process.ConsumerLedger writes stream, name, acknowledged sequence, pending, last event applied with its at and the delivery of
the oldest unacknowledged message into one key per consumer, after each message delivered and applied, so a tool reads them.
Builds: design 47 G §579, A-166, A-176
Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h