fix: infer transcript MIME type from file extension instead of hardcoding text/plain

scripts/build-rss.ts

@@ -143,7 +143,7 @@ function generateRSSFeed(episodes: PodcastEpisode[], trailers: PodcastTrailer[],
       <itunes:duration>${episode.duration ? formatDurationForRSS(episode.duration) : '00:00'}</itunes:duration>
       <itunes:explicit>${episode.explicit ? 'yes' : 'no'}</itunes:explicit>
       ${episode.imageUrl ? `<itunes:image href="${escapeXml(episode.imageUrl)}" />` : ''}
-      ${transcriptUrl ? `<podcast:transcript url="${escapeXml(transcriptUrl)}" type="text/plain" />` : ''}
+      ${transcriptUrl ? `<podcast:transcript url="${escapeXml(transcriptUrl)}" type="${escapeXml(episode.transcriptType || 'text/plain')}" />` : ''}
       ${chaptersUrl ? `<podcast:chapters url="${escapeXml(chaptersUrl)}" type="application/json+chapters" />` : ''}
       ${episode.content ? `<content:encoded><![CDATA[${episode.content}]]></content:encoded>` : ''}
       ${episode.value && episode.value.enabled && episode.value.recipients && episode.value.recipients.length > 0 ?
@@ -219,8 +219,9 @@ function eventToPodcastEpisode(event: NostrEvent): PodcastEpisode {
     publishDate = new Date(event.created_at * 1000);
   }
 
-  // Extract transcript URL from tag
+  // Extract transcript URL and optional MIME type from tag
   const transcriptUrl = tags.get('transcript')?.[0];
+  const transcriptType = tags.get('transcript')?.[1] || 'text/plain';
 
   // Extract chapters URL from tag
   const chaptersUrl = tags.get('chapters')?.[0];
@@ -257,6 +258,7 @@ function eventToPodcastEpisode(event: NostrEvent): PodcastEpisode {
     videoType,
     imageUrl,
     transcriptUrl,
+    transcriptType,
     chaptersUrl,
     duration,
     episodeNumber,

src/hooks/usePublishEpisode.ts

@@ -8,6 +8,19 @@ import { PODCAST_KINDS, isPodcastCreator } from '@/lib/podcastConfig';
 import { usePodcastConfig } from '@/hooks/usePodcastConfig';
 import { addOP3Prefix } from '@/lib/op3Utils';
 
+/** Infer transcript MIME type from file extension (File.type is unreliable for .srt) */
+function inferTranscriptMime(filename: string, fileType: string): string {
+  const ext = filename.split('.').pop()?.toLowerCase();
+  const mimeMap: Record<string, string> = {
+    srt: 'application/x-subrip',
+    vtt: 'text/vtt',
+    json: 'application/json',
+    html: 'text/html',
+    txt: 'text/plain',
+  };
+  return mimeMap[ext ?? ''] || fileType || 'text/plain';
+}
+
 /**
  * Hook for publishing podcast episodes (creator only)
  */
@@ -94,10 +107,12 @@ export function usePublishEpisode() {
 
       // Upload transcript file if provided
       let transcriptUrl = episodeData.transcriptUrl;
+      let transcriptType = episodeData.transcriptType;
       if (episodeData.transcriptFile) {
         try {
           const transcriptTags = await uploadFile(episodeData.transcriptFile);
           transcriptUrl = transcriptTags[0][1];
+          transcriptType = inferTranscriptMime(episodeData.transcriptFile.name, episodeData.transcriptFile.type);
         } catch (error) {
           throw new Error(`Failed to upload transcript file: ${error instanceof Error ? error.message : 'Unknown error'}`);
         }
@@ -172,9 +187,11 @@ export function usePublishEpisode() {
         tags.push(['season', episodeData.seasonNumber.toString()]);
       }
 
-      // Add transcript URL if provided
+      // Add transcript URL and MIME type if provided
       if (transcriptUrl) {
-        tags.push(['transcript', transcriptUrl]);
+        transcriptType
+          ? tags.push(['transcript', transcriptUrl, transcriptType])
+          : tags.push(['transcript', transcriptUrl]);
       }
 
       // Add chapters URL if provided
@@ -309,10 +326,12 @@ export function useUpdateEpisode() {
 
       // Upload transcript file if provided
       let transcriptUrl = episodeData.transcriptUrl;
+      let transcriptType = episodeData.transcriptType;
       if (episodeData.transcriptFile) {
         try {
           const transcriptTags = await uploadFile(episodeData.transcriptFile);
           transcriptUrl = transcriptTags[0][1];
+          transcriptType = inferTranscriptMime(episodeData.transcriptFile.name, episodeData.transcriptFile.type);
         } catch (error) {
           throw new Error(`Failed to upload transcript file: ${error instanceof Error ? error.message : 'Unknown error'}`);
         }
@@ -415,9 +434,11 @@ export function useUpdateEpisode() {
         tags.push(['season', episodeData.seasonNumber.toString()]);
       }
 
-      // Add transcript URL if provided
+      // Add transcript URL and MIME type if provided
       if (transcriptUrl) {
-        tags.push(['transcript', transcriptUrl]);
+        transcriptType
+          ? tags.push(['transcript', transcriptUrl, transcriptType])
+          : tags.push(['transcript', transcriptUrl]);
       }
 
       // Add chapters URL if provided

src/types/podcast.ts

@@ -21,6 +21,7 @@ export interface PodcastEpisode {
   tags: string[];
   // Transcript and chapters as URL references
   transcriptUrl?: string;
+  transcriptType?: string; // MIME type (e.g. 'application/x-subrip', 'text/vtt')
   chaptersUrl?: string;
   guests?: PodcastGuest[];
   externalRefs?: ExternalReference[];
@@ -187,6 +188,7 @@ export interface RSSItem {
   image?: string;
   // Transcript and chapters as URL references
   transcriptUrl?: string;
+  transcriptType?: string; // MIME type (e.g. 'application/x-subrip', 'text/vtt')
   chaptersUrl?: string;
   funding?: Array<{
     url: string;