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ant_ai.acp.adapter

ACPAdapter

Bases: Agent

Adapts an ant-ai Agent + Workflow to the ACP Agent stdio protocol.

Explicitly implements :class:acp.interfaces.Agent so type checkers verify the full protocol surface is covered.

Can be used directly with :func:acp.run_agent for stdio mode, or wrapped in an :class:ACPServer for WebSocket/ASGI mode.

Source code in src/ant_ai/acp/adapter.py
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class ACPAdapter(ACPAgent):
    """Adapts an ant-ai Agent + Workflow to the ACP Agent stdio protocol.

    Explicitly implements :class:`acp.interfaces.Agent` so type checkers
    verify the full protocol surface is covered.

    Can be used directly with :func:`acp.run_agent` for stdio mode, or
    wrapped in an :class:`ACPServer` for WebSocket/ASGI mode.
    """

    def __init__(
        self,
        agent: Agent,
        workflow: Workflow,
        *,
        commands: list[ACPCommand] | None = None,
        context_class: type[InvocationContext] = InvocationContext,
    ) -> None:
        self._agent: Agent = agent
        self._workflow: Workflow[State] = workflow
        self._context_class: type[InvocationContext] = context_class
        self._commands: dict[str, ACPCommand] = {c.name: c for c in (commands or [])}
        self._available_commands: list[AvailableCommand] = [
            c.to_available_command() for c in (commands or [])
        ]
        self._client: Client | None = None
        self._client_capabilities: ClientCapabilities | None = None
        self._sessions: dict[str, list[Message]] = {}
        self._session_agents: dict[str, Agent] = {}
        self._session_cwds: dict[str, str] = {}
        self._session_commands_sent: set[str] = set()
        self._translator = HVEventToACP()

    def on_connect(self, conn: Client) -> None:
        self._client: Client = conn

    def _set_session_agent(self, session_id: str, agent: Agent) -> None:
        self._session_agents[session_id] = agent

    async def initialize(
        self,
        protocol_version: int,
        client_capabilities: ClientCapabilities | None = None,
        client_info: Implementation | None = None,
        **kwargs: Any,
    ) -> InitializeResponse:
        self._client_capabilities: ClientCapabilities | None = client_capabilities
        return InitializeResponse(
            protocol_version=protocol_version,
            agent_info=Implementation(name=self._agent.name, version="1.0.0"),
            agent_capabilities=AgentCapabilities(
                load_session=True,
                mcp_capabilities=McpCapabilities(http=True, sse=True),
            ),
        )

    async def new_session(
        self,
        cwd: str,
        additional_directories: list[str] | None = None,
        mcp_servers: _McpServers = None,
        **kwargs: Any,
    ) -> NewSessionResponse:
        session_id = str(uuid.uuid4())
        self._sessions[session_id] = []
        self._session_cwds[session_id] = cwd
        logger.debug("acp: new_session cwd='{}'", cwd)

        session_agent: Agent = self._agent
        if mcp_servers:
            extra_tools: list[Tool] = []
            for srv in mcp_servers:
                if isinstance(srv, HttpMcpServer):
                    extra_tools.extend(await mcp_tools_from_url(srv.url))
                elif isinstance(srv, SseMcpServer):
                    headers: dict[str, str] = {
                        h.name: h.value for h in (srv.headers or [])
                    }
                    extra_tools.extend(
                        await mcp_tools_from_url(
                            srv.url, headers=headers, transport="sse"
                        )
                    )
                # McpServerStdio: subprocess management out of scope
            if extra_tools:
                session_agent: Agent = self._agent.model_copy(
                    update={"tools": [*self._agent.tools, *extra_tools]}
                )
        self._session_agents[session_id] = session_agent

        return NewSessionResponse(session_id=session_id)

    async def load_session(
        self,
        cwd: str,
        session_id: str,
        mcp_servers: _McpServers = None,
        additional_directories: list[str] | None = None,
        **kwargs: Any,
    ) -> LoadSessionResponse | None:
        if session_id not in self._sessions:
            return None
        return LoadSessionResponse()

    async def list_sessions(
        self,
        cwd: str | None = None,
        cursor: str | None = None,
        **kwargs: Any,
    ) -> ListSessionsResponse:
        sessions: list[SessionInfo] = [
            SessionInfo(session_id=sid, cwd="") for sid in self._sessions
        ]
        return ListSessionsResponse(sessions=sessions)

    async def prompt(
        self,
        session_id: str,
        prompt: list[Any],
        message_id: str | None = None,
        **kwargs: Any,
    ) -> PromptResponse:
        _acp_client.set(self._client)
        _acp_session_id.set(session_id)
        _acp_capabilities.set(self._client_capabilities)
        cwd: str | None = self._session_cwds.get(session_id)
        _acp_cwd.set(cwd)
        caps: ClientCapabilities | None = self._client_capabilities
        logger.debug(
            "acp: prompt session={} cwd='{}' fs_read={} fs_write={} terminal={}",
            session_id[:8],
            cwd,
            bool(caps and caps.fs and caps.fs.read_text_file),
            bool(caps and caps.fs and caps.fs.write_text_file),
            bool(caps and caps.terminal),
        )

        text: str = _extract_prompt_text(prompt)

        if (
            self._available_commands
            and self._client
            and session_id not in self._session_commands_sent
        ):
            await self._client.session_update(
                session_id=session_id,
                update=AvailableCommandsUpdate(
                    session_update="available_commands_update",
                    available_commands=self._available_commands,
                ),
            )
            self._session_commands_sent.add(session_id)

        name, args = parse_slash_command(text)
        command = self._commands.get(name) if name else None
        if command is not None and command.kind == "code":
            return await self._run_code_command(command, args, session_id)
        if command is not None and command.kind == "prompt":
            text = command.expand(args)

        history: list[Message] = list(self._sessions.get(session_id, []))
        history.append(Message(role="user", content=text))

        ctx: InvocationContext = self._context_class.from_metadata(
            session_id=session_id
        )
        agent: Agent = self._session_agents.get(session_id, self._agent)
        state: State = self._workflow.create_state(messages=history)

        final_content = ""
        async for event in self._workflow.stream(agent=agent, ctx=ctx, state=state):
            if self._client:
                await self._translator.apply(event, self._client, session_id)
            if isinstance(event, FinalAnswerEvent):
                final_content = event.content

        if session_id in self._sessions:
            self._sessions[session_id].append(Message(role="user", content=text))
            if final_content:
                self._sessions[session_id].append(
                    Message(role="assistant", content=final_content)
                )

        return PromptResponse(stop_reason="end_turn")

    async def _run_code_command(
        self, command: ACPCommand, args: str, session_id: str
    ) -> PromptResponse:
        """Dispatch a ``kind="code"`` command -- no model turn."""
        assert command.handler is not None  # guaranteed by ACPCommand.__post_init__
        ctx = ACPCommandContext(
            args=args,
            session_id=session_id,
            client=self._client,
            capabilities=self._client_capabilities,
            cwd=self._session_cwds.get(session_id),
            history=self._sessions.setdefault(session_id, []),
            agent=self._session_agents.get(session_id, self._agent),
            replace_agent=lambda a: self._set_session_agent(session_id, a),
        )
        try:
            reply = await command.handler(ctx)
        except Exception:
            # Detail stays in the server log; the client gets a generic message so
            # handler internals (paths, config) are not disclosed over the wire.
            logger.exception("acp: /{} failed", command.name)
            reply = f"/{command.name} failed - see server logs."

        if reply and self._client:
            await self._client.session_update(
                session_id=session_id,
                update=AgentMessageChunk(
                    session_update="agent_message_chunk",
                    content=TextContentBlock(type="text", text=reply),
                ),
            )
        return PromptResponse(stop_reason="end_turn")

    async def fork_session(
        self,
        session_id: str,
        cwd: str,
        additional_directories: list[str] | None = None,
        mcp_servers: _McpServers = None,
        **kwargs: Any,
    ) -> ForkSessionResponse:
        new_id = str(uuid.uuid4())
        self._sessions[new_id] = list(self._sessions.get(session_id, []))
        self._session_agents[new_id] = self._session_agents.get(session_id, self._agent)
        return ForkSessionResponse(session_id=new_id)

    async def resume_session(
        self,
        session_id: str,
        cwd: str,
        additional_directories: list[str] | None = None,
        mcp_servers: _McpServers = None,
        **kwargs: Any,
    ) -> ResumeSessionResponse:
        return ResumeSessionResponse()

    async def close_session(
        self, session_id: str, **kwargs: Any
    ) -> CloseSessionResponse | None:
        self._sessions.pop(session_id, None)
        self._session_agents.pop(session_id, None)
        self._session_cwds.pop(session_id, None)
        self._session_commands_sent.discard(session_id)
        return None

    async def authenticate(
        self, method_id: str, **kwargs: Any
    ) -> AuthenticateResponse | None:
        return None

    async def set_session_mode(
        self, session_id: str, mode_id: str, **kwargs: Any
    ) -> SetSessionModeResponse | None:
        return None

    async def set_config_option(
        self, config_id: str, session_id: str, value: str | bool, **kwargs: Any
    ) -> SetSessionConfigOptionResponse | None:
        return None

    async def cancel(self, session_id: str, **kwargs: Any) -> None:
        pass

    async def ext_method(self, method: str, params: dict[str, Any]) -> dict[str, Any]:
        return {}

    async def ext_notification(self, method: str, params: dict[str, Any]) -> None:
        pass