Add Extended Agent Card support: provider, dispatcher, transports, and serializer

benchmarks/bench_agent_card.cpp

@@ -2,7 +2,7 @@
 
 #include <benchmark/benchmark.h>
 
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/protojson.h"
 #include "a2a/server/rest_server_transport.h"
 #include "bench_common.h"

benchmarks/bench_common.h

@@ -11,7 +11,7 @@
 #include <unordered_map>
 #include <utility>
 
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/protocol_bindings.h"
 #include "a2a/core/protojson.h"
 #include "a2a/core/result.h"

examples/apps/auth_policy_server/main.cpp

@@ -8,7 +8,7 @@
 
 #include "a2a/client/client.h"
 #include "a2a/client/http_json_transport.h"
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/url_utils.h"
 #include "a2a/server/agent_executor.h"
 #include "a2a/server/dispatcher.h"

examples/apps/hello_agent/main.cpp

@@ -8,7 +8,7 @@
 
 #include "a2a/client/client.h"
 #include "a2a/client/http_json_transport.h"
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/url_utils.h"
 #include "a2a/server/agent_executor.h"
 #include "a2a/server/dispatcher.h"

examples/apps/json_rpc_server/main.cpp

@@ -8,7 +8,7 @@
 
 #include "a2a/client/client.h"
 #include "a2a/client/json_rpc_transport.h"
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/url_utils.h"
 #include "a2a/server/agent_executor.h"
 #include "a2a/server/dispatcher.h"

examples/apps/rest_server/main.cpp

@@ -8,7 +8,7 @@
 
 #include "a2a/client/client.h"
 #include "a2a/client/http_json_transport.h"
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/url_utils.h"
 #include "a2a/server/agent_executor.h"
 #include "a2a/server/dispatcher.h"

examples/apps/streaming_server/main.cpp

@@ -8,7 +8,7 @@
 
 #include "a2a/client/client.h"
 #include "a2a/client/http_json_transport.h"
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
 #include "a2a/core/url_utils.h"
 #include "a2a/server/agent_executor.h"
 #include "a2a/server/dispatcher.h"

include/a2a/client/client.h

@@ -21,6 +21,7 @@
 #include <vector>
 
 #include "a2a/client/call_options.h"
+#include "a2a/core/non_copyable.h"
 #include "a2a/core/result.h"
 #include "a2a/v1/a2a.pb.h"
 
@@ -72,7 +73,7 @@ class StreamObserver {
   virtual void OnCompleted() = 0;
 };
 
-class StreamHandle final {
+class StreamHandle final : private core::NonCopyable {
  public:
   struct State final {
     std::atomic<bool> cancel_requested{false};
@@ -82,8 +83,6 @@ class StreamHandle final {
   };
 
   StreamHandle() = delete;
-  StreamHandle(const StreamHandle&) = delete;
-  StreamHandle& operator=(const StreamHandle&) = delete;
   StreamHandle(StreamHandle&&) noexcept;
   StreamHandle& operator=(StreamHandle&&) noexcept;
   ~StreamHandle();

include/a2a/core/agent_card_builder.h → include/a2a/core/agent_card/agent_card_builder.h

@@ -22,6 +22,7 @@ class AgentCardBuilder final {
   AgentCardBuilder& AddDefaultInputMode(std::string_view mode);
   AgentCardBuilder& AddDefaultOutputMode(std::string_view mode);
   AgentCardBuilder& WithPushNotifications(bool enabled);
+  AgentCardBuilder& WithExtendedAgentCard(bool enabled);
   AgentCardBuilder& AddExtension(std::string_view uri, bool required, std::string_view description = {});
 
   struct InterfaceSpec final {

include/a2a/core/agent_card/agent_card_provider.h

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Vladimir Pavlov <mistervvp@outlook.com> (https://github.com/MisterVVP)
+
+#pragma once
+
+#include <optional>
+#include <string>
+#include <unordered_map>
+
+#include "a2a/core/non_copyable.h"
+#include "a2a/core/result.h"
+#include "a2a/v1/a2a.pb.h"
+
+namespace a2a::core {
+
+struct AgentCardRequestContext final {
+  std::optional<std::string> remote_address;
+  std::unordered_map<std::string, std::string> client_headers;
+  std::unordered_map<std::string, std::string> auth_metadata;
+};
+
+class AgentCardProvider : private NonCopyableOrMovable {
+ public:
+  AgentCardProvider() = default;
+  virtual ~AgentCardProvider() = default;
+
+  [[nodiscard]] virtual Result<lf::a2a::v1::AgentCard> GetExtendedAgentCard(
+      const AgentCardRequestContext& context) const = 0;
+};
+
+class StaticAgentCardProvider final : public AgentCardProvider {
+ public:
+  StaticAgentCardProvider() = default;
+  explicit StaticAgentCardProvider(std::optional<lf::a2a::v1::AgentCard> extended_agent_card);
+
+  [[nodiscard]] Result<lf::a2a::v1::AgentCard> GetExtendedAgentCard(
+      const AgentCardRequestContext& context) const override;
+
+ private:
+  std::optional<lf::a2a::v1::AgentCard> extended_agent_card_;
+};
+
+}  // namespace a2a::core

include/a2a/core/core.h

@@ -3,7 +3,8 @@
 
 #pragma once
 
-#include "a2a/core/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_builder.h"
+#include "a2a/core/agent_card/agent_card_provider.h"
 #include "a2a/core/error.h"
 #include "a2a/core/extensions.h"
 #include "a2a/core/protojson.h"

include/a2a/core/non_copyable.h

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Vladimir Pavlov <mistervvp@outlook.com> (https://github.com/MisterVVP)
+
+#pragma once
+
+namespace a2a::core {
+
+class NonCopyable {
+ public:
+  NonCopyable(const NonCopyable&) = delete;
+  NonCopyable& operator=(const NonCopyable&) = delete;
+
+ protected:
+  constexpr NonCopyable() noexcept = default;
+  constexpr NonCopyable(NonCopyable&&) noexcept = default;
+  constexpr NonCopyable& operator=(NonCopyable&&) noexcept = default;
+  ~NonCopyable() = default;
+};
+
+class NonCopyableOrMovable {
+ public:
+  NonCopyableOrMovable(const NonCopyableOrMovable&) = delete;
+  NonCopyableOrMovable& operator=(const NonCopyableOrMovable&) = delete;
+  NonCopyableOrMovable(NonCopyableOrMovable&&) = delete;
+  NonCopyableOrMovable& operator=(NonCopyableOrMovable&&) = delete;
+
+ protected:
+  constexpr NonCopyableOrMovable() noexcept = default;
+  ~NonCopyableOrMovable() = default;
+};
+
+}  // namespace a2a::core

include/a2a/core/protocol_methods.h

@@ -17,6 +17,7 @@ inline constexpr std::string_view kCreateTaskPushNotificationConfig = "CreateTas
 inline constexpr std::string_view kGetTaskPushNotificationConfig = "GetTaskPushNotificationConfig";
 inline constexpr std::string_view kListTaskPushNotificationConfigs = "ListTaskPushNotificationConfigs";
 inline constexpr std::string_view kDeleteTaskPushNotificationConfig = "DeleteTaskPushNotificationConfig";
+inline constexpr std::string_view kGetExtendedAgentCard = "GetExtendedAgentCard";
 inline constexpr std::string_view kPushNotificationConfigsSegment = "/pushNotificationConfigs";
 
 }  // namespace a2a::core::protocol_methods

include/a2a/server/agent_card/agent_card_serializer.h

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Vladimir Pavlov <mistervvp@outlook.com> (https://github.com/MisterVVP)
+
+#pragma once
+
+#include <google/protobuf/struct.pb.h>
+
+#include "a2a/core/result.h"
+#include "a2a/v1/a2a.pb.h"
+
+namespace a2a::server {
+
+[[nodiscard]] core::Result<google::protobuf::Struct> BuildNormalizedAgentCard(const lf::a2a::v1::AgentCard& agent_card,
+                                                                              bool include_legacy_transport_fields);
+
+[[nodiscard]] core::Result<google::protobuf::Value> BuildAgentCardJsonValue(const lf::a2a::v1::AgentCard& agent_card,
+                                                                            bool include_legacy_transport_fields);
+
+}  // namespace a2a::server

include/a2a/server/dispatch_types.h

@@ -25,20 +25,22 @@ enum class DispatcherOperation : std::uint8_t {
   kGetTaskPushNotificationConfig,
   kListTaskPushNotificationConfigs,
   kDeleteTaskPushNotificationConfig,
+  kGetExtendedAgentCard,
 };
 
 struct DispatchRequest final {
   DispatcherOperation operation = DispatcherOperation::kSendMessage;
   std::variant<lf::a2a::v1::SendMessageRequest, lf::a2a::v1::GetTaskRequest, ListTasksRequest,
                lf::a2a::v1::CancelTaskRequest, lf::a2a::v1::TaskPushNotificationConfig,
                lf::a2a::v1::GetTaskPushNotificationConfigRequest, lf::a2a::v1::ListTaskPushNotificationConfigsRequest,
-               lf::a2a::v1::DeleteTaskPushNotificationConfigRequest>
+               lf::a2a::v1::DeleteTaskPushNotificationConfigRequest, lf::a2a::v1::GetExtendedAgentCardRequest>
       payload = ListTasksRequest{};
 };
 
-using DispatchPayload = std::variant<lf::a2a::v1::SendMessageResponse, std::unique_ptr<ServerStreamSession>,
-                                     lf::a2a::v1::Task, ListTasksResponse, lf::a2a::v1::TaskPushNotificationConfig,
-                                     lf::a2a::v1::ListTaskPushNotificationConfigsResponse, std::monostate>;
+using DispatchPayload =
+    std::variant<lf::a2a::v1::SendMessageResponse, std::unique_ptr<ServerStreamSession>, lf::a2a::v1::Task,
+                 ListTasksResponse, lf::a2a::v1::TaskPushNotificationConfig,
+                 lf::a2a::v1::ListTaskPushNotificationConfigsResponse, lf::a2a::v1::AgentCard, std::monostate>;
 
 class DispatchResponse final {
  public:
@@ -52,6 +54,8 @@ class DispatchResponse final {
   explicit DispatchResponse(const lf::a2a::v1::TaskPushNotificationConfig& payload) : payload_(payload) {}
   explicit DispatchResponse(lf::a2a::v1::TaskPushNotificationConfig&& payload) : payload_(std::move(payload)) {}
   explicit DispatchResponse(const lf::a2a::v1::ListTaskPushNotificationConfigsResponse& payload) : payload_(payload) {}
+  explicit DispatchResponse(const lf::a2a::v1::AgentCard& payload) : payload_(payload) {}
+  explicit DispatchResponse(lf::a2a::v1::AgentCard&& payload) : payload_(std::move(payload)) {}
   explicit DispatchResponse(lf::a2a::v1::ListTaskPushNotificationConfigsResponse&& payload)
       : payload_(std::move(payload)) {}
   DispatchResponse() : payload_(std::monostate{}) {}

include/a2a/server/dispatcher.h

@@ -7,6 +7,7 @@
 #include <shared_mutex>
 #include <vector>
 
+#include "a2a/core/agent_card/agent_card_provider.h"
 #include "a2a/core/result.h"
 #include "a2a/server/agent_executor.h"
 #include "a2a/server/dispatch_types.h"
@@ -18,7 +19,10 @@ namespace a2a::server {
 class Dispatcher final {
  public:
   explicit Dispatcher(AgentExecutor* executor);
+  explicit Dispatcher(AgentExecutor* executor, std::shared_ptr<core::AgentCardProvider> agent_card_provider);
   explicit Dispatcher(AgentExecutor* executor, std::vector<std::shared_ptr<ServerInterceptor>> interceptors);
+  Dispatcher(AgentExecutor* executor, std::vector<std::shared_ptr<ServerInterceptor>> interceptors,
+             std::shared_ptr<core::AgentCardProvider> agent_card_provider);
 
   [[nodiscard]] core::Result<DispatchResponse> Dispatch(const DispatchRequest& request, RequestContext& context) const;
   void AddInterceptor(std::shared_ptr<ServerInterceptor> interceptor);
@@ -28,6 +32,7 @@ class Dispatcher final {
                             const core::Result<DispatchResponse>& result) const;
 
   AgentExecutor* executor_ = nullptr;
+  std::shared_ptr<core::AgentCardProvider> agent_card_provider_;
   mutable std::shared_mutex interceptor_mutex_;
   std::vector<std::shared_ptr<ServerInterceptor>> interceptors_;
 };

include/a2a/server/grpc_server_transport.h

@@ -18,7 +18,7 @@
 namespace a2a::server {
 
 struct GrpcServerTransportOptions final {
-  std::vector<std::string> required_extensions;
+  std::vector<std::string> required_extensions = {};
 };
 
 class GrpcServerTransport final : public lf::a2a::v1::A2AService::Service {

include/a2a/server/json_rpc_server_transport.h

@@ -24,7 +24,7 @@ struct JsonRpcServerTransportOptions final {
   bool require_version_header = true;
   std::size_t default_list_tasks_page_size = 50;
   std::size_t max_list_tasks_page_size = 100;
-  std::vector<std::string> required_extensions;
+  std::vector<std::string> required_extensions = {};
 };
 
 class JsonRpcServerTransport final {

include/a2a/server/rest_server_transport.h

@@ -46,13 +46,14 @@ struct RestServerTransportOptions final {
   bool require_version_header = true;
   bool include_legacy_transport_fields = true;
   std::optional<AgentCardCacheSettings> agent_card_cache_settings;
-  std::vector<std::string> required_extensions;
+  std::vector<std::string> required_extensions = {};
 };
 
 class RestServerTransport final {
  public:
   static constexpr std::string_view kAgentCardPath = "/.well-known/agent-card.json";
   static constexpr std::string_view kLegacyAgentCardPath = "/.well-known/agent.json";
+  static constexpr std::string_view kExtendedAgentCardPath = "/extendedAgentCard";
 
   RestServerTransport(Dispatcher* dispatcher, lf::a2a::v1::AgentCard agent_card,
                       RestServerTransportOptions options = {});
@@ -63,11 +64,13 @@ class RestServerTransport final {
   [[nodiscard]] core::Result<RestRequest> BuildRestRequest(const HttpServerRequest& request) const;
   [[nodiscard]] core::Result<void> ValidateVersionHeader(const HttpServerRequest& request) const;
   [[nodiscard]] core::Result<HttpServerResponse> HandleAgentCard(const HttpServerRequest& request) const;
+  [[nodiscard]] core::Result<HttpServerResponse> HandleExtendedAgentCard(const HttpServerRequest& request) const;
   [[nodiscard]] static HttpServerResponse ToHttpResponse(const RestResponse& response,
                                                          const std::vector<std::string>& activated_extensions);
 
   static std::string NormalizeBasePath(std::string_view path);
 
+  Dispatcher* dispatcher_ = nullptr;
   RestTransport transport_;
   lf::a2a::v1::AgentCard agent_card_;
   RestServerTransportOptions options_;

include/a2a/server/stores/postgres_common.h

@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "a2a/core/error.h"
+#include "a2a/core/non_copyable.h"
 #include "a2a/server/stores/store_factory.h"
 
 typedef struct pg_conn PGconn;
@@ -55,11 +56,9 @@ class PostgresConnectionPool final {
  public:
   explicit PostgresConnectionPool(std::string connection_string, std::size_t size = kDefaultPostgresConnectionPoolSize);
 
-  class Lease final {
+  class Lease final : private core::NonCopyable {
    public:
     Lease(PostgresConnectionPool* pool, PgConnection connection);
-    Lease(const Lease&) = delete;
-    Lease& operator=(const Lease&) = delete;
     Lease(Lease&& other) noexcept;
     Lease& operator=(Lease&& other) noexcept = delete;
     ~Lease();

include/a2a/server/stores/store_factory.h

@@ -6,6 +6,7 @@
 #include <memory>
 #include <string>
 
+#include "a2a/core/non_copyable.h"
 #include "a2a/core/result.h"
 #include "a2a/server/push_notification_store.h"
 #include "a2a/server/tasks/in_memory_task_store.h"
@@ -28,13 +29,9 @@ struct StoreBundle final {
   std::unique_ptr<PushNotificationStore> push_store;
 };
 
-class StoreFactory {
+class StoreFactory : private core::NonCopyableOrMovable {
  public:
   StoreFactory() = default;
-  StoreFactory(const StoreFactory&) = delete;
-  StoreFactory& operator=(const StoreFactory&) = delete;
-  StoreFactory(StoreFactory&&) = delete;
-  StoreFactory& operator=(StoreFactory&&) = delete;
   virtual ~StoreFactory() = default;
 
   [[nodiscard]] virtual StoreBackendKind backend_kind() const noexcept = 0;

include/a2a/server/stream_response_coroutine.h

@@ -8,11 +8,12 @@
 #include <optional>
 #include <utility>
 
+#include "a2a/core/non_copyable.h"
 #include "a2a/v1/a2a.pb.h"
 
 namespace a2a::server {
 
-class StreamResponseCoroutine final {
+class StreamResponseCoroutine final : private core::NonCopyable {
  public:
   struct promise_type final {
     [[nodiscard]] StreamResponseCoroutine get_return_object() {
@@ -32,9 +33,6 @@ class StreamResponseCoroutine final {
   };
 
   StreamResponseCoroutine() = default;
-  StreamResponseCoroutine(const StreamResponseCoroutine&) = delete;
-  StreamResponseCoroutine& operator=(const StreamResponseCoroutine&) = delete;
-
   StreamResponseCoroutine(StreamResponseCoroutine&& other) noexcept : handle_(std::exchange(other.handle_, {})) {}
   StreamResponseCoroutine& operator=(StreamResponseCoroutine&& other) noexcept {
     if (this != &other) {