diff --git a/.gitignore b/.gitignore
index 2cf8684..e669370 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,6 @@
+# Generated from version.txt
+src/version.h
+
 # PlatformIO
 .pio/
 .pioenvs/
diff --git a/platformio.ini b/platformio.ini
index 11bd9a7..b22a594 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -1,18 +1,38 @@
-[env:m5stack-atoms3r]
+[env:s3lite-server]
 platform = espressif32@6.7.0
 board = esp32-s3-devkitc-1
 framework = arduino
-board_build.arduino.memory_type = qio_opi
+board_build.arduino.memory_type = qio_qspi
 build_flags =
     -DESP32S3
-    -DBOARD_HAS_PSRAM
-    -mfix-esp32-psram-cache-issue
     -DCORE_DEBUG_LEVEL=5
     -DARDUINO_USB_CDC_ON_BOOT=1
     -DARDUINO_USB_MODE=1
-    -DCONFIG_BT_NIMBLE_ENABLED
 lib_deps =
+    fastled/FastLED@^3
     h2zero/NimBLE-Arduino@^2
 upload_port = /dev/ttyACM1
 upload_speed = 115200
-upload_flags = --no-stub
\ No newline at end of file
+upload_flags = --no-stub
+build_src_filter = +<main.cpp> -<client.cpp>
+extra_scripts = pre:tools/pio_version_pre.py
+
+[env:s3lite-client]
+platform = espressif32@6.7.0
+board = esp32-s3-devkitc-1
+framework = arduino
+board_build.arduino.memory_type = qio_qspi
+build_flags =
+    -DESP32S3
+    -DCORE_DEBUG_LEVEL=5
+    -DARDUINO_USB_CDC_ON_BOOT=1
+    -DARDUINO_USB_MODE=1
+    -DDEVICE_ID=1
+lib_deps =
+    fastled/FastLED@^3
+    h2zero/NimBLE-Arduino@^2
+upload_port = /dev/ttyACM2
+upload_speed = 115200
+upload_flags = --no-stub
+build_src_filter = +<client.cpp> -<main.cpp>
+extra_scripts = pre:tools/pio_version_pre.py
diff --git a/tools/pio_version_pre.py b/tools/pio_version_pre.py
new file mode 100755
index 0000000..130216f
--- /dev/null
+++ b/tools/pio_version_pre.py
@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+"""Pre-build: generate src/version.h from version.txt so the firmware
+   uses the single source of truth for version numbers."""
+Import("env")
+import os
+
+project_dir = env.subst("$PROJECT_DIR")
+ver_file = os.path.join(project_dir, "version.txt")
+out_file = os.path.join(project_dir, "src", "version.h")
+
+versions = {}
+with open(ver_file) as f:
+    for line in f:
+        line = line.strip()
+        if "=" in line:
+            k, v = line.split("=", 1)
+            versions[k.strip()] = v.strip()
+
+header = f"""// Auto-generated from version.txt — DO NOT EDIT
+#define FIRMWARE_VERSION_SERVER "{versions['server']}"
+#define FIRMWARE_VERSION_CLIENT "{versions['client']}"
+"""
+
+with open(out_file, "w") as f:
+    f.write(header)
+
+print(f"  versions: server={versions['server']}  client={versions['client']}  ->  src/version.h")
diff --git a/version.txt b/version.txt
new file mode 100644
index 0000000..71ce7a5
--- /dev/null
+++ b/version.txt
@@ -0,0 +1,2 @@
+server=6
+client=1