- Reject a control line that does not start with "{", so another
release's length-prefixed frame fails as a protocol error instead of
waiting for a newline until the deadline.
- Bump SSH_PROTOCOL_VERSION to 3: executable helpers embed the PTC
worker, so an older helper is now rejected while connecting.
- Send a small error instead of a late binding result from a finished
persistent evaluation, so it cannot overflow the pipe shared with
the next evaluation.
- Leave per-call binding waits pending after the result instead of
rejecting them; unawaited calls crashed the child and leaked the
trace into the result logs.
- Pin birpc to 4.2.0 so the host and the bundled child agree, and
regenerate THIRD_PARTY_NOTICES.md.
- Update stale frame wording.