fix(tui): clear now-playing metadata on a null metadata payload

sendspin/tui/app.py

@@ -139,6 +139,20 @@ def update_metadata(self, metadata: SessionUpdateMetadata) -> bool:
 
         return changed
 
+    def clear_metadata(self) -> bool:
+        """Clear all now-playing metadata and report whether anything changed.
+
+        A bare ``metadata: null`` in a server/state message is a spec-legal
+        clear (an absent field would be ``UndefinedField`` instead), so the
+        previous track must not be left on screen.
+        """
+        changed = False
+        for attr in ("title", "artist", "album", "track_progress", "track_duration"):
+            if getattr(self, attr) is not None:
+                setattr(self, attr, None)
+                changed = True
+        return changed
+
     def describe(self) -> str:
         """Return a human-friendly description of the current state."""
         lines: list[str] = []
@@ -811,7 +825,14 @@ def _handle_metadata_update(self, payload: ServerStatePayload) -> None:
         ui = self._ui
         if isinstance(payload.metadata, UndefinedField):
             return
-        if payload.metadata is None or not state.update_metadata(payload.metadata):
+        if payload.metadata is None:
+            # A bare ``metadata: null`` is a spec-legal clear -- an absent field
+            # is UndefinedField and handled above -- so drop the stale
+            # now-playing fields instead of leaving the previous track on screen.
+            changed = state.clear_metadata()
+        else:
+            changed = state.update_metadata(payload.metadata)
+        if not changed:
             return
 
         with ui.batch_update():

tests/tui/test_metadata_clear.py

@@ -0,0 +1,53 @@
+"""Tests for the TUI metadata-clear handling."""
+
+from __future__ import annotations
+
+import contextlib
+from types import SimpleNamespace
+from typing import Any
+
+from sendspin.tui.app import AppState, SendspinApp
+
+
+def _fake_ui() -> SimpleNamespace:
+    return SimpleNamespace(
+        batch_update=contextlib.nullcontext,
+        set_metadata=lambda **kwargs: None,
+        set_progress=lambda *args: None,
+        set_repeat_shuffle=lambda *args: None,
+        add_event=lambda *args: None,
+    )
+
+
+def _app_with(state: AppState) -> Any:
+    return SimpleNamespace(_ui=_fake_ui(), _state=state)
+
+
+def test_app_state_clear_metadata_resets_now_playing() -> None:
+    state = AppState(
+        title="Track",
+        artist="Artist",
+        album="Album",
+        track_progress=1000,
+        track_duration=5000,
+    )
+
+    assert state.clear_metadata() is True
+    assert state.title is None
+    assert state.artist is None
+    assert state.album is None
+    assert state.track_progress is None
+    assert state.track_duration is None
+    # Clearing an already-clear state reports no change.
+    assert state.clear_metadata() is False
+
+
+def test_handle_metadata_update_clears_on_null_payload() -> None:
+    """A spec-legal metadata clear must not leave stale now-playing text behind."""
+    state = AppState(title="Track", artist="Artist", album="Album")
+
+    SendspinApp._handle_metadata_update(_app_with(state), SimpleNamespace(metadata=None))
+
+    assert state.title is None
+    assert state.artist is None
+    assert state.album is None