fix(webhooks): correct type annotations for extract_webhook_result_data and payload builders

src/adcp/webhooks.py

@@ -40,6 +40,7 @@
 )
 from google.protobuf.json_format import MessageToDict, ParseDict
 from google.protobuf.struct_pb2 import Value
+from pydantic import BaseModel as PydanticBaseModel
 
 from adcp.server.idempotency.backends import MemoryBackend as MemoryBackend
 from adcp.server.idempotency.webhook_dedup import WebhookDedupStore as WebhookDedupStore
@@ -57,7 +58,6 @@
 )
 from adcp.types import GeneratedTaskStatus
 from adcp.types.base import AdCPBaseModel
-from adcp.types.generated_poc.core.async_response_data import AdcpAsyncResponseData
 from adcp.webhook_receiver import (
     LegacyHmacFallback,
     VerifiedSignerLike,
@@ -86,7 +86,7 @@ def generate_webhook_idempotency_key() -> str:
 def create_mcp_webhook_payload(
     task_id: str,
     status: GeneratedTaskStatus | str,
-    result: AdcpAsyncResponseData | dict[str, Any] | None = None,
+    result: PydanticBaseModel | dict[str, Any] | None = None,
     timestamp: datetime | None = None,
     task_type: str | None = None,
     operation_id: str | None = None,
@@ -107,7 +107,7 @@ def create_mcp_webhook_payload(
         status: Current task status
         task_type: Optionally type of AdCP operation (e.g., "get_products", "create_media_buy")
         timestamp: When the webhook was generated (defaults to current UTC time)
-        result: Task-specific payload (AdCP response data)
+        result: Task-specific payload — any Pydantic model or plain dict
         operation_id: Client-generated identifier the buyer embedded in the
             webhook URL when registering push-notification config. Publishers
             MUST echo this back in the payload so buyers correlate notifications
@@ -358,7 +358,7 @@ def sign_legacy_webhook(
     return signature_headers, body_bytes
 
 
-def extract_webhook_result_data(webhook_payload: dict[str, Any]) -> AdcpAsyncResponseData | None:
+def extract_webhook_result_data(webhook_payload: dict[str, Any]) -> dict[str, Any] | None:
     """
     Extract result data from webhook payload (MCP or A2A format).
 
@@ -376,8 +376,8 @@ def extract_webhook_result_data(webhook_payload: dict[str, Any]) -> AdcpAsyncRes
         webhook_payload: Raw webhook dictionary from HTTP request (JSON-deserialized)
 
     Returns:
-        AdcpAsyncResponseData union type containing the extracted AdCP response, or None
-        if no result present. For A2A webhooks, unwraps data from artifacts/message parts
+        dict[str, Any] containing the extracted AdCP response data, or None if no
+        result is present. For A2A webhooks, unwraps data from artifacts/message parts
         structure. For MCP webhooks, returns the result field directly.
 
     Examples:
@@ -464,8 +464,8 @@ def extract_webhook_result_data(webhook_payload: dict[str, Any]) -> AdcpAsyncRes
                 data = part["data"]
                 # Unwrap {"response": {...}} wrapper if present (A2A convention)
                 if isinstance(data, dict) and "response" in data and len(data) == 1:
-                    return cast(AdcpAsyncResponseData, data["response"])
-                return cast(AdcpAsyncResponseData, data)
+                    return cast(dict[str, Any], data["response"])
+                return cast(dict[str, Any], data)
 
         return None
 
@@ -485,20 +485,20 @@ def extract_webhook_result_data(webhook_payload: dict[str, Any]) -> AdcpAsyncRes
                     data = part["data"]
                     # Unwrap {"response": {...}} wrapper if present
                     if isinstance(data, dict) and "response" in data and len(data) == 1:
-                        return cast(AdcpAsyncResponseData, data["response"])
-                    return cast(AdcpAsyncResponseData, data)
+                        return cast(dict[str, Any], data["response"])
+                    return cast(dict[str, Any], data)
 
             return None
 
     # MCP format: result field directly
-    return cast(AdcpAsyncResponseData | None, webhook_payload.get("result"))
+    return cast(dict[str, Any] | None, webhook_payload.get("result"))
 
 
 def create_a2a_webhook_payload(
     task_id: str,
     status: GeneratedTaskStatus,
     context_id: str,
-    result: AdcpAsyncResponseData | dict[str, Any],
+    result: PydanticBaseModel | dict[str, Any],
     timestamp: datetime | None = None,
 ) -> Task | TaskStatusUpdateEvent:
     """
@@ -517,7 +517,7 @@ def create_a2a_webhook_payload(
         status: Current task status
         context_id: Session/conversation identifier (required by A2A protocol)
         timestamp: When the webhook was generated (defaults to current UTC time)
-        result: Task-specific payload (AdCP response data)
+        result: Task-specific payload — any Pydantic model or plain dict
 
     Returns:
         Task object for terminated statuses, TaskStatusUpdateEvent for intermediate statuses
@@ -529,17 +529,18 @@ def create_a2a_webhook_payload(
         >>>
         >>> task = create_a2a_webhook_payload(
         ...     task_id="task_123",
+        ...     context_id="ctx_123",
         ...     status=GeneratedTaskStatus.completed,
         ...     result={"products": [...]},
-        ...     message="Found 5 products"
         ... )
         >>> # task is a Task object with artifacts containing the result
 
         Create a working status update:
         >>> event = create_a2a_webhook_payload(
         ...     task_id="task_456",
+        ...     context_id="ctx_456",
         ...     status=GeneratedTaskStatus.working,
-        ...     message="Processing 3 of 10 items"
+        ...     result={"current_step": "processing", "percentage": 30},
         ... )
         >>> # event is a TaskStatusUpdateEvent with status.message
 
@@ -590,7 +591,7 @@ def create_a2a_webhook_payload(
     # Build parts for the message/artifact.
     parts: list[pb.Part] = []
 
-    # Convert AdcpAsyncResponseData to dict if it's a Pydantic model
+    # Convert Pydantic model to dict if needed
     if hasattr(result, "model_dump"):
         result_dict: dict[str, Any] = result.model_dump(mode="json")
     else:

tests/test_import_layering.py

@@ -57,7 +57,6 @@
         "src/adcp/utils/preview_cache.py",
         "src/adcp/webhook_receiver.py",
         "src/adcp/webhook_sender.py",
-        "src/adcp/webhooks.py",
     }
 )
 

tests/test_webhook_handling.py

@@ -12,10 +12,18 @@
 from a2a.types import TaskState, TaskStatusUpdateEvent
 from google.protobuf.json_format import MessageToDict as _MessageToDict
 
+from pydantic import BaseModel
+
 from adcp.client import ADCPClient
 from adcp.exceptions import ADCPWebhookSignatureError
+from adcp.types import GeneratedTaskStatus
 from adcp.types.core import AgentConfig, Protocol, TaskStatus
-from adcp.webhooks import extract_webhook_result_data, get_adcp_signed_headers_for_webhook
+from adcp.webhooks import (
+    create_a2a_webhook_payload,
+    create_mcp_webhook_payload,
+    extract_webhook_result_data,
+    get_adcp_signed_headers_for_webhook,
+)
 from tests.a2a_compat_shim import (
     Artifact,
     DataPart,
@@ -1186,6 +1194,79 @@ def test_extract_from_mcp_with_error_response(self):
         assert result["errors"][0]["code"] == "INTERNAL_ERROR"
 
 
+class _DeliveryResponse(BaseModel):
+    """Minimal Pydantic model for testing the BaseModel branch in payload builders."""
+
+    media_buy_id: str
+    buyer_ref: str
+    packages: list[str] = []
+
+
+class TestWebhookPayloadBuilderPydanticModel:
+    """Pydantic BaseModel inputs to create_mcp_webhook_payload / create_a2a_webhook_payload.
+
+    Regression guard for the PydanticBaseModel branch (model_dump path inside
+    both builders). Prior to the fix these functions were typed to accept only
+    AdcpAsyncResponseData, which is a narrow discriminated union — passing any
+    other BaseModel subclass required a type: ignore comment even though the
+    runtime hasattr(result, "model_dump") guard handled it correctly.
+    """
+
+    def test_create_mcp_payload_accepts_pydantic_model(self):
+        model = _DeliveryResponse(media_buy_id="mb_1", buyer_ref="ref_1")
+        payload = create_mcp_webhook_payload(
+            task_id="task_1",
+            task_type="media_buy_delivery",
+            status=GeneratedTaskStatus.completed,
+            result=model,
+        )
+        assert payload["result"] == {"media_buy_id": "mb_1", "buyer_ref": "ref_1", "packages": []}
+
+    def test_create_mcp_payload_pydantic_model_serialized_as_json(self):
+        model = _DeliveryResponse(media_buy_id="mb_2", buyer_ref="ref_2", packages=["pkg_a"])
+        payload = create_mcp_webhook_payload(
+            task_id="task_2",
+            task_type="media_buy_delivery",
+            status=GeneratedTaskStatus.completed,
+            result=model,
+        )
+        result = payload["result"]
+        assert isinstance(result, dict)
+        assert result["packages"] == ["pkg_a"]
+
+    def test_create_a2a_payload_accepts_pydantic_model_completed(self):
+        from a2a.types import Task as A2ATask
+
+        model = _DeliveryResponse(media_buy_id="mb_3", buyer_ref="ref_3")
+        task = create_a2a_webhook_payload(
+            task_id="task_3",
+            context_id="ctx_3",
+            status=GeneratedTaskStatus.completed,
+            result=model,
+        )
+        assert isinstance(task, A2ATask)
+        task_dict = _MessageToDict(task, preserving_proto_field_name=False)
+        extracted = extract_webhook_result_data(task_dict)
+        assert extracted is not None
+        assert extracted["media_buy_id"] == "mb_3"
+
+    def test_create_a2a_payload_accepts_pydantic_model_working(self):
+        from a2a.types import TaskStatusUpdateEvent as A2AEvent
+
+        model = _DeliveryResponse(media_buy_id="mb_4", buyer_ref="ref_4")
+        event = create_a2a_webhook_payload(
+            task_id="task_4",
+            context_id="ctx_4",
+            status=GeneratedTaskStatus.working,
+            result=model,
+        )
+        assert isinstance(event, A2AEvent)
+        event_dict = _MessageToDict(event, preserving_proto_field_name=False)
+        extracted = extract_webhook_result_data(event_dict)
+        assert extracted is not None
+        assert extracted["media_buy_id"] == "mb_4"
+
+
 # Load official AdCP HMAC test vectors from fixtures.
 # Source: adcontextprotocol/adcp PR #2478 (merged 2026-04-20), which pins the
 # canonical on-wire JSON form (compact separators) and adds rejection vectors