fix(jsonrpc): add steam_send_timeout param for configurable SSE timeouts to JSONRPCApplication, A2AStarletteApplication, and A2AFastAPIApplication to resolve timeout issues

Author: devesh1011

src/a2a/server/apps/jsonrpc/fastapi_app.py

@@ -78,6 +78,7 @@ def __init__(  # noqa: PLR0913
         ]
         | None = None,
         max_content_length: int | None = 10 * 1024 * 1024,  # 10MB
+        stream_send_timeout: float | None = None,
     ) -> None:
         """Initializes the A2AFastAPIApplication.
 
@@ -97,6 +98,8 @@ def __init__(  # noqa: PLR0913
               call context.
             max_content_length: The maximum allowed content length for incoming
               requests. Defaults to 10MB. Set to None for unbounded maximum.
+            stream_send_timeout: The timeout in seconds for sending events in default timeout. Set to a larger value or None to disable for
+              long-running agents.
         """
         if not _package_fastapi_installed:
             raise ImportError(
@@ -112,6 +115,7 @@ def __init__(  # noqa: PLR0913
             card_modifier=card_modifier,
             extended_card_modifier=extended_card_modifier,
             max_content_length=max_content_length,
+            stream_send_timeout=stream_send_timeout,
         )
 
     def add_routes_to_app(

src/a2a/server/apps/jsonrpc/jsonrpc_app.py

@@ -184,6 +184,7 @@ def __init__(  # noqa: PLR0913
         ]
         | None = None,
         max_content_length: int | None = 10 * 1024 * 1024,  # 10MB
+        stream_send_timeout: float | None = None,
     ) -> None:
         """Initializes the JSONRPCApplication.
 
@@ -203,6 +204,10 @@ def __init__(  # noqa: PLR0913
               call context.
             max_content_length: The maximum allowed content length for incoming
               requests. Defaults to 10MB. Set to None for unbounded maximum.
+            stream_send_timeout: The timeout in seconds for sending events in
+              streaming responses. Defaults to None, which uses Starlette's
+              default timeout. Set to a larger value or None to disable for
+              long-running agents.
         """
         if not _package_starlette_installed:
             raise ImportError(
@@ -222,6 +227,7 @@ def __init__(  # noqa: PLR0913
         )
         self._context_builder = context_builder or DefaultCallContextBuilder()
         self._max_content_length = max_content_length
+        self.stream_send_timeout = stream_send_timeout
 
     def _generate_error_response(
         self, request_id: str | int | None, error: JSONRPCError | A2AError
@@ -540,8 +546,14 @@ async def event_generator(
                 async for item in stream:
                     yield {'data': item.root.model_dump_json(exclude_none=True)}
 
+            send_timeout = context.state.get(
+                'stream_send_timeout', self.stream_send_timeout
+            )
+
             return EventSourceResponse(
-                event_generator(handler_result), headers=headers
+                event_generator(handler_result),
+                headers=headers,
+                send_timeout=send_timeout,
             )
         if isinstance(handler_result, JSONRPCErrorResponse):
             return JSONResponse(

src/a2a/server/apps/jsonrpc/starlette_app.py

@@ -60,6 +60,7 @@ def __init__(  # noqa: PLR0913
         ]
         | None = None,
         max_content_length: int | None = 10 * 1024 * 1024,  # 10MB
+        stream_send_timeout: float | None = None,
     ) -> None:
         """Initializes the A2AStarletteApplication.
 
@@ -79,6 +80,10 @@ def __init__(  # noqa: PLR0913
               call context.
             max_content_length: The maximum allowed content length for incoming
               requests. Defaults to 10MB. Set to None for unbounded maximum.
+            stream_send_timeout: The timeout in seconds for sending events in
+              streaming responses. Defaults to None, which uses Starlette's
+              default timeout. Set to a larger value or None to disable for
+              long-running agents.
         """
         if not _package_starlette_installed:
             raise ImportError(
@@ -94,6 +99,7 @@ def __init__(  # noqa: PLR0913
             card_modifier=card_modifier,
             extended_card_modifier=extended_card_modifier,
             max_content_length=max_content_length,
+            stream_send_timeout=stream_send_timeout,
         )
 
     def routes(