Complete archive listings by walking RAR headers, at low priority

Inspection lists only the entries whose headers are in the first segment
of a first volume. A walk hops from header to header, fetching one segment
per entry and volume, in its own queue (one job per collection worker) on
NNTP connections inspection isn't waiting for. content:walk-archives queues
releases inspected earlier (CONCEPT D40).

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

lib/content/archive_names.ts

@@ -23,3 +23,18 @@ export function isLaterVolume(name: string): boolean {
   if (part) return Number(part[1]) > 1
   return /\.r\d{2,3}$/i.test(name) || /\.vol\d+[+-]\d+\.par2$/i.test(name)
 }
+
+/**
+ * The set and 1-based number of a RAR volume: `x.part03.rar` is volume 3 of
+ * `x`, and in the old naming `x.rar` is 1, `x.r00` 2, `x.r01` 3. Null for
+ * other names.
+ */
+export function rarVolume(name: string): { base: string; number: number } | null {
+  const part = /^(.*)\.part(\d+)\.rar$/i.exec(name)
+  if (part) return { base: part[1].toLowerCase(), number: Number(part[2]) }
+  const old = /^(.*)\.r(\d{2,3})$/i.exec(name)
+  if (old) return { base: old[1].toLowerCase(), number: Number(old[2]) + 2 }
+  const first = /^(.*)\.rar$/i.exec(name)
+  if (first) return { base: first[1].toLowerCase(), number: 1 }
+  return null
+}

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, isLaterVolume } from './archive_names.js'
+export { isArchiveStart, isLaterVolume, rarVolume } 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'