TaskPushNotificationConfig model doesn't match v1 spec's flat structure

[darrelmiller]

Summary

The SDK's TaskPushNotificationConfig uses a two-class nested structure inherited from v0.3, but the v1 spec defines a single flat message.

Spec definition (a2a.proto)

message TaskPushNotificationConfig {
  string tenant = 1;
  string id = 2;
  string task_id = 3;
  string url = 4 [(google.api.field_behavior) = REQUIRED];
  string token = 5;
  AuthenticationInfo authentication = 6;
}

One flat message - no nested PushNotificationConfig.

Current SDK structure

// Wrapper
public sealed class TaskPushNotificationConfig {
    public string Id { get; set; }
    public string TaskId { get; set; }
    public PushNotificationConfig PushNotificationConfig { get; set; } // nested
    public string? Tenant { get; set; }
}

// Nested config (not in v1 spec)
public sealed class PushNotificationConfig {
    public string? Id { get; set; }      // duplicated
    public string Url { get; set; }
    public AuthenticationInfo? Authentication { get; set; }
    public string? Token { get; set; }
}

Discrepancies

Field	Spec	SDK
Structure	Flat message	Two nested classes
id	Once, on TaskPushNotificationConfig	Duplicated on both classes
url	Direct field	Nested under PushNotificationConfig.Url
token	Direct field	Nested under PushNotificationConfig.Token
authentication	Direct field	Nested under PushNotificationConfig.Authentication

Additionally, CreateTaskPushNotificationConfigRequest wraps a PushNotificationConfig Config property, but the spec's CreateTaskPushNotificationConfig RPC takes a TaskPushNotificationConfig directly as its request message.

The ListTaskPushNotificationConfigsRequest (spec) vs ListTaskPushNotificationConfigRequest (SDK) also differs in pluralization (Configs vs Config).

Proposed fix

• Flatten TaskPushNotificationConfig to match the spec (move url, token, authentication up, remove nested PushNotificationConfig)
• Remove or deprecate the standalone PushNotificationConfig class
• Update CreateTaskPushNotificationConfigRequest to align with the spec's RPC signature
• Fix pluralization of ListTaskPushNotificationConfigRequest to ListTaskPushNotificationConfigsRequest
• This is a breaking change for the push notification API surface

References

• Spec proto: https://github.com/a2aproject/A2A/blob/main/specification/a2a.proto
• Spec Section 9.4.7 (JSON-RPC push notification methods)
• Spec Section 11.3.3 (HTTP+JSON push notification endpoints)