Partial update. Keys omitted from the request body are left unchanged; send a key with a
null, empty, or whitespace-only value to clear it. Prefer this over
update-contract-metadata when setting or clearing individual keys, as it cannot disturb
keys you did not name. Archived keys may only be cleared, never changed. Every key must
name a definition assigned to contracts: an unknown key, or one assigned only to another
entity type, fails the request with a 400. Keys are never silently ignored. The write is
atomic: if any key fails validation, nothing is written.
A matching contract "Edit or amend" approval rule holds the change: the request answers 202 with the approval request, and the
contract keeps its values until the request is approved. While another change to the contract waits for approval, the request
is refused.