Seed leases alternate between priorities; article relay can be off

Half the live leases go to higher-priority ranges, the rest to the others,
so a slow recent gap runs beside older history. With no article
connections the article relay answers 503 instead of waiting forever.

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

app/controllers/seed_controller.ts

@@ -1,7 +1,7 @@
 import type { HttpContext } from '@adonisjs/core/http'
 import SeedOrchestrator, { LeaseLost } from '#services/SeedOrchestrator'
 import SeedFetchPool from '#services/SeedFetchPool'
-import RemoteContentService, { JobLost } from '#services/RemoteContentService'
+import RemoteContentService, { ArticleRelayOff, JobLost } from '#services/RemoteContentService'
 import type { SeedBatch } from '#lib/seed/wire'
 
 /**
@@ -123,6 +123,7 @@ export default class SeedController {
       response.header('content-type', 'application/octet-stream')
       return response.send(body)
     } catch (error: any) {
+      if (error instanceof ArticleRelayOff) return response.serviceUnavailable({ error: error.message })
       return response.badGateway({ error: `NNTP: ${error.message}` })
     }
   }

app/services/RemoteContentService.ts

@@ -2,6 +2,7 @@ import { randomUUID } from 'node:crypto'
 import { Job, Worker } from 'bullmq'
 import logger from '@adonisjs/core/services/logger'
 import queueConfig from '#config/queue'
+import nntpConfig from '#config/nntp'
 import QueueService from '#services/QueueService'
 import NntpService from '#services/NntpService'
 import ContentService, { describeContent } from '#services/ContentService'
@@ -24,6 +25,7 @@ export interface RemoteJob {
 }
 
 export class JobLost extends Error {}
+export class ArticleRelayOff extends Error {}
 
 /**
  * Content inspection and archive walks on seeding nodes (CONCEPT.md D41).
@@ -99,6 +101,8 @@ class RemoteContentService {
 
   /** One article body for a relay node, on this process's NNTP pool. Null when the server doesn't have it. */
   async article(messageId: string): Promise<Buffer | null> {
+    // NNTP_POOL_SIZE 0 (SEED_ARTICLE_CONNECTIONS=0): no connections for this; acquire() would wait forever.
+    if (nntpConfig.poolSize <= 0) throw new ArticleRelayOff('Article relay is off (SEED_ARTICLE_CONNECTIONS=0)')
     const conn = await NntpService.acquire()
     let failed = false
     try {

app/services/SeedOrchestrator.ts

@@ -73,12 +73,21 @@ class SeedOrchestrator {
        WHERE status = 'leased' AND heartbeat_at < now() - make_interval(secs => ?) AND attempts >= ?`,
       [LEASE_TTL_SECONDS, MAX_ATTEMPTS]
     )
+    // Priorities take turns: while ranges of a higher priority are leased for less than half of
+    // the work in progress they go first, otherwise the rest does (a 2026 gap fetches ~5x slower
+    // than older history; LOG.md 2026-10-06 (10)).
+    const { rows: mix } = await db.rawQuery(
+      `SELECT count(*) FILTER (WHERE priority > 0) AS high, count(*) AS all FROM seed_ranges
+       WHERE status = 'leased' AND heartbeat_at >= now() - make_interval(secs => ?)`,
+      [LEASE_TTL_SECONDS]
+    )
+    const order = Number(mix[0].high) * 2 < Number(mix[0].all) + 1 ? 'priority DESC, id' : 'priority ASC, id'
     const { rows } = await db.rawQuery(
       `UPDATE seed_ranges SET status = 'leased', node_id = ?, leased_at = now(), heartbeat_at = now(), attempts = attempts + 1
        WHERE id = (
          SELECT id FROM seed_ranges
          WHERE status = 'queued' OR (status = 'leased' AND heartbeat_at < now() - make_interval(secs => ?))
-         ORDER BY priority DESC, id LIMIT 1 FOR UPDATE SKIP LOCKED)
+         ORDER BY ${order} LIMIT 1 FOR UPDATE SKIP LOCKED)
        RETURNING id, group_name, next_id, end_id`,
       [nodeId, LEASE_TTL_SECONDS]
     )

tests/functional/seed_api.spec.ts

@@ -144,6 +144,20 @@ test.group('Seed API', (group) => {
     assert.include(leased.body().range, { start: 101, end: 200 })
   })
 
+  test('priorities take turns: half the leases go to the higher priority', async ({ client, assert }) => {
+    const token = await SeedOrchestrator.issueToken('turns-node')
+    const auth = { authorization: `Bearer ${token}` }
+    await db.table('seed_ranges').insert([
+      { group_name: 'alt.binaries.test', start_id: 1, end_id: 100, next_id: 1 },
+      { group_name: 'alt.binaries.test', start_id: 101, end_id: 200, next_id: 101 },
+      { group_name: 'alt.binaries.test', start_id: 1001, end_id: 1100, next_id: 1001, priority: 1 },
+      { group_name: 'alt.binaries.test', start_id: 1101, end_id: 1200, next_id: 1101, priority: 1 },
+    ])
+    const starts: number[] = []
+    for (let i = 0; i < 4; i++) starts.push((await client.post('/api/v1/seed/lease').headers(auth)).body().range.start)
+    assert.deepEqual(starts, [1001, 1, 1101, 101])
+  })
+
   test('a node inspects a file: lease, probe result, applied here (D41)', async ({ client, assert }) => {
     await QueueService.collectionQueue.drain()
     await QueueService.archiveWalkQueue.drain()