docs(rag): add domain model and original research input

chunking/docs/adr/0006-qdrant-deployment.md

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+# ADR 0006: Qdrant Deployment
+
+## Status
+
+Accepted
+
+## Context
+
+The system is migrating from ChromaDB to Qdrant. Deployment must work fully on-premises with no external dependencies, given the risk of prolonged internet blackouts (up to 90 days).
+
+## Decision
+
+Deploy **Qdrant as a Docker container** on-premises.
+
+### Configuration
+
+```yaml
+# docker-compose.yml
+services:
+  qdrant:
+    image: qdrant/qdrant:latest
+    ports:
+      - "6333:6333"  # REST API
+      - "6334:6334"  # gRPC API
+    volumes:
+      - ./qdrant_storage:/qdrant/storage
+    environment:
+      - QDRANT__LOG_LEVEL=INFO
+    restart: unless-stopped
+```
+
+### Why Docker
+- **Isolation** — consistent environment, no dependency conflicts
+- **Portability** — easy to move between servers
+- **Simplicity** — single container, no orchestration complexity
+- **Persistence** — volume mount ensures data survives container restarts
+- **No external dependencies** — fully on-prem
+
+### Collection Configuration
+
+Single collection with named vectors:
+```python
+from qdrant_client import QdrantClient
+from qdrant_client.models import Distance, VectorParams
+
+client = QdrantClient(host="localhost", port=6333)
+
+client.create_collection(
+    collection_name="insurance_docs",
+    vectors_config={
+        "openai": VectorParams(size=3072, distance=Distance.COSINE),
+        "nomic": VectorParams(size=768, distance=Distance.COSINE),
+    }
+)
+```
+
+## Consequences
+
+### Positive
+- **Fully on-prem** — works during internet blackouts
+- **Simple operations** — single container to manage
+- **Fast access** — no network latency to external services
+- **Data sovereignty** — all data stays in your infrastructure
+
+### Negative
+- **Manual backups** — must implement backup strategy
+- **Single point of failure** — no built-in replication (consider Qdrant cluster if HA needed)
+- **Hardware dependent** — performance tied to host resources
+
+### Neutral
+- Storage requirements depend on corpus size and vector dimensions
+- May need to tune Qdrant's HNSW parameters for optimal recall/speed trade-off
+- Consider resource limits in Docker for predictable performance
+
+## Backup Strategy
+
+- Regular snapshots: `qdrant-cli snapshot create`
+- Volume backup: backup `./qdrant_storage` directory
+- Test restore procedure before production deployment
+
+## Alternatives Considered
+
+1. **Qdrant Cloud** — requires internet, not viable
+2. **Kubernetes deployment** — adds complexity, not needed for single-node setup
+3. **Standalone binary** — Docker provides better isolation and process management