M34: enforce domain integrity in PostgreSQL

backend/app/models/audit.py

@@ -1,7 +1,7 @@
 import uuid
 from datetime import datetime
 
-from sqlalchemy import DateTime, String
+from sqlalchemy import CheckConstraint, DateTime, Index, String
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import Mapped, mapped_column
 
@@ -13,6 +13,11 @@ ACTOR_TYPES = ("user", "service", "system")
 
 class AuditEvent(UUIDPrimaryKeyMixin, Base):
     __tablename__ = "audit_events"
+    __table_args__ = (
+        CheckConstraint("actor_type IN ('user','service','system')", name="ck_audit_actor_type"),
+        Index("ix_audit_action_occurred", "action", "occurred_at"),
+        Index("ix_audit_entity", "entity_type", "entity_id"),
+    )
 
     actor_type: Mapped[str] = mapped_column(String(20), nullable=False)
     actor_id: Mapped[uuid.UUID | None] = mapped_column(UUID(as_uuid=True))

backend/app/models/booking.py

@@ -1,7 +1,7 @@
 import uuid
 from datetime import datetime
 
-from sqlalchemy import Boolean, DateTime, ForeignKey, Integer, String
+from sqlalchemy import Boolean, CheckConstraint, DateTime, ForeignKey, Index, Integer, String
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import Mapped, mapped_column
 
@@ -13,6 +13,22 @@ BOOKING_STATUSES = ("reserved", "active", "returned", "cancelled", "blocked")
 
 class Booking(UUIDPrimaryKeyMixin, TimestampMixin, Base):
     __tablename__ = "bookings"
+    __table_args__ = (
+        CheckConstraint(
+            "status IN ('reserved','active','returned','cancelled','blocked')",
+            name="ck_bookings_status",
+        ),
+        CheckConstraint("ends_at > starts_at", name="ck_bookings_time_window"),
+        CheckConstraint(
+            "start_odometer_km IS NULL OR start_odometer_km >= 0",
+            name="ck_bookings_start_odometer",
+        ),
+        CheckConstraint(
+            "end_odometer_km IS NULL OR end_odometer_km >= 0",
+            name="ck_bookings_end_odometer",
+        ),
+        Index("ix_bookings_vehicle_status_window", "vehicle_id", "status", "starts_at", "ends_at"),
+    )
 
     public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
     customer_id: Mapped[uuid.UUID] = mapped_column(

backend/app/models/data_quality.py

@@ -2,7 +2,7 @@ import uuid
 from datetime import datetime
 from typing import TYPE_CHECKING
 
-from sqlalchemy import DateTime, ForeignKey, String
+from sqlalchemy import CheckConstraint, DateTime, ForeignKey, Index, String
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
@@ -25,6 +25,19 @@ ISSUE_STATUSES = ("open", "deferred", "resolved", "rejected")
 
 class DataQualityIssue(UUIDPrimaryKeyMixin, TimestampMixin, Base):
     __tablename__ = "data_quality_issues"
+    __table_args__ = (
+        CheckConstraint(
+            "rule_type IN ('possible_duplicate_customer','missing_required_field',"
+            "'odometer_regression','booking_overlap','vehicle_status_conflict')",
+            name="ck_data_quality_rule_type",
+        ),
+        CheckConstraint("severity IN ('low','medium','high')", name="ck_data_quality_severity"),
+        CheckConstraint(
+            "status IN ('open','deferred','resolved','rejected')",
+            name="ck_data_quality_status",
+        ),
+        Index("ix_data_quality_work_queue", "status", "due_at", "severity"),
+    )
 
     public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
     rule_type: Mapped[str] = mapped_column(String(40), nullable=False)

backend/app/models/outbox.py

@@ -1,7 +1,7 @@
 import uuid
 from datetime import datetime
 
-from sqlalchemy import DateTime, Integer, String, Text
+from sqlalchemy import CheckConstraint, DateTime, Index, Integer, String, Text
 from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import Mapped, mapped_column
 
@@ -32,6 +32,14 @@ def is_demo_scenario_failure(event: "OutboxEvent") -> bool:
 
 class OutboxEvent(TimestampMixin, Base):
     __tablename__ = "outbox_events"
+    __table_args__ = (
+        CheckConstraint(
+            "delivery_status IN ('pending','delivering','succeeded','failed')",
+            name="ck_outbox_delivery_status",
+        ),
+        CheckConstraint("attempts >= 0", name="ck_outbox_attempts"),
+        Index("ix_outbox_delivery_next_attempt", "delivery_status", "next_attempt_at"),
+    )
 
     event_id: Mapped[uuid.UUID] = mapped_column(
         UUID(as_uuid=True), primary_key=True, default=uuid.uuid4

backend/app/models/vehicle.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Boolean, Integer, String
+from sqlalchemy import Boolean, CheckConstraint, Integer, String
 from sqlalchemy.orm import Mapped, mapped_column
 
 from app.core.db import Base
@@ -9,6 +9,16 @@ OPERATIONAL_STATUSES = ("available", "rented", "cleaning", "maintenance", "block
 
 class Vehicle(UUIDPrimaryKeyMixin, TimestampMixin, Base):
     __tablename__ = "vehicles"
+    __table_args__ = (
+        CheckConstraint(
+            "operational_status IN ('available','rented','cleaning','maintenance','blocked')",
+            name="ck_vehicles_operational_status",
+        ),
+        CheckConstraint("model_year BETWEEN 1900 AND 2100", name="ck_vehicles_model_year"),
+        CheckConstraint("odometer_km >= 0", name="ck_vehicles_odometer"),
+        CheckConstraint("next_service_km >= 0", name="ck_vehicles_next_service"),
+        CheckConstraint("version >= 1", name="ck_vehicles_version"),
+    )
 
     public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
     make: Mapped[str] = mapped_column(String(80), nullable=False)