enbility / eebus-go

95%

Build Type

push

github

Committed by web-flow

Commit Message

Fix wrong parameter description selection in LoadControlLimits (#218)

Fixes #217.

Asked Claude for a fix since
[evcc-io/evcc](https://github.com/evcc-io/evcc) uses both opev and
oscev. Fix is LGTM.

## Problem

`LoadControlLimits` and `WriteLoadControlPhaseLimits` in
`usecases/internal/loadcontrol.go` looked up
`ElectricalConnectionParameterDescription` entries filtered only by
`AcMeasuredPhases` and then blindly used `elParamDesc[0]`. If a remote
device exposes more than one description per phase (e.g. current and
voltage), the wrong entry could be picked and the limit would be
resolved against an unrelated `MeasurementId` / `ParameterId`.
Additionally, `*elParamDesc[0].ParameterId` was dereferenced without a
nil guard on the write side, which could panic against a conformant
remote that omits the optional `ParameterId`.

Not observed on Elli, Porsche MCC, or SMA HEM 2.0 (they only expose
current descriptions), but a conformant device is allowed to expose more
— and the bug surfaces whenever a non-current description is listed
first.

## Fix

Walk all parameter descriptions for the phase and pick the one whose
`MeasurementId` is referenced by one of the limit descriptions, then use
that description's `ParameterId` for the permitted-value lookup /
adjustment. Adds the missing `ParameterId` nil guard on the write path.

The four public entry points are all thin wrappers over the two internal
helpers and inherit the fix:

- `opev.OPEV.LoadControlLimits` / `opev.OPEV.WriteLoadControlLimits`
- `oscev.OSCEV.LoadControlLimits` / `oscev.OSCEV.WriteLoadControlLimits`

Coverage Stats

28 of 30 new or added lines in 1 file covered. (93.33%)

1 existing line in 1 file now uncovered.

7248 of 7608 relevant lines covered (95.27%)

12.41 hits per line