AGNTCY/SLIM support

[destroyersrt]

SLIM Protocol Support - Secure Low-latency Interactive Messaging

This PR adds support for the AGNTCY SLIM protocol, enabling agents to communicate via gRPC-based point-to-point messaging with persistent connections. SLIM provides an alternative to HTTP-based A2A communication, offering lower latency and more efficient bi-directional streaming.

🎯 Key Changes

SLIM Protocol Integration

• Implemented SLIMProtocol adapter (protocols/slim/adapter.py) using official slim-bindings SDK
• Point-to-point messaging with session management and automatic retries
• Personal inbox channels for each agent (agent-{id}-inbox)
• Async message handling with concurrent session support
• Automatic protocol selection (SLIM preferred when available)

Protocol Router Enhancements

• Updated ProtocolRouter to launch protocols concurrently
• SLIM protocol prioritized when supported by both sender and receiver
• Dynamic endpoint generation for multi-protocol agents
• Fallback URL construction for SLIM identifiers (slim://{agent_id})

Configuration & Setup

• Added environment variables for SLIM configuration (SLIM_ENABLED, SLIM_NODE_URL)
• Docker Compose setup for SLIM control plane and data plane services
• SLIM submodule integration (agntcy/slim.git)
• Updated dependencies: slim-bindings, grpcio, protobuf

Agent Bridge Updates

• Enhanced AgentBridge to handle SLIM URL format (slim://{agent_id})
• Protocol-aware routing with fallback logic
• Support for both HTTP endpoints (A2A) and SLIM identifiers
• Improved agent discovery with multi-protocol support

Testing Infrastructure

• Added test_sender.py and test_receiver.py for SLIM protocol validation
• Demonstrates point-to-point messaging with route setup and session management

📦 Architecture

Agent Communication Flow:
Agent A (sender)
└─> ProtocolRouter.send_message()
└─> SLIMProtocol.send_message()
├─> slim.set_route(target_name)
├─> slim.create_session(PointToPoint)
├─> session.publish(message)
└─> session.get_message() [reply]

Agent B (receiver)  
  └─> SLIMProtocol._listen_for_messages()
      └─> slim.listen_for_session()
          ├─> session.get_message()
          ├─> incoming_handler(message)
          └─> session.publish_to(reply)

🔧 Configuration Example

Enable SLIM in your agent:
nanda = NANDA(
agent_id="my-agent",
agent_logic=my_logic,
protocols={
"a2a": {"enabled": True},
"slim": {
"enabled": True,
"node_url": "grpc://localhost:50051"
}
}
)

Environment Variables:
SLIM_ENABLED=true
SLIM_NODE_URL=grpc://localhost:50051

Docker Compose:
docker-compose up -d # Starts SLIM control plane + data plane

✅ Benefits

• Lower Latency: gRPC-based persistent connections vs HTTP request/response
• Bi-directional Streaming: Full-duplex communication with session support
• Reliability: Built-in retries and timeout handling
• Scalability: Distributed routing via SLIM control plane
• Security: Shared secret authentication (configurable identity providers)
• Flexibility: Automatic fallback to A2A when SLIM unavailable

🚀 Protocol Selection Logic

1. Check if target agent supports SLIM (from registry)
2. If SLIM available → use SLIM protocol
3. Otherwise → fallback to A2A (HTTP)
4. Construct appropriate URL format (slim:// or https://)

📋 Next Steps

• Environment-based shared secret configuration
• MLS encryption support for SLIM sessions
• SLIM connection pooling and reuse
• Metrics and monitoring for SLIM protocol
• Integration tests with both A2A and SLIM agents