From a6feea5415a1109f7d175c5a3b2c9429233b57c6 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 8 Nov 2025 22:19:47 -0600
Subject: [PATCH 1/2] Add additional sx126x lambda tests

---
 tests/components/sx126x/common.yaml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tests/components/sx126x/common.yaml b/tests/components/sx126x/common.yaml
index 3f540a4bae..659550cc01 100644
--- a/tests/components/sx126x/common.yaml
+++ b/tests/components/sx126x/common.yaml
@@ -26,6 +26,15 @@ sx126x:
       - lambda: |-
           ESP_LOGD("lambda", "packet %.2f %.2f %s", rssi, snr, format_hex(x).c_str());
 
+number:
+  - platform: template
+    name: "SX126x Number"
+    id: my_number
+    optimistic: true
+    min_value: 0
+    max_value: 100
+    step: 1
+
 button:
   - platform: template
     name: "SX126x Button"
@@ -37,3 +46,5 @@ button:
         - sx126x.set_mode_rx
         - sx126x.send_packet:
             data: [0xC5, 0x51, 0x78, 0x82, 0xB7, 0xF9, 0x9C, 0x5C]
+        - sx126x.send_packet: !lambda |-
+            return {0x01, 0x02, (uint8_t)id(my_number).state};

From 21d0c8b54903fdaf74f402acd25bee8d6e7795b8 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 8 Nov 2025 23:36:06 -0600
Subject: [PATCH 2/2] optimize

---
 esphome/components/sx126x/automation.h | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/esphome/components/sx126x/automation.h b/esphome/components/sx126x/automation.h
index 41f0a888e5..2282c583cb 100644
--- a/esphome/components/sx126x/automation.h
+++ b/esphome/components/sx126x/automation.h
@@ -16,33 +16,31 @@ template<typename... Ts> class SendPacketAction : public Action<Ts...>, public P
  public:
   void set_data_template(std::vector<uint8_t> (*func)(Ts...)) {
     this->data_.func = func;
-    this->static_ = false;
+    this->len_ = -1;  // Sentinel value indicates template mode
   }
 
   void set_data_static(const uint8_t *data, size_t len) {
-    this->data_.static_data.ptr = data;
-    this->data_.static_data.len = len;
-    this->static_ = true;
+    this->data_.data = data;
+    this->len_ = len;  // Length >= 0 indicates static mode
   }
 
   void play(const Ts &...x) override {
     std::vector<uint8_t> data;
-    if (this->static_) {
-      data.assign(this->data_.static_data.ptr, this->data_.static_data.ptr + this->data_.static_data.len);
+    if (this->len_ >= 0) {
+      // Static mode: copy from flash to vector
+      data.assign(this->data_.data, this->data_.data + this->len_);
     } else {
+      // Template mode: call function
       data = this->data_.func(x...);
     }
     this->parent_->transmit_packet(data);
   }
 
  protected:
-  bool static_{true};
+  ssize_t len_{-1};  // -1 = template mode, >=0 = static mode with length
   union Data {
-    std::vector<uint8_t> (*func)(Ts...);
-    struct {
-      const uint8_t *ptr;
-      size_t len;
-    } static_data;
+    std::vector<uint8_t> (*func)(Ts...);  // Function pointer (stateless lambdas)
+    const uint8_t *data;                  // Pointer to static data in flash
   } data_;
 };