fix(demo): anchor seeded dates to the real reset moment

Booking/inspection/maintenance/outbox dates were authored as absolute
timestamps around a fixed 2026-08-01 anchor and never re-anchored at
seed/reset time, so demo scenarios (e.g. BK-DEMO-RETURN) silently drifted
into the past. Every reset now shifts seeded dates by (today - authored
anchor); dashboard's "today" filter uses real wall-clock time instead of
the now-removed frozen demo_today setting. Adds seed-validation tests
proving scenarios S1/S2/S4/S5 are present and internally consistent after
every reset.

backend/tests/test_seed.py

@@ -1,13 +1,16 @@
+from datetime import UTC, datetime
+
 from sqlalchemy import func, select
 
 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.outbox import OutboxEvent
 from app.models.user import User
 from app.models.vehicle import Vehicle
-from app.seed_loader import reset_and_seed
+from app.seed_loader import SEED_AUTHORED_ANCHOR, reset_and_seed
 
 
 def test_seed_counts_match_deterministic_dataset():
@@ -52,3 +55,117 @@ def test_seed_demo_scenarios_present():
         assert failed_run is not None
     finally:
         db.close()
+
+
+def _by_ref(db, model, ref):
+    return db.scalar(select(model).where(model.public_ref == ref))
+
+
+def test_seed_scenario_s1_odometer_regression_return():
+    """S1: BK-DEMO-RETURN on MO-024 is an active booking ready for a return with a
+    below-canonical odometer reading, using the vehicle's own current odometer."""
+    db = SessionLocal()
+    try:
+        reset_and_seed(db)
+        booking = _by_ref(db, Booking, "BK-DEMO-RETURN")
+        vehicle = _by_ref(db, Vehicle, "MO-024")
+        assert booking is not None and vehicle is not None
+        assert booking.vehicle_id == vehicle.id
+        assert booking.status == "active"
+        assert booking.end_odometer_km is None
+        # A demo return reading must sit below the vehicle's canonical odometer to
+        # reproduce the odometer-regression anomaly deterministically.
+        assert vehicle.odometer_km > 0
+    finally:
+        db.close()
+
+
+def test_seed_scenario_s2_duplicate_customer_pair():
+    """S2: CUS-0012/CUS-0178 form a possible-duplicate pair with a matching open issue."""
+    db = SessionLocal()
+    try:
+        reset_and_seed(db)
+        primary = _by_ref(db, Customer, "CUS-0012")
+        duplicate = _by_ref(db, Customer, "CUS-0178")
+        assert primary is not None and duplicate is not None
+        assert primary.email == duplicate.email
+        assert duplicate.merged_into_customer_id is None
+
+        issue = _by_ref(db, DataQualityIssue, "DQ-DEMO-DUPLICATE")
+        assert issue is not None
+        assert issue.rule_type == "possible_duplicate_customer"
+        assert issue.status == "open"
+        related = issue.evidence_json.get("related_refs", [])
+        assert "CUS-0012" in related or "CUS-0178" in related
+    finally:
+        db.close()
+
+
+def test_seed_scenario_s4_booking_overlap():
+    """S4: MO-016 carries two overlapping reservations plus a matching open issue."""
+    db = SessionLocal()
+    try:
+        reset_and_seed(db)
+        vehicle = _by_ref(db, Vehicle, "MO-016")
+        booking_a = _by_ref(db, Booking, "BK-DEMO-OVERLAP-A")
+        booking_b = _by_ref(db, Booking, "BK-DEMO-OVERLAP-B")
+        assert vehicle is not None and booking_a is not None and booking_b is not None
+        assert booking_a.vehicle_id == vehicle.id
+        assert booking_b.vehicle_id == vehicle.id
+        assert booking_a.starts_at < booking_b.ends_at
+        assert booking_b.starts_at < booking_a.ends_at
+
+        issue = _by_ref(db, DataQualityIssue, "DQ-DEMO-OVERLAP")
+        assert issue is not None
+        assert issue.rule_type == "booking_overlap"
+        assert issue.status == "open"
+    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."""
+    db = SessionLocal()
+    try:
+        reset_and_seed(db)
+        failed = db.scalar(
+            select(OutboxEvent).where(
+                OutboxEvent.event_id == "00000000-0000-4000-8000-000000000020"
+            )
+        )
+        assert failed is not None
+        assert failed.delivery_status == "failed"
+        assert failed.attempts >= 1
+        assert failed.last_error
+    finally:
+        db.close()
+
+
+def test_seed_dates_are_anchored_to_reset_moment():
+    """Every reset shifts seeded dates by (real today - authored anchor), so scenario
+    bookings stay 'today'/'near-future' relative to whenever the reset actually ran,
+    instead of decaying back to the fixed 2026-08-01 authoring date."""
+    db = SessionLocal()
+    try:
+        result = reset_and_seed(db)
+        today = datetime.now(UTC).date()
+        assert result.anchor_date == today
+
+        shift = today - SEED_AUTHORED_ANCHOR
+        booking = _by_ref(db, Booking, "BK-DEMO-RETURN")
+        assert booking is not None
+        # Authored ends_at was 2026-08-01T09:00Z; after shifting it must land on the
+        # real reset date, not the frozen authoring date (unless shift is exactly zero).
+        assert booking.ends_at.date() == today or shift.days == 0
+
+        marker = db.scalar(
+            select(AuditEvent)
+            .where(AuditEvent.action == "demo_data_seeded")
+            .order_by(AuditEvent.occurred_at.desc())
+        )
+        assert marker is not None
+        assert marker.metadata_json["anchor_date"] == today.isoformat()
+        assert marker.metadata_json["seed_authored_anchor"] == SEED_AUTHORED_ANCHOR.isoformat()
+    finally:
+        db.close()