Posting-time windows into the corpus: ranges:dates, ranges:capture

ranges:dates samples each active group's posting dates from the news
server (group_dates) and estimates every range's date (ranges.est_date).
ranges:capture --from --to marks a window's ranges of every group for the
corpus. The corpus fill takes capture ranges in priority order, done ones
too, and remembers complete ones (ranges.stored_at).

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

REBUILD.md

@@ -244,6 +244,20 @@ The worker makes the same releases of a filtered chunk; rule_counts lack
 those two rules' counts. `corpus:filter` filters chunks stored raw. A
 corpus filtered this way no longer serves a sweep of those two rules.
 
+Windows by posting time (2026-10-25; voyager 3's test data, LOG.md (104)):
+`ranges:dates` samples when each active group's articles were posted (one
+XOVER of 32 articles every 500M articles of the group, 16 … 1000 samples,
+the median Date of each slice, kept monotone; `group_dates`) and estimates
+every range's posting date from the curve (`ranges.est_date`; the edges of
+a window are off by up to one sample interval, three weeks in boneless).
+`ranges:capture --from 2025-01-01 --to 2026-01-01` marks every active
+group's ranges posted in the window `capture`: planned ones not started at
+`--priority` (0), done ones as they are, both fetched into the corpus by the
+fill, which takes capture ranges in priority order, done ones too (they're
+fetched again, corpus only), and skips those complete (`ranges.stored_at`,
+set when it sees the range.json). A year of every group is the data to
+replay voyager 3's 30-day blocks on.
+
 ## Phase 2
 
 Built: the prober (2026-10-11; `probe:run`, LOG.md 2026-10-11 (2)). It