diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..d3a9edc
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,70 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build & Upload
+
+This is a single-file Arduino sketch (`Gaugecontroller.ino`). Requires the **FastLED** library (`arduino-cli lib install FastLED`). Use the Arduino IDE or `arduino-cli`:
+
+```bash
+# Compile (replace board/port as needed)
+arduino-cli compile --fqbn arduino:avr:mega Gaugecontroller.ino
+
+# Upload
+arduino-cli upload -p /dev/ttyACM0 --fqbn arduino:avr:mega Gaugecontroller.ino
+```
+
+Serial monitor: 115200 baud (`Serial` is both CMD_PORT and DEBUG_PORT).
+
+## Architecture
+
+The sketch controls `GAUGE_COUNT` stepper-motor gauges using a trapezoidal velocity profile and a simple text serial protocol.
+
+### Key data structures
+
+- `GaugePins` — hardware pin mapping per gauge (dir, step, enable, active-high/low polarity flags, `ledCount`). Declared `constexpr` so `TOTAL_LEDS` can be computed from it at compile time. Configured in the `gaugePins[]` array at the top.
+- `Gauge` — per-gauge runtime state: position, target, velocity, accel, homing state machine, sweep mode.
+
+### Motion control (`updateGauge`)
+
+Each call to `updateGauge(id)` in `loop()` computes `dt` since last call and updates velocity using a braking-distance check to produce smooth trapezoidal motion. Steps are accumulated as floating-point and emitted via `doStep` when the accumulator crosses ±1.
+
+### Homing sequence (`updateHoming`)
+
+State machine: `HS_START → HS_BACKING → HS_SETTLE → HS_DONE → HS_IDLE`.  
+Backs up `homingBackoffSteps` at `homingSpeed`, waits 100 ms settle, then declares `currentPos = 0`. No physical end-stop is used; homing is purely time/step-count based.
+
+### Sweep mode
+
+When `sweepEnabled`, `updateSweepTarget` bounces `targetPos` between `minPos` and `maxPos` autonomously.
+
+### LED strip
+
+One shared WS2812B strip is driven from `LED_DATA_PIN` (default 6). Each gauge owns a contiguous segment of the strip; `gaugePins[i].ledCount` sets the segment length (0 = no LEDs). `TOTAL_LEDS` is computed at compile time via `constexpr sumLedCounts()` — no manual constant to keep in sync. Per-gauge offsets into the flat `leds[]` array are computed once in `setup()` into `gaugeLedOffset[]`. `FastLED.show()` is called immediately after each `LED` command.
+
+### Serial command protocol
+
+Commands arrive as newline-terminated ASCII lines. Each `parse*` function in `processLine` handles one command family:
+
+| Command | Syntax | Effect |
+|---|---|---|
+| `SET` | `SET <id> <pos>` | Move gauge to absolute step position |
+| `SPEED` | `SPEED <id> <steps/s>` | Set max speed |
+| `ACCEL` | `ACCEL <id> <steps/s²>` | Set acceleration |
+| `ENABLE` | `ENABLE <id> <0\|1>` | Enable/disable driver output |
+| `ZERO` | `ZERO <id>` | Mark current position as home without moving |
+| `HOME` | `HOME <id>` / `HOMEALL` | Run homing sequence |
+| `SWEEP` | `SWEEP <id> <accel> <speed>` | Start sweep (0/0 stops) |
+| `POS?` | `POS?` | Query all gauges: `POS <id> <cur> <tgt> <homed> <homingState> <sweep>` |
+| `LED` | `LED <id> <idx> <r> <g> <b>` | Set one LED (0-based index within gauge segment) to RGB colour (0–255 each) |
+| `LED?` | `LED?` | Query all LEDs: one `LED <id> <idx> <r> <g> <b>` line per LED, then `OK` |
+| `PING` | `PING` | Responds `PONG` |
+
+All commands reply `OK` or `ERR BAD_ID` / `ERR BAD_CMD` etc.
+
+### Adding gauges
+
+1. Increment `GAUGE_COUNT`.
+2. Add a `constexpr GaugePins` entry to `gaugePins[]` (including `ledCount`).
+3. Tune `maxPos` and `homingBackoffSteps` in the corresponding `Gauge` default or at runtime.
+4. `TOTAL_LEDS` and `gaugeLedOffset[]` update automatically — no manual changes needed.
diff --git a/Gaugecontroller/Gaugecontroller.ino b/Gaugecontroller/Gaugecontroller.ino
index abece38..55b6407 100644
--- a/Gaugecontroller/Gaugecontroller.ino
+++ b/Gaugecontroller/Gaugecontroller.ino
@@ -1,8 +1,14 @@
 #include <Arduino.h>
 #include <math.h>
+#include <FastLED.h>
 
 static const uint8_t GAUGE_COUNT = 2;
 
+// LED strip — one shared WS2812B strip, segmented per gauge.
+// Set LED_DATA_PIN to the digital pin driving the strip data line.
+// TOTAL_LEDS is computed automatically from gaugePins[].ledCount.
+static const uint8_t LED_DATA_PIN = 22;
+
 // For now: commands come over USB serial
 #define CMD_PORT Serial
 #define DEBUG_PORT Serial
@@ -14,14 +20,20 @@ struct GaugePins {
   bool dirInverted;
   bool stepActiveHigh;
   bool enableActiveLow;
+  uint8_t ledCount;          // WS2812B LEDs on this gauge's strip segment (0 if none)
 };
 
-GaugePins gaugePins[GAUGE_COUNT] = {
-  // dir, step, en, dirInv, stepHigh, enActiveLow
-  {50, 51, -1, false, true, true},   // Gauge 0
-  {8, 9, -1, true, true, true},   // Gauge 1
+constexpr GaugePins gaugePins[GAUGE_COUNT] = {
+  // dir, step, en, dirInv, stepHigh, enActiveLow, leds
+  {50, 51, -1, false, true, true, 6},   // Gauge 0
+  {8,  9,  -1, true,  true, true, 6},   // Gauge 1
 };
 
+constexpr uint8_t sumLedCounts(uint8_t i = 0) {
+  return i >= GAUGE_COUNT ? 0 : gaugePins[i].ledCount + sumLedCounts(i + 1);
+}
+static const uint8_t TOTAL_LEDS = sumLedCounts();
+
 enum HomingState : uint8_t {
   HS_IDLE,
   HS_START,
@@ -39,8 +51,8 @@ struct Gauge {
   long homingBackoffSteps = 3700; // should exceed reverse travel slightly
 
   float velocity = 0.0f;
-  float maxSpeed = 8000.0f;
-  float accel = 9000.0f;
+  float maxSpeed = 5000.0f;
+  float accel = 6000.0f;
   float homingSpeed = 500.0f;
 
   float stepAccumulator = 0.0f;
@@ -61,6 +73,9 @@ struct Gauge {
 Gauge gauges[GAUGE_COUNT];
 String rxLine;
 
+CRGB leds[TOTAL_LEDS];
+uint8_t gaugeLedOffset[GAUGE_COUNT];
+
 void sendReply(const String& s) {
   CMD_PORT.println(s);
 }
@@ -481,6 +496,44 @@ bool parsePing(const String& line) {
   return false;
 }
 
+bool parseLedQuery(const String& line) {
+  if (line == "LED?") {
+    for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+      for (uint8_t j = 0; j < gaugePins[i].ledCount; j++) {
+        const CRGB& c = leds[gaugeLedOffset[i] + j];
+        CMD_PORT.print("LED ");
+        CMD_PORT.print(i);
+        CMD_PORT.print(' ');
+        CMD_PORT.print(j);
+        CMD_PORT.print(' ');
+        CMD_PORT.print(c.r);
+        CMD_PORT.print(' ');
+        CMD_PORT.print(c.g);
+        CMD_PORT.print(' ');
+        CMD_PORT.println(c.b);
+      }
+    }
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+
+bool parseLed(const String& line) {
+  int id, idx, r, g, b;
+  if (sscanf(line.c_str(), "LED %d %d %d %d %d", &id, &idx, &r, &g, &b) == 5) {
+    if (id < 0 || id >= GAUGE_COUNT) { sendReply("ERR BAD_ID"); return true; }
+    if (idx < 0 || idx >= gaugePins[id].ledCount) { sendReply("ERR BAD_IDX"); return true; }
+    leds[gaugeLedOffset[id] + idx] = CRGB(constrain(r, 0, 255),
+                                          constrain(g, 0, 255),
+                                          constrain(b, 0, 255));
+    FastLED.show();
+    sendReply("OK");
+    return true;
+  }
+  return false;
+}
+
 void processLine(const String& line) {
   if (parseSet(line)) return;
   if (parseSpeed(line)) return;
@@ -490,6 +543,8 @@ void processLine(const String& line) {
   if (parseHome(line)) return;
   if (parseSweep(line)) return;
   if (parsePosQuery(line)) return;
+  if (parseLedQuery(line)) return;
+  if (parseLed(line)) return;
   if (parsePing(line)) return;
 
   sendReply("ERR BAD_CMD");
@@ -534,6 +589,16 @@ void setup() {
     gauges[i].lastUpdateMicros = micros();
   }
 
+  // Compute per-gauge LED offsets and initialise the strip.
+  uint8_t ledOff = 0;
+  for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
+    gaugeLedOffset[i] = ledOff;
+    ledOff += gaugePins[i].ledCount;
+  }
+  FastLED.addLeds<WS2812B, LED_DATA_PIN, GRB>(leds, TOTAL_LEDS);
+  FastLED.setBrightness(255);
+  FastLED.show();
+
   requestHomeAll();
 
   DEBUG_PORT.println("READY");
@@ -546,4 +611,4 @@ void loop() {
   for (uint8_t i = 0; i < GAUGE_COUNT; i++) {
     updateGauge(i);
   }
-}
\ No newline at end of file
+}