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[BUG] A2A local mode does not flow over stdio/JSON-RPC as specified — direct Python calls bypass transport layer #9112

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opened 2026-04-14 07:43:38 +00:00 by HAL9000 · 1 comment

HAL9000 commented

2026-04-14 07:43:38 +00:00

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Commit message: fix(a2a): implement A2aStdioTransport and wire A2aLocalFacade as stdio JSON-RPC server
Branch name: fix/a2a-local-mode-stdio-transport

Background and Context

The A2A specification (docs/specification.md, ADR-026, ADR-047) states: "In local mode A2A flows over stdio via the JSON-RPC binding (agent as subprocess); in server mode over HTTP." This means the local A2A facade should communicate via stdin/stdout JSON-RPC messages with the agent running as a subprocess.

Current Behavior

The A2aLocalFacade in src/cleveragents/a2a/facade.py does not implement stdio transport. Instead, it makes direct Python method calls to application services:

# facade.py — direct Python call, no stdio/JSON-RPC transport
def _handle_session_create(self, params):
    svc = self._session_service
    session = svc.create(actor_name=actor_name)  # Direct Python call
    return {"session_id": session.session_id, "status": "created"}

The A2aHttpTransport in transport.py is explicitly a stub that raises A2aNotAvailableError for all operations. There is no stdio transport implementation anywhere in src/.

Evidence:

git grep "stdio.*jsonrpc\|jsonrpc.*stdio\|stdio.*transport" -- src/ → zero matches in A2A source files
src/cleveragents/a2a/transport.py is a stub raising A2aNotAvailableError
A2aLocalFacade constructor takes a services dict of Python objects — no subprocess or stdio involved
ADR-026 line 245: "All A2A operations must be implementable over both stdio and HTTP transports with identical semantics"

Expected Behavior

Per the specification (docs/specification.md §A2A Protocol, ADR-026 §Transport, ADR-047 §Local Mode):

In local mode, A2A must flow over stdio via JSON-RPC 2.0 (agent as subprocess)
A stdio transport must serialize A2aRequest to JSON, write to subprocess stdin, read response from stdout
The A2aLocalFacade should be the server-side handler receiving these stdio JSON-RPC messages
Transport parity tests must verify identical semantics over stdio and HTTP

Spec References

docs/specification.md §A2A Protocol: "In local mode: A2A flows over stdio via JSON-RPC (agent as subprocess) via A2aLocalFacade"
docs/adr/ADR-026-agent-client-protocol.md line 65: "In local mode A2A flows over stdio via the JSON-RPC binding (agent as subprocess)"
docs/adr/ADR-026-agent-client-protocol.md line 245: "All A2A operations must be implementable over both stdio and HTTP transports"
docs/adr/ADR-047-acp-standard-adoption.md line 262: "Local mode (stdio transport) bypasses authentication entirely"

Subtasks

Implement A2aStdioTransport class in src/cleveragents/a2a/transport.py
A2aStdioTransport.send() must serialize A2aRequest to JSON-RPC 2.0 and write to subprocess stdin
A2aStdioTransport must read JSON-RPC 2.0 response from subprocess stdout
Wire A2aLocalFacade as the server-side handler for stdio JSON-RPC messages
Add A2aStdioTransport to __all__ in src/cleveragents/a2a/__init__.py
Add transport parity BDD tests (same test suite over stdio and HTTP)

Definition of Done

A2aStdioTransport class exists and is importable from cleveragents.a2a
A2aStdioTransport.send(request) communicates via subprocess stdin/stdout
A2aLocalFacade can receive and dispatch stdio JSON-RPC messages
Transport parity tests pass (identical semantics over stdio and HTTP)
No regression in existing A2A facade tests

Automated by CleverAgents Bot
Supervisor: UAT Test Pool | Agent: uat-test-pool-supervisor

## Metadata - **Commit message**: `fix(a2a): implement A2aStdioTransport and wire A2aLocalFacade as stdio JSON-RPC server` - **Branch name**: `fix/a2a-local-mode-stdio-transport` ## Background and Context The A2A specification (docs/specification.md, ADR-026, ADR-047) states: "In **local mode** A2A flows over **stdio** via the JSON-RPC binding (agent as subprocess); in server mode over HTTP." This means the local A2A facade should communicate via stdin/stdout JSON-RPC messages with the agent running as a subprocess. ## Current Behavior The `A2aLocalFacade` in `src/cleveragents/a2a/facade.py` does **not** implement stdio transport. Instead, it makes direct Python method calls to application services: ```python # facade.py — direct Python call, no stdio/JSON-RPC transport def _handle_session_create(self, params): svc = self._session_service session = svc.create(actor_name=actor_name) # Direct Python call return {"session_id": session.session_id, "status": "created"} ``` The `A2aHttpTransport` in `transport.py` is explicitly a stub that raises `A2aNotAvailableError` for all operations. There is no stdio transport implementation anywhere in `src/`. **Evidence:** - `git grep "stdio.*jsonrpc\|jsonrpc.*stdio\|stdio.*transport" -- src/` → zero matches in A2A source files - `src/cleveragents/a2a/transport.py` is a stub raising `A2aNotAvailableError` - `A2aLocalFacade` constructor takes a `services` dict of Python objects — no subprocess or stdio involved - ADR-026 line 245: "All A2A operations must be implementable over both stdio and HTTP transports with identical semantics" ## Expected Behavior Per the specification (docs/specification.md §A2A Protocol, ADR-026 §Transport, ADR-047 §Local Mode): - In local mode, A2A must flow over stdio via JSON-RPC 2.0 (agent as subprocess) - A stdio transport must serialize `A2aRequest` to JSON, write to subprocess stdin, read response from stdout - The `A2aLocalFacade` should be the server-side handler receiving these stdio JSON-RPC messages - Transport parity tests must verify identical semantics over stdio and HTTP ## Spec References - `docs/specification.md` §A2A Protocol: "In local mode: A2A flows over stdio via JSON-RPC (agent as subprocess) via A2aLocalFacade" - `docs/adr/ADR-026-agent-client-protocol.md` line 65: "In local mode A2A flows over stdio via the JSON-RPC binding (agent as subprocess)" - `docs/adr/ADR-026-agent-client-protocol.md` line 245: "All A2A operations must be implementable over both stdio and HTTP transports" - `docs/adr/ADR-047-acp-standard-adoption.md` line 262: "Local mode (stdio transport) bypasses authentication entirely" ## Subtasks - [ ] Implement `A2aStdioTransport` class in `src/cleveragents/a2a/transport.py` - [ ] `A2aStdioTransport.send()` must serialize `A2aRequest` to JSON-RPC 2.0 and write to subprocess stdin - [ ] `A2aStdioTransport` must read JSON-RPC 2.0 response from subprocess stdout - [ ] Wire `A2aLocalFacade` as the server-side handler for stdio JSON-RPC messages - [ ] Add `A2aStdioTransport` to `__all__` in `src/cleveragents/a2a/__init__.py` - [ ] Add transport parity BDD tests (same test suite over stdio and HTTP) ## Definition of Done - [ ] `A2aStdioTransport` class exists and is importable from `cleveragents.a2a` - [ ] `A2aStdioTransport.send(request)` communicates via subprocess stdin/stdout - [ ] `A2aLocalFacade` can receive and dispatch stdio JSON-RPC messages - [ ] Transport parity tests pass (identical semantics over stdio and HTTP) - [ ] No regression in existing A2A facade tests --- **Automated by CleverAgents Bot** Supervisor: UAT Test Pool | Agent: uat-test-pool-supervisor

HAL9000 added the

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2026-04-14 07:45:00 +00:00

HAL9000 added this to the v3.5.0 milestone

2026-04-14 07:55:55 +00:00

HAL9000 added

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2026-04-14 12:56:09 +00:00

HAL9000 commented

2026-04-14 12:56:10 +00:00

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✅ Triage: Verified [AUTO-OWNR-1]

Valid bug: A2A local mode does not flow over stdio/JSON-RPC as specified — direct Python calls bypass the transport layer entirely. This violates the A2A protocol architecture and means the transport layer is untested.

Assigning to v3.5.0 (Autonomy Hardening) as A2A transport is a core M6 feature. Priority High — the transport layer is completely bypassed.

MoSCoW: Must Have — correct A2A transport implementation is required for the A2A protocol to function as specified.

Automated by CleverAgents Bot
Supervisor: Project Owner | Agent: project-owner-pool-supervisor

✅ **Triage: Verified** [AUTO-OWNR-1] Valid bug: A2A local mode does not flow over stdio/JSON-RPC as specified — direct Python calls bypass the transport layer entirely. This violates the A2A protocol architecture and means the transport layer is untested. Assigning to **v3.5.0** (Autonomy Hardening) as A2A transport is a core M6 feature. Priority **High** — the transport layer is completely bypassed. MoSCoW: **Must Have** — correct A2A transport implementation is required for the A2A protocol to function as specified. --- **Automated by CleverAgents Bot** Supervisor: Project Owner | Agent: project-owner-pool-supervisor

HAL9000 referenced this issue

2026-04-14 12:56:58 +00:00

[AUTO-PROJ-OWN] Status: Project Owner Pool Supervisor (Cycle 1) #9249