feat(backend): expose GET /api/v1/alerts

Consultation des alertes de consommation, filtrable par site_id et
severity a l'identique du contrat GET /alerts de l'API Mock. Reprend
le gabarit endpoints -> services -> repositories -> models pose par
sites, sur la table alert deja creee par la revision Alembic
e6d2026091501.

Generalise aussi le garde-fou OpenAPI du 403 (ROUTES_A_ROLE) au-dela
du seul tag users, pour que l'ajout d'alerts a la liste des routes
protegees par role soit reellement verifie.

Closes #59

apps/backend/tests/api/test_alerts.py

@@ -0,0 +1,136 @@
+from collections.abc import Callable, Iterator
+from datetime import UTC, datetime
+from uuid import uuid4
+
+import pytest
+from fastapi import FastAPI
+from httpx import AsyncClient
+
+from app.api.deps import get_alert_service, get_current_principal
+from app.core.principal import Principal
+from app.core.roles import AccountKind, Role
+from app.models.energy import Alert
+
+
+def principal(role: Role = Role.LECTEUR) -> Principal:
+    return Principal(
+        id=uuid4(),
+        email=f"{role.value}@enervision.fr",
+        role=role,
+        kind=AccountKind.HUMAIN,
+        must_change_password=False,
+    )
+
+
+def alert(alert_id: int = 1, site_id: str = "site-1", severity: str = "high") -> Alert:
+    return Alert(
+        alert_id=alert_id,
+        source_alert_id=f"ALR-{alert_id}",
+        site_id=site_id,
+        source="enervision",
+        timestamp=datetime(2026, 9, 16, tzinfo=UTC),
+        type="threshold",
+        severity=severity,
+        message="Dépassement du seuil configuré",
+        value=812.5,
+        threshold=720.0,
+        metric="consumption_kw",
+        prediction_id=None,
+        raw_data={},
+    )
+
+
+class FauxService:
+    def __init__(self) -> None:
+        self.alert = alert()
+        self.appels: list[tuple[str | None, str | None]] = []
+
+    async def list_all(
+        self, *, site_id: str | None = None, severity: str | None = None
+    ) -> list[Alert]:
+        self.appels.append((site_id, severity))
+        return [self.alert]
+
+
+@pytest.fixture
+def lecteur_connecte(app: FastAPI) -> Iterator[None]:
+    app.dependency_overrides[get_current_principal] = lambda: principal()
+    yield
+    app.dependency_overrides.pop(get_current_principal, None)
+
+
+@pytest.fixture
+def servi(app: FastAPI, lecteur_connecte: None) -> Iterator[Callable[[], FauxService]]:
+    def installe() -> FauxService:
+        service = FauxService()
+        app.dependency_overrides[get_alert_service] = lambda: service
+        return service
+
+    yield installe
+    app.dependency_overrides.pop(get_alert_service, None)
+
+
+async def test_list_alerts_returns_the_alerts(
+    servi: Callable[[], FauxService], client: AsyncClient
+) -> None:
+    servi()
+
+    response = await client.get("/api/v1/alerts")
+
+    assert response.status_code == 200
+    corps = response.json()
+    assert corps == [
+        {
+            "alert_id": 1,
+            "site_id": "site-1",
+            "timestamp": "2026-09-16T00:00:00Z",
+            "type": "threshold",
+            "severity": "high",
+            "message": "Dépassement du seuil configuré",
+            "value": 812.5,
+            "threshold": 720.0,
+            "metric": "consumption_kw",
+            "prediction_id": None,
+        }
+    ]
+
+
+async def test_list_alerts_transmits_the_site_id_filter(
+    servi: Callable[[], FauxService], client: AsyncClient
+) -> None:
+    service = servi()
+
+    await client.get("/api/v1/alerts?site_id=site-1")
+
+    assert service.appels == [("site-1", None)]
+
+
+async def test_list_alerts_transmits_the_severity_filter(
+    servi: Callable[[], FauxService], client: AsyncClient
+) -> None:
+    service = servi()
+
+    await client.get("/api/v1/alerts?severity=critical")
+
+    assert service.appels == [(None, "critical")]
+
+
+async def test_list_alerts_returns_422_for_an_unknown_severity(
+    servi: Callable[[], FauxService], client: AsyncClient
+) -> None:
+    servi()
+
+    response = await client.get("/api/v1/alerts?severity=invalide")
+
+    assert response.status_code == 422
+
+
+async def test_list_alerts_returns_an_empty_list_when_there_is_nothing(
+    lecteur_connecte: None, fake_session: Callable[..., None], client: AsyncClient
+) -> None:
+    fake_session(result=[])
+
+    response = await client.get("/api/v1/alerts")
+
+    assert response.status_code == 200
+    assert response.json() == []

apps/backend/tests/api/test_openapi.py

@@ -22,6 +22,18 @@ ORIGINE_VERIFIEE = {
     ("POST", "/api/v1/auth/password"),
 }
 
+# Toute route derrière `require_role` (LecteurDep, OperateurDep, AdminDep) peut rendre 403 pour
+# `password_change_required`, pas seulement les routes `admin`.
+ROUTES_A_ROLE = {
+    ("GET", "/api/v1/users"),
+    ("POST", "/api/v1/users"),
+    ("PATCH", "/api/v1/users/{id}"),
+    ("POST", "/api/v1/users/{id}/password-reset"),
+    ("GET", "/api/v1/sites"),
+    ("GET", "/api/v1/sites/{site_id}"),
+    ("GET", "/api/v1/alerts"),
+}
+
 
 @pytest.fixture(scope="module")
 def schema() -> dict[str, Any]:
@@ -55,11 +67,11 @@ def test_every_route_demanding_an_identity_says_how_it_refuses(schema: dict[str,
     assert muettes == []
 
 
-def test_every_administration_route_documents_the_role_refusal(schema: dict[str, Any]) -> None:
+def test_every_role_guarded_route_documents_the_role_refusal(schema: dict[str, Any]) -> None:
     sans_403 = [
         (methode, chemin)
         for methode, chemin, operation in operations(schema)
-        if "users" in operation.get("tags", []) and "403" not in operation["responses"]
+        if (methode, chemin) in ROUTES_A_ROLE and "403" not in operation["responses"]
     ]
 
     assert sans_403 == []

apps/backend/tests/repositories/test_alert.py

@@ -0,0 +1,90 @@
+import uuid
+from datetime import UTC, datetime
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.energy import Alert
+from app.repositories.alert import AlertRepository
+from tests.repositories.test_site import creer as creer_site
+from tests.repositories.test_site import identifiant as identifiant_site
+
+pytestmark = pytest.mark.integration
+
+
+async def creer_alerte(session: AsyncSession, *, site_id: str, **overrides: object) -> Alert:
+    alerte = Alert(
+        source_alert_id=overrides.get("source_alert_id", f"ALR-{uuid.uuid4().hex[:12]}"),
+        site_id=site_id,
+        source=overrides.get("source", "enervision"),
+        timestamp=overrides.get("timestamp", datetime(2026, 9, 16, tzinfo=UTC)),
+        type=overrides.get("type", "threshold"),
+        severity=overrides.get("severity", "high"),
+        message=overrides.get("message", "Dépassement du seuil configuré"),
+        value=overrides.get("value", 812.5),
+        threshold=overrides.get("threshold", 720.0),
+        metric=overrides.get("metric", "consumption_kw"),
+        prediction_id=overrides.get("prediction_id"),
+        raw_data=overrides.get("raw_data", {}),
+    )
+    session.add(alerte)
+    await session.flush()
+    return alerte
+
+
+async def test_list_all_returns_the_alerts_sorted_by_timestamp_descending(
+    session: AsyncSession,
+) -> None:
+    site = await creer_site(session)
+    depot = AlertRepository(session)
+    ancienne = await creer_alerte(
+        session, site_id=site.site_id, timestamp=datetime(2026, 9, 1, tzinfo=UTC)
+    )
+    recente = await creer_alerte(
+        session, site_id=site.site_id, timestamp=datetime(2026, 9, 15, tzinfo=UTC)
+    )
+
+    alertes = await depot.list_all()
+    identifiants = [
+        a.alert_id for a in alertes if a.alert_id in (ancienne.alert_id, recente.alert_id)
+    ]
+    await session.rollback()
+
+    assert identifiants == [recente.alert_id, ancienne.alert_id]
+
+
+async def test_list_all_filters_by_site_id(session: AsyncSession) -> None:
+    premier = await creer_site(session)
+    second = await creer_site(session)
+    depot = AlertRepository(session)
+    voulue = await creer_alerte(session, site_id=premier.site_id)
+    await creer_alerte(session, site_id=second.site_id)
+
+    alertes = await depot.list_all(site_id=premier.site_id)
+    identifiants = [a.alert_id for a in alertes]
+    await session.rollback()
+
+    assert identifiants == [voulue.alert_id]
+
+
+async def test_list_all_filters_by_severity(session: AsyncSession) -> None:
+    site = await creer_site(session)
+    depot = AlertRepository(session)
+    voulue = await creer_alerte(session, site_id=site.site_id, severity="critical")
+    await creer_alerte(session, site_id=site.site_id, severity="low")
+
+    alertes = await depot.list_all(severity="critical")
+    identifiants = [a.alert_id for a in alertes]
+    await session.rollback()
+
+    assert identifiants == [voulue.alert_id]
+
+
+async def test_list_all_returns_an_empty_list_when_there_is_nothing(
+    session: AsyncSession,
+) -> None:
+    depot = AlertRepository(session)
+
+    alertes = await depot.list_all(site_id=identifiant_site())
+
+    assert list(alertes) == []

apps/backend/tests/services/test_alert.py

@@ -0,0 +1,55 @@
+from datetime import UTC, datetime
+
+from app.models.energy import Alert
+from app.services.alert import AlertService
+
+
+def alert(
+    alert_id: int = 1,
+    site_id: str = "site-1",
+    severity: str = "high",
+) -> Alert:
+    return Alert(
+        alert_id=alert_id,
+        source_alert_id=f"ALR-{alert_id}",
+        site_id=site_id,
+        source="enervision",
+        timestamp=datetime(2026, 9, 16, tzinfo=UTC),
+        type="threshold",
+        severity=severity,
+        message="Dépassement du seuil configuré",
+        value=812.5,
+        threshold=720.0,
+        metric="consumption_kw",
+        prediction_id=None,
+        raw_data={},
+    )
+
+
+class FakeRepository:
+    def __init__(self, alerts: list[Alert]) -> None:
+        self._alerts = alerts
+        self.appels: list[tuple[str | None, str | None]] = []
+
+    async def list_all(
+        self, *, site_id: str | None = None, severity: str | None = None
+    ) -> list[Alert]:
+        self.appels.append((site_id, severity))
+        return self._alerts
+
+
+async def test_list_all_returns_the_repository_alerts() -> None:
+    service = AlertService(alerts=FakeRepository([alert(1), alert(2)]))
+
+    alertes = await service.list_all()
+
+    assert [a.alert_id for a in alertes] == [1, 2]
+
+
+async def test_list_all_relays_the_filters_to_the_repository() -> None:
+    depot = FakeRepository([])
+    service = AlertService(alerts=depot)
+
+    await service.list_all(site_id="site-1", severity="critical")
+
+    assert depot.appels == [("site-1", "critical")]