Raise coverage threshold to 95% and expand test coverage

- pyproject.toml: fail_under 80 → 95
- test_alpha: +79 lines
- test_cli_workflow: +226 lines
- test_derived: +121 lines
- test_downloader_contracts: +169 lines
- test_features: +16 lines
- test_minute_downloader: +81 lines
- test_portfolio: +208 lines

tests/test_alpha.py

@@ -191,6 +191,15 @@ def test_combine_single_alpha_is_identity(tmp_path):
     assert (combo["combo_name"] == "rev_combo").all()
 
 
+def test_combine_alphas_rejects_unknown_method(tmp_path):
+    data = _make_data()
+    alpha_path = tmp_path / "alpha.pq"
+    compute_alpha(data, "rev", "reversal", lookback=5).to_parquet(alpha_path, index=False)
+
+    with pytest.raises(ValueError, match="Unknown combo method"):
+        combine_alphas([str(alpha_path)], "bad_combo", method="does_not_exist")
+
+
 # --- registry / factory -----------------------------------------------------
 
 def test_builtins_are_registered():
@@ -205,6 +214,22 @@ def test_get_alpha_filters_unaccepted_params():
     assert not hasattr(alpha, "vol_window")
 
 
+def test_get_alpha_forwards_kwargs_to_flexible_alpha():
+    @register_alpha
+    class _FlexibleAlpha(BaseAlpha):
+        name = "_flexible_alpha_kwargs"
+
+        def __init__(self, **kwargs):
+            self.kwargs = kwargs
+
+        def signal(self, close):
+            return close
+
+    alpha = get_alpha("_flexible_alpha_kwargs", decay=0.5, label="demo")
+
+    assert alpha.kwargs == {"decay": 0.5, "label": "demo"}
+
+
 def test_get_alpha_unknown_raises():
     with pytest.raises(KeyError):
         get_alpha("does_not_exist")
@@ -227,6 +252,31 @@ def test_register_rejects_non_basealpha():
         register_alpha(object)  # type: ignore[arg-type]
 
 
+def test_register_rejects_empty_alpha_name():
+    with pytest.raises(ValueError, match="non-empty"):
+        @register_alpha
+        class NoNameAlpha(BaseAlpha):
+            def signal(self, close):
+                return close
+
+
+def test_load_alpha_module_error_paths(tmp_path, monkeypatch):
+    missing_path = tmp_path / "missing_alpha.py"
+    with pytest.raises(FileNotFoundError):
+        load_alpha_module(str(missing_path))
+
+    bad_path = tmp_path / "bad_alpha.py"
+    bad_path.write_text("x = 1\n")
+    monkeypatch.setattr(
+        "pipeline.alpha.registry.importlib.util.spec_from_file_location",
+        lambda *args, **kwargs: None,
+    )
+    with pytest.raises(ImportError, match="Cannot load alpha module"):
+        load_alpha_module(str(bad_path))
+
+    load_alpha_module("math")
+
+
 # --- base class --------------------------------------------------------------
 
 def test_to_weights_are_per_date_zscore():
@@ -242,6 +292,20 @@ def test_to_weights_are_per_date_zscore():
     assert (weights.mean(axis=1).abs() < 1e-9).all()
 
 
+def test_base_alpha_default_signal_and_repr():
+    alpha = BaseAlpha()
+    alpha.example = 3
+
+    with pytest.raises(NotImplementedError, match="signal"):
+        alpha.signal(pd.DataFrame({"x": [1.0]}))
+    with pytest.raises(NotImplementedError, match="signal"):
+        alpha.signal_from_data(
+            pd.DataFrame({"symbol_id": ["sh600000"]}),
+            pd.DataFrame({"sh600000": [1.0]}),
+        )
+    assert repr(alpha) == "BaseAlpha(example=3)"
+
+
 # --- external plugin loading -------------------------------------------------
 
 def test_load_external_alpha_module(tmp_path):
@@ -502,3 +566,18 @@ def test_compute_alpha_rejects_feature_path_collision_with_daily_data(tmp_path):
             "reversal",
             feature_paths=[str(close_collision_path)],
         )
+
+
+def test_evaluate_alpha_empty_when_signal_dates_not_on_market_calendar():
+    data = _make_data(n_days=3)
+    alpha = pd.DataFrame({
+        "symbol_id": ["sh600000"],
+        "date": [pd.Timestamp("2030-01-01")],
+        "alpha_name": ["future"],
+        "weight": [1.0],
+    })
+
+    metrics = evaluate_alpha(alpha, data)
+
+    assert metrics["n_dates"] == 0
+    assert metrics["cumulative_return"] == 0.0