feat: add key-free demo mode replaying recorded fixtures

backend/tests/test_demo_scenario.py

@@ -0,0 +1,32 @@
+"""Tests for deterministic demo scenario selection."""
+
+from app.adapters.demo.scenario import select_replay_scenario, select_scenario
+
+
+def test_scenario_selection_prefers_normalized_exact_query_or_chip() -> None:
+    query_match = select_scenario("something calm for while I am programming, but not boring")
+    chip_match = select_scenario("  FOCUS, while CODING!  ")
+
+    assert query_match.key == "focus-coding"
+    assert query_match.is_exact
+    assert chip_match.key == "focus-coding"
+    assert chip_match.is_exact
+
+
+def test_scenario_selection_falls_back_to_nearest_fixture() -> None:
+    match = select_scenario("Focus while codign")
+
+    assert match.key == "focus-coding"
+    assert not match.is_exact
+
+
+def test_prior_results_select_a_matching_refinement_or_same_scenario() -> None:
+    refinement = select_replay_scenario("Focus while coding", True)
+    direct_refinement = select_replay_scenario("More electronic", False)
+    same_scenario = select_replay_scenario("Rainy Sunday", True)
+
+    assert refinement.key == "focus-coding-refine"
+    assert not refinement.is_exact
+    assert direct_refinement.key == "focus-coding-refine"
+    assert direct_refinement.is_exact
+    assert same_scenario.key == "rainy-sunday"