Summary

When a Matter controller sends a SetActivePresetRequest command to a thermostat, the ActivePresetHandle attribute is correctly updated on the device side (confirmed via a subsequent read), but no subscription report is sent to notify subscribers of the change. This means controllers relying on subscriptions (such as python-matter-server / Home Assistant) never learn about the new value unless they explicitly poll the attribute.

Root cause

In thermostat-server-presets.cpp, SetActivePreset() calls delegate->SetActivePresetHandle() but does not call MatterReportingAttributeChangeCallback afterwards to mark the attribute as dirty:

Status ThermostatAttrAccess::SetActivePreset(EndpointId endpoint, DataModel::Nullable<ByteSpan> presetHandle)
{
    // ...
    CHIP_ERROR err = delegate->SetActivePresetHandle(presetHandle);

    if (err != CHIP_NO_ERROR)
    {
        ChipLogError(Zcl, "Failed to set ActivePresetHandle with error %" CHIP_ERROR_FORMAT, err.Format());
        return StatusIB(err).mStatus;
    }

    return Status::Success;
    // ← MatterReportingAttributeChangeCallback(..., ActivePresetHandle::Id) is missing here
}

Expected behavior

After a successful SetActivePresetHandle, the framework should be notified that ActivePresetHandle has changed, so that all active subscriptions receive a Report Data message with the new value.

Proposed fix

Add a call to MatterReportingAttributeChangeCallback after the delegate call succeeds:

    CHIP_ERROR err = delegate->SetActivePresetHandle(presetHandle);

    if (err != CHIP_NO_ERROR)
    {
        ChipLogError(Zcl, "Failed to set ActivePresetHandle with error %" CHIP_ERROR_FORMAT, err.Format());
        return StatusIB(err).mStatus;
    }

    MatterReportingAttributeChangeCallback(endpoint, Thermostat::Id, ActivePresetHandle::Id);

    return Status::Success;

1. Commission a thermostat supporting the Presets feature (e.g. Eve Thermo, or the Linux thermostat example)
2. Subscribe to ActivePresetHandle (attribute 0x004E, cluster 0x0201)
3. Send SetActivePresetRequest with a valid preset handle
4. Observe: no subscription report is received, even after several minutes
5. Send a read active-preset-handle → the new value is returned correctly

Impact

Any Matter controller using subscriptions (the standard approach) will never receive the updated ActivePresetHandle value after a SetActivePresetRequest. Workarounds such as optimistic local state updates are required on the controller side to maintain a consistent UI.

Confirmed against: Linux thermostat example (examples/thermostat/linux) and Eve Thermo hardware.

Bug prevalence

always

GitHub hash of the SDK that was being used

fa956ce

Platform

linux

Platform Version(s)

No response

Anything else?

No response