=== BUILD OK ===
Layout: h[9] (idx 0..8), canary at &h[9]
MEMO_CLUSTER_SIZE = 4096
A=0x8004ae000  B=0x8004af000  (B == A ^ 4096 = buddy pair)
freed A: parked on h[8] (s=4096)
freed B: entering merge loop at i=8, s=4096
  merged at i=8 -> new i=9, s=8192

*** OOB WRITE at h[9] -- canary corrupted ***
    (kernel: `q = &h[9]` then `h[9].next = (m_link_s*)a`
     = 8-byte write past m_pool_s.h[] into adjacent heap)
    canary before = 0xdeadbeefcafebabe
    canary after  = 0x00000008004ae000  (OVERWRITTEN)
RUN_EXIT=0