Turn Message -> str into a resuable utility method

Change-Id: I50f020880af3f216ece3792d97cf31e00e00bf4c

Author: mikeas1

src/a2a/server/agent_execution/context.py

@@ -7,6 +7,7 @@
     Task,
     TextPart,
 )
+from a2a.utils import get_message_text
 from a2a.utils.errors import ServerError
 
 
@@ -48,11 +49,7 @@ def get_user_input(self, delimiter='\n') -> str:
         if not self._params:
             return ''
 
-        parts = []
-        for part in self._params.message.parts:
-            if isinstance(part.root, TextPart):
-                parts.append(part.root.text)
-        return delimiter.join(parts)
+        return get_message_text(self._params.message, delimiter)
 
     def attach_related_task(self, task: Task):
         self._related_tasks.append(task)

src/a2a/utils/__init__.py

@@ -4,14 +4,20 @@
     build_text_artifact,
     create_task_obj,
 )
-from a2a.utils.message import new_agent_text_message
+from a2a.utils.message import (
+    get_message_text,
+    get_text_parts,
+    new_agent_text_message,
+)
 from a2a.utils.task import new_task
 
 
 __all__ = [
     'append_artifact_to_task',
     'build_text_artifact',
     'create_task_obj',
+    'get_message_text',
+    'get_text_parts',
     'new_agent_text_message',
     'new_task',
     'new_text_artifact',

src/a2a/utils/message.py

@@ -19,3 +19,12 @@ def new_agent_text_message(
         taskId=task_id,
         contextId=context_id,
     )
+
+
+def get_text_parts(parts: list[Part]) -> list[str]:
+    """Return all text parts from a list of parts."""
+    return [part.root.text for part in parts if isinstance(part.root, TextPart)]
+
+
+def get_message_text(message: Message, delimiter='\n') -> str:
+    return delimiter.join(get_text_parts(message.parts))