SDK CreateTaskPushNotificationConfig uses TaskPushNotificationConfig (flat) as request type; spec defines CreateTaskPushNotificationConfigRequest (nested config)

[zeroasterisk]

Summary

The SDK maps CreateTaskPushNotificationConfig to TaskPushNotificationConfig as the JSON-RPC request type. The A2A v1.0 spec defines a distinct CreateTaskPushNotificationConfigRequest message that wraps the config in a nested config: PushNotificationConfig field. The SDK's flat mapping causes a protocol-level divergence from the spec.

Spec Reference

File: specification/a2a.proto

message CreateTaskPushNotificationConfigRequest {
  string tenant = 1;
  string task_id = 2 [(google.api.field_behavior) = REQUIRED];
  PushNotificationConfig config = 3 [(google.api.field_behavior) = REQUIRED];  // NESTED
}

SDK Implementation

# a2a/server/apps/jsonrpc/jsonrpc_app.py
METHOD_TO_MODEL: dict[str, type] = {
    ...
    'CreateTaskPushNotificationConfig': TaskPushNotificationConfig,  # Wrong type!
    ...
}

The SDK uses TaskPushNotificationConfig (a response/storage type) as the request deserialization target, instead of CreateTaskPushNotificationConfigRequest. The TaskPushNotificationConfig has flat fields {id, task_id, url, token, authentication} while the spec's request type has {task_id, config: PushNotificationConfig{id, url, token}}.

Impact

The SDK accepts a flat {"taskId": "...", "id": "cfg-1", "url": "..."} format, but per spec the correct wire format is {"taskId": "...", "config": {"id": "cfg-1", "url": "..."}}. This means:

1. Spec-compliant clients sending the nested format get -32602
2. The TCK (which sends configId at the wrong level) also gets -32602

Reproduction

# Start any a2a-sdk 1.0.0a0 agent with push notifications capability
TASK_ID=$(curl -s http://localhost:9996 ... | extract_task_id)

# Spec-correct nested format (FAILS with SDK):
curl -X POST http://localhost:9996 -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","method":"CreateTaskPushNotificationConfig","params":{"taskId":"'"$TASK_ID"'","config":{"id":"cfg-1","url":"https://example.com/hook"}},"id":"2"}'
# => -32602: 'config' is not a valid field in TaskPushNotificationConfig

# SDK's flat format (WORKS but not per spec):
curl -X POST http://localhost:9996 -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","method":"CreateTaskPushNotificationConfig","params":{"taskId":"'"$TASK_ID"'","id":"cfg-1","url":"https://example.com/hook"},"id":"2"}'
# => {"result": {"id": "cfg-1", "taskId": "...", "url": "..."}}

Expected vs Actual

• Spec defines: CreateTaskPushNotificationConfig request type = CreateTaskPushNotificationConfigRequest
• SDK uses: TaskPushNotificationConfig (flat, wrong)
• Effect: The SDK JSON-RPC layer doesn't match the v1.0 proto definition for this method

Fix

In jsonrpc_app.py, change the method mapping to use the correct request type and update the handler to extract the nested config from the request:

from a2a.types.a2a_pb2 import CreateTaskPushNotificationConfigRequest
METHOD_TO_MODEL = {
    ...
    'CreateTaskPushNotificationConfig': CreateTaskPushNotificationConfigRequest,
    ...
}

And update set_push_notification_config handler to accept CreateTaskPushNotificationConfigRequest and convert to TaskPushNotificationConfig.

Classification

SDK bug: Wrong request type used for CreateTaskPushNotificationConfig. The SDK should parse CreateTaskPushNotificationConfigRequest (nested) not TaskPushNotificationConfig (flat).

[zeroasterisk]

Closing — the flat TaskPushNotificationConfig structure is correct per spec. PR a2aproject/A2A#1500 merged March 3 and intentionally flattened TaskPushNotificationConfig + PushNotificationConfig into a single flat message. The SDK matches the current spec. Apologies for the noise.