fix(ui): keep Bandcamp link across history refreshes

somafm_tui/app.py

@@ -139,6 +139,7 @@ class SomaFMApp(App[None]):
         self.artwork_bytes: bytes | None = None
         self._art_track_key = ""
         self._bandcamp_key = ""
+        self._bandcamp_urls: dict[str, str] = {}
         self._http: httpx.AsyncClient | None = None
         self._closed = False
         self._tick_timer = None
@@ -376,6 +377,10 @@ class SomaFMApp(App[None]):
         previous = station.now_playing
         station.history = songs
         station.now_playing = songs[0]
+        if previous is not None and previous.key() == songs[0].key():
+            # History refreshes replace the Song object even when the track has
+            # not changed.  Keep the asynchronously discovered Bandcamp link.
+            songs[0].bandcamp_url = previous.bandcamp_url
         changed = previous is None or previous.key() != songs[0].key()
         if self.current is not None and self.current.id == station_id:
             if changed:
@@ -432,13 +437,24 @@ class SomaFMApp(App[None]):
     def _update_bandcamp(self) -> None:
         """Find a Bandcamp track link once per now-playing track."""
         station = self.current
-        if station is None or self.offline or self._http is None:
+        if station is None:
             return
         song = station.now_playing
         if song is None or not (song.artist.strip() or song.title.strip()):
             return
 
         track_key = f"{station.id}|{song.key()}"
+        cached_url = self._bandcamp_urls.get(track_key)
+        if cached_url:
+            self._bandcamp_key = track_key
+            if song.bandcamp_url != cached_url:
+                song.bandcamp_url = cached_url
+                with contextlib.suppress(NoMatches):
+                    self.query_one(StagePanel).refresh_stage()
+            return
+
+        if self.offline or self._http is None:
+            return
         if track_key == self._bandcamp_key:
             return
         self._bandcamp_key = track_key
@@ -461,6 +477,7 @@ class SomaFMApp(App[None]):
         if not url:
             return
 
+        self._bandcamp_urls[f"{station_id}|{song_key}"] = url
         station = next((s for s in self.stations if s.id == station_id), None)
         if station is None or self.current is None or self.current.id != station_id:
             return
@@ -822,6 +839,7 @@ class SomaFMApp(App[None]):
     def action_refresh(self) -> None:
         self._last_history_fetch = 0.0
         self._bandcamp_key = ""
+        self._bandcamp_urls.clear()
         self._set_notice("refreshing…", 2)
         if self.offline:
             self._set_notice("offline mode — nothing to refresh", 3)

tests/test_app.py

@@ -159,6 +159,63 @@ async def test_stage_shows_bandcamp_link_only_when_present() -> None:
         assert "Bandcamp" not in rendered_text(app)
 
 
+@pytest.mark.asyncio
+async def test_bandcamp_link_survives_history_refresh(monkeypatch) -> None:
+    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    async with app.run_test(size=(110, 40)) as pilot:
+        await pilot.pause()
+        station = app.current
+        assert station is not None
+        url = "https://jensbuchert.bandcamp.com/track/rauschebart"
+        old_song = Song(
+            title="Rauschebart",
+            artist="Jens Buchert",
+            album="Gravity",
+            bandcamp_url=url,
+        )
+        station.now_playing = old_song
+        station.history = [old_song]
+
+        async def fake_fetch_history(client, station_id):
+            assert station_id == station.id
+            return [
+                Song(
+                    title="Rauschebart",
+                    artist="Jens Buchert",
+                    album="Gravity",
+                )
+            ]
+
+        monkeypatch.setattr("somafm_tui.app.api.fetch_history", fake_fetch_history)
+        worker = app._fetch_history(station.id)
+        await worker.wait()
+        await pilot.pause()
+
+        assert station.now_playing is not None
+        assert station.now_playing is not old_song
+        assert station.now_playing.bandcamp_url == url
+        assert "Bandcamp" in rendered_text(app)
+
+
+@pytest.mark.asyncio
+async def test_cached_bandcamp_link_is_reapplied_to_new_song() -> None:
+    app = SomaFMApp(autoplay=False, offline=True, audio=False)
+    async with app.run_test(size=(110, 40)) as pilot:
+        await pilot.pause()
+        station = app.current
+        assert station is not None
+        url = "https://jensbuchert.bandcamp.com/track/rauschebart"
+        song = Song(title="Rauschebart", artist="Jens Buchert", album="Gravity")
+        app._bandcamp_urls[f"{station.id}|{song.key()}"] = url
+        station.now_playing = song
+
+        app._update_bandcamp()
+        await pilot.pause()
+
+        assert song.bandcamp_url == url
+        assert "Bandcamp" in rendered_text(app)
+
+
 @pytest.mark.asyncio
 async def test_media_session_commands_drive_the_app() -> None:
     app = SomaFMApp(autoplay=False, offline=True, audio=False)