SplitAudio is alpha. Please read the limits below before relying on it.

• The routing helper (route/AppRoute.java) runs as the shell user (started through Shizuku). That is what lets it register a system audio policy (MODIFY_AUDIO_ROUTING).
• The app writes approute.dex / approute.sh into /data/local/tmp and runs them there. Anything else that already has shell access could replace those files — this is the same trust level as shell/Shizuku itself, not an extra hole.
• The accessibility service filters volume keys and reads only the foreground package name (rootInActiveWindow.packageName). It is declared with canRetrieveWindowContent because Android requires that for rootInActiveWindow; screen text is never read.

• The helper listens on 127.0.0.1:47821 only (not reachable from the network), with no authentication.
• Commands: state → on/off; vol up|down <package> → changes the phone speaker volume by one step, only while the rule is on and only for apps that are being routed to the speaker.
• Any app on the same phone could therefore read the on/off state or nudge the speaker volume. It cannot change which apps are routed, stop the helper, or run commands. Input is parsed strictly; nothing is passed to a shell.

• Native AudioPolicy keeps at most 20 uids per mix and 50 mixes per policy → at most 1000 app uids are routed; any extra apps stay on Bluetooth (user-installed apps are listed first).
• The music app list is hard-coded (YouTube Music + Morphe build). Other music apps need a code change.
• Verified on one device (Xiaomi 15, HyperOS 3, Android 16). Other ROMs may ignore or reject the policy; if the helper dies or the policy is rejected, audio simply stays on Bluetooth.
• Apps installed after routing started are not included until the next start (music stop → start again).

Please open a GitHub issue. There is no network-facing component, so there is no private disclosure channel.