Seed leases respect the backfill's disk limits

No new range while the database's NVMe part or the hdd tablespace is over
BACKFILL_MAX_NVME_GB / BACKFILL_MAX_HDD_GB; nodes ask again a minute later.
seed:status says when leasing is paused. The NVMe part was at 47 GB of 50
with a plan for all of a.b.ath queued.

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

app/services/BackfillService.ts

@@ -90,7 +90,15 @@ class BackfillService {
   }
 
   /** True when both parts of the database are under their limits, else why not. */
-  private async room(maxDefaultGb: number, maxHddGb: number): Promise<true | string> {
+  /**
+   * Whether the database has room for more history: the default tablespace
+   * (NVMe) and tablespace `hdd` against BACKFILL_MAX_NVME_GB/_HDD_GB. Seed
+   * leases (CONCEPT.md D38) check the same limits.
+   */
+  async room(
+    maxDefaultGb = indexerConfig.backfill.maxDefaultGb,
+    maxHddGb = indexerConfig.backfill.maxHddGb
+  ): Promise<true | string> {
     const { rows } = await db.rawQuery(
       `SELECT spcname, pg_tablespace_size(oid) AS bytes FROM pg_tablespace WHERE spcname IN ('pg_default', 'hdd')`
     )

app/services/SeedOrchestrator.ts

@@ -2,6 +2,7 @@ import { createHash, randomBytes } from 'node:crypto'
 import db from '@adonisjs/lucid/services/db'
 import NntpService from '#services/NntpService'
 import SeedService from '#services/SeedService'
+import BackfillService from '#services/BackfillService'
 import { articleAtDate } from '#lib/nntp/date_search'
 import { normalizeSeedFile, type SeedBatch } from '#lib/seed/wire'
 
@@ -51,8 +52,13 @@ class SeedOrchestrator {
     return { id: Number(node.id), name: node.name }
   }
 
-  /** The next range for this node, oldest plan first; a quiet lease is taken over. */
+  /**
+   * The next range for this node, oldest plan first; a quiet lease is taken
+   * over. Nothing while the database is over the backfill's disk limits: the
+   * node asks again a minute later.
+   */
   async lease(nodeId: number): Promise<SeedLease | null> {
+    if ((await BackfillService.room()) !== true) return null
     // Ranges that broke node after node stop being handed out.
     await db.rawQuery(
       `UPDATE seed_ranges SET status = 'failed', error = coalesce(error, 'lease expired too often')
@@ -181,7 +187,8 @@ class SeedOrchestrator {
     const { rows: recent } = await db.rawQuery(
       `SELECT coalesce(sum(headers), 0)::bigint AS headers FROM seed_ranges WHERE done_at > now() - interval '1 hour'`
     )
-    return { ranges, nodes, headersDoneLastHour: Number(recent[0].headers) }
+    const room = await BackfillService.room()
+    return { ranges, nodes, headersDoneLastHour: Number(recent[0].headers), paused: room === true ? null : room }
   }
 }