feat: reject bubble soak/pre-wash/intensive writes on unsupported courses

Add a validate_fn hook to SwitchDesc, checked in switch.py before dispatch
and surfaced as a ServiceValidationError so an unsupported write shows a
real error in the UI instead of the coordinator's silent log-only rejection.

Wired it into the three course-gated washer switches using their
availability bitmaps (BubbleSoakSet/PreWashAvailableSet/IntensiveAvailableSet),
which line up positionally with editCourseList. Turning a toggle off is
never blocked, and the check fails open whenever the course or bitmap can't
be resolved.

Also fixes a bug in _bool_option_write: it took a `p and 'On' or 'Off'`-style
truthy check, but switch.py always calls it with the string 'On' or 'Off' --
both truthy, so every write landed as 'On' regardless of intent.

custom_components/localthings/registry/capabilities/washer.py

@@ -17,7 +17,7 @@ from datetime import datetime, timezone
 
 from ..capability import Capability
 from ..entities import BinarySensorDesc, SelectDesc, SensorDesc, SwitchDesc
-from .laundry import cycle_select, hex_pairs, option_value, replace_in_options
+from .laundry import cycle_options, cycle_select, hex_pairs, option_value, replace_in_options
 
 # ---------------------------------------------------------------------------
 # Course_XX hex codes. 23 of the codes named in strings.json/translations
@@ -245,25 +245,27 @@ def _dosing_alarm_exists(prefix):
 # already used by AiOption and KidsLockBypass in this same array, so
 # PreWashSetting/IntensiveSetting are assumed to follow suit.
 #
-# Each also has a same-shaped '<Prefix>Set'/'<Prefix>AvailableSet' hex-pair
-# string that lines up positionally with editCourseList -- e.g. on the combo
-# dump, BubbleSoakSet's byte for the active course (Course_1C, position 0)
-# is '00' while PreWashAvailableSet/IntensiveAvailableSet are both 'F0',
-# suggesting F0/00 is an available/unavailable flag per course. That's not
-# exposed here: exists_fn only runs once, against the setup-time snapshot
-# (see entity._is_included), so gating on the *current* course would just
-# make the entity's existence depend on whatever course happened to be
-# selected when Home Assistant started, not on the device's real, static
-# capability. Toggling one of these on a course the app would gray it out
-# for is untested; treat it like any other write this integration doesn't
-# validate against device-side state.
+# Each also has a differently-named hex-pair availability field that lines up
+# positionally with editCourseList: BubbleSoakSet, PreWashAvailableSet,
+# IntensiveAvailableSet. On the reporter's dump (course '30' at position 1 of
+# 24), all three read 'F0' at that position and the toggle was writable --
+# and the same dump's earlier state (course '1C' at position 0, 'BubbleSoak
+# Off') decodes to '00' for that course, matching the app graying the
+# control out there. 'F0'/'00' is treated as available/unavailable on that
+# evidence. exists_fn (device-level presence) still only runs once, against
+# the setup-time snapshot, so it isn't a fit for this per-course check --
+# validate_fn runs on every write attempt instead, rejecting an on-write for
+# a course whose byte isn't 'F0' with a user-facing error rather than
+# silently no-opping against the device.
 def _bool_option_write(prefix):
     def write(p, rep, href=None):
+        if p not in ('On', 'Off'):
+            return None
         opts = list(rep.get('x.com.samsung.da.options') or [])
         if not opts:
             return None
         return ['course', 'vs', '0'], {
-            'x.com.samsung.da.options': replace_in_options(opts, prefix, 'On' if p else 'Off'),
+            'x.com.samsung.da.options': replace_in_options(opts, prefix, p),
         }
     return write
 
@@ -277,6 +279,41 @@ def _bool_option_exists(prefix):
         rep.get('x.com.samsung.da.options'), prefix) is not None
 
 
+_AVAILABILITY_FIELD = {
+    'BubbleSoak': 'BubbleSoakSet',
+    'PreWashSetting': 'PreWashAvailableSet',
+    'IntensiveSetting': 'IntensiveAvailableSet',
+}
+
+
+def _bool_option_validate(prefix, human_name):
+    """Reject turning `prefix` on when the selected course's byte in its
+    availability bitmap isn't 'F0'. Turning off is never blocked. Falls back
+    to allowing the write whenever the availability data can't be resolved
+    (unrecognized course, missing/mismatched-length bitmap) rather than
+    guessing -- a false rejection is worse than an occasional no-op write."""
+    availability_field = _AVAILABILITY_FIELD[prefix]
+
+    def validate(p, rep, resources):
+        if p != 'On':
+            return None
+        opts = rep.get('x.com.samsung.da.options') or []
+        current = option_value(opts, 'Course')
+        courses = cycle_options(resources)
+        if not current or current not in courses:
+            return None
+        raw = option_value(opts, availability_field)
+        if raw is None:
+            return None
+        pairs = hex_pairs(raw)
+        if len(pairs) != len(courses):
+            return None
+        if pairs[courses.index(current)] != 'F0':
+            return f"{human_name} isn't available on the selected cycle."
+        return None
+    return validate
+
+
 WASHER_COURSE = Capability(
     href='/course/vs/0',
     entities=(
@@ -337,16 +374,19 @@ WASHER_COURSE = Capability(
                    entity_category='config',
                    exists_fn=_bool_option_exists('BubbleSoak'),
                    rep_fn=_bool_option_value('BubbleSoak'),
-                   write_fn=_bool_option_write('BubbleSoak')),
+                   write_fn=_bool_option_write('BubbleSoak'),
+                   validate_fn=_bool_option_validate('BubbleSoak', 'Bubble soak')),
         SwitchDesc(key='pre_wash', name='Pre wash', icon='mdi:washing-machine',
                    entity_category='config',
                    exists_fn=_bool_option_exists('PreWashSetting'),
                    rep_fn=_bool_option_value('PreWashSetting'),
-                   write_fn=_bool_option_write('PreWashSetting')),
+                   write_fn=_bool_option_write('PreWashSetting'),
+                   validate_fn=_bool_option_validate('PreWashSetting', 'Pre wash')),
         SwitchDesc(key='intensive', name='Intensive', icon='mdi:washing-machine',
                    entity_category='config',
                    exists_fn=_bool_option_exists('IntensiveSetting'),
                    rep_fn=_bool_option_value('IntensiveSetting'),
-                   write_fn=_bool_option_write('IntensiveSetting')),
+                   write_fn=_bool_option_write('IntensiveSetting'),
+                   validate_fn=_bool_option_validate('IntensiveSetting', 'Intensive')),
     ),
 )

custom_components/localthings/registry/entities.py

@@ -2,7 +2,9 @@
 
 Frozen dataclasses so the future native HA component can consume them as
 EntityDescription subclasses unchanged. Read transforms live in value_fn;
-presence gating in exists_fn; write logic in write_fn on command platforms.
+presence gating in exists_fn; write logic in write_fn on command platforms;
+pre-write rejection (surfaced to the user, not just logged) in validate_fn
+where a description declares one.
 """
 from __future__ import annotations
 
@@ -10,6 +12,11 @@ from dataclasses import dataclass, field
 from typing import Any, Callable, Optional
 
 WriteFn = Optional[Callable[[Any, dict], "tuple[list[str], dict] | None"]]
+# (payload, rep, resources) -> a human-readable rejection message, or None to
+# allow the write. resources is the coordinator's full href->rep snapshot, for
+# the same cross-resource lookups exists_fn needs (e.g. reading a sibling
+# href's live option list).
+ValidateFn = Optional[Callable[[Any, dict, dict], "str | None"]]
 
 
 def _identity(v: Any) -> Any:
@@ -61,6 +68,7 @@ class SelectDesc(SamsungEntityDescription):
 class SwitchDesc(SamsungEntityDescription):
     device_class: Optional[str] = None
     write_fn: WriteFn = None
+    validate_fn: ValidateFn = None
 
 
 @dataclass(frozen=True, kw_only=True)

custom_components/localthings/switch.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 from homeassistant.components.switch import SwitchEntity
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.core import HomeAssistant
+from homeassistant.exceptions import ServiceValidationError
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 
 from .registry.entities import SwitchDesc
@@ -38,7 +39,16 @@ class LocalThingsSwitch(LocalThingsEntity, SwitchEntity):
         return (self.coordinator.data or {}).get(self._state_key)
 
     async def async_turn_on(self, **kwargs) -> None:
-        await self.coordinator.async_send_command(self._bound, 'On')
+        await self._send('On')
 
     async def async_turn_off(self, **kwargs) -> None:
-        await self.coordinator.async_send_command(self._bound, 'Off')
+        await self._send('Off')
+
+    async def _send(self, payload: str) -> None:
+        desc: SwitchDesc = self._bound.desc
+        if desc.validate_fn is not None:
+            rep = self.coordinator.last_resources.get(self._bound.href) or {}
+            error = desc.validate_fn(payload, rep, self.coordinator.last_resources)
+            if error:
+                raise ServiceValidationError(error)
+        await self.coordinator.async_send_command(self._bound, payload)