From 98aad834077f5938d75fae35d9d4189280323be8 Mon Sep 17 00:00:00 2001
From: clydebarrow <2366188+clydebarrow@users.noreply.github.com>
Date: Mon, 19 Oct 2026 09:01:09 +1100
Subject: [PATCH] [packet_interface] Check the layers in the link schema

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../components/packet_interface/__init__.py   | 35 +++++++++----------
 tests/unit_tests/test_packet_interface.py     | 12 ++-----
 2 files changed, 19 insertions(+), 28 deletions(-)

diff --git a/esphome/components/packet_interface/__init__.py b/esphome/components/packet_interface/__init__.py
index 362deb51126..ac51b7eb47a 100644
--- a/esphome/components/packet_interface/__init__.py
+++ b/esphome/components/packet_interface/__init__.py
@@ -54,16 +54,9 @@ def AUTO_LOAD(config: list[ConfigType] | None = None) -> list[str]:
     return sorted(loads)
 
 
-def _final_validate(config: list[ConfigType]) -> None:
-    for index, interface in enumerate(config):
-        try:
-            check_session(interface)
-        except cv.Invalid as err:
-            err.prepend([index])
-            raise
-
-
-FINAL_VALIDATE_SCHEMA = _final_validate
+def _validate_layers(config: ConfigType) -> ConfigType:
+    check_session(config)
+    return config
 
 
 def packet_interface_schema(
@@ -72,15 +65,19 @@ def packet_interface_schema(
     max_packet_size_limit: int = 4096,
 ) -> cv.Schema:
     """Schema for a link platform, with the layers that can be stacked on it."""
-    return cv.Schema(
-        {
-            cv.GenerateID(): cv.declare_id(class_),
-            cv.Optional(
-                CONF_MAX_PACKET_SIZE, default=default_max_packet_size
-            ): cv.int_range(16, max_packet_size_limit),
-            **LINK_LAYER_SCHEMAS,
-        }
-    ).extend(cv.COMPONENT_SCHEMA)
+    return (
+        cv.Schema(
+            {
+                cv.GenerateID(): cv.declare_id(class_),
+                cv.Optional(
+                    CONF_MAX_PACKET_SIZE, default=default_max_packet_size
+                ): cv.int_range(16, max_packet_size_limit),
+                **LINK_LAYER_SCHEMAS,
+            }
+        )
+        .extend(cv.COMPONENT_SCHEMA)
+        .add_extra(_validate_layers)
+    )
 
 
 async def new_packet_interface(config: ConfigType, *args: Any) -> MockObj:
diff --git a/tests/unit_tests/test_packet_interface.py b/tests/unit_tests/test_packet_interface.py
index 16a203c38a5..f7fc8d4b5a2 100644
--- a/tests/unit_tests/test_packet_interface.py
+++ b/tests/unit_tests/test_packet_interface.py
@@ -166,15 +166,9 @@ def test_rolling_code_requires_session(setup_core) -> None:
     """The rolling code needs the session's keep-alives, so the peer sends this device's boot number back."""
     rolling = {CONF_ENCRYPTION: {"key": "secret", "rolling_code_enable": True}}
     with pytest.raises(cv.Invalid, match="session"):
-        packet_interface.FINAL_VALIDATE_SCHEMA(
-            [uart_packet_interface.CONFIG_SCHEMA(rolling)]
-        )
-    packet_interface.FINAL_VALIDATE_SCHEMA(
-        [
-            uart_packet_interface.CONFIG_SCHEMA({**rolling, CONF_SESSION: None}),
-            uart_packet_interface.CONFIG_SCHEMA({CONF_ENCRYPTION: "secret"}),
-        ]
-    )
+        uart_packet_interface.CONFIG_SCHEMA(rolling)
+    uart_packet_interface.CONFIG_SCHEMA({**rolling, CONF_SESSION: None})
+    uart_packet_interface.CONFIG_SCHEMA({CONF_ENCRYPTION: "secret"})
 
 
 @pytest.mark.parametrize(