feat(sensors): add trend_change_in_minutes countdown sensor

New duration sensor showing time until next price trend change as hours
(e.g., 2.25 h). Registered in MINUTE_UPDATE_ENTITY_KEYS for per-minute
updates. Shares cached attributes with next_price_trend_change timestamp
sensor.

Added trend attributes to _unrecorded_attributes (threshold/volatility/diff
attributes excluded from recorder). Updated timer group size test expectation
from 6 to 7.

Impact: Users can display a live countdown to the next trend change on
dashboards and use it in automations (e.g., "if < 0.25 h, prepare").

custom_components/tibber_prices/coordinator/constants.py

@@ -108,5 +108,7 @@ MINUTE_UPDATE_ENTITY_KEYS = frozenset(
         "peak_price_remaining_minutes",
         "peak_price_progress",
         "peak_price_next_in_minutes",
+        # Trend change countdown sensor (needs minute updates)
+        "trend_change_in_minutes",
     }
 )

custom_components/tibber_prices/sensor/attributes/trend.py

@@ -37,3 +37,6 @@ def _add_cached_trend_attributes(attributes: dict, key: str, cached_data: dict)
         # Add cached attributes (timestamp already set by platform)
         # State contains the timestamp of the trend change itself
         attributes.update(cached_data["trend_change_attributes"])
+    elif key == "trend_change_in_minutes" and cached_data.get("trend_change_attributes"):
+        # Duration sensor shares same cached attributes as the timestamp sensor
+        attributes.update(cached_data["trend_change_attributes"])

custom_components/tibber_prices/sensor/core.py

@@ -120,6 +120,22 @@ class TibberPricesSensor(TibberPricesEntity, RestoreSensor):
             "cache_validity",
             "data_completeness",
             "data_status",
+            "threshold_rising_%",
+            "threshold_rising_strongly_%",
+            "threshold_falling_%",
+            "threshold_falling_strongly_%",
+            "volatility_factor",
+            "interval_count",
+            "price_direction_since",
+            "price_now",
+            "trend_diff_%",
+            # Dynamic keys for second_half diff (all trend hour variants)
+            "second_half_3h_diff_from_current_%",
+            "second_half_4h_diff_from_current_%",
+            "second_half_5h_diff_from_current_%",
+            "second_half_6h_diff_from_current_%",
+            "second_half_8h_diff_from_current_%",
+            "second_half_12h_diff_from_current_%",
             # Static/Rarely Changing
             "tomorrow_expected_after",
             "level_value",
@@ -313,7 +329,11 @@ class TibberPricesSensor(TibberPricesEntity, RestoreSensor):
         if self.entity_description.key.startswith("price_trend_"):
             self._trend_calculator.clear_trend_cache()
         # Clear trend calculation cache for trend sensors
-        elif self.entity_description.key in ("current_price_trend", "next_price_trend_change"):
+        elif self.entity_description.key in (
+            "current_price_trend",
+            "next_price_trend_change",
+            "trend_change_in_minutes",
+        ):
             self._trend_calculator.clear_calculation_cache()
 
         # For lifecycle sensor: Only write state if it actually changed (state-change filter)

custom_components/tibber_prices/sensor/definitions.py

@@ -517,6 +517,17 @@ FUTURE_TREND_SENSORS = (
         state_class=None,  # Timestamp: no statistics
         entity_registry_enabled_default=True,
     ),
+    # Trend change countdown sensor (how long until trend changes?)
+    SensorEntityDescription(
+        key="trend_change_in_minutes",
+        translation_key="trend_change_in_minutes",
+        icon="mdi:timer-outline",
+        device_class=SensorDeviceClass.DURATION,
+        native_unit_of_measurement=UnitOfTime.HOURS,
+        state_class=None,  # Countdown timer: no statistics
+        suggested_display_precision=2,
+        entity_registry_enabled_default=True,
+    ),
     # Price trend forecast sensors (will prices be higher/lower in X hours?)
     # Default enabled: 1h-5h
     SensorEntityDescription(

custom_components/tibber_prices/sensor/value_getters.py

@@ -205,6 +205,7 @@ def get_value_getter_mapping(  # noqa: PLR0913 - needs all calculators as parame
         # Current and next trend change sensors
         "current_price_trend": trend_calculator.get_current_trend_value,
         "next_price_trend_change": trend_calculator.get_next_trend_change_value,
+        "trend_change_in_minutes": lambda: _minutes_to_hours(trend_calculator.get_trend_change_in_minutes_value()),
         # Price trend sensors
         "price_trend_1h": lambda: trend_calculator.get_price_trend_value(hours=1),
         "price_trend_2h": lambda: trend_calculator.get_price_trend_value(hours=2),

tests/test_sensor_timer_assignment.py

@@ -448,7 +448,7 @@ def test_timer_group_sizes() -> None:
     """
     # As of Nov 2025
     expected_time_sensitive_min = 40  # At least 40 sensors
-    expected_minute_update = 6  # Exactly 6 timing sensors
+    expected_minute_update = 7  # Exactly 7 timing sensors
 
     assert len(TIME_SENSITIVE_ENTITY_KEYS) >= expected_time_sensitive_min, (
         f"Expected at least {expected_time_sensitive_min} TIME_SENSITIVE sensors, got {len(TIME_SENSITIVE_ENTITY_KEYS)}"