Prober: claim only candidates of settled releases, without the join

The settler marks a settled release's candidates ready (and unreadable when
it had no readable name). Claims took the candidates by joining releases
from random points of the queue; in its newer half nothing had settled, so
a slice scanned to the end (0.3 s each, 20 slices and 5 tiers a claim) and
the prober stood still: 2.4M waiting, 0 probed a minute. Now an index over
the claimable rows only, the slices drawn within them.

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

database/migrations/1770000002500_probe_candidates_ready.ts

@@ -0,0 +1,30 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+/**
+ * Candidates the prober may claim (Prober.claim): `ready` once their release
+ * settled (the settler sets it), `unreadable` when that release had no
+ * readable name then. The claims joined releases for both and started at
+ * random points of the queue; in its newer half nothing had settled, so a
+ * slice scanned to the end (0.3 s a slice, 20 slices, 5 tiers: the prober
+ * stood still for minutes per claim; LOG.md 2026-10-12 (20)). With an index
+ * over the claimable rows only.
+ */
+export default class extends BaseSchema {
+  static disableTransactions = true
+
+  async up() {
+    this.schema.raw(`ALTER TABLE probe_candidates ADD COLUMN IF NOT EXISTS ready boolean NOT NULL DEFAULT false`)
+    this.schema.raw(`ALTER TABLE probe_candidates ADD COLUMN IF NOT EXISTS unreadable boolean NOT NULL DEFAULT false`)
+    this.schema.raw(
+      `UPDATE probe_candidates pc SET ready = true, unreadable = NOT r.readable FROM releases r
+       WHERE r.id = pc.release_id AND r.settled_at IS NOT NULL AND NOT pc.ready`
+    )
+    this.schema.raw(`CREATE INDEX CONCURRENTLY IF NOT EXISTS probe_candidates_ready_idx ON probe_candidates (kind, unreadable, id) WHERE status = 'waiting' AND ready`)
+    this.schema.raw(`DROP INDEX CONCURRENTLY IF EXISTS probe_candidates_kind_waiting_idx`)
+  }
+
+  async down() {
+    this.schema.raw(`DROP INDEX CONCURRENTLY IF EXISTS probe_candidates_ready_idx`)
+    this.schema.raw(`ALTER TABLE probe_candidates DROP COLUMN IF EXISTS ready, DROP COLUMN IF EXISTS unreadable`)
+  }
+}

database/schema.ts

@@ -169,7 +169,7 @@ export class ProbeCacheSchema extends BaseModel {
 }
 
 export class ProbeCandidateSchema extends BaseModel {
-  static $columns = ['createdAt', 'file', 'id', 'kind', 'messageId', 'releaseId', 'status'] as const
+  static $columns = ['createdAt', 'file', 'id', 'kind', 'messageId', 'ready', 'releaseId', 'status', 'unreadable'] as const
   $columns = ProbeCandidateSchema.$columns
   @column.dateTime({ autoCreate: true })
   declare createdAt: DateTime
@@ -182,9 +182,13 @@ export class ProbeCandidateSchema extends BaseModel {
   @column()
   declare messageId: string
   @column()
+  declare ready: boolean
+  @column()
   declare releaseId: bigint | number
   @column()
   declare status: string
+  @column()
+  declare unreadable: boolean
 }
 
 export class RangeSchema extends BaseModel {