diff --git a/docs/CostCheckProtocol.md b/docs/CostCheckProtocol.md
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+# OSVauco Cost Check Protocol
+
+> Implements OSVauco-NMTMD-GCOS § Cost Management — sist oppdatert 2026-05-23
+
+## Når skal 09-cost-check.sh kjøres?
+
+| Situasjon | Handling |
+|---|---|
+| Før du starter arbeid for dagen | Kjør for se hva som fortsatt kjører fra forrige sesjon |
+| Agenten booter og `MEMORY_ENGINE_NAME` er tom | Kjør for sjekke om instans allerede finnes |
+| Før teardown | Kjør for bekrefte hva som vil bli slettet |
+| Mistanke om uventet kostnad | Kjør umiddelbart |
+
+## Kjør protokollen
+
+```bash
+cd ~/OSVauco
+source .env
+bash infrastructure/09-cost-check.sh
+```
+
+## Hva den sjekker
+
+| Punkt | Ressurs | Koster løpende? |
+|---|---|---|
+| [1] | Cloud Run services | Ja, per request + CPU |
+| [2] | Reasoning Engines / Memory Bank | **Ja, kontinuerlig** |
+| [3] | Artifact Registry | Litt, per GB lagret |
+| [4] | RAG Corpora | Minimal |
+| [5] | GCS Buckets | Minimal |
+| [6] | Budget alerts | Sjekker at varsler er aktive |
+
+## Memory Bank — spesialregel
+
+Memory Bank (Vertex AI Reasoning Engine) **slettes ikke av `03-teardown.sh`** og
+faktureres kontinuerlig:
+
+- **$0.0994/vCPU-time**
+- **$0.0105/GiB-time**
+- Gratis tier: 180 000 vCPU-sekunder/mnd
+
+Hvis `09-cost-check.sh` punkt [2] viser aktive instanser du ikke trenger:
+
+```bash
+gcloud ai reasoning-engines delete ENGINE_NAME \
+  --project=$PROJECT_ID --region=$REGION --quiet
+```
+
+## Agentprotokoll
+
+Alle agenter som bruker Memory Bank skal ved boot sjekke:
+
+```python
+import os
+if not os.getenv("MEMORY_ENGINE_NAME"):
+    raise RuntimeError(
+        "MEMORY_ENGINE_NAME ikke satt i .env. "
+        "Kjør: source .env && bash infrastructure/09-cost-check.sh "
+        "for å se eksisterende instanser."
+    )
+```
+
+## Teardown-regel (obligatorisk)
+
+```bash
+# Hver kveld:
+source .env
+bash infrastructure/09-cost-check.sh   # se hva som kjører
+bash infrastructure/03-teardown.sh      # rydd ned Cloud Run + IAM
+# Memory Bank: slett manuelt hvis ikke i bruk
+```
diff --git a/infrastructure/09-cost-check.sh b/infrastructure/09-cost-check.sh
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+#!/usr/bin/env bash
+# 09-cost-check.sh — Daily cost and resource audit protocol
+# Run before teardown OR when agents boot and MEMORY_ENGINE_NAME is unset
+# Usage: source .env && bash infrastructure/09-cost-check.sh
+# OSVauco-NMTMD-GCOS — Implements cost protocol from CostManagementRules.md
+
+set -euo pipefail
+
+: "${PROJECT_ID:?Set PROJECT_ID in .env}"
+: "${REGION:?Set REGION in .env}"
+
+echo "=== 09: OSVauco Cost & Resource Audit ==="
+echo "  Project : ${PROJECT_ID}"
+echo "  Region  : ${REGION}"
+echo "  Time    : $(date '+%Y-%m-%d %H:%M %Z')"
+echo "=========================================="
+echo ""
+
+# ── 1. Cloud Run services ──────────────────────────────────────────────────
+echo "[1] Cloud Run services (active = billing):"
+gcloud run services list \
+  --project="${PROJECT_ID}" \
+  --region="${REGION}" \
+  --format="table(name,status.url,status.conditions[0].status)" 2>/dev/null \
+  || echo "  (none found or API not enabled)"
+echo ""
+
+# ── 2. Vertex AI Reasoning Engines (Memory Bank instances) ────────────────
+echo "[2] Vertex AI Reasoning Engines / Memory Bank instances:"
+echo "    COST: ~\$0.0994/vCPU-hour + \$0.0105/GiB-hour after free tier"
+ENGINES=$(gcloud ai reasoning-engines list \
+  --project="${PROJECT_ID}" \
+  --region="${REGION}" \
+  --format="table(name,displayName,createTime)" 2>/dev/null || echo "")
+
+if [[ -z "$ENGINES" || "$ENGINES" == *"Listed 0 items"* ]]; then
+  echo "  ✓ No active Reasoning Engine / Memory Bank instances found."
+else
+  echo "$ENGINES"
+  echo ""
+  echo "  ⚠️  ACTIVE INSTANCES FOUND — these cost money continuously."
+  echo "  To delete manually:"
+  echo "    gcloud ai reasoning-engines delete ENGINE_NAME \\"
+  echo "      --project=${PROJECT_ID} --region=${REGION} --quiet"
+fi
+echo ""
+
+# ── 3. Artifact Registry repositories ────────────────────────────────────
+echo "[3] Artifact Registry repositories:"
+gcloud artifacts repositories list \
+  --project="${PROJECT_ID}" \
+  --location="${REGION}" \
+  --format="table(name,format,sizeBytes)" 2>/dev/null \
+  || echo "  (none found)"
+echo ""
+
+# ── 4. RAG Corpora (NOT deleted by teardown) ──────────────────────────────
+echo "[4] Vertex AI RAG Corpora (NOT deleted by teardown — manual cleanup only):"
+gcloud ai rag-corpora list \
+  --project="${PROJECT_ID}" \
+  --region="${REGION}" \
+  --format="table(name,displayName,createTime)" 2>/dev/null \
+  || echo "  (none found or API not enabled)"
+echo ""
+
+# ── 5. GCS Buckets ────────────────────────────────────────────────────────
+echo "[5] GCS Buckets (NOT deleted by teardown):"
+gcloud storage buckets list \
+  --project="${PROJECT_ID}" \
+  --format="table(name,location,storageClass)" 2>/dev/null \
+  || echo "  (none found)"
+echo ""
+
+# ── 6. Budget alert status ────────────────────────────────────────────────
+echo "[6] Billing budget alerts:"
+BILLING_ACCOUNT_ID="${BILLING_ACCOUNT_ID:-}"
+if [[ -n "$BILLING_ACCOUNT_ID" ]]; then
+  gcloud billing budgets list \
+    --billing-account="${BILLING_ACCOUNT_ID}" \
+    --format="table(displayName,amount.specifiedAmount.units,thresholdRules.len())" 2>/dev/null \
+    || echo "  (none found or billing API not enabled)"
+else
+  echo "  (BILLING_ACCOUNT_ID not set in .env — skipping)"
+fi
+echo ""
+
+# ── Summary ───────────────────────────────────────────────────────────────
+echo "=========================================="
+echo "  AUDIT COMPLETE — $(date '+%Y-%m-%d %H:%M %Z')"
+echo ""
+echo "  OBLIGATORISK: Kjør teardown på slutten av arbeidsdagen:"
+echo "    source .env && bash infrastructure/03-teardown.sh"
+echo ""
+echo "  Reasoning Engines / Memory Bank må slettes MANUELT hvis ikke i bruk."
+echo "  Se punkt [2] ovenfor."
+echo "=========================================="