[blog] Add breaking change blog post for action framework const ref optimization (#66)

Author: bdraco

docs/blog/.authors.yml

@@ -9,3 +9,8 @@ authors:
     description: ESPHome Maintainer
     avatar: https://github.com/kbx81.png
     url: https://github.com/kbx81
+  bdraco:
+    name: J. Nick Koston
+    description: ESPHome Maintainer
+    avatar: https://github.com/bdraco.png
+    url: https://github.com/bdraco

docs/blog/posts/2025-11-06-action-framework-const-ref.md

@@ -0,0 +1,95 @@
+---
+date: 2025-11-06
+authors:
+  - bdraco
+comments: true
+---
+
+# Action Framework Performance Optimization
+
+The core automation framework (actions, triggers, and conditions) has been optimized to use const references instead of pass-by-value for parameter passing. This reduces memory allocations by 83% in the automation execution path.
+
+This is a **breaking change** for external components with custom actions or conditions in **ESPHome 2025.11.0 and later**.
+
+## What needs to change
+
+External components must update their action/condition method signatures to use const references:
+
+```cpp
+// ❌ Before
+template<typename... Ts>
+class MyAction : public Action<Ts...> {
+  void play(Ts... x) override {
+    // ...
+  }
+};
+
+// ✅ After
+template<typename... Ts>
+class MyAction : public Action<Ts...> {
+  void play(const Ts&... x) override {  // ← Add const&
+    // ... (no other changes needed)
+  }
+};
+```
+
+## All signatures to update
+
+- `void play(Ts... x)` → `void play(const Ts&... x)`
+- `void play_complex(Ts... x)` → `void play_complex(const Ts&... x)`
+- `bool check(Ts... x)` → `bool check(const Ts&... x)`
+
+## Compilation errors
+
+External components will fail to compile with clear error messages pointing to the methods that need updating:
+
+```
+error: no declaration matches 'void MyAction::play(Ts ...)'
+note: candidate is: 'void MyAction::play(const Ts& ...)'
+```
+
+## Finding code that needs updates
+
+```bash
+# Find actions/conditions that need updating
+grep -rn "void play(Ts\.\.\. \w\+) override" your_component/
+grep -rn "void play_complex(Ts\.\.\. \w\+) override" your_component/
+grep -rn "bool check(Ts\.\.\. \w\+) override" your_component/
+```
+
+## Supporting multiple ESPHome versions
+
+If your external component needs to support both old and new ESPHome versions, you can ifdef just the signature:
+
+```cpp
+// Use version guards for just the signature
+#if ESPHOME_VERSION_CODE >= VERSION_CODE(2025, 11, 0)
+  void play(const Ts&... x) override
+#else
+  void play(Ts... x) override
+#endif
+  {
+    // Implementation (no duplication needed)
+  }
+```
+
+## Why this change
+
+Previously, the automation framework made **6 copies** of every argument as it passed through the call chain. For `std::string` arguments (like logger messages), this meant 6 heap allocations per trigger event.
+
+The change eliminates these copies, resulting in **83% fewer heap allocations** at runtime.
+
+## No logic changes required
+
+This is a purely mechanical change - you only need to update method signatures. Your implementation logic does not need to change.
+
+## Reference Pull Request
+
+- [esphome/esphome#11704](https://github.com/esphome/esphome/pull/11704)
+
+## Questions?
+
+If you have questions about migrating your external component, please ask in:
+
+- [ESPHome Discord](https://discord.gg/KhAMKrd) - #devs channel
+- [ESPHome GitHub Discussions](https://github.com/esphome/esphome/discussions)