Read Station Messages

What has landed in this place — its mailbox, newest first.

THE READ THAT MAKES A FORWARD REAL. channel_messages had no writer until forward and no reader until this, so a line handed to a desk was a row nobody could ever look at: the count on the rail knew about the ones still ASKING, and everything else was invisible. A delivery you cannot inspect is indistinguishable from one that never happened.

THE READER'S CEILING IS THE FILESYSTEM'S. Rows carry no directory to hide behind, so channels.stream filters on metadata->>'visibility' through the same ladder a file is masked by — the reason that key exists at all (runtime/channels.py, and the turn that once saw 71 other customers' transcripts).