M54: harden operations and demo resilience

backend/app/api/routers/bookings.py

@@ -30,6 +30,7 @@ from app.schemas import (
     ReturnPreviewResult,
 )
 from app.services.audit import record_audit_event
+from app.services.data_quality import open_odometer_regression_issue
 from app.services.returns import preview_vehicle_return, register_vehicle_return
 
 router = APIRouter(prefix="/api/v1/bookings", tags=["bookings"])
@@ -146,8 +147,14 @@ def create_booking(
 ) -> BookingOut:
     if body.ends_at <= body.starts_at:
         raise HTTPException(status_code=422, detail="Booking end must be after its start")
-    customer = db.scalar(select(Customer).where(Customer.public_ref == body.customer_ref))
-    if customer is None or customer.merged_into_customer_id is not None:
+    customer = db.scalar(
+        select(Customer).where(Customer.public_ref == body.customer_ref).with_for_update()
+    )
+    if (
+        customer is None
+        or customer.merged_into_customer_id is not None
+        or customer.anonymized_at is not None
+    ):
         raise HTTPException(status_code=422, detail="Customer is unavailable for booking")
     # Serialise booking creation per vehicle. The overlap check must run after
     # acquiring this lock, otherwise two concurrent requests can both pass it.
@@ -179,7 +186,9 @@ def create_booking(
         status="reserved",
         start_odometer_km=None,
         end_odometer_km=None,
-        requirements_complete=body.requirements_complete,
+        # Requirements are intentionally confirmed in a separate, audited action.
+        # Never allow booking creation to bypass that operational checkpoint.
+        requirements_complete=False,
     )
     db.add(booking)
     db.flush()
@@ -225,6 +234,15 @@ def checkout_booking(
     if active_conflict is not None:
         raise HTTPException(status_code=409, detail="Vehicle already has an active booking")
 
+    correlation_id = uuid.uuid4()
+    before_booking = {
+        "status": booking.status,
+        "start_odometer_km": booking.start_odometer_km,
+    }
+    before_vehicle = {
+        "operational_status": vehicle.operational_status,
+        "odometer_km": vehicle.odometer_km,
+    }
     attention_reasons: list[str] = []
     if body.start_odometer_km < vehicle.odometer_km:
         attention_reasons.append("odometer_regression")
@@ -250,6 +268,18 @@ def checkout_booking(
         completed_by=user.display_name,
     )
     db.add(inspection)
+    if "odometer_regression" in attention_reasons:
+        open_odometer_regression_issue(
+            db,
+            vehicle=vehicle,
+            reading_ref=inspection.public_ref,
+            reading_km=body.start_odometer_km,
+            canonical_km=vehicle.odometer_km,
+            source_type="checkout",
+            related_refs=[booking.public_ref, inspection.public_ref],
+            actor_label=user.display_name,
+            correlation_id=correlation_id,
+        )
     if attention_reasons:
         booking.status = "blocked"
         vehicle.operational_status = (
@@ -269,13 +299,31 @@ def checkout_booking(
         action="booking_checkout_recorded",
         entity_type="booking",
         entity_id=booking.id,
+        correlation_id=correlation_id,
+        before=before_booking,
         after={
             "inspection_ref": inspection.public_ref,
             "booking_status": booking.status,
+            "start_odometer_km": booking.start_odometer_km,
             "vehicle_status": vehicle.operational_status,
             "attention_reasons": attention_reasons,
         },
     )
+    record_audit_event(
+        db,
+        actor_type="user",
+        actor_label=user.display_name,
+        action="vehicle_status_changed",
+        entity_type="vehicle",
+        entity_id=vehicle.id,
+        correlation_id=correlation_id,
+        before=before_vehicle,
+        after={
+            "operational_status": vehicle.operational_status,
+            "odometer_km": vehicle.odometer_km,
+        },
+        metadata={"booking_ref": booking.public_ref, "inspection_ref": inspection.public_ref},
+    )
     db.commit()
     return CheckoutBookingResult(
         booking_ref=booking.public_ref,

backend/app/api/routers/customers.py

@@ -21,6 +21,7 @@ def search_customers(
         select(Customer)
         .where(
             Customer.merged_into_customer_id.is_(None),
+            Customer.anonymized_at.is_(None),
             or_(
                 Customer.public_ref.ilike(term),
                 Customer.first_name.ilike(term),

backend/app/api/routers/data_quality.py

@@ -11,6 +11,7 @@ from app.models.booking import Booking
 from app.models.customer import Customer
 from app.models.data_quality import DataQualityIssue
 from app.models.inspection import Inspection
+from app.models.maintenance import MaintenanceRecord
 from app.models.user import User
 from app.models.vehicle import Vehicle
 from app.schemas import (
@@ -224,6 +225,8 @@ _PREFIX_TO_TYPE = {
     "MO-": "vehicle",
     "BK-": "booking",
     "INSP-": "inspection",
+    "MAINT-": "maintenance",
+    "MNT-": "maintenance",
 }
 
 
@@ -292,6 +295,17 @@ def _snapshot(entity_type: str, ref: str, db: Session) -> dict | None:
             "completed_at": inspection.completed_at.isoformat(),
             "booking_ref": booking.public_ref if booking else None,
         }
+    if entity_type == "maintenance":
+        record = db.scalar(select(MaintenanceRecord).where(MaintenanceRecord.public_ref == ref))
+        if record is None:
+            return None
+        return {
+            "entity_type": "maintenance",
+            "public_ref": record.public_ref,
+            "odometer_km": record.odometer_km,
+            "occurred_at": record.occurred_at.isoformat(),
+            "category": record.category,
+        }
     return None
 
 

backend/app/api/routers/demo.py

@@ -3,6 +3,7 @@ from __future__ import annotations
 import threading
 import time
 import uuid
+from datetime import UTC, datetime
 
 from fastapi import APIRouter, Depends, HTTPException, Request, Response, status
 from sqlalchemy import func, select
@@ -10,7 +11,9 @@ from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_user, get_db, require_operations_manager
 from app.core.config import get_settings
+from app.core.db import begin_exclusive_demo_reset, end_exclusive_demo_reset, engine
 from app.core.security import SessionPayload, create_session_token, read_session_token
+from app.models.audit import AuditEvent
 from app.models.user import User
 from app.schemas import CurrentUser, DemoLoginRequest, DemoManifestOut
 from app.seed_loader import reset_and_seed
@@ -21,7 +24,6 @@ from app.services.sessions import revoke_session
 router = APIRouter(prefix="/api/v1/demo", tags=["demo"])
 settings = get_settings()
 _reset_guard = threading.Lock()
-_last_reset_monotonic = 0.0
 _RESET_ADVISORY_LOCK_ID = 706_533_149
 
 
@@ -110,7 +112,6 @@ def demo_reset(
     db: Session = Depends(get_db),
     user: CurrentUser = Depends(require_operations_manager),
 ) -> dict:
-    global _last_reset_monotonic
     if not settings.mobilityops_demo_mode:
         # Outside demo mode the reset endpoint must not exist at all: it wipes
         # operational data and replaces it with synthetic records.
@@ -122,19 +123,35 @@ def demo_reset(
         )
     if not _reset_guard.acquire(blocking=False):
         raise HTTPException(status_code=409, detail="A demo reset is already running.")
+    replica_lock_connection = None
     try:
-        elapsed = time.monotonic() - _last_reset_monotonic
-        if _last_reset_monotonic and elapsed < settings.demo_reset_cooldown_seconds:
+        # A session-level lock on its own connection rejects another replica immediately;
+        # the main DB session can then safely end its auth read transaction and wait on
+        # the normal shared/exclusive data barrier without releasing this replica guard.
+        replica_lock_connection = engine.connect()
+        locked = replica_lock_connection.scalar(
+            select(func.pg_try_advisory_lock(_RESET_ADVISORY_LOCK_ID))
+        )
+        if not locked:
+            raise HTTPException(status_code=409, detail="A demo reset is already running.")
+        begin_exclusive_demo_reset(db)
+        # The audit timestamp is shared by every replica. A process-local monotonic
+        # timestamp cannot protect a multi-replica deployment.
+        last_reset_at = db.scalar(
+            select(AuditEvent.occurred_at)
+            .where(AuditEvent.action == "demo_reset")
+            .order_by(AuditEvent.occurred_at.desc())
+            .limit(1)
+        )
+        elapsed = (datetime.now(UTC) - last_reset_at).total_seconds() if last_reset_at else None
+        if elapsed is not None and elapsed < settings.demo_reset_cooldown_seconds:
             retry_after = max(1, int(settings.demo_reset_cooldown_seconds - elapsed + 0.999))
             raise HTTPException(
                 status_code=429,
                 detail=f"Demo reset is cooling down. Retry in {retry_after} seconds.",
                 headers={"Retry-After": str(retry_after)},
             )
-        locked = db.scalar(select(func.pg_try_advisory_xact_lock(_RESET_ADVISORY_LOCK_ID)))
-        if not locked:
-            raise HTTPException(status_code=409, detail="A demo reset is already running.")
-        result = reset_and_seed(db, preserve_integration_telemetry=True)
+        result = reset_and_seed(db, preserve_integration_telemetry=True, commit=False)
         integrity = scenario_integrity_report(db)
         record_audit_event(
             db,
@@ -149,8 +166,15 @@ def demo_reset(
             },
         )
         db.commit()
-        _last_reset_monotonic = time.monotonic()
+        end_exclusive_demo_reset(db)
     finally:
+        if replica_lock_connection is not None:
+            try:
+                replica_lock_connection.scalar(
+                    select(func.pg_advisory_unlock(_RESET_ADVISORY_LOCK_ID))
+                )
+            finally:
+                replica_lock_connection.close()
         _reset_guard.release()
     response.delete_cookie(settings.session_cookie_name)
     return {

backend/app/api/routers/integrations.py

@@ -1,12 +1,13 @@
 from __future__ import annotations
 
+import hashlib
 import hmac
 import uuid
 from datetime import UTC, datetime
 from pathlib import Path
 
 from fastapi import APIRouter, Depends, Header
-from sqlalchemy import select
+from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
 from app.api.deps import get_db
@@ -51,6 +52,13 @@ def _require_service_token(service_token: str) -> None:
         raise AppError("UNAUTHORIZED_SERVICE", "Invalid service token.", status_code=401)
 
 
+def _lock_idempotency_key(db: Session, namespace: str, key: str) -> None:
+    """Serialize callback check+insert by a stable, transaction-scoped key."""
+    digest = hashlib.sha256(f"{namespace}:{key}".encode()).digest()
+    lock_id = int.from_bytes(digest[:8], byteorder="big", signed=True)
+    db.scalar(select(func.pg_advisory_xact_lock(lock_id)))
+
+
 @router.post("/heartbeat", response_model=N8nHeartbeatResult)
 def workflow_heartbeat(
     body: N8nHeartbeatIn,
@@ -61,6 +69,7 @@ def workflow_heartbeat(
     _require_service_token(service_token)
     if body.workflow_name not in _CANONICAL_WORKFLOW_NAMES:
         raise AppError("UNKNOWN_WORKFLOW", "Unknown Fleet Ops workflow.", status_code=422)
+    _lock_idempotency_key(db, "n8n_workflow_heartbeat", f"{body.execution_id}:{body.status}")
     already_recorded = (
         db.scalar(
             select(AuditEvent.id).where(
@@ -109,9 +118,29 @@ def return_callback(
             "INVALID_IDEMPOTENCY_KEY", "Idempotency-Key must be the event's UUID.", status_code=422
         ) from exc
 
-    event = db.scalar(select(OutboxEvent).where(OutboxEvent.event_id == event_id))
+    event = db.scalar(select(OutboxEvent).where(OutboxEvent.event_id == event_id).with_for_update())
     if event is None:
         raise AppError("EVENT_NOT_FOUND", "No outbox event matches this event ID.", status_code=404)
+    if body.event_id != event_id:
+        raise AppError(
+            "CALLBACK_EVENT_MISMATCH",
+            "Callback event_id does not match Idempotency-Key.",
+            status_code=409,
+        )
+    try:
+        expected_correlation_id = uuid.UUID(str(event.payload_json["correlation_id"]))
+    except (KeyError, TypeError, ValueError) as exc:
+        raise AppError(
+            "INVALID_EVENT_CORRELATION",
+            "The stored outbox event has no valid correlation ID.",
+            status_code=409,
+        ) from exc
+    if body.correlation_id != expected_correlation_id:
+        raise AppError(
+            "CALLBACK_CORRELATION_MISMATCH",
+            "Callback correlation_id does not match the outbox event.",
+            status_code=409,
+        )
 
     # Idempotent by event ID: n8n or our own dispatcher may redeliver the same event
     # (e.g. a lost response after a timeout), so this callback must not double-record.
@@ -131,7 +160,7 @@ def return_callback(
             actor_label="n8n",
             action="n8n_return_followup_recorded",
             entity_type="booking",
-            correlation_id=body.correlation_id,
+            correlation_id=expected_correlation_id,
             after={"follow_up": body.follow_up, "summary": body.summary},
             metadata={"event_id": str(event_id)},
         )
@@ -170,6 +199,7 @@ def workflow_error(
     other Fleet Ops n8n workflow. Idempotent on execution_id: n8n may redeliver the same
     error report (e.g. after a timed-out response), so this must not double-record."""
     _require_service_token(service_token)
+    _lock_idempotency_key(db, "n8n_workflow_failure", body.execution_id)
 
     already_recorded = (
         db.scalar(
@@ -181,19 +211,13 @@ def workflow_error(
         is not None
     )
     if not already_recorded:
-        correlation_id: uuid.UUID | None = None
-        if body.correlation_id:
-            try:
-                correlation_id = uuid.UUID(body.correlation_id)
-            except ValueError:
-                correlation_id = None
         record_audit_event(
             db,
             actor_type="service",
             actor_label="n8n error handler",
             action="n8n_workflow_failure_registered",
             entity_type="automation",
-            correlation_id=correlation_id,
+            correlation_id=body.correlation_id,
             after={
                 "workflow_id": body.workflow_id,
                 "workflow_name": body.workflow_name,
@@ -248,6 +272,7 @@ def procedures_sync_result(
     RAGcore Procedure Sync" workflow once it finishes uploading procedures to RAGcore.
     Idempotent on execution_id, matching the workflow-error and return-callback pattern."""
     _require_service_token(service_token)
+    _lock_idempotency_key(db, "n8n_procedure_sync", body.execution_id)
 
     already_recorded = (
         db.scalar(

backend/app/api/routers/knowledge.py

@@ -53,7 +53,9 @@ def ask_question(
         client_ip = (
             forwarded.split(",")[-1].strip()
             if forwarded
-            else request.client.host if request.client else "unknown"
+            else request.client.host
+            if request.client
+            else "unknown"
         )
         token = request.cookies.get(settings.session_cookie_name, "")
         session_key = hashlib.sha256(token.encode("utf-8")).hexdigest()

backend/app/api/routers/vehicles.py

@@ -27,6 +27,7 @@ from app.schemas import (
     VehiclePageOut,
 )
 from app.services.audit import record_audit_event
+from app.services.data_quality import open_odometer_regression_issue
 
 router = APIRouter(prefix="/api/v1/vehicles", tags=["vehicles"])
 
@@ -143,7 +144,7 @@ def list_vehicles(
 def get_vehicle(
     public_ref: str,
     db: Session = Depends(get_db),
-    _user: CurrentUser = Depends(get_current_user),
+    user: CurrentUser = Depends(get_current_user),
 ) -> VehicleDetailOut:
     vehicle = db.scalar(select(Vehicle).where(Vehicle.public_ref == public_ref))
     if vehicle is None:
@@ -163,11 +164,21 @@ def get_vehicle(
         .where(MaintenanceRecord.vehicle_id == vehicle.id)
         .order_by(MaintenanceRecord.occurred_at.desc())
     ).all()
-    issues = db.scalars(
-        select(DataQualityIssue)
-        .where(DataQualityIssue.entity_type == "vehicle", DataQualityIssue.entity_id == vehicle.id)
-        .order_by(DataQualityIssue.detected_at.desc())
-    ).all()
+    # Detailed data-quality evidence is an operations-manager surface. Employees still
+    # get the operational vehicle record they need, but never receive hidden evidence in
+    # the payload merely because the frontend omits the Quality tab.
+    issues = (
+        db.scalars(
+            select(DataQualityIssue)
+            .where(
+                DataQualityIssue.entity_type == "vehicle",
+                DataQualityIssue.entity_id == vehicle.id,
+            )
+            .order_by(DataQualityIssue.detected_at.desc())
+        ).all()
+        if user.role == "operations_manager"
+        else []
+    )
 
     booking_by_id = {b.id: b.public_ref for b in bookings}
     next_booking = next(
@@ -276,6 +287,12 @@ def create_maintenance_record(
     vehicle = db.scalar(select(Vehicle).where(Vehicle.public_ref == public_ref).with_for_update())
     if vehicle is None:
         raise HTTPException(status_code=404, detail="Vehicle not found")
+    correlation_id = uuid.uuid4()
+    before_vehicle = {
+        "operational_status": vehicle.operational_status,
+        "odometer_km": vehicle.odometer_km,
+        "next_service_km": vehicle.next_service_km,
+    }
     record = MaintenanceRecord(
         public_ref=f"MAINT-{uuid.uuid4().hex[:8].upper()}",
         vehicle_id=vehicle.id,
@@ -285,6 +302,17 @@ def create_maintenance_record(
         summary=body.summary.strip(),
     )
     db.add(record)
+    open_odometer_regression_issue(
+        db,
+        vehicle=vehicle,
+        reading_ref=record.public_ref,
+        reading_km=body.odometer_km,
+        canonical_km=vehicle.odometer_km,
+        source_type="maintenance",
+        related_refs=[record.public_ref],
+        actor_label=user.display_name,
+        correlation_id=correlation_id,
+    )
     vehicle.odometer_km = max(vehicle.odometer_km, body.odometer_km)
     if body.next_service_km is not None:
         if body.next_service_km < vehicle.odometer_km:
@@ -301,7 +329,14 @@ def create_maintenance_record(
         action="maintenance_record_created",
         entity_type="vehicle",
         entity_id=vehicle.id,
-        after={"maintenance_ref": record.public_ref, "status": vehicle.operational_status},
+        correlation_id=correlation_id,
+        before=before_vehicle,
+        after={
+            "maintenance_ref": record.public_ref,
+            "operational_status": vehicle.operational_status,
+            "odometer_km": vehicle.odometer_km,
+            "next_service_km": vehicle.next_service_km,
+        },
     )
     db.commit()
     return MaintenanceOut(

backend/app/core/config.py

@@ -33,7 +33,11 @@ class Settings(BaseSettings):
     n8n_callback_token: str = "replace-me-n8n-callback-token"
     n8n_dispatch_enabled: bool = True
     n8n_dispatch_interval_seconds: float = 3.0
-    n8n_http_timeout_seconds: float = 5.0
+    # The synchronous n8n workflow performs two bounded, retried callbacks before it
+    # acknowledges an event. Keep this above that complete workflow budget, while the
+    # delivery lease remains the wider crash-recovery boundary (enforced by the contract
+    # check in scripts/check-contracts.py).
+    n8n_http_timeout_seconds: float = 15.0
     n8n_max_attempts: int = 5
     n8n_delivery_lease_seconds: float = 120.0
     app_secret: str = "replace-in-production"

backend/app/core/db.py

@@ -1,6 +1,6 @@
 from collections.abc import Generator
 
-from sqlalchemy import create_engine
+from sqlalchemy import create_engine, event, func, select
 from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
 
 from app.core.config import get_settings
@@ -10,6 +10,37 @@ settings = get_settings()
 engine = create_engine(settings.database_url, pool_pre_ping=True, future=True)
 SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, future=True)
 
+# Every SQLAlchemy transaction participates in a shared database-wide barrier. Normal
+# reads/writes coexist; the short demo reset takes the exclusive form so it can never
+# interleave deletes/inserts with an API request, scanner, callback, or dispatcher cycle.
+DEMO_DATA_BARRIER_LOCK_ID = 5_344_725_149_212_793_901
+_EXCLUSIVE_RESET_INFO_KEY = "mobilityops_demo_reset_exclusive"
+
+
+@event.listens_for(Session, "after_begin")
+def _acquire_demo_data_barrier(session: Session, _transaction, connection) -> None:
+    if connection.dialect.name != "postgresql":
+        return
+    lock = (
+        func.pg_advisory_xact_lock(DEMO_DATA_BARRIER_LOCK_ID)
+        if session.info.get(_EXCLUSIVE_RESET_INFO_KEY)
+        else func.pg_advisory_xact_lock_shared(DEMO_DATA_BARRIER_LOCK_ID)
+    )
+    connection.execute(select(lock))
+
+
+def begin_exclusive_demo_reset(db: Session) -> None:
+    """Make the session's next transaction the exclusive side of the reset barrier."""
+    if db.in_transaction():
+        # Auth normally already read the user under a shared barrier. End that read-only
+        # transaction before requesting exclusive; in-place lock upgrades can deadlock.
+        db.rollback()
+    db.info[_EXCLUSIVE_RESET_INFO_KEY] = True
+
+
+def end_exclusive_demo_reset(db: Session) -> None:
+    db.info.pop(_EXCLUSIVE_RESET_INFO_KEY, None)
+
 
 class Base(DeclarativeBase):
     pass

backend/app/schemas.py

@@ -4,9 +4,13 @@ import uuid
 from datetime import datetime
 from typing import Annotated, Any, Literal
 
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, StringConstraints
 
 Role = Literal["operations_manager", "rental_employee"]
+NonBlankOperationalReason = Annotated[
+    str,
+    StringConstraints(strip_whitespace=True, min_length=3, max_length=500),
+]
 
 
 class DemoLoginRequest(BaseModel):
@@ -93,17 +97,16 @@ class CreateBookingRequest(BaseModel):
     vehicle_ref: str = Field(min_length=3, max_length=20)
     starts_at: datetime
     ends_at: datetime
-    requirements_complete: bool = False
 
 
 class CompleteBookingRequirementsRequest(BaseModel):
-    confirmation: str = Field(min_length=3, max_length=500)
+    confirmation: NonBlankOperationalReason
 
 
 class RescheduleBookingRequest(BaseModel):
     starts_at: datetime
     ends_at: datetime
-    reason: str = Field(min_length=3, max_length=500)
+    reason: NonBlankOperationalReason
 
 
 class CustomerOptionOut(BaseModel):
@@ -122,7 +125,7 @@ class AvailableVehicleOut(BaseModel):
 
 
 class CancelBookingRequest(BaseModel):
-    reason: str = Field(min_length=3, max_length=500)
+    reason: NonBlankOperationalReason
 
 
 class CheckoutBookingRequest(BaseModel):
@@ -225,7 +228,7 @@ class CreateMaintenanceRequest(BaseModel):
 
 
 class ReleaseVehicleRequest(BaseModel):
-    reason: str = Field(min_length=3, max_length=500)
+    reason: NonBlankOperationalReason
 
 
 class DataQualityIssueOut(BaseModel):
@@ -295,7 +298,7 @@ class WorkflowErrorReportIn(BaseModel):
     ]
     error_summary: str = Field(max_length=500)
     trigger_context: str | None = Field(default=None, max_length=200)
-    correlation_id: str | None = None
+    correlation_id: uuid.UUID | None = None
     attempt: int = Field(default=1, ge=1, le=1000)
     retry_action: str | None = Field(default=None, max_length=200)
 
@@ -433,7 +436,8 @@ class ReturnCallbackIn(BaseModel):
 
     model_config = ConfigDict(extra="ignore")
 
-    correlation_id: uuid.UUID | None = None
+    event_id: uuid.UUID
+    correlation_id: uuid.UUID
     follow_up: str | None = Field(default=None, max_length=200)
     summary: str | None = Field(default=None, max_length=2000)
 

backend/app/seed_loader.py

@@ -11,6 +11,7 @@ from sqlalchemy import delete, insert, update
 from sqlalchemy.orm import Session
 
 from app.core.config import get_settings
+from app.core.db import begin_exclusive_demo_reset, end_exclusive_demo_reset
 from app.models.audit import AuditEvent
 from app.models.booking import Booking
 from app.models.customer import Customer
@@ -201,7 +202,11 @@ def load_seed(db: Session) -> SeedResult:
     counts["bookings"] = len(booking_rows)
 
     inspection_rows = []
-    for row in _read_csv("inspections.csv"):
+    inspection_source_rows = _read_csv("inspections.csv")
+    return_inspection_row_by_booking_ref = {
+        row["booking_ref"]: row for row in inspection_source_rows if row["type"] == "return"
+    }
+    for row in inspection_source_rows:
         inspection_rows.append(
             {
                 "id": uuid.uuid4(),
@@ -259,16 +264,18 @@ def load_seed(db: Session) -> SeedResult:
         }
 
     def _odometer_regression_signal(later_ref: str, earlier_ref: str) -> list[dict]:
-        later = booking_row_by_ref[later_ref]
-        earlier = booking_row_by_ref[earlier_ref]
+        later = return_inspection_row_by_booking_ref[later_ref]
+        earlier = return_inspection_row_by_booking_ref[earlier_ref]
         return [
             {
                 "code": "odometer.regression",
+                "source_type": "return",
                 "params": {
-                    "later_ref": later_ref,
-                    "later_km": later["end_odometer_km"],
-                    "earlier_ref": earlier_ref,
-                    "earlier_km": earlier["end_odometer_km"],
+                    "later_ref": later["public_ref"],
+                    "later_km": int(later["odometer_km"]),
+                    "earlier_ref": earlier["public_ref"],
+                    "earlier_km": int(earlier["odometer_km"]),
+                    "booking_ref": later_ref,
                 },
             }
         ]
@@ -354,6 +361,27 @@ def load_seed(db: Session) -> SeedResult:
         entity_type, entity_id = resolve_entity(row["entity_ref"])
         related_ref = row.get("related_ref") or ""
         related_refs = related_ref.split("|") if related_ref else []
+        signals = _seed_signals(row["public_ref"], row["entity_ref"], related_refs)
+        evidence_extra: dict[str, object] = {}
+        if row["rule_type"] == "odometer_regression" and signals:
+            params = signals[0].get("params", {})
+            later_ref = params.get("later_ref")
+            earlier_ref = params.get("earlier_ref")
+            booking_ref = params.get("booking_ref")
+            if (
+                isinstance(earlier_ref, str)
+                and isinstance(later_ref, str)
+                and isinstance(booking_ref, str)
+            ):
+                # The authored CSV prose predates structured references. Preserve the
+                # two real source bookings so the detail page can show evidence, while
+                # only the later (regressing) reading is eligible for correction.
+                related_refs = [earlier_ref, booking_ref, later_ref]
+                evidence_extra = {
+                    "source_type": signals[0].get("source_type", "return"),
+                    "source_types": [signals[0].get("source_type", "return")],
+                    "correctable_booking_refs": [booking_ref],
+                }
         severity_due_delta = {
             "high": timedelta(hours=4),
             "medium": timedelta(days=1),
@@ -372,7 +400,8 @@ def load_seed(db: Session) -> SeedResult:
                     "summary": row["evidence"],
                     "entity_ref": row["entity_ref"],
                     "related_refs": related_refs,
-                    "signals": _seed_signals(row["public_ref"], row["entity_ref"], related_refs),
+                    "signals": signals,
+                    **evidence_extra,
                 },
                 "proposed_action_json": {},
                 "detected_at": now,
@@ -449,12 +478,23 @@ def load_seed(db: Session) -> SeedResult:
     return SeedResult(counts=counts, anchor_date=today, seeded_at=seeded_at)
 
 
-def reset_and_seed(db: Session, *, preserve_integration_telemetry: bool = False) -> SeedResult:
+def reset_and_seed(
+    db: Session,
+    *,
+    preserve_integration_telemetry: bool = False,
+    commit: bool = True,
+) -> SeedResult:
     from app.services.data_quality import run_scan
 
+    if not db.info.get("mobilityops_demo_reset_exclusive"):
+        begin_exclusive_demo_reset(db)
     clear_all(db, preserve_integration_telemetry=preserve_integration_telemetry)
     result = load_seed(db)
-    db.commit()
-    scan = run_scan(db)
+    scan = run_scan(db, commit=False)
     result.counts["data_quality_issues"] += sum(scan.created.values())
+    if commit:
+        db.commit()
+        end_exclusive_demo_reset(db)
+    else:
+        db.flush()
     return result

backend/app/services/data_quality.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 import uuid
 from dataclasses import dataclass, field
-from datetime import UTC, datetime, timedelta
+from datetime import UTC, datetime
 
 from sqlalchemy import func, select, update
 from sqlalchemy.orm import Session
@@ -11,10 +11,22 @@ from app.core.errors import AppError
 from app.models.booking import Booking
 from app.models.customer import Customer
 from app.models.data_quality import DataQualityIssue
+from app.models.inspection import Inspection
+from app.models.maintenance import MaintenanceRecord
 from app.models.vehicle import Vehicle
-from app.schemas import CurrentUser, ResolveOdometerRegressionRequest
+from app.schemas import CurrentUser
 from app.services.audit import record_audit_event
+from app.services.data_quality_common import has_open_issue as _has_open_issue
+from app.services.data_quality_common import issue_due_at
+from app.services.data_quality_common import load_open_issue as _load_open_issue
+from app.services.data_quality_common import new_scan_ref as _new_scan_ref
 from app.services.data_quality_duplicate_scan import scan_duplicate_customers
+from app.services.data_quality_odometer import (
+    open_odometer_regression_issue as open_odometer_regression_issue,
+)
+from app.services.data_quality_odometer import (
+    resolve_odometer_regression as resolve_odometer_regression,
+)
 from app.services.vehicle_status import (
     RECOMMENDATION_CODE_NO_CONFLICT,
     VehicleStatusRecommendation,
@@ -28,15 +40,6 @@ REQUIRED_VEHICLE_FIELDS = ("registration_number", "make", "model", "location")
 DATA_QUALITY_SCAN_LOCK_ID = 6_138_493_717_091_029_491
 
 
-def issue_due_at(detected_at: datetime, severity: str) -> datetime:
-    """Return the local operational SLA deadline for a newly detected issue."""
-    return detected_at + {
-        "high": timedelta(hours=4),
-        "medium": timedelta(days=1),
-        "low": timedelta(days=3),
-    }.get(severity, timedelta(days=1))
-
-
 @dataclass
 class ScanResult:
     created: dict[str, int] = field(default_factory=dict)
@@ -45,25 +48,6 @@ class ScanResult:
         self.created[rule_type] = self.created.get(rule_type, 0) + 1
 
 
-def _has_open_issue(db: Session, rule_type: str, entity_type: str, entity_id: uuid.UUID) -> bool:
-    return (
-        db.scalar(
-            select(DataQualityIssue.id).where(
-                DataQualityIssue.rule_type == rule_type,
-                DataQualityIssue.entity_type == entity_type,
-                DataQualityIssue.entity_id == entity_id,
-                DataQualityIssue.status == "open",
-            )
-        )
-        is not None
-    )
-
-
-def _new_scan_ref(prefix: str) -> str:
-    """Generate a stable human-readable prefix with a concurrent-safe suffix."""
-    return f"{prefix}-{uuid.uuid4().hex[:10].upper()}"
-
-
 def _open_issue(
     db: Session,
     scan: ScanResult,
@@ -76,6 +60,7 @@ def _open_issue(
     entity_ref: str,
     related_refs: list[str],
     signals: list[dict] | None = None,
+    evidence_extra: dict | None = None,
 ) -> None:
     if _has_open_issue(db, rule_type, entity_type, entity_id):
         return
@@ -103,6 +88,7 @@ def _open_issue(
         "related_refs": related_refs,
         "signals": signals or [],
     }
+    evidence.update(evidence_extra or {})
     if previous is not None:
         evidence["reopened_from"] = previous.public_ref
         evidence["previous_decision"] = previous.status
@@ -235,57 +221,110 @@ def _scan_vehicle_status_conflicts(db: Session, scan: ScanResult) -> None:
         )
 
 
-def _scan_odometer_regressions(db: Session, scan: ScanResult) -> None:
-    # The seed dataset's vehicle.odometer_km is generated independently of booking
-    # history, so comparing every historical booking against it produces near-universal
-    # false positives. Instead check the booking sequence's own internal consistency:
-    # each vehicle's completed bookings should show a non-decreasing odometer reading.
-    vehicles = {v.id: v for v in db.scalars(select(Vehicle)).all()}
-    bookings_by_vehicle: dict[uuid.UUID, list[Booking]] = {}
-    for booking in db.scalars(
+def _scan_odometer_regressions(
+    db: Session,
+    scan: ScanResult,
+    *,
+    actor_label: str | None,
+    actor_type: str,
+) -> None:
+    # Compare the chronological history with itself rather than every historical reading
+    # to today's canonical value. That detects imported checkout/return/maintenance
+    # regressions without flagging every legitimate older reading.
+    # Runtime checkout/return/maintenance mutations take the vehicle lock before they
+    # inspect or append DQ-03 evidence. Taking the same lock here makes scan-vs-command
+    # check/merge atomic and prevents a partial-unique race for the open issue.
+    vehicles = {
+        v.id: v for v in db.scalars(select(Vehicle).order_by(Vehicle.id).with_for_update()).all()
+    }
+    readings_by_vehicle: dict[uuid.UUID, list[tuple[datetime, str, int, str, str | None]]] = {}
+    inspections = db.scalars(select(Inspection)).all()
+    return_inspection_booking_ids = {
+        inspection.booking_id for inspection in inspections if inspection.type == "return"
+    }
+    returned_bookings = db.scalars(
         select(Booking).where(Booking.status == "returned", Booking.end_odometer_km.is_not(None))
-    ).all():
-        bookings_by_vehicle.setdefault(booking.vehicle_id, []).append(booking)
+    ).all()
+    booking_ref_by_id = {booking.id: booking.public_ref for booking in returned_bookings}
+    for booking in returned_bookings:
+        # A real return inspection owns the actual reading timestamp. Using the booking's
+        # planned ends_at as a duplicate second reading can make an early return appear to
+        # go backwards after a newer real inspection. Keep booking data only as the legacy
+        # import fallback when no return inspection exists.
+        if booking.id in return_inspection_booking_ids:
+            continue
+        assert booking.end_odometer_km is not None
+        readings_by_vehicle.setdefault(booking.vehicle_id, []).append(
+            (
+                booking.ends_at,
+                booking.public_ref,
+                booking.end_odometer_km,
+                "booking",
+                booking.public_ref,
+            )
+        )
+    for inspection in inspections:
+        readings_by_vehicle.setdefault(inspection.vehicle_id, []).append(
+            (
+                inspection.completed_at,
+                inspection.public_ref,
+                inspection.odometer_km,
+                inspection.type,
+                (
+                    booking_ref_by_id.get(inspection.booking_id)
+                    if inspection.type == "return"
+                    else None
+                ),
+            )
+        )
+    for record in db.scalars(select(MaintenanceRecord)).all():
+        readings_by_vehicle.setdefault(record.vehicle_id, []).append(
+            (record.occurred_at, record.public_ref, record.odometer_km, "maintenance", None)
+        )
 
-    for vehicle_id, bookings in bookings_by_vehicle.items():
-        bookings.sort(key=lambda b: b.ends_at)
-        for earlier, later in zip(bookings, bookings[1:], strict=False):
-            # The query above filters end_odometer_km IS NOT NULL, so both are ints here.
-            assert earlier.end_odometer_km is not None
-            assert later.end_odometer_km is not None
-            if later.end_odometer_km < earlier.end_odometer_km:
+    for vehicle_id, readings in readings_by_vehicle.items():
+        readings.sort(key=lambda reading: (reading[0], reading[1]))
+        highest = readings[0] if readings else None
+        for later in readings[1:]:
+            assert highest is not None
+            if later[2] < highest[2]:
                 vehicle = vehicles[vehicle_id]
-                _open_issue(
+                had_open_issue = _has_open_issue(
                     db,
-                    scan,
-                    rule_type="odometer_regression",
-                    entity_type="vehicle",
-                    entity_id=vehicle_id,
-                    severity="medium",
-                    summary=(
-                        f"Booking {later.public_ref} recorded {later.end_odometer_km} km, "
-                        f"below the {earlier.end_odometer_km} km recorded by earlier "
-                        f"booking {earlier.public_ref}."
-                    ),
-                    entity_ref=vehicle.public_ref,
-                    related_refs=[earlier.public_ref, later.public_ref],
-                    signals=[
-                        {
-                            "code": "odometer.regression",
-                            "params": {
-                                "later_ref": later.public_ref,
-                                "later_km": later.end_odometer_km,
-                                "earlier_ref": earlier.public_ref,
-                                "earlier_km": earlier.end_odometer_km,
-                            },
-                        }
-                    ],
+                    "odometer_regression",
+                    "vehicle",
+                    vehicle_id,
                 )
-                break
+                issue = open_odometer_regression_issue(
+                    db,
+                    vehicle=vehicle,
+                    reading_ref=later[1],
+                    reading_km=later[2],
+                    canonical_km=highest[2],
+                    canonical_ref=highest[1],
+                    source_type=later[3],
+                    related_refs=list(
+                        dict.fromkeys(
+                            [highest[1], later[1], *([later[4]] if later[4] is not None else [])]
+                        )
+                    ),
+                    correctable_booking_refs=[later[4]] if later[4] is not None else [],
+                    public_ref=_new_scan_ref("DQ-SCAN"),
+                    actor_label=actor_label,
+                    actor_type=actor_type,
+                )
+                if issue is not None and not had_open_issue:
+                    scan.bump("odometer_regression")
+            if later[2] > highest[2]:
+                highest = later
 
 
 def run_scan(
-    db: Session, *, actor_label: str | None = None, actor_type: str = "user"
+    db: Session,
+    *,
+    actor_label: str | None = None,
+    actor_type: str = "user",
+    commit: bool = True,
 ) -> ScanResult:
     # The check-then-insert work below spans several rules. Serialise whole scans at the
     # database boundary so API and n8n triggers cannot both observe an empty condition.
@@ -293,7 +332,12 @@ def run_scan(
     scan = ScanResult()
     scan_duplicate_customers(db, scan, _open_issue)
     _scan_missing_required_fields(db, scan)
-    _scan_odometer_regressions(db, scan)
+    _scan_odometer_regressions(
+        db,
+        scan,
+        actor_label=actor_label,
+        actor_type=actor_type,
+    )
     _scan_booking_overlaps(db, scan)
     _scan_vehicle_status_conflicts(db, scan)
     if actor_label is not None:
@@ -305,28 +349,13 @@ def run_scan(
             entity_type="system",
             metadata={"created": scan.created},
         )
-    db.commit()
+    if commit:
+        db.commit()
+    else:
+        db.flush()
     return scan
 
 
-def _load_open_issue(
-    db: Session, public_ref: str, *, lock: bool = True
-) -> DataQualityIssue:
-    statement = select(DataQualityIssue).where(DataQualityIssue.public_ref == public_ref)
-    if lock:
-        statement = statement.with_for_update()
-    issue = db.scalar(statement)
-    if issue is None:
-        raise AppError("ISSUE_NOT_FOUND", "Data quality issue not found.", status_code=404)
-    if issue.status != "open":
-        raise AppError(
-            "ISSUE_NOT_OPEN",
-            f"Issue is '{issue.status}', not 'open'.",
-            status_code=409,
-        )
-    return issue
-
-
 def defer_issue(db: Session, public_ref: str, actor: CurrentUser) -> DataQualityIssue:
     issue = _load_open_issue(db, public_ref)
     issue.status = "deferred"
@@ -456,115 +485,6 @@ def provide_missing_fields(
     return issue
 
 
-def resolve_odometer_regression(
-    db: Session, public_ref: str, body: ResolveOdometerRegressionRequest, actor: CurrentUser
-) -> DataQualityIssue:
-    issue = _load_open_issue(db, public_ref)
-    if issue.rule_type != "odometer_regression":
-        raise AppError(
-            "NOT_AN_ODOMETER_ISSUE",
-            "This issue is not an odometer_regression issue.",
-            status_code=409,
-        )
-    # Lock order is booking -> vehicle everywhere (checkout, return, reschedule); taking
-    # the vehicle lock first here would be a deadlock waiting to happen under concurrency.
-    booking: Booking | None = None
-    if body.decision != "retain_canonical":
-        related_refs = issue.evidence_json.get("related_refs", [])
-        if body.booking_ref not in related_refs:
-            raise AppError(
-                "INVALID_BOOKING_REFERENCE",
-                "booking_ref must be one of this issue's related bookings.",
-                status_code=422,
-            )
-        if body.corrected_odometer_km is None:
-            raise AppError(
-                "CORRECTED_VALUE_REQUIRED",
-                "corrected_odometer_km is required when correcting a reading.",
-                status_code=422,
-            )
-        booking = db.scalar(
-            select(Booking).where(Booking.public_ref == body.booking_ref).with_for_update()
-        )
-        if booking is None:
-            raise AppError(
-                "BOOKING_NOT_FOUND", "The booking to correct was not found.", status_code=404
-            )
-    vehicle = db.scalar(select(Vehicle).where(Vehicle.id == issue.entity_id).with_for_update())
-    if vehicle is None:
-        raise AppError(
-            "VEHICLE_NOT_FOUND", "The vehicle for this issue was not found.", status_code=404
-        )
-
-    correlation_id = uuid.uuid4()
-
-    if body.decision == "retain_canonical":
-        record_audit_event(
-            db,
-            actor_type="user",
-            actor_label=actor.display_name,
-            action="data_quality_odometer_retained",
-            entity_type="vehicle",
-            entity_id=vehicle.id,
-            correlation_id=correlation_id,
-            metadata={"issue_ref": issue.public_ref, "canonical_odometer_km": vehicle.odometer_km},
-        )
-    else:
-        assert booking is not None and body.corrected_odometer_km is not None
-        # Never silently lower the canonical odometer: a correction must be at or above
-        # the current canonical value, otherwise it would just create a new regression.
-        if body.corrected_odometer_km < vehicle.odometer_km:
-            raise AppError(
-                "CORRECTION_BELOW_CANONICAL",
-                (
-                    f"Corrected value {body.corrected_odometer_km} km is still below the "
-                    f"canonical {vehicle.odometer_km} km; it would not resolve the regression."
-                ),
-                status_code=422,
-            )
-
-        before = {
-            "booking_end_odometer_km": booking.end_odometer_km,
-            "vehicle_odometer_km": vehicle.odometer_km,
-        }
-        booking.end_odometer_km = body.corrected_odometer_km
-        vehicle.odometer_km = body.corrected_odometer_km
-        vehicle.version += 1
-        record_audit_event(
-            db,
-            actor_type="user",
-            actor_label=actor.display_name,
-            action="data_quality_odometer_corrected",
-            entity_type="vehicle",
-            entity_id=vehicle.id,
-            correlation_id=correlation_id,
-            before=before,
-            after={
-                "booking_end_odometer_km": booking.end_odometer_km,
-                "vehicle_odometer_km": vehicle.odometer_km,
-            },
-            metadata={"issue_ref": issue.public_ref, "booking_ref": booking.public_ref},
-        )
-
-    issue.status = "resolved"
-    issue.resolved_at = datetime.now(UTC)
-    issue.resolved_by = actor.display_name
-    record_audit_event(
-        db,
-        actor_type="user",
-        actor_label=actor.display_name,
-        action="data_quality_issue_resolved",
-        entity_type="data_quality_issue",
-        entity_id=issue.id,
-        correlation_id=correlation_id,
-        before={"status": "open"},
-        after={"status": "resolved"},
-        metadata={"decision": body.decision, "note": body.note},
-    )
-    db.commit()
-    return issue
-
-
 def resolve_booking_overlap(
     db: Session, public_ref: str, booking_ref: str, note: str | None, actor: CurrentUser
 ) -> DataQualityIssue:

backend/app/services/data_quality_common.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime, timedelta
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.core.errors import AppError
+from app.models.data_quality import DataQualityIssue
+
+
+def issue_due_at(detected_at: datetime, severity: str) -> datetime:
+    """Return the local operational SLA deadline for a newly detected issue."""
+    return detected_at + {
+        "high": timedelta(hours=4),
+        "medium": timedelta(days=1),
+        "low": timedelta(days=3),
+    }.get(severity, timedelta(days=1))
+
+
+def has_open_issue(
+    db: Session,
+    rule_type: str,
+    entity_type: str,
+    entity_id: uuid.UUID,
+) -> bool:
+    return (
+        db.scalar(
+            select(DataQualityIssue.id).where(
+                DataQualityIssue.rule_type == rule_type,
+                DataQualityIssue.entity_type == entity_type,
+                DataQualityIssue.entity_id == entity_id,
+                DataQualityIssue.status == "open",
+            )
+        )
+        is not None
+    )
+
+
+def new_scan_ref(prefix: str) -> str:
+    """Generate a stable human-readable prefix with a concurrent-safe suffix."""
+    return f"{prefix}-{uuid.uuid4().hex[:10].upper()}"
+
+
+def load_open_issue(db: Session, public_ref: str, *, lock: bool = True) -> DataQualityIssue:
+    statement = select(DataQualityIssue).where(DataQualityIssue.public_ref == public_ref)
+    if lock:
+        statement = statement.with_for_update().execution_options(populate_existing=True)
+    issue = db.scalar(statement)
+    if issue is None:
+        raise AppError("ISSUE_NOT_FOUND", "Data quality issue not found.", status_code=404)
+    if issue.status != "open":
+        raise AppError(
+            "ISSUE_NOT_OPEN",
+            f"Issue is '{issue.status}', not 'open'.",
+            status_code=409,
+        )
+    return issue

backend/app/services/data_quality_duplicate_scan.py

@@ -90,9 +90,7 @@ def scan_duplicate_customers[ScanType: ScanAccumulator](
         ratio = SequenceMatcher(None, name_a, name_b).ratio()
         if ratio >= 0.5:
             score += round(ratio * 30)
-            signals.append(
-                {"code": "duplicate.similar_name", "params": {"score": round(ratio, 2)}}
-            )
+            signals.append({"code": "duplicate.similar_name", "params": {"score": round(ratio, 2)}})
             summary_parts.append("similar name")
 
         if score >= DUPLICATE_THRESHOLD:

backend/app/services/data_quality_odometer.py

@@ -0,0 +1,507 @@
+from __future__ import annotations
+
+import uuid
+from datetime import UTC, datetime
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.core.errors import AppError
+from app.models.booking import Booking
+from app.models.data_quality import DataQualityIssue
+from app.models.inspection import Inspection
+from app.models.vehicle import Vehicle
+from app.schemas import CurrentUser, ResolveOdometerRegressionRequest
+from app.services.audit import record_audit_event
+from app.services.data_quality_common import issue_due_at, load_open_issue, new_scan_ref
+
+
+def _odometer_fingerprint(
+    *,
+    source_type: str,
+    later_ref: str,
+    later_km: int,
+) -> dict[str, str | int]:
+    """Stable identity for one reviewed regression, independent of issue IDs."""
+    return {
+        "source_type": source_type,
+        "later_ref": later_ref,
+        "later_km": later_km,
+    }
+
+
+def _was_odometer_regression_retained(
+    db: Session,
+    *,
+    vehicle_id: uuid.UUID,
+    fingerprint: dict[str, str | int],
+) -> bool:
+    reviewed = db.scalars(
+        select(DataQualityIssue).where(
+            DataQualityIssue.rule_type == "odometer_regression",
+            DataQualityIssue.entity_type == "vehicle",
+            DataQualityIssue.entity_id == vehicle_id,
+            DataQualityIssue.status == "resolved",
+        )
+    ).all()
+    return any(
+        issue.evidence_json.get("resolution_decision") == "retain_canonical"
+        and fingerprint in issue.evidence_json.get("retained_odometer_fingerprints", [])
+        for issue in reviewed
+    )
+
+
+def open_odometer_regression_issue(
+    db: Session,
+    *,
+    vehicle: Vehicle,
+    reading_ref: str,
+    reading_km: int,
+    canonical_km: int,
+    source_type: str,
+    related_refs: list[str],
+    correctable_booking_refs: list[str] | None = None,
+    canonical_ref: str | None = None,
+    detected_at: datetime | None = None,
+    public_ref: str | None = None,
+    actor_label: str | None = None,
+    actor_type: str = "user",
+    correlation_id: uuid.UUID | None = None,
+) -> DataQualityIssue | None:
+    """Open one explainable DQ-03 issue while the caller holds the vehicle lock."""
+    if reading_km >= canonical_km:
+        return None
+    earlier_ref = canonical_ref or vehicle.public_ref
+    fingerprint = _odometer_fingerprint(
+        source_type=source_type,
+        later_ref=reading_ref,
+        later_km=reading_km,
+    )
+    # A manager's explicit "retain canonical" decision acknowledges this exact source
+    # fact. Reopening it on every scheduled scan would create churn; only changed or new
+    # evidence (and therefore a different fingerprint) is actionable again.
+    if _was_odometer_regression_retained(
+        db,
+        vehicle_id=vehicle.id,
+        fingerprint=fingerprint,
+    ):
+        return None
+    existing = db.scalar(
+        select(DataQualityIssue)
+        .where(
+            DataQualityIssue.rule_type == "odometer_regression",
+            DataQualityIssue.entity_type == "vehicle",
+            DataQualityIssue.entity_id == vehicle.id,
+            DataQualityIssue.status == "open",
+        )
+        .with_for_update()
+        .execution_options(populate_existing=True)
+    )
+    if existing is not None:
+        before_related_refs = list(existing.evidence_json.get("related_refs", []))
+        before_correctable_refs = list(existing.evidence_json.get("correctable_booking_refs", []))
+        new_signal = {
+            "code": "odometer.regression",
+            "source_type": source_type,
+            "params": {
+                "later_ref": reading_ref,
+                "later_km": reading_km,
+                "earlier_ref": earlier_ref,
+                "earlier_km": canonical_km,
+            },
+        }
+        existing_signals = list(existing.evidence_json.get("signals", []))
+        signal_was_new = not any(
+            isinstance(signal, dict)
+            and isinstance(signal.get("params"), dict)
+            and _odometer_fingerprint(
+                source_type=str(
+                    signal.get("source_type", existing.evidence_json.get("source_type"))
+                ),
+                later_ref=str(signal["params"].get("later_ref")),
+                later_km=signal["params"].get("later_km"),
+            )
+            == fingerprint
+            for signal in existing_signals
+            if isinstance(signal, dict)
+            and isinstance(signal.get("params"), dict)
+            and isinstance(signal["params"].get("later_km"), int)
+        )
+        if signal_was_new:
+            existing_signals.append(new_signal)
+        merged_related_refs = list(
+            dict.fromkeys([*before_related_refs, *(related_refs if signal_was_new else [])])
+        )
+        merged_correctable_refs = list(
+            dict.fromkeys([*before_correctable_refs, *(correctable_booking_refs or [])])
+        )
+        if (
+            not signal_was_new
+            and merged_related_refs == before_related_refs
+            and merged_correctable_refs == before_correctable_refs
+        ):
+            return existing
+        source_types = list(existing.evidence_json.get("source_types", []))
+        previous_source_type = existing.evidence_json.get("source_type")
+        if (
+            isinstance(previous_source_type, str)
+            and previous_source_type != "multiple"
+            and previous_source_type not in source_types
+        ):
+            source_types.append(previous_source_type)
+        if source_type not in source_types:
+            source_types.append(source_type)
+        existing.evidence_json = {
+            **existing.evidence_json,
+            "summary": (
+                f"{source_type.title()} {reading_ref} recorded {reading_km} km, below "
+                f"the canonical {canonical_km} km for {vehicle.public_ref}."
+            ),
+            "related_refs": merged_related_refs,
+            "correctable_booking_refs": merged_correctable_refs,
+            "source_type": source_type if len(source_types) == 1 else "multiple",
+            "source_types": source_types,
+            "signals": existing_signals,
+        }
+        if actor_label is not None and (
+            merged_related_refs != before_related_refs
+            or merged_correctable_refs != before_correctable_refs
+            or signal_was_new
+        ):
+            record_audit_event(
+                db,
+                actor_type=actor_type,
+                actor_label=actor_label,
+                action="data_quality_issue_evidence_updated",
+                entity_type="data_quality_issue",
+                entity_id=existing.id,
+                correlation_id=correlation_id,
+                before={
+                    "related_refs": before_related_refs,
+                    "correctable_booking_refs": before_correctable_refs,
+                },
+                after={
+                    "related_refs": merged_related_refs,
+                    "correctable_booking_refs": merged_correctable_refs,
+                },
+                metadata={"vehicle_ref": vehicle.public_ref, "reading_ref": reading_ref},
+            )
+        return existing
+    now = detected_at or datetime.now(UTC)
+    previous = db.scalar(
+        select(DataQualityIssue)
+        .where(
+            DataQualityIssue.rule_type == "odometer_regression",
+            DataQualityIssue.entity_type == "vehicle",
+            DataQualityIssue.entity_id == vehicle.id,
+            DataQualityIssue.status != "open",
+        )
+        .order_by(DataQualityIssue.detected_at.desc())
+    )
+    evidence = {
+        "summary": (
+            f"{source_type.title()} {reading_ref} recorded {reading_km} km, below "
+            f"the canonical {canonical_km} km for {vehicle.public_ref}."
+        ),
+        "entity_ref": vehicle.public_ref,
+        "related_refs": related_refs,
+        "correctable_booking_refs": correctable_booking_refs or [],
+        "source_type": source_type,
+        "source_types": [source_type],
+        "signals": [
+            {
+                "code": "odometer.regression",
+                "source_type": source_type,
+                "params": {
+                    "later_ref": reading_ref,
+                    "later_km": reading_km,
+                    "earlier_ref": earlier_ref,
+                    "earlier_km": canonical_km,
+                },
+            }
+        ],
+    }
+    if previous is not None:
+        evidence["reopened_from"] = previous.public_ref
+        evidence["previous_decision"] = previous.status
+    issue = DataQualityIssue(
+        public_ref=public_ref or new_scan_ref("DQ-ODO"),
+        rule_type="odometer_regression",
+        entity_type="vehicle",
+        entity_id=vehicle.id,
+        severity="medium",
+        status="open",
+        evidence_json=evidence,
+        proposed_action_json={},
+        detected_at=now,
+        due_at=issue_due_at(now, "medium"),
+    )
+    db.add(issue)
+    db.flush()
+    if actor_label is not None:
+        record_audit_event(
+            db,
+            actor_type=actor_type,
+            actor_label=actor_label,
+            action="data_quality_issue_created",
+            entity_type="data_quality_issue",
+            entity_id=issue.id,
+            correlation_id=correlation_id,
+            after={"status": "open", "rule_type": "odometer_regression"},
+            metadata={"vehicle_ref": vehicle.public_ref, "reading_ref": reading_ref},
+        )
+    return issue
+
+
+def resolve_odometer_regression(
+    db: Session, public_ref: str, body: ResolveOdometerRegressionRequest, actor: CurrentUser
+) -> DataQualityIssue:
+    # Read the routing data without a row lock first. The canonical mutation order is
+    # booking -> vehicle -> issue -> inspection everywhere, matching checkout/return.
+    # Locking the issue before the booking creates a resolver-vs-return deadlock.
+    issue_snapshot = load_open_issue(db, public_ref, lock=False)
+    if issue_snapshot.rule_type != "odometer_regression":
+        raise AppError(
+            "NOT_AN_ODOMETER_ISSUE",
+            "This issue is not an odometer_regression issue.",
+            status_code=409,
+        )
+
+    def correctable_refs(issue: DataQualityIssue) -> list[str]:
+        if "correctable_booking_refs" in issue.evidence_json:
+            refs = issue.evidence_json.get("correctable_booking_refs", [])
+        else:
+            # Backward compatibility for issues created before source-aware evidence.
+            refs = [
+                ref
+                for ref in issue.evidence_json.get("related_refs", [])
+                if isinstance(ref, str) and ref.startswith("BK-")
+            ]
+        return [ref for ref in refs if isinstance(ref, str)]
+
+    booking: Booking | None = None
+    if body.decision != "retain_canonical":
+        if body.booking_ref not in correctable_refs(issue_snapshot):
+            raise AppError(
+                "INVALID_BOOKING_REFERENCE",
+                "booking_ref must be one of this issue's related bookings.",
+                status_code=422,
+            )
+        if body.corrected_odometer_km is None:
+            raise AppError(
+                "CORRECTED_VALUE_REQUIRED",
+                "corrected_odometer_km is required when correcting a reading.",
+                status_code=422,
+            )
+        booking = db.scalar(
+            select(Booking).where(Booking.public_ref == body.booking_ref).with_for_update()
+        )
+        if booking is None:
+            raise AppError(
+                "BOOKING_NOT_FOUND", "The booking to correct was not found.", status_code=404
+            )
+    vehicle = db.scalar(
+        select(Vehicle).where(Vehicle.id == issue_snapshot.entity_id).with_for_update()
+    )
+    if vehicle is None:
+        raise AppError(
+            "VEHICLE_NOT_FOUND", "The vehicle for this issue was not found.", status_code=404
+        )
+
+    # A return or scan may have appended evidence while we waited for the domain locks.
+    # Lock and refresh the issue only now, then revalidate every decision against that
+    # current evidence instead of resolving a stale snapshot.
+    issue = load_open_issue(db, public_ref)
+    if issue.rule_type != "odometer_regression" or issue.entity_id != vehicle.id:
+        raise AppError(
+            "ISSUE_CHANGED",
+            "The issue changed while the correction was being prepared. Review it again.",
+            status_code=409,
+        )
+    if booking is not None:
+        if booking.vehicle_id != vehicle.id or booking.public_ref not in correctable_refs(issue):
+            raise AppError(
+                "INVALID_BOOKING_REFERENCE",
+                "booking_ref must be one of this issue's related bookings.",
+                status_code=422,
+            )
+
+    correlation_id = uuid.uuid4()
+
+    if body.decision == "retain_canonical":
+        retained_fingerprints: list[dict[str, str | int]] = []
+        fallback_source_type = str(issue.evidence_json.get("source_type", "unknown"))
+        for signal in issue.evidence_json.get("signals", []):
+            if not isinstance(signal, dict) or signal.get("code") != "odometer.regression":
+                continue
+            params = signal.get("params")
+            if not isinstance(params, dict):
+                continue
+            source_type = signal.get("source_type", fallback_source_type)
+            later_ref = params.get("later_ref")
+            later_km = params.get("later_km")
+            earlier_ref = params.get("earlier_ref")
+            earlier_km = params.get("earlier_km")
+            if (
+                isinstance(source_type, str)
+                and isinstance(later_ref, str)
+                and isinstance(later_km, int)
+                and isinstance(earlier_ref, str)
+                and isinstance(earlier_km, int)
+            ):
+                retained_fingerprints.append(
+                    _odometer_fingerprint(
+                        source_type=source_type,
+                        later_ref=later_ref,
+                        later_km=later_km,
+                    )
+                )
+        issue.evidence_json = {
+            **issue.evidence_json,
+            "resolution_decision": "retain_canonical",
+            "retained_odometer_fingerprints": retained_fingerprints,
+        }
+        record_audit_event(
+            db,
+            actor_type="user",
+            actor_label=actor.display_name,
+            action="data_quality_odometer_retained",
+            entity_type="vehicle",
+            entity_id=vehicle.id,
+            correlation_id=correlation_id,
+            metadata={
+                "issue_ref": issue.public_ref,
+                "canonical_odometer_km": vehicle.odometer_km,
+                "retained_fingerprint_count": len(retained_fingerprints),
+            },
+        )
+    else:
+        assert booking is not None and body.corrected_odometer_km is not None
+        # Never silently lower the canonical odometer: a correction must be at or above
+        # the current canonical value, otherwise it would just create a new regression.
+        if body.corrected_odometer_km < vehicle.odometer_km:
+            raise AppError(
+                "CORRECTION_BELOW_CANONICAL",
+                (
+                    f"Corrected value {body.corrected_odometer_km} km is still below the "
+                    f"canonical {vehicle.odometer_km} km; it would not resolve the regression."
+                ),
+                status_code=422,
+            )
+
+        # A returned booking has two persisted representations of the same reading.
+        # Correct every return inspection for the selected booking, including historical
+        # seed rows whose old issue evidence did not yet cite the inspection explicitly.
+        related_inspections = db.scalars(
+            select(Inspection)
+            .where(Inspection.booking_id == booking.id, Inspection.type == "return")
+            .with_for_update()
+        ).all()
+        before = {
+            "booking_end_odometer_km": booking.end_odometer_km,
+            "vehicle_odometer_km": vehicle.odometer_km,
+            "inspection_odometer_km": {
+                inspection.public_ref: inspection.odometer_km for inspection in related_inspections
+            },
+        }
+        booking.end_odometer_km = body.corrected_odometer_km
+        for inspection in related_inspections:
+            inspection.odometer_km = body.corrected_odometer_km
+        vehicle.odometer_km = body.corrected_odometer_km
+        vehicle.version += 1
+        record_audit_event(
+            db,
+            actor_type="user",
+            actor_label=actor.display_name,
+            action="data_quality_odometer_corrected",
+            entity_type="vehicle",
+            entity_id=vehicle.id,
+            correlation_id=correlation_id,
+            before=before,
+            after={
+                "booking_end_odometer_km": booking.end_odometer_km,
+                "vehicle_odometer_km": vehicle.odometer_km,
+                "inspection_odometer_km": {
+                    inspection.public_ref: inspection.odometer_km
+                    for inspection in related_inspections
+                },
+            },
+            metadata={"issue_ref": issue.public_ref, "booking_ref": booking.public_ref},
+        )
+
+    has_remaining_evidence = False
+    if booking is not None:
+        target_refs = {booking.public_ref, *(item.public_ref for item in related_inspections)}
+        before_related = [
+            ref for ref in issue.evidence_json.get("related_refs", []) if isinstance(ref, str)
+        ]
+        before_correctable = correctable_refs(issue)
+        before_signals = [
+            signal for signal in issue.evidence_json.get("signals", []) if isinstance(signal, dict)
+        ]
+        remaining_signals = [
+            signal
+            for signal in before_signals
+            if not (
+                isinstance(signal.get("params"), dict)
+                and signal["params"].get("later_ref") in target_refs
+            )
+        ]
+        remaining_related = [ref for ref in before_related if ref not in target_refs]
+        remaining_correctable = [ref for ref in before_correctable if ref != booking.public_ref]
+        has_remaining_evidence = bool(remaining_signals or remaining_correctable)
+        issue.evidence_json = {
+            **issue.evidence_json,
+            "summary": (
+                "Additional odometer regression evidence remains for review."
+                if has_remaining_evidence
+                else issue.evidence_json.get("summary", "Odometer reading corrected.")
+            ),
+            "related_refs": remaining_related,
+            "correctable_booking_refs": remaining_correctable,
+            "signals": remaining_signals,
+        }
+        if has_remaining_evidence:
+            record_audit_event(
+                db,
+                actor_type="user",
+                actor_label=actor.display_name,
+                action="data_quality_issue_partially_resolved",
+                entity_type="data_quality_issue",
+                entity_id=issue.id,
+                correlation_id=correlation_id,
+                before={
+                    "related_refs": before_related,
+                    "correctable_booking_refs": before_correctable,
+                    "signal_count": len(before_signals),
+                },
+                after={
+                    "related_refs": remaining_related,
+                    "correctable_booking_refs": remaining_correctable,
+                    "signal_count": len(remaining_signals),
+                },
+                metadata={
+                    "decision": body.decision,
+                    "booking_ref": booking.public_ref,
+                    "note": body.note,
+                },
+            )
+
+    if not has_remaining_evidence:
+        issue.status = "resolved"
+        issue.resolved_at = datetime.now(UTC)
+        issue.resolved_by = actor.display_name
+        record_audit_event(
+            db,
+            actor_type="user",
+            actor_label=actor.display_name,
+            action="data_quality_issue_resolved",
+            entity_type="data_quality_issue",
+            entity_id=issue.id,
+            correlation_id=correlation_id,
+            before={"status": "open"},
+            after={"status": "resolved"},
+            metadata={"decision": body.decision, "note": body.note},
+        )
+    db.commit()
+    return issue

backend/app/services/demo_manifest.py

@@ -9,16 +9,28 @@ from app.core.config import get_settings
 from app.models.audit import AuditEvent
 from app.models.booking import Booking
 from app.models.data_quality import DataQualityIssue
-from app.models.outbox import OutboxEvent
+from app.models.outbox import OutboxEvent, is_demo_scenario_failure
 from app.schemas import DemoIntegrationSummaryOut, DemoManifestOut, DemoScenarioOut
 from app.services.integration_status import derive_mcp_hub_status, derive_n8n_status
-from app.services.knowledge import get_knowledge_provider
+from app.services.knowledge import KnowledgeHealth, get_knowledge_provider
 
 settings = get_settings()
 
 _FAILED_DEMO_EVENT_ID = "00000000-0000-4000-8000-000000000020"
 
 
+def _knowledge_scenario_ready(health: KnowledgeHealth) -> bool:
+    """Require a reachable provider and independently verified indexed documents.
+
+    ``source_document_count`` describes local Markdown files, while a sync report only
+    describes an upload attempt. Neither proves that the active provider can retrieve a
+    corpus, so an unavailable verification count remains honestly not ready.
+    """
+    return bool(
+        health.available and health.document_count is not None and health.document_count > 0
+    )
+
+
 def _last_reset(db: Session) -> tuple[datetime | None, str | None]:
     marker = db.scalar(
         select(AuditEvent)
@@ -49,7 +61,8 @@ def _scenarios(db: Session) -> list[DemoScenarioOut]:
     return_ready = bool(booking and booking.status == "active" and booking.end_odometer_km is None)
     duplicate_ready = bool(duplicate_issue and duplicate_issue.status == "open")
     overlap_ready = bool(overlap_issue and overlap_issue.status == "open")
-    automation_ready = bool(failed_run and failed_run.delivery_status == "failed")
+    automation_ready = bool(failed_run and is_demo_scenario_failure(failed_run))
+    knowledge_ready = _knowledge_scenario_ready(knowledge_health)
 
     return [
         DemoScenarioOut(
@@ -119,8 +132,8 @@ def _scenarios(db: Session) -> list[DemoScenarioOut]:
             estimated_minutes=2,
             required_roles=["rental_employee", "operations_manager"],
             start_path="/knowledge",
-            ready=knowledge_health.available,
-            blocked_reason_code=None if knowledge_health.available else "knowledgeUnavailable",
+            ready=knowledge_ready,
+            blocked_reason_code=None if knowledge_ready else "knowledgeUnavailable",
         ),
     ]
 
@@ -145,9 +158,11 @@ def _integrations(db: Session) -> list[DemoIntegrationSummaryOut]:
             key="ragcore",
             status_code=(
                 "operational"
-                if knowledge_health.provider == "ragcore" and knowledge_health.available
+                if knowledge_health.provider == "ragcore"
+                and _knowledge_scenario_ready(knowledge_health)
                 else "demoMode"
-                if knowledge_health.provider == "demo" and knowledge_health.available
+                if knowledge_health.provider == "demo"
+                and _knowledge_scenario_ready(knowledge_health)
                 else "unavailable"
             ),
             detail_code=(
@@ -169,9 +184,7 @@ def _integrations(db: Session) -> list[DemoIntegrationSummaryOut]:
             # "operational" -- same evidence rule the integration status page uses.
             status_code="operational" if mcp_hub.state == "operational" else "notConnected",
             detail_code=(
-                "mcpDetailOperational"
-                if mcp_hub.state == "operational"
-                else "mcpDetailPrepared"
+                "mcpDetailOperational" if mcp_hub.state == "operational" else "mcpDetailPrepared"
             ),
             detail_params={},
         ),

backend/app/services/dispatcher.py

@@ -77,6 +77,14 @@ def _claim_due_events(batch_size: int = 5) -> list[uuid.UUID]:
         for row in rows:
             row.delivery_status = "delivering"
             row.next_attempt_at = lease_deadline
+            # The token is stored inside the internal payload (the wire envelope below
+            # explicitly selects only contract fields). It lets the outcome transaction
+            # prove that this is still the same lease after network I/O. A stale worker
+            # must never overwrite a later reclaim/retry or an idempotent callback.
+            row.payload_json = {
+                **row.payload_json,
+                "_delivery_claim_token": str(uuid.uuid4()),
+            }
         db.commit()
         return claimed_ids
     finally:
@@ -109,6 +117,9 @@ def _deliver_one(event_id: uuid.UUID) -> None:
             wire_event = None
             payload_error = f"Malformed outbox payload, missing key {exc}"
         attempts = event.attempts
+        claim_token = event.payload_json.get("_delivery_claim_token")
+        if event.delivery_status != "delivering" or not isinstance(claim_token, str):
+            return
     finally:
         db.close()
 
@@ -130,9 +141,33 @@ def _deliver_one(event_id: uuid.UUID) -> None:
             except ValueError:
                 body = None
             if isinstance(body, dict):
-                success = bool(body.get("ok", True))
-                error = None if success else f"n8n reported failure: {body}"
-                error_code = None if success else "remoteReportedFailure"
+                acknowledged = body.get("ok") is True
+                response_event_id = body.get("event_id")
+                event_id_matches = response_event_id == str(event_id)
+                result = body.get("result")
+                execution_id = result.get("execution_id") if isinstance(result, dict) else None
+                execution_id_valid = isinstance(execution_id, str) and bool(execution_id.strip())
+                success = acknowledged and event_id_matches and execution_id_valid
+                if success:
+                    error = None
+                    error_code = None
+                elif not acknowledged:
+                    error = (
+                        "n8n response did not explicitly acknowledge the event with ok=true: "
+                        f"{body}"
+                    )
+                    error_code = (
+                        "remoteReportedFailure" if body.get("ok") is False else "malformedResponse"
+                    )
+                elif not event_id_matches:
+                    error = (
+                        "n8n acknowledged a different event ID "
+                        f"(expected {event_id}, received {response_event_id!r})"
+                    )
+                    error_code = "mismatchedEventId"
+                else:
+                    error = "n8n response omitted a valid result.execution_id"
+                    error_code = "malformedResponse"
             else:
                 # A 2xx status with a non-object (or unparsable) body means the workflow
                 # itself errored before its "Respond to Webhook" node ran -- n8n's default
@@ -152,16 +187,35 @@ def _deliver_one(event_id: uuid.UUID) -> None:
 
     db = SessionLocal()
     try:
-        event = db.get(OutboxEvent, event_id)
+        event = db.scalar(
+            select(OutboxEvent).where(OutboxEvent.event_id == event_id).with_for_update()
+        )
         if event is None:
             return
+        if (
+            event.delivery_status != "delivering"
+            or event.attempts != attempts
+            or event.payload_json.get("_delivery_claim_token") != claim_token
+        ):
+            logger.info(
+                "Ignoring stale delivery outcome for event %s because lease ownership changed",
+                event_id,
+            )
+            return
         event.attempts = attempts + 1
+        event.payload_json = {
+            key: value
+            for key, value in event.payload_json.items()
+            if key != "_delivery_claim_token"
+        }
         if success:
             event.delivery_status = "succeeded"
             event.last_error = None
             event.last_error_code = None
             event.next_attempt_at = None
-            event.external_run_id = str((body or {}).get("event_id", event_id))
+            result = (body or {}).get("result")
+            execution_id = result.get("execution_id") if isinstance(result, dict) else None
+            event.external_run_id = execution_id if isinstance(execution_id, str) else None
         else:
             event.last_error = (error or "delivery failed")[:2000]
             event.last_error_code = error_code or "unknownError"

backend/app/services/integration_status.py

@@ -7,7 +7,7 @@ from datetime import UTC, datetime, timedelta
 from typing import Any, Literal
 
 import httpx
-from sqlalchemy import Row, func, select
+from sqlalchemy import Row, func, or_, select
 from sqlalchemy.orm import Session
 
 from app.core.config import get_settings
@@ -93,7 +93,10 @@ def derive_n8n_status(db: Session) -> N8nIntegrationStatus:
     latest_failure_at = db.scalar(
         select(func.max(OutboxEvent.updated_at)).where(
             OutboxEvent.delivery_status == "failed",
-            OutboxEvent.last_error_code != DEMO_SCENARIO_ERROR_CODE,
+            or_(
+                OutboxEvent.last_error_code.is_(None),
+                OutboxEvent.last_error_code != DEMO_SCENARIO_ERROR_CODE,
+            ),
         )
     )
     latest_demo_scenario_at = db.scalar(
@@ -106,11 +109,17 @@ def derive_n8n_status(db: Session) -> N8nIntegrationStatus:
     state: Literal["disabled", "unavailable", "degraded", "operational", "no_evidence"]
     if not settings.n8n_dispatch_enabled:
         state = "disabled"
+    elif not settings.n8n_webhook_url:
+        # Persisted history does not make a currently unconfigured dispatcher green.
+        state = "unavailable"
     elif unexpected_failed > 0 and succeeded == 0:
         state = "unavailable"
     elif unexpected_failed > 0:
         state = "degraded"
-    elif succeeded > 0 or pending > 0 or delivering > 0:
+    # Queued/in-flight work proves only that MobilityOps has work for the dispatcher;
+    # it does not prove that n8n has ever accepted a delivery.  A green state requires
+    # at least one persisted successful round trip.
+    elif succeeded > 0:
         state = "operational"
     else:
         state = "no_evidence"
@@ -128,8 +137,14 @@ def derive_n8n_status(db: Session) -> N8nIntegrationStatus:
     # it finishes uploading procedures to RAGcore (app/api/routers/integrations.py::
     # procedures_sync_result), the same "the workflow's own callback is the evidence"
     # pattern the scheduled scan and error handler already use below.
-    latest_procedure_sync_at = db.scalar(
-        select(func.max(AuditEvent.occurred_at)).where(AuditEvent.action == "n8n_procedures_synced")
+    latest_procedure_sync_row = db.execute(
+        select(AuditEvent.occurred_at, AuditEvent.after_json, AuditEvent.metadata_json)
+        .where(AuditEvent.action == "n8n_procedures_synced")
+        .order_by(AuditEvent.occurred_at.desc())
+        .limit(1)
+    ).first()
+    latest_procedure_sync_at = (
+        latest_procedure_sync_row[0] if latest_procedure_sync_row is not None else None
     )
 
     # Error handler evidence: registrations posted by the "Fleet Ops — Workflow Error
@@ -198,6 +213,24 @@ def derive_n8n_status(db: Session) -> N8nIntegrationStatus:
             seen_at = failure_signal[0]
             last_status = "failed"
             execution_id = failure_signal[1]
+        if name == "Fleet Ops — RAGcore Procedure Sync" and latest_procedure_sync_row:
+            sync_at, sync_result, sync_metadata = latest_procedure_sync_row
+            synced = (sync_result or {}).get("synced", 0)
+            failed_syncs = (sync_result or {}).get("failed", 0)
+            # The result callback is authoritative for corpus delivery. A generic
+            # succeeded heartbeat cannot turn a zero/partial upload green.
+            sync_result_failed = (
+                not isinstance(synced, int)
+                or not isinstance(failed_syncs, int)
+                or synced <= 0
+                or failed_syncs > 0
+            )
+            if sync_result_failed:
+                last_status = "failed"
+            if seen_at is None or sync_at > seen_at:
+                seen_at = sync_at
+            if sync_result_failed:
+                execution_id = (sync_metadata or {}).get("execution_id")
         workflow_state: Literal["no_evidence", "healthy", "stale", "failed"]
         if seen_at is None:
             workflow_state = "no_evidence"
@@ -265,16 +298,20 @@ def derive_mcp_hub_status(db: Session) -> McpHubIntegrationStatus:
     last_client = latest_call_row[1] if latest_call_row else None
     last_tool = (latest_call_row[2] or {}).get("tool") if latest_call_row else None
 
+    hub_reachable = _check_hub_reachable()
+
     state: Literal["not_configured", "no_evidence", "operational"]
     if not settings.mcp_hub_registration_enabled:
         state = "not_configured"
-    elif total_calls > 0:
+    elif total_calls > 0 and hub_reachable is not False:
         state = "operational"
     else:
+        # Historical tool calls remain useful telemetry, but cannot support a current
+        # operational claim when the configured Hub health endpoint is unreachable.
+        # ``hub_reachable`` stays available separately so consumers can distinguish
+        # this from a provider that simply has no call evidence yet.
         state = "no_evidence"
 
-    hub_reachable = _check_hub_reachable()
-
     return McpHubIntegrationStatus(
         registration_enabled=settings.mcp_hub_registration_enabled,
         state=state,

backend/app/services/knowledge/ragcore.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+import hashlib
+import re
+import uuid
 from concurrent.futures import ThreadPoolExecutor
 from pathlib import Path
 from threading import Lock
@@ -13,6 +16,10 @@ from app.services.knowledge import EvidenceState, GroundedAnswer, KnowledgeHealt
 from app.services.knowledge.procedures import ProcedureDocument, iter_procedure_documents
 
 _GROUNDED_ANSWERABILITY = {"answerable", "partially_answerable"}
+_ANSWERABILITY_STATES = _GROUNDED_ANSWERABILITY | {
+    "not_answerable",
+    "conflicting_evidence",
+}
 
 # Mirrors DemoKnowledgeProvider's own extractive template in spirit: a real cited
 # excerpt wrapped in a fixed sentence, never a generated summary. Used only as a
@@ -47,6 +54,11 @@ _DOMAIN_CONCEPTS: dict[str, tuple[str, ...]] = {
     "availability": ("available", "availability", "beschikbaar", "disponible", "disponibilité"),
     "technical": ("technical", "warning", "technisch", "waarschuwing", "technique", "alerte"),
 }
+_ANSWERABLE_INTENT_CONCEPTS = frozenset(_DOMAIN_CONCEPTS) - {"vehicle", "customer"}
+
+
+def _normalize_evidence_text(value: str) -> str:
+    return " ".join(re.findall(r"\w+", value.casefold()))
 
 
 def _question_concepts(question: str) -> set[str]:
@@ -93,7 +105,9 @@ def _rank_sources_for_concepts(sources: list[SourceCard], concepts: set[str]) ->
     )
 
 
-def _retrieval_score(result: dict) -> float | None:
+def _retrieval_score(result: object) -> float | None:
+    if not isinstance(result, dict):
+        return None
     scores = result.get("scores")
     if not isinstance(scores, dict):
         return None
@@ -124,23 +138,81 @@ class RAGcoreKnowledgeProvider:
     excerpt RAGcore's own search actually found, wrapped in the same fixed citation
     template `DemoKnowledgeProvider` uses -- never a fabricated summary.
 
-    Known gap, not fixable from this side: RAGcore's ingest pipeline currently tags every
-    chunk's `language` payload field as `"en"` regardless of actual document language (the
-    `/v1/uploads` contract has no per-file language field for a caller to set correctly).
-    Filtering search/answer requests by requested UI language would therefore silently
-    exclude genuinely-relevant nl-BE/fr-BE content, so this adapter deliberately does not
-    filter by language -- retrieval relies on the embedding model's cross-lingual matching.
+    Retrieval is scoped to the stable RAGcore ``source_id`` values owned by Fleet Ops for
+    the requested UI language. Returned internal document/version UUIDs are deliberately
+    not treated as Fleet Ops identifiers: every citation must instead prove the complete
+    managed-source chain (source id, URI, locator, checksum and extractive local text).
     """
 
     name = "ragcore"
 
     def __init__(self) -> None:
         self._settings = get_settings()
+        self._managed_documents_by_source_id: dict[str, ProcedureDocument] = {}
+        for document in iter_procedure_documents(Path(self._settings.knowledge_dir)):
+            self._managed_documents_by_source_id[document.source_id] = document
         self._verification_cache: dict[str, tuple[float, int]] = {}
         self._verification_lock = Lock()
         self._answers_circuit_lock = Lock()
         self._answers_circuit_open_until = 0.0
 
+    def _managed_source(self, citation: object, language: str) -> SourceCard | None:
+        if not isinstance(citation, dict):
+            return None
+        source_id = citation.get("source_id")
+        if not isinstance(source_id, str):
+            return None
+        document = self._managed_documents_by_source_id.get(str(source_id))
+        if document is None or document.language != language:
+            return None
+        if citation.get("locator") != f"{document.document_id}.md":
+            return None
+        if citation.get("source_uri") != f"ragcore://source/{document.source_id}":
+            return None
+        for field_name in ("id", "document_id", "document_version_id"):
+            value = citation.get(field_name)
+            if not isinstance(value, str):
+                return None
+            try:
+                parsed = uuid.UUID(value)
+            except (ValueError, TypeError, AttributeError):
+                return None
+            if parsed.int == 0:
+                return None
+        if not isinstance(citation.get("title"), str):
+            return None
+        section = citation.get("section")
+        if section is not None and not isinstance(section, str):
+            return None
+        excerpt = citation.get("excerpt")
+        if not isinstance(excerpt, str) or not excerpt.strip():
+            return None
+        expected_hash = hashlib.sha256(excerpt.encode("utf-8")).hexdigest()
+        if citation.get("excerpt_sha256") != expected_hash:
+            return None
+        # RAGcore owns chunking, but the cited excerpt must still be extractive evidence
+        # from the authoritative local procedure. Token normalization tolerates Markdown
+        # punctuation/whitespace while rejecting provider text that was never uploaded.
+        normalized_excerpt = _normalize_evidence_text(excerpt)
+        if not normalized_excerpt or normalized_excerpt not in _normalize_evidence_text(
+            document.content
+        ):
+            return None
+        return SourceCard(
+            document_id=document.document_id,
+            title=document.title,
+            version=document.version,
+            section=section or "",
+            excerpt=excerpt,
+        )
+
+    def _managed_source_ids(self, language: str) -> list[str]:
+        return [
+            document.source_id
+            for document in self._managed_documents_by_source_id.values()
+            if document.language == language
+        ]
+
     def _answers_circuit_is_open(self) -> bool:
         with self._answers_circuit_lock:
             return monotonic() < self._answers_circuit_open_until
@@ -284,7 +356,7 @@ class RAGcoreKnowledgeProvider:
         if self._answers_circuit_is_open():
             KNOWLEDGE_PROVIDER_REQUESTS.labels("answers", "circuit_open").inc()
         else:
-            answered = self._ask_via_answers(question, correlation_id)
+            answered = self._ask_via_answers(question, correlation_id, language)
             if answered is not None:
                 return answered
         # /v1/answers itself is unavailable (non-2xx or unreachable) -- fall back to
@@ -295,7 +367,9 @@ class RAGcoreKnowledgeProvider:
         # generation step.
         return self._ask_via_search_fallback(question, correlation_id, language)
 
-    def _ask_via_answers(self, question: str, correlation_id: str) -> GroundedAnswer | None:
+    def _ask_via_answers(
+        self, question: str, correlation_id: str, language: str
+    ) -> GroundedAnswer | None:
         """Returns None (not a GroundedAnswer) when /v1/answers itself is unavailable,
         so the caller can fall back to search -- as opposed to a real 200 response
         classifying the question as insufficiently answerable, which is a genuine,
@@ -307,6 +381,7 @@ class RAGcoreKnowledgeProvider:
                     json={
                         "query": question,
                         "requested_space_ids": [self._settings.ragcore_space_id],
+                        "filters": {"source_ids": self._managed_source_ids(language)},
                     },
                 )
                 if response.status_code != 200:
@@ -320,25 +395,73 @@ class RAGcoreKnowledgeProvider:
             return None
 
         try:
-            citations = {c["id"]: c for c in body.get("citations", [])}
-            sources = [
-                SourceCard(
-                    document_id=str(citation["document_id"]),
-                    title=citation["title"],
-                    version=str(citation["document_version_id"]),
-                    section=citation.get("section") or "",
-                    excerpt=citation["excerpt"],
-                )
-                for citation in citations.values()
+            if not isinstance(body, dict):
+                raise TypeError("answer response must be an object")
+            # Validate the provider's complete AnswerResponse contract before trusting
+            # generated prose. These IDs and claim bindings are the evidence that RAGcore
+            # ran its deterministic claim/citation validator; one unrelated but otherwise
+            # valid citation must never make arbitrary answer text appear grounded.
+            uuid.UUID(str(body["answer_id"]))
+            uuid.UUID(str(body["retrieval_run_id"]))
+            raw_citations = body.get("citations", [])
+            if not isinstance(raw_citations, list):
+                raise TypeError("citations must be a list")
+            citation_ids: set[uuid.UUID] = set()
+            for citation in raw_citations:
+                if not isinstance(citation, dict):
+                    raise TypeError("citation must be an object")
+                citation_ids.add(uuid.UUID(str(citation["id"])))
+            raw_claims = body["claims"]
+            if not isinstance(raw_claims, list):
+                raise TypeError("claims must be a list")
+            claims_are_bound = bool(raw_claims)
+            answer_text = body.get("answer")
+            for claim in raw_claims:
+                if not isinstance(claim, dict):
+                    raise TypeError("claim must be an object")
+                claim_text = claim.get("text")
+                claim_citation_ids = claim.get("citation_ids")
+                if (
+                    not isinstance(claim_text, str)
+                    or not claim_text.strip()
+                    or not isinstance(answer_text, str)
+                    or claim_text.strip() not in answer_text
+                    or not isinstance(claim_citation_ids, list)
+                    or not claim_citation_ids
+                ):
+                    claims_are_bound = False
+                    continue
+                try:
+                    bound_ids = {uuid.UUID(str(item)) for item in claim_citation_ids}
+                except (TypeError, ValueError):
+                    claims_are_bound = False
+                    continue
+                if not bound_ids.issubset(citation_ids):
+                    claims_are_bound = False
+            mapped_sources = [
+                source
+                for citation in raw_citations
+                if (source := self._managed_source(citation, language)) is not None
             ]
-            sources = _deduplicate_sources(sources)
+            citations_are_managed = len(mapped_sources) == len(raw_citations)
+            sources = _deduplicate_sources(mapped_sources)
             answerability = body.get("answerability", "not_answerable")
-            is_grounded = answerability in _GROUNDED_ANSWERABILITY and sources
+            if answerability not in _ANSWERABILITY_STATES:
+                raise TypeError("answerability is invalid")
+            if not isinstance(answer_text, str):
+                raise TypeError("answer must be a string")
+            is_grounded = (
+                answerability in _GROUNDED_ANSWERABILITY
+                and bool(sources)
+                and citations_are_managed
+                and claims_are_bound
+                and bool(answer_text.strip())
+            )
             evidence_state: EvidenceState = "grounded" if is_grounded else "insufficient"
             KNOWLEDGE_PROVIDER_REQUESTS.labels("answers", evidence_state).inc()
             self._close_answers_circuit()
             return GroundedAnswer(
-                answer=body.get("answer", "") if evidence_state == "grounded" else "",
+                answer=answer_text if evidence_state == "grounded" else "",
                 evidence_state=evidence_state,
                 sources=sources if evidence_state == "grounded" else [],
                 provider=self.name,
@@ -366,6 +489,7 @@ class RAGcoreKnowledgeProvider:
                     json={
                         "query": question,
                         "requested_space_ids": [self._settings.ragcore_space_id],
+                        "filters": {"source_ids": self._managed_source_ids(language)},
                         "max_results": 5,
                     },
                 )
@@ -378,24 +502,24 @@ class RAGcoreKnowledgeProvider:
             return unavailable
 
         try:
+            if not isinstance(body, dict):
+                raise TypeError("search response must be an object")
             results = body.get("results", [])
             if not isinstance(results, list):
                 raise TypeError("results must be a list")
             sources = [
-                SourceCard(
-                    document_id=str(result["citation"]["document_id"]),
-                    title=result["citation"]["title"],
-                    version=str(result["citation"]["document_version_id"]),
-                    section=result["citation"].get("section") or "",
-                    excerpt=result["citation"]["excerpt"],
-                )
+                source
                 for result in results
+                if isinstance(result, dict)
+                and (source := self._managed_source(result.get("citation"), language)) is not None
             ]
         except (TypeError, KeyError, ValueError):
             KNOWLEDGE_PROVIDER_REQUESTS.labels("search", "malformed").inc()
             return unavailable
 
         for result in results:
+            if not isinstance(result, dict):
+                continue
             score = _retrieval_score(result)
             if score is not None:
                 KNOWLEDGE_RETRIEVAL_SCORE.observe(score)
@@ -403,15 +527,11 @@ class RAGcoreKnowledgeProvider:
         all_sources = _deduplicate_sources(sources)
         concepts = _question_concepts(question)
         qualified_sources = [
-            SourceCard(
-                document_id=str(result["citation"]["document_id"]),
-                title=result["citation"]["title"],
-                version=str(result["citation"]["document_version_id"]),
-                section=result["citation"].get("section") or "",
-                excerpt=result["citation"]["excerpt"],
-            )
+            source
             for result in results
-            if (_retrieval_score(result) or 0.0) >= self._settings.ragcore_min_search_score
+            if isinstance(result, dict)
+            and (_retrieval_score(result) or 0.0) >= self._settings.ragcore_min_search_score
+            and (source := self._managed_source(result.get("citation"), language)) is not None
         ]
         sources = _rank_sources_for_concepts(_deduplicate_sources(qualified_sources), concepts)
         if not all_sources:
@@ -424,15 +544,17 @@ class RAGcoreKnowledgeProvider:
                 correlation_id=correlation_id,
             )
 
-        damage_evidence = any(
-            term
-            in (
-                f"{source.document_id} {source.title} {source.section} {source.excerpt}"
-            ).casefold()
+        required_concepts = concepts & _ANSWERABLE_INTENT_CONCEPTS
+        evidence_text = " ".join(
+            f"{source.document_id} {source.title} {source.section} {source.excerpt}"
             for source in sources
-            for term in _DOMAIN_CONCEPTS["damage"]
-        )
-        if not concepts or not sources or ("damage" in concepts and not damage_evidence):
+        ).casefold()
+        covered_concepts = {
+            concept
+            for concept in required_concepts
+            if any(term in evidence_text for term in _DOMAIN_CONCEPTS[concept])
+        }
+        if not required_concepts or not sources or covered_concepts != required_concepts:
             KNOWLEDGE_PROVIDER_REQUESTS.labels("search", "insufficient").inc()
             return GroundedAnswer(
                 answer="",

backend/app/services/returns.py

@@ -4,7 +4,7 @@ import hashlib
 import json
 import uuid
 from dataclasses import dataclass
-from datetime import UTC, datetime, timedelta
+from datetime import UTC, datetime
 
 from sqlalchemy import select
 from sqlalchemy.exc import IntegrityError
@@ -12,13 +12,13 @@ from sqlalchemy.orm import Session
 
 from app.core.errors import AppError
 from app.models.booking import Booking
-from app.models.data_quality import DataQualityIssue
 from app.models.idempotency import IdempotencyRecord
 from app.models.inspection import Inspection
 from app.models.outbox import OutboxEvent
 from app.models.vehicle import Vehicle
 from app.schemas import CurrentUser, RegisterReturnRequest
 from app.services.audit import record_audit_event
+from app.services.data_quality import open_odometer_regression_issue
 
 
 def _new_inspection_ref() -> str:
@@ -261,28 +261,21 @@ def register_vehicle_return(
 
     quality_issue_ref: str | None = None
     if evaluation.odometer_regression:
-        issue = DataQualityIssue(
-            public_ref=f"DQ-RET-{str(inspection.public_ref).split('-')[-1]}",
-            rule_type="odometer_regression",
-            entity_type="vehicle",
-            entity_id=vehicle.id,
-            severity="medium",
-            status="open",
-            evidence_json={
-                "summary": (
-                    f"Return submitted {body.end_odometer_km} km, below canonical "
-                    f"{evaluation.canonical_odometer_km} km."
-                ),
-                "entity_ref": vehicle.public_ref,
-                "related_refs": [booking.public_ref, inspection.public_ref],
-            },
-            proposed_action_json={},
+        issue = open_odometer_regression_issue(
+            db,
+            vehicle=vehicle,
+            reading_ref=inspection.public_ref,
+            reading_km=body.end_odometer_km,
+            canonical_km=evaluation.canonical_odometer_km,
+            source_type="return",
+            related_refs=[booking.public_ref, inspection.public_ref],
+            correctable_booking_refs=[booking.public_ref],
             detected_at=now,
-            due_at=now + timedelta(days=1),
+            public_ref=f"DQ-RET-{str(inspection.public_ref).split('-')[-1]}",
+            actor_label=actor.display_name,
+            correlation_id=correlation_id,
         )
-        db.add(issue)
-        db.flush()
-        quality_issue_ref = issue.public_ref
+        quality_issue_ref = issue.public_ref if issue is not None else None
 
     resulting_status = evaluation.resulting_vehicle_status
     vehicle.odometer_km = evaluation.resulting_odometer_km

backend/tests/test_auth.py

@@ -1,3 +1,15 @@
+import threading
+
+import pytest
+from sqlalchemy import delete, func, select
+
+from app.core.db import SessionLocal, engine
+from app.models.audit import AuditEvent
+from app.models.vehicle import Vehicle
+from app.seed_loader import reset_and_seed
+from app.services.audit import record_audit_event
+
+
 def test_unauthenticated_dashboard_is_rejected(client):
     response = client.get("/api/v1/dashboard")
     assert response.status_code == 401
@@ -101,15 +113,106 @@ def test_demo_reset_rejects_concurrent_rebuild(ops_client):
     assert response.status_code == 409
 
 
+def test_demo_reset_database_lock_blocks_another_api_replica(ops_client):
+    import app.api.routers.demo as demo_router
+
+    # Use a raw connection: an ordinary Session intentionally participates in the
+    # shared mutation barrier and would make an exclusive reset wait before it can test
+    # this separate non-blocking replica lock.
+    with engine.connect() as lock_connection:
+        lock_connection.scalar(select(func.pg_advisory_lock(demo_router._RESET_ADVISORY_LOCK_ID)))
+        try:
+            response = ops_client.post("/api/v1/demo/reset")
+        finally:
+            lock_connection.scalar(
+                select(func.pg_advisory_unlock(demo_router._RESET_ADVISORY_LOCK_ID))
+            )
+    assert response.status_code == 409
+
+
+def test_demo_reset_waits_for_active_mutation_and_then_replaces_it_atomically():
+    started = threading.Event()
+    completed = threading.Event()
+    errors: list[BaseException] = []
+
+    def reset_in_other_session() -> None:
+        started.set()
+        try:
+            with SessionLocal() as reset_db:
+                reset_and_seed(reset_db)
+        except BaseException as exc:  # pragma: no cover - assertion reports thread failures
+            errors.append(exc)
+        finally:
+            completed.set()
+
+    with SessionLocal() as mutation_db:
+        vehicle = mutation_db.scalar(
+            select(Vehicle).where(Vehicle.public_ref == "MO-001").with_for_update()
+        )
+        vehicle.location = "Concurrent mutation marker"
+        mutation_db.flush()
+        worker = threading.Thread(target=reset_in_other_session, daemon=True)
+        worker.start()
+        assert started.wait(timeout=1)
+        assert not completed.wait(timeout=0.2)
+        mutation_db.commit()
+
+    worker.join(timeout=10)
+    assert not worker.is_alive(), "reset deadlocked behind the active mutation"
+    assert errors == []
+    with SessionLocal() as db:
+        restored = db.scalar(select(Vehicle).where(Vehicle.public_ref == "MO-001"))
+        assert restored.location != "Concurrent mutation marker"
+
+
 def test_demo_reset_cooldown_returns_retry_after(ops_client, monkeypatch):
     import app.api.routers.demo as demo_router
 
     monkeypatch.setattr(demo_router.settings, "demo_reset_cooldown_seconds", 60)
-    monkeypatch.setattr(demo_router, "_last_reset_monotonic", demo_router.time.monotonic())
+    with SessionLocal() as db:
+        cooldown_event = record_audit_event(
+            db,
+            actor_type="user",
+            actor_label="Cooldown test",
+            action="demo_reset",
+            entity_type="system",
+        )
+        db.commit()
+        cooldown_event_id = cooldown_event.id
     response = ops_client.post("/api/v1/demo/reset")
     assert response.status_code == 429
     assert int(response.headers["retry-after"]) >= 1
-    monkeypatch.setattr(demo_router, "_last_reset_monotonic", 0.0)
+    with SessionLocal() as db:
+        db.execute(delete(AuditEvent).where(AuditEvent.id == cooldown_event_id))
+        db.commit()
+
+
+def test_demo_reset_rolls_back_every_change_when_integrity_check_fails(ops_client, monkeypatch):
+    import app.api.routers.demo as demo_router
+
+    monkeypatch.setattr(demo_router.settings, "demo_reset_cooldown_seconds", 0)
+    with SessionLocal() as db:
+        probe = record_audit_event(
+            db,
+            actor_type="system",
+            actor_label="Atomic reset test",
+            action="reset_atomicity_probe",
+            entity_type="system",
+        )
+        db.commit()
+        probe_id = probe.id
+
+    def fail_integrity_check(_db):
+        raise RuntimeError("Injected integrity-check failure")
+
+    monkeypatch.setattr(demo_router, "scenario_integrity_report", fail_integrity_check)
+    with pytest.raises(RuntimeError, match="Injected integrity-check failure"):
+        ops_client.post("/api/v1/demo/reset")
+
+    with SessionLocal() as db:
+        assert db.scalar(select(AuditEvent).where(AuditEvent.id == probe_id)) is not None
+        db.execute(delete(AuditEvent).where(AuditEvent.id == probe_id))
+        db.commit()
 
 
 def test_reset_is_rejected_when_demo_allow_reset_is_disabled(ops_client, monkeypatch):

backend/tests/test_bookings.py

@@ -95,6 +95,16 @@ def test_booking_requirements_are_explicit_and_audited(ops_client):
     )
     assert checkout.status_code == 409
 
+    whitespace_only = ops_client.post(
+        f"/api/v1/bookings/{booking['public_ref']}/complete-requirements",
+        json={"confirmation": "   "},
+    )
+    assert whitespace_only.status_code == 422
+    assert (
+        ops_client.get(f"/api/v1/bookings/{booking['public_ref']}").json()["requirements_complete"]
+        is False
+    )
+
     confirmed = ops_client.post(
         f"/api/v1/bookings/{booking['public_ref']}/complete-requirements",
         json={"confirmation": "Licence and rental conditions checked"},
@@ -106,6 +116,29 @@ def test_booking_requirements_are_explicit_and_audited(ops_client):
     assert any(item["entity_ref"] == booking["public_ref"] for item in audit.json())
 
 
+def test_booking_creation_cannot_preconfirm_requirements(ops_client):
+    window = {"starts_at": "2033-09-01T10:00:00Z", "ends_at": "2033-09-02T12:00:00Z"}
+    vehicle = ops_client.get("/api/v1/bookings/availability", params=window).json()[0]
+
+    created = ops_client.post(
+        "/api/v1/bookings",
+        json={
+            "customer_ref": "CUS-0001",
+            "vehicle_ref": vehicle["public_ref"],
+            "requirements_complete": True,
+            **window,
+        },
+    )
+
+    assert created.status_code == 201
+    assert created.json()["requirements_complete"] is False
+    audit = ops_client.get(
+        "/api/v1/audit",
+        params={"action": "booking_requirements_completed"},
+    )
+    assert all(item["entity_ref"] != created.json()["public_ref"] for item in audit.json())
+
+
 def test_customer_search_returns_canonical_customers(ops_client):
     response = ops_client.get("/api/v1/customers", params={"query": "CUS-"})
     assert response.status_code == 200
@@ -221,10 +254,14 @@ def test_checkout_records_inspection_and_activates_safe_booking(ops_client):
         json={
             "customer_ref": "CUS-0001",
             "vehicle_ref": vehicle["public_ref"],
-            "requirements_complete": True,
             **window,
         },
     ).json()
+    confirmed = ops_client.post(
+        f"/api/v1/bookings/{booking['public_ref']}/complete-requirements",
+        json={"confirmation": "Licence and rental conditions checked"},
+    )
+    assert confirmed.status_code == 200
     response = ops_client.post(
         f"/api/v1/bookings/{booking['public_ref']}/checkout",
         json={
@@ -241,6 +278,95 @@ def test_checkout_records_inspection_and_activates_safe_booking(ops_client):
     updated_vehicle = ops_client.get(f"/api/v1/vehicles/{vehicle['public_ref']}").json()
     assert updated_vehicle["operational_status"] == "rented"
     assert any(item["type"] == "checkout" for item in updated_vehicle["inspections"])
+    checkout_audit = ops_client.get(
+        "/api/v1/audit",
+        params={"action": "booking_checkout_recorded"},
+    ).json()
+    booking_event = next(
+        item for item in checkout_audit if item["entity_ref"] == booking["public_ref"]
+    )
+    vehicle_audit = ops_client.get(
+        "/api/v1/audit",
+        params={
+            "action": "vehicle_status_changed",
+            "correlation_id": booking_event["correlation_id"],
+        },
+    ).json()
+    assert len(vehicle_audit) == 1
+    assert vehicle_audit[0]["entity_ref"] == vehicle["public_ref"]
+    assert vehicle_audit[0]["before"]["operational_status"] == "available"
+    assert vehicle_audit[0]["after"]["operational_status"] == "rented"
+
+
+def test_checkout_odometer_regression_keeps_canonical_and_opens_bounded_quality_issue(
+    ops_client,
+):
+    window = {"starts_at": "2052-09-01T10:00:00Z", "ends_at": "2052-09-02T12:00:00Z"}
+    existing_issues = ops_client.get(
+        "/api/v1/data-quality/issues",
+        params={"status": "open", "rule_type": "odometer_regression"},
+    ).json()
+    unavailable_refs = {issue["entity_ref"] for issue in existing_issues}
+    available = ops_client.get("/api/v1/bookings/availability", params=window).json()
+    vehicle_option = next(
+        item
+        for item in available
+        if item["operational_status"] == "available" and item["public_ref"] not in unavailable_refs
+    )
+    vehicle = ops_client.get(f"/api/v1/vehicles/{vehicle_option['public_ref']}").json()
+    assert vehicle["odometer_km"] > 0
+    booking = ops_client.post(
+        "/api/v1/bookings",
+        json={
+            "customer_ref": "CUS-0003",
+            "vehicle_ref": vehicle["public_ref"],
+            **window,
+        },
+    ).json()
+    ops_client.post(
+        f"/api/v1/bookings/{booking['public_ref']}/complete-requirements",
+        json={"confirmation": "Licence and rental conditions checked"},
+    )
+
+    checkout = ops_client.post(
+        f"/api/v1/bookings/{booking['public_ref']}/checkout",
+        json={
+            "start_odometer_km": vehicle["odometer_km"] - 1,
+            "fuel_level_percent": 90,
+            "cleanliness_ok": True,
+            "damage_reported": False,
+            "technical_warning": False,
+        },
+    )
+
+    assert checkout.status_code == 200
+    assert checkout.json()["booking_status"] == "blocked"
+    updated_vehicle = ops_client.get(f"/api/v1/vehicles/{vehicle['public_ref']}").json()
+    assert updated_vehicle["odometer_km"] == vehicle["odometer_km"]
+    issues = ops_client.get(
+        "/api/v1/data-quality/issues",
+        params={"status": "open", "rule_type": "odometer_regression"},
+    ).json()
+    issue = next(item for item in issues if item["entity_ref"] == vehicle["public_ref"])
+    assert issue["evidence"]["source_type"] == "checkout"
+    assert issue["evidence"]["correctable_booking_refs"] == []
+    detail = ops_client.get(f"/api/v1/data-quality/issues/{issue['public_ref']}").json()
+    assert any(snapshot["entity_type"] == "inspection" for snapshot in detail["related_snapshots"])
+    invalid_correction = ops_client.post(
+        f"/api/v1/data-quality/issues/{issue['public_ref']}/resolve-odometer-regression",
+        json={
+            "decision": "correct_reading",
+            "booking_ref": booking["public_ref"],
+            "corrected_odometer_km": vehicle["odometer_km"],
+        },
+    )
+    assert invalid_correction.status_code == 422
+    retained = ops_client.post(
+        f"/api/v1/data-quality/issues/{issue['public_ref']}/resolve-odometer-regression",
+        json={"decision": "retain_canonical"},
+    )
+    assert retained.status_code == 200
+    assert retained.json()["status"] == "resolved"
 
 
 def test_get_booking_detail(ops_client):

backend/tests/test_dashboard.py

@@ -1,3 +1,9 @@
+from sqlalchemy import select
+
+from app.core.db import SessionLocal
+from app.models.vehicle import Vehicle
+
+
 def test_dashboard_metrics_are_persisted_counts(ops_client):
     response = ops_client.get("/api/v1/dashboard")
     assert response.status_code == 200
@@ -15,6 +21,43 @@ def test_dashboard_metrics_are_persisted_counts(ops_client):
     assert metrics["pending_or_failed_workflows"] >= 1
 
 
+def test_dashboard_metrics_change_when_persisted_fleet_data_changes(ops_client):
+    before = ops_client.get("/api/v1/dashboard").json()["metrics"]
+    db = SessionLocal()
+    probe = Vehicle(
+        public_ref="MO-METRIC-PROBE",
+        make="Synthetic",
+        model="Metric probe",
+        model_year=2026,
+        registration_number="TEST-METRIC-PROBE",
+        location="Test fixture",
+        operational_status="blocked",
+        odometer_km=0,
+        next_service_km=1,
+        active=True,
+        version=1,
+    )
+    try:
+        db.add(probe)
+        db.commit()
+
+        after_response = ops_client.get("/api/v1/dashboard")
+        assert after_response.status_code == 200
+        after = after_response.json()["metrics"]
+        assert after["blocked"] == before["blocked"] + 1
+        fleet_statuses = ("available", "rented", "cleaning", "maintenance", "blocked")
+        assert (
+            sum(after[status] for status in fleet_statuses)
+            == sum(before[status] for status in fleet_statuses) + 1
+        )
+    finally:
+        persisted_probe = db.scalar(select(Vehicle).where(Vehicle.public_ref == "MO-METRIC-PROBE"))
+        if persisted_probe is not None:
+            db.delete(persisted_probe)
+            db.commit()
+        db.close()
+
+
 def test_dashboard_attention_items_link_to_records(ops_client):
     response = ops_client.get("/api/v1/dashboard")
     body = response.json()

backend/tests/test_data_quality.py

@@ -1,8 +1,25 @@
-from sqlalchemy import select
+from concurrent.futures import ThreadPoolExecutor
+from datetime import UTC, datetime, timedelta
+from threading import Barrier
+
+from sqlalchemy import delete, select, text
 
 from app.core.db import SessionLocal
+from app.models.audit import AuditEvent
 from app.models.booking import Booking
+from app.models.customer import Customer
+from app.models.data_quality import DataQualityIssue
+from app.models.idempotency import IdempotencyRecord
+from app.models.inspection import Inspection
+from app.models.maintenance import MaintenanceRecord
+from app.models.outbox import OutboxEvent
 from app.models.vehicle import Vehicle
+from app.schemas import CurrentUser, RegisterReturnRequest, ResolveOdometerRegressionRequest
+from app.services.data_quality import (
+    open_odometer_regression_issue,
+    resolve_odometer_regression,
+)
+from app.services.returns import register_vehicle_return
 
 
 def _activate_booking(vehicle_ref: str, start_odometer_km: int) -> str:
@@ -21,6 +38,30 @@ def _activate_booking(vehicle_ref: str, start_odometer_km: int) -> str:
         db.close()
 
 
+def _cleanup_odometer_scenario(vehicle_id, customer_id) -> None:
+    """Remove one isolated DQ-03 scenario in foreign-key-safe order."""
+    with SessionLocal() as db:
+        booking_ids = db.scalars(select(Booking.id).where(Booking.vehicle_id == vehicle_id)).all()
+        issue_ids = db.scalars(
+            select(DataQualityIssue.id).where(DataQualityIssue.entity_id == vehicle_id)
+        ).all()
+        audit_entity_ids = [vehicle_id, *booking_ids, *issue_ids]
+        if audit_entity_ids:
+            db.execute(delete(AuditEvent).where(AuditEvent.entity_id.in_(audit_entity_ids)))
+        if booking_ids:
+            db.execute(
+                delete(IdempotencyRecord).where(IdempotencyRecord.booking_id.in_(booking_ids))
+            )
+            db.execute(delete(OutboxEvent).where(OutboxEvent.aggregate_id.in_(booking_ids)))
+        db.execute(delete(DataQualityIssue).where(DataQualityIssue.entity_id == vehicle_id))
+        db.execute(delete(Inspection).where(Inspection.vehicle_id == vehicle_id))
+        db.execute(delete(MaintenanceRecord).where(MaintenanceRecord.vehicle_id == vehicle_id))
+        db.execute(delete(Booking).where(Booking.vehicle_id == vehicle_id))
+        db.execute(delete(Vehicle).where(Vehicle.id == vehicle_id))
+        db.execute(delete(Customer).where(Customer.id == customer_id))
+        db.commit()
+
+
 def test_list_includes_all_five_rule_types(ops_client):
     response = ops_client.get("/api/v1/data-quality/issues")
     assert response.status_code == 200
@@ -43,6 +84,84 @@ def test_scan_is_idempotent_once_seeded(ops_client):
     assert response.json()["created"] == {}
 
 
+def test_scan_detects_imported_maintenance_odometer_regression(ops_client):
+    with SessionLocal() as db:
+        vehicle = Vehicle(
+            public_ref="MO-DQ-SCAN",
+            make="Synthetic",
+            model="Scanner",
+            model_year=2026,
+            registration_number="DQ-SCAN-01",
+            location="Brussels",
+            operational_status="available",
+            odometer_km=20_000,
+            next_service_km=30_000,
+            active=True,
+            version=1,
+        )
+        db.add(vehicle)
+        db.flush()
+        vehicle_id = vehicle.id
+        db.add_all(
+            [
+                MaintenanceRecord(
+                    public_ref="MAINT-DQ-SCAN-A",
+                    vehicle_id=vehicle.id,
+                    occurred_at=datetime(2045, 1, 1, tzinfo=UTC),
+                    odometer_km=20_000,
+                    category="inspection",
+                    summary="Synthetic scan baseline",
+                ),
+                MaintenanceRecord(
+                    public_ref="MAINT-DQ-SCAN-B",
+                    vehicle_id=vehicle.id,
+                    occurred_at=datetime(2045, 2, 1, tzinfo=UTC),
+                    odometer_km=19_000,
+                    category="inspection",
+                    summary="Synthetic imported regression",
+                ),
+            ]
+        )
+        db.commit()
+    try:
+        response = ops_client.post("/api/v1/data-quality/scan")
+        assert response.status_code == 200
+        assert response.json()["created"]["odometer_regression"] >= 1
+        issues = ops_client.get(
+            "/api/v1/data-quality/issues",
+            params={"status": "open", "rule_type": "odometer_regression"},
+        ).json()
+        issue = next(item for item in issues if item["entity_ref"] == "MO-DQ-SCAN")
+        assert issue["evidence"]["source_type"] == "maintenance"
+        assert issue["evidence"]["correctable_booking_refs"] == []
+
+        # A later imported regression must enrich the existing open issue instead of
+        # being silently dropped by the generic check-then-return scanner path.
+        with SessionLocal() as db:
+            db.add(
+                MaintenanceRecord(
+                    public_ref="MAINT-DQ-SCAN-C",
+                    vehicle_id=vehicle_id,
+                    occurred_at=datetime(2045, 3, 1, tzinfo=UTC),
+                    odometer_km=18_000,
+                    category="inspection",
+                    summary="Second synthetic imported regression",
+                )
+            )
+            db.commit()
+        rescanned = ops_client.post("/api/v1/data-quality/scan")
+        assert rescanned.status_code == 200
+        enriched = ops_client.get(f"/api/v1/data-quality/issues/{issue['public_ref']}").json()
+        later_refs = {signal["params"]["later_ref"] for signal in enriched["evidence"]["signals"]}
+        assert {"MAINT-DQ-SCAN-B", "MAINT-DQ-SCAN-C"}.issubset(later_refs)
+    finally:
+        with SessionLocal() as db:
+            db.execute(delete(DataQualityIssue).where(DataQualityIssue.entity_id == vehicle_id))
+            db.execute(delete(MaintenanceRecord).where(MaintenanceRecord.vehicle_id == vehicle_id))
+            db.execute(delete(Vehicle).where(Vehicle.id == vehicle_id))
+            db.commit()
+
+
 def test_scan_requires_operations_manager(employee_client):
     response = employee_client.post("/api/v1/data-quality/scan")
     assert response.status_code == 403
@@ -440,9 +559,8 @@ def test_resolve_odometer_regression_correction_below_canonical_is_rejected_then
 
 
 def test_resolve_odometer_regression_correct_reading_updates_canonical(ops_client):
-    # The seeded odometer_regression issues carry no related booking (CSV-only rows).
-    # Create a fresh one with a real related booking via a live regression return, so
-    # the "correct_reading" path has an actual booking_ref to target.
+    # Create a live return regression to prove the complete correction chain updates
+    # both persisted representations of that reading (booking + return inspection).
     booking_ref = _activate_booking("MO-018", start_odometer_km=12000)
     vehicle_before = ops_client.get("/api/v1/vehicles/MO-018").json()
     low_reading = vehicle_before["odometer_km"] - 200
@@ -459,6 +577,7 @@ def test_resolve_odometer_regression_correct_reading_updates_canonical(ops_clien
     )
     assert returned.status_code == 201
     issue_ref = returned.json()["quality_issue_ref"]
+    inspection_ref = returned.json()["inspection_ref"]
     assert issue_ref is not None
 
     corrected = vehicle_before["odometer_km"] + 500
@@ -477,6 +596,701 @@ def test_resolve_odometer_regression_correct_reading_updates_canonical(ops_clien
     assert vehicle["odometer_km"] == corrected
     booking = ops_client.get(f"/api/v1/bookings/{booking_ref}").json()
     assert booking["end_odometer_km"] == corrected
+    with SessionLocal() as db:
+        inspection = db.scalar(select(Inspection).where(Inspection.public_ref == inspection_ref))
+        assert inspection is not None
+        assert inspection.odometer_km == corrected
+
+
+def test_correcting_one_of_two_regressions_keeps_the_other_open(ops_client):
+    with SessionLocal() as db:
+        customer = Customer(
+            public_ref="CUS-DQ-MULTI",
+            first_name="Synthetic",
+            last_name="Multi",
+            email="dq-multi@example.test",
+        )
+        vehicle = Vehicle(
+            public_ref="MO-DQ-MULTI",
+            make="Synthetic",
+            model="Multi",
+            model_year=2026,
+            registration_number="DQ-MULTI",
+            location="Brussels",
+            operational_status="available",
+            odometer_km=1_000,
+            next_service_km=2_000,
+            active=True,
+            version=1,
+        )
+        db.add_all([customer, vehicle])
+        db.flush()
+        bookings: list[Booking] = []
+        inspections: list[Inspection] = []
+        for index, reading in enumerate((900, 800), start=1):
+            booking = Booking(
+                public_ref=f"BK-DQ-MULTI-{index}",
+                customer_id=customer.id,
+                vehicle_id=vehicle.id,
+                starts_at=datetime(2046, index, 1, tzinfo=UTC),
+                ends_at=datetime(2046, index, 2, tzinfo=UTC),
+                status="returned",
+                start_odometer_km=reading - 10,
+                end_odometer_km=reading,
+                requirements_complete=True,
+            )
+            db.add(booking)
+            db.flush()
+            inspection = Inspection(
+                public_ref=f"INSP-DQ-M-{index}",
+                booking_id=booking.id,
+                vehicle_id=vehicle.id,
+                type="return",
+                fuel_level_percent=50,
+                cleanliness_ok=True,
+                damage_reported=False,
+                technical_warning=False,
+                odometer_km=reading,
+                completed_at=booking.ends_at,
+            )
+            db.add(inspection)
+            db.flush()
+            open_odometer_regression_issue(
+                db,
+                vehicle=vehicle,
+                reading_ref=inspection.public_ref,
+                reading_km=reading,
+                canonical_km=vehicle.odometer_km,
+                source_type="return",
+                related_refs=[booking.public_ref, inspection.public_ref],
+                correctable_booking_refs=[booking.public_ref],
+                public_ref="DQ-MULTI-SOURCE" if index == 1 else None,
+            )
+            bookings.append(booking)
+            inspections.append(inspection)
+        booking_refs = [booking.public_ref for booking in bookings]
+        vehicle_id = vehicle.id
+        customer_id = customer.id
+        db.commit()
+
+    try:
+        first = ops_client.post(
+            "/api/v1/data-quality/issues/DQ-MULTI-SOURCE/resolve-odometer-regression",
+            json={
+                "decision": "correct_reading",
+                "booking_ref": booking_refs[0],
+                "corrected_odometer_km": 1_100,
+            },
+        )
+        assert first.status_code == 200, first.text
+        assert first.json()["status"] == "open"
+        assert first.json()["evidence"]["correctable_booking_refs"] == [booking_refs[1]]
+
+        second = ops_client.post(
+            "/api/v1/data-quality/issues/DQ-MULTI-SOURCE/resolve-odometer-regression",
+            json={
+                "decision": "correct_reading",
+                "booking_ref": booking_refs[1],
+                "corrected_odometer_km": 1_200,
+            },
+        )
+        assert second.status_code == 200, second.text
+        assert second.json()["status"] == "resolved"
+        with SessionLocal() as db:
+            persisted = db.scalars(
+                select(Inspection)
+                .where(Inspection.vehicle_id == vehicle_id)
+                .order_by(Inspection.public_ref)
+            ).all()
+            assert [item.odometer_km for item in persisted] == [1_100, 1_200]
+    finally:
+        with SessionLocal() as db:
+            db.execute(delete(DataQualityIssue).where(DataQualityIssue.entity_id == vehicle_id))
+            db.execute(delete(Inspection).where(Inspection.vehicle_id == vehicle_id))
+            db.execute(delete(Booking).where(Booking.vehicle_id == vehicle_id))
+            db.execute(delete(Vehicle).where(Vehicle.id == vehicle_id))
+            db.execute(delete(Customer).where(Customer.id == customer_id))
+            db.commit()
+
+
+def test_retained_regression_is_suppressed_until_source_reading_changes(ops_client):
+    with SessionLocal() as db:
+        vehicle = Vehicle(
+            public_ref="MO-DQ-RETAIN",
+            make="Synthetic",
+            model="Retain",
+            model_year=2026,
+            registration_number="DQ-RETAIN",
+            location="Brussels",
+            operational_status="available",
+            odometer_km=20_000,
+            next_service_km=30_000,
+            active=True,
+            version=1,
+        )
+        db.add(vehicle)
+        db.flush()
+        vehicle_id = vehicle.id
+        db.add_all(
+            [
+                MaintenanceRecord(
+                    public_ref="MAINT-DQ-RET-A",
+                    vehicle_id=vehicle.id,
+                    occurred_at=datetime(2047, 1, 1, tzinfo=UTC),
+                    odometer_km=20_000,
+                    category="inspection",
+                    summary="Retain baseline",
+                ),
+                MaintenanceRecord(
+                    public_ref="MAINT-DQ-RET-B",
+                    vehicle_id=vehicle.id,
+                    occurred_at=datetime(2047, 2, 1, tzinfo=UTC),
+                    odometer_km=19_000,
+                    category="inspection",
+                    summary="Retained source reading",
+                ),
+            ]
+        )
+        db.commit()
+    try:
+        assert ops_client.post("/api/v1/data-quality/scan").status_code == 200
+        issue = next(
+            item
+            for item in ops_client.get(
+                "/api/v1/data-quality/issues",
+                params={"status": "open", "rule_type": "odometer_regression"},
+            ).json()
+            if item["entity_ref"] == "MO-DQ-RETAIN"
+        )
+        retained = ops_client.post(
+            f"/api/v1/data-quality/issues/{issue['public_ref']}/resolve-odometer-regression",
+            json={"decision": "retain_canonical", "note": "Verified source entry"},
+        )
+        assert retained.status_code == 200
+        assert retained.json()["status"] == "resolved"
+
+        assert ops_client.post("/api/v1/data-quality/scan").status_code == 200
+        with SessionLocal() as db:
+            assert (
+                db.scalar(
+                    select(DataQualityIssue).where(
+                        DataQualityIssue.entity_id == vehicle_id,
+                        DataQualityIssue.status == "open",
+                    )
+                )
+                is None
+            )
+            changed = db.scalar(
+                select(MaintenanceRecord).where(MaintenanceRecord.public_ref == "MAINT-DQ-RET-B")
+            )
+            changed.odometer_km = 18_999
+            db.commit()
+
+        assert ops_client.post("/api/v1/data-quality/scan").status_code == 200
+        reopened = next(
+            item
+            for item in ops_client.get(
+                "/api/v1/data-quality/issues",
+                params={"status": "open", "rule_type": "odometer_regression"},
+            ).json()
+            if item["entity_ref"] == "MO-DQ-RETAIN"
+        )
+        assert reopened["evidence"]["reopened_from"] == issue["public_ref"]
+    finally:
+        with SessionLocal() as db:
+            db.execute(delete(DataQualityIssue).where(DataQualityIssue.entity_id == vehicle_id))
+            db.execute(delete(MaintenanceRecord).where(MaintenanceRecord.vehicle_id == vehicle_id))
+            db.execute(delete(Vehicle).where(Vehicle.id == vehicle_id))
+            db.commit()
+
+
+def test_live_return_retained_as_canonical_is_not_reopened_by_scan(ops_client):
+    now = datetime.now(UTC)
+    with SessionLocal() as db:
+        customer = Customer(
+            public_ref="CUS-DQ-LIVE-RET",
+            first_name="Synthetic",
+            last_name="Retained return",
+            email="dq-live-retain@example.test",
+        )
+        vehicle = Vehicle(
+            public_ref="MO-DQ-LIVE-RET",
+            make="Synthetic",
+            model="Retained return",
+            model_year=2026,
+            registration_number="DQ-LIVE-RET",
+            location="Brussels",
+            operational_status="rented",
+            odometer_km=20_000,
+            next_service_km=30_000,
+            active=True,
+            version=1,
+        )
+        db.add_all([customer, vehicle])
+        db.flush()
+        booking = Booking(
+            public_ref="BK-DQ-LIVE-RET",
+            customer_id=customer.id,
+            vehicle_id=vehicle.id,
+            starts_at=now - timedelta(days=2),
+            ends_at=now + timedelta(days=1),
+            status="active",
+            start_odometer_km=19_500,
+            end_odometer_km=None,
+            requirements_complete=True,
+        )
+        db.add_all(
+            [
+                booking,
+                MaintenanceRecord(
+                    public_ref="MNT-DQ-LIVE-RET",
+                    vehicle_id=vehicle.id,
+                    occurred_at=now - timedelta(days=3),
+                    odometer_km=20_000,
+                    category="inspection",
+                    summary="Synthetic canonical baseline",
+                ),
+            ]
+        )
+        vehicle_id = vehicle.id
+        customer_id = customer.id
+        db.commit()
+
+    try:
+        returned = ops_client.post(
+            "/api/v1/bookings/BK-DQ-LIVE-RET/return",
+            json={
+                "end_odometer_km": 19_000,
+                "fuel_level_percent": 50,
+                "cleanliness_ok": True,
+                "damage_reported": False,
+                "technical_warning": False,
+            },
+            headers={"Idempotency-Key": "test-dq-live-retain-001"},
+        )
+        assert returned.status_code == 201, returned.text
+        issue_ref = returned.json()["quality_issue_ref"]
+        inspection_ref = returned.json()["inspection_ref"]
+        assert issue_ref is not None
+
+        retained = ops_client.post(
+            f"/api/v1/data-quality/issues/{issue_ref}/resolve-odometer-regression",
+            json={"decision": "retain_canonical", "note": "Source reading verified as wrong."},
+        )
+        assert retained.status_code == 200, retained.text
+        assert retained.json()["status"] == "resolved"
+        assert retained.json()["evidence"]["retained_odometer_fingerprints"] == [
+            {
+                "source_type": "return",
+                "later_ref": inspection_ref,
+                "later_km": 19_000,
+            }
+        ]
+
+        scanned = ops_client.post("/api/v1/data-quality/scan")
+        assert scanned.status_code == 200, scanned.text
+        with SessionLocal() as db:
+            issues = db.scalars(
+                select(DataQualityIssue)
+                .where(
+                    DataQualityIssue.entity_id == vehicle_id,
+                    DataQualityIssue.rule_type == "odometer_regression",
+                )
+                .order_by(DataQualityIssue.detected_at)
+            ).all()
+            assert [(issue.public_ref, issue.status) for issue in issues] == [
+                (issue_ref, "resolved")
+            ]
+    finally:
+        _cleanup_odometer_scenario(vehicle_id, customer_id)
+
+
+def test_scanned_return_regression_can_correct_booking_all_inspections_and_vehicle(ops_client):
+    now = datetime.now(UTC)
+    with SessionLocal() as db:
+        customer = Customer(
+            public_ref="CUS-DQ-SCAN-RET",
+            first_name="Synthetic",
+            last_name="Scanned return",
+            email="dq-scan-return@example.test",
+        )
+        vehicle = Vehicle(
+            public_ref="MO-DQ-SCAN-RET",
+            make="Synthetic",
+            model="Scanned return",
+            model_year=2026,
+            registration_number="DQ-SCAN-RET",
+            location="Brussels",
+            operational_status="available",
+            odometer_km=20_000,
+            next_service_km=30_000,
+            active=True,
+            version=1,
+        )
+        db.add_all([customer, vehicle])
+        db.flush()
+        booking = Booking(
+            public_ref="BK-DQ-SCAN-RET",
+            customer_id=customer.id,
+            vehicle_id=vehicle.id,
+            starts_at=now - timedelta(days=3),
+            ends_at=now - timedelta(hours=12),
+            status="returned",
+            start_odometer_km=19_500,
+            end_odometer_km=18_500,
+            requirements_complete=True,
+        )
+        db.add(booking)
+        db.flush()
+        db.add_all(
+            [
+                MaintenanceRecord(
+                    public_ref="MNT-DQ-SCAN-RET",
+                    vehicle_id=vehicle.id,
+                    occurred_at=now - timedelta(days=4),
+                    odometer_km=20_000,
+                    category="inspection",
+                    summary="Synthetic canonical baseline",
+                ),
+                Inspection(
+                    public_ref="INSP-DQ-SCAN-R1",
+                    booking_id=booking.id,
+                    vehicle_id=vehicle.id,
+                    type="return",
+                    fuel_level_percent=50,
+                    cleanliness_ok=True,
+                    damage_reported=False,
+                    technical_warning=False,
+                    odometer_km=19_000,
+                    completed_at=now - timedelta(days=1),
+                ),
+                Inspection(
+                    public_ref="INSP-DQ-SCAN-R2",
+                    booking_id=booking.id,
+                    vehicle_id=vehicle.id,
+                    type="return",
+                    fuel_level_percent=50,
+                    cleanliness_ok=True,
+                    damage_reported=False,
+                    technical_warning=False,
+                    odometer_km=18_500,
+                    completed_at=now - timedelta(hours=12),
+                ),
+            ]
+        )
+        vehicle_id = vehicle.id
+        customer_id = customer.id
+        db.commit()
+
+    try:
+        scanned = ops_client.post("/api/v1/data-quality/scan")
+        assert scanned.status_code == 200, scanned.text
+        issue = next(
+            item
+            for item in ops_client.get(
+                "/api/v1/data-quality/issues",
+                params={"status": "open", "rule_type": "odometer_regression"},
+            ).json()
+            if item["entity_ref"] == "MO-DQ-SCAN-RET"
+        )
+        assert issue["evidence"]["correctable_booking_refs"] == ["BK-DQ-SCAN-RET"]
+        later_refs = {signal["params"]["later_ref"] for signal in issue["evidence"]["signals"]}
+        assert later_refs == {"INSP-DQ-SCAN-R1", "INSP-DQ-SCAN-R2"}
+
+        corrected = ops_client.post(
+            f"/api/v1/data-quality/issues/{issue['public_ref']}/resolve-odometer-regression",
+            json={
+                "decision": "correct_reading",
+                "booking_ref": "BK-DQ-SCAN-RET",
+                "corrected_odometer_km": 20_500,
+            },
+        )
+        assert corrected.status_code == 200, corrected.text
+        assert corrected.json()["status"] == "resolved"
+
+        with SessionLocal() as db:
+            persisted_vehicle = db.get(Vehicle, vehicle_id)
+            persisted_booking = db.scalar(
+                select(Booking).where(Booking.public_ref == "BK-DQ-SCAN-RET")
+            )
+            assert persisted_booking is not None
+            persisted_inspections = db.scalars(
+                select(Inspection)
+                .where(Inspection.booking_id == persisted_booking.id, Inspection.type == "return")
+                .order_by(Inspection.public_ref)
+            ).all()
+            assert persisted_vehicle is not None
+            assert persisted_vehicle.odometer_km == 20_500
+            assert persisted_booking.end_odometer_km == 20_500
+            assert [inspection.odometer_km for inspection in persisted_inspections] == [
+                20_500,
+                20_500,
+            ]
+    finally:
+        _cleanup_odometer_scenario(vehicle_id, customer_id)
+
+
+def test_resolver_and_concurrent_return_finish_without_deadlock_or_lost_evidence():
+    now = datetime.now(UTC)
+    with SessionLocal() as db:
+        customer = Customer(
+            public_ref="CUS-DQ-RACE",
+            first_name="Synthetic",
+            last_name="Race",
+            email="dq-race@example.test",
+        )
+        vehicle = Vehicle(
+            public_ref="MO-DQ-RACE",
+            make="Synthetic",
+            model="Race",
+            model_year=2026,
+            registration_number="DQ-RACE",
+            location="Brussels",
+            operational_status="rented",
+            odometer_km=20_000,
+            next_service_km=30_000,
+            active=True,
+            version=1,
+        )
+        db.add_all([customer, vehicle])
+        db.flush()
+        corrected_booking = Booking(
+            public_ref="BK-DQ-RACE-OLD",
+            customer_id=customer.id,
+            vehicle_id=vehicle.id,
+            starts_at=now - timedelta(days=4),
+            ends_at=now - timedelta(days=3),
+            status="returned",
+            start_odometer_km=19_500,
+            end_odometer_km=19_000,
+            requirements_complete=True,
+        )
+        concurrent_booking = Booking(
+            public_ref="BK-DQ-RACE-NEW",
+            customer_id=customer.id,
+            vehicle_id=vehicle.id,
+            starts_at=now - timedelta(days=1),
+            ends_at=now + timedelta(days=1),
+            status="active",
+            start_odometer_km=19_000,
+            end_odometer_km=None,
+            requirements_complete=True,
+        )
+        db.add_all([corrected_booking, concurrent_booking])
+        db.flush()
+        old_inspection = Inspection(
+            public_ref="INSP-DQ-RACE-OLD",
+            booking_id=corrected_booking.id,
+            vehicle_id=vehicle.id,
+            type="return",
+            fuel_level_percent=50,
+            cleanliness_ok=True,
+            damage_reported=False,
+            technical_warning=False,
+            odometer_km=19_000,
+            completed_at=corrected_booking.ends_at,
+        )
+        db.add(old_inspection)
+        db.flush()
+        issue = open_odometer_regression_issue(
+            db,
+            vehicle=vehicle,
+            reading_ref=old_inspection.public_ref,
+            reading_km=19_000,
+            canonical_km=20_000,
+            source_type="return",
+            related_refs=[corrected_booking.public_ref, old_inspection.public_ref],
+            correctable_booking_refs=[corrected_booking.public_ref],
+            public_ref="DQ-ODO-RACE",
+        )
+        assert issue is not None
+        vehicle_id = vehicle.id
+        customer_id = customer.id
+        db.commit()
+
+    actor = CurrentUser(
+        public_ref="USR-DQ-RACE",
+        display_name="DQ Race Manager",
+        role="operations_manager",
+    )
+    start = Barrier(2)
+
+    def correct_existing_reading() -> str:
+        with SessionLocal() as db:
+            db.execute(text("SET LOCAL lock_timeout = '5s'"))
+            start.wait(timeout=5)
+            resolved = resolve_odometer_regression(
+                db,
+                "DQ-ODO-RACE",
+                ResolveOdometerRegressionRequest(
+                    decision="correct_reading",
+                    booking_ref="BK-DQ-RACE-OLD",
+                    corrected_odometer_km=20_500,
+                ),
+                actor,
+            )
+            return resolved.status
+
+    def return_other_booking() -> dict:
+        with SessionLocal() as db:
+            db.execute(text("SET LOCAL lock_timeout = '5s'"))
+            start.wait(timeout=5)
+            _status, response = register_vehicle_return(
+                db,
+                "BK-DQ-RACE-NEW",
+                RegisterReturnRequest(
+                    end_odometer_km=18_000,
+                    fuel_level_percent=50,
+                    cleanliness_ok=True,
+                    damage_reported=False,
+                    technical_warning=False,
+                ),
+                "test-dq-resolve-return-race-001",
+                actor,
+            )
+            return response
+
+    try:
+        with ThreadPoolExecutor(max_workers=2) as executor:
+            correction_future = executor.submit(correct_existing_reading)
+            return_future = executor.submit(return_other_booking)
+            correction_status = correction_future.result(timeout=15)
+            return_result = return_future.result(timeout=15)
+
+        assert correction_status in {"open", "resolved"}
+        assert return_result["quality_issue_ref"] is not None
+        with SessionLocal() as db:
+            persisted_vehicle = db.get(Vehicle, vehicle_id)
+            bookings = {
+                booking.public_ref: booking
+                for booking in db.scalars(
+                    select(Booking).where(Booking.vehicle_id == vehicle_id)
+                ).all()
+            }
+            old_inspections = db.scalars(
+                select(Inspection).where(Inspection.booking_id == bookings["BK-DQ-RACE-OLD"].id)
+            ).all()
+            open_issues = db.scalars(
+                select(DataQualityIssue).where(
+                    DataQualityIssue.entity_id == vehicle_id,
+                    DataQualityIssue.rule_type == "odometer_regression",
+                    DataQualityIssue.status == "open",
+                )
+            ).all()
+            assert persisted_vehicle is not None
+            assert persisted_vehicle.odometer_km == 20_500
+            assert bookings["BK-DQ-RACE-OLD"].end_odometer_km == 20_500
+            assert [inspection.odometer_km for inspection in old_inspections] == [20_500]
+            assert bookings["BK-DQ-RACE-NEW"].status == "returned"
+            assert bookings["BK-DQ-RACE-NEW"].end_odometer_km == 18_000
+            assert len(open_issues) == 1
+            assert open_issues[0].evidence_json["correctable_booking_refs"] == ["BK-DQ-RACE-NEW"]
+            later_refs = {
+                signal["params"]["later_ref"] for signal in open_issues[0].evidence_json["signals"]
+            }
+            assert later_refs == {return_result["inspection_ref"]}
+    finally:
+        _cleanup_odometer_scenario(vehicle_id, customer_id)
+
+
+def test_early_return_uses_inspection_time_without_duplicate_booking_regression(ops_client):
+    with SessionLocal() as db:
+        customer = Customer(
+            public_ref="CUS-DQ-EARLY",
+            first_name="Synthetic",
+            last_name="Early",
+            email="dq-early@example.test",
+        )
+        vehicle = Vehicle(
+            public_ref="MO-DQ-EARLY",
+            make="Synthetic",
+            model="Early",
+            model_year=2026,
+            registration_number="DQ-EARLY",
+            location="Brussels",
+            operational_status="available",
+            odometer_km=200,
+            next_service_km=10_000,
+            active=True,
+            version=1,
+        )
+        db.add_all([customer, vehicle])
+        db.flush()
+        early = Booking(
+            public_ref="BK-DQ-EARLY-A",
+            customer_id=customer.id,
+            vehicle_id=vehicle.id,
+            starts_at=datetime(2048, 1, 1, tzinfo=UTC),
+            ends_at=datetime(2048, 3, 1, tzinfo=UTC),
+            status="returned",
+            start_odometer_km=90,
+            end_odometer_km=100,
+            requirements_complete=True,
+        )
+        later = Booking(
+            public_ref="BK-DQ-EARLY-B",
+            customer_id=customer.id,
+            vehicle_id=vehicle.id,
+            starts_at=datetime(2048, 1, 10, tzinfo=UTC),
+            ends_at=datetime(2048, 2, 1, tzinfo=UTC),
+            status="returned",
+            start_odometer_km=100,
+            end_odometer_km=200,
+            requirements_complete=True,
+        )
+        db.add_all([early, later])
+        db.flush()
+        db.add_all(
+            [
+                Inspection(
+                    public_ref="INSP-DQ-EARLY-A",
+                    booking_id=early.id,
+                    vehicle_id=vehicle.id,
+                    type="return",
+                    fuel_level_percent=50,
+                    cleanliness_ok=True,
+                    damage_reported=False,
+                    technical_warning=False,
+                    odometer_km=100,
+                    completed_at=datetime(2048, 1, 2, tzinfo=UTC),
+                ),
+                Inspection(
+                    public_ref="INSP-DQ-EARLY-B",
+                    booking_id=later.id,
+                    vehicle_id=vehicle.id,
+                    type="return",
+                    fuel_level_percent=50,
+                    cleanliness_ok=True,
+                    damage_reported=False,
+                    technical_warning=False,
+                    odometer_km=200,
+                    completed_at=datetime(2048, 2, 1, tzinfo=UTC),
+                ),
+            ]
+        )
+        vehicle_id = vehicle.id
+        customer_id = customer.id
+        db.commit()
+    try:
+        assert ops_client.post("/api/v1/data-quality/scan").status_code == 200
+        with SessionLocal() as db:
+            assert (
+                db.scalar(
+                    select(DataQualityIssue).where(
+                        DataQualityIssue.entity_id == vehicle_id,
+                        DataQualityIssue.rule_type == "odometer_regression",
+                    )
+                )
+                is None
+            )
+    finally:
+        with SessionLocal() as db:
+            db.execute(delete(DataQualityIssue).where(DataQualityIssue.entity_id == vehicle_id))
+            db.execute(delete(Inspection).where(Inspection.vehicle_id == vehicle_id))
+            db.execute(delete(Booking).where(Booking.vehicle_id == vehicle_id))
+            db.execute(delete(Vehicle).where(Vehicle.id == vehicle_id))
+            db.execute(delete(Customer).where(Customer.id == customer_id))
+            db.commit()
 
 
 def test_manual_scan_records_audit_event(ops_client):

backend/tests/test_demo_manifest.py

@@ -1,5 +1,10 @@
+from sqlalchemy import select
+
 from app.core.db import SessionLocal
+from app.models.outbox import OutboxEvent
 from app.seed_loader import reset_and_seed
+from app.services import demo_manifest
+from app.services.knowledge import KnowledgeHealth
 
 
 def test_demo_manifest_is_public(client):
@@ -52,3 +57,102 @@ def test_demo_manifest_ragcore_labelled_as_demo_mode_not_live(client):
     body = client.get("/api/v1/demo/manifest").json()
     ragcore = next(i for i in body["integrations"] if i["key"] == "ragcore")
     assert ragcore["status_code"] == "demoMode"
+
+
+def test_automation_scenario_requires_the_exact_prepared_failure():
+    db = SessionLocal()
+    try:
+        reset_and_seed(db)
+        event = db.scalar(
+            select(OutboxEvent).where(OutboxEvent.event_id == demo_manifest._FAILED_DEMO_EVENT_ID)
+        )
+        assert event is not None
+        event.last_error_code = "connectionError"
+        db.flush()
+
+        scenario = next(
+            item for item in demo_manifest._scenarios(db) if item.id == "automation-retry"
+        )
+        assert scenario.ready is False
+    finally:
+        db.rollback()
+        db.close()
+
+
+def test_knowledge_scenario_rejects_available_provider_with_verified_empty_corpus(
+    client, monkeypatch
+):
+    class EmptyKnowledgeProvider:
+        def health(self, language="en-GB"):
+            return KnowledgeHealth(
+                provider="ragcore",
+                available=True,
+                detail="Ready, but no indexed documents.",
+                tenant="fleet-ops",
+                workspace="mobilityops",
+                collection="procedures",
+                document_count=0,
+                source_document_count=4,
+                reported_synced_document_count=None,
+                reported_failed_document_count=None,
+                last_sync_at=None,
+                statistics_state="verified",
+            )
+
+    monkeypatch.setattr(demo_manifest, "get_knowledge_provider", EmptyKnowledgeProvider)
+
+    body = client.get("/api/v1/demo/manifest").json()
+    scenario = next(item for item in body["scenarios"] if item["id"] == "knowledge-question")
+    assert scenario["ready"] is False
+    assert scenario["blocked_reason_code"] == "knowledgeUnavailable"
+    ragcore = next(item for item in body["integrations"] if item["key"] == "ragcore")
+    assert ragcore["status_code"] == "unavailable"
+
+
+def test_knowledge_scenario_rejects_local_sources_when_index_count_is_unverified(
+    client, monkeypatch
+):
+    class SourceAwareKnowledgeProvider:
+        def health(self, language="en-GB"):
+            return KnowledgeHealth(
+                provider="ragcore",
+                available=True,
+                detail="Ready; index count endpoint is unavailable.",
+                tenant="fleet-ops",
+                workspace="mobilityops",
+                collection="procedures",
+                document_count=None,
+                source_document_count=4,
+                reported_synced_document_count=None,
+                reported_failed_document_count=None,
+                last_sync_at=None,
+                statistics_state="not_reported",
+            )
+
+    monkeypatch.setattr(demo_manifest, "get_knowledge_provider", SourceAwareKnowledgeProvider)
+
+    body = client.get("/api/v1/demo/manifest").json()
+    scenario = next(item for item in body["scenarios"] if item["id"] == "knowledge-question")
+    assert scenario["ready"] is False
+    assert scenario["blocked_reason_code"] == "knowledgeUnavailable"
+    ragcore = next(item for item in body["integrations"] if item["key"] == "ragcore")
+    assert ragcore["status_code"] == "unavailable"
+
+
+def test_knowledge_scenario_requires_provider_availability_even_with_documents():
+    health = KnowledgeHealth(
+        provider="ragcore",
+        available=False,
+        detail="Provider is unreachable.",
+        tenant="fleet-ops",
+        workspace="mobilityops",
+        collection="procedures",
+        document_count=4,
+        source_document_count=4,
+        reported_synced_document_count=None,
+        reported_failed_document_count=None,
+        last_sync_at=None,
+        statistics_state="verified",
+    )
+
+    assert demo_manifest._knowledge_scenario_ready(health) is False

backend/tests/test_dispatcher.py

@@ -4,6 +4,7 @@ import uuid
 from datetime import UTC, datetime, timedelta
 from types import SimpleNamespace
 
+import pytest
 from sqlalchemy import select
 
 from app.core.config import get_settings
@@ -65,12 +66,17 @@ def test_claim_marks_events_delivering():
 
 def test_deliver_one_success(monkeypatch):
     event_id = _make_pending_event("MO-002")
+    execution_id = "n8n-execution-123"
     dispatcher._claim_due_events()
 
     def fake_post(url, json, headers, timeout):
         return SimpleNamespace(
             raise_for_status=lambda: None,
-            json=lambda: {"ok": True, "event_id": str(event_id), "result": {}},
+            json=lambda: {
+                "ok": True,
+                "event_id": str(event_id),
+                "result": {"execution_id": execution_id},
+            },
         )
 
     monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
@@ -79,7 +85,7 @@ def test_deliver_one_success(monkeypatch):
     event = _get_event(event_id)
     assert event.delivery_status == "succeeded"
     assert event.attempts == 1
-    assert event.external_run_id == str(event_id)
+    assert event.external_run_id == execution_id
     assert event.last_error is None
     assert event.last_error_code is None
 
@@ -129,6 +135,106 @@ def test_deliver_one_treats_empty_2xx_body_as_failure(monkeypatch):
     assert event.last_error_code == "malformedResponse"
 
 
+def test_deliver_one_rejects_json_object_without_explicit_success_ack(monkeypatch):
+    event_id = _make_pending_event("MO-010")
+    dispatcher._claim_due_events()
+
+    def fake_post(url, json, headers, timeout):
+        return SimpleNamespace(
+            raise_for_status=lambda: None,
+            json=lambda: {},
+            status_code=200,
+        )
+
+    monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
+    dispatcher._deliver_one(event_id)
+
+    event = _get_event(event_id)
+    assert event.delivery_status == "pending"
+    assert event.attempts == 1
+    assert event.last_error_code == "malformedResponse"
+    assert event.external_run_id is None
+
+
+@pytest.mark.parametrize("result", [{}, {"execution_id": 123}, {"execution_id": " "}])
+def test_deliver_one_rejects_ack_without_valid_execution_id(monkeypatch, result):
+    event_id = _make_pending_event("MO-EXEC-ID")
+    dispatcher._claim_due_events()
+
+    def fake_post(url, json, headers, timeout):
+        return SimpleNamespace(
+            raise_for_status=lambda: None,
+            json=lambda: {"ok": True, "event_id": str(event_id), "result": result},
+            status_code=200,
+        )
+
+    monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
+    dispatcher._deliver_one(event_id)
+    event = _get_event(event_id)
+    assert event.delivery_status == "pending"
+    assert event.last_error_code == "malformedResponse"
+    assert event.external_run_id is None
+
+
+def test_deliver_one_rejects_success_ack_for_a_different_event(monkeypatch):
+    event_id = _make_pending_event("MO-011")
+    dispatcher._claim_due_events()
+    other_event_id = uuid.uuid4()
+
+    def fake_post(url, json, headers, timeout):
+        return SimpleNamespace(
+            raise_for_status=lambda: None,
+            json=lambda: {"ok": True, "event_id": str(other_event_id)},
+            status_code=200,
+        )
+
+    monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
+    dispatcher._deliver_one(event_id)
+
+    event = _get_event(event_id)
+    assert event.delivery_status == "pending"
+    assert event.attempts == 1
+    assert event.last_error_code == "mismatchedEventId"
+    assert event.external_run_id is None
+
+
+def test_late_delivery_outcome_cannot_overwrite_a_newer_lease(monkeypatch):
+    event_id = _make_pending_event("MO-LEASE-RACE")
+    dispatcher._claim_due_events()
+
+    def fake_post(url, json, headers, timeout):
+        # Simulate lease expiry/reclaim while the original worker is still in network
+        # I/O. The later claimant owns a different token and its state must win.
+        with SessionLocal() as db:
+            event = db.scalar(
+                select(OutboxEvent).where(OutboxEvent.event_id == event_id).with_for_update()
+            )
+            event.payload_json = {
+                **event.payload_json,
+                "_delivery_claim_token": "newer-worker-token",
+            }
+            event.next_attempt_at = datetime.now(UTC) + timedelta(minutes=1)
+            db.commit()
+        return SimpleNamespace(
+            raise_for_status=lambda: None,
+            json=lambda: {
+                "ok": True,
+                "event_id": str(event_id),
+                "result": {"execution_id": "stale-worker-execution"},
+            },
+            status_code=200,
+        )
+
+    monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
+    dispatcher._deliver_one(event_id)
+
+    event = _get_event(event_id)
+    assert event.delivery_status == "delivering"
+    assert event.attempts == 0
+    assert event.external_run_id is None
+    assert event.payload_json["_delivery_claim_token"] == "newer-worker-token"
+
+
 def test_deliver_one_exhausts_attempts_to_failed(monkeypatch):
     event_id = _make_pending_event("MO-004")
     settings = get_settings()
@@ -139,7 +245,6 @@ def test_deliver_one_exhausts_attempts_to_failed(monkeypatch):
     monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
 
     for _ in range(settings.n8n_max_attempts):
-        dispatcher._claim_due_events()
         db = SessionLocal()
         try:
             event = db.scalar(select(OutboxEvent).where(OutboxEvent.event_id == event_id))
@@ -147,6 +252,8 @@ def test_deliver_one_exhausts_attempts_to_failed(monkeypatch):
             db.commit()
         finally:
             db.close()
+        claimed = dispatcher._claim_due_events(batch_size=1000)
+        assert event_id in claimed
         dispatcher._deliver_one(event_id)
 
     event = _get_event(event_id)
@@ -259,7 +366,11 @@ def test_run_dispatch_cycle_recovers_a_stale_lease_before_claiming(monkeypatch):
     def fake_post(url, json, headers, timeout):
         return SimpleNamespace(
             raise_for_status=lambda: None,
-            json=lambda: {"ok": True, "event_id": str(event_id), "result": {}},
+            json=lambda: {
+                "ok": True,
+                "event_id": str(event_id),
+                "result": {"execution_id": "n8n-recovered-execution"},
+            },
         )
 
     monkeypatch.setattr(dispatcher.httpx, "post", fake_post)
@@ -275,7 +386,11 @@ def test_run_dispatch_cycle_end_to_end(monkeypatch):
     def fake_post(url, json, headers, timeout):
         return SimpleNamespace(
             raise_for_status=lambda: None,
-            json=lambda: {"ok": True, "event_id": str(event_id), "result": {}},
+            json=lambda: {
+                "ok": True,
+                "event_id": str(event_id),
+                "result": {"execution_id": "n8n-cycle-execution"},
+            },
         )
 
     monkeypatch.setattr(dispatcher.httpx, "post", fake_post)

backend/tests/test_hardening.py

@@ -174,11 +174,12 @@ def test_return_idempotency_key_rejects_different_body(ops_client):
 
 
 def test_return_callback_rejects_malformed_correlation_id(client):
+    event_id = str(uuid.uuid4())
     response = client.post(
         "/api/v1/integrations/n8n/return-callback",
-        json={"follow_up": "cleaning", "correlation_id": "nope"},
+        json={"event_id": event_id, "follow_up": "cleaning", "correlation_id": "nope"},
         headers={
-            "Idempotency-Key": str(uuid.uuid4()),
+            "Idempotency-Key": event_id,
             "X-Service-Token": get_settings().n8n_callback_token,
         },
     )
@@ -195,10 +196,14 @@ def test_blocked_checkout_booking_can_be_cancelled(ops_client):
         json={
             "customer_ref": "CUS-0002",
             "vehicle_ref": vehicle["public_ref"],
-            "requirements_complete": True,
             **window,
         },
     ).json()
+    confirmed = ops_client.post(
+        f"/api/v1/bookings/{booking['public_ref']}/complete-requirements",
+        json={"confirmation": "Licence and rental conditions checked"},
+    )
+    assert confirmed.status_code == 200
     checkout = ops_client.post(
         f"/api/v1/bookings/{booking['public_ref']}/checkout",
         json={

backend/tests/test_integration_status.py

@@ -1,8 +1,14 @@
-from sqlalchemy import select
+import uuid
+from datetime import UTC, datetime
+
+import pytest
+from sqlalchemy import delete, select
 
 from app.core.db import SessionLocal
+from app.models.audit import AuditEvent
 from app.models.outbox import OutboxEvent
 from app.seed_loader import reset_and_seed
+from app.services import integration_status
 
 
 def _reseed() -> None:
@@ -108,6 +114,101 @@ def test_integration_status_is_operational_once_all_failed_events_resolved(ops_c
     assert body["state"] == "operational"
 
 
+@pytest.mark.parametrize("delivery_status", ["pending", "delivering"])
+def test_queued_work_without_any_success_is_not_reported_operational(delivery_status):
+    _reseed()
+    db = SessionLocal()
+    try:
+        for event in db.scalars(select(OutboxEvent)).all():
+            event.delivery_status = delivery_status
+            event.last_error = None
+            event.last_error_code = None
+        db.execute(
+            delete(AuditEvent).where(
+                AuditEvent.action.in_(
+                    {
+                        "data_quality_scan_run",
+                        "n8n_procedures_synced",
+                        "n8n_workflow_failure_registered",
+                        "n8n_workflow_heartbeat",
+                    }
+                )
+            )
+        )
+        db.flush()
+
+        status = integration_status.derive_n8n_status(db)
+
+        assert status.succeeded == 0
+        assert getattr(status, delivery_status) > 0
+        assert status.state == "no_evidence"
+    finally:
+        db.rollback()
+        db.close()
+
+
+def test_historical_success_is_not_green_when_webhook_is_unconfigured(monkeypatch):
+    _reseed()
+    with SessionLocal() as db:
+        monkeypatch.setattr(integration_status.settings, "n8n_dispatch_enabled", True)
+        monkeypatch.setattr(integration_status.settings, "n8n_webhook_url", "")
+        status = integration_status.derive_n8n_status(db)
+        assert status.configured is False
+        assert status.succeeded > 0
+        assert status.state == "unavailable"
+
+
+def test_null_coded_real_failure_sets_latest_failure_timestamp():
+    _reseed()
+    with SessionLocal() as db:
+        event = db.scalar(
+            select(OutboxEvent).where(OutboxEvent.delivery_status == "succeeded").limit(1)
+        )
+        event.delivery_status = "failed"
+        event.last_error_code = None
+        db.flush()
+        status = integration_status.derive_n8n_status(db)
+        assert status.unexpected_failed == 1
+        assert status.latest_failure_at is not None
+        db.rollback()
+
+
+def test_unreachable_hub_invalidates_historical_operational_claim(monkeypatch):
+    db = SessionLocal()
+    try:
+        db.add(
+            AuditEvent(
+                actor_type="service",
+                actor_id=None,
+                actor_label="itworx-mcp-hub",
+                action="mcp_tool_request",
+                entity_type="integration",
+                entity_id=None,
+                correlation_id=uuid.uuid4(),
+                before_json=None,
+                after_json=None,
+                metadata_json={"tool": "operations_summary"},
+                occurred_at=datetime.now(UTC),
+            )
+        )
+        db.flush()
+        monkeypatch.setattr(integration_status.settings, "mcp_hub_registration_enabled", True)
+        monkeypatch.setattr(integration_status, "_check_hub_reachable", lambda: False)
+
+        unreachable = integration_status.derive_mcp_hub_status(db)
+
+        assert unreachable.total_calls > 0
+        assert unreachable.hub_reachable is False
+        assert unreachable.state == "no_evidence"
+
+        monkeypatch.setattr(integration_status, "_check_hub_reachable", lambda: True)
+        reachable = integration_status.derive_mcp_hub_status(db)
+        assert reachable.state == "operational"
+    finally:
+        db.rollback()
+        db.close()
+
+
 def test_integration_status_lists_all_four_canonical_workflows(ops_client):
     body = ops_client.get("/api/v1/integrations/status").json()["n8n"]
     assert body["expected_workflow_count"] == 4

backend/tests/test_integrations.py

@@ -1,4 +1,5 @@
 import uuid
+from concurrent.futures import ThreadPoolExecutor
 
 from app.core.config import get_settings
 
@@ -12,19 +13,29 @@ def _callback_headers(event_id: str, token: str | None = None):
 
 
 def test_callback_rejects_wrong_service_token(client):
+    event_id = str(uuid.uuid4())
     response = client.post(
         "/api/v1/integrations/n8n/return-callback",
-        json={"follow_up": "cleaning"},
-        headers=_callback_headers(str(uuid.uuid4()), token="wrong-token"),
+        json={
+            "event_id": event_id,
+            "correlation_id": str(uuid.uuid4()),
+            "follow_up": "cleaning",
+        },
+        headers=_callback_headers(event_id, token="wrong-token"),
     )
     assert response.status_code == 401
 
 
 def test_callback_unknown_event_returns_404(client):
+    event_id = str(uuid.uuid4())
     response = client.post(
         "/api/v1/integrations/n8n/return-callback",
-        json={"follow_up": "cleaning"},
-        headers=_callback_headers(str(uuid.uuid4())),
+        json={
+            "event_id": event_id,
+            "correlation_id": str(uuid.uuid4()),
+            "follow_up": "cleaning",
+        },
+        headers=_callback_headers(event_id),
     )
     assert response.status_code == 404
 
@@ -39,13 +50,14 @@ def test_callback_is_idempotent_by_event_id(client, ops_client):
     db = SessionLocal()
     try:
         booking = db.scalar(select(Booking).limit(1))
+        correlation_id = uuid.uuid4()
         event = OutboxEvent(
             event_id=uuid.uuid4(),
             event_type="vehicle.returned.v1",
             aggregate_type="booking",
             aggregate_id=booking.id,
             payload_json={
-                "correlation_id": str(uuid.uuid4()),
+                "correlation_id": str(correlation_id),
                 "aggregate": {
                     "type": "booking",
                     "id": str(booking.id),
@@ -66,12 +78,22 @@ def test_callback_is_idempotent_by_event_id(client, ops_client):
 
     first = client.post(
         "/api/v1/integrations/n8n/return-callback",
-        json={"follow_up": "cleaning", "summary": "test"},
+        json={
+            "event_id": event_id,
+            "correlation_id": str(correlation_id),
+            "follow_up": "cleaning",
+            "summary": "test",
+        },
         headers=_callback_headers(event_id),
     )
     second = client.post(
         "/api/v1/integrations/n8n/return-callback",
-        json={"follow_up": "cleaning", "summary": "test"},
+        json={
+            "event_id": event_id,
+            "correlation_id": str(correlation_id),
+            "follow_up": "cleaning",
+            "summary": "test",
+        },
         headers=_callback_headers(event_id),
     )
     assert first.status_code == 200
@@ -82,6 +104,79 @@ def test_callback_is_idempotent_by_event_id(client, ops_client):
     ).json()
     matching = [e for e in audit_events if e["metadata"]["event_id"] == event_id]
     assert len(matching) == 1
+    assert matching[0]["correlation_id"] == str(correlation_id)
+
+
+def test_callback_rejects_crossed_event_or_correlation(client):
+    from sqlalchemy import select
+
+    from app.core.db import SessionLocal
+    from app.models.outbox import OutboxEvent
+
+    with SessionLocal() as db:
+        event = db.scalar(select(OutboxEvent).limit(1))
+        event_id = str(event.event_id)
+        correlation_id = event.payload_json["correlation_id"]
+
+    crossed_event = client.post(
+        "/api/v1/integrations/n8n/return-callback",
+        json={
+            "event_id": str(uuid.uuid4()),
+            "correlation_id": correlation_id,
+            "follow_up": "cleaning",
+        },
+        headers=_callback_headers(event_id),
+    )
+    assert crossed_event.status_code == 409
+    assert crossed_event.json()["error"]["code"] == "CALLBACK_EVENT_MISMATCH"
+
+    crossed_correlation = client.post(
+        "/api/v1/integrations/n8n/return-callback",
+        json={
+            "event_id": event_id,
+            "correlation_id": str(uuid.uuid4()),
+            "follow_up": "cleaning",
+        },
+        headers=_callback_headers(event_id),
+    )
+    assert crossed_correlation.status_code == 409
+    assert crossed_correlation.json()["error"]["code"] == "CALLBACK_CORRELATION_MISMATCH"
+
+
+def test_callback_concurrent_retries_record_one_audit(client, ops_client):
+    from sqlalchemy import select
+
+    from app.core.db import SessionLocal
+    from app.models.outbox import OutboxEvent
+
+    with SessionLocal() as db:
+        event = db.scalar(select(OutboxEvent).limit(1))
+        event_id = str(event.event_id)
+        correlation_id = event.payload_json["correlation_id"]
+    body = {
+        "event_id": event_id,
+        "correlation_id": correlation_id,
+        "follow_up": "cleaning",
+    }
+
+    def post_callback(_index: int):
+        return client.post(
+            "/api/v1/integrations/n8n/return-callback",
+            json=body,
+            headers=_callback_headers(event_id),
+        )
+
+    with ThreadPoolExecutor(max_workers=2) as pool:
+        responses = list(pool.map(post_callback, range(2)))
+    assert [response.status_code for response in responses] == [200, 200]
+    matching = [
+        event
+        for event in ops_client.get(
+            "/api/v1/audit", params={"action": "n8n_return_followup_recorded"}
+        ).json()
+        if event["metadata"]["event_id"] == event_id
+    ]
+    assert len(matching) == 1
 
 
 def test_scheduled_scan_rejects_wrong_service_token(client):
@@ -183,6 +278,42 @@ def test_workflow_error_registers_and_is_idempotent_by_execution_id(client, ops_
     assert matching[0]["after"]["retry_action"] == "n8n will retry automatically"
 
 
+def test_workflow_error_preserves_correlation_and_rejects_malformed(client, ops_client):
+    settings = get_settings()
+    headers = {"X-Service-Token": settings.n8n_callback_token}
+    execution_id = str(uuid.uuid4())
+    correlation_id = str(uuid.uuid4())
+    accepted = client.post(
+        "/api/v1/integrations/n8n/workflow-error",
+        json=_workflow_error_body(execution_id, correlation_id=correlation_id),
+        headers=headers,
+    )
+    assert accepted.status_code == 200
+    matching = [
+        event
+        for event in ops_client.get(
+            "/api/v1/audit", params={"action": "n8n_workflow_failure_registered"}
+        ).json()
+        if event["metadata"]["execution_id"] == execution_id
+    ]
+    assert len(matching) == 1
+    assert matching[0]["correlation_id"] == correlation_id
+
+    malformed_execution = str(uuid.uuid4())
+    malformed = client.post(
+        "/api/v1/integrations/n8n/workflow-error",
+        json=_workflow_error_body(malformed_execution, correlation_id="not-a-uuid"),
+        headers=headers,
+    )
+    assert malformed.status_code == 422
+    assert all(
+        event["metadata"]["execution_id"] != malformed_execution
+        for event in ops_client.get(
+            "/api/v1/audit", params={"action": "n8n_workflow_failure_registered"}
+        ).json()
+    )
+
+
 def test_workflow_error_bounds_summary_length(client):
     settings = get_settings()
     response = client.post(
@@ -266,6 +397,26 @@ def test_procedures_sync_result_registers_and_is_idempotent(client, ops_client):
     assert ragcore_sync["last_seen_at"] is not None
 
 
+def test_failed_or_partial_procedure_sync_is_never_reported_healthy(client, ops_client):
+    settings = get_settings()
+    headers = {"X-Service-Token": settings.n8n_callback_token}
+    for synced, failed in ((0, 33), (32, 1)):
+        execution_id = str(uuid.uuid4())
+        response = client.post(
+            "/api/v1/integrations/n8n/procedures-sync-result",
+            json={"execution_id": execution_id, "synced": synced, "failed": failed},
+            headers=headers,
+        )
+        assert response.status_code == 200
+
+        status = ops_client.get("/api/v1/integrations/status").json()["n8n"]
+        workflow = next(w for w in status["workflows"] if "RAGcore" in w["name"])
+        assert workflow["state"] == "failed"
+        assert workflow["last_status"] == "failed"
+        assert workflow["last_execution_id"] == execution_id
+        assert status["state"] == "degraded"
+
+
 def test_workflow_heartbeat_is_idempotent_and_drives_live_status(client, ops_client):
     settings = get_settings()
     execution_id = str(uuid.uuid4())

backend/tests/test_knowledge.py

@@ -1,9 +1,12 @@
 from __future__ import annotations
 
+import hashlib
 import re
+import uuid
 from pathlib import Path
 
 import httpx
+import pytest
 
 from app.api.routers import knowledge as knowledge_router
 from app.core.config import get_settings
@@ -244,11 +247,11 @@ def test_ragcore_status_preserves_stronger_verified_index_evidence(client, ops_c
 
 
 class _FakeResponse:
-    def __init__(self, status_code: int, body: dict):
+    def __init__(self, status_code: int, body: object):
         self.status_code = status_code
         self._body = body
 
-    def json(self) -> dict:
+    def json(self) -> object:
         return self._body
 
 
@@ -260,6 +263,7 @@ class _FakeClient:
         post_responses=None,
         raise_on=None,
         get_handler=None,
+        requests=None,
     ):
         self._get_response = get_response
         self._post_response = post_response
@@ -270,6 +274,7 @@ class _FakeClient:
         self._post_responses = post_responses or {}
         self._raise_on = raise_on
         self._get_handler = get_handler
+        self.requests = requests if requests is not None else []
 
     def __enter__(self):
         return self
@@ -289,6 +294,7 @@ class _FakeClient:
     def post(self, path, json=None):
         if self._raise_on == "post":
             raise httpx.ConnectError("no ragcore in this environment")
+        self.requests.append((path, json))
         return self._post_responses.get(path, self._post_response)
 
 
@@ -393,22 +399,107 @@ def test_ragcore_provider_health_degrades_on_connection_error(monkeypatch):
     assert "unavailable" in health.detail.lower()
 
 
-def _answers_body(**overrides) -> dict:
+_EXCERPTS = {
+    ("en-GB", "damage-procedure"): (
+        "When a vehicle returns with visible or reported damage, mark damage in the "
+        "return inspection, add a concise factual description and keep the vehicle "
+        "blocked."
+    ),
+    ("en-GB", "vehicle-return-procedure"): (
+        "Open the active booking and record the ending odometer, fuel level, cleanliness, "
+        "visible damage, technical warnings and relevant notes."
+    ),
+    ("en-GB", "cleaning-checklist"): (
+        "Cleaning completion alone does not make a blocked or maintenance vehicle "
+        "available. Fleet Ops derives availability from all active restrictions."
+    ),
+    ("en-GB", "maintenance-escalation"): (
+        "Escalate when a technical warning is reported, the service threshold is reached, "
+        "a safety-related defect is observed or an existing maintenance block remains "
+        "unresolved."
+    ),
+    ("nl-BE", "damage-procedure"): (
+        "Wanneer een voertuig terugkomt met zichtbare of gemelde schade, markeer de schade "
+        "in de retourinspectie, voeg een beknopte feitelijke beschrijving toe en houd het "
+        "voertuig geblokkeerd."
+    ),
+    ("nl-BE", "vehicle-return-procedure"): (
+        "Open de actieve boeking en registreer de eindkilometerstand, het brandstofniveau, "
+        "de netheid, zichtbare schade, technische waarschuwingen en relevante notities."
+    ),
+}
+
+
+def _managed_document(provider: RAGcoreKnowledgeProvider, document_id: str, language: str):
+    return next(
+        document
+        for document in provider._managed_documents_by_source_id.values()
+        if document.document_id == document_id and document.language == language
+    )
+
+
+def _citation(
+    provider: RAGcoreKnowledgeProvider,
+    document_id: str,
+    *,
+    language: str = "en-GB",
+    section: str = "Procedure",
+    seed: str = "1",
+) -> dict:
+    document = _managed_document(provider, document_id, language)
+    excerpt = _EXCERPTS[(language, document_id)]
+    return {
+        "id": str(uuid.uuid5(uuid.NAMESPACE_URL, f"citation:{language}:{document_id}:{seed}")),
+        # These are deliberately opaque RAGcore-owned UUIDs, not Fleet Ops' stable
+        # human-readable procedure id.
+        "document_id": str(
+            uuid.uuid5(uuid.NAMESPACE_URL, f"ragcore-document:{language}:{document_id}")
+        ),
+        "document_version_id": str(
+            uuid.uuid5(
+                uuid.NAMESPACE_URL,
+                f"ragcore-document-version:{language}:{document_id}:{seed}",
+            )
+        ),
+        "title": "untrusted-provider-title.md",
+        "section": section,
+        "excerpt": excerpt,
+        "excerpt_sha256": hashlib.sha256(excerpt.encode("utf-8")).hexdigest(),
+        "source_uri": f"ragcore://source/{document.source_id}",
+        "source_id": document.source_id,
+        "locator": f"{document.document_id}.md",
+    }
+
+
+def _answers_body(provider: RAGcoreKnowledgeProvider, **overrides) -> dict:
+    citation = _citation(provider, "damage-procedure", section="Detection")
+    answer = "Report damage and route the vehicle to maintenance."
     body = {
-        "answer": "Report damage and route the vehicle to maintenance.",
+        "answer_id": str(uuid.uuid4()),
+        "retrieval_run_id": str(uuid.uuid4()),
+        "answer": answer,
         "answerability": "answerable",
-        "citations": [
-            {
-                "id": "cite-1",
-                "document_id": "doc-1",
-                "document_version_id": "version-1",
-                "title": "Damage handling procedure",
-                "section": "Detection",
-                "excerpt": "Inspect the vehicle for visible damage.",
-            }
-        ],
+        "citations": [citation],
+        "claims": [{"text": answer, "citation_ids": [citation["id"]]}],
     }
     body.update(overrides)
+    if "claims" not in overrides:
+        effective_answer = body.get("answer")
+        effective_citations = body.get("citations")
+        body["claims"] = (
+            [
+                {
+                    "text": effective_answer,
+                    "citation_ids": [item["id"] for item in effective_citations],
+                }
+            ]
+            if isinstance(effective_answer, str)
+            and effective_answer
+            and isinstance(effective_citations, list)
+            and effective_citations
+            and all(isinstance(item, dict) and "id" in item for item in effective_citations)
+            else []
+        )
     return body
 
 
@@ -418,47 +509,178 @@ def test_ragcore_provider_grounded_answer_maps_citations_to_sources(monkeypatch)
     monkeypatch.setattr(
         provider,
         "_client",
-        lambda: _FakeClient(post_response=_FakeResponse(200, _answers_body())),
+        lambda: _FakeClient(post_response=_FakeResponse(200, _answers_body(provider))),
     )
     answer = provider.ask("What must I do about damage?", "test-correlation-grounded")
     assert answer.evidence_state == "grounded"
     assert answer.answer
     assert len(answer.sources) == 1
     source = answer.sources[0]
-    assert source.document_id == "doc-1"
+    assert source.document_id == "damage-procedure"
     assert source.title == "Damage handling procedure"
-    assert source.version == "version-1"
+    assert source.version == "1.3"
     assert source.section == "Detection"
     assert source.excerpt
 
 
+@pytest.mark.parametrize(
+    "mutate",
+    [
+        lambda body: body.pop("claims"),
+        lambda body: body.update(claims=[]),
+        lambda body: body["claims"][0].update(citation_ids=[str(uuid.uuid4())]),
+        lambda body: body.pop("answer_id"),
+        lambda body: body.update(retrieval_run_id="not-a-uuid"),
+    ],
+)
+def test_ragcore_answer_requires_valid_claim_citation_contract(monkeypatch, mutate):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    body = _answers_body(provider)
+    mutate(body)
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(post_response=_FakeResponse(200, body)),
+    )
+
+    answer = provider.ask("What must I do about damage?", "test-invalid-claim-contract")
+
+    assert answer.evidence_state != "grounded"
+    assert answer.answer == ""
+    assert answer.sources == []
+
+
+def test_ragcore_requests_are_scoped_to_managed_sources_for_requested_language(
+    monkeypatch,
+):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    requests = []
+    fake_client = _FakeClient(
+        post_responses={
+            "/v1/answers": _FakeResponse(503, {}),
+            "/v1/search": _FakeResponse(200, _search_body(provider, "nl-BE")),
+        },
+        requests=requests,
+    )
+    monkeypatch.setattr(provider, "_client", lambda: fake_client)
+
+    answer = provider.ask(
+        "Wat is de procedure voor een voertuigretour?",
+        "language-filter",
+        "nl-BE",
+    )
+
+    assert answer.evidence_state == "grounded"
+    assert [path for path, _payload in requests] == ["/v1/answers", "/v1/search"]
+    expected_source_ids = provider._managed_source_ids("nl-BE")
+    assert len(expected_source_ids) == 11
+    assert all(uuid.UUID(source_id) for source_id in expected_source_ids)
+    for _path, payload in requests:
+        assert payload["filters"] == {"source_ids": expected_source_ids}
+        assert payload["requested_space_ids"] == ["space-1"]
+
+
 def test_ragcore_sources_deduplicate_reuploaded_versions_and_cap_cards(monkeypatch):
     provider = RAGcoreKnowledgeProvider()
     monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
     citations = []
-    for index in range(5):
+    document_ids = [
+        "damage-procedure",
+        "damage-procedure",
+        "vehicle-return-procedure",
+        "cleaning-checklist",
+        "maintenance-escalation",
+    ]
+    for index, document_id in enumerate(document_ids):
         citations.append(
-            {
-                "id": f"cite-{index}",
-                "document_id": f"doc-{index}",
-                "document_version_id": f"version-{index}",
-                "title": "Damage procedure" if index < 2 else f"Procedure {index}",
-                "section": "Return",
-                "excerpt": (
-                    f"Record visible damage before release, chunk {index}."
-                    if index < 2
-                    else f"Unique procedure evidence {index}."
-                ),
-            }
+            _citation(
+                provider,
+                document_id,
+                section="Return",
+                seed=str(index),
+            )
         )
     monkeypatch.setattr(
         provider,
         "_client",
-        lambda: _FakeClient(post_response=_FakeResponse(200, _answers_body(citations=citations))),
+        lambda: _FakeClient(
+            post_response=_FakeResponse(200, _answers_body(provider, citations=citations))
+        ),
     )
     answer = provider.ask("What must I do about vehicle damage?", "dedupe-test")
     assert len(answer.sources) == 3
-    assert sum(source.title == "Damage procedure" for source in answer.sources) == 1
+    assert sum(source.title == "Damage handling procedure" for source in answer.sources) == 1
+
+
+def test_ragcore_answer_rejects_unknown_document_citation(monkeypatch):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(
+            post_response=_FakeResponse(
+                200,
+                _answers_body(
+                    provider,
+                    answer="A plausible-looking but unmanaged answer.",
+                    citations=[
+                        {
+                            **_citation(provider, "damage-procedure"),
+                            "source_id": str(uuid.uuid4()),
+                        }
+                    ],
+                ),
+            )
+        ),
+    )
+
+    answer = provider.ask("What must I do about damage?", "unknown-answer-citation")
+
+    assert answer.evidence_state == "insufficient"
+    assert answer.answer == ""
+    assert answer.sources == []
+
+
+@pytest.mark.parametrize(
+    ("field_name", "bad_value"),
+    [
+        ("id", "not-a-uuid"),
+        ("document_id", "not-a-uuid"),
+        ("document_version_id", "00000000-0000-0000-0000-000000000000"),
+        ("source_id", "00000000-0000-4000-8000-000000000099"),
+        ("source_uri", "ragcore://source/00000000-0000-4000-8000-000000000099"),
+        ("locator", "another-procedure.md"),
+        ("excerpt_sha256", "0" * 64),
+        ("title", None),
+        ("section", {"not": "a string"}),
+    ],
+)
+def test_ragcore_rejects_broken_managed_source_provenance(field_name, bad_value):
+    provider = RAGcoreKnowledgeProvider()
+    citation = _citation(provider, "damage-procedure")
+    citation[field_name] = bad_value
+
+    assert provider._managed_source(citation, "en-GB") is None
+
+
+def test_ragcore_rejects_fabricated_excerpt_even_with_matching_hash():
+    provider = RAGcoreKnowledgeProvider()
+    citation = _citation(provider, "damage-procedure")
+    fabricated = "Invent a repair price and promise it to the customer."
+    citation["excerpt"] = fabricated
+    citation["excerpt_sha256"] = hashlib.sha256(fabricated.encode("utf-8")).hexdigest()
+
+    assert provider._managed_source(citation, "en-GB") is None
+
+
+def test_ragcore_never_relabels_an_english_source_as_dutch():
+    provider = RAGcoreKnowledgeProvider()
+    citation = _citation(provider, "damage-procedure", language="en-GB")
+
+    assert provider._managed_source(citation, "nl-BE") is None
 
 
 def test_knowledge_feedback_is_audited_and_can_be_changed(ops_client):
@@ -503,6 +725,7 @@ def test_ragcore_provider_not_answerable_is_insufficient_and_never_fabricates(mo
             post_response=_FakeResponse(
                 200,
                 _answers_body(
+                    provider,
                     answer="This should never be shown.",
                     answerability="not_answerable",
                     citations=[],
@@ -524,7 +747,8 @@ def test_ragcore_provider_answerable_without_citations_is_insufficient(monkeypat
         "_client",
         lambda: _FakeClient(
             post_response=_FakeResponse(
-                200, _answers_body(answerability="answerable", citations=[])
+                200,
+                _answers_body(provider, answerability="answerable", citations=[]),
             )
         ),
     )
@@ -565,19 +789,66 @@ def test_ragcore_provider_malformed_response_is_unavailable(monkeypatch):
     assert answer.evidence_state == "unavailable"
 
 
-def _search_body(**overrides) -> dict:
+def test_ragcore_provider_malformed_top_level_bodies_do_not_escape(monkeypatch):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(
+            post_responses={
+                "/v1/answers": _FakeResponse(200, ["not", "an", "object"]),
+                "/v1/search": _FakeResponse(200, None),
+            }
+        ),
+    )
+
+    answer = provider.ask("Anything?", "test-correlation-malformed-top-level")
+
+    assert answer.evidence_state == "unavailable"
+    assert answer.answer == ""
+    assert answer.sources == []
+
+
+def test_ragcore_answer_with_malformed_citation_is_insufficient(monkeypatch):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(
+            post_response=_FakeResponse(
+                200,
+                _answers_body(provider, citations=[None]),
+            )
+        ),
+    )
+
+    answer = provider.ask("What must I do about damage?", "malformed-answer-citation")
+
+    assert answer.evidence_state == "insufficient"
+    assert answer.answer == ""
+    assert answer.sources == []
+
+
+def _search_body(
+    provider: RAGcoreKnowledgeProvider,
+    language: str = "en-GB",
+    **overrides,
+) -> dict:
     body = {
+        "retrieval_run_id": str(uuid.uuid4()),
+        "effective_space_ids": ["00000000-0000-4000-8000-000000000001"],
         "results": [
             {
-                "chunk_id": "chunk-1",
-                "citation": {
-                    "id": "cite-1",
-                    "document_id": "doc-1",
-                    "document_version_id": "version-1",
-                    "title": "Vehicle return procedure",
-                    "section": "Return",
-                    "excerpt": "Register the return odometer reading before releasing the vehicle.",
-                },
+                "chunk_id": str(uuid.uuid4()),
+                "text": _EXCERPTS[(language, "vehicle-return-procedure")],
+                "citation": _citation(
+                    provider,
+                    "vehicle-return-procedure",
+                    language=language,
+                    section="Return",
+                ),
                 "rank": 1,
                 "scores": {"dense": None, "sparse": None, "fused": 0.5, "rerank": None},
             }
@@ -588,6 +859,31 @@ def _search_body(**overrides) -> dict:
     return body
 
 
+def test_ragcore_search_ignores_malformed_result_and_citation_bodies(monkeypatch):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    malformed_search = _search_body(
+        provider,
+        results=[None, {"citation": ["not-an-object"], "scores": "not-an-object"}],
+    )
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(
+            post_responses={
+                "/v1/answers": _FakeResponse(503, {}),
+                "/v1/search": _FakeResponse(200, malformed_search),
+            }
+        ),
+    )
+
+    answer = provider.ask("What is the vehicle return procedure?", "malformed-search-items")
+
+    assert answer.evidence_state == "insufficient"
+    assert answer.answer == ""
+    assert answer.sources == []
+
+
 def test_ragcore_provider_falls_back_to_search_when_answers_unavailable(monkeypatch):
     """/v1/answers itself failing (a real RAGcore-side outage in its generation step,
     not a real 'insufficient evidence' classification) must not silently degrade
@@ -601,26 +897,24 @@ def test_ragcore_provider_falls_back_to_search_when_answers_unavailable(monkeypa
         lambda: _FakeClient(
             post_responses={
                 "/v1/answers": _FakeResponse(503, {"code": "VALIDATION_RETRIES_EXHAUSTED"}),
-                "/v1/search": _FakeResponse(200, _search_body()),
+                "/v1/search": _FakeResponse(200, _search_body(provider)),
             }
         ),
     )
     answer = provider.ask("What is the vehicle return procedure?", "test-correlation-fallback")
     assert answer.evidence_state == "grounded"
-    assert "Register the return odometer reading" in answer.answer
+    assert "Open the active booking and record the ending odometer" in answer.answer
     assert "Vehicle return procedure" in answer.answer
     assert len(answer.sources) == 1
     assert answer.sources[0].title == "Vehicle return procedure"
-    assert answer.sources[0].excerpt == (
-        "Register the return odometer reading before releasing the vehicle."
-    )
+    assert answer.sources[0].excerpt == _EXCERPTS[("en-GB", "vehicle-return-procedure")]
 
 
 def test_ragcore_answers_circuit_skips_repeated_generation_failure(monkeypatch):
     provider = RAGcoreKnowledgeProvider()
     monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
     monkeypatch.setattr(provider._settings, "ragcore_answers_circuit_breaker_seconds", 60.0)
-    search_response = _FakeResponse(200, _search_body())
+    search_response = _FakeResponse(200, _search_body(provider))
     monkeypatch.setattr(
         provider,
         "_client",
@@ -632,8 +926,7 @@ def test_ragcore_answers_circuit_skips_repeated_generation_failure(monkeypatch):
         ),
     )
     assert (
-        provider.ask("What is the vehicle return procedure?", "first").evidence_state
-        == "grounded"
+        provider.ask("What is the vehicle return procedure?", "first").evidence_state == "grounded"
     )
 
     monkeypatch.setattr(
@@ -654,7 +947,7 @@ def test_ragcore_provider_fallback_answer_is_localized(monkeypatch):
         lambda: _FakeClient(
             post_responses={
                 "/v1/answers": _FakeResponse(503, {"code": "VALIDATION_RETRIES_EXHAUSTED"}),
-                "/v1/search": _FakeResponse(200, _search_body()),
+                "/v1/search": _FakeResponse(200, _search_body(provider, "nl-BE")),
             }
         ),
     )
@@ -676,7 +969,7 @@ def test_ragcore_provider_fallback_with_no_search_results_is_insufficient(monkey
         lambda: _FakeClient(
             post_responses={
                 "/v1/answers": _FakeResponse(503, {"code": "VALIDATION_RETRIES_EXHAUSTED"}),
-                "/v1/search": _FakeResponse(200, _search_body(results=[])),
+                "/v1/search": _FakeResponse(200, _search_body(provider, results=[])),
             }
         ),
     )
@@ -695,7 +988,7 @@ def test_ragcore_search_fallback_rejects_out_of_domain_question(monkeypatch):
         lambda: _FakeClient(
             post_responses={
                 "/v1/answers": _FakeResponse(503, {}),
-                "/v1/search": _FakeResponse(200, _search_body()),
+                "/v1/search": _FakeResponse(200, _search_body(provider)),
             }
         ),
     )
@@ -707,19 +1000,66 @@ def test_ragcore_search_fallback_rejects_out_of_domain_question(monkeypatch):
     assert answer.answer == ""
 
 
+def test_ragcore_search_fallback_rejects_unknown_document_citation(monkeypatch):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    search = _search_body(provider)
+    search["results"][0]["citation"]["source_id"] = str(uuid.uuid4())
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(
+            post_responses={
+                "/v1/answers": _FakeResponse(503, {}),
+                "/v1/search": _FakeResponse(200, search),
+            }
+        ),
+    )
+
+    answer = provider.ask(
+        "What is the vehicle return procedure?",
+        "unknown-search-citation",
+    )
+
+    assert answer.evidence_state == "insufficient"
+    assert answer.answer == ""
+    assert answer.sources == []
+
+
+def test_ragcore_search_fallback_rejects_vehicle_colour_despite_high_score(monkeypatch):
+    provider = RAGcoreKnowledgeProvider()
+    monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
+    search = _search_body(provider)
+    search["results"][0]["scores"]["fused"] = 1.0
+    monkeypatch.setattr(
+        provider,
+        "_client",
+        lambda: _FakeClient(
+            post_responses={
+                "/v1/answers": _FakeResponse(503, {}),
+                "/v1/search": _FakeResponse(200, search),
+            }
+        ),
+    )
+
+    answer = provider.ask("What colour is this vehicle?", "vehicle-colour")
+
+    assert answer.evidence_state == "insufficient"
+    assert answer.answer == ""
+
+
 def test_ragcore_search_fallback_prefers_damage_procedure(monkeypatch):
     provider = RAGcoreKnowledgeProvider()
     monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
-    search = _search_body()
+    search = _search_body(provider, "nl-BE", results=[])
     search["results"].append(
         {
-            "citation": {
-                "document_id": "damage-procedure",
-                "document_version_id": "version-2",
-                "title": "damage-procedure.md",
-                "section": "Damage",
-                "excerpt": "Record damage and keep the vehicle blocked.",
-            },
+            "citation": _citation(
+                provider,
+                "damage-procedure",
+                language="nl-BE",
+                section="Damage",
+            ),
             "rank": 2,
             "scores": {"fused": 0.01},
         }
@@ -743,16 +1083,15 @@ def test_ragcore_search_fallback_prefers_damage_procedure(monkeypatch):
 def test_ragcore_search_fallback_accepts_top_ranked_ragcore_damage_evidence(monkeypatch):
     provider = RAGcoreKnowledgeProvider()
     monkeypatch.setattr(provider._settings, "ragcore_space_id", "space-1")
-    search = _search_body()
+    search = _search_body(provider, "nl-BE", results=[])
     search["results"].append(
         {
-            "citation": {
-                "document_id": "damage-procedure",
-                "document_version_id": "version-2",
-                "title": "damage-procedure.md",
-                "section": "Damage",
-                "excerpt": "Record damage and keep the vehicle blocked.",
-            },
+            "citation": _citation(
+                provider,
+                "damage-procedure",
+                language="nl-BE",
+                section="Damage",
+            ),
             "rank": 1,
             # RAGcore uses reciprocal-rank fusion; a genuine rank-one result is about
             # 1 / (60 + 1), not a normalized 0..1 relevance score.

backend/tests/test_mcp_integrations.py

@@ -1,4 +1,12 @@
 from app.core.config import get_settings
+from app.main import app
+
+MCP_ROUTE_ALLOWLIST = {
+    ("GET", "/api/v1/integrations/mcp/operations-summary"),
+    ("GET", "/api/v1/integrations/mcp/attention-vehicles"),
+    ("GET", "/api/v1/integrations/mcp/vehicles/{vehicle_ref}"),
+    ("POST", "/api/v1/integrations/mcp/search-knowledge"),
+}
 
 
 def _headers(token: str | None = None, client_id: str = "test-mcp-client"):
@@ -154,3 +162,26 @@ def test_no_write_endpoints_exist_under_mcp_namespace(client):
     ]:
         response = getattr(client, method)(path, headers=_headers())
         assert response.status_code in (404, 405)
+
+
+def test_mcp_namespace_matches_exact_route_allowlist_and_rejects_lookalikes(client):
+    implemented = {
+        (method.upper(), path)
+        for path, operations in app.openapi()["paths"].items()
+        if path.startswith("/api/v1/integrations/mcp/")
+        for method in operations
+        if method in {"get", "post", "put", "patch", "delete"}
+    }
+    assert implemented == MCP_ROUTE_ALLOWLIST
+
+    lookalikes = [
+        ("get", "/api/v1/integrations/mcp-extra/operations-summary"),
+        ("get", "/api/v1/integrations/mcp/operations-summary-extra"),
+        ("get", "/api/v1/integrations/mcp/prefix/attention-vehicles"),
+        ("get", "/api/v1/integrations/mcp/attention-vehicles/suffix"),
+        ("post", "/api/v1/integrations/mcp/search-knowledge-extra"),
+        ("post", "/api/v1/integrations/mcp/prefix/search-knowledge"),
+    ]
+    for method, path in lookalikes:
+        response = client.request(method, path, headers=_headers(), json={})
+        assert response.status_code == 404, path

backend/tests/test_privacy.py

@@ -63,6 +63,24 @@ def test_eligible_customer_is_irreversibly_anonymized_without_pii_in_audit(ops_c
         )
         assert response.status_code == 200
         assert response.json()["status"] == "anonymized"
+        search = ops_client.get("/api/v1/customers", params={"query": "CUS-PRIVACY"})
+        assert search.status_code == 200
+        assert search.json() == []
+        window = {
+            "starts_at": "2090-01-01T10:00:00Z",
+            "ends_at": "2090-01-02T10:00:00Z",
+        }
+        available = ops_client.get("/api/v1/bookings/availability", params=window).json()
+        assert available
+        booking = ops_client.post(
+            "/api/v1/bookings",
+            json={
+                "customer_ref": "CUS-PRIVACY",
+                "vehicle_ref": available[0]["public_ref"],
+                **window,
+            },
+        )
+        assert booking.status_code == 422
         with SessionLocal() as db:
             customer = db.scalar(select(Customer).where(Customer.id == customer_id))
             assert customer is not None

backend/tests/test_seed.py

@@ -128,6 +128,23 @@ def test_seed_scenario_s4_booking_overlap():
         db.close()
 
 
+def test_seed_odometer_issues_expose_only_the_regressing_booking_as_correctable():
+    db = SessionLocal()
+    try:
+        reset_and_seed(db)
+        issue = _by_ref(db, DataQualityIssue, "DQ-0007")
+        assert issue is not None
+        assert issue.evidence_json["source_type"] == "return"
+        assert issue.evidence_json["related_refs"] == [
+            "INSP-0057",
+            "BK-H-0007",
+            "INSP-0007",
+        ]
+        assert issue.evidence_json["correctable_booking_refs"] == ["BK-H-0007"]
+    finally:
+        db.close()
+
+
 def test_seed_scenario_s5_failed_workflow_run():
     """S5: one seeded outbox event is durably 'failed' (terminal, retryable), not merely
     pending, so the background dispatcher never silently auto-heals it away."""

backend/tests/test_seed_generation.py

@@ -0,0 +1,73 @@
+from __future__ import annotations
+
+import csv
+import subprocess
+import sys
+from pathlib import Path
+
+REPOSITORY_ROOT = next(
+    parent
+    for parent in Path(__file__).resolve().parents
+    if (parent / "seed" / "generate_seed.py").is_file()
+)
+SEED_DIRECTORY = REPOSITORY_ROOT / "seed"
+
+
+def _rows_by_ref(path: Path) -> dict[str, dict[str, str]]:
+    with path.open(newline="", encoding="utf-8") as handle:
+        rows = list(csv.DictReader(handle))
+    assert all(None not in row for row in rows), f"malformed CSV row in {path.name}"
+    return {row["public_ref"]: row for row in rows}
+
+
+def test_generator_reproduces_committed_seed_snapshot_byte_for_byte(tmp_path: Path):
+    subprocess.run(
+        [
+            sys.executable,
+            str(SEED_DIRECTORY / "generate_seed.py"),
+            "--anchor",
+            "2026-08-01",
+            "--seed",
+            "20260801",
+            "--out",
+            str(tmp_path),
+        ],
+        cwd=REPOSITORY_ROOT,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+
+    committed_files = sorted(SEED_DIRECTORY.glob("*.csv"))
+    generated_files = sorted(tmp_path.glob("*.csv"))
+    assert [path.name for path in generated_files] == [path.name for path in committed_files]
+    for committed in committed_files:
+        generated = tmp_path / committed.name
+        assert generated.read_bytes() == committed.read_bytes(), (
+            f"{committed.name} differs from the deterministic generated snapshot"
+        )
+
+    bookings = _rows_by_ref(tmp_path / "bookings.csv")
+    inspections = _rows_by_ref(tmp_path / "inspections.csv")
+    issues = _rows_by_ref(tmp_path / "data_quality_issues.csv")
+
+    assert int(bookings["BK-H-0007"]["end_odometer_km"]) < int(
+        bookings["BK-H-0057"]["end_odometer_km"]
+    )
+    assert int(bookings["BK-H-0010"]["end_odometer_km"]) < int(
+        bookings["BK-H-0060"]["end_odometer_km"]
+    )
+    assert inspections["INSP-0007"]["odometer_km"] == bookings["BK-H-0007"]["end_odometer_km"]
+    assert inspections["INSP-0010"]["odometer_km"] == bookings["BK-H-0010"]["end_odometer_km"]
+    assert inspections["INSP-0001"]["completed_at"] == bookings["BK-H-0001"]["ends_at"]
+
+    expected_issue_refs = {f"DQ-{index:04d}" for index in range(5, 22)}
+    assert expected_issue_refs <= issues.keys()
+    assert all(
+        issues[public_ref]["evidence"] != "Synthetic deterministic seed issue"
+        for public_ref in expected_issue_refs
+    )
+    assert "INSP-0007" in issues["DQ-0007"]["evidence"]
+    assert "INSP-0057" in issues["DQ-0007"]["evidence"]
+    assert "INSP-0010" in issues["DQ-0010"]["evidence"]
+    assert "INSP-0060" in issues["DQ-0010"]["evidence"]

backend/tests/test_users.py

@@ -23,3 +23,22 @@ def test_manager_can_create_and_update_user(ops_client):
 
 def test_employee_cannot_manage_users(employee_client):
     assert employee_client.get("/api/v1/users").status_code == 403
+    assert (
+        employee_client.post(
+            "/api/v1/users",
+            json={
+                "email": "unauthorised@example.test",
+                "display_name": "Unauthorised User",
+                "role": "rental_employee",
+                "password": "a-secure-demo-password",
+            },
+        ).status_code
+        == 403
+    )
+    assert (
+        employee_client.patch(
+            "/api/v1/users/USR-OPS",
+            json={"display_name": "Unauthorised Change"},
+        ).status_code
+        == 403
+    )

backend/tests/test_vehicles.py

@@ -46,6 +46,12 @@ def test_vehicle_detail_includes_related_records(ops_client):
     assert len(body["quality_issues"]) >= 1
 
 
+def test_employee_vehicle_detail_never_exposes_quality_evidence(employee_client):
+    response = employee_client.get("/api/v1/vehicles/MO-016")
+    assert response.status_code == 200
+    assert response.json()["quality_issues"] == []
+
+
 def test_vehicle_detail_404_for_unknown_ref(ops_client):
     response = ops_client.get("/api/v1/vehicles/MO-999")
     assert response.status_code == 404
@@ -78,6 +84,53 @@ def test_manager_can_record_maintenance_and_release_vehicle(ops_client):
     assert released.json()["operational_status"] == "available"
 
 
+def test_low_maintenance_reading_keeps_canonical_and_opens_quality_issue(ops_client):
+    existing_issues = ops_client.get(
+        "/api/v1/data-quality/issues",
+        params={"status": "open", "rule_type": "odometer_regression"},
+    ).json()
+    unavailable_refs = {issue["entity_ref"] for issue in existing_issues}
+    vehicles = ops_client.get("/api/v1/vehicles", params={"status": "available"}).json()
+    vehicle = next(
+        candidate
+        for candidate in vehicles
+        if candidate["odometer_km"] > 0 and candidate["public_ref"] not in unavailable_refs
+    )
+
+    response = ops_client.post(
+        f"/api/v1/vehicles/{vehicle['public_ref']}/maintenance",
+        json={
+            "occurred_at": "2053-01-15T12:00:00Z",
+            "odometer_km": vehicle["odometer_km"] - 1,
+            "category": "inspection",
+            "summary": "Imported workshop reading requires verification.",
+            "mark_maintenance": True,
+        },
+    )
+
+    assert response.status_code == 201
+    detail = ops_client.get(f"/api/v1/vehicles/{vehicle['public_ref']}").json()
+    assert detail["odometer_km"] == vehicle["odometer_km"]
+    issues = ops_client.get(
+        "/api/v1/data-quality/issues",
+        params={"status": "open", "rule_type": "odometer_regression"},
+    ).json()
+    issue = next(item for item in issues if item["entity_ref"] == vehicle["public_ref"])
+    assert issue["evidence"]["source_type"] == "maintenance"
+    assert issue["evidence"]["correctable_booking_refs"] == []
+    issue_detail = ops_client.get(f"/api/v1/data-quality/issues/{issue['public_ref']}").json()
+    assert any(
+        snapshot["entity_type"] == "maintenance"
+        and snapshot["public_ref"] == response.json()["public_ref"]
+        for snapshot in issue_detail["related_snapshots"]
+    )
+    retained = ops_client.post(
+        f"/api/v1/data-quality/issues/{issue['public_ref']}/resolve-odometer-regression",
+        json={"decision": "retain_canonical"},
+    )
+    assert retained.status_code == 200
+
+
 def test_employee_cannot_record_maintenance(employee_client):
     response = employee_client.post(
         "/api/v1/vehicles/MO-001/maintenance",