From f48c8a64443e56e06f90271cbfd8d0e67116093d Mon Sep 17 00:00:00 2001
From: Jonathan Swoboda <154711427+swoboda1337@users.noreply.github.com>
Date: Sun, 15 Feb 2026 12:11:36 -0500
Subject: [PATCH] [combination] Fix 'coeffecient' typo with backward-compatible
 deprecation (#14004)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../components/combination/combination.cpp    |  2 +-
 esphome/components/combination/sensor.py      | 46 +++++++++++++++----
 tests/components/combination/common.yaml      |  4 +-
 3 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/esphome/components/combination/combination.cpp b/esphome/components/combination/combination.cpp
index 716d270390..ece7cca482 100644
--- a/esphome/components/combination/combination.cpp
+++ b/esphome/components/combination/combination.cpp
@@ -126,7 +126,7 @@ void LinearCombinationComponent::setup() {
 }
 
 void LinearCombinationComponent::handle_new_value(float value) {
-  // Multiplies each sensor state by a configured coeffecient and then sums
+  // Multiplies each sensor state by a configured coefficient and then sums
 
   if (!std::isfinite(value))
     return;
diff --git a/esphome/components/combination/sensor.py b/esphome/components/combination/sensor.py
index f5255fec03..0204162e8d 100644
--- a/esphome/components/combination/sensor.py
+++ b/esphome/components/combination/sensor.py
@@ -1,3 +1,5 @@
+import logging
+
 import esphome.codegen as cg
 from esphome.components import sensor
 import esphome.config_validation as cv
@@ -15,6 +17,8 @@ from esphome.const import (
 )
 from esphome.core.entity_helpers import inherit_property_from
 
+_LOGGER = logging.getLogger(__name__)
+
 CODEOWNERS = ["@Cat-Ion", "@kahrendt"]
 
 combination_ns = cg.esphome_ns.namespace("combination")
@@ -47,7 +51,8 @@ SumCombinationComponent = combination_ns.class_(
     "SumCombinationComponent", cg.Component, sensor.Sensor
 )
 
-CONF_COEFFECIENT = "coeffecient"
+CONF_COEFFICIENT = "coefficient"
+CONF_COEFFECIENT = "coeffecient"  # Deprecated, remove before 2026.12.0
 CONF_ERROR = "error"
 CONF_KALMAN = "kalman"
 CONF_LINEAR = "linear"
@@ -68,11 +73,34 @@ KALMAN_SOURCE_SCHEMA = cv.Schema(
     }
 )
 
-LINEAR_SOURCE_SCHEMA = cv.Schema(
-    {
-        cv.Required(CONF_SOURCE): cv.use_id(sensor.Sensor),
-        cv.Required(CONF_COEFFECIENT): cv.templatable(cv.float_),
-    }
+
+def _migrate_coeffecient(config):
+    """Migrate deprecated 'coeffecient' spelling to 'coefficient'."""
+    if CONF_COEFFECIENT in config:
+        if CONF_COEFFICIENT in config:
+            raise cv.Invalid(
+                f"Cannot specify both '{CONF_COEFFICIENT}' and '{CONF_COEFFECIENT}'"
+            )
+        _LOGGER.warning(
+            "'%s' is deprecated, use '%s' instead. Will be removed in 2026.12.0",
+            CONF_COEFFECIENT,
+            CONF_COEFFICIENT,
+        )
+        config[CONF_COEFFICIENT] = config.pop(CONF_COEFFECIENT)
+    elif CONF_COEFFICIENT not in config:
+        raise cv.Invalid(f"'{CONF_COEFFICIENT}' is a required option")
+    return config
+
+
+LINEAR_SOURCE_SCHEMA = cv.All(
+    cv.Schema(
+        {
+            cv.Required(CONF_SOURCE): cv.use_id(sensor.Sensor),
+            cv.Optional(CONF_COEFFICIENT): cv.templatable(cv.float_),
+            cv.Optional(CONF_COEFFECIENT): cv.templatable(cv.float_),
+        }
+    ),
+    _migrate_coeffecient,
 )
 
 SENSOR_ONLY_SOURCE_SCHEMA = cv.Schema(
@@ -162,12 +190,12 @@ async def to_code(config):
             )
             cg.add(var.add_source(source, error))
         elif config[CONF_TYPE] == CONF_LINEAR:
-            coeffecient = await cg.templatable(
-                source_conf[CONF_COEFFECIENT],
+            coefficient = await cg.templatable(
+                source_conf[CONF_COEFFICIENT],
                 [(float, "x")],
                 cg.float_,
             )
-            cg.add(var.add_source(source, coeffecient))
+            cg.add(var.add_source(source, coefficient))
         else:
             cg.add(var.add_source(source))
 
diff --git a/tests/components/combination/common.yaml b/tests/components/combination/common.yaml
index 0e5d512d08..5d46419399 100644
--- a/tests/components/combination/common.yaml
+++ b/tests/components/combination/common.yaml
@@ -27,9 +27,9 @@ sensor:
     name: Linearly combined temperatures
     sources:
       - source: template_temperature1
-        coeffecient: !lambda "return 0.4 + std::abs(x - 25) * 0.023;"
+        coefficient: !lambda "return 0.4 + std::abs(x - 25) * 0.023;"
       - source: template_temperature2
-        coeffecient: 1.5
+        coefficient: 1.5
   - platform: combination
     type: max
     name: Max of combined temperatures