refactor(frontend): retire Slint application

cx

crates/qbz-offline-cache/src/purchases_service.rs

@@ -1012,84 +1012,6 @@ pub async fn download_purchase_track(
     Ok(file_path)
 }
 
-/// Download-ONLY variant of the single-track primitive: identical CDN fetch +
-/// `.part`→rename pipeline as `download_purchase_track`, but it does **NOT**
-/// write the `downloaded_purchases` registry. Returns the final on-disk path.
-///
-/// **This function's original rationale was WRONG, and it is kept only because
-/// `qbz-slint` calls it.** New code must not use it. Verified against the
-/// reference on 2026-08-16:
-///
-/// The comment here used to claim that Svelte's `executeAlbumDownload` marks a
-/// track `'complete'` first and then writes the registry as a best-effort step
-/// that swallows failure, and therefore that an album-path registry failure
-/// leaves the track `'complete'` but unregistered. That misreads the reference.
-/// `executeAlbumDownload` awaits `downloadTrack`, which invokes
-/// `v2_purchases_download_track` — and THAT command writes the registry itself
-/// and propagates the error with `?` (`legacy_compat.rs:3019-3021`). So a
-/// registry failure throws out of `downloadTrack`, is caught by the loop's
-/// `catch`, and the track is marked **`'failed'`**, exactly as on the
-/// single-track path. The `markTrackDownloaded(...).catch(() => {})` that follows
-/// (`purchaseDownloadStore.ts:147`) is a SECOND, backfill-only write whose sole
-/// effect is filling the `album_id` column; its swallowed failure costs that
-/// column and nothing else.
-///
-/// Consequence: this "write the file, register separately" split has no basis in
-/// the reference, and the Slint controller's use of it is the one silent
-/// divergence in the purchases port — it leaves files on disk with no registry
-/// row while reporting success. The Qt controller uses
-/// `download_purchase_track` with `Some(album_id)` instead, which registers
-/// inside the same call and propagates.
-///
-/// Addendum B.2 (extension from RESPONSE, registry/qualityDir from REQUESTED),
-/// B.3 (silent overwrite), and B.5 (restrictions ignored) hold identically to
-/// `download_purchase_track`.
-pub async fn download_purchase_track_file_only(
-    client: &QobuzClient,
-    track_id: u64,
-    format_id: u32,
-    destination: &str,
-    quality_dir: &str,
-) -> Result<String, String> {
-    // UNSIGNED on the purchase path (contract §11-6): the vendor's own desktop
-    // client sends `/track/get` without a signature, and so did the reference.
-    // The entitlement proof is the signature on `getFileUrl` below, which is
-    // untouched.
-    let track = client
-        .get_track_for_purchase(track_id)
-        .await
-        .map_err(|e| format!("Failed to fetch track {}: {}", track_id, e))?;
-    let stream = client
-        .get_track_file_url_by_format(track_id, format_id)
-        .await
-        .map_err(|e| format!("Failed to get download URL for track {}: {}", track_id, e))?;
-
-    let data = QobuzClient::download_audio(&stream.url).await?;
-
-    let artist_name = track
-        .performer
-        .as_ref()
-        .map(|artist| artist.name.clone())
-        .unwrap_or_else(|| "Unknown Artist".to_string());
-    let album_title = track
-        .album
-        .as_ref()
-        .map(|album| album.title.clone())
-        .unwrap_or_else(|| "Singles".to_string());
-
-    write_track_file(
-        &data,
-        &artist_name,
-        &album_title,
-        quality_dir,
-        track.track_number,
-        &track.title,
-        stream.format_id,
-        &stream.mime_type,
-        destination,
-    )
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;