An "ancient" range a group: articles 1 … low watermark − 1, never filled

Every group is tiled from article 1 now: one range with status 'ancient'
covers what had expired on the server before the group was planned.
Nothing selects it (leases, prefetcher, corpus fill, tail merger all take
'planned'), the status panel reports it apart, the search's history stats
leave it out. Migration 6700 adds it for the groups planned before;
Planner.historyRows (now a pure function, unit-tested) for new groups.
The status bands are ordered by an explicit key: the ancient row at
priority 0 tied "history 0-999" with "window 0".

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

app/services/planner.ts

@@ -35,20 +35,8 @@ class Planner {
 
   async planGroup(group: { id: number; name: string }): Promise<number> {
     const info = await NntpPool.use((client) => client.group(group.name))
-    const size = coordinatorConfig.rangeArticles
     const last = await db.from('ranges').where('group_id', group.id).max('end_id as end').first()
-    const from = Math.max(info.low, Number(last?.end ?? 0) + 1)
-    const span = Math.max(1, info.high - info.low)
-    const rows = []
-    for (let start = from; start <= info.high; start += size) {
-      rows.push({
-        group_id: group.id,
-        start_id: start,
-        end_id: Math.min(start + size - 1, info.high),
-        next_id: start,
-        priority: Math.floor((1000 * (start - info.low)) / span),
-      })
-    }
+    const rows = historyRows(group.id, info, Number(last?.end ?? 0), coordinatorConfig.rangeArticles)
     for (let i = 0; i < rows.length; i += 2000) await db.table('ranges').multiInsert(rows.slice(i, i + 2000))
     await db.from('groups').where('id', group.id).update({ low: info.low, high: info.high, planned_at: new Date() })
     return rows.length
@@ -270,4 +258,34 @@ export function tailMerges(
   return merges
 }
 
+/**
+ * The rows a group's history is cut into, from `lastEnd + 1` (0: the group has no ranges yet) up to the high
+ * watermark: RANGE_ARTICLES slices at the position priority. A group planned for the first time also gets one
+ * "ancient" range, articles 1 … low − 1: what had expired on the server before it was planned. Status
+ * 'ancient', never leased or fetched; it keeps the tiling complete from article 1 (migration 6700 added it for
+ * the groups planned before 2026-10-28).
+ */
+export function historyRows(
+  groupId: number,
+  info: { low: number; high: number },
+  lastEnd: number,
+  size: number
+): Record<string, unknown>[] {
+  const rows: Record<string, unknown>[] = []
+  if (lastEnd === 0 && info.low > 1)
+    rows.push({ group_id: groupId, start_id: 1, end_id: info.low - 1, next_id: 1, priority: 0, status: 'ancient' })
+  const from = Math.max(info.low, lastEnd + 1)
+  const span = Math.max(1, info.high - info.low)
+  for (let start = from; start <= info.high; start += size) {
+    rows.push({
+      group_id: groupId,
+      start_id: start,
+      end_id: Math.min(start + size - 1, info.high),
+      next_id: start,
+      priority: Math.floor((1000 * (start - info.low)) / span),
+    })
+  }
+  return rows
+}
+
 export default new Planner()