Restore C7 Warm/TLS carve for release and add policy scaffolding

core/box/tiny_class_stats_box.h

@@ -0,0 +1,42 @@
+// tiny_class_stats_box.h - Lightweight per-thread class stats (OBSERVE layer)
+//
+// Purpose:
+//   - Provide per-class counters without atomics for cheap observation.
+//   - Hot paths call small inline helpers; aggregation/printing can be added later.
+
+#ifndef TINY_CLASS_STATS_BOX_H
+#define TINY_CLASS_STATS_BOX_H
+
+#include <stdint.h>
+#include "../hakmem_tiny_config.h"
+
+typedef struct TinyClassStatsThread {
+    uint64_t uc_miss[TINY_NUM_CLASSES];    // unified_cache_refill() hits
+    uint64_t warm_hit[TINY_NUM_CLASSES];   // warm pool successes
+    uint64_t shared_lock[TINY_NUM_CLASSES]; // shared pool lock acquisitions (hook as needed)
+} TinyClassStatsThread;
+
+extern __thread TinyClassStatsThread g_tiny_class_stats;
+
+static inline void tiny_class_stats_on_uc_miss(int ci) {
+    if (ci >= 0 && ci < TINY_NUM_CLASSES) {
+        g_tiny_class_stats.uc_miss[ci]++;
+    }
+}
+
+static inline void tiny_class_stats_on_warm_hit(int ci) {
+    if (ci >= 0 && ci < TINY_NUM_CLASSES) {
+        g_tiny_class_stats.warm_hit[ci]++;
+    }
+}
+
+static inline void tiny_class_stats_on_shared_lock(int ci) {
+    if (ci >= 0 && ci < TINY_NUM_CLASSES) {
+        g_tiny_class_stats.shared_lock[ci]++;
+    }
+}
+
+// Optional: reset per-thread counters (cold path only).
+void tiny_class_stats_reset_thread(void);
+
+#endif // TINY_CLASS_STATS_BOX_H