diff --git a/examples/companion_radio/CompanionHelpPacked.cpp b/examples/companion_radio/CompanionHelpPacked.cpp
index ee21aad31..c5e7a1f41 100644
--- a/examples/companion_radio/CompanionHelpPacked.cpp
+++ b/examples/companion_radio/CompanionHelpPacked.cpp
@@ -1,8 +1,10 @@
+// This is the only selected Companion source compiled as C++17. Include the
+// same feature/board context as MyMesh before testing board aliases: RAK3401
+// defines its RAK_4631 compatibility macro in the variant header.
+#include "MyMesh.h"
+
 #if defined(RAK_4631) && defined(COMPANION_RADIO_FULL) \
     || (defined(STM32_PLATFORM) && defined(STM32WLxx))
-// This is the only selected Companion source compiled as C++17. Include the
-// same feature/board context as MyMesh before expanding the single help source.
-#include "MyMesh.h"
 #include "CompanionHelpWriter.h"
 
 #if !defined(STM32_PLATFORM) || COMPANION_FEATURE_TEXT_TERMINAL
diff --git a/test/test_companion_help_build_policy.py b/test/test_companion_help_build_policy.py
index 33472319c..c529f8d18 100644
--- a/test/test_companion_help_build_policy.py
+++ b/test/test_companion_help_build_policy.py
@@ -2,6 +2,11 @@
 from pathlib import Path
 import copy
 import importlib.util
+import os
+import re
+import shutil
+import subprocess
+import tempfile
 import unittest
 ROOT=Path(__file__).resolve().parents[1]
 spec=importlib.util.spec_from_file_location('help_language_policy',ROOT/'scripts/nrf52_flash_trim.py');m=importlib.util.module_from_spec(spec);spec.loader.exec_module(m)
@@ -31,6 +36,45 @@ class HelpBuildPolicy(unittest.TestCase):
   self.assertEqual(result,('compiled17',node));self.assertEqual(dict(env),before)
   self.assertEqual(env.overrides['CXXFLAGS'],['-fno-exceptions','-fno-rtti','-std=gnu++17'])
   self.assertEqual(env.overrides['CCFLAGS'],['-Os','-flto']);self.assertEqual(env['CPPDEFINES'],before['CPPDEFINES'])
+ def test_producer_resolves_header_board_alias_before_feature_gate(self):
+  compiler=os.environ.get('CXX') or shutil.which('g++') or shutil.which('clang++')
+  if not compiler:
+   self.skipTest('host C++ preprocessor required')
+  directory=ROOT/'examples/companion_radio'
+  producer=(directory/'CompanionHelpPacked.cpp').read_text()
+  # RAK3401's variant header defines RAK_4631 only after Arduino/MyMesh is
+  # included. A command-line definition would hide the linker's regression.
+  board_context='''#pragma once
+#if defined(TEST_RAK3401_VARIANT)
+#define RAK_4631 1
+#endif
+#if defined(TEST_STM32WL_VARIANT)
+#define STM32WLxx 1
+#endif
+'''
+  profiles=(
+   ('rak3401_full',('NRF52_PLATFORM','TEST_RAK3401_VARIANT','COMPANION_RADIO_FULL'),True),
+   ('rak3401_usb',('NRF52_PLATFORM','TEST_RAK3401_VARIANT'),False),
+   ('other_nrf52_full',('NRF52_PLATFORM','COMPANION_RADIO_FULL'),False),
+   ('rak4631_full',('NRF52_PLATFORM','RAK_4631','COMPANION_RADIO_FULL'),True),
+   ('stm32wl_terminal',('STM32_PLATFORM','STM32WLxx','COMPANION_FEATURE_TEXT_TERMINAL=1'),True),
+   ('stm32wl_header_alias',('STM32_PLATFORM','TEST_STM32WL_VARIANT','COMPANION_FEATURE_TEXT_TERMINAL=1'),True),
+   ('stm32wl_no_terminal',('STM32_PLATFORM','STM32WLxx','COMPANION_FEATURE_TEXT_TERMINAL=0'),False),
+  )
+  with tempfile.TemporaryDirectory(prefix='companion-help-gate-') as folder:
+   work=Path(folder)
+   (work/'MyMesh.h').write_text(board_context,encoding='ascii')
+   source=work/'CompanionHelpPacked.cpp'
+   source.write_text(producer,encoding='ascii')
+   for name,defines,selected in profiles:
+    with self.subTest(profile=name):
+     result=subprocess.run([compiler,'-E','-P','-std=c++17',
+       *['-D'+value for value in defines],'-I'+str(directory),str(source)],
+       capture_output=True,text=True)
+     self.assertEqual(result.returncode,0,result.stdout+result.stderr)
+     definition=re.search(r'size_t\s+writePackedCompanionHelp\s*\([^)]*\)\s*\{',result.stdout)
+     self.assertEqual(definition is not None,selected,
+       'packed help producer and caller must see the same header-defined board aliases')
  def test_producer_uses_same_feature_context_and_single_help_source(self):
   cpp=(ROOT/'examples/companion_radio/CompanionHelpPacked.cpp').read_text();mesh=(ROOT/'examples/companion_radio/MyMesh.cpp').read_text()
   self.assertLess(cpp.index('#include "MyMesh.h"'),cpp.index('#include "CompanionHelp.inc"'))