ACI-059: The Whiteboard

Thesis

A fleet's whiteboard is four invariants: every board has one writer, each per-sender inbox has one appender (its sender) and one clearer (its owner), a hold names the condition that releases it, and a stamp is read from a clock. On Intent 3 each board is a view generated from a store and changed only through intent wb, and the service reads every stamp from its own clock. The writer rule is still a convention, because --node names whichever node the caller says. One writer per board prevents contention but not growth, so each board is also its node's restart file, folded before every compaction.