From e69a5204dba098f66b0b63bde53846b8fc001821 Mon Sep 17 00:00:00 2001
From: Bryan Van Deusen <bryan.vandeusen@fabledsword.com>
Date: Wed, 3 Jun 2026 09:48:38 -0400
Subject: [PATCH] fix(android): PlayerController.setQueue dispatches to
 controller thread
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Crash on cold boot: ResumeController.restore is suspend, lands on
Dispatchers.Default after awaitReady() unblocks (drift #562), and
calls PlayerController.setQueue which calls MediaController.setMediaItems
— MediaController enforces application-thread access and throws
IllegalStateException 'method is called from a wrong thread'.

Drift #562 added awaitReady() to fix the race where setQueue
early-returned on null controller and silently dropped the persisted
queue. That fix exposed the next bug down the stack: the threading
violation that was previously masked by the early-return.

setQueue now posts the MediaController calls to the controller's
applicationLooper if we're not already on it. UI callers (already
Main) run inline with no re-dispatch latency. ResumeController's
cold-boot path lands on the right thread.

Discovered on-device 2026-06-03 during like-button verification on
the Pixel 6 Pro emulator — crash log at PlayerController.kt:190.
---
 .../minstrel/player/PlayerController.kt       | 25 ++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/android/app/src/main/java/com/fabledsword/minstrel/player/PlayerController.kt b/android/app/src/main/java/com/fabledsword/minstrel/player/PlayerController.kt
index 102bcba1..0604cd03 100644
--- a/android/app/src/main/java/com/fabledsword/minstrel/player/PlayerController.kt
+++ b/android/app/src/main/java/com/fabledsword/minstrel/player/PlayerController.kt
@@ -3,6 +3,8 @@ package com.fabledsword.minstrel.player
 import android.content.ComponentName
 import android.content.Context
 import android.os.Bundle
+import android.os.Handler
+import android.os.Looper
 import androidx.media3.common.MediaItem
 import androidx.media3.common.MediaMetadata
 import androidx.media3.common.Player
@@ -187,9 +189,26 @@ class PlayerController @Inject constructor(
         val controller = mediaController ?: return
         queueRefs = tracks
         val items = tracks.map { it.toMediaItem(source) }
-        controller.setMediaItems(items, initialIndex, /* startPositionMs = */ 0L)
-        controller.prepare()
-        if (autoplay) controller.play()
+        // Drift #562 cold-boot resume calls this from a non-Main suspend
+        // context after awaitReady() unblocks (ResumeController launches
+        // on Dispatchers.Default by the time it reaches us). MediaController
+        // enforces application-thread access and throws
+        // IllegalStateException otherwise — post to its applicationLooper
+        // if we're already there, run directly to avoid the re-dispatch
+        // latency UI callers depend on.
+        runOnControllerThread(controller) {
+            controller.setMediaItems(items, initialIndex, /* startPositionMs = */ 0L)
+            controller.prepare()
+            if (autoplay) controller.play()
+        }
+    }
+
+    private fun runOnControllerThread(controller: MediaController, block: () -> Unit) {
+        if (Looper.myLooper() == controller.applicationLooper) {
+            block()
+        } else {
+            Handler(controller.applicationLooper).post(block)
+        }
     }
 
     /**