From 5373412f6028b9c6dcd9a81fe187aa175909af83 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 3 Mar 2026 12:03:51 -1000
Subject: [PATCH] move DEVICE_CLASS_MAX_LENGTH to esphome/core/config.py
 alongside other max length constants

---
 esphome/config_validation.py   | 5 -----
 esphome/core/config.py         | 4 ++++
 esphome/core/entity_helpers.py | 6 +++---
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/esphome/config_validation.py b/esphome/config_validation.py
index df03f245ef5..1eac53e9b20 100644
--- a/esphome/config_validation.py
+++ b/esphome/config_validation.py
@@ -398,11 +398,6 @@ def string_strict(value):
     )
 
 
-# Max device class string length (47 chars + null = 48-byte PROGMEM buffer)
-# Keep in sync with MAX_DEVICE_CLASS_LENGTH in esphome/core/entity_base.h
-DEVICE_CLASS_MAX_LENGTH = 47
-
-
 def icon(value):
     """Validate that a given config value is a valid icon."""
     from esphome.core.config import ICON_MAX_LENGTH
diff --git a/esphome/core/config.py b/esphome/core/config.py
index cde2d280a49..21f0684e199 100644
--- a/esphome/core/config.py
+++ b/esphome/core/config.py
@@ -188,6 +188,10 @@ else:
 # Keep in sync with ESPHOME_FRIENDLY_NAME_MAX_LEN in esphome/core/entity_base.h
 FRIENDLY_NAME_MAX_LEN = 120
 
+# Max device class string length (47 chars + null = 48-byte PROGMEM buffer)
+# Keep in sync with MAX_DEVICE_CLASS_LENGTH in esphome/core/entity_base.h
+DEVICE_CLASS_MAX_LENGTH = 47
+
 # Max icon string length (63 chars + null = 64-byte PROGMEM buffer)
 # Keep in sync with MAX_ICON_LENGTH in esphome/core/entity_base.h
 ICON_MAX_LENGTH = 63
diff --git a/esphome/core/entity_helpers.py b/esphome/core/entity_helpers.py
index 70c5fff0bc1..a46d2466fdf 100644
--- a/esphome/core/entity_helpers.py
+++ b/esphome/core/entity_helpers.py
@@ -17,7 +17,7 @@ from esphome.const import (
     CONF_UNIT_OF_MEASUREMENT,
 )
 from esphome.core import CORE, ID, CoroPriority, coroutine_with_priority
-from esphome.core.config import ICON_MAX_LENGTH
+from esphome.core.config import DEVICE_CLASS_MAX_LENGTH, ICON_MAX_LENGTH
 from esphome.cpp_generator import MockObj, RawStatement, add, get_variable
 import esphome.final_validate as fv
 from esphome.helpers import cpp_string_escape, fnv1_hash_object_id, sanitize, snake_case
@@ -179,9 +179,9 @@ def _register_string(
 
 def register_device_class(value: str) -> int:
     """Register a device_class string and return its 1-based index."""
-    if value and len(value) > cv.DEVICE_CLASS_MAX_LENGTH:
+    if value and len(value) > DEVICE_CLASS_MAX_LENGTH:
         raise ValueError(
-            f"Device class string too long ({len(value)} chars, max {cv.DEVICE_CLASS_MAX_LENGTH}): '{value}'"
+            f"Device class string too long ({len(value)} chars, max {DEVICE_CLASS_MAX_LENGTH}): '{value}'"
         )
     return _register_string(
         value, _get_pool().device_classes, _MAX_DEVICE_CLASSES, "device_class"