Add Extended Agent Card support: provider, dispatcher, transports, and serializer by MisterVVP · Pull Request #126 · MisterVVP/a2a-cpp

MisterVVP · 2026-06-29T17:33:53Z

Motivation

Introduce support for an "extended agent card" that can be provided dynamically by the server and requested via protocol RPCs and HTTP/JSON-RPC endpoints.
Allow servers to declare support for an extended agent card in the agent card (WithExtendedAgentCard) while optionally configuring a provider that returns the full extended card.
Ensure transports (REST, gRPC, JSON-RPC) and dispatcher plumbing can route GetExtendedAgentCard requests and serialize normalized agent card JSON consistently, including legacy transport compatibility fields when requested.

Description

Added a provider abstraction core::AgentCardProvider and a simple core::StaticAgentCardProvider with GetExtendedAgentCard to supply configured extended cards via include/a2a/core/agent_card/agent_card_provider.h and src/core/agent_card/agent_card_provider.cpp.
Added AgentCardBuilder::WithExtendedAgentCard(bool) in include/a2a/core/agent_card/agent_card_builder.h and implementation in src/core/agent_card/agent_card_builder.cpp to mark capability in built cards.
Added a new protocol method constant core::protocol_methods::kGetExtendedAgentCard and extended dispatch_types/Dispatcher to support DispatcherOperation::kGetExtendedAgentCard and carry lf::a2a::v1::AgentCard in dispatch payloads.
Dispatcher now accepts an optional AgentCardProvider and will call it when handling kGetExtendedAgentCard; errors map to protocol error codes when no provider is configured.
Implemented agent card normalization/serialization helpers in server/agent_card/agent_card_serializer.* to produce normalized JSON and optionally add legacy transport fields.
Exposed an HTTP endpoint (/extendedAgentCard) via RestServerTransport::HandleExtendedAgentCard, and routed GetExtendedAgentCard through JSON-RPC (GetExtendedAgentCard method) and gRPC (GetExtendedAgentCard RPC) transports to the dispatcher.
Updated server code to add new source files to CMake (agent_card_provider, agent_card_serializer, moved agent card builder into agent_card/), and adjusted includes across examples/tests to the new a2a/core/agent_card/ path.
Updated/added unit and integration tests to cover configured and not-configured scenarios and required-extension validation for extended agent card handling (tests/unit/*, tests/integration/grpc_transport_integration_test.cpp, tests/interop/tck_http_sut.cpp).

Testing

Ran unit tests including AgentCardBuilderTest, GrpcServerTransportTest, JsonRpcServerTransportTest, RestServerTransportTest, and ServerDispatcherTest, which were updated to cover configured and missing provider scenarios; all unit tests passed.
Executed the gRPC transport integration test (tests/integration/grpc_transport_integration_test.cpp) after wiring the StaticAgentCardProvider; the integration test passed.
Exercised the TCK SUT example (tests/interop/tck_http_sut.cpp) with the new extended-card configuration flags; the updated interop test scenarios ran successfully.

Codex Task

MisterVVP · 2026-06-30T06:58:28Z

More refactoring to be added before reviewing this

MisterVVP · 2026-06-30T10:42:09Z

@codex review this pr

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MisterVVP · 2026-06-30T12:35:49Z

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MisterVVP · 2026-06-30T21:47:37Z

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### Motivation - Reduce duplicated HTTP method and protocol path literals (e.g. `"GET"`, `"/extendedAgentCard"`) and centralize them as a single source of truth. - Prefer header declarations for protocol/transport constants so clients and server components use the same canonical values and avoid drift. ### Description - Added `a2a::core::protocol_paths` header with `kAgentCard`, `kLegacyAgentCard`, `kExtendedAgentCard`, and `kWellKnownPrefix` constants and used it across discovery and server routing. - Introduced `kMethodDelete` into `a2a::core::http` and replaced scattered literal method strings with `core::http::kMethodGet`, `kMethodPost`, and `kMethodDelete` in clients, transports, and push delivery code. - Updated `RestServerTransport` public path aliases to reference the new core protocol path constants and adjusted `TransportMux`, `RestTransport`, `HttpJsonTransport`, `JsonRpcTransport`, and push-delivery code to use shared constants. - Applied a small test-only API fix by adding `[[nodiscard]]` to test agent-card provider overrides to satisfy static analysis. ### Testing - Ran formatting checks via `./scripts/run_clang_format.sh` and `clang-format --dry-run --Werror` which completed successfully. - Ran the repository validation via `./scripts/verify_changes.sh` which performed configure/build/`ctest` and `clang-tidy` and completed with all checks passing. - All automated tests (unit, functional, and integration) executed under `ctest` and reported `100%` passed. - Attempted the local TCK flow with `./scripts/run_tck_sut.sh && ./scripts/run_tck_mandatory.sh` but the local TCK runner reported no supported mandatory entrypoint in the checked-out tck repo (SUT started/stopped successfully), so the mandatory-suite could not be executed locally. ------ [Codex Task](https://chatgpt.com/codex/cloud/tasks/task_e_6a44d8d923a48333b1d7d0fb00edb563)

MisterVVP · 2026-07-01T15:55:57Z

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MisterVVP · 2026-07-01T19:44:04Z

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MisterVVP · 2026-07-02T07:28:54Z

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chatgpt-codex-connector · 2026-07-02T07:39:40Z

+    return DispatchRequest{.operation = DispatcherOperation::kGetExtendedAgentCard,
+                           .payload = std::move(payload.value())};


Return the extended-card ErrorInfo reason

When this new JSON-RPC method is dispatched without an AgentCardProvider, the dispatcher returns protocol code -32007, but BuildErrorResponse still gets its ErrorInfo reason from ErrorInfoReason, which has no kExtendedAgentCardNotConfigured branch. JSON-RPC clients therefore see protocolCode: -32007 with reason UNSUPPORTED_OPERATION, unlike the REST and gRPC paths added in this change; add the missing mapping so the error metadata is consistent.

Useful? React with 👍 / 👎.

Decouple extended agent card from transports

013572f

MisterVVP added the codex label Jun 29, 2026 — with ChatGPT Codex Connector

MisterVVP linked an issue Jun 29, 2026 that may be closed by this pull request

[Feature]: Extended Agent Card support #109

Open

Fix extended agent card build regressions

7c96d6e

MisterVVP marked this pull request as draft June 29, 2026 21:28

Fix benchmark and extended card routing regressions

f19e398

MisterVVP self-assigned this Jun 29, 2026

MisterVVP and others added 2 commits June 30, 2026 12:06

refactor: add non-copyable helper base classes

db021fd

fix: clang fmt

2308715

chatgpt-codex-connector Bot reviewed Jun 30, 2026

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Comment thread src/server/rest_server_transport.cpp Outdated

Comment thread src/server/dispatcher.cpp Outdated

MisterVVP and others added 6 commits June 30, 2026 14:01

fix: propagate tenant to extended card provider

83393bd

fix: propagate tenant to extended card provider

799cd82

fix: add tenant parameter to REST extended card handler

2a1c2f0

fix: route extended card discovery requests

2e61429

test: cover REST extended card discovery routes

a15590a

fix: clang fmt

6d0489b

chatgpt-codex-connector Bot reviewed Jun 30, 2026

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Comment thread src/server/rest_server_transport.cpp

Comment thread src/server/json_rpc_server_transport.cpp Outdated

Comment thread src/server/rest_server_transport.cpp Outdated

MisterVVP and others added 4 commits June 30, 2026 22:46

fix: use spec extended card discovery endpoint

9f97459

test: cover spec extended card discovery URL

ff93572

address review threads

8029bf5

fix: clang tidy optional access

b4ec4c2

chatgpt-codex-connector Bot reviewed Jun 30, 2026

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Comment thread src/server/transport_mux.cpp Outdated

Comment thread src/server/rest_server_transport.cpp

MisterVVP and others added 3 commits July 1, 2026 10:52

fix: route tenant extended cards through mux

25b8866

fix dispatcher

d752fe8

chatgpt-codex-connector Bot reviewed Jul 1, 2026

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Comment thread src/server/json_rpc_server_transport.cpp

Comment thread include/a2a/core/core.h

MisterVVP and others added 3 commits July 1, 2026 22:07

fix: accept extended agent card JSON-RPC alias

7c1b72f

add compatibility header

f92e3f6

clang fmt

408109d

chatgpt-codex-connector Bot reviewed Jul 1, 2026

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Comment thread src/server/json_rpc_server_transport.cpp

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		return DispatchRequest{.operation = DispatcherOperation::kGetExtendedAgentCard,
		.payload = std::move(payload.value())};

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MisterVVP commented Jun 29, 2026

Motivation

Description

Testing

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