Performance tuning done

docs/communication-environment.md

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+# Communication Environment
+
+Runtime credentials must be supplied through the deployment environment or a
+secret manager. Passwords and private keys must not be committed to this
+repository.
+
+## Cloud service
+
+```text
+DB_HOST=192.168.0.111
+DB_PORT=5432
+DB_NAME=cygnus
+DB_USER=postgres
+DB_PASSWORD=<secret>
+DB_SSL=false
+
+REDIS_HOST=192.168.0.111
+REDIS_PORT=7901
+REDIS_PASSWORD=<secret>
+REDIS_SSL=false
+
+CYGNUS_SECURITY_ENABLED=false
+CYGNUS_JWT_ISSUER_URI=https://auth.example.com
+CYGNUS_JWT_AUDIENCE=cygnus-cloud-api
+```
+
+Set `CYGNUS_SECURITY_ENABLED=true` only after the authorization server/JWK
+issuer is available. Production database, Redis, token, and API traffic should
+use encrypted transport.
+
+## On-premises application cache
+
+```text
+REDIS_HOST=192.168.0.111
+REDIS_PORT=7901
+REDIS_PASSWORD=<secret>
+REDIS_SSL=false
+CYGNUS_CACHE_PREFIX=cygnus:onprem
+CYGNUS_CACHE_TTL_SECONDS=600
+```
+
+The on-premises cache connects lazily and treats Redis failures as cache misses,
+so Redis downtime does not prevent the legacy application from starting.