par2 file lists dropped once their holders are final; late candidates claimable

Most par2 sets describe readable uploads whose files are never hashed, so they
were never complete and kept forever (19 GB). Candidates added to a release
after it settled were never marked ready (93,642 since 2026-10-13); the batch
store and merge mark them now, migration 5100 repairs the waiting ones
(LOG.md 2026-10-20 (87)).

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

database/migrations/1770000005100_late_candidates_ready.ts

@@ -0,0 +1,17 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+/**
+ * Probe candidates added to a release after it settled (a later range of its upload, a merge into it) stayed not
+ * ready: the settler marks a release's candidates only when it settles it (LOG.md 2026-10-20 (87)). 93,642 waited
+ * since 2026-10-13 (17k lone, 31k par2, 45k archive). The batch store and the merge mark them now; these are made
+ * claimable once.
+ */
+export default class extends BaseSchema {
+  async up() {
+    this.schema.raw(`
+      UPDATE probe_candidates pc SET ready = true, unreadable = NOT r.readable FROM releases r
+      WHERE pc.status = 'waiting' AND NOT pc.ready AND r.id = pc.release_id AND r.settled_at IS NOT NULL`)
+  }
+
+  async down() {}
+}