Draft: Streamable Http

[xavierleune]

Q	A
Bug fix?	no
New feature?	yes
Docs?	Todo
Issues	Fix #166 #5
License	MIT

This pull request is currently a draft / work in progress (before getting away from keyboard) to enable support of Streamable Http. There is still a lot to do, but it's kinda working. Quick demo with a tool call that sends a bunch of notif before sending the result: youtube.

Key points:

• I don't use the Server for streamable http, it's quite impractical as it hides too much the internal logic
• JsonRpcHandler now handle one message at a time, as batching has been dropped
• I think we should separate message encoding / decoding and message handling, it might improve the workflow
• The *Handler Api needs a rework to work well with streams, it's currently only a quick poc in ToolCallHandler and it's kinda ugly

Todo:

• Support for Session Management
• Basic support for Resumability and Redelivery
• Full support for Resumability and Redelivery
• Dropped support for Json-Rpc batching
• Better mapping between Json RPC schema and Symfony\AI\McpSdk\Message (with separation between Server sent objects and Client sent objects)
• Tests
• Docs

Technical stuff:

• Split Message handling and message encoding
• Cleaner Api for *Handler
• Param for session duration
• Cleaner support for notifications sent by the client
• Simplify session management (drop left-over SessionIdentifierResolver and so)
• CS / Copyright / ...