[parent] created /tmp/updater_toctou_hLoz6R/download.crx (fd=3)
[child ] dup'd writable fd -> 5 (retained across rename)
[child ] wrote GOOD payload, signalling download complete
[parent] rename() -> /tmp/updater_toctou_hLoz6R/cache_hash.crx (inode=63236018)
[parent] Verify()  read: "GOOD-SIGNED-CRX-PAYLOAD-0123456789-0123456789-0123456789"
[parent] Verify()  result: OK_FULL
[child ] parent finished verify -> overwriting via retained fd
[parent] Unzip()   read: "MALICIOUS-PAYLOAD-OVERWRITTEN-BY-NET-WORKER-AFTER-VERIFY"

*** TOCTOU PRIMITIVE CONFIRMED ***
*** Verify saw GOOD; Unzip saw MALICIOUS via retained FD ***