MST100: expose water flow status (wflow) and possible water consumption data

[drstewa60-lgtm]

Hi,

I have been testing a Meross MST100 sprinkler timer connected to an MSH400 hub with meross_lan 5.8.0.

I found that the MST100 reports a useful wflow value in the hub's Appliance.System.All digest, which is currently not exposed as an entity by meross_lan.

Example:

"mst": {
  "dura": 18,
  "wflow": 1
}
I performed controlled tests with normal water flow and with the downstream water line mechanically closed.
The results were reproducible:
wflow = 1 → normal water flow detected
wflow = 2 → no/insufficient water flow detected
The wflow = 2 condition also corresponds to the flow warning shown by the official Meross app.
One important observation: the final wflow result seems to become available only a few seconds after watering has stopped. Manually refreshing Appliance.System.All after the watering cycle reliably returns the updated value.
I locally modified MST100SubDevice in devices/hub/__init__.py to parse the mst digest and expose wflow as an MLDiagnosticSensor. This works successfully in Home Assistant.
For example:
def _parse_mst(self, p_mst: dict):
    if "wflow" in p_mst:
        self.sensor_water_flow.update_native_value(p_mst["wflow"])
It would be very useful if wflow could be officially exposed by meross_lan.
Water consumption
I also noticed that the MST100 configuration definitions in meross_lan contain:
class DeviceCfg_mstCfg_calibration(TypedDict, total=False):
    waCon: int  # water consumption
    onoff: int
    lmTime: int
However, my MST100 currently reports:
"mstCfg": {
  "dura": 1800,
  "wfm": 1,
  "calibration": {
    "lmTime": 0
  }
}
waCon has not appeared in the diagnostics so far.
The official Meross app provides water-consumption information and also offers an optional flow calibration procedure. Calibration appears to be intended to correct the default measurement rather than being required to enable measurement.
I have also looked at the available WaterEvent/WaterPlan/Digest.WaterPlan data, but so far I have not found the actual water volume/consumption value.
Do you know whether MST100 water consumption is available through a local namespace or through the Meross cloud API?
Also, is waCon actually measured water consumption, or is it a calibration parameter?
I can provide diagnostics showing both wflow = 1 and wflow = 2, as well as my modified MST100 code if useful.
Thank you!