After a rollback, a record a newer build wrote (a new enum variant, a
changed required field) stopped decoding, and the strict
`schedules::read` turned that into an error on every read and write of
the key until someone deleted it by hand.
- agent_limits / inference (one document per agent): an undecodable
document reads as unset, with a WARN naming the bucket, key and error.
The PUT's "equal to stored, skip the write" shortcut no longer applies
to an undecodable document, so a PUT of the defaults replaces it too.
- schedule definitions (one document, every schedule): salvaged per
definition, as the review-classifier run list is. An undecodable
definition is kept as its raw JSON, hidden from the list, edits and
projections, written back by every commit after the readable ones, and
its id is never minted again. A document with no list of schedules
stays an error: reading it as empty would empty every agent's key.
- per-agent agent-schedules: an undecodable key reads as no schedules
and is rewritten on the next projection, even when the agent has none.
`schedules::read` is replaced by `read_or_default`; `wanted` keeps its
own strict read.
Closes#5193
29aa242201