Function decode_option_duration 

pub const fn decode_option_duration(encoded: u128) -> Option<Duration>

Decode an Option<Duration> from an encoded u128.

Accepts non-canonical input without panicking. The Some(_) encoding stores 64 bits of seconds in bits 32..=95 and up to 30 bits of nanoseconds in bits 0..=31 (bit 127 is the Some/None discriminant, bits 96..=126 are unused). If the decoded nanosecond count is 10⁹ or more — which encode_option_duration never produces, but which can appear when the encoded value comes from corrupted storage or untrusted input — the extra whole seconds are folded into the seconds field; if that push past u64::MAX, the result saturates at Duration::MAX.

This means decode_option_duration(u128::MAX) yields Some(Duration::MAX) rather than panicking as the previous implementation did.