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>

deploy/compose.yaml

@@ -175,6 +175,9 @@ services:
     environment:
       COORDINATOR_URL: http://node-api:3335
       NODE_TOKEN: ${NODE_TOKEN}
+      # The window worker (REBUILD.md design 1 and 5): a group per thread, the window's snapshot to the coordinator
+      # this often; the coordinator keeps them under SNAPSHOT_DIR (the spool's snapshots/ on bulk by default).
+      EDGE_SNAPSHOT_MINUTES: ${EDGE_SNAPSHOT_MINUTES:-30}
     stop_grace_period: 60s
     depends_on:
       node-api: