fix(player+lidarr): mini-player sync race; durable approve + dedup

player: setQueueFromTracks fast-starts a single source at player-index 0
while the full queue is broadcast, so the transient currentIndexStream→0
emission clobbered the correct mediaItem with queue.value[0] (the first
track). Mini bar / playlist marker pinned to the wrong track until a
later index event (~the "passive ~30s recovery"). Track a logical-index
base so the player→queue mapping stays correct during the fill window;
also fixes the latent forward-fill auto-advance off-by-base.

lidarr #50: approving no longer fails when Lidarr is down. Approve
records the decision durably first, then best-effort adds; the
reconciler idempotently (re)sends unconfirmed adds every tick until they
stick (new additive lidarr_add_confirmed_at; AddArtist/AddAlbum map
Lidarr's "already exists" 400 → ErrAlreadyExists). No failed-state or
expiry by design — Lidarr keeps trying, operator monitors.

lidarr #51: Create() is now idempotent — a non-terminal request for the
same MBID returns the existing row instead of inserting a duplicate.

Rewrites the obsolete LidarrUnreachable_503 test to assert the durable-
approve contract; threads a client factory into NewReconciler.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

flutter_client/lib/player/audio_handler.dart

@@ -74,6 +74,20 @@ class MinstrelAudioHandler extends BaseAudioHandler with QueueHandler, SeekHandl
   /// new queue, leaving the player "locked" to a corrupted state.
   int _queueGeneration = 0;
 
+  /// Logical-queue index that just_audio player-index 0 currently maps
+  /// to. setQueueFromTracks fast-starts with a SINGLE source at player
+  /// index 0 while queue.value already holds the full list, so the
+  /// playing track's logical index is clampedInitial, not 0. The
+  /// transient currentIndexStream→0 emission that arrives just after
+  /// setAudioSources resolves (and after _suppressIndexUpdates is back
+  /// to false) would otherwise make _onCurrentIndexChanged broadcast
+  /// queue.value[0] — the FIRST track — over the correct item, pinning
+  /// the mini bar / playlist marker to the wrong track until a later
+  /// index event. Decremented in lockstep with the backward fill's
+  /// front inserts so player-index → logical-index stays correct and
+  /// lands at 0 once the player list fully matches queue.value.
+  int _logicalIndexBase = 0;
+
   /// Tracks the most recent setQueueFromTracks() input so
   /// skipToQueueItem can reconstruct the source list. just_audio
   /// requires every source to be built before it can be a skip
@@ -178,6 +192,11 @@ class MinstrelAudioHandler extends BaseAudioHandler with QueueHandler, SeekHandl
     _suppressIndexUpdates = true;
     try {
       await _player.setAudioSources([initial], initialIndex: 0);
+      // Player-index 0 holds the single fast-start source, which is
+      // logical-queue index clampedInitial. Record the offset before
+      // broadcasting so the post-resolve currentIndexStream→0 emission
+      // maps back to the correct item instead of queue.value[0].
+      _logicalIndexBase = clampedInitial;
       // Broadcast in this order: queue first (so any consumer that
       // reacts to mediaItem and reads queue.value sees the consistent
       // pair), then mediaItem.
@@ -242,6 +261,11 @@ class MinstrelAudioHandler extends BaseAudioHandler with QueueHandler, SeekHandl
           final src = await _buildAudioSource(tracks[i]);
           if (gen != _queueGeneration) return;
           await _player.insertAudioSource(i, src);
+          // Each front insert shifts the playing source's player index
+          // up by one; drop the base in lockstep so player-index →
+          // logical-index stays correct (and reaches 0 once the player
+          // list fully matches queue.value).
+          _logicalIndexBase -= 1;
         }
       } catch (e) {
         debugPrint('audio_handler: backward fill failed: $e');
@@ -447,8 +471,15 @@ class MinstrelAudioHandler extends BaseAudioHandler with QueueHandler, SeekHandl
     // track was passed via setQueueFromTracks(initialIndex:) regardless
     // of skip/auto-advance.
     final items = queue.value;
-    if (idx >= 0 && idx < items.length) {
-      mediaItem.add(items[idx]);
+    // Map the just_audio player index back to the logical queue index.
+    // During the fast-start/fill window the player list is a moving
+    // window offset from queue.value by _logicalIndexBase; mapping the
+    // raw player index straight in here is what previously broadcast
+    // queue.value[0] (the first track) over the correct item on every
+    // fast-start with initialIndex > 0.
+    final logical = idx + _logicalIndexBase;
+    if (logical >= 0 && logical < items.length) {
+      mediaItem.add(items[logical]);
     }
     unawaited(_loadArtForCurrentItem());
   }