LangGraph

Verification notes: Same organization and MIT license family as LangChain. Correction this pass: the a2a flag moves from false to true. LangChain's own current docs confirm LangGraph's Agent Server now exposes a native A2A endpoint at /a2a/{assistant_id}, supporting message/send, message/stream, tasks/get, and agent-card discovery via /.well-known/agent-card.json, requiring langgraph-api>=0.4.21. This is specific to LangGraph's Agent Server — see LangChain for the separate, still-unresolved feature request for A2A support in core LangChain itself. MCP support and open-source status unchanged. Re-checked this pass: no change to MCP or A2A support. LangGraph's Agent Server changelog shows routine platform maintenance since the last check (a dependency security fix for a checkpoint-storage CVE, TTL parameter support on store endpoints, and a streaming fix for remote JS graphs) -- operational hardening rather than a change to protocol support.