Configure JS220 frontend

Instructions

Implementation Reference

• src/joulescope_mcp/service.py:199-232 (handler)

  Actual implementation of configure_frontend. Validates allowed modes (auto/manual/off), builds driver topic commands for current/voltage range mode and range selection, publishes them via the driver, and returns the list of published topics.

  def configure_frontend(
      self,
      device_path: str | None = None,
      current_range_mode: str | None = "auto",
      voltage_range_mode: str | None = "auto",
      current_range: str | None = None,
      voltage_range: str | None = None,
  ) -> dict[str, Any]:
      allowed_mode = {"auto", "manual", "off"}
      if current_range_mode is not None and current_range_mode not in allowed_mode:
          raise JoulescopeMcpError(f"current_range_mode must be one of {sorted(allowed_mode)}")
      if voltage_range_mode is not None and voltage_range_mode not in allowed_mode:
          raise JoulescopeMcpError(f"voltage_range_mode must be one of {sorted(allowed_mode)}")
  
      published: list[dict[str, Any]] = []
      with self._driver_session() as driver:
          device = self._select_device(driver, device_path=device_path)
          driver.open(device, mode="restore")
          try:
              commands: list[tuple[str, Any]] = []
              if current_range_mode is not None:
                  commands.append((f"{device}/s/i/range/mode", current_range_mode))
              if voltage_range_mode is not None:
                  commands.append((f"{device}/s/v/range/mode", voltage_range_mode))
              if current_range is not None:
                  commands.append((f"{device}/s/i/range/select", current_range))
              if voltage_range is not None:
                  commands.append((f"{device}/s/v/range/select", voltage_range))
              for topic, value in commands:
                  driver.publish(topic, value)
                  published.append({"topic": topic, "value": value})
          finally:
              driver.close(device)
      return {"device_path": device, "published": published}

• src/joulescope_mcp/server.py:115-137 (registration)

  MCP tool registration for configure_frontend using @mcp.tool decorator. Defines the tool schema (title, description, annotations with config_tool, structured_output) and parameter types including Literal constraints. Delegates to service.configure_frontend.

  @mcp.tool(
      title="Configure JS220 frontend",
      description="Configure JS220 current and voltage range modes. Use auto for normal agent measurements.",
      annotations=config_tool,
      structured_output=True,
  )
  def configure_frontend(
      device_path: str | None = None,
      current_range_mode: Literal["auto", "manual", "off"] | None = "auto",
      voltage_range_mode: Literal["auto", "manual", "off"] | None = "auto",
      current_range: str | None = None,
      voltage_range: str | None = None,
  ) -> dict[str, Any]:
      try:
          return service.configure_frontend(
              device_path=device_path,
              current_range_mode=current_range_mode,
              voltage_range_mode=voltage_range_mode,
              current_range=current_range,
              voltage_range=voltage_range,
          )
      except JoulescopeMcpError as exc:
          raise _tool_error(exc) from exc

• src/joulescope_mcp/server.py:34-34 (schema)

  config_tool annotation definition used for configure_frontend: readOnlyHint=False, destructiveHint=False, idempotentHint=True (configuring frontend is idempotent).

  config_tool = ToolAnnotations(readOnlyHint=False, destructiveHint=False, idempotentHint=True)

• tests/test_service.py:177-183 (helper)

  Unit test for configure_frontend verifying that publishing the expected topics ('s/i/range/mode' and 's/v/range/mode') with values 'auto' works correctly.

  def test_configure_frontend_publishes_expected_topics() -> None:
      driver = FakeDriver()
      result = service_with(driver).configure_frontend(current_range_mode="auto", voltage_range_mode="auto")
      assert result["published"] == [
          {"topic": "u/js220/005920/s/i/range/mode", "value": "auto"},
          {"topic": "u/js220/005920/s/v/range/mode", "value": "auto"},
      ]