diff --git a/libsuicmez/suicmez_gc.h b/libsuicmez/suicmez_gc.h
index e21149d..274c9da 100644
--- a/libsuicmez/suicmez_gc.h
+++ b/libsuicmez/suicmez_gc.h
@@ -15,6 +15,8 @@
 /* Forward declare Obj so ObjHeader can reference it */
 typedef struct Obj Obj;
 
+typedef struct TypeInfo TypeInfo;
+
 /* Header must come first */
 typedef struct ObjHeader {
     uint32_t size;        // total object size incl header
@@ -24,11 +26,11 @@ typedef struct ObjHeader {
     const TypeInfo *type;
 } ObjHeader;
 
-typedef struct TypeInfo {
+struct TypeInfo {
     uint16_t field_count;
     uint16_t pointer_count;
     const uint8_t *pointer_bitmap;
-} TypeInfo;
+};
 
 /* Full object definition */
 struct Obj {
@@ -44,7 +46,7 @@ void gc_init(void);
 void gc_shutdown(void);
 
 // Allocate object in young generation
-void* gc_alloc(size_t size);
+void *gc_alloc(const TypeInfo *type, size_t payload_size);
 
 // Root management
 void gc_add_root(void **ptr);
@@ -56,7 +58,13 @@ void gc_write_barrier(void *src, void *dst);
 // Minor GC slice (incremental)
 void gc_minor_collect_slice(size_t max_objects);
 
-// Trigger major GC (async background)
+// Trigger major GC
 void gc_major_collect(void);
 
+static inline void scan_object_fields(Obj *obj);
+
+static void mark_obj(Obj *obj);
+
+void gc_collect_old(void);
+
 #endif // SUICMEZ_GC_H
\ No newline at end of file