Inspect fewer files: skip later volumes under random stems

Of 5,000 waiting inspection jobs, 3,212 were queued only because their
stem looked random, and 2,044 of those were later RAR volumes
(xyz.part47.rar, .r00) or par2 recovery volumes (.vol03+04.par2). Their
first segment adds nothing: the set is listed from its first volume and
named from its index .par2, as for readable names already. Each one cost a
~700 KB download; inspection pulled ~85 MB/s and fell behind the backfill.

- isCandidate() rejects later volumes (isLaterVolume) before the random-
  name rule.
- worker:file only queues files that are candidates, so the ~30% that
  inspection skips anyway no longer take queue slots.

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

app/services/ContentService.ts

@@ -8,6 +8,7 @@ import { decodeSegment, YencCrcError, YencError, YencFile } from '#lib/yenc/inde
 import NzbImportService, { type NzbImportResult } from '#services/NzbImportService'
 import {
   isArchiveStart,
+  isLaterVolume,
   NICOVIDEO_FILE,
   NICOVIDEO_RELEASE,
   nicovideoInfo,
@@ -68,6 +69,8 @@ export interface ContentResult {
 class ContentService {
   /** Random or missing names, and named first RAR volumes (for contents and password flag). */
   isCandidate(name: string) {
+    // Even under a random stem: the first volume and the index .par2 are inspected instead.
+    if (isLaterVolume(name)) return false
     if (!looksLikeFilename(name) || looksRandom(fileStem(name))) return true
     if (isArchiveStart(name)) return true
     if (/\.nzb$/i.test(name)) return true

commands/workers/File.ts

@@ -8,6 +8,7 @@ import SfvService from '#services/SfvService'
 import queueConfig from '#config/queue'
 import Shutdown from '#services/Shutdown'
 import QueueService from '#services/QueueService'
+import ContentService from '#services/ContentService'
 
 export default class FileWorker extends BaseCommand {
   public static commandName = 'worker:file'
@@ -94,7 +95,10 @@ export default class FileWorker extends BaseCommand {
         date: binary.posted_at ? new Date(binary.posted_at).getTime() : null,
         release_id: binary.release_id,
       })
-      await collectionQueue.add('process-collection', { fileId }, { jobId: `file-${fileId}` })
+      // Files inspection would skip anyway (later volumes, readable media names) don't take a queue slot.
+      if (ContentService.isCandidate(binary.name)) {
+        await collectionQueue.add('process-collection', { fileId }, { jobId: `file-${fileId}` })
+      }
     }, {
       connection: queueConfig.connection,
       // One job at a time could not keep up with the backfill (130k waiting); jobs are per binary and

lib/content/archive_names.ts

@@ -11,3 +11,15 @@ export function isArchiveStart(name: string): boolean {
   if (volume === 0 || volume === 1) return true
   return /\.part0*1\.rar$/i.test(name) || (/\.rar$/i.test(name) && !/\.part\d+\.rar$/i.test(name))
 }
+
+/**
+ * A later RAR volume (.part02.rar, .r00) or a par2 recovery volume
+ * (.vol03+04.par2): the volume number is readable even under a random stem.
+ * The set is listed from its first volume and named from its index .par2,
+ * so the first segment of these says nothing new (LOG.md 2026-10-04).
+ */
+export function isLaterVolume(name: string): boolean {
+  const part = /\.part(\d+)\.rar$/i.exec(name)
+  if (part) return Number(part[1]) > 1
+  return /\.r\d{2,3}$/i.test(name) || /\.vol\d+[+-]\d+\.par2$/i.test(name)
+}

lib/content/index.ts

@@ -2,6 +2,6 @@
  * Content recognition by magic bytes, independent of AdonisJS.
  */
 export { sniffContentType, type ContentType } from './sniff.js'
-export { isArchiveStart } from './archive_names.js'
+export { isArchiveStart, isLaterVolume } from './archive_names.js'
 export { parseSfv, sfvReleaseName, type SfvEntry } from './sfv.js'
 export { NICOVIDEO_FILE, NICOVIDEO_RELEASE, nicovideoInfo, nicovideoReleaseName, zstdPrefix, tarEntries, type NicovideoInfo } from './nicovideo.js'

tests/unit/content.spec.ts

@@ -1,6 +1,6 @@
 import { test } from '@japa/runner'
 import yencode from 'yencode'
-import { sniffContentType } from '#lib/content/index'
+import { isLaterVolume, sniffContentType } from '#lib/content/index'
 import { crc32Hex, decodeSegment, YencError } from '#lib/yenc/index'
 
 test.group('content / sniffContentType', () => {
@@ -52,3 +52,14 @@ test.group('yenc / lenientSize', () => {
     assert.isTrue(decodeSegment(body, { lenientSize: true }).data.equals(data))
   })
 })
+
+test.group('content / isLaterVolume', () => {
+  test('recognises later RAR volumes and par2 recovery volumes, also under a random stem', ({ assert }) => {
+    for (const name of ['P8vttYaPec1mL4nDZHPZo7Nd6iEWj8lP.part47.rar', 'Show.S01E01.part002.rar', 'abc.r00', 'abc.r123', 'x7Kq9.vol03+04.par2', 'Show.vol127-128.par2']) {
+      assert.isTrue(isLaterVolume(name), name)
+    }
+    for (const name of ['P8vttYaPec1mL4nDZHPZo7Nd6iEWj8lP.part01.rar', 'abc.part1.rar', 'abc.rar', 'x7Kq9.par2', '6e13186238ab54ca498e46d2d77da099', 'abc.7z.002', 'abc.mkv']) {
+      assert.isFalse(isLaterVolume(name), name)
+    }
+  })
+})