Add regression test for scrobble payload fields

Verify that scrobble payloads do not include undocumented app_version,
app_date, or date fields that can cause 400 responses from the Trakt API.

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: glensc

tests/test_scrobble.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+from unittest.mock import patch
+
 from trakt.movies import Movie
 from trakt.sync import Scrobbler
 
@@ -22,3 +24,28 @@ def test_scrobbler_context_manager():
     with Scrobbler(guardians, 0.0, '1.0.0', '2015-02-01') as scrob:
         for i in range(10):
             scrob.update(i*10)
+
+
+def test_scrobbler_payload_excludes_app_metadata():
+    """scrobble payload must not include undocumented app_version/date fields"""
+    import trakt.core
+    guardians = Movie('Guardians of the Galaxy', year=2014)
+    scrobbler = Scrobbler(guardians, 42.0, '1.0.0', '2015-02-01')
+
+    with patch.object(trakt.core.api(), 'post', return_value=None) as mock_post:
+        scrobbler.start()
+
+    print("call_args:", mock_post.call_args)
+    print("args:", getattr(mock_post.call_args, "args", None))
+    print("tuple:", tuple(mock_post.call_args))
+
+    args, kwargs = mock_post.call_args
+    assert not kwargs
+    assert len(args) >= 2
+    payload = args[-1]
+
+    assert isinstance(payload, dict)
+    assert payload['progress'] == 42.0
+    assert 'app_version' not in payload
+    assert 'app_date' not in payload
+    assert 'date' not in payload