Audio playback failed against the prod HTTPS server with
"Cleartext HTTP traffic to 127.0.0.1 not permitted". Diagnostic
logging confirmed _baseUrl was correctly set to the prod URL — the
127.0.0.1 wasn't coming from the server or our URL construction.
Root cause: just_audio + audio_service spin up a local HTTP proxy on
loopback to inject the Authorization header, because Android's
MediaSession API can't pass headers down to ExoPlayer directly.
ExoPlayer connects to http://127.0.0.1:<random-port>; the proxy adds
the Bearer header and forwards to the real upstream HTTPS URL.
Loopback traffic doesn't leave the device.
This is the documented just_audio happy path — see
https://pub.dev/packages/just_audio#a-note-on-android-cleartext-traffic
— not a workaround for a plugin bug.
Adds network_security_config.xml that scopes cleartext permission to
127.0.0.1 ONLY. The base config keeps cleartextTrafficPermitted=false
so any actual remote endpoint must still be HTTPS.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>