MAX_
Highest unlock timestamp a vault may commit to: 0xFFFFFFFD (2106-02-07). Anything higher can never be claimed, because the uint32 walls stack twice. A claim is final only when its lockTime is STRICTLY below the chain-time cutoff (IsFinalTx, nexa src/consensus/tx_verify.cpp: nLockTime < nBlockTime), and the block that would confirm the claim must itself carry a uint32 timestamp STRICTLY above the previous block's median-time-past (the time-too-old rule, nexa src/validation/validation.cpp). With header times capped at 0xFFFFFFFF, the highest median any minable block can be checked against is 0xFFFFFFFE, so the highest commitment that can ever confirm is 0xFFFFFFFD. (nLockTime is also serialized as a uint32, so nothing above 0xFFFFFFFF encodes at all.)