Web player overhaul; iOS random sort, stems-only filter, pooled libraries

Web: live Stem Now status that tracks every queued song (albums too),
right-click menus with Stem Now, Songs and Genres pages, a Stems Only
filter in place of the sidebar section, Random sort, several pooled
Plex servers and libraries, themes plus custom CSS, a reorganised
settings page that loads without a refresh, saved mixes, karaoke and
synced lyrics, stem playlists and offline downloads.

iOS: Random in every sort menu, a Stems Only toggle (sort menu and
Settings), and several music libraries pooled from the signed-in server.
Settings now persists karaoke and speed across launches.

stemd writes a status file that stemserve serves at /api/queue.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/stemd.py

@@ -235,6 +235,43 @@ def resolve(plex_path):
     return path if os.path.splitext(path)[1].lower() in SOURCE_RANK else None
 
 
+class Status:
+    """What stemd is up to, for stemserve's /api/queue: the track in progress (the Plex path for
+    a Stem Now, else the path under MUSIC_DIR), how many tracks were finished since start, and the
+    last Stem Now paths that couldn't be done. Kept in QUEUE_DIR/.status.json, which the "*.json"
+    request glob skips because it starts with a dot."""
+
+    def __init__(self):
+        self.path = os.path.join(QUEUE_DIR, ".status.json")
+        self.current, self.done, self.failed = None, 0, []
+        self.write()
+
+    def start(self, current):
+        self.current = current
+        self.write()
+
+    def finish(self, ok, failed_path=None):
+        self.current = None
+        if ok:
+            self.done += 1
+        elif failed_path:
+            self.failed = [p for p in self.failed if p != failed_path][-49:] + [failed_path]
+        self.write()
+
+    def write(self):
+        tmp = self.path + ".tmp"
+        try:
+            with open(tmp, "w") as f:
+                json.dump({"current": self.current, "done": self.done, "failed": self.failed,
+                           "at": time.time()}, f)
+            os.replace(tmp, self.path)
+        except OSError:
+            pass
+
+
+status = None  # set in main()
+
+
 def serve_queue(sep, failed):
     """Separate every Stem Now request, oldest first. Returns whether any track was attempted.
 
@@ -257,6 +294,8 @@ def serve_queue(sep, failed):
             src = resolve(p) if isinstance(p, str) else None
             if src is None:
                 log(f"stem now: not in {MUSIC_DIR}: {p}")
+                if isinstance(p, str):
+                    status.finish(False, p)
                 continue
             dest = os.path.join(STEMS_DIR, os.path.splitext(os.path.relpath(src, MUSIC_DIR))[0])
             if is_done(dest):
@@ -267,17 +306,20 @@ def serve_queue(sep, failed):
                 continue
             if failed.skip(src, sig):
                 log(f"stem now: skip {os.path.relpath(src, MUSIC_DIR)}: failed before ({failed.data[src]['msg']})")
+                status.finish(False, p)
                 continue
-            todo.append((src, dest, sig))
+            todo.append((p, src, dest, sig))
         if todo:
             log(f"stem now: {len(todo)} track{'' if len(todo) == 1 else 's'} ahead of the rest")
-        for i, (src, dest, sig) in enumerate(todo, 1):
+        for i, (p, src, dest, sig) in enumerate(todo, 1):
             if stop.is_set():
                 return used
             if is_done(dest):
                 continue
             used = True
-            separate(sep, failed, src, dest, sig, f"[now {i}/{len(todo)}]")
+            status.start(p)
+            ok = separate(sep, failed, src, dest, sig, f"[now {i}/{len(todo)}]")
+            status.finish(ok, None if ok else p)
         if stop.is_set():
             break
         try:
@@ -316,7 +358,10 @@ def run_pass(sep, failed):
         if is_done(dest):  # a full pass takes days; the desktop or a Stem Now may have got there first
             continue
         used = True
-        if separate(sep, failed, path, dest, sig, f"[{i}/{len(todo)}]"):
+        status.start(os.path.relpath(path, MUSIC_DIR))
+        ok = separate(sep, failed, path, dest, sig, f"[{i}/{len(todo)}]")
+        status.finish(ok)
+        if ok:
             done += 1
     return done, used
 
@@ -347,6 +392,8 @@ def main():
         os.makedirs(QUEUE_DIR, exist_ok=True)
     except OSError as e:
         log(f"WARNING: can't create {QUEUE_DIR} ({e}); Stem Now won't work")
+    global status
+    status = Status()
     log(f"stemd: {MUSIC_DIR} -> {STEMS_DIR}")
     migrate_markers()
     sep = Separator()