ok

private/server.rkt

@@ -101,12 +101,18 @@
 (define (request-username auth request)
   (or (auth-request-user auth request) "anonymous"))
 
-;;; Returns the player state belonging to the requesting user.
+;;; Read the opaque version of the playlist already held by this browser.
+(define (request-playlist-version request)
+  (let ((entry (assq 'playlistVersion (url-query (request-uri request)))))
+    (and entry (cdr entry))))
+
+;;; Returns user state, including tracks only when this browser needs them.
 (define (state-handler player auth request)
   (json-response
    (player-state->jsexpr
     player
-    #:username (request-username auth request))))
+    #:username (request-username auth request)
+    #:playlist-version (request-playlist-version request))))
 
 ;;; Starts renderer discovery and returns the updated player state.
 (define (discover-handler player auth request)
@@ -114,7 +120,8 @@
   (json-response
    (player-state->jsexpr
     player
-    #:username (request-username auth request))))
+    #:username (request-username auth request)
+    #:playlist-version (request-playlist-version request))))
 
 ;;; Applies one player command for the requesting user.
 (define (command-handler player auth request command)
@@ -125,7 +132,8 @@
       player
       command
       (request-jsexpr request)
-      #:username (request-username auth request)))))
+      #:username (request-username auth request)
+      #:playlist-version (request-playlist-version request)))))
 
 ;;; Returns the persisted interface preferences for the requesting user.
 (define (preferences-handler player auth request)
@@ -405,6 +413,31 @@
   (check-equal?
    (request-jsexpr (test-request #"POST" "/api/preferences"))
    (hasheq))
+  (test-case "HTTP state and commands accept the browser's playlist version"
+    (let* ((value (make-player '() #:playlist-keystore #f #:local-output? #f))
+           (auth (make-auth-manager '()))
+           (dispatch (make-dispatch value auth)))
+      (dynamic-wind
+        void
+        (λ ()
+          (let* ((full (response-jsexpr (dispatch (test-request #"GET" "/api/state"))))
+                 (version (hash-ref full 'playlistVersion))
+                 (compact
+                  (response-jsexpr
+                   (dispatch (test-request #"GET" (string-append "/api/state?playlistVersion=" version))))))
+            (check-equal? (hash-ref full 'tracks) '())
+            (check-eq? (hash-ref compact 'tracks) 'null)
+            (check-equal? (hash-ref compact 'playlistVersion) version)
+            (let ((renamed
+                   (response-jsexpr
+                    (dispatch
+                     (test-request #"POST"
+                                   (string-append "/api/command/tab-rename?playlistVersion=" version)
+                                   #:headers (list (header #"Content-Type" #"application/json"))
+                                   #:body #"{\"index\":0,\"name\":\"Music\"}")))))
+              (check-eq? (hash-ref renamed 'tracks) 'null)
+              (check-equal? (hash-ref (car (hash-ref renamed 'tabs)) 'name) "Music"))))
+        (λ () (player-close! value)))))
   (check-equal?
    (request-jsexpr
     (test-request #"POST"