The edge posts the open batch before a failed stream gives the group back

A plain stop and a chunk that doesn't inflate already posted the batch so far,
so the stop snapshot stood at a stored resume point; a failed stream (the
stalled one's "Peer disconnected") skipped the post, left the batch open and
lost the window with the snapshot refused. Now only a batch the coordinator
refused stays open.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

REBUILD.md

@@ -557,7 +557,10 @@ releases, a third of them one poster's image dump (27.7 M rows, LOG.md
    them in the corpus only, and the run leaves them there; a stream that
    looked at the corpus once, seconds before that store, waited its whole
    hour on the spool and the worker lost the group and its open batch
-   (three groups on the first morning).
+   (three groups on the first morning). A failed stream now posts the
+   open batch before the group goes back, like a stop does, so the
+   window's snapshot survives it; only a batch the coordinator refused
+   (lease lost, too large) still loses the window.
 
 6. **The corpus stays as it is.** Measured on 300 unfiltered chunks
    (30 M lines, LOG.md (102)): 43% of lines lack a "(k/N)" counter, and of