Show HN: Radkit, A2A focused rust agents SDK (github.com)

Radkit is a new Rust agent SDK built from the ground up to natively implement the A2A (Agent-to-Agent) protocol, not as an afterthought like many other frameworks. It provides multi-provider LLM support today (Anthropic Claude, Google Gemini; OpenAI planned), a function-calling tool system, and built-in task management tools (update_status, save_artifact). Radkit streams protocol-compliant A2A events (TaskStatusUpdate, TaskArtifactUpdate) and enforces a clear task lifecycle (Submitted → Working → [InputRequired/AuthRequired] → Completed/Failed), enabling real-time observability and orchestration of agent workflows. The library emphasizes atomic, thread-safe operations for messages, artifacts, and status updates which is critical for concurrent agent ecosystems. Technically, Radkit includes MCP tool integration, a capability-based ToolContext for secure tool access, and three-tier state isolation (app/user/session). Example code shows a Tokio-based streaming API that creates an Anthropic LLM-backed agent, sends a message, and reacts to streamed A2A events to capture status and artifacts. Current release is 0.0.1 (WIP) with core A2A architecture complete; planned additions include A2A server/client modes (HTTP/gRPC), persistent storage backends (Postgres/Redis), WebSocket streaming, and OpenAPI tool generation. Radkit is Apache 2.0 licensed, targeting robust, interoperable agent-to-agent ecosystems in production Rust environments.