NNTP shares: the account's connections shared by priority

The coordinator (38) and the prober (8) had a fixed split; with history
paused the coordinator's stood idle while the prober's were its limit.
nntp_shares: each process syncs every 15 s (priority, minimum, what it could
use, what it has open) and gets what it may open: minimums first, then by
priority what each wants, growing only into connections the others closed
or gave up. The pool's size and the prober's lanes follow the grant; the
coordinator doubles its want while work waits for a connection, else asks
for its peak in use and a margin; the prober wants its maximum unless the
queue is dry. Claims scale with the lanes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

config/coordinator.ts

@@ -31,8 +31,21 @@ export default {
   },
   /** A leased range without a heartbeat for this long goes back to the queue. */
   leaseTtlSeconds: env.get('LEASE_TTL_SECONDS', 15 * 60),
-  /** NNTP connections the coordinator fetches headers with. */
+  /** 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),
+  /**
+   * The account's connections, shared by the coordinator and the prober by priority (app/services/nntp_shares.ts):
+   * all of them less the reserved ones (the spotter's and the spot inspector's 1 each, the coordinator's plain one,
+   * and 2 for a hedged request's or a reconnect's new connection while the old one closes).
+   */
+  nntpShares: {
+    total: env.get('NNTP_ACCOUNT_CONNECTIONS', 50) - env.get('NNTP_RESERVED_CONNECTIONS', 5),
+    everyMs: 15_000,
+    /** Headers before probes: history takes what it can use, the prober the rest. */
+    coordinatorPriority: 2,
+    proberPriority: 1,
+  },
   /**
    * A reply with no data for this long fails, and its connection is replaced.
    * Eweka sometimes stops answering on long-lived connections (all 40 quiet,
@@ -70,11 +83,13 @@ export default {
   nntpConnectionMaxMs: env.get('NNTP_CONNECTION_MAX_MINUTES', 0) * 60 * 1000,
   probe: {
     /**
-     * NNTP connections the prober reads articles with, besides the
+     * At most (its share, nntpShares): NNTP connections the prober reads articles with, besides the
      * coordinator's: the account has 50, the coordinator 40 + 1 plain, and a
      * couple stay free for downloads. ~7 MB/s each (~10 articles/s).
      */
     connections: env.get('PROBE_CONNECTIONS', 6),
+    /** Of them, always (its share's minimum; nntpShares). */
+    minConnections: env.get('PROBE_MIN_CONNECTIONS', 2),
     /** Candidates claimed at a time. */
     batch: 400,
     /** BODY commands in flight per connection (pipelined; XoverClient.bodies). */