feat: add key-free demo mode replaying recorded fixtures

backend/tests/test_demo_adapters.py

@@ -0,0 +1,68 @@
+"""Offline replay tests for demo service adapters."""
+
+import asyncio
+
+from app.adapters.demo.cassette import load_cassette
+from app.adapters.demo.catalog import DemoCatalog
+from app.adapters.demo.recommender import DemoRecommender
+from app.config import Settings
+
+
+def test_cassette_decodes_bodies_and_preserves_rerank_chunks() -> None:
+    cassette = load_cassette("focus-coding")
+
+    assert cassette.intent_response_body.startswith(b'{"model"')
+    assert len(cassette.spotify_search_responses) > 20
+    assert len(cassette.spotify_taste_responses) == 6
+    assert len(cassette.rerank_response_chunks) > 1
+    assert b"event: content_block_delta" in b"".join(cassette.rerank_response_chunks)
+
+
+def test_demo_catalog_replays_search_and_synthetic_taste_pages() -> None:
+    async def run() -> None:
+        catalog = DemoCatalog(load_cassette("focus-coding"))
+
+        tracks = await catalog.search_tracks('track:"Stay" artist:"Hybrid Minds"')
+        artists = await catalog.fetch_top_artists("short_term", 50)
+        top_tracks = await catalog.fetch_top_tracks("long_term", 50)
+        saved_tracks = await catalog.fetch_saved_tracks(100)
+
+        assert tracks[0].title == "Stay"
+        assert artists[0] == "Synthetic Focus Artist"
+        assert {track.title for track in top_tracks} >= {
+            "Synthetic Focus Track",
+            "Synthetic Jazz Track",
+        }
+        assert saved_tracks[0].title == "Synthetic Saved Track"
+
+    asyncio.run(run())
+
+
+def test_demo_recommender_parses_intent_and_streams_recorded_rerank() -> None:
+    async def run() -> None:
+        recommender = DemoRecommender(Settings(demo_chunk_delay_seconds=0))
+        intent = await recommender.create_intent(
+            "Focus while coding",
+            (),
+            (),
+            "Synthetic taste",
+            35,
+        )
+        selections = [
+            selection
+            async for selection in recommender.stream_rerank(
+                intent,
+                (),
+                "Synthetic taste",
+                (),
+                15,
+            )
+        ]
+
+        assert intent.activity == "programming"
+        assert len(intent.candidates) == 35
+        assert len(selections) == 15
+        assert selections[0].track_id == "2nIixNuuV5eHCJydG5aYIB"
+        assert all(selection.justification for selection in selections)
+
+    asyncio.run(run())