multi player / per user playing and translation

scribblings/rkt-web-player.scrbl

@@ -26,6 +26,7 @@ browser by Racket's web server.
           [#:listen-ip listen-ip string? "127.0.0.1"]
           [#:port port exact-positive-integer? 8080]
           [#:dlna-port dlna-port exact-positive-integer? 8734]
+          [#:local-output? local-output? boolean? #t]
           [#:playlist-keystore playlist-keystore (or/c path-string? #f)]
           [#:launch-browser? launch-browser? boolean? #t]) any/c] {
 
@@ -39,11 +40,19 @@ contents are browsed one level at a time. Metadata and recursive contents are
 only read when the user adds or plays a selected item.
 
 The @racket[dlna-port] is used to publish local audio files to a selected
-network renderer. Playlist tabs are atomically persisted in
+network renderer. Set @racket[local-output?] to @racket[#f] to omit the
+server's own @tt{racket-audio} output. When no other renderer is available, the
+player waits for discovery or playback-agent registration. Playlist tabs are
+atomically persisted in
 @racket[playlist-keystore]; @racket[#f] disables playlist persistence. Player
 resources are closed when the web server exits. The default is
 @tt{data/playlists.keystore} below the installed rkt-web-player collection.
 Each username owns an ordered GUID index and separate playlist values.
+It also owns an independent playback pipeline and a durable interface-language
+preference. Different outputs can play concurrently. Selecting an output that
+another user owns stops the previous backend and transfers that output. The web
+interface supports Dutch, English, German, French and Spanish; browser language
+is the initial default and a manual choice is stored per username.
 When @racket[users] is non-empty, every browser client must authenticate.
 Sessions have a sliding idle timeout; an active browser cookie is renewed once
 half of @racket[session-seconds] has elapsed. Playback-agent endpoints continue
@@ -77,6 +86,8 @@ configured RKT Web Player server, downloads assigned tracks over HTTP, and
 plays them with @tt{racket-audio}. Its configured display name is authoritative
 and is followed by the server. Importing the module does not start the GUI; the
 function must be called explicitly.
+The GUI and optional tray use Dutch, English, German, French or Spanish based
+on the operating-system language, with English as fallback.
 }
 
 @defproc[(run-player-agent-cli [#:server-url server-url