Add ambient temperature gate to heating period detection

Adds heating_min_ambient_c (default 15°C) to season config. When outdoor
temperature is at or above this threshold, SG-Ready is suppressed even if
the calendar month is within the heating season. Prevents unnecessary heat
pump boost activation on warm spring/autumn days.

Logic: heating active = in_heating_month AND ambient < threshold
Zero value (unset) disables the temperature gate (calendar-only, old behaviour).

New test: TestHeatingPeriodAmbientSuppression covers warm-day suppression,
cold-day pass-through, and summer month independence.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

configs/ems-config.yaml

@@ -86,6 +86,7 @@ consumers:
 season:
   heating_start_month: 10   # October
   heating_end_month: 4      # April
+  heating_min_ambient_c: 15 # above 15°C outdoor temp: no SG-Ready even within heating months
 
 # PV forecast — forecast.solar (free, no API key required)
 forecast:

internal/config/config.go

@@ -120,10 +120,11 @@ type StrategicConfig struct {
 	ScheduleOff     string  `yaml:"schedule_off"`
 }
 
-// SeasonConfig defines the heating season by month range.
+// SeasonConfig defines the heating season by month range and ambient temperature.
 type SeasonConfig struct {
-	HeatingStartMonth int `yaml:"heating_start_month"`
-	HeatingEndMonth   int `yaml:"heating_end_month"`
+	HeatingStartMonth  int     `yaml:"heating_start_month"`
+	HeatingEndMonth    int     `yaml:"heating_end_month"`
+	HeatingMinAmbientC float64 `yaml:"heating_min_ambient_c"` // above this: non-heating regardless of month (0 = disabled)
 }
 
 // ForecastConfig holds forecast.solar API parameters.

internal/engine/engine.go

@@ -107,7 +107,7 @@ func (e *Engine) Decide(state collector.SystemState, now time.Time, wwBoostC flo
 
 	soc := state.BatterySOC
 	gridW := state.GridPowerW // positive = import, negative = export
-	heatingPeriod := e.isHeatingPeriod(now)
+	heatingPeriod := e.isHeatingPeriod(now, state.AmbientTempC)
 	wwWindow := e.isWWWindow(now)
 	allowed := e.allowedConsumers(soc)
 
@@ -502,17 +502,37 @@ func (e *Engine) ApplyOverride(consumer Consumer, on bool, duration time.Duratio
 	)
 }
 
-// isHeatingPeriod returns true if the current month is within the heating season.
-func (e *Engine) isHeatingPeriod(now time.Time) bool {
+// isHeatingPeriod returns true if heating is appropriate given the current month
+// and outdoor temperature. If HeatingMinAmbientC is configured (> 0), ambient
+// temperatures above that threshold suppress SG-Ready even within the heating months.
+func (e *Engine) isHeatingPeriod(now time.Time, ambientC float64) bool {
 	month := int(now.Month())
 	start := e.cfg.Season.HeatingStartMonth
 	end := e.cfg.Season.HeatingEndMonth
 
 	// Handles wrap-around: e.g. October(10) to April(4)
+	var inMonth bool
 	if start > end {
-		return month >= start || month <= end
+		inMonth = month >= start || month <= end
+	} else {
+		inMonth = month >= start && month <= end
 	}
-	return month >= start && month <= end
+
+	if !inMonth {
+		return false
+	}
+
+	// Temperature override: warm day within heating months → not a heating day
+	threshold := e.cfg.Season.HeatingMinAmbientC
+	if threshold > 0 && ambientC >= threshold {
+		e.logger.Debug("heating period suppressed by ambient temperature",
+			"ambient_c", ambientC,
+			"threshold_c", threshold,
+		)
+		return false
+	}
+
+	return true
 }
 
 // minRuntime returns the minimum runtime for a consumer.

internal/engine/engine_test.go

@@ -208,6 +208,7 @@ func TestShutdownReverseOrder(t *testing.T) {
 
 func TestHeatingPeriodDetection(t *testing.T) {
 	eng := NewEngine(testConfig(), testLogger())
+	cold := 5.0 // well below any threshold — pure calendar test
 
 	tests := []struct {
 		month    time.Month
@@ -230,13 +231,36 @@ func TestHeatingPeriodDetection(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.month.String(), func(t *testing.T) {
 			date := time.Date(2025, tt.month, 15, 12, 0, 0, 0, time.UTC)
-			if got := eng.isHeatingPeriod(date); got != tt.expected {
+			if got := eng.isHeatingPeriod(date, cold); got != tt.expected {
 				t.Errorf("month %s: got %v, want %v", tt.month, got, tt.expected)
 			}
 		})
 	}
 }
 
+func TestHeatingPeriodAmbientSuppression(t *testing.T) {
+	cfg := testConfig()
+	cfg.Season.HeatingMinAmbientC = 15.0
+	eng := NewEngine(cfg, testLogger())
+
+	// Winter month, but warm day — should be suppressed
+	warmWinterDay := time.Date(2025, time.January, 15, 12, 0, 0, 0, time.UTC)
+	if eng.isHeatingPeriod(warmWinterDay, 18.0) {
+		t.Error("expected heating period suppressed when ambient (18°C) >= threshold (15°C)")
+	}
+
+	// Winter month, cold day — should be active
+	if !eng.isHeatingPeriod(warmWinterDay, 8.0) {
+		t.Error("expected heating period active when ambient (8°C) < threshold (15°C)")
+	}
+
+	// Summer month, cold day — still not heating (month gate takes precedence)
+	summerDay := time.Date(2025, time.July, 15, 12, 0, 0, 0, time.UTC)
+	if eng.isHeatingPeriod(summerDay, 5.0) {
+		t.Error("expected heating period inactive in summer regardless of temperature")
+	}
+}
+
 func TestWallboxMutualExclusion(t *testing.T) {
 	cfg := testConfig()
 	cfg.Hysteresis.ExportOnDuration = "0s"