From a73a9516c2b0d683638f368c8d60a378730d306d Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sun, 3 May 2026 16:53:10 -0500
Subject: [PATCH] [climate] Use const remove_reference_t<T> & to avoid copies
 of non-ref Ts

---
 esphome/components/climate/__init__.py  | 10 +++++++---
 esphome/components/climate/automation.h |  8 +++++---
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/esphome/components/climate/__init__.py b/esphome/components/climate/__init__.py
index a55c5b0f5a..9d228e0b72 100644
--- a/esphome/components/climate/__init__.py
+++ b/esphome/components/climate/__init__.py
@@ -526,11 +526,15 @@ async def climate_control_to_code(config, action_id, template_arg, args):
         else:
             body_lines.append(f"call.{setter}({cg.safe_exp(value)});")
 
-    # Match ControlAction::ApplyFn signature: trigger args forwarded
-    # by-value as Ts...
+    # Match ControlAction::ApplyFn signature: `const std::remove_reference_t<T> &`
+    # for each trigger arg so non-reference Ts stay no-copy (`const T &`) and
+    # reference Ts collapse correctly without producing `const T & &`.
     apply_args = [
         (ClimateCall.operator("ref"), "call"),
-        *args,
+        *(
+            (cg.RawExpression(f"const std::remove_reference_t<{cg.safe_exp(t)}> &"), n)
+            for t, n in args
+        ),
     ]
     apply_lambda = LambdaExpression(
         ["\n".join(body_lines)],
diff --git a/esphome/components/climate/automation.h b/esphome/components/climate/automation.h
index c556206926..76784f67a0 100644
--- a/esphome/components/climate/automation.h
+++ b/esphome/components/climate/automation.h
@@ -11,11 +11,13 @@ namespace esphome::climate {
 // Trigger args are forwarded to the apply function so user lambdas
 // (e.g. `target_temperature: !lambda "return x;"`) keep working.
 //
-// Ts... must be forwarded by-value: `const T &` is ill-formed when T is
-// already a reference type (some triggers pass `std::string &`).
+// Trigger args are forwarded as `const std::remove_reference_t<Ts> &...`
+// (instead of `const Ts &...`) so codegen can emit the same form in the
+// apply lambda's parameter list without producing `const T & &` for
+// triggers whose Ts already carries a reference (e.g. `std::string &`).
 template<typename... Ts> class ControlAction : public Action<Ts...> {
  public:
-  using ApplyFn = void (*)(ClimateCall &, Ts...);
+  using ApplyFn = void (*)(ClimateCall &, const std::remove_reference_t<Ts> &...);
   ControlAction(Climate *climate, ApplyFn apply) : climate_(climate), apply_(apply) {}
 
   void play(const Ts &...x) override {