fix: compare ZIM catalog versions numerically

admin/app/utils/zim_download_resolution.ts

@@ -7,13 +7,31 @@ export type ResolvedZimDownload = {
   sizeBytes: number | undefined
 }
 
+function compareZimVersions(left: string, right: string): number {
+  const parse = (value: string): [number, number] | null => {
+    const match = /^(\d{4})-(\d{1,2})$/.exec(value)
+    if (!match) return null
+
+    const month = Number.parseInt(match[2], 10)
+    if (month < 1 || month > 12) return null
+
+    return [Number.parseInt(match[1], 10), month]
+  }
+
+  const leftParts = parse(left)
+  const rightParts = parse(right)
+  if (!leftParts || !rightParts) return left.localeCompare(right)
+
+  return leftParts[0] - rightParts[0] || leftParts[1] - rightParts[1]
+}
+
 export function resolveZimDownload(
   resource: SpecResource,
   latest: CatalogResult | null
 ): ResolvedZimDownload {
   const manifestSizeBytes = resource.size_mb > 0 ? resource.size_mb * 1024 * 1024 : undefined
 
-  if (!latest || latest.version < resource.version) {
+  if (!latest || compareZimVersions(latest.version, resource.version) < 0) {
     return {
       url: resource.url,
       version: resource.version,

admin/tests/unit/zim_download_resolution.spec.ts

@@ -54,3 +54,22 @@ test('older catalog result does not replace newer manifest metadata', () => {
   assert.equal(resolved.url, manifestResource.url)
   assert.equal(resolved.version, manifestResource.version)
 })
+
+test('non-padded catalog months are compared numerically', () => {
+  const resource = {
+    ...manifestResource,
+    version: '2026-2',
+    url: 'https://download.kiwix.org/zim/wikipedia/wikipedia_en_all_mini_2026-2.zim',
+  }
+  const resolved = resolveZimDownload(resource, {
+    version: '2026-10',
+    download_url: 'https://download.kiwix.org/zim/wikipedia/wikipedia_en_all_mini_2026-10.zim',
+    size_bytes: 13_000,
+  })
+
+  assert.equal(
+    resolved.url,
+    'https://download.kiwix.org/zim/wikipedia/wikipedia_en_all_mini_2026-10.zim'
+  )
+  assert.equal(resolved.version, '2026-10')
+})