Feature: Create protobuf specification for plugin framework to support gRPC and multi-language support.

[terylt]

ContextForge Protobuf Schemas

Language-agnostic schema definitions for the ContextForge plugin framework.

Why Protobuf?

Enable plugin development in multiple languages (Python, Rust, Go, Java) while maintaining a single source of truth for data structures. Protobuf provides:

• Cross-language compatibility - Write plugins in Rust/Go, integrate with Python gateway
• Wire protocol - Efficient serialization for external plugin communication
• Schema documentation - Single canonical definition with field requirements
• Type safety - Generated code with strong typing for all languages

Quick Start

# Generate protobuf Python classes
cd protobufs/plugins/schemas
./generate_python.sh

# Run tests
pytest tests/unit/mcpgateway/plugins/framework/generated/

Architecture

Pydantic models (mcpgateway/plugins/framework/models.py) are the canonical Python implementation.

Protobuf schemas (protobufs/plugins/schemas/) enable cross-language support (Rust, Go, etc.).

Conversion methods bridge the two:

# Pydantic → Protobuf
proto_msg = pydantic_model.model_dump_pb()

# Protobuf → Pydantic
pydantic_model = GlobalContext.model_validate_pb(proto_msg)

Schema Structure

protobufs/plugins/schemas/mcpgateway/plugins/framework/generated/
├── types.proto       # Shared types (GlobalContext, PluginViolation, etc.)
├── tools.proto          # Tool hook payloads
├── prompts.proto        # Prompt hook payloads
├── resources.proto      # Resource hook payloads
└── agents.proto         # Agent hook payloads

Field Requirements

Protos document field requirements with comments:

• // REQUIRED - Must be set
• // OPTIONAL - Can be omitted
• // OPTIONAL - defaults to X - Default value specified

Usage

Python (Pydantic):

from mcpgateway.plugins.framework.models import GlobalContext

ctx = GlobalContext(request_id="req-123", user="alice")

Cross-language (Protobuf):

# Serialize for external plugin
proto_ctx = ctx.model_dump_pb()
serialized = proto_ctx.SerializeToString()

# Send over wire, receive response...

# Deserialize
from contextforge.plugins.common import types_pb2
proto_ctx = types_pb2.GlobalContext()
proto_ctx.ParseFromString(serialized)
ctx = GlobalContext.model_validate_pb(proto_ctx)

Other languages: Generate code from protos using standard tools:

# Rust
protoc --rust_out=. protobufs/plugins/schemas/mcpgateway/plugins/framework/generated/types.proto

# Go
protoc --go_out=. protobufs/plugins/schemas/mcpgateway/plugins/framework/generated/types.proto

Key Features

✅ Pydantic models remain canonical (validation, type safety, Python-native)
✅ Protobuf for wire protocol and cross-language serialization
✅ Lazy loading - protobuf only imported when needed
✅ Follows Pydantic conventions (model_dump_pb(), model_validate_pb())