feat(services): isolate price-fetch failures and add success flag to responses

Add a track_degraded parameter to IntervalPool.get_intervals so service calls
(track_degraded=False) never flip the coordinator's sensor-health flags or use
the covers-current-interval cache fallback; authentication errors still
propagate. All price-fetching services now go through
async_fetch_service_intervals and return a structured response with a
top-level success flag: success=false with reason="price_data_unavailable" on
a real API outage, and success=true (possibly empty) otherwise.

Impact: Action calls (get_price, find_cheapest_*, plan_charging) always return
the expected shape, never impair sensors during a Tibber outage, and let
automations distinguish an outage from "no data yet".

custom_components/tibber_prices/interval_pool/manager.py

@@ -10,7 +10,7 @@ from typing import TYPE_CHECKING, Any
 from zoneinfo import ZoneInfo
 
 from custom_components.tibber_prices.api.exceptions import (
-    TibberPricesApiClientCommunicationError,
+    TibberPricesApiClientAuthenticationError,
     TibberPricesApiClientError,
 )
 from homeassistant.util import dt as dt_util
@@ -118,6 +118,13 @@ class TibberPricesIntervalPool:
         self._save_debounce_task: asyncio.Task | None = None
         self._save_lock = asyncio.Lock()
 
+        # Degraded-mode tracking (cache fallback during API outage).
+        # When a fetch fails but cached data still covers the current interval,
+        # the pool keeps serving cached data and flags itself as degraded so the
+        # coordinator can expose this on the connection sensor. Reset on success.
+        self._last_fetch_degraded = False
+        self._last_fetch_error: str | None = None
+
         # DST fall-back extra intervals.
         # On DST fall-back nights (e.g. last Sunday October in EU), wall-clock
         # 02:00-02:45 occurs twice: once in CEST (+02:00) and once in CET (+01:00).
@@ -127,12 +134,24 @@ class TibberPricesIntervalPool:
         # Structure: {"2026-10-25T02:00:00": [{"startsAt": "...+01:00", ...}], ...}
         self._dst_extras: dict[str, list[dict[str, Any]]] = {}
 
+    @property
+    def last_fetch_degraded(self) -> bool:
+        """Return True if the most recent API fetch fell back to cached data."""
+        return self._last_fetch_degraded
+
+    @property
+    def last_fetch_error(self) -> str | None:
+        """Return the error message of the most recent degraded fetch, if any."""
+        return self._last_fetch_error
+
     async def get_intervals(
         self,
         api_client: TibberPricesApiClient,
         user_data: dict[str, Any],
         start_time: datetime,
         end_time: datetime,
+        *,
+        track_degraded: bool = True,
     ) -> tuple[list[dict[str, Any]], bool]:
         """
         Get price intervals for time range (cached + fetch missing).
@@ -152,6 +171,14 @@ class TibberPricesIntervalPool:
             user_data: User data dict containing home metadata.
             start_time: Start of range (inclusive, timezone-aware).
             end_time: End of range (exclusive, timezone-aware).
+            track_degraded: When True (default), API failures update the pool's
+                degraded-state flags (last_fetch_degraded/last_fetch_error) which
+                govern sensor availability, and the cache-fallback path is used to
+                keep sensors alive. This is the SENSOR path (get_sensor_data).
+                When False, the call is a SERVICE request: it must never touch
+                sensor-health state. Any API error is propagated unchanged so the
+                service handler can return a structured "data unavailable" response
+                without impairing sensors.
 
         Returns:
             Tuple of (intervals, api_called):
@@ -203,6 +230,7 @@ class TibberPricesIntervalPool:
 
         # Fetch missing ranges from API
         api_fetch_failed = False
+        fallback_intervals: list[dict[str, Any]] | None = None
         if missing_ranges:
             fetch_time_iso = dt_util.now().isoformat()
 
@@ -214,25 +242,71 @@ class TibberPricesIntervalPool:
                     missing_ranges=missing_ranges,
                     on_intervals_fetched=lambda intervals, _: self._add_intervals(intervals, fetch_time_iso),
                 )
-            except TibberPricesApiClientCommunicationError as err:
+            except TibberPricesApiClientAuthenticationError:
-                if cached_intervals:
+                # Authentication errors must always propagate so the coordinator can
-                    # Transient API error (e.g. 503) but we have cached data - use it as
+                # trigger the reauth flow. Cached data is never a valid fallback here -
-                    # fallback so the coordinator can finish initializing. The next regular
+                # the user must provide a new token.
-                    # update cycle will retry the API automatically.
+                raise
+            except TibberPricesApiClientError as err:
+                # Any other API error (transient communication failure like 503/timeout,
+                # rate limiting, or an "empty data" response during a Tibber outage).
+                if not track_degraded:
+                    # Service request: never mutate sensor-health degraded state and never
+                    # silently serve a partial cache. Propagate so the service handler can
+                    # return a structured "data unavailable" response. Sensor availability
+                    # is governed solely by the regular coordinator update (get_sensor_data).
+                    raise
+                #
+                # Resilience strategy: As long as the cache still covers the CURRENT
+                # interval, keep serving locally cached data so the integration keeps
+                # working benevolently through temporary outages. The next regular update
+                # cycle will retry the API automatically.
+                #
+                # Re-read the cache because the fetcher may have partially cached some
+                # ranges before failing.
+                available_intervals = self._get_cached_intervals(start_time_iso, end_time_iso)
+                if self._covers_current_interval(available_intervals):
                     _LOGGER.warning(
-                        "API temporarily unavailable for home %s (%s) - using %d cached intervals as fallback",
+                        "Tibber API temporarily unavailable for home %s (%s) - continuing with "
+                        "%d cached intervals that still cover the current interval. "
+                        "Will retry on next update cycle",
                         self._home_id,
                         err,
-                        len(cached_intervals),
+                        len(available_intervals),
                     )
                     api_fetch_failed = True
+                    fallback_intervals = available_intervals
+                    # Flag degraded mode so the coordinator/connection sensor can surface it.
+                    self._last_fetch_degraded = True
+                    self._last_fetch_error = str(err)
                 else:
-                    # No cached data at all - re-raise so the caller can decide
+                    # No cached data for the current interval - we cannot serve valid
+                    # prices. Re-raise so the caller can mark the entry as not-ready
+                    # (fresh setup) or raise UpdateFailed (running integration).
+                    _LOGGER.error(
+                        "Tibber API unavailable for home %s (%s) and no cached data covers the "
+                        "current interval - cannot provide price data",
+                        self._home_id,
+                        err,
+                    )
                     raise
+            else:
+                # Fetch succeeded - clear any previous degraded state (sensor path only).
+                # Service requests (track_degraded=False) must not clear a real sensor
+                # degradation, otherwise a successful service fetch could mask it.
+                if track_degraded:
+                    self._last_fetch_degraded = False
+                    self._last_fetch_error = None
 
-        # After caching all API responses, read from cache again to get final result
+        # After caching all API responses, read from cache again to get final result.
-        # This ensures we return exactly what user requested, filtering out extra intervals
+        # This ensures we return exactly what user requested, filtering out extra intervals.
-        final_result = self._get_cached_intervals(start_time_iso, end_time_iso)
+        # When we fell back to cache during an outage, reuse the already-read intervals
+        # instead of querying the cache a second time.
+        final_result = (
+            fallback_intervals
+            if fallback_intervals is not None
+            else self._get_cached_intervals(start_time_iso, end_time_iso)
+        )
 
         # Track if API was called (True if any missing ranges were attempted)
         # If fetch failed but we fell back to cache, treat as "no API call succeeded"
@@ -551,6 +625,58 @@ class TibberPricesIntervalPool:
 
         return None
 
+    def _covers_current_interval(self, intervals: list[dict[str, Any]]) -> bool:
+        """
+        Return True if the cached intervals cover the current moment.
+
+        This is the resilience threshold used during Tibber API outages: as long
+        as we still have a price interval for "now", the integration can keep
+        serving sensors from locally cached data instead of failing to load.
+        Only when the current interval is missing do we treat the cache as
+        unusable and let the caller raise (alarm).
+
+        Args:
+            intervals: Cached interval dicts (each with a "startsAt" field).
+
+        Returns:
+            True if an interval covering the current time exists, False otherwise.
+
+        """
+        if not intervals:
+            return False
+
+        now = self._time_service.now() if self._time_service else dt_util.now()
+
+        # Collect interval start datetimes (startsAt may be ISO string or datetime)
+        starts: list[datetime] = []
+        for interval in intervals:
+            starts_at = interval.get("startsAt")
+            if starts_at is None:
+                continue
+            start_dt = starts_at if isinstance(starts_at, datetime) else dt_util.parse_datetime(starts_at)
+            if start_dt is not None:
+                starts.append(start_dt)
+
+        if not starts:
+            return False
+
+        starts.sort()
+
+        # An interval covers "now" if start <= now < start + length. The length is
+        # derived from the gap to the next interval, capped at one hour so a large
+        # gap (missing data) cannot falsely report coverage. This handles both
+        # quarter-hourly (15 min) and hourly (60 min) resolutions.
+        max_length = timedelta(minutes=INTERVAL_HOURLY)
+        for index, start_dt in enumerate(starts):
+            if index + 1 < len(starts):
+                length = min(starts[index + 1] - start_dt, max_length)
+            else:
+                length = max_length
+            if start_dt <= now < start_dt + length:
+                return True
+
+        return False
+
     def _get_cached_intervals(
         self,
         start_time_iso: str,

custom_components/tibber_prices/services/find_cheapest_block.py

@@ -30,6 +30,7 @@ from .helpers import (
     PRICE_LEVEL_ORDER,
     VALID_SEARCH_SCOPES,
     apply_must_finish_by,
+    async_fetch_service_intervals,
     build_rating_lookup,
     build_response_interval,
     calculate_search_range_avg,
@@ -310,25 +311,42 @@ async def _handle_find_block(
     user_data = coordinator._cached_user_data  # noqa: SLF001
     pool = entry.runtime_data.interval_pool
 
-    try:
+    price_info, fetch_ok = await async_fetch_service_intervals(
-        price_info, _api_called = await pool.get_intervals(
+        pool,
         api_client=api_client,
         user_data=user_data,
         start_time=search_start,
         end_time=search_end,
+        service_label=service_label,
     )
-    except Exception as error:
-        _LOGGER.exception("Error fetching price data for %s", service_label)
-        raise ServiceValidationError(
-            translation_domain=DOMAIN,
-            translation_key="price_fetch_failed",
-        ) from error
 
     # Determine currency and unit
     currency = entry.data.get("currency", "EUR")
     unit_factor = 1 if use_base_unit else get_display_unit_factor(entry)
     price_unit = f"{currency}/kWh" if use_base_unit else get_display_unit_string(entry, currency)
 
+    if not fetch_ok:
+        # Price data unavailable (API outage on uncached range). Return a well-formed
+        # empty response with success=False so automations can detect this directly.
+        unavailable: dict[str, Any] = {
+            "success": False,
+            "reason": "price_data_unavailable",
+            "home_id": home_id,
+            "search_start": search_start.isoformat(),
+            "search_end": search_end.isoformat(),
+            "must_finish_by": must_finish_by_dt.isoformat() if must_finish_by_dt else None,
+            "duration_minutes_requested": duration_minutes_requested,
+            "duration_minutes": duration_minutes_requested,
+            "currency": currency,
+            "price_unit": price_unit,
+            "window_found": False,
+            "relaxation_applied": False,
+            "window": None,
+        }
+        if resolved_refs:
+            unavailable["_resolved"] = resolved_refs
+        return unavailable
+
     # --- Attempt with original parameters ---
     effective_duration = duration_intervals
     result, reason = _attempt_find_block(
@@ -393,6 +411,7 @@ async def _handle_find_block(
             len(price_info),
         )
         response: dict[str, Any] = {
+            "success": True,
             "home_id": home_id,
             "search_start": search_start.isoformat(),
             "search_end": search_end.isoformat(),
@@ -452,6 +471,7 @@ async def _handle_find_block(
     seconds_until_end = max(0, int((end_time_dt - now).total_seconds()))
 
     response = {
+        "success": True,
         "home_id": home_id,
         "search_start": search_start.isoformat(),
         "search_end": search_end.isoformat(),

custom_components/tibber_prices/services/find_cheapest_hours.py

@@ -27,6 +27,7 @@ from .helpers import (
     PRICE_LEVEL_ORDER,
     VALID_SEARCH_SCOPES,
     apply_must_finish_by,
+    async_fetch_service_intervals,
     build_rating_lookup,
     build_response_interval,
     calculate_search_range_avg,
@@ -267,6 +268,7 @@ def _build_found_response(
     )
 
     return {
+        "success": True,
         "home_id": home_id,
         "search_start": search_start.isoformat(),
         "search_end": search_end.isoformat(),
@@ -382,25 +384,44 @@ async def _handle_find_hours(
     user_data = coordinator._cached_user_data  # noqa: SLF001
     pool = entry.runtime_data.interval_pool
 
-    try:
+    price_info, fetch_ok = await async_fetch_service_intervals(
-        price_info, _api_called = await pool.get_intervals(
+        pool,
         api_client=api_client,
         user_data=user_data,
         start_time=search_start,
         end_time=search_end,
+        service_label=service_label,
     )
-    except Exception as error:
-        _LOGGER.exception("Error fetching price data for %s", service_label)
-        raise ServiceValidationError(
-            translation_domain=DOMAIN,
-            translation_key="price_fetch_failed",
-        ) from error
 
     # Determine currency and unit
     currency = entry.data.get("currency", "EUR")
     unit_factor = 1 if use_base_unit else get_display_unit_factor(entry)
     price_unit = f"{currency}/kWh" if use_base_unit else get_display_unit_string(entry, currency)
 
+    if not fetch_ok:
+        # Price data unavailable (API outage on uncached range). Return a well-formed
+        # empty response with success=False so automations can detect this directly.
+        unavailable: dict[str, Any] = {
+            "success": False,
+            "reason": "price_data_unavailable",
+            "home_id": home_id,
+            "search_start": search_start.isoformat(),
+            "search_end": search_end.isoformat(),
+            "must_finish_by": must_finish_by_dt.isoformat() if must_finish_by_dt else None,
+            "total_minutes_requested": total_minutes_requested,
+            "total_minutes": total_minutes_requested,
+            "min_segment_minutes_requested": min_segment_minutes_requested,
+            "min_segment_minutes": min_segment_minutes,
+            "currency": currency,
+            "price_unit": price_unit,
+            "intervals_found": False,
+            "relaxation_applied": False,
+            "schedule": None,
+        }
+        if resolved_refs:
+            unavailable["_resolved"] = resolved_refs
+        return unavailable
+
     # --- Attempt with original parameters ---
     effective_total = total_intervals
     result, reason = _attempt_find_hours(
@@ -467,6 +488,7 @@ async def _handle_find_hours(
             len(price_info),
         )
         response: dict[str, Any] = {
+            "success": True,
             "home_id": home_id,
             "search_start": search_start.isoformat(),
             "search_end": search_end.isoformat(),

custom_components/tibber_prices/services/find_cheapest_schedule.py

@@ -30,6 +30,7 @@ from .helpers import (
     PRICE_LEVEL_ORDER,
     VALID_SEARCH_SCOPES,
     apply_must_finish_by,
+    async_fetch_service_intervals,
     build_rating_lookup,
     build_response_interval,
     filter_intervals_by_price_level,
@@ -479,24 +480,42 @@ async def handle_find_cheapest_schedule(call: ServiceCall) -> ServiceResponse:
     user_data = coordinator._cached_user_data  # noqa: SLF001
     pool = entry.runtime_data.interval_pool
 
-    try:
+    price_info, fetch_ok = await async_fetch_service_intervals(
-        price_info, _api_called = await pool.get_intervals(
+        pool,
         api_client=api_client,
         user_data=user_data,
         start_time=search_start,
         end_time=search_end,
+        service_label=service_label,
     )
-    except Exception as error:
-        _LOGGER.exception("Error fetching price data for %s", service_label)
-        raise ServiceValidationError(
-            translation_domain=DOMAIN,
-            translation_key="price_fetch_failed",
-        ) from error
 
     currency = entry.data.get("currency", "EUR")
     unit_factor = 1 if use_base_unit else get_display_unit_factor(entry)
     price_unit = f"{currency}/kWh" if use_base_unit else get_display_unit_string(entry, currency)
 
+    if not fetch_ok:
+        # Price data unavailable (API outage on uncached range). Return a well-formed
+        # empty response with success=False so automations can detect this directly.
+        unavailable: dict[str, Any] = {
+            "success": False,
+            "reason": "price_data_unavailable",
+            "home_id": home_id,
+            "search_start": search_start.isoformat(),
+            "search_end": search_end.isoformat(),
+            "must_finish_by": must_finish_by_dt.isoformat() if must_finish_by_dt else None,
+            "currency": currency,
+            "price_unit": price_unit,
+            "sequential": sequential,
+            "all_tasks_scheduled": False,
+            "relaxation_applied": False,
+            "unscheduled_tasks": None,
+            "tasks": [],
+            "total_estimated_cost": None,
+        }
+        if resolved_refs:
+            unavailable["_resolved"] = resolved_refs
+        return unavailable
+
     # --- Attempt with original parameters ---
     raw_assignments, unscheduled, filtered = _attempt_schedule(
         price_info,
@@ -676,6 +695,7 @@ async def handle_find_cheapest_schedule(call: ServiceCall) -> ServiceResponse:
         task_entry["seconds_until_end"] = max(0, int((task_end_dt - now).total_seconds()))
 
     result: dict[str, Any] = {
+        "success": True,
         "home_id": home_id,
         "search_start": search_start.isoformat(),
         "search_end": search_end.isoformat(),

custom_components/tibber_prices/services/get_price.py

@@ -25,7 +25,7 @@ from homeassistant.helpers import config_validation as cv
 from homeassistant.util import dt as dt_util
 
 from .entity_resolver import or_entity_ref, resolve_entity_references
-from .helpers import get_entry_and_data
+from .helpers import async_fetch_service_intervals, get_entry_and_data
 
 if TYPE_CHECKING:
     from homeassistant.core import HomeAssistant, ServiceCall, ServiceResponse
@@ -150,31 +150,41 @@ async def handle_get_price(call: ServiceCall) -> ServiceResponse:
         end_time,
     )
 
-    try:
     # Get interval pool from entry runtime_data (one pool per config entry)
     pool = entry.runtime_data.interval_pool
 
-        # Call the interval pool to get intervals (with intelligent caching)
+    # Resilient fetch: never impairs sensors, returns empty result on API failure
-        # Single-home architecture: pool knows its home_id, no parameter needed
+    # instead of raising. Single-home architecture: pool knows its home_id.
-        price_info, _api_called = await pool.get_intervals(
+    price_info, fetch_ok = await async_fetch_service_intervals(
+        pool,
         api_client=api_client,
         user_data=user_data,
         start_time=start_time,
         end_time=end_time,
+        service_label="get_price",
     )
-        # Note: We ignore api_called flag here - service always returns requested data
-        # regardless of whether it came from cache or was fetched fresh from API
 
-    except Exception as error:
+    if not fetch_ok:
-        _LOGGER.exception("Error fetching price data")
+        # Price data could not be fetched (API outage on an uncached range). Return a
-        raise ServiceValidationError(
+        # well-formed empty response with success=False so automations can detect this
-            translation_domain=DOMAIN,
+        # without inspecting the data fields.
-            translation_key="price_fetch_failed",
+        response = {
-        ) from error
+            "success": False,
+            "reason": "price_data_unavailable",
+            "home_id": home_id,
+            "start_time": start_time.isoformat(),
+            "end_time": end_time.isoformat(),
+            "interval_count": 0,
+            "price_info": [],
+        }
+        if resolved_refs:
+            response["_resolved"] = resolved_refs
+        _LOGGER.info("get_price service completed: price data unavailable")
+        return response
 
-    else:
     # Add metadata to response
     response = {
+        "success": True,
         "home_id": home_id,
         "start_time": start_time.isoformat(),
         "end_time": end_time.isoformat(),

custom_components/tibber_prices/services/helpers.py

@@ -31,8 +31,13 @@ Used by:
 from __future__ import annotations
 
 from datetime import datetime, time as dt_time, timedelta
+import logging
 from typing import TYPE_CHECKING, Any
 
+from custom_components.tibber_prices.api.exceptions import (
+    TibberPricesApiClientAuthenticationError,
+    TibberPricesApiClientError,
+)
 from custom_components.tibber_prices.const import DOMAIN
 from custom_components.tibber_prices.coordinator.helpers import get_intervals_for_day_offsets
 from homeassistant.exceptions import ServiceValidationError
@@ -42,8 +47,11 @@ if TYPE_CHECKING:
     from zoneinfo import ZoneInfo
 
     from custom_components.tibber_prices.coordinator import TibberPricesDataUpdateCoordinator
+    from custom_components.tibber_prices.interval_pool import TibberPricesIntervalPool
     from homeassistant.core import HomeAssistant
 
+_LOGGER = logging.getLogger(__name__)
+
 # Interval duration in minutes (quarter-hourly resolution)
 INTERVAL_MINUTES = 15
 
@@ -259,6 +267,69 @@ def get_entry_and_data(hass: HomeAssistant, entry_id: str) -> tuple[Any, Any, di
     return entry, coordinator, data
 
 
+async def async_fetch_service_intervals(
+    pool: TibberPricesIntervalPool,
+    *,
+    api_client: Any,
+    user_data: dict[str, Any] | None,
+    start_time: datetime,
+    end_time: datetime,
+    service_label: str,
+) -> tuple[list[dict[str, Any]], bool]:
+    """
+    Fetch price intervals for a service request resiliently.
+
+    Shared, resilient wrapper around the interval pool used by every price-query
+    service. It guarantees two things the raw pool call does not:
+
+    1. Sensor isolation: passes track_degraded=False so a service request can never
+       flip the pool's degraded-state flags (which govern sensor availability). A
+       failing or succeeding service fetch therefore has zero effect on sensor health.
+    2. Graceful failure: on a transient API/data error the helper returns
+       ([], False) instead of raising, so the service can still return a well-formed
+       response (possibly with empty contents) for automations to consume.
+
+    Authentication errors are re-raised unchanged so the coordinator can trigger the
+    reauth flow.
+
+    Args:
+        pool: The config entry's interval pool.
+        api_client: TibberPricesApiClient instance.
+        user_data: Cached user data dict (may be None during early setup).
+        start_time: Start of range (inclusive, timezone-aware).
+        end_time: End of range (exclusive, timezone-aware).
+        service_label: Human-readable service name for logging.
+
+    Returns:
+        Tuple of (intervals, fetch_ok):
+        - intervals: Price intervals for the range. Empty list on failure.
+        - fetch_ok: True if the data was available, False if an API error
+          prevented fetching the requested (uncached) range.
+
+    Raises:
+        TibberPricesApiClientAuthenticationError: If authentication failed.
+
+    """
+    try:
+        intervals, _api_called = await pool.get_intervals(
+            api_client=api_client,
+            user_data=user_data or {},
+            start_time=start_time,
+            end_time=end_time,
+            track_degraded=False,
+        )
+    except TibberPricesApiClientAuthenticationError:
+        raise
+    except TibberPricesApiClientError as err:
+        _LOGGER.warning(
+            "%s: price data unavailable (%s) - returning empty result so sensors stay unaffected",
+            service_label,
+            err,
+        )
+        return [], False
+    return intervals, True
+
+
 def has_tomorrow_data(coordinator: TibberPricesDataUpdateCoordinator) -> bool:
     """
     Check if tomorrow's price data is available in coordinator.

custom_components/tibber_prices/services/plan_charging.py

@@ -39,6 +39,7 @@ from .helpers import (
     PRICE_LEVEL_ORDER,
     VALID_SEARCH_SCOPES,
     apply_must_finish_by,
+    async_fetch_service_intervals,
     build_rating_lookup,
     build_response_interval,
     calculate_search_range_avg,
@@ -660,6 +661,7 @@ async def handle_plan_charging(call: ServiceCall) -> ServiceResponse:
         currency = entry.data.get("currency", "EUR")
         price_unit = f"{currency}/kWh" if use_base_unit else get_display_unit_string(entry, currency)
         response: dict[str, Any] = {
+            "success": True,
             "home_id": entry.data.get("home_id", ""),
             "intervals_found": False,
             "reason": "already_at_target",
@@ -742,19 +744,45 @@ async def handle_plan_charging(call: ServiceCall) -> ServiceResponse:
     api_client = coordinator.api
     user_data = coordinator._cached_user_data  # noqa: SLF001
     pool = entry.runtime_data.interval_pool
-    try:
+    price_info, fetch_ok = await async_fetch_service_intervals(
-        price_info, _api_called = await pool.get_intervals(
+        pool,
         api_client=api_client,
         user_data=user_data,
         start_time=search_start,
         end_time=search_end,
+        service_label=PLAN_CHARGING_SERVICE_NAME,
     )
-    except Exception as error:
+
-        _LOGGER.exception("Error fetching price data for %s", PLAN_CHARGING_SERVICE_NAME)
+    if not fetch_ok:
-        raise ServiceValidationError(
+        # Price data unavailable (API outage on uncached range). Return a well-formed
-            translation_domain=DOMAIN,
+        # empty response with success=False so automations can detect this directly.
-            translation_key="price_fetch_failed",
+        unavailable: dict[str, Any] = {
-        ) from error
+            "success": False,
+            "reason": "price_data_unavailable",
+            "home_id": home_id,
+            "search_start": search_start.isoformat(),
+            "search_end": search_end.isoformat(),
+            "must_finish_by": must_finish_by_dt.isoformat() if must_finish_by_dt else None,
+            "intervals_found": False,
+            "battery": _build_battery_info(
+                current_soc_kwh=current_soc_kwh,
+                target_soc_kwh=target_soc_kwh,
+                capacity_kwh=capacity_kwh,
+                requested_energy_needed_kwh=requested_energy_needed_grid_kwh,
+                charging_efficiency=charging_efficiency,
+                achieved_soc_kwh=current_soc_kwh,
+                must_reach_soc_kwh=must_reach_soc_kwh,
+            ),
+            "charging": None,
+            "deadline": {"must_reach_by": deadline.isoformat(), "source": deadline_source} if deadline else None,
+            "economics": None,
+            "currency": currency,
+            "price_unit": price_unit,
+            "relaxation_applied": False,
+        }
+        if resolved_refs:
+            unavailable["_resolved"] = resolved_refs
+        return unavailable
 
     plan_ctx = _PlanContext(
         price_info=price_info,
@@ -824,6 +852,7 @@ async def handle_plan_charging(call: ServiceCall) -> ServiceResponse:
 
     if planning_result is None:
         response: dict[str, Any] = {
+            "success": True,
             "home_id": home_id,
             "search_start": search_start.isoformat(),
             "search_end": search_end.isoformat(),
@@ -930,6 +959,7 @@ async def handle_plan_charging(call: ServiceCall) -> ServiceResponse:
             )
 
     response: dict[str, Any] = {
+        "success": True,
         "home_id": home_id,
         "search_start": search_start.isoformat(),
         "search_end": search_end.isoformat(),