Tinkerforge WARP: detect EV features via info/features

Requires WARP4 firmware announcing the ev feature, see
Tinkerforge/esp32-firmware#503.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: poohnet

charger/warp-ws.go

@@ -102,9 +102,8 @@ func NewWarpWSFromConfig(ctx context.Context, other map[string]any) (api.Charger
 		implement.Has(w, implement.PhaseVoltages(w.voltages))
 	}
 
-	// Feature: EV (WARP4): vehicle soc and mac read via ISO 15118;
-	// not announced in info/features, hence probing the api
-	hasEv := w.hasEvState()
+	// Feature: EV (WARP4): vehicle soc and mac read via ISO 15118
+	hasEv := w.hasFeature(warp.FeatureEv)
 	if hasEv {
 		implement.Has(w, implement.Battery(w.soc))
 	}
@@ -455,12 +454,6 @@ func (w *WarpWS) identify() (string, error) {
 	return w.chargeTracker.AuthorizationInfo.TagId, nil
 }
 
-// hasEvState probes the ev/state api provided by WARP4 devices
-func (w *WarpWS) hasEvState() bool {
-	var res warp.EvState
-	return w.GetJSON(fmt.Sprintf("%s/ev/state", w.URI), &res) == nil
-}
-
 // soc implements the api.Battery interface
 func (w *WarpWS) soc() (float64, error) {
 	w.mu.RLock()

charger/warp/types.go

@@ -1,6 +1,7 @@
 package warp
 
 const (
+	FeatureEv             = "ev"
 	FeatureMeter          = "meter"
 	FeatureMeters         = "meters"
 	FeatureMeterAllValues = "meter_all_values"