Summary

Hardens gRPC service security across three critical areas:

1. Connection Pool Fix (CRITICAL)

• Replaced all conn.close() calls with factory.release(conn) to return connections to the pool
• Fixed pool exhaustion bug: after 20 requests the server became unable to serve any new requests
• 53 conn.close() calls replaced across auth interceptor, data_service, and credit_class_service

2. Scope Enforcement

• Added require_scope() calls to all 54 RPC handlers
• Read methods require read scopes, write methods require write scopes
• Financial mutations (bridge, marketplace) require additional scope checks
• Any valid API key now has fine-grained access control instead of god-mode

3. TLS Support

• Configurable via GRPC_TLS_CERT and GRPC_TLS_KEY env vars
• Falls back to insecure transport with warning when not configured

4. Health Watch Fix

• Watch RPC now keeps stream open with periodic SERVING updates
• Fixed violation of gRPC health protocol

Tests

26 tests covering scope enforcement, pool resilience, TLS configuration, and health watch behavior.