From 1ee478c41978d342b36d8b1c6935fe0ba6e3191e Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Thu, 19 Mar 2026 10:19:19 -1000
Subject: [PATCH] [logger] Fix ESP8266 crash with VERY_VERBOSE log level

Move logger codegen priority above platform init so that
global_logger is set before setup_preferences() or any other
platform code that may contain ESP_LOG* calls.

Previously the logger initialized at DIAGNOSTICS priority (90),
which ran after PLATFORM (1000). With VERY_VERBOSE, the
ESP_LOGVV in ESP8266Preferences::setup() fired before
global_logger was set, causing a nullptr dereference crash.

Also hardcode `using namespace esphome;` in writer.py so it
precedes all variable declarations regardless of codegen
priority ordering.

Fixes #14970
---
 esphome/components/logger/__init__.py |  7 ++++---
 esphome/core/config.py                |  4 +++-
 esphome/coroutine.py                  | 10 ++++++++--
 esphome/writer.py                     |  3 +++
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/esphome/components/logger/__init__.py b/esphome/components/logger/__init__.py
index 675f9a2ca4..54629465da 100644
--- a/esphome/components/logger/__init__.py
+++ b/esphome/components/logger/__init__.py
@@ -56,6 +56,7 @@ from esphome.const import (
     PlatformFramework,
 )
 from esphome.core import CORE, CoroPriority, Lambda, coroutine_with_priority
+from esphome.types import ConfigType
 
 CODEOWNERS = ["@esphome/core"]
 logger_ns = cg.esphome_ns.namespace("logger")
@@ -323,9 +324,9 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-@coroutine_with_priority(CoroPriority.DIAGNOSTICS)
-async def to_code(config):
-    baud_rate = config[CONF_BAUD_RATE]
+@coroutine_with_priority(CoroPriority.LOGGER_INIT)
+async def to_code(config: ConfigType) -> None:
+    baud_rate: int = config[CONF_BAUD_RATE]
     level = config[CONF_LEVEL]
     CORE.data.setdefault(CONF_LOGGER, {})[CONF_LEVEL] = level
     initial_level = LOG_LEVELS[config.get(CONF_INITIAL_LEVEL, level)]
diff --git a/esphome/core/config.py b/esphome/core/config.py
index e112720f2b..e02c6ec75f 100644
--- a/esphome/core/config.py
+++ b/esphome/core/config.py
@@ -587,7 +587,9 @@ async def _add_looping_components() -> None:
 
 @coroutine_with_priority(CoroPriority.CORE)
 async def to_code(config: ConfigType) -> None:
-    cg.add_global(cg.global_ns.namespace("esphome").using)
+    # using namespace esphome is hardcoded in writer.py to guarantee it
+    # precedes all variable declarations regardless of coroutine priority.
+
     # These can be used by user lambdas, put them to default scope
     # picolibc (IDF 6.0+) declares isnan in global scope, conflicting with using std::isnan
     cg.add_global(cg.RawStatement("#ifndef __PICOLIBC__"))
diff --git a/esphome/coroutine.py b/esphome/coroutine.py
index f5d512e510..e6632d0c01 100644
--- a/esphome/coroutine.py
+++ b/esphome/coroutine.py
@@ -63,7 +63,13 @@ class CoroPriority(enum.IntEnum):
     resolution during code generation.
     """
 
-    # Platform initialization - must run first
+    # Logger early init - must run before all other code because:
+    # 1. All code assumes global_logger is ready for ESP_LOG* calls
+    # 2. Without this, any log call before logger init dereferences nullptr
+    # Examples: logger (1100)
+    LOGGER_INIT = 1100
+
+    # Platform initialization
     # Examples: esp32, esp8266, rp2040
     PLATFORM = 1000
 
@@ -83,7 +89,7 @@ class CoroPriority(enum.IntEnum):
     CORE = 100
 
     # Diagnostic and debugging systems
-    # Examples: logger (90)
+    # Examples: debug component (90)
     DIAGNOSTICS = 90
 
     # Status and monitoring systems
diff --git a/esphome/writer.py b/esphome/writer.py
index fd4c811fb3..69a35d00e3 100644
--- a/esphome/writer.py
+++ b/esphome/writer.py
@@ -381,7 +381,10 @@ def write_cpp(code_s):
         code_format = CPP_BASE_FORMAT
 
     copy_src_tree()
+    # using namespace esphome must precede all variable declarations since
+    # codegen types assume this namespace is in scope (esphome_ns = global_ns).
     global_s = '#include "esphome.h"\n'
+    global_s += "using namespace esphome;\n"
     global_s += CORE.cpp_global_section
 
     full_file = f"{code_format[0] + CPP_INCLUDE_BEGIN}\n{global_s}{CPP_INCLUDE_END}"