AC: quantize subdevice temperature writes against their own step (Opus review)

async_send_command handed write_fn/validate_fn the raw cache snapshot
(real, on-the-wire hrefs), not a subdevice-scoped view. Every other
consumer of a full resources dict (exists_fn, rep_fn, is_legacy_board,
...) reads through coordinator.canonical_resources() specifically to
avoid this; write_fn/validate_fn didn't, so on a composite AC (issue
#177) _temperature_step's resources.get(HREF_TEMP_CONTROL) saw the
master's /temperature/control/vs/0 instead of the subdevice's own
/temperature/control/vs/1, silently rounding a subdevice's 0.5-degree
write to a whole degree. The remote-control gate stays on the raw
snapshot -- /remotectrl/* is a shared, MAIN-only resource a
subdevice's owned-hrefs-only canonical view would drop entirely.

climate.py's target_temperature_step duplicated this same
read-in-order logic; pointed it at airconditioner._temperature_step
so the read and write paths can't drift again.

Also, from the same review:
- _quantize_temperature rejects non-finite floats (nan/inf survive
  float() but raise out of round()/division, escaping write_fn's
  documented None-on-bad-payload contract).
- Deduplicated the quantize-and-check block shared by the
  temperature_ocf/temperature branches of _climate_write.
- Added the /temperatures/vs/0 items[]-fallback test that was
  previously unreachable (every increment-carrying fixture also has
  /temperature/control/vs/0, which _temperature_step checks first).
- Added a coordinator-level test seeding an indexed subdevice with its
  own step, distinct from the master's, covering the fix above.
- The Towels/Bedding regression test now checks all 7 locale catalogs,
  not just English -- the bug is a code-mapping error, and
  test_every_language_mirrors_the_english_catalog only checks key
  topology, not values.

custom_components/localthings/climate.py

@@ -58,9 +58,6 @@ from .registry.capabilities.airconditioner import (
 from .registry.capabilities.airconditioner import (
     HREF_POWER_VS as POWER_VS_HREF,
 )
-from .registry.capabilities.airconditioner import (
-    HREF_TEMP_CONTROL as TEMP_CONTROL_HREF,
-)
 from .registry.capabilities.airconditioner import (
     HREF_TEMP_CURRENT as TEMP_CURRENT_HREF,
 )
@@ -80,6 +77,7 @@ from .registry.capabilities.airconditioner import (
     HREF_WIND_STRENGTH as WIND_STRENGTH_HREF,
 )
 from .registry.capabilities.airconditioner import (
+    _temperature_step,
     extend_option_code_bit,
     has_extend_option_code,
     has_option_code,
@@ -558,12 +556,11 @@ class LocalThingsClimate(LocalThingsEntity, ClimateEntity):
 
     @property
     def target_temperature_step(self) -> float:
-        return (
-            _num(self._rep(TEMP_CONTROL_HREF).get("increment"))
-            or _num(self._rep(TEMP_CONTROL_HREF).get("x.com.samsung.da.increment"))
-            or _num(self._temps_vs().get("x.com.samsung.da.increment"))
-            or 1.0
-        )
+        # Shared with the write path (airconditioner._climate_write) so a
+        # step read here always matches the step a write is quantized to --
+        # self._resources is this entity's own subdevice's canonical view
+        # (issue #177), the same shape _temperature_step expects.
+        return _temperature_step(self._resources) or 1.0
 
     # -- hvac mode ----------------------------------------------------------
 

custom_components/localthings/coordinator.py

@@ -1186,17 +1186,28 @@ class LocalThingsCoordinator(DataUpdateCoordinator[dict[str, Any]]):
             return
         href = bound_entity.href
         rep = self._cache.get(href or "") or {}
-        resources = self._cache.snapshot()
+        # The remote-control gate below keys off the raw on-the-wire href
+        # and a raw snapshot -- /remotectrl/* is a shared, MAIN-only
+        # resource that a subdevice's canonical_resources() view (owned
+        # hrefs only) would drop entirely. write_fn/validate_fn, by
+        # contrast, are written against canonical hrefs (same convention as
+        # exists_fn/rep_fn -- see entity.py's _resources), so they get this
+        # entity's own subdevice view instead of the raw snapshot: without
+        # it, a composite device's write_fn reading resources.get(some
+        # canonical href) (e.g. airconditioner._temperature_step) would
+        # silently see the master's resource instead of its own subdevice's.
+        raw_resources = self._cache.snapshot()
         bypass_remote_control = self._entry.options.get(CONF_BYPASS_REMOTE_CONTROL, False)
         if (
             not bypass_remote_control
-            and remote_control_required_for_write(resources, href or "")
-            and not remote_control_enabled(resources)
+            and remote_control_required_for_write(raw_resources, href or "")
+            and not remote_control_enabled(raw_resources)
         ):
             raise ServiceValidationError(
                 translation_domain=DOMAIN,
                 translation_key="remote_control_disabled",
             )
+        resources = self.canonical_resources(bound_entity.subdevice)
         validate_fn = getattr(desc, "validate_fn", None)
         if validate_fn is not None:
             error = validate_fn(payload, rep, resources)

custom_components/localthings/registry/capabilities/airconditioner.py

@@ -9,6 +9,7 @@ here off the coordinator snapshot. These caps stay out of the global
 capabilities/__init__.py) -- AC-only, by_type registry only.
 """
 
+import math
 from dataclasses import replace
 
 from ..capability import Capability
@@ -510,6 +511,13 @@ def _quantize_temperature(value, step):
         numeric = float(value)
     except (TypeError, ValueError):
         return None
+    if not math.isfinite(numeric):
+        # float('nan')/float('inf') pass the try/except above (they're
+        # valid floats) but round()/division on them raises ValueError/
+        # OverflowError instead of returning -- reject here so a bad
+        # payload always comes back as a clean None, not an exception
+        # out of write_fn.
+        return None
     step_value = _num(step) or 1.0
     if step_value <= 0:
         step_value = 1.0
@@ -558,16 +566,13 @@ def _climate_write(payload, rep, href=None, resources=None):
         return (["power", "vs", "0"], {"x.com.samsung.da.power": "On" if value else "Off"})
     if kind == "mode":
         return (["mode", "vs", "0"], {"x.com.samsung.da.modes": [value]})
-    if kind == "temperature_ocf":
+    if kind in ("temperature_ocf", "temperature"):
         quantized = _quantize_temperature(value, _temperature_step(resources))
         if quantized is None:
             return None
-        return (["temperature", "desired", "0"], {"temperature": quantized})
-    if kind == "temperature":
+        if kind == "temperature_ocf":
+            return (["temperature", "desired", "0"], {"temperature": quantized})
         # Vendor items[] array; only one item observed on every AC dump, id '0'.
-        quantized = _quantize_temperature(value, _temperature_step(resources))
-        if quantized is None:
-            return None
         return (
             ["temperatures", "vs", "0"],
             {