The window worker: group leases, the stream serving the corpus, the snapshot through the API (design 1 and 5)

A worker thread leases a group and takes its ranges in article order through
one carried window; the coordinator keeps one cursor a group (group_leases,
migration 6500) and hands out the next range, the rules and nothing about
where the chunks are: the range stream serves a stored range's chunks from the
corpus file and a live one's from the spool. The window's snapshot (bincode:
the frontier, the open files, releases and albums, the upload numbers, the
batch-counter table) goes to the coordinator every EDGE_SNAPSHOT_MINUTES and
when the group is given back, and the next holder restores it; a takeover
after LEASE_TTL_SECONDS plans the ranges from the snapshot's article again.
The prefetcher runs ahead of held groups' cursors and skips chunks the corpus
has. LEASE_MIN_PRIORITY..LEASE_MAX_PRIORITY bound what is leased. edge-node
holds groups by default; --ranges keeps the old per-range path.

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

config/coordinator.ts

@@ -31,6 +31,13 @@ export default {
   },
   /** A leased range without a heartbeat for this long goes back to the queue. */
   leaseTtlSeconds: env.get('LEASE_TTL_SECONDS', 15 * 60),
+  /**
+   * The ranges group leases hand out (REBUILD.md design 1), by priority: the tail is negative, the capture windows
+   * 0–2 (2016, 2021, 2025), the rest of the history above (its position in the group, or 4000+). Bounds so a
+   * deployment can run one window first (homelab 2026-10-26: 0..0, the 2016 window); unbounded by default.
+   */
+  leasePriorityMin: env.get('LEASE_MIN_PRIORITY', -1_000_000),
+  leasePriorityMax: env.get('LEASE_MAX_PRIORITY', 1_000_000),
   /** NNTP connections the coordinator fetches headers with: at most (its share, nntpShares), and at least while sharing. */
   nntpConnections: env.get('NNTP_CONNECTIONS', 4),
   nntpMinConnections: env.get('NNTP_MIN_CONNECTIONS', 8),
@@ -146,6 +153,11 @@ export default {
      */
     filter: env.get('CORPUS_FILTER', true),
   },
+  /**
+   * The group windows' snapshots (REBUILD.md, "Voyager 3: window indexing", 5; app/services/group_leases.ts): a
+   * file a group on bulk, next to the spool by default.
+   */
+  snapshotDir: env.get('SNAPSHOT_DIR', `${env.get('SPOOL_DIR', app.tmpPath('spool'))}/snapshots`),
   spool: {
     dir: env.get('SPOOL_DIR', app.tmpPath('spool')),
     /** Ranges kept fetched ahead, per active lease. */