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/agent_card_builder.h

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Vladimir Pavlov <mistervvp@outlook.com> (https://github.com/MisterVVP)
+
+#pragma once
+
+#include <string>
+#include <string_view>
+
+#include "a2a/core/error.h"
+#include "a2a/core/protocol_bindings.h"
+#include "a2a/core/result.h"
+#include "a2a/core/version.h"
+#include "a2a/v1/a2a.pb.h"
+
+namespace a2a::core {
+
+class AgentCardBuilder final {
+ public:
+  AgentCardBuilder& SetName(std::string_view name);
+  AgentCardBuilder& SetVersion(std::string_view version);
+  AgentCardBuilder& SetDescription(std::string_view description);
+  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 {
+    std::string_view binding;
+    std::string_view version;
+    std::string_view url;
+  };
+
+  AgentCardBuilder& AddInterface(const InterfaceSpec& spec);
+
+  [[nodiscard]] Result<void> Validate() const;
+  [[nodiscard]] lf::a2a::v1::AgentCard Build() const;
+
+  [[nodiscard]] static AgentCardBuilder RestPreset(std::string_view name, std::string_view url,
+                                                   std::string_view version = Version::kAgentCardVersion);
+  [[nodiscard]] static AgentCardBuilder JsonRpcPreset(std::string_view name, std::string_view url,
+                                                      std::string_view version = Version::kAgentCardVersion);
+  [[nodiscard]] static AgentCardBuilder GrpcPreset(std::string_view name, std::string_view url,
+                                                   std::string_view version = Version::kAgentCardVersion);
+  struct ConformancePresetSpec final {
+    std::string_view rest_url;
+    std::string_view json_rpc_url;
+    std::string_view grpc_url;
+  };
+
+  [[nodiscard]] static AgentCardBuilder ConformancePreset(const ConformancePresetSpec& spec,
+                                                          std::string_view name = "Conformance SUT",
+                                                          std::string_view version = Version::kAgentCardVersion,
+                                                          std::string_view description = "A2A conformance agent");
+
+ private:
+  lf::a2a::v1::AgentCard card_;
+};
+
+}  // namespace a2a::core

include/a2a/core/agent_card/agent_card_provider.h

@@ -0,0 +1,44 @@
+// 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> tenant;
+  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/agent_card_builder.h

@@ -3,57 +3,4 @@
 
 #pragma once
 
-#include <string>
-#include <string_view>
-
-#include "a2a/core/error.h"
-#include "a2a/core/protocol_bindings.h"
-#include "a2a/core/result.h"
-#include "a2a/core/version.h"
-#include "a2a/v1/a2a.pb.h"
-
-namespace a2a::core {
-
-class AgentCardBuilder final {
- public:
-  AgentCardBuilder& SetName(std::string_view name);
-  AgentCardBuilder& SetVersion(std::string_view version);
-  AgentCardBuilder& SetDescription(std::string_view description);
-  AgentCardBuilder& AddDefaultInputMode(std::string_view mode);
-  AgentCardBuilder& AddDefaultOutputMode(std::string_view mode);
-  AgentCardBuilder& WithPushNotifications(bool enabled);
-  AgentCardBuilder& AddExtension(std::string_view uri, bool required, std::string_view description = {});
-
-  struct InterfaceSpec final {
-    std::string_view binding;
-    std::string_view version;
-    std::string_view url;
-  };
-
-  AgentCardBuilder& AddInterface(const InterfaceSpec& spec);
-
-  [[nodiscard]] Result<void> Validate() const;
-  [[nodiscard]] lf::a2a::v1::AgentCard Build() const;
-
-  [[nodiscard]] static AgentCardBuilder RestPreset(std::string_view name, std::string_view url,
-                                                   std::string_view version = Version::kAgentCardVersion);
-  [[nodiscard]] static AgentCardBuilder JsonRpcPreset(std::string_view name, std::string_view url,
-                                                      std::string_view version = Version::kAgentCardVersion);
-  [[nodiscard]] static AgentCardBuilder GrpcPreset(std::string_view name, std::string_view url,
-                                                   std::string_view version = Version::kAgentCardVersion);
-  struct ConformancePresetSpec final {
-    std::string_view rest_url;
-    std::string_view json_rpc_url;
-    std::string_view grpc_url;
-  };
-
-  [[nodiscard]] static AgentCardBuilder ConformancePreset(const ConformancePresetSpec& spec,
-                                                          std::string_view name = "Conformance SUT",
-                                                          std::string_view version = Version::kAgentCardVersion,
-                                                          std::string_view description = "A2A conformance agent");
-
- private:
-  lf::a2a::v1::AgentCard card_;
-};
-
-}  // namespace a2a::core
+#include "a2a/core/agent_card/agent_card_builder.h"

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/http_constants.h

@@ -21,6 +21,7 @@ inline constexpr char kContentTypeParameterSeparator = ';';
 
 inline constexpr std::string_view kMethodGet = "GET";
 inline constexpr std::string_view kMethodPost = "POST";
+inline constexpr std::string_view kMethodDelete = "DELETE";
 
 inline constexpr std::string_view kHttpScheme = "http://";
 inline constexpr std::string_view kHttpsScheme = "https://";

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

@@ -19,4 +19,22 @@ inline constexpr std::string_view kListTaskPushNotificationConfigs = "ListTaskPu
 inline constexpr std::string_view kDeleteTaskPushNotificationConfig = "DeleteTaskPushNotificationConfig";
 inline constexpr std::string_view kPushNotificationConfigsSegment = "/pushNotificationConfigs";
 
+struct GetExtendedAgentCardMethodName final {
+  static constexpr std::string_view kCanonical = "GetExtendedAgentCard";
+  static constexpr std::string_view kJsonRpcAlias = "a2a.getExtendedAgentCard";
+
+  constexpr operator std::string_view() const noexcept { return kCanonical; }
+};
+
+inline constexpr GetExtendedAgentCardMethodName kGetExtendedAgentCard{};
+
+constexpr bool operator==(std::string_view actual, GetExtendedAgentCardMethodName) noexcept {
+  return actual == GetExtendedAgentCardMethodName::kCanonical ||
+         actual == GetExtendedAgentCardMethodName::kJsonRpcAlias;
+}
+
+constexpr bool operator==(GetExtendedAgentCardMethodName method, std::string_view actual) noexcept {
+  return actual == method;
+}
+
 }  // namespace a2a::core::protocol_methods

include/a2a/core/protocol_paths.h

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2026 Vladimir Pavlov <mistervvp@outlook.com> (https://github.com/MisterVVP)
+
+#pragma once
+
+#include <string_view>
+
+namespace a2a::core::protocol_paths {
+
+inline constexpr std::string_view kAgentCard = "/.well-known/agent-card.json";
+inline constexpr std::string_view kLegacyAgentCard = "/.well-known/agent.json";
+inline constexpr std::string_view kExtendedAgentCard = "/extendedAgentCard";
+inline constexpr std::string_view kWellKnownPrefix = "/.well-known/";
+
+}  // namespace a2a::core::protocol_paths

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{}) {}