diff --git a/pipeline/lib/tag-guard.sh b/pipeline/lib/tag-guard.sh
index d8e2568..361938a 100755
--- a/pipeline/lib/tag-guard.sh
+++ b/pipeline/lib/tag-guard.sh
@@ -19,6 +19,42 @@
 # which is the lesser of two evils vs. corrupting real band names.
 _PRIMARY_ARTIST_SEP_PATTERN=' / | feat\. | feat | ft\. | ft |; '
 
+# Read one ID3 text frame (e.g. TPE1, TIT2, TPE2) via mutagen instead of the
+# `id3v2` CLI. id3v2 is id3lib-3.8.3 (last released 2013) and cannot parse
+# ID3v2.4 tags at all -- it reports "No ID3 tag" on a file that has complete,
+# valid tags, just written in the modern version most taggers (Mp3tag,
+# yt-dlp, foobar2000) default to. That false negative used to send fully-
+# tagged mp3s to quarantine. Usage: _mp3_tag <file> <frame>
+_mp3_tag() {
+  python3 - "$1" "$2" 2>/dev/null <<'PY'
+import sys
+from mutagen.id3 import ID3
+try:
+    tags = ID3(sys.argv[1])
+    frame = tags.get(sys.argv[2])
+    print(str(frame) if frame else "")
+except Exception:
+    print("")
+PY
+}
+
+# Set one ID3 text frame via mutagen, preserving every other frame on the
+# file. The `id3v2` CLI cannot be used for this: writing even a single frame
+# with it to a file that already has an ID3v2.4 tag silently drops every
+# other frame (title, album, genre, date, artwork -- all of it), because
+# id3lib doesn't understand v2.4 and rewrites the whole tag as v2.3 with only
+# the frame(s) it was told to set. Usage: _mp3_set_tag <file> <frame> <value>
+_mp3_set_tag() {
+  python3 - "$1" "$2" "$3" <<'PY'
+import sys
+from mutagen.id3 import ID3, Frames
+tags = ID3(sys.argv[1])
+frame_cls = Frames[sys.argv[2]]
+tags.setall(sys.argv[2], [frame_cls(encoding=3, text=[sys.argv[3]])])
+tags.save(sys.argv[1])
+PY
+}
+
 # For each audio file under $scan_dir that has no ALBUMARTIST tag, set
 # ALBUMARTIST to the primary artist (everything before the first separator
 # in the ARTIST tag). Prevents Navidrome from coining ghost album-artists
@@ -45,12 +81,12 @@ set_albumartist_fallback() {
         ;;
       mp3|MP3)
         local cur_aa artist primary
-        cur_aa=$(id3v2 -l "$file" 2>/dev/null | sed -n 's/^TPE2[^:]*: //p' | head -1)
+        cur_aa=$(_mp3_tag "$file" TPE2)
         [[ -n "$cur_aa" ]] && continue
-        artist=$(id3v2 -l "$file" 2>/dev/null | sed -n 's/^TPE1[^:]*: //p' | head -1)
+        artist=$(_mp3_tag "$file" TPE1)
         [[ -z "$artist" ]] && continue
         primary=$(echo "$artist" | sed -E "s#(${_PRIMARY_ARTIST_SEP_PATTERN}).*##")
-        id3v2 --TPE2 "$primary" "$file" 2>>"$logfile"
+        _mp3_set_tag "$file" TPE2 "$primary" 2>>"$logfile"
         count=$((count + 1))
         ;;
     esac
@@ -76,8 +112,8 @@ quarantine_untagged() {
 
   _has_mp3_tags() {
     local artist title
-    artist=$(id3v2 -l "$1" 2>/dev/null | sed -n 's/^TPE1[^:]*: //p' | head -1)
-    title=$(id3v2  -l "$1" 2>/dev/null | sed -n 's/^TIT2[^:]*: //p' | head -1)
+    artist=$(_mp3_tag "$1" TPE1)
+    title=$(_mp3_tag "$1" TIT2)
     [[ -n "$artist" && -n "$title" ]]
   }