feat(player): identify songs on Linux from Harbor's own audio

.github/workflows/app-build.yml

@@ -53,6 +53,7 @@ jobs:
             libayatana-appindicator3-dev \
             libgtk-3-dev \
             libmpv-dev \
+            libpulse-dev \
             librsvg2-dev \
             libssl-dev \
             libudev-dev \

.github/workflows/ci.yml

@@ -136,6 +136,7 @@ jobs:
             libayatana-appindicator3-dev \
             libgtk-3-dev \
             libmpv-dev \
+            libpulse-dev \
             librsvg2-dev \
             libssl-dev \
             libudev-dev \

src-tauri/Cargo.toml

@@ -207,6 +207,7 @@ webview2-com = "0.39"
 [target.'cfg(target_os = "linux")'.dependencies]
 gtk = { version = "0.18", features = ["v3_24"] }
 zbus = { version = "5", default-features = false, features = ["tokio"] }
+libpulse-binding = "2.30"
 
 
 [dev-dependencies]

src-tauri/src/mpv.rs

@@ -429,6 +429,23 @@ fn mpv_header_field(name: &str, value: &str) -> String {
     format!("{name}: {value}").replace('\\', "\\\\").replace(',', "\\,")
 }
 
+// The PulseAudio client name is also how song_id identifies our playback on
+// Linux. Flatpak instances can share a sandbox PID, so PID alone cannot
+// distinguish their streams. A stable, per-process UUID avoids that collision.
+#[cfg(target_os = "linux")]
+pub(crate) fn audio_client_name() -> &'static str {
+    use std::sync::OnceLock;
+
+    static NAME: OnceLock<String> = OnceLock::new();
+    NAME.get_or_init(|| format!("Harbor {}", uuid::Uuid::new_v4().simple()))
+        .as_str()
+}
+
+#[cfg(not(target_os = "linux"))]
+pub(crate) fn audio_client_name() -> &'static str {
+    "Harbor"
+}
+
 fn apply_pre_init(
     init: &MpvInitializer,
     args: &MpvStartArgs,
@@ -459,7 +476,7 @@ fn apply_pre_init(
         .unwrap_or_default();
     let joined_init_only = join_init_only_pairs(&init_only_pairs);
     set("title", "Harbor");
-    set("audio-client-name", "Harbor");
+    set("audio-client-name", audio_client_name());
     set("terminal", "no");
     set("log-file", "");
     set("msg-level", "all=warn,vo=v,d3d11=v,gpu=v,win32=v");