From 8b7b9d8f3f5d8f1159e3ad210e9200b4762c3945 Mon Sep 17 00:00:00 2001
From: BoulderBadgeDad <batmanesignal@gmail.com>
Date: Sun, 7 Jun 2026 13:55:58 -0700
Subject: [PATCH] #809 review follow-up: crossfade preload also streams
 un-mounted Navidrome tracks
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Self-review of df929dc0 found one gap: the crossfade preloader hits
/stream/library-audio with the file PATH, which 404s for a streamed (not
disk-mounted) Navidrome track — main playback worked, crossfade didn't.
/stream/library-audio now uses the same _build_library_stream_url fallback on
a disk-miss (resolving the song id from the new track_id param, or a DB
lookup by path), and the preloader passes next.id. Crossfade now works for
streamed libraries too.

Review also confirmed (no change needed): /api/stream/status returns only
status/progress/track_info/error_message — the Subsonic token in stream_url
never reaches the browser; it stays server-side and the browser only hits
/stream/audio. Proxy verified live: Range forwarded, 206 + Content-Range/
Accept-Ranges passthrough, body streamed in 64KB chunks, upstream closed.
---
 web_server.py                | 6 ++++++
 webui/static/media-player.js | 5 ++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/web_server.py b/web_server.py
index 8c9c18aa..f18175fb 100644
--- a/web_server.py
+++ b/web_server.py
@@ -12547,6 +12547,12 @@ def stream_library_audio():
             return jsonify({"error": "path is required"}), 400
         resolved = _resolve_library_file_path(raw_path)
         if not resolved or not os.path.exists(resolved):
+            # Not on disk — same Navidrome stream fallback as /api/library/play
+            # (#809), so crossfade preload of the NEXT track works for streamed
+            # libraries too. Resolves the song id by path (DB lookup).
+            stream_url = _build_library_stream_url(request.args.get('track_id'), raw_path)
+            if stream_url:
+                return _proxy_stream_url_with_range(stream_url)
             return jsonify({"error": _get_file_not_found_error(raw_path)}), 404
         return _serve_audio_file_with_range(resolved)
     except Exception as e:
diff --git a/webui/static/media-player.js b/webui/static/media-player.js
index 4dff3642..4f155e92 100644
--- a/webui/static/media-player.js
+++ b/webui/static/media-player.js
@@ -1871,7 +1871,10 @@ function npStartCrossfade(nextIdx, next) {
 
     const targetVol = audioPlayer.volume; // fade the new track up to current level
     npXfadeMainVol = targetVol;            // remember to restore on abort
-    xa.src = `/stream/library-audio?path=${encodeURIComponent(next.file_path)}&t=${Date.now()}`;
+    // Pass the server song id so a streamed (un-mounted) Navidrome track can
+    // crossfade-preload via the server stream API too (#809).
+    const _xfTid = next.id ? `&track_id=${encodeURIComponent(next.id)}` : '';
+    xa.src = `/stream/library-audio?path=${encodeURIComponent(next.file_path)}${_xfTid}&t=${Date.now()}`;
     xa.volume = 0;
     xa.play().then(() => {
         const fadeMs = NP_CROSSFADE_SECONDS * 1000;