From 04a29b684d6f5b723eecdc4f6f9bfa27e6b17d41 Mon Sep 17 00:00:00 2001
From: Honey <me_honeyy@proton.me>
Date: Sun, 26 Jul 2026 21:19:09 +0200
Subject: [PATCH] fix(backend): match official audio by yt-dlp artist metadata,
 not just channel name
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The strict cascade steps required the YouTube channel name to contain the artist, so
official uploads on label channels (BANGTANTV, HYBE LABELS, …) were rejected and the
no-channel fallback grabbed a fan reupload instead (observed: BTS "Pied Piper").

Add yt-dlp's music `artist` field as an OR alternative to the channel check in the
strict steps (two --match-filter args = OR). A metadata dump of "BTS Pied Piper"
confirmed only the official upload has artist=BTS (fan/live/lyric reuploads: NA), and
it's the #1 result — so it now passes strict step 2. channel_is_verified was rejected
as a signal: lyric videos and fan MVs also run on verified channels.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 CLAUDE.md            |  7 +++++++
 backend/lib/ytdlp.js | 17 +++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/CLAUDE.md b/CLAUDE.md
index 9d5b1e5..39c3c89 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -53,6 +53,13 @@ Backend runs in Docker (see `docker-compose.yml`); on the deploy host it lives a
 - **Search cascade** (`ytdlp.js`): YTM search first (`web_music` player client, Songs filter
   param), then regular YouTube; each candidate filtered by duration (±10%, min 10s),
   title keyword, artist channel, and variant exclusions (remix/cover/sped/…).
+- **Official audio via `artist` metadata (not just channel).** The strict steps accept a candidate
+  if the channel name matches the artist **OR** yt-dlp's music `artist` field does. YouTube "Art
+  Tracks" (label-provided official audio) carry `artist=<Artist>` even when the channel is
+  `BANGTANTV`/`HYBE LABELS`/… (no artist name). Confirmed on "BTS Pied Piper": only the official
+  upload had `artist=BTS`; every fan/live/lyric reupload had `artist=NA`. `channel_is_verified` was
+  rejected as a signal — lyric videos and fan MVs also run on verified channels. Implemented as two
+  `--match-filter` args (yt-dlp OR's them) in `mf()`.
 - **"Mittelweg" rule** (with AND without duration): when nothing matches in the filtered steps,
   relax only the duration constraint while **still requiring the artist channel**. If nothing
   matches, download **nothing** and fail cleanly with "Nicht eindeutig gefunden — bitte
diff --git a/backend/lib/ytdlp.js b/backend/lib/ytdlp.js
index b49277f..efbb36e 100644
--- a/backend/lib/ytdlp.js
+++ b/backend/lib/ytdlp.js
@@ -122,6 +122,12 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
   const artistFirstWord = (rawArtist || mainArtist).split(/[\s,/]+/)[0];
   const artistChannelPart = (artistFirstWord.length >= 3 && !JP_RE.test(artistFirstWord))
     ? ` & channel ~= (?i)${escRe(artistFirstWord)}` : '';
+  // yt-dlp fills `artist` (music metadata) on YouTube "Art Tracks" — the label-provided official
+  // audio — even when the channel doesn't contain the artist name (BANGTANTV/HYBE/…). Verified with
+  // "BTS Pied Piper": ONLY the official upload had artist=BTS; every fan/live/lyric reupload had
+  // none. Used as an OR alternative to the channel check so those official uploads still pass strict.
+  const artistMetaPart = (artistFirstWord.length >= 3 && !JP_RE.test(artistFirstWord))
+    ? ` & artist ~= (?i)${escRe(artistFirstWord)}` : '';
 
   // Use a space (not " - ") between artist and title: this matches how users type
   // in the YTM search box and ranks the exact official track first. A dash skews
@@ -240,8 +246,15 @@ async function downloadTrack({ jobId, artist, rawArtist, albumArtist, title, alb
     } else {
       durPart = '';
     }
-    return ['--match-filter',
-      `${durPart}!is_live${titleKwPart}${strict ? artistChannelPart : ''}${variant ? variantPart : ''}`];
+    const base = `${durPart}!is_live${titleKwPart}${variant ? variantPart : ''}`;
+    // Non-strict, or no artist constraint (short / Japanese name): single filter.
+    if (!strict || !artistChannelPart) return ['--match-filter', base];
+    // Strict: pass if the channel name matches the artist OR yt-dlp's music `artist` metadata does
+    // (catches official label-channel uploads like BANGTANTV). Two --match-filter args = OR in yt-dlp.
+    return [
+      '--match-filter', `${base}${artistChannelPart}`,
+      '--match-filter', `${base}${artistMetaPart}`,
+    ];
   };
 
   const PI_FILTERED    = ['--playlist-items', '1-5',  '--max-downloads', '1'];