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>

edge/Cargo.toml

@@ -14,6 +14,7 @@ path = "src/bin/edge-node.rs"
 
 [dependencies]
 base64 = "0.22"
+bincode = "1.3"
 chrono = "0.4"
 flate2 = { version = "1", default-features = false, features = ["zlib-rs"] }
 libdeflater = "1.26.1"