feat: join audit-storage usage without inventing a booked Scaleway fact

Ingest resource-control's August technical usage, omit nulls, and
reconcile forecast + usage + booked facts. Commissioning month reports
missing_booked_fact instead of 0.00. T05 still waits on the first invoice.

tests/test_exchange.py

@@ -1,3 +1,4 @@
+import json
 from datetime import date, datetime, timezone
 from decimal import Decimal
 from pathlib import Path
@@ -17,6 +18,8 @@ from fin_hub.services.exchange import (
     financial_constraint_projection,
     ingest_planning_evidence,
     ingest_resource_forecast,
+    ingest_resource_usage,
+    reconcile_resource_period,
 )
 from fin_hub.services.ledger import import_csv
 
@@ -341,3 +344,72 @@ def test_exchange_health_exposes_rejection_stale_forecast_and_unattributed_cost(
         "stale_forecast",
         "unattributed_booked_cost",
     }
+
+
+FIXTURES = Path(__file__).parent / "fixtures"
+AUDIT_STORAGE = "resource:platform:audit-storage"
+
+
+def test_audit_storage_usage_omits_nulls_and_does_not_invent_zero_spend(tmp_path: Path):
+    ledger = tmp_path / "ledger.db"
+    payload = json.loads(
+        (FIXTURES / "platform-audit-storage-usage-2026-08.json").read_text()
+    )
+    records = ingest_resource_usage(
+        payload,
+        resource_id=AUDIT_STORAGE,
+        source_evidence_ref="resource-control:data/actuals/2026-08.json",
+        ledger_path=ledger,
+    )
+    assert len(records) == 1
+    names = {measure.name: measure for measure in records[0].measures}
+    assert set(names) == {
+        "database_gb",
+        "stored_gb",
+        "backup_success_pct",
+        "restore_rto_minutes",
+    }
+    assert "infrastructure_eur" not in names
+    assert names["stored_gb"].value == Decimal("0.0066")
+    assert any("gap:infrastructure_eur" in item for item in records[0].source_evidence)
+
+    forecast = {
+        "schema_version": "0.1",
+        "record_type": "forecast",
+        "workload": "platform-pg",
+        "cost_attribution_key": "platform:audit-storage",
+        "provider_id": "scaleway-standard-multi-az",
+        "created_at": "2026-08-10T17:10:00Z",
+        "scenario": "base",
+        "forecast_ref": None,
+        "rows": [
+            {
+                "period": "2026-09",
+                "database_gb": 5,
+                "stored_gb": 180,
+                "wal_gb": 30,
+                "restore_egress_gb": 5,
+                "write_requests": 2500,
+                "read_requests": 1000,
+                "infrastructure_eur": 2.89,
+                "internal_labor_hours": 1,
+                "internal_labor_eur": 60,
+                "total_eur": 62.89,
+            }
+        ],
+    }
+    ingest_resource_forecast(
+        forecast,
+        resource_id=AUDIT_STORAGE,
+        source_evidence_ref="resource-control:data/forecasts/platform-audit-storage",
+        ledger_path=ledger,
+    )
+    august = reconcile_resource_period(
+        resource_id=AUDIT_STORAGE, period="2026-08", ledger_path=ledger
+    )
+    assert august.usage_record_ids
+    assert august.missing_booked_fact is True
+    assert august.booked_effective_amount is None
+    assert august.invented_zero is False
+    health = exchange_health(ledger_path=ledger)
+    assert "usage_without_booked_fact" in {issue.code for issue in health.issues}