docs(federation): operator setup + migration guides (FED-M1-11) (#480)

docs/federation/SETUP.md

@@ -0,0 +1,119 @@
+# Federated Tier Setup Guide
+
+## What is the federated tier?
+
+The federated tier is designed for multi-user and multi-host deployments. It consists of PostgreSQL 17 with pgvector extension (for embeddings and RAG), Valkey for distributed task queueing and caching, and a shared configuration across multiple Mosaic gateway instances. Use this tier when running Mosaic in production or when scaling beyond a single-host deployment.
+
+## Prerequisites
+
+- Docker and Docker Compose installed
+- Ports 5433 (PostgreSQL) and 6380 (Valkey) available on your host (or adjust environment variables)
+- At least 2 GB free disk space for data volumes
+
+## Start the federated stack
+
+Run the federated overlay:
+
+```bash
+docker compose -f docker-compose.federated.yml --profile federated up -d
+```
+
+This starts PostgreSQL 17 with pgvector and Valkey 8. The pgvector extension is created automatically on first boot.
+
+Verify the services are running:
+
+```bash
+docker compose -f docker-compose.federated.yml ps
+```
+
+Expected output shows `postgres-federated` and `valkey-federated` both healthy.
+
+## Configure mosaic for federated tier
+
+Create or update your `mosaic.config.json`:
+
+```json
+{
+  "tier": "federated",
+  "database": "postgresql://mosaic:mosaic@localhost:5433/mosaic",
+  "queue": "redis://localhost:6380"
+}
+```
+
+If you're using environment variables instead:
+
+```bash
+export DATABASE_URL="postgresql://mosaic:mosaic@localhost:5433/mosaic"
+export REDIS_URL="redis://localhost:6380"
+```
+
+## Verify health
+
+Run the health check:
+
+```bash
+mosaic gateway doctor
+```
+
+Expected output (green):
+
+```
+Tier: federated  Config: mosaic.config.json
+  ✓ postgres         localhost:5433       (42ms)
+  ✓ valkey           localhost:6380       (8ms)
+  ✓ pgvector         (embedded)           (15ms)
+```
+
+For JSON output (useful in CI/automation):
+
+```bash
+mosaic gateway doctor --json
+```
+
+## Troubleshooting
+
+### Port conflicts
+
+**Symptom:** `bind: address already in use`
+
+**Fix:** Stop the base dev stack first:
+
+```bash
+docker compose down
+docker compose -f docker-compose.federated.yml --profile federated up -d
+```
+
+Or change the host port with an environment variable:
+
+```bash
+PG_FEDERATED_HOST_PORT=5434 VALKEY_FEDERATED_HOST_PORT=6381 \
+  docker compose -f docker-compose.federated.yml --profile federated up -d
+```
+
+### pgvector extension error
+
+**Symptom:** `ERROR: could not open extension control file`
+
+**Fix:** pgvector is created at first boot. Check logs:
+
+```bash
+docker compose -f docker-compose.federated.yml logs postgres-federated | grep -i vector
+```
+
+If missing, exec into the container and create it manually:
+
+```bash
+docker exec <postgres-federated-id> psql -U mosaic -d mosaic -c "CREATE EXTENSION vector;"
+```
+
+### Valkey connection refused
+
+**Symptom:** `Error: connect ECONNREFUSED 127.0.0.1:6380`
+
+**Fix:** Check service health:
+
+```bash
+docker compose -f docker-compose.federated.yml logs valkey-federated
+```
+
+If Valkey is running, verify your firewall allows 6380. On macOS, Docker Desktop may require binding to `host.docker.internal` instead of `localhost`.