diff --git a/kernel/Kconfig b/kernel/Kconfig
index 3f12d910..4f8baa9b 100644
--- a/kernel/Kconfig
+++ b/kernel/Kconfig
@@ -1,4 +1,4 @@
-# Copyright (c) 2013 The F9 Microkernel Project. All rights reserved.
+# Copyright (c) 2013,2026 The F9 Microkernel Project. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
diff --git a/mk/generic.mk b/mk/generic.mk
index 5dbff476..ec242b4d 100644
--- a/mk/generic.mk
+++ b/mk/generic.mk
@@ -50,11 +50,18 @@ OLDCONFIG := $(KCONFIG_DIR)/oldconfig.py
 SAVEDEFCONFIG := $(KCONFIG_DIR)/savedefconfig.py
 
 # Kconfiglib commands
-cmd_menuconfig = KCONFIG_CONFIG=$(CONFIG) python3 $(MENUCONFIG) $(KCONFIG)
-cmd_genconfig = KCONFIG_CONFIG=$(CONFIG) python3 $(GENCONFIG) --header-path include/autoconf.h $(KCONFIG)
-cmd_board_defconfig = KCONFIG_CONFIG=$(CONFIG) python3 $(DEFCONFIG) --kconfig $(KCONFIG) board/$*/defconfig
-cmd_oldconfig = KCONFIG_CONFIG=$(CONFIG) python3 $(OLDCONFIG) $(KCONFIG)
-cmd_savedefconfig = KCONFIG_CONFIG=$(CONFIG) python3 $(SAVEDEFCONFIG) --kconfig $(KCONFIG) --out board/$(BOARD)/defconfig
+cmd_menuconfig = KCONFIG_CONFIG=$(CONFIG) $(PYTHON) $(MENUCONFIG) $(KCONFIG)
+cmd_genconfig = KCONFIG_CONFIG=$(CONFIG) $(PYTHON) $(GENCONFIG) --header-path include/autoconf.h $(KCONFIG)
+cmd_board_defconfig = KCONFIG_CONFIG=$(CONFIG) $(PYTHON) $(DEFCONFIG) --kconfig $(KCONFIG) board/$*/defconfig
+cmd_oldconfig = KCONFIG_CONFIG=$(CONFIG) $(PYTHON) $(OLDCONFIG) $(KCONFIG)
+cmd_savedefconfig = KCONFIG_CONFIG=$(CONFIG) $(PYTHON) $(SAVEDEFCONFIG) --kconfig $(KCONFIG) --out board/$(BOARD)/defconfig
+
+# Auto-regenerate autoconf.h when .config changes
+# Error handling: Remove partial file on failure to force retry on next build
+include/autoconf.h: $(CONFIG) $(GENCONFIG)
+	@echo "  GENCONFIG include/autoconf.h (config changed)"
+	@$(cmd_genconfig) || { rm -f include/autoconf.h; \
+		echo "ERROR: Failed to generate autoconf.h"; false; }
 
 .PHONY: bare
 bare: $(out)/$(PROJECT).bin
@@ -71,16 +78,18 @@ $(out)/%.list: $(out)/%.elf
 $(out)/%.elf: $(out)/f9_nosym.elf $(symmap_obj-list)
 	$(call quiet,elf_relink,LD     )
 
-$(out)/f9_nosym.elf: $(objs)
+# Build depends on valid autoconf.h
+$(out)/f9_nosym.elf: $(objs) include/autoconf.h
 	$(call quiet,elf,LD     )
 
-$(out)/user/%.o:user/%.c
+# All compilation depends on autoconf.h being up-to-date
+$(out)/user/%.o:user/%.c include/autoconf.h
 	$(call quiet,c_to_o_user,CC     )
 
-$(out)/%.o:%.c
+$(out)/%.o:%.c include/autoconf.h
 	$(call quiet,c_to_o,CC     )
 
-$(out)/%.o:%.S
+$(out)/%.o:%.S include/autoconf.h
 	$(call quiet,c_to_o,AS     )
 
 $(build-utils): $(out)/%:%.c
diff --git a/mk/toolchain.mk b/mk/toolchain.mk
index f472dad5..7fd2231f 100644
--- a/mk/toolchain.mk
+++ b/mk/toolchain.mk
@@ -16,6 +16,9 @@ NM = $(CROSS_COMPILE)nm
 
 BUILDCC = $(HOST_COMPILE)gcc
 
+# Python interpreter for build scripts (Kconfig tools, test runners)
+PYTHON ?= python3
+
 # Misc Information
 GIT_HEAD = $(shell git rev-parse HEAD)
 MACH_TYPE = $(shell uname -m)
diff --git a/platform/Kconfig b/platform/Kconfig
index dce18bf0..70f26035 100644
--- a/platform/Kconfig
+++ b/platform/Kconfig
@@ -1,4 +1,4 @@
-# Copyright (c) 2013 The F9 Microkernel Project. All rights reserved.
+# Copyright (c) 2013-2016,2026 The F9 Microkernel Project. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
diff --git a/user/Kconfig b/user/Kconfig
index 7c5a88af..1a51b6dc 100644
--- a/user/Kconfig
+++ b/user/Kconfig
@@ -1,18 +1,63 @@
-# Copyright (c) 2015-2017 The F9 Microkernel Project. All rights reserved.
+# Copyright (c) 2015-2017,2026 The F9 Microkernel Project. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 menu "User Space"
 
-config BUILD_USER_APPS
-	bool "Build user applications for F9 microkernel"
+choice
+	prompt "User Application"
+	default USER_APP_TESTS
+	help
+	  Select which user application to build and run.
+	  Only one application can be active at a time to avoid
+	  memory contention and resource conflicts.
+
+config USER_APP_TESTS
+	bool "Test Suite (Automated Testing)"
+	help
+	  Machine-parseable test suite for automated CI/CD.
+
+	  Commands:
+	    make run-tests              - Run test suite
+	    make run-tests FAULT=mpu    - Run MPU fault test
+	    make run-tests FAULT=canary - Run stack canary test
+
+	  Test suite verifies IPC, threads, scheduler, timer, memory,
+	  and notification subsystems. Recommended for development and CI/CD.
+
+config USER_APP_PINGPONG
+	bool "Pingpong Demo"
+	help
+	  Simple IPC demonstration with two threads exchanging messages.
+	  Useful for testing basic IPC functionality and as a minimal example.
+
+config USER_APP_NONE
+	bool "No user application"
+	help
+	  Do not build any user application. Kernel-only build.
+	  Useful for kernel development and KDB debugging.
+
+endchoice
+
+# Hardware-specific test cases (requires user application)
+menu "Hardware Test Cases"
+	depends on USER_APP_TESTS || USER_APP_PINGPONG
+
+config LCD_TEST
+	bool "LCD Test Cases"
 	default n
-	---help---
-		Enable this options to will compile userspace apps
-		into f9-kernel, This may let you unable to use kdb.
+	help
+	  LCD hardware test cases for boards with LCD support.
+	  Available when user application is enabled.
 
-source "user/Kconfig.apps"
+config EXTI_INTERRUPT_TEST
+	bool "EXTI interrupt test case"
+	default n
+	depends on EXTI0_USER_IRQ && EXTI1_USER_IRQ
+	help
+	  External interrupt (EXTI) test for hardware validation.
+	  Requires EXTI0 and EXTI1 user IRQ support.
 
-source "user/Kconfig.tests"
+endmenu
 
 endmenu
diff --git a/user/Kconfig.apps b/user/Kconfig.apps
deleted file mode 100644
index c060ac14..00000000
--- a/user/Kconfig.apps
+++ /dev/null
@@ -1,12 +0,0 @@
-# Copyright (c) 2016 The F9 Microkernel Project. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-menu "Apps"
-	depends on BUILD_USER_APPS
-
-config PINGPONG
-	bool "Pingpong game"
-	default n
-
-endmenu
diff --git a/user/Kconfig.tests b/user/Kconfig.tests
deleted file mode 100644
index 08e43392..00000000
--- a/user/Kconfig.tests
+++ /dev/null
@@ -1,34 +0,0 @@
-# Copyright (c) 2016 The F9 Microkernel Project. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-menu "Test Cases"
-	depends on BUILD_USER_APPS
-
-config EXTI_INTERRUPT_TEST
-	bool "EXTI interrupt test case"
-	default n
-	depends on EXTI0_USER_IRQ && EXTI1_USER_IRQ
-
-config LCD_TEST
-	bool "LCD Test Cases"
-	default n
-
-config TESTS
-	bool "Test Suite"
-	default n
-	help
-	  Machine-parseable test suite for automated CI/CD.
-
-	  Commands:
-	    make run-tests              - Run test suite
-	    make run-tests FAULT=mpu    - Run MPU fault test
-	    make run-tests FAULT=canary - Run stack canary test
-
-	  Test suite verifies IPC, threads, timer, and KIP.
-	  Fault tests verify MPU protection and stack overflow detection.
-
-	  For reliable results, disable other user apps (L4_TEST,
-	  PINGPONG) when running tests to avoid memory contention.
-
-endmenu
diff --git a/user/apps/build.mk b/user/apps/build.mk
index dfd638e1..aaaa5058 100644
--- a/user/apps/build.mk
+++ b/user/apps/build.mk
@@ -2,22 +2,19 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-ifdef CONFIG_BUILD_USER_APPS
-
 user-apps-dirs = ""
 
-ifdef CONFIG_PINGPONG
+ifdef CONFIG_USER_APP_PINGPONG
 user-apps-dirs += \
 	pingpong
 endif
 
-ifdef CONFIG_LCD_TEST
+ifdef CONFIG_USER_APP_TESTS
 user-apps-dirs += \
-	lcd_test
+	tests
 endif
 
-ifdef CONFIG_TESTS
+ifdef CONFIG_LCD_TEST
 user-apps-dirs += \
-	tests
-endif
+	lcd_test
 endif