The range stream polls the corpus as well as the spool while it waits

The corpus fill claims chunks of a leased range ahead of the leased run (the
prefetcher's claim keys are per range and chunk), stores them in the corpus
only, and the run leaves them there. The stream looked at the corpus once per
chunk and then polled the spool only: when the store came seconds after that
look, the stream waited its whole hour and the worker lost the group and its
open batch (three groups on 2026-10-27, LOG.md (118)). Now the wait loop checks
both.

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

REBUILD.md

@@ -551,6 +551,13 @@ releases, a third of them one poster's image dump (27.7 M rows, LOG.md
    when the window was marked, planned again by the reset): hence
    `LEASE_CAPTURE_ONLY` (the lease, next and the prefetcher's run-ahead
    take capture ranges only) and the one-off repair of the priorities.
+   The stream polls the corpus as well as the spool while it waits for a
+   chunk: the corpus fill claims chunks of the same range ahead of the
+   leased run (the prefetcher's claims are per range and chunk), stores
+   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).
 
 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