Prompt: Create Unified Protocol Buffer Definitions

Objective

Create the complete protobuf definitions for the unified gRPC bridge that supports both tools and variables with streaming capabilities.

Context

You need to create a .proto file that defines all messages and services for the unified bridge. This protocol will be the foundation for all client-server communication.

Requirements

Service Definition

Create a BridgeService with the following RPC methods:

1. ExecuteTool - Execute a tool (existing functionality)
2. RegisterVariable - Register a new variable
3. GetVariable - Get a variable’s current value
4. SetVariable - Update a variable’s value
5. ListVariables - List all variables in a session
6. WatchVariables - Stream variable updates (server streaming)
7. GetSession - Get session information
8. Heartbeat - Keep-alive mechanism

Message Definitions

Core Messages

• Variable - Complete variable representation
• VariableType - Enum for all supported types
• VariableValue - Wrapper using protobuf Any
• VariableConstraints - Type-specific constraints
• VariableMetadata - Additional variable information

Request/Response Messages

• Define request and response messages for each RPC method
• Include session_id in all requests
• Support batch operations where appropriate

Streaming Messages

• WatchVariablesRequest - Subscribe to variables
• VariableUpdate - Streamed update message

Type System

Support these types with proper serialization:

• float, integer, string, boolean (basic types)
• choice (enumeration with allowed values)
• module (DSPy module selection)
• embedding (vector representation)
• tensor (multi-dimensional arrays)

Implementation Steps

1. Create the proto file:

   # Location: snakepit/priv/protos/bridge_service.proto
   

2. Define the service:

   service BridgeService {
     // Tool execution (existing)
     rpc ExecuteTool(ExecuteToolRequest) returns (ExecuteToolResponse);
   
     // Variable management (new)
     rpc RegisterVariable(RegisterVariableRequest) returns (RegisterVariableResponse);
     rpc GetVariable(GetVariableRequest) returns (GetVariableResponse);
     rpc SetVariable(SetVariableRequest) returns (SetVariableResponse);
     rpc ListVariables(ListVariablesRequest) returns (ListVariablesResponse);
   
     // Streaming (new)
     rpc WatchVariables(WatchVariablesRequest) returns (stream VariableUpdate);
   
     // Session management
     rpc GetSession(GetSessionRequest) returns (GetSessionResponse);
     rpc Heartbeat(HeartbeatRequest) returns (HeartbeatResponse);
   }
   

3. Define core messages with proper Any usage:

   import "google/protobuf/any.proto";
   import "google/protobuf/timestamp.proto";
   
   message Variable {
     string id = 1;
     string name = 2;
     VariableType type = 3;
     google.protobuf.Any value = 4;  // JSON-encoded for custom types
     VariableConstraints constraints = 5;
     VariableMetadata metadata = 6;
     int32 version = 7;
   }
   

4. Implement type safety:

   • Use oneof for constraint types
   • Define clear serialization rules
   • Include validation hints

5. Add streaming support:

   message VariableUpdate {
     string variable_id = 1;
     Variable variable = 2;
     google.protobuf.Any old_value = 3;
     string update_source = 4;
     map<string, string> update_metadata = 5;
     google.protobuf.Timestamp timestamp = 6;
     string update_type = 7; // "value_change", "constraint_change", "deleted"
   }
   

Validation Checklist

• All existing tool functionality is preserved
• Variable CRUD operations are complete
• Streaming is properly defined
• Type system is comprehensive
• Session management is included
• Backward compatibility is maintained
• Comments document JSON encoding for Any fields

Example Usage Pattern

After implementation, the protocol should support:

# Python server
async def watch_variables(request, context):
    for update in variable_changes:
        yield VariableUpdate(...)

# Elixir client  
stream = Stub.watch_variables(channel, request)
Enum.each(stream, fn update -> 
  handle_update(update)
end)

Files to Create/Modify

1. Create: snakepit/priv/protos/bridge_service.proto
2. Update: snakepit/mix.exs (if needed for protobuf compilation)
3. Create: snakepit/priv/protos/README.md (document the protocol)

Next Steps

After creating the protobuf definitions:

1. Compile them for both Python and Elixir
2. Proceed to implement the Python server (next prompt)
3. Update the Elixir client to use new protocol