A null resetValue encoded to null, which wrote an empty string and then handed the
waiter a null target (= any change), fast-pathing on the stale cache and reinstating
the race the overload exists to close. The context parameter is now non-nullable and
the accessor throws ArgumentException before any write. Also: additive-timeout note on
all surfaces, batch-failure message no longer names the bool overload, and the
error-message/batch-failure branches are pinned.
Claude-Session: https://claude.ai/code/session_01XPsuy2ZZ5Gbyfpt8PrK5BV
The MES/Delmia handshake fast-paths on the previous run's cached CompleteFlag
because the reset write has not echoed back before the wait registers. An
edge-triggered wait is rejected (a subscription can swallow the reset when the
device flips inside one sampling interval); the fix encodes the reset leg inside
a new WriteBatchAndWaitAsync overload that observes the reset echo before writing
the trigger and returns a phase-aware HandshakeResult.
Claude-Session: https://claude.ai/code/session_01XPsuy2ZZ5Gbyfpt8PrK5BV