android: the downloads say so in the shade

A Save still running with the app in the background now posts a progress
notice — how many files, the one it is on, a bar, Stop all and Open — and
takes it down when the queue empties. It sits on its own low-importance
channel so it can be silenced without silencing the player's card, and
rides its own dataSync foreground service rather than the media one: a
mediaPlayback service stops itself when the bar empties, a download is not
playback, and nothing else was keeping the process alive for a Save with
nothing playing — which is how the first real Save died, four tracks in.
Stop all goes through the same cancel(id) a row's tap takes, and Transfers
grew the matching button beside Clear finished. The walk pushes two rows
straight into the transfer store and reads the real notification back out
of `dumpsys notification`, without fetching anything.

src-tauri/Cargo.toml

@@ -60,6 +60,10 @@ audio-formats = { path = "../crates/audio-formats" }
 tauri-plugin-media-session = { path = "../crates/tauri-plugin-media-session" }
 tauri-plugin-storage = { path = "../crates/tauri-plugin-storage" }
 tauri-plugin-share = { path = "../crates/tauri-plugin-share" }
+# The phone's downloads notice (a second Kotlin foreground service, dataSync).
+# Registered everywhere so the permission set resolves on every platform; on
+# the desktop its commands answer "not here".
+tauri-plugin-transfer-notice = { path = "../crates/tauri-plugin-transfer-notice" }
 semver = "1"
 tauri-plugin-opener = "2.5.5"
 

src-tauri/build.rs

@@ -1,3 +1,8 @@
+// tauri-build only rewrites gen/android/tauri.settings.gradle and
+// app/tauri.build.gradle.kts — the lines that include every plugin's own
+// Android module — when this build script re-runs, so touch this file
+// whenever a plugin is added (ANDROID.md). The downloads notice was the
+// last one.
 fn main() {
     tauri_build::build()
 }

src-tauri/capabilities/default.json

@@ -23,6 +23,7 @@
     "media-session:default",
     "opener:default",
     "storage:default",
-    "share:default"
+    "share:default",
+    "transfer-notice:default"
   ]
 }

src-tauri/src/lib.rs

@@ -85,6 +85,10 @@ pub fn run() {
             app.handle().plugin(tauri_plugin_storage::init())?;
             // The share sheet on the phone: a link sent from another app lands in the import.
             app.handle().plugin(tauri_plugin_share::init())?;
+            // The downloads in the phone's shade: a progress notice on its own
+            // channel and its own dataSync service, so a Save survives the app
+            // going to the background with nothing playing.
+            app.handle().plugin(tauri_plugin_transfer_notice::init())?;
             #[cfg(desktop)]
             app.handle().plugin(tauri_plugin_updater::Builder::new().build())?;
             // Must run before anything touches the app-data dir.