Stop double-converting filterUsage on AIR_FILTER/HEPA_FILTER (#330)

filterUsage is already a 0-100 percentage on every confirmed family,
including ARTIK051_PRAC: filterStatus flips to 'wash' at
filterUsage == '100' regardless of filterCapacity (60/224/500 across
other fixtures), which only holds if filterUsage is already a percent.
filter_usage_percent() divided by filterCapacity again, reading a
filter due for washing as 20% fresh.

air_filter_usage_hours had the mirror problem: it read filterUsage
directly as an hour count with device_class=duration, when the field
is a percent. It's now derived from the percentage and filterCapacity
(new filter_usage_hours() in common.py) instead.

custom_components/localthings/registry/capabilities/airconditioner.py

@@ -22,7 +22,7 @@ from ..entities import (
     SwitchDesc,
 )
 from . import common
-from .common import filter_usage_percent, normalize_temp_unit
+from .common import filter_usage_hours, filter_usage_percent, normalize_temp_unit
 from .laundry import option_write
 
 
@@ -854,16 +854,17 @@ AIR_FILTER = Capability(
             icon="mdi:air-filter",
             entity_category="diagnostic",
         ),
-        # Lifetime hour counter, resets only on filter replacement.
+        # Lifetime hour counter, resets only on filter replacement. Derived
+        # from the percentage and filterCapacity (issue #330) -- filterUsage
+        # itself is not an hour count.
         SensorDesc(
             key="air_filter_usage_hours",
-            field="x.com.samsung.da.filterUsage",
+            rep_fn=filter_usage_hours,
             device_class="duration",
             state_class="total_increasing",
             unit_fn=_filter_unit,
             icon="mdi:air-filter",
             entity_category="diagnostic",
-            value_fn=_int,
         ),
         # Locally writable alarm threshold (see _threshold_write); only
         # surfaces where supportedFilterDesiredUsage is advertised.
@@ -925,13 +926,12 @@ AIR_FILTER_PM1 = Capability(
         ),
         SensorDesc(
             key="air_filter_pm1_usage_hours",
-            field="x.com.samsung.da.filterUsage",
+            rep_fn=filter_usage_hours,
             device_class="duration",
             state_class="total_increasing",
             unit_fn=_filter_unit,
             icon="mdi:air-filter",
             entity_category="diagnostic",
-            value_fn=_int,
             exists_fn=_has_filter_field("x.com.samsung.da.filterUsage"),
         ),
         SelectDesc(

custom_components/localthings/registry/capabilities/common.py

@@ -72,15 +72,25 @@ def epoch_to_utc(value):
 
 
 def filter_usage_percent(rep):
-    """Filter usage as a percentage of rated capacity. Several families
-    report `filterUsage` as a raw count in `filterCapacityUnit` (e.g. 100 of
-    a 500-hour capacity), so a plain value with a '%' unit would be wrong.
-    Returns None when capacity is missing/zero."""
-    used = _num(rep.get("x.com.samsung.da.filterUsage"))
+    """Filter usage as a percentage. `filterUsage` is already 0-100 on every
+    family confirmed so far, including ARTIK051_PRAC (issue #330): its own
+    fixture and three live heads all show `filterStatus == 'wash'` at
+    `filterUsage == '100'` regardless of `filterCapacity` (60/224/500 across
+    other families' fixtures), which only holds if `filterUsage` is already
+    a percent -- dividing by capacity again would read that filter as fresh
+    at 20%."""
+    return int_or_none(rep.get("x.com.samsung.da.filterUsage"))
+
+
+def filter_usage_hours(rep):
+    """Elapsed filter hours, derived from the percentage and capacity rather
+    than read off `filterUsage` directly -- `filterUsage` is a percent, not
+    an hour count (issue #330). Returns None when capacity is missing/zero."""
+    pct = filter_usage_percent(rep)
     cap = _num(rep.get("x.com.samsung.da.filterCapacity"))
-    if used is None or not cap:
+    if pct is None or not cap:
         return None
-    return round(used / cap * 100)
+    return round(pct / 100 * cap, 1)
 
 
 def normalize_temp_unit(raw, default="°F"):