feat(models): QueueTrack carries isrc/recording_mbid; Track models audio_info

QueueTrack gains two additive, serde-default identity keys (the ISRC and
the MusicBrainz recording id) that the listen log stamps; every
constructor in the workspace sets them (Qobuz-backed ones from
Track.isrc, local ones from the scanned tags, the rest None). They are
JOIN keys, not the row identity: numeric ids collide across sources, so
(source, native item id) stays the identity.

Track.audio_info (replaygain_track_gain / peak on DiscoverAudioInfo) is
modelled from the captured search envelopes; no reader yet and no
popularity field (0 in every sample).

cc

crates/qbz-app/src/playback_driver.rs

@@ -893,6 +893,8 @@ fn from_persisted(t: PersistedQueueTrack) -> QueueTrack {
         source_item_id_hint: t.source_item_id_hint,
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }
 

crates/qbz-app/src/session_persist.rs

@@ -247,6 +247,8 @@ fn from_persisted(t: PersistedQueueTrack) -> QueueTrack {
         // track's own album until the next container play re-stamps the queue.
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }
 

crates/qbz-core/src/core.rs

@@ -3614,6 +3614,7 @@ mod tests {
             title: String::new(),
             version: None,
             isrc: None,
+            audio_info: None,
             duration: 0,
             track_number: 0,
             media_number: None,

crates/qbz-mixtape/src/enqueue.rs

@@ -276,6 +276,8 @@ pub async fn resolve_qobuz_album(
                 source_item_id_hint: None,
                 context_kind: None,
                 context_id: None,
+                isrc: None,
+                recording_mbid: None,
             }
         })
         .collect();
@@ -370,6 +372,8 @@ pub fn track_to_queue_track_from_api(track: &ApiTrack) -> CoreQueueTrack {
         source_item_id_hint: None,
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }
 
@@ -416,6 +420,8 @@ mod tests {
                     source_item_id_hint: None, // stamped by resolve_collection_tracks
                     context_kind: None,
                     context_id: None,
+                    isrc: None,
+                    recording_mbid: None,
                 })
                 .collect())
         }
@@ -512,6 +518,8 @@ mod tests {
             source_item_id_hint: item.map(String::from),
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qbz-mixtape/src/shuffle.rs

@@ -365,6 +365,8 @@ mod tests {
             source_item_id_hint: None,
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qbz-models/src/playback.rs

@@ -69,6 +69,19 @@ pub struct QueueTrack {
     pub context_kind: Option<String>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub context_id: Option<String>,
+    /// Cross-source identity keys, when the source knows them: the ISRC (the
+    /// one key Qobuz always has) and the MusicBrainz recording id (Picard-
+    /// tagged local files, media servers that expose provider ids). Purely
+    /// additive — `None` everywhere that has not been taught them — and
+    /// stamped into the listen log, which is the only consumer today.
+    ///
+    /// NOT an identity on their own: numeric `id`s collide across sources,
+    /// so `(source, native item id)` stays the row identity and these are
+    /// the JOIN keys between sources.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub isrc: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub recording_mbid: Option<String>,
 }
 
 fn default_streamable() -> bool {

crates/qbz-models/src/source.rs

@@ -356,6 +356,8 @@ mod tests {
             source_item_id_hint: None,
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qbz-models/src/types.rs

@@ -477,6 +477,10 @@ pub struct Track {
     /// headers on the album view, mirroring the official Qobuz player (PR #536).
     pub work: Option<String>,
     pub isrc: Option<String>,
+    /// `audio_info` on the wire: replaygain gain/peak (always present in the
+    /// captured samples). Absent on older cached payloads → `None`.
+    #[serde(default)]
+    pub audio_info: Option<DiscoverAudioInfo>,
     #[serde(default)]
     pub duration: u32,
     #[serde(default)]
@@ -1426,12 +1430,20 @@ pub struct DiscoverAlbumDates {
     pub stream: Option<String>,
 }
 
-/// Audio info from discover album
+/// Audio info from discover album (and, since 2026-08-28, from tracks)
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct DiscoverAudioInfo {
     pub maximum_sampling_rate: Option<f64>,
     pub maximum_bit_depth: Option<u32>,
     pub maximum_channel_count: Option<u32>,
+    /// ReplayGain track gain (dB) and peak, as Qobuz ships them on every
+    /// track in search/album envelopes
+    /// (`qbz-nix-docs/qobuz-api/search-results-response.json`, 15 samples).
+    /// Modelled only — no reader yet; the loudness analyser stays as is.
+    #[serde(default)]
+    pub replaygain_track_gain: Option<f64>,
+    #[serde(default)]
+    pub replaygain_track_peak: Option<f64>,
 }
 
 // ============ Artist Page Types (/artist/page) ============

crates/qbz-player/src/queue.rs

@@ -1772,6 +1772,8 @@ mod tests {
             source_item_id_hint: None,
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qbz-playlist-import/src/match_qobuz.rs

@@ -397,6 +397,7 @@ mod tests {
             version: None,
             work: None,
             isrc: None,
+            audio_info: None,
             duration: 0,
             track_number: 0,
             media_number: None,

crates/qbz-qt/src/artist_qt.rs

@@ -938,6 +938,8 @@ fn track_row_to_queue(row: &TrackRow) -> QueueTrack {
         source_item_id_hint: None,
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }
 

crates/qbz-qt/src/bulk_tracks_qt.rs

@@ -88,6 +88,8 @@ fn queue_track(track: &Track) -> qbz_models::QueueTrack {
         source_item_id_hint: album_key,
         context_kind: None,
         context_id: None,
+        isrc: track.isrc.clone(),
+        recording_mbid: None,
     }
 }
 

crates/qbz-qt/src/foryou_qt.rs

@@ -1157,6 +1157,8 @@ pub(crate) fn to_queue_track(track: &Track) -> QueueTrack {
         source_item_id_hint: album_key,
         context_kind: None,
         context_id: None,
+        isrc: track.isrc.clone(),
+        recording_mbid: None,
     }
 }
 

crates/qbz-qt/src/home_qt.rs

@@ -2084,6 +2084,8 @@ mod tests {
             maximum_sampling_rate: rate,
             maximum_bit_depth: depth,
             maximum_channel_count: None,
+            replaygain_track_gain: None,
+            replaygain_track_peak: None,
         }
     }
 

crates/qbz-qt/src/label_qt.rs

@@ -1464,6 +1464,8 @@ fn track_row_to_queue(row: &TrackRow) -> QueueTrack {
         source_item_id_hint: None,
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }
 

crates/qbz-qt/src/library_qt.rs

@@ -2040,6 +2040,8 @@ pub(crate) fn feed_track_to_queue(item: &FeedItem) -> Option<QueueTrack> {
         source_item_id_hint: None,
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     })
 }
 

crates/qbz-qt/src/local_playback.rs

@@ -329,6 +329,9 @@ pub fn local_queue_track(t: &LocalTrack) -> QueueTrack {
         // nothing and falls back per track to the same key.
         context_kind: None,
         context_id: None,
+        // Identity straight from the scanned tags (None on untagged files).
+        isrc: t.isrc.clone(),
+        recording_mbid: t.musicbrainz_recording_id.clone(),
     }
 }
 

crates/qbz-qt/src/local_playlist_qt.rs

@@ -734,6 +734,8 @@ pub(crate) fn row_to_display(item: &RowItem) -> (PlaylistTrackRow, Option<QueueT
                 source_item_id_hint: None,
                 context_kind: None,
                 context_id: None,
+                isrc: None,
+                recording_mbid: None,
             };
             (row, Some(queue))
         }

crates/qbz-qt/src/mini_qt.rs

@@ -293,6 +293,8 @@ mod tests {
             source_item_id_hint: None,
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qbz-qt/src/playlist_qt.rs

@@ -875,6 +875,8 @@ fn row_to_queue(row: &PlaylistTrackRow) -> QueueTrack {
         // the playlist id is in scope instead (`open_context` / `queue_for`).
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }
 

crates/qbz-qt/src/qconnect_qt.rs

@@ -3318,6 +3318,8 @@ mod tests {
             source_item_id_hint: None,
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qbz-qt/src/queue_qt.rs

@@ -1538,6 +1538,8 @@ mod tests {
             source_item_id_hint: None,
             context_kind: None,
             context_id: None,
+            isrc: None,
+            recording_mbid: None,
         }
     }
 

crates/qconnect-app/src/renderer.rs

@@ -103,6 +103,8 @@ pub fn model_track_to_core_queue_track(track: &Track) -> QueueTrack {
         source_item_id_hint: album_id,
         context_kind: None,
         context_id: None,
+        isrc: None,
+        recording_mbid: None,
     }
 }