Judge: count a chunk's file hashes once, from a covering index

The incremental judge counted each changed release's files twice, each
index entry a heap fetch: 24-32 s a chunk. file_hashes by (hash16k,
size, release_id) replaces (hash16k); the other releases of a file are
judged only when the chunk brings it to 20.

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

database/migrations/1770000005000_file_hashes_hash_size_release.ts

@@ -0,0 +1,21 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+/**
+ * file_hashes by (hash16k, size, release_id), in place of (hash16k): how many releases have a file, from the index
+ * alone. The judge counts that for every file of each changed release (repeated); with the row fetched for size and
+ * release_id per entry, a file posted in 100k releases cost 100k heap reads every round (24–32 s a chunk; LOG.md
+ * 2026-10-19 (84)). The merger and pruner join on (hash16k, size) too.
+ */
+export default class extends BaseSchema {
+  static disableTransactions = true
+
+  async up() {
+    this.schema.raw(`CREATE INDEX CONCURRENTLY IF NOT EXISTS file_hashes_hash_size_release_idx ON file_hashes (hash16k, size, release_id)`)
+    this.schema.raw(`DROP INDEX CONCURRENTLY IF EXISTS file_hashes_hash_idx`)
+  }
+
+  async down() {
+    this.schema.raw(`CREATE INDEX CONCURRENTLY IF NOT EXISTS file_hashes_hash_idx ON file_hashes (hash16k)`)
+    this.schema.raw(`DROP INDEX CONCURRENTLY IF EXISTS file_hashes_hash_size_release_idx`)
+  }
+}