diff --git a/src/plugin.ts b/src/plugin.ts
index b9e73d5..b240050 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -451,10 +451,19 @@ async function registerSubtitle(
     opts: SubtitleOpts,
 ): Promise<void> {
     // 1. Companion subtitle-file record (fileType=subtitle, lang, video backref).
+    //
+    // `source/gateway:opensubtitles` is the SAME label meta-feeder-opensubtitles
+    // stamps on the records it mints (METADATA_KEYS.md §5), deliberately: a
+    // subtitle's provenance must not depend on which of the two paths fetched
+    // it, and meta-watch already reads that one prefix to name the provider.
+    // It belongs on the subtitle's own record rather than on the video's,
+    // because a subtitle fetched over the swarm by CID arrives without the
+    // video record — anything stored there does not travel with the file.
     const companion: Record<string, string> = {
         fileType: 'subtitle',
         extension: opts.extension,
         subtitleLanguage: lang3,
+        'source/gateway:opensubtitles': 'true',
         [`videos/${videoCid}`]: 'true',
     };
     if (opts.fileName) companion.fileName = opts.fileName;