v21.1.0

A minor release. The brain format (version: 8), the reply schemas, the queue format and the search cache are unchanged; bf.yaml accepts one more form, so no upgrade step is needed.

Added

• Retries by run kind. An assistant's idempotent accepts a list of run kinds besides true and false, such as [schedule, wake]: a failed or interrupted attempt of a listed kind retries by itself with backoff, while other runs, such as an answer to a message that may have acted, wait for bf queue ID --retry or --cancel (what a run records).