feat(helpers): add new_data_part, new_raw_part, and new_url_part helpers

Part.data is google.protobuf.Value in the v1.0 spec, which requires a
non-obvious ParseDict dance to construct from a plain dict. Add
new_data_part() to hide that complexity. Also add new_raw_part() and
new_url_part() to cover the remaining non-text Part variants that had
no helpers, keeping the API consistent with new_text_message() et al.

Author: martimfasantos

src/a2a/helpers/proto_helpers.py

@@ -3,6 +3,10 @@
 import uuid
 
 from collections.abc import Sequence
+from typing import Any
+
+from google.protobuf import struct_pb2
+from google.protobuf.json_format import ParseDict
 
 from a2a.types.a2a_pb2 import (
     Artifact,
@@ -57,6 +61,89 @@ def get_message_text(message: Message, delimiter: str = '\n') -> str:
     return delimiter.join(get_text_parts(message.parts))
 
 
+def new_data_message(
+    data: Any,
+    role: Role = Role.ROLE_AGENT,
+    context_id: str | None = None,
+    task_id: str | None = None,
+) -> Message:
+    """Creates a new message containing a single data Part.
+
+    Args:
+        data: JSON-serializable data to embed (dict, list, str, etc.).
+        role: The role of the message sender (default: ROLE_AGENT).
+        context_id: Optional context ID.
+        task_id: Optional task ID.
+
+    Returns:
+        A Message with a single data Part.
+    """
+    return new_message(
+        parts=[new_data_part(data)],
+        role=role,
+        context_id=context_id,
+        task_id=task_id,
+    )
+
+
+def new_raw_message(  # noqa: PLR0913
+    raw: bytes,
+    media_type: str | None = None,
+    filename: str | None = None,
+    role: Role = Role.ROLE_AGENT,
+    context_id: str | None = None,
+    task_id: str | None = None,
+) -> Message:
+    """Creates a new message containing a single raw bytes Part.
+
+    Args:
+        raw: The raw bytes content.
+        media_type: Optional MIME type (e.g. 'image/png').
+        filename: Optional filename.
+        role: The role of the message sender (default: ROLE_AGENT).
+        context_id: Optional context ID.
+        task_id: Optional task ID.
+
+    Returns:
+        A Message with a single raw Part.
+    """
+    return new_message(
+        parts=[new_raw_part(raw, media_type=media_type, filename=filename)],
+        role=role,
+        context_id=context_id,
+        task_id=task_id,
+    )
+
+
+def new_url_message(  # noqa: PLR0913
+    url: str,
+    media_type: str | None = None,
+    filename: str | None = None,
+    role: Role = Role.ROLE_AGENT,
+    context_id: str | None = None,
+    task_id: str | None = None,
+) -> Message:
+    """Creates a new message containing a single URL Part.
+
+    Args:
+        url: The URL pointing to the file content.
+        media_type: Optional MIME type (e.g. 'image/png').
+        filename: Optional filename.
+        role: The role of the message sender (default: ROLE_AGENT).
+        context_id: Optional context ID.
+        task_id: Optional task ID.
+
+    Returns:
+        A Message with a single URL Part.
+    """
+    return new_message(
+        parts=[new_url_part(url, media_type=media_type, filename=filename)],
+        role=role,
+        context_id=context_id,
+        task_id=task_id,
+    )
+
+
 # --- Artifact Helpers ---
 
 
@@ -90,6 +177,89 @@ def new_text_artifact(
     )
 
 
+def new_data_artifact(
+    name: str,
+    data: Any,
+    description: str | None = None,
+    artifact_id: str | None = None,
+) -> Artifact:
+    """Creates a new Artifact object containing only a single data Part.
+
+    Args:
+        name: The name of the artifact.
+        data: JSON-serializable data to embed (dict, list, str, etc.).
+        description: Optional description.
+        artifact_id: Optional artifact ID (auto-generated if not provided).
+
+    Returns:
+        An Artifact with a single data Part.
+    """
+    return new_artifact(
+        [new_data_part(data)],
+        name,
+        description,
+        artifact_id=artifact_id,
+    )
+
+
+def new_raw_artifact(  # noqa: PLR0913
+    name: str,
+    raw: bytes,
+    media_type: str | None = None,
+    filename: str | None = None,
+    description: str | None = None,
+    artifact_id: str | None = None,
+) -> Artifact:
+    """Creates a new Artifact object containing only a single raw bytes Part.
+
+    Args:
+        name: The name of the artifact.
+        raw: The raw bytes content.
+        media_type: Optional MIME type (e.g. 'image/png').
+        filename: Optional filename.
+        description: Optional description.
+        artifact_id: Optional artifact ID (auto-generated if not provided).
+
+    Returns:
+        An Artifact with a single raw Part.
+    """
+    return new_artifact(
+        [new_raw_part(raw, media_type=media_type, filename=filename)],
+        name,
+        description,
+        artifact_id=artifact_id,
+    )
+
+
+def new_url_artifact(  # noqa: PLR0913
+    name: str,
+    url: str,
+    media_type: str | None = None,
+    filename: str | None = None,
+    description: str | None = None,
+    artifact_id: str | None = None,
+) -> Artifact:
+    """Creates a new Artifact object containing only a single URL Part.
+
+    Args:
+        name: The name of the artifact.
+        url: The URL pointing to the file content.
+        media_type: Optional MIME type (e.g. 'image/png').
+        filename: Optional filename.
+        description: Optional description.
+        artifact_id: Optional artifact ID (auto-generated if not provided).
+
+    Returns:
+        An Artifact with a single URL Part.
+    """
+    return new_artifact(
+        [new_url_part(url, media_type=media_type, filename=filename)],
+        name,
+        description,
+        artifact_id=artifact_id,
+    )
+
+
 def get_artifact_text(artifact: Artifact, delimiter: str = '\n') -> str:
     """Extracts and joins all text content from an Artifact's parts."""
     return delimiter.join(get_text_parts(artifact.parts))
@@ -141,6 +311,62 @@ def new_task(
 # --- Part Helpers ---
 
 
+def new_data_part(data: Any) -> Part:
+    """Creates a Part with structured data (google.protobuf.Value).
+
+    Args:
+        data: JSON-serializable data to embed (dict, list, str, etc.).
+
+    Returns:
+        A Part with the data field set.
+    """
+    return Part(data=ParseDict(data, struct_pb2.Value()))
+
+
+def new_raw_part(
+    raw: bytes,
+    media_type: str | None = None,
+    filename: str | None = None,
+) -> Part:
+    """Creates a Part with raw bytes content.
+
+    Args:
+        raw: The raw bytes content.
+        media_type: Optional MIME type (e.g. 'image/png').
+        filename: Optional filename.
+
+    Returns:
+        A Part with the raw field set.
+    """
+    return Part(
+        raw=raw,
+        media_type=media_type or '',
+        filename=filename or '',
+    )
+
+
+def new_url_part(
+    url: str,
+    media_type: str | None = None,
+    filename: str | None = None,
+) -> Part:
+    """Creates a Part with a URL pointing to file content.
+
+    Args:
+        url: The URL to the file content.
+        media_type: Optional MIME type (e.g. 'image/png').
+        filename: Optional filename.
+
+    Returns:
+        A Part with the url field set.
+    """
+    return Part(
+        url=url,
+        media_type=media_type or '',
+        filename=filename or '',
+    )
+
+
 def get_text_parts(parts: Sequence[Part]) -> list[str]:
     """Extracts text content from all text Parts."""
     return [part.text for part in parts if part.HasField('text')]