ML-008: add statistical baseline model

Closes #19

tests/api/test_ml_routes.py

@@ -87,12 +87,16 @@ def test_retrain_creates_and_replaces_persisted_model(tmp_path: Path) -> None:
     assert created.json() == {
         "model_id": "home-model",
         "supported_sensors": ["sensor.kitchen"],
+        "trained_features": 1,
+        "model_type": "statistical_baseline",
         "replaced": False,
     }
     assert replaced.status_code == 200
     assert replaced.json() == {
         "model_id": "home-model",
         "supported_sensors": ["sensor.bedroom"],
+        "trained_features": 1,
+        "model_type": "statistical_baseline",
         "replaced": True,
     }
     restarted = ModelRegistry(tmp_path)
@@ -107,3 +111,70 @@ def test_retrain_rejects_empty_samples() -> None:
         )
 
     assert response.status_code == 422
+
+
+def test_predict_returns_numeric_forecast_and_confidence(tmp_path: Path) -> None:
+    from app.ml.feature_store import FeatureStore, FeatureVector
+    from app.ml.registry.model_registry import ModelRegistry
+    from app.ml.training import TrainingPipeline
+
+    store = FeatureStore()
+    store.add_batch(
+        [
+            FeatureVector("sensor.kitchen", {"temperature": 19.0}),
+            FeatureVector("sensor.kitchen", {"temperature": 20.0}),
+        ]
+    )
+    registry = ModelRegistry(tmp_path)
+    registry.register(TrainingPipeline(store).run("home-model"))
+
+    with TestClient(app) as client:
+        app.state.registry = registry
+        response = client.post(
+            "/ml/predict",
+            json={
+                "modelId": "home-model",
+                "sensor_id": "sensor.kitchen",
+                "values": {"temperature": 21.0},
+            },
+        )
+
+    assert response.status_code == 200
+    assert response.json()["predictions"] == {"temperature": 22.0}
+    assert 0.0 < response.json()["confidence"] <= 1.0
+    assert response.json()["model_type"] == "statistical_baseline"
+
+
+def test_evaluate_returns_real_error_metrics(tmp_path: Path) -> None:
+    from app.ml.feature_store import FeatureStore, FeatureVector
+    from app.ml.registry.model_registry import ModelRegistry
+    from app.ml.training import TrainingPipeline
+
+    store = FeatureStore()
+    store.add_batch(
+        [
+            FeatureVector("sensor.kitchen", {"temperature": 19.0}),
+            FeatureVector("sensor.kitchen", {"temperature": 20.0}),
+        ]
+    )
+    registry = ModelRegistry(tmp_path)
+    registry.register(TrainingPipeline(store).run("home-model"))
+
+    with TestClient(app) as client:
+        app.state.registry = registry
+        response = client.post(
+            "/ml/evaluate",
+            json={
+                "modelId": "home-model",
+                "samples": [
+                    {
+                        "sensor_id": "sensor.kitchen",
+                        "values": {"temperature": 21.0},
+                    }
+                ],
+            },
+        )
+
+    assert response.status_code == 200
+    metrics = {metric["name"]: metric["value"] for metric in response.json()["metrics"]}
+    assert metrics == {"mae": 1.0, "rmse": 1.0, "coverage": 1.0}