design: sync unliked tracks — remove from show and re-compact positions

Nick is the host; if he unlikes a track, the service should respect
that and remove it from the show playlist. Positions re-compact after
removal. The tracks table retains the record for historical reference.

Made-with: Cursor

docs/plans/2026-03-12-ntr-fetcher-implementation.md

@@ -579,6 +579,30 @@ def test_set_show_tracks_preserves_existing_positions(db):
     assert tracks[1]["position"] == 2
 
 
+def test_set_show_tracks_removes_unliked(db):
+    """Tracks no longer in the likes list are removed and positions re-compact."""
+    week_start = datetime(2026, 3, 13, 2, 0, 0, tzinfo=timezone.utc)
+    week_end = datetime(2026, 3, 20, 2, 0, 0, tzinfo=timezone.utc)
+    show = db.get_or_create_show(week_start, week_end)
+
+    t1 = _make_track(1, "2026-03-14T01:00:00+00:00", title="First")
+    t2 = _make_track(2, "2026-03-14T02:00:00+00:00", title="Second")
+    t3 = _make_track(3, "2026-03-14T03:00:00+00:00", title="Third")
+    db.upsert_track(t1)
+    db.upsert_track(t2)
+    db.upsert_track(t3)
+    db.set_show_tracks(show.id, [t1.id, t2.id, t3.id])
+
+    # Nick unlikes track 2
+    db.set_show_tracks(show.id, [t1.id, t3.id])
+    tracks = db.get_show_tracks(show.id)
+    assert len(tracks) == 2
+    assert tracks[0]["track_id"] == 1
+    assert tracks[0]["position"] == 1
+    assert tracks[1]["track_id"] == 3
+    assert tracks[1]["position"] == 2  # re-compacted from 3
+
+
 def test_get_show_track_by_position(db):
     week_start = datetime(2026, 3, 13, 2, 0, 0, tzinfo=timezone.utc)
     week_end = datetime(2026, 3, 20, 2, 0, 0, tzinfo=timezone.utc)
@@ -821,7 +845,12 @@ Add these methods to the `Database` class in `src/ntr_fetcher/db.py`:
         return dict(row) if row else None
 
     def set_show_tracks(self, show_id: int, track_ids: list[int]) -> None:
-        """Set show tracks, preserving positions of already-assigned tracks."""
+        """Sync show tracks to match track_ids list.
+
+        - Preserves positions of already-assigned tracks.
+        - Appends new tracks after the current max position.
+        - Removes tracks no longer in track_ids and re-compacts positions.
+        """
         conn = self._connect()
         existing = conn.execute(
             "SELECT track_id, position FROM show_tracks WHERE show_id = ? ORDER BY position",
@@ -829,6 +858,17 @@ Add these methods to the `Database` class in `src/ntr_fetcher/db.py`:
         ).fetchall()
         existing_map = {row["track_id"]: row["position"] for row in existing}
 
+        track_id_set = set(track_ids)
+
+        # Remove tracks that are no longer liked
+        removed = [tid for tid in existing_map if tid not in track_id_set]
+        for tid in removed:
+            conn.execute(
+                "DELETE FROM show_tracks WHERE show_id = ? AND track_id = ?",
+                (show_id, tid),
+            )
+
+        # Add new tracks at the end
         max_pos = max(existing_map.values()) if existing_map else 0
         for track_id in track_ids:
             if track_id not in existing_map:
@@ -837,6 +877,19 @@ Add these methods to the `Database` class in `src/ntr_fetcher/db.py`:
                     "INSERT OR IGNORE INTO show_tracks (show_id, track_id, position) VALUES (?, ?, ?)",
                     (show_id, track_id, max_pos),
                 )
+
+        # Re-compact positions if anything was removed
+        if removed:
+            rows = conn.execute(
+                "SELECT track_id FROM show_tracks WHERE show_id = ? ORDER BY position",
+                (show_id,),
+            ).fetchall()
+            for i, row in enumerate(rows, start=1):
+                conn.execute(
+                    "UPDATE show_tracks SET position = ? WHERE show_id = ? AND track_id = ?",
+                    (i, show_id, row["track_id"]),
+                )
+
         conn.commit()
         conn.close()
 
@@ -1418,6 +1471,46 @@ async def test_poll_once_fetches_and_stores():
     assert call_args[0][1] == [1, 2]  # track_ids in order
 
 
+@pytest.mark.asyncio
+async def test_poll_once_removes_unliked_tracks():
+    """When a track disappears from likes, it should be removed from the show."""
+    mock_sc = AsyncMock()
+    mock_sc.resolve_user.return_value = 206979918
+    # First poll: two tracks
+    mock_sc.fetch_likes.return_value = [
+        _make_track(1, "2026-03-14T01:00:00+00:00"),
+        _make_track(2, "2026-03-14T02:00:00+00:00"),
+    ]
+
+    mock_db = MagicMock()
+    mock_show = MagicMock()
+    mock_show.id = 1
+    mock_db.get_or_create_show.return_value = mock_show
+
+    poller = Poller(
+        db=mock_db,
+        soundcloud=mock_sc,
+        soundcloud_user="nicktherat",
+        show_day=2,
+        show_hour=22,
+        poll_interval=3600,
+    )
+
+    await poller.poll_once()
+
+    # Second poll: Nick unliked track 2
+    mock_sc.fetch_likes.return_value = [
+        _make_track(1, "2026-03-14T01:00:00+00:00"),
+    ]
+    mock_db.reset_mock()
+    mock_db.get_or_create_show.return_value = mock_show
+
+    await poller.poll_once()
+
+    call_args = mock_db.set_show_tracks.call_args
+    assert call_args[0][1] == [1]  # only track 1 remains
+
+
 @pytest.mark.asyncio
 async def test_poll_once_full_refresh():
     mock_sc = AsyncMock()