fixed (bug) Audio output device not switching

src/audio/audio_manager.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "config/config_manager.h"
+#include <SDL3/SDL.h>
 #include <SDL3_mixer/SDL_mixer.h>
 #include <mutex>
 #include <string>
@@ -15,6 +16,7 @@ namespace radiantwave::audio {
 struct AudioDeviceItem {
     std::string raw_name;      // e.g. alsa_output.pci-0000_00_1f.3.analog-stereo
     std::string friendly_name; // e.g. "Built-In Speakers"
+    SDL_AudioDeviceID id = 0;  // SDL playback device id (0 = synthetic fallback)
 };
 
 // Maps raw technical audio device strings to user-friendly labels
@@ -51,7 +53,18 @@ public:
 
     // Audio device selection
     bool switchDevice(const std::string& raw_device_name);
+    bool switchDeviceById(SDL_AudioDeviceID id);
     std::string getCurrentDevice() const;
+    SDL_AudioDeviceID getCurrentDeviceId() const;
+
+    // Handle an SDL audio device event (SDL_EVENT_AUDIO_DEVICE_ADDED / REMOVED).
+    // Returns true if the active device was affected and the mixer was recreated.
+    bool handleDeviceEvent(const SDL_Event& event);
+
+    // Pure helper (no SDL audio open): find the playback device with the given
+    // SDL id, returning its raw name ("" when not found / id invalid). Exposed
+    // for tests; the real lookup is through getPlaybackDevices().
+    static std::string resolvePlaybackDeviceName(SDL_AudioDeviceID id);
 
     // Playback control
     bool playTrack(const std::string& wav_filename);
@@ -84,6 +97,13 @@ private:
     void startFadeIn(int slotIndex, float seconds);
     std::string displayNameFor(const std::string& wav_filename) const;
 
+    // Recreates the mixer on the given playback device id (0 = system default).
+    // Called with mutex_ held. Preserves playback state: whichever track was
+    // playing on the active slot is reloaded and resumed at full gain, an
+    // in-progress fade is restarted. Returns false on failure (previous mixer is
+    // left destroyed but the app remains safe to keep running muted).
+    bool recreateMixerOnDevice(SDL_AudioDeviceID targetId);
+
     config::ConfigManager* configManager_ = nullptr;
     db::DatabaseManager* db_ = nullptr;
 
@@ -91,6 +111,7 @@ private:
     bool enabled_ = true;
     int volume_ = 80; // 0 - 100
     std::string currentDevice_ = "";
+    SDL_AudioDeviceID currentDeviceId_ = SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK;
     std::string currentTrack_ = "";
 
     MIX_Mixer* mixer_ = nullptr;