs"
+    echo "  Previous crash rate: 50%"
+    echo "  Current crash rate:  0%"
+    echo "  Improvement: 100% crash elimination"
+else
+    echo "✗ FAIL: Crashes still occurring"
+    echo "  Expected: 0 crashes"
+    echo "  Actual:   $crash_count crashes"
+    echo "  This indicates the fix may be incomplete"
+fi
+
+echo ""
+echo "Test completed at $(date)"
+echo "========================================="