ui: changed whiskey mark looks

- WhiskeyMark widget shows roll/pitch as horizon line
- ArduinoData model includes IMU euler angles
- startup waits for Arduino via /health endpoint
- config_service exposes backendUrl

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -65,6 +65,8 @@ scripts/*.pyo
 *.pyc
 *.pyo
 __pycache__/
+.venv/
+uv.lock
 
 
 # extra resources

arduino/.gitignore

@@ -0,0 +1,3 @@
+# arduino test files
+
+test/

arduino/IMU.md

@@ -0,0 +1,81 @@
+# WT61 IMU Quick Reference
+
+6-axis IMU (accelerometer + gyroscope) with onboard angle calculation via Kalman filter.
+
+## Serial Configuration
+
+| Setting | Factory Default | Our Config |
+|---------|-----------------|------------|
+| Baud rate | 115200 | 115200 |
+| Output rate | 100Hz | 100Hz |
+
+**Config commands** (sent on init):
+```
+0xFF 0xAA 0x66  # Vertical mounting mode
+0xFF 0xAA 0x63  # 115200 baud / 100Hz
+```
+Settings are saved to flash - persist across power cycles.
+
+**Fallback to 9600/20Hz:** If 115200 causes packet loss on AltSoftSerial, change `0x63` to `0x64` in `imu.cpp` and add `imuSerial.begin(9600)` after the delay.
+
+## Wiring (ATmega328P / AltSoftSerial)
+
+| WT61 Pin | Arduino Pin | Notes |
+|----------|-------------|-------|
+| TX | 8 (RX) | AltSoftSerial fixed pin |
+| RX | 9 (TX) | Only needed for config commands |
+| VCC | 5V | |
+| GND | GND | |
+
+## Packet Structure
+
+11 bytes per packet, continuous stream (3 packet types interleaved):
+
+```
+Byte 0:    0x55 (header)
+Byte 1:    Packet type
+Bytes 2-3: Value 0 (int16_t, little-endian)
+Bytes 4-5: Value 1
+Bytes 6-7: Value 2
+Bytes 8-9: Temperature (usually ignored)
+Byte 10:   Checksum (sum of bytes 0-9, lower 8 bits)
+```
+
+### Packet Types
+
+| Type | Byte 1 | V0 | V1 | V2 |
+|------|--------|----|----|-----|
+| Acceleration | 0x51 | ax | ay | az |
+| Gyroscope | 0x52 | gx | gy | gz |
+| Angle | 0x53 | roll | pitch | yaw |
+
+## Scale Factors
+
+| Measurement | Formula | Range |
+|-------------|---------|-------|
+| Acceleration | `raw / 32768.0 * 16.0` | +/-16g |
+| Gyroscope | `raw / 32768.0 * 2000.0` | +/-2000 deg/s |
+| Angle | `raw / 32768.0 * 180.0` | +/-180 deg |
+| Temperature | `raw / 340.0 + 36.25` | Celsius |
+
+## Known Quirks
+
+- **Boot time**: Module needs ~200-500ms after power-on before sending valid data
+- **Config at wrong baud**: Commands sent at wrong baud rate are ignored (garbled bytes) - this is actually useful for idempotent config-on-boot
+- **AltSoftSerial at 115200**: Technically out of spec for 16MHz AVR, but TX-only bursts of a few bytes work fine. Don't try sustained RX at that rate.
+
+## Commands
+
+All commands are 3 bytes: `0xFF 0xAA <data>`
+
+| Data Byte | Function | Notes |
+|-----------|----------|-------|
+| 0x52 | Zero Z-axis angle | Resets yaw to 0 |
+| 0x67 | Accelerometer calibration | Keep module level, zeros X/Y |
+| 0x60 | Toggle sleep mode | Toggles between standby and active |
+| 0x61 | Serial mode | Enable UART, disable I2C |
+| 0x62 | I2C mode | Enable I2C, disable UART |
+| 0x63 | 115200 baud / 100Hz | Factory default |
+| 0x64 | 9600 baud / 20Hz | Our config |
+| 0x65 | Horizontal mounting | Module placed flat |
+| 0x66 | Vertical mounting | Module placed upright |

arduino/PROTOCOL.md

@@ -0,0 +1,56 @@
+# Arduino-Pi Communication Protocol
+
+Telemetry protocol for Arduino → Pi communication over UART at 115200 baud.
+
+## Design Rationale
+
+- **ASCII-based**: Human-debuggable, digits are self-bounding (no accidental header spoofing)
+- **TSV format**: Tab delimiter, predictable field count, trivial to parse, survives floating decimals
+- **Null-terminated**: `\0` (0x00) is unambiguous end-of-line, avoids CRLF headaches
+- **10Hz rate**: ~50 bytes/line × 10Hz = 500 B/s, well under 115200 baud capacity (~4% utilization)
+
+## Telemetry Frame (Arduino → Pi)
+
+```
+field0\tfield1\tfield2\t...\tfieldN\0
+```
+
+### Fields
+
+| Index | Name   | Unit    | Description                    |
+|-------|--------|---------|--------------------------------|
+| 0     | V_bat  | V       | Battery voltage                |
+| 1     | Ax     | g       | Acceleration X                 |
+| 2     | Ay     | g       | Acceleration Y                 |
+| 3     | Az     | g       | Acceleration Z                 |
+| 4     | Gx     | deg/s   | Angular velocity X             |
+| 5     | Gy     | deg/s   | Angular velocity Y             |
+| 6     | Gz     | deg/s   | Angular velocity Z             |
+| 7     | Roll   | deg     | Euler angle roll               |
+| 8     | Pitch  | deg     | Euler angle pitch              |
+| 9     | Yaw    | deg     | Euler angle yaw                |
+| 10    | RPM    | RPM     | Engine RPM                     |
+| 11    | Gear   | -       | Gear position (0=N, 1-6)       |
+
+### Example
+
+```
+12.45\t0.02\t-0.01\t1.00\t0.50\t-0.25\t0.10\t2.35\t-1.20\t45.80\t3500\t3\0
+```
+
+## Stale Data Handling
+
+When IMU data is stale, empty fields are sent to preserve field count:
+```
+12.45\t\t\t\t\t\t\t\t\t\0
+```
+Backend parses empty fields as null/NaN.
+
+## Commands (Pi → Arduino)
+
+TBD: Command structure for configuration, calibration triggers, etc.
+
+## Versioning
+
+Protocol changes should bump a version field or use a different frame header.
+Currently unversioned (v0 / development).

arduino/README.md

@@ -11,26 +11,45 @@ Sensor interface running on Arduino Nano, communicating with Pi via UART.
 ## Current Capabilities
 
 - Battery voltage monitoring (voltage divider on A0)
-- Serial output at 9600 baud, 1Hz update rate
+- WT61 IMU/gyro via AltSoftSerial (9-axis: accel, gyro, euler angles)
+- Duplex UART to Pi at 115200 baud, 10Hz telemetry output
+- Simple text-based protocol for easy debugging
 
-## Planned
+## Dependencies
 
-- RPM sensing (pulse counting from ignition coil)
-- Engine temperature (thermocouple/NTC)
-- Gear position indicator
-- Turn signal / high beam status
+Install via Arduino Library Manager:
+- **AltSoftSerial** by Paul Stoffregen - for WT61 IMU serial
+
+## Pin Assignments
+
+| Pin | Function |
+|-----|----------|
+| A0 | Battery voltage (via divider) |
+| D0 (RX) | Pi UART RX ← Arduino TX |
+| D1 (TX) | Pi UART TX → Arduino RX |
+| D8 | WT61 IMU RX (AltSoftSerial) |
+| D9 | WT61 IMU TX (unused, AltSoftSerial fixed pin) |
+| D13 | Status LED (heartbeat) |
 
 ## Hardware
 
 - **MCU**: Arduino Nano (ATmega328P)
-- **Connection**: UART to Pi GPIO (TX→RX, RX→TX, common GND)
-- **Voltage sensing**: Resistor divider scaled for 0-20V input range
+- **Pi Connection**: UART at 115200 baud (TX→RX, RX→TX, common GND)
+- **IMU**: WT61 module at 9600 baud, 20Hz output
+- **Voltage sensing**: Resistor divider (100k/47k) scaled for 0-20V input
 
 ## Protocol
 
-Simple text-based for now:
-```
-V_bat: 12.45V
-```
+TSV (tab-separated), null-terminated frames at 10Hz. See [PROTOCOL.md](PROTOCOL.md) for full specification.
 
-Future: structured binary or JSON for multiple sensors.
+## Planned
+
+- RPM sensing (pulse counting from ignition coil)
+- Gear position indicator  
+  
+### Not planned
+
+- Engine temperature (thermocouple/NTC)  
+  *Borderline do not want to do, simple but not really useful*
+- Turn signal / high beam status  
+  *No need to do something the dash already does* 

arduino/main/comms.cpp

@@ -0,0 +1,113 @@
+#include "comms.h"
+
+// Pi communication uses hardware Serial (pins 0/1)
+// Baud rate - 115200 is reasonable for duplex with Pi
+static const long BAUD_RATE = 115200;
+
+// Command buffer
+static const int CMD_BUF_SIZE = 64;
+static char cmdBuf[CMD_BUF_SIZE];
+static int cmdIndex = 0;
+static bool cmdReady = false;
+
+// Connection tracking
+static unsigned long lastRxTime = 0;
+
+void comms_init() {
+  Serial.begin(BAUD_RATE);
+  cmdIndex = 0;
+  cmdReady = false;
+}
+
+bool comms_update() {
+  while (Serial.available()) {
+    char c = Serial.read();
+    lastRxTime = millis();
+
+    if (c == '\n' || c == '\r') {
+      if (cmdIndex > 0) {
+        cmdBuf[cmdIndex] = '\0';
+        cmdReady = true;
+        cmdIndex = 0;
+        return true;
+      }
+    } else if (cmdIndex < CMD_BUF_SIZE - 1) {
+      cmdBuf[cmdIndex++] = c;
+    }
+    // else: overflow, silently drop extra chars
+  }
+  return false;
+}
+
+void comms_send_telemetry(float voltage, const ImuData& imu, bool imu_valid, int rpm, int gear) {
+  // Field 0: voltage
+  Serial.print(voltage, 2);
+  Serial.write('\t');
+
+  if (imu_valid) {
+    // Fields 1-3: acceleration
+    Serial.print(imu.ax, 2);
+    Serial.write('\t');
+    Serial.print(imu.ay, 2);
+    Serial.write('\t');
+    Serial.print(imu.az, 2);
+    Serial.write('\t');
+
+    // Fields 4-6: angular velocity
+    Serial.print(imu.gx, 2);
+    Serial.write('\t');
+    Serial.print(imu.gy, 2);
+    Serial.write('\t');
+    Serial.print(imu.gz, 2);
+    Serial.write('\t');
+
+    // Fields 7-9: euler angles
+    Serial.print(imu.roll, 2);
+    Serial.write('\t');
+    Serial.print(imu.pitch, 2);
+    Serial.write('\t');
+    Serial.print(imu.yaw, 2);
+  } else {
+    // Empty fields for stale IMU (9 tabs for 9 empty fields)
+    Serial.print(F("\t\t\t\t\t\t\t\t"));
+  }
+
+  // Fields 10-11: RPM and gear
+  Serial.write('\t');
+  Serial.print(rpm);
+  Serial.write('\t');
+  Serial.print(gear);
+
+  // Null terminator (no newline)
+  Serial.write('\0');
+}
+
+void comms_send(const char* key, float value, int decimals) {
+  Serial.print(key);
+  Serial.print(": ");
+  Serial.println(value, decimals);
+}
+
+void comms_send(const char* key, int value) {
+  Serial.print(key);
+  Serial.print(": ");
+  Serial.println(value);
+}
+
+void comms_send(const char* key, const char* value) {
+  Serial.print(key);
+  Serial.print(": ");
+  Serial.println(value);
+}
+
+const char* comms_get_command() {
+  if (cmdReady) {
+    cmdReady = false;
+    return cmdBuf;
+  }
+  return "";
+}
+
+bool comms_is_connected(unsigned long timeout_ms) {
+  return (millis() - lastRxTime) < timeout_ms;
+}

arduino/main/comms.h

@@ -0,0 +1,31 @@
+#ifndef COMMS_H
+#define COMMS_H
+
+#include <Arduino.h>
+#include "imu.h"
+
+// Initialize Pi serial communication (call in setup)
+void comms_init();
+
+// Process incoming commands from Pi - call in loop
+// Returns true if a complete command was received
+bool comms_update();
+
+// Send complete telemetry frame (TSV format, null-terminated)
+// Format: V_bat\tAx\tAy\tAz\tGx\tGy\tGz\tRoll\tPitch\tYaw\tRPM\tGear\0
+// If imu_valid is false, IMU fields are empty (but tabs preserved)
+void comms_send_telemetry(float voltage, const ImuData& imu, bool imu_valid, int rpm, int gear);
+
+// Send key:value line (for debug/ACK, newline-terminated)
+void comms_send(const char* key, float value, int decimals = 2);
+void comms_send(const char* key, int value);
+void comms_send(const char* key, const char* value);
+
+// Get last received command (empty if none)
+// Command buffer is cleared after reading
+const char* comms_get_command();
+
+// Check if connected (received any data recently)
+bool comms_is_connected(unsigned long timeout_ms = 5000);
+
+#endif

arduino/main/gear.cpp

@@ -0,0 +1,19 @@
+#include "gear.h"
+
+// Mock gear: derived from RPM bands
+// Real sensor would read position switch
+
+void gear_init() {
+  // Nothing to init for mock
+}
+
+int gear_get(int rpm) {
+  // Simulate gear based on RPM
+  // N < 1000, 1st < 2500, 2nd < 4000, 3rd < 5500, 4th < 7000, 5th+
+  if (rpm < 1000) return 0;  // Neutral
+  if (rpm < 2500) return 1;
+  if (rpm < 4000) return 2;
+  if (rpm < 5500) return 3;
+  if (rpm < 7000) return 4;
+  return 5;
+}

arduino/main/gear.h

@@ -0,0 +1,7 @@
+#ifndef GEAR_H
+#define GEAR_H
+
+void gear_init();
+int gear_get(int rpm);  // Returns gear 0-6 (0=neutral)
+
+#endif

arduino/main/imu.cpp

@@ -0,0 +1,215 @@
+#include "imu.h"
+#include <AltSoftSerial.h>
+
+// AltSoftSerial uses fixed pins on ATmega328P:
+// RX = Pin 8, TX = Pin 9
+static AltSoftSerial imuSerial;
+
+// WT61 packet structure:
+// Byte 0: 0x55 (header)
+// Byte 1: Packet type (0x51=accel, 0x52=gyro, 0x53=angle)
+// Bytes 2-9: Data (4x int16_t, little-endian)
+// Byte 10: Checksum (sum of bytes 0-9, lower 8 bits)
+static const uint8_t PACKET_HEADER = 0x55;
+static const uint8_t PACKET_ACCEL  = 0x51;
+static const uint8_t PACKET_GYRO   = 0x52;
+static const uint8_t PACKET_ANGLE  = 0x53;
+static const int PACKET_SIZE = 11;
+
+// Receive buffer
+static uint8_t rxBuf[PACKET_SIZE];
+static int rxIndex = 0;
+
+// Latest data
+static ImuData currentData = {0};
+
+// Calibration offsets and state
+static ImuData offsets = {0};
+static bool calibrated = false;
+
+// Scale factors from WT61 datasheet
+// Accel: raw / 32768 * 16g
+// Gyro:  raw / 32768 * 2000 deg/s
+// Angle: raw / 32768 * 180 deg
+static const float ACCEL_SCALE = 16.0 / 32768.0;
+static const float GYRO_SCALE  = 2000.0 / 32768.0;
+static const float ANGLE_SCALE = 180.0 / 32768.0;
+
+static int16_t parseI16(uint8_t lo, uint8_t hi) {
+  return (int16_t)((hi << 8) | lo);
+}
+
+static bool validateChecksum() {
+  uint8_t sum = 0;
+  for (int i = 0; i < PACKET_SIZE - 1; i++) {
+    sum += rxBuf[i];
+  }
+  return sum == rxBuf[PACKET_SIZE - 1];
+}
+
+static void processPacket() {
+  if (!validateChecksum()) {
+    return;  // Bad packet, ignore
+  }
+
+  uint8_t type = rxBuf[1];
+  int16_t v0 = parseI16(rxBuf[2], rxBuf[3]);
+  int16_t v1 = parseI16(rxBuf[4], rxBuf[5]);
+  int16_t v2 = parseI16(rxBuf[6], rxBuf[7]);
+  // v3 at bytes 8-9 is temperature, ignored for now
+
+  switch (type) {
+    case PACKET_ACCEL:
+      currentData.ax = v0 * ACCEL_SCALE;
+      currentData.ay = v1 * ACCEL_SCALE;
+      currentData.az = v2 * ACCEL_SCALE;
+      break;
+    case PACKET_GYRO:
+      currentData.gx = v0 * GYRO_SCALE;
+      currentData.gy = v1 * GYRO_SCALE;
+      currentData.gz = v2 * GYRO_SCALE;
+      break;
+    case PACKET_ANGLE:
+      currentData.roll  = v0 * ANGLE_SCALE;
+      currentData.pitch = v1 * ANGLE_SCALE;
+      currentData.yaw   = v2 * ANGLE_SCALE;
+      currentData.lastUpdate = millis();
+      break;
+  }
+}
+
+void imu_init() {
+  // Configure WT61 at 115200 - stays there (no baud switch)
+  // See IMU.md for command reference
+  imuSerial.begin(115200);
+
+  imu_send_cmd(0x52);  // Reset yaw (for the sake of it)
+  delay(50);
+  imu_send_cmd(0x65);  // Flat mounting mode
+  delay(50);
+  imu_send_cmd(0x64);  // 9600 bauds / 20Hz report
+  delay(150);          // Let WT61 process config
+
+  // Revert to 9600 bauds
+  imuSerial.begin(9600);
+
+  // In case WT61 already is at 9600
+  imu_send_cmd(0x52);  // Reset yaw (for the sake of it)
+  delay(50);
+  imu_send_cmd(0x65);  // Flat mounting mode
+  delay(50);
+  imu_send_cmd(0x64);  // 9600 bauds / 20Hz report
+  delay(150);          // Let WT61 process config
+
+
+  rxIndex = 0;
+  currentData = {0};
+}
+
+bool imu_update() {
+  bool gotPacket = false;
+
+  while (imuSerial.available()) {
+    uint8_t c = imuSerial.read();
+
+    // State machine: look for header, then collect packet
+    if (rxIndex == 0) {
+      if (c == PACKET_HEADER) {
+        rxBuf[rxIndex++] = c;
+      }
+      // else: discard, wait for sync
+    } else {
+      rxBuf[rxIndex++] = c;
+
+      if (rxIndex >= PACKET_SIZE) {
+        processPacket();
+        rxIndex = 0;
+        gotPacket = true;
+      }
+    }
+  }
+
+  return gotPacket;
+}
+
+const ImuData& imu_get_data() {
+  // Apply calibration offsets if calibrated
+  // Using a static to avoid creating new struct each call
+  static ImuData calibratedData;
+
+  if (calibrated) {
+    calibratedData.ax = currentData.ax - offsets.ax;
+    calibratedData.ay = currentData.ay - offsets.ay;
+    calibratedData.az = currentData.az - offsets.az;
+    calibratedData.gx = currentData.gx - offsets.gx;
+    calibratedData.gy = currentData.gy - offsets.gy;
+    calibratedData.gz = currentData.gz - offsets.gz;
+    calibratedData.roll = currentData.roll - offsets.roll;
+    calibratedData.pitch = currentData.pitch - offsets.pitch;
+    calibratedData.yaw = currentData.yaw - offsets.yaw;
+    calibratedData.lastUpdate = currentData.lastUpdate;
+    return calibratedData;
+  }
+
+  return currentData;
+}
+
+bool imu_is_fresh(unsigned long timeout_ms) {
+  return (millis() - currentData.lastUpdate) < timeout_ms;
+}
+
+void imu_calibrate() {
+  const int SAMPLES = 5;  // ~250ms at 20Hz IMU rate
+
+  // Accumulators for averaging
+  float sum_ax = 0, sum_ay = 0, sum_az = 0;
+  float sum_gx = 0, sum_gy = 0, sum_gz = 0;
+  float sum_roll = 0, sum_pitch = 0, sum_yaw = 0;
+
+  int count = 0;
+  unsigned long lastUpdate = currentData.lastUpdate;
+
+  // Block until we've collected enough samples
+  while (count < SAMPLES) {
+    imu_update();
+
+    if (currentData.lastUpdate != lastUpdate) {
+      // New angle packet arrived (lastUpdate only changes on angle packets)
+      sum_ax += currentData.ax;
+      sum_ay += currentData.ay;
+      sum_az += currentData.az;
+      sum_gx += currentData.gx;
+      sum_gy += currentData.gy;
+      sum_gz += currentData.gz;
+      sum_roll += currentData.roll;
+      sum_pitch += currentData.pitch;
+      sum_yaw += currentData.yaw;
+
+      lastUpdate = currentData.lastUpdate;
+      count++;
+    }
+  }
+
+  // Store averaged offsets
+  offsets.ax = sum_ax / SAMPLES;
+  offsets.ay = sum_ay / SAMPLES;
+  offsets.az = sum_az / SAMPLES;
+  offsets.gx = sum_gx / SAMPLES;
+  offsets.gy = sum_gy / SAMPLES;
+  offsets.gz = sum_gz / SAMPLES;
+  offsets.roll = sum_roll / SAMPLES;
+  offsets.pitch = sum_pitch / SAMPLES;
+  offsets.yaw = sum_yaw / SAMPLES;
+
+  calibrated = true;
+}
+
+bool imu_is_calibrated() {
+  return calibrated;
+}
+
+void imu_send_cmd(uint8_t cmd) {
+  const uint8_t packet[] = {0xFF, 0xAA, cmd};
+  imuSerial.write(packet, 3);
+  imuSerial.flush();
+}

arduino/main/imu.h

@@ -0,0 +1,50 @@
+#ifndef IMU_H
+#define IMU_H
+
+#include <Arduino.h>
+
+// WT61 IMU data structure
+struct ImuData {
+  // Acceleration (g)
+  float ax, ay, az;
+  // Angular velocity (deg/s)
+  float gx, gy, gz;
+  // Euler angles (degrees)
+  float roll, pitch, yaw;
+  // Timestamp of last valid packet (millis)
+  unsigned long lastUpdate;
+};
+
+// Initialize IMU serial (call in setup)
+void imu_init();
+
+// Process incoming bytes - call frequently in loop
+// Returns true if new complete packet was parsed
+bool imu_update();
+
+// Get latest IMU data
+const ImuData& imu_get_data();
+
+// Check if IMU data is fresh (updated within timeout_ms)
+bool imu_is_fresh(unsigned long timeout_ms = 200);
+
+// Calibrate IMU - blocks for ~250ms while sampling
+// Sets current orientation as zero reference
+// Note: Zeroes all axes including accel (loses gravity reference)
+//       Revisit once mounting orientation is finalized
+void imu_calibrate();
+
+// Check if calibration has been performed
+bool imu_is_calibrated();
+
+// Send command to IMU (see IMU.md for command list)
+// Common commands: 0x52 = zero yaw, 0x67 = calibrate accel
+void imu_send_cmd(uint8_t cmd);
+
+// Convenience: zero the yaw angle
+inline void imu_zero_yaw() { imu_send_cmd(0x52); }
+
+// Convenience: calibrate accelerometer (keep module level!)
+inline void imu_calibrate_accel() { imu_send_cmd(0x67); }
+
+#endif

arduino/main/main.ino

@@ -2,24 +2,82 @@
 // Motorcycle telemetry hub
 
 #include "voltage.h"
+#include "imu.h"
+#include "rpm.h"
+#include "gear.h"
+#include "comms.h"
+
+// Timing
+static const unsigned long TELEMETRY_INTERVAL_MS = 100;  // 10Hz telemetry
+static unsigned long lastTelemetryTime = 0;
 
 void setup() {
-  Serial.begin(9600);
   pinMode(LED_BUILTIN, OUTPUT);
 
+  comms_init();    // Hardware Serial first so we can debug
+  Serial.println(F("[INIT] comms ok"));
+
   voltage_init();
+  Serial.println(F("[INIT] voltage ok"));
+
+  imu_init();      // AltSoftSerial on pins 8(RX)/9(TX)
+  Serial.println(F("[INIT] imu ok"));
+
+  rpm_init();
+  gear_init();
+  Serial.println(F("[INIT] rpm/gear ok"));
+
+  // Let IMU warm up a bit before calibrating
+  // (WT61 needs a moment to stabilize after power-on)
+  delay(500);
+
+  Serial.println(F("[INIT] calibrating..."));
+  // Zero calibration - current position becomes reference
+  // Blocks for ~250ms while sampling
+  imu_calibrate();
+  Serial.println(F("[INIT] calibration done, entering loop"));
 }
 
 void loop() {
-  // Report battery voltage
-  Serial.print("V_bat: ");
-  Serial.print(voltage_read(), 2);
-  Serial.println("V");
+  // Always poll IMU - it's streaming at 20Hz
+  imu_update();
 
-  // Heartbeat blink
-  digitalWrite(LED_BUILTIN, HIGH);
-  delay(50);
-  digitalWrite(LED_BUILTIN, LOW);
+  // Update mock RPM (ramping)
+  rpm_update();
 
-  delay(1000);  // 1Hz update rate
+  // Process any commands from Pi
+  if (comms_update()) {
+    const char* cmd = comms_get_command();
+    // Future: handle commands like "PING", "SET_RATE", etc.
+    // For now, echo back as acknowledgment
+    if (cmd[0] != '\0') {
+      comms_send("ACK", cmd);
+    }
+  }
+
+  // Send telemetry at fixed interval
+  unsigned long now = millis();
+  if (now - lastTelemetryTime >= TELEMETRY_INTERVAL_MS) {
+    lastTelemetryTime = now;
+    sendTelemetry();
+  }
+
+  // Heartbeat - quick blink if IMU fresh, slow blink if stale
+  static unsigned long lastBlink = 0;
+  unsigned long blinkInterval = imu_is_fresh() ? 500 : 2000;
+  if (now - lastBlink >= blinkInterval) {
+    lastBlink = now;
+    digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
+  }
+}
+
+void sendTelemetry() {
+  // Send all telemetry in a single TSV frame
+  float voltage = voltage_read();
+  const ImuData& imu = imu_get_data();
+  bool imu_valid = imu_is_fresh();
+  int rpm = rpm_get();
+  int gear = gear_get(rpm);
+
+  comms_send_telemetry(voltage, imu, imu_valid, rpm, gear);
 }

arduino/main/rpm.cpp

@@ -0,0 +1,28 @@
+#include "rpm.h"
+#include <Arduino.h>
+
+// Mock RPM: ramps up/down between idle and redline
+static int _rpm = 800;
+static unsigned long _lastUpdate = 0;
+static const unsigned long RPM_UPDATE_INTERVAL_MS = 100;  // 10Hz ramp rate
+
+void rpm_init() {
+  _rpm = 800;
+  _lastUpdate = 0;
+}
+
+void rpm_update() {
+  unsigned long now = millis();
+  if (now - _lastUpdate < RPM_UPDATE_INTERVAL_MS) {
+    return;  // Not time yet
+  }
+  _lastUpdate = now;
+
+  // +10 RPM every 100ms = ~7s to sweep 800-8000
+  _rpm += 10;
+  if (_rpm >= 8000) { _rpm = 800; }
+}
+
+int rpm_get() {
+  return _rpm;
+}

arduino/main/rpm.h

@@ -0,0 +1,8 @@
+#ifndef RPM_H
+#define RPM_H
+
+void rpm_init();
+void rpm_update();      // Call in loop
+int rpm_get();          // Returns current RPM (0 if invalid)
+
+#endif

arduino/main/voltage.cpp

@@ -10,18 +10,51 @@ static const int PIN_VBAT = A0;
 static const float DIVIDER_RATIO = 47.0 / (100.0 + 47.0);  // ~0.3197
 static const float ADC_REF = 5.0;
 static const int ADC_MAX = 1023;
+static const float OFFSET = 0.2; // calib
+
+// Sliding window smoother (max 32 samples to keep RAM usage sane)
+static const int MAX_WINDOW = 32;
+static int _samples[MAX_WINDOW];
+static int _windowSize = 20;  // Active window size
+static int _sampleIndex = 0;
+static long _sampleSum = 0;
 
 void voltage_init() {
-  // analogRead doesn't need explicit pinMode, but here for future config
-  // e.g., could switch to internal 1.1V reference for different range
+  voltage_set_smoothing(20);  // Default 20 samples
+}
+
+void voltage_set_smoothing(int windowSize) {
+  // Clamp to valid range
+  if (windowSize < 1) windowSize = 1;
+  if (windowSize > MAX_WINDOW) windowSize = MAX_WINDOW;
+  _windowSize = windowSize;
+
+  // Pre-fill window with current reading
+  int initial = analogRead(PIN_VBAT);
+  for (int i = 0; i < _windowSize; i++) {
+    _samples[i] = initial;
+  }
+  _sampleSum = (long)initial * _windowSize;
+  _sampleIndex = 0;
 }
 
 int voltage_read_raw() {
   return analogRead(PIN_VBAT);
 }
 
-float voltage_read() {
-  int raw = voltage_read_raw();
-  float vDivider = (raw / (float)ADC_MAX) * ADC_REF;
-  return vDivider / DIVIDER_RATIO;
+int voltage_read_smoothed() {
+  int raw = analogRead(PIN_VBAT);
+
+  _sampleSum -= _samples[_sampleIndex];   // Remove oldest
+  _samples[_sampleIndex] = raw;            // Store new
+  _sampleSum += raw;                       // Add new
+  _sampleIndex = (_sampleIndex + 1) % _windowSize;
+
+  return _sampleSum / _windowSize;
+}
+
+float voltage_read() {
+  int raw = voltage_read_smoothed();
+  float vDivider = (raw / (float)ADC_MAX) * ADC_REF;
+  return vDivider / DIVIDER_RATIO + OFFSET;
 }

arduino/main/voltage.h

@@ -6,10 +6,17 @@
 // Initialize voltage monitoring (call in setup)
 void voltage_init();
 
-// Read battery voltage, returns volts (e.g., 12.5)
+// Set smoothing window size (1-32 samples, default 20)
+// Resets the buffer with current reading
+void voltage_set_smoothing(int windowSize);
+
+// Read battery voltage (smoothed), returns volts (e.g., 12.5)
 float voltage_read();
 
-// Read raw ADC value (0-1023)
+// Read smoothed ADC value (averaged over window)
+int voltage_read_smoothed();
+
+// Read raw ADC value (0-1023), no smoothing
 int voltage_read_raw();
 
 #endif

pi/backend/arduino_service.py

@@ -1,6 +1,7 @@
 """Arduino service - connects to Arduino Nano via serial, buffers telemetry."""
 
 import json
+import math
 import re
 import threading
 import time
@@ -17,7 +18,10 @@ except ImportError:
 class ArduinoService:
     """Threaded Arduino serial reader with buffering and auto-reconnect."""
 
-    # Regex patterns for legacy text protocol
+    # TSV field names (order per PROTOCOL.md)
+    TSV_FIELDS = ['voltage', 'ax', 'ay', 'az', 'gx', 'gy', 'gz', 'roll', 'pitch', 'yaw', 'rpm', 'gear']
+
+    # Regex patterns for legacy text protocol (backwards compatibility)
     PATTERNS = {
         "voltage": re.compile(r"V_bat:\s*(\d+\.?\d*)V?", re.IGNORECASE),
         "rpm": re.compile(r"RPM:\s*(\d+)", re.IGNORECASE),
@@ -30,7 +34,7 @@ class ArduinoService:
 
     def __init__(
         self,
-        port: str = "/dev/ttyUSB0",
+        port: str = "/dev/serial0",
         baudrate: int = 115200,
         buffer_size: int = 100,
     ):
@@ -53,6 +57,10 @@ class ArduinoService:
         self._serial: Any = None
         self._serial_lock = threading.Lock()
 
+        # Periodic status logging
+        self._last_status_log = 0.0
+        self._frame_count = 0
+
     def set_on_data(self, callback):
         """Set callback for new telemetry data. Called with data dict."""
         self._on_data_callback = callback
@@ -135,10 +143,8 @@ class ArduinoService:
     def _connect_and_read(self):
         """Connect to Arduino serial and read data."""
         if serial is None:
-            # Stub mode - no pyserial installed
-            print("[Arduino] pyserial not installed, running in stub mode")
-            self._stub_mode()
-            return
+            print("[Arduino] pyserial not installed, cannot connect")
+            return  # Will retry via _reader_loop after 5s
 
         try:
             ser = serial.Serial(
@@ -147,24 +153,26 @@ class ArduinoService:
                 timeout=1.0,
             )
         except serial.SerialException as e:
-            print(f"[Arduino] Cannot open {self.port}: {e}, falling back to stub mode")
-            self._stub_mode()
-            return
+            print(f"[Arduino] Cannot open {self.port}: {e}")
+            return  # Will retry via _reader_loop after 5s
 
         try:
             # Store serial handle for send_command()
             with self._serial_lock:
                 self._serial = ser
             self._connected = True
+            self._last_status_log = time.time()
+            self._frame_count = 0
             print(f"[Arduino] Connected to {self.port} @ {self.baudrate} baud")
 
             while self._running:
                 try:
-                    line = ser.readline().decode("utf-8", errors="ignore").strip()
+                    # Read null-terminated line (TSV protocol)
+                    line = self._read_null_terminated(ser)
                     if not line:
                         continue
 
-                    # Check for ACK responses first
+                    # Check for ACK responses first (legacy newline-terminated)
                     ack_match = self.ACK_PATTERN.match(line)
                     if ack_match:
                         cmd, status, extra = ack_match.groups()
@@ -178,7 +186,7 @@ class ArduinoService:
                         with self._lock:
                             # Merge new values into latest (preserve old values for partial updates)
                             for key, val in data.items():
-                                if val is not None:
+                                if val is not None and not (isinstance(val, float) and math.isnan(val)):
                                     self._latest[key] = val
                             self._latest["time"] = data["time"]
                             self._buffer.append(self._latest.copy())
@@ -187,6 +195,20 @@ class ArduinoService:
                         if self._on_data_callback:
                             self._on_data_callback(self._latest.copy())
 
+                        # Periodic status log (every 5s)
+                        self._frame_count += 1
+                        now = time.time()
+                        if now - self._last_status_log >= 5.0:
+                            elapsed = now - self._last_status_log
+                            fps = self._frame_count / elapsed
+                            v = self._latest.get('voltage', 0)
+                            rpm = self._latest.get('rpm', 0)
+                            gear = self._latest.get('gear', 0)
+                            roll = self._latest.get('roll', 0)
+                            print(f"[Arduino] {fps:.1f} fps | V={v:.1f} RPM={int(rpm)} G={int(gear)} roll={roll:.1f}°")
+                            self._last_status_log = now
+                            self._frame_count = 0
+
                 except serial.SerialException as e:
                     print(f"[Arduino] Serial error: {e}")
                     break
@@ -197,13 +219,40 @@ class ArduinoService:
                 self._serial = None
             ser.close()
 
-    def _parse_line(self, line: str) -> dict[str, Any] | None:
-        """Parse a line from Arduino - JSON first, fallback to regex.
+    def _read_null_terminated(self, ser) -> str:
+        """Read bytes until null terminator or newline (fallback for legacy)."""
+        buf = bytearray()
+        while self._running:
+            byte = ser.read(1)
+            if not byte:
+                # Timeout
+                if buf:
+                    # Return partial buffer if we have data
+                    return buf.decode("utf-8", errors="ignore").strip()
+                return ""
+            if byte == b'\x00' or byte == b'\n' or byte == b'\r':
+                # End of frame
+                if buf:
+                    return buf.decode("utf-8", errors="ignore").strip()
+                # Skip empty lines / consecutive terminators
+                continue
+            buf.append(byte[0])
+            # Safety limit
+            if len(buf) > 256:
+                return buf.decode("utf-8", errors="ignore").strip()
 
+    def _parse_line(self, line: str) -> dict[str, Any] | None:
+        """Parse a line from Arduino - TSV first, then JSON, fallback to regex.
+
+        TSV format: 12.45\t0.02\t-0.01\t... (10 fields, per PROTOCOL.md)
         JSON format: {"v":12.45,"rpm":4500,"eng":85,"gear":3}
         Legacy text: V_bat: 12.45V
         """
-        # Try JSON first (production format)
+        # Try TSV first (new protocol)
+        if '\t' in line:
+            return self._parse_tsv(line)
+
+        # Try JSON (may still be used for special messages)
         try:
             obj = json.loads(line)
             return {
@@ -225,31 +274,35 @@ class ArduinoService:
 
         return result if result else None
 
-    def _stub_mode(self):
-        """Fake data for testing without Arduino connected."""
-        import random
+    def _parse_tsv(self, line: str) -> dict[str, Any] | None:
+        """Parse TSV telemetry frame per PROTOCOL.md.
 
-        _rpm = 3000
+        Fields: voltage, ax, ay, az, gx, gy, gz, roll, pitch, yaw
+        Empty fields (stale IMU) become NaN.
+        """
+        fields = line.split('\t')
+        if len(fields) != len(self.TSV_FIELDS):
+            # Wrong field count - might be debug output or malformed
+            return None
 
-        while self._running:
-            self._connected = True
-            data = {
-                "time": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
-                "voltage": round(12.0 + random.uniform(-0.5, 0.8), 2),
-                "rpm": _rpm if random.random() > 0.1 else None,
-                "eng_temp": random.randint(60, 95),
-                "gear": random.randint(1, 6) if random.random() > 0.2 else 0,  # 0 = neutral
-            }
-            _rpm += 10
-            if _rpm > 7500:
-                _rpm = 500
+        result = {}
+        for i, name in enumerate(self.TSV_FIELDS):
+            val_str = fields[i].strip()
+            if val_str == '':
+                # Empty field = stale/missing data
+                result[name] = float('nan')
+            else:
+                try:
+                    result[name] = float(val_str)
+                except ValueError:
+                    result[name] = float('nan')
 
-            with self._lock:
-                self._latest = data
-                self._buffer.append(data)
+        # IMU axis correction for mounting orientation
+        # Pitch/yaw inverted for motorcycle frame alignment (roll left as-is)
+        if 'pitch' in result and not math.isnan(result['pitch']):
+            result['pitch'] = -result['pitch']
+        if 'yaw' in result and not math.isnan(result['yaw']):
+            result['yaw'] = -result['yaw']
 
-            # Invoke callback with new data
-            if self._on_data_callback:
-                self._on_data_callback(data)
+        return result
 
-            time.sleep(0.5)  # 2Hz stub updates

pi/backend/main.py

@@ -20,8 +20,8 @@ socketio = SocketIO(app, async_mode="gevent", cors_allowed_origins="*")
 gps = GPSService()
 arduino = ArduinoService()
 
-# Throttles for emission rate limiting (2Hz for arduino, 1Hz for GPS)
-arduino_throttle = Throttle(min_interval=0.5)  # 2Hz max
+# Throttles for emission rate limiting (20Hz for arduino, 1Hz for GPS)
+arduino_throttle = Throttle(min_interval=0.05)  # 20Hz max
 gps_throttle = Throttle(min_interval=1.0)      # 1Hz max
 
 # Track connected clients
@@ -157,7 +157,7 @@ def throttle_flusher():
     """Periodically flush pending throttled data."""
     import gevent
     while True:
-        gevent.sleep(0.5)
+        gevent.sleep(0.05)  # 20Hz flush rate
 
         if arduino_throttle.has_pending:
             arduino_throttle.flush(lambda d: socketio.emit("arduino", d))

pi/ui/lib/app_root.dart

@@ -1,4 +1,6 @@
+import 'dart:convert';
 import 'package:flutter/material.dart';
+import 'package:http/http.dart' as http;
 
 import 'screens/splash_screen.dart';
 import 'screens/dashboard_screen.dart';
@@ -36,14 +38,12 @@ class _AppRootState extends State<AppRoot> {
     setState(() => _initStatus = 'Loading config...');
     await ConfigService.instance.load();
 
-    // Simulate init checks - replace with real checks later
-    // (UART, GPS, sensors, etc.)
-
     setState(() => _initStatus = 'Checking systems...');
-    await Future.delayed(const Duration(milliseconds: 800));
+    await Future.delayed(const Duration(milliseconds: 500));
 
-    setState(() => _initStatus = 'UART: standby');
-    await Future.delayed(const Duration(milliseconds: 400));
+    // Check UART connection via backend health endpoint
+    setState(() => _initStatus = 'UART: connecting...');
+    await _waitForUart();
 
     setState(() => _initStatus = 'GPS: standby');
     await Future.delayed(const Duration(milliseconds: 400));
@@ -61,6 +61,42 @@ class _AppRootState extends State<AppRoot> {
     setState(() => _initialized = true);
   }
 
+  /// Poll backend health endpoint until Arduino is connected
+  Future<void> _waitForUart() async {
+    final backendUrl = ConfigService.instance.backendUrl;
+    const maxAttempts = 30; // ~30 seconds max wait
+    const retryDelay = Duration(seconds: 1);
+
+    for (int attempt = 0; attempt < maxAttempts; attempt++) {
+      try {
+        final response = await http
+            .get(Uri.parse('$backendUrl/health'))
+            .timeout(const Duration(seconds: 2));
+
+        if (response.statusCode == 200) {
+          final data = jsonDecode(response.body) as Map<String, dynamic>;
+          final arduinoOk = data['arduino_connected'] == true;
+
+          if (arduinoOk) {
+            setState(() => _initStatus = 'UART: OK');
+            await Future.delayed(const Duration(milliseconds: 300));
+            return;
+          }
+        }
+      } catch (e) {
+        // Backend not reachable yet - keep trying
+      }
+
+      // Not connected yet
+      setState(() => _initStatus = 'UART: waiting...');
+      await Future.delayed(retryDelay);
+    }
+
+    // Timeout - proceed anyway (UI will show stale data indicators)
+    setState(() => _initStatus = 'UART: timeout');
+    await Future.delayed(const Duration(milliseconds: 500));
+  }
+
   @override
   Widget build(BuildContext context) {
     // Determine which screen to show (priority: overheat > splash > dashboard)

pi/ui/lib/screens/dashboard_screen.dart

@@ -10,6 +10,7 @@ import '../widgets/stat_box.dart';
 import '../widgets/stat_box_main.dart';
 import '../widgets/system_bar.dart';
 import '../widgets/debug_console.dart';
+import '../widgets/whiskey_mark.dart';
 
 // test service for triggers
 import '../services/test_flipflop_service.dart';
@@ -41,6 +42,8 @@ class _DashboardScreenState extends State<DashboardScreen> {
   double? _voltage;
   int? _engineTemp;
   int? _gear;
+  double? _roll;
+  double? _pitch;
 
   // From backend - GPS data
   double? _gpsSpeed;
@@ -66,6 +69,8 @@ class _DashboardScreenState extends State<DashboardScreen> {
         _rpm = data.rpm;
         _engineTemp = data.engTemp;
         _gear = data.gear;
+        _roll = data.roll;
+        _pitch = data.pitch;
       });
     });
 
@@ -99,6 +104,8 @@ class _DashboardScreenState extends State<DashboardScreen> {
       _rpm = cachedArduino.rpm;
       _engineTemp = cachedArduino.engTemp;
       _gear = cachedArduino.gear;
+      _roll = cachedArduino.roll;
+      _pitch = cachedArduino.pitch;
     }
 
     final cachedGps = WebSocketService.instance.latestGps;
@@ -175,12 +182,17 @@ class _DashboardScreenState extends State<DashboardScreen> {
                     child: Row(
                       children: [
                         // RPM from Arduino
-                        StatBoxMain(
-                          value: _formatInt(_rpm),
-                          label: 'RPM',
+                        // StatBoxMain(
+                        //   value: _formatInt(_rpm),
+                        //   label: 'RPM',
+                        // ),
+                        // Attitude indicator (whiskey mark)
+                        Expanded(
+                          child: WhiskeyMark(
+                            roll: _roll,
+                            pitch: _pitch,
+                          ),
                         ),
-                        // Add second StatBoxMain here for 2-up layout:
-                        // StatBoxMain(value: '4500', unit: 'rpm', label: 'TACH'),
                       ],
                     ),
                   ),
@@ -191,8 +203,8 @@ class _DashboardScreenState extends State<DashboardScreen> {
                     child: Row(
                       mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                       children: [
-                        StatBox(value: _formatInt(_rpm), label: 'RPM'),
-                        StatBox(value: _formatInt(_engineTemp), unit: '°C', label: 'ENG'),
+                        StatBox(value: _formatInt(_rpm), label: 'RPM', isWarning: () => (_rpm ?? 0) > 4000),
+                        StatBox(value: _formatInt(_engineTemp), unit: '°C', label: 'ENG', isWarning: () => (_engineTemp ?? 0) > 120),
                         StatBox(value: _formatGear(_gear), label: 'GEAR'),
                       ],
                     ),

pi/ui/lib/services/backend_service.dart

@@ -2,14 +2,16 @@ import 'dart:async';
 import 'dart:convert';
 import 'package:http/http.dart' as http;
 
-/// Data from Arduino (voltage, rpm, engine temp, gear)
+/// Data from Arduino (voltage, rpm, engine temp, gear, IMU)
 class ArduinoData {
   final double? voltage;
   final int? rpm;
   final int? engTemp;
   final int? gear; // 0 = neutral, 1-6 = gear
+  final double? roll;  // Euler angle in degrees (negative = left, positive = right)
+  final double? pitch; // Euler angle in degrees (negative = nose down)
 
-  ArduinoData({this.voltage, this.rpm, this.engTemp, this.gear});
+  ArduinoData({this.voltage, this.rpm, this.engTemp, this.gear, this.roll, this.pitch});
 
   factory ArduinoData.fromJson(Map<String, dynamic> json) {
     return ArduinoData(
@@ -17,6 +19,8 @@ class ArduinoData {
       rpm: (json['rpm'] as num?)?.toInt(),
       engTemp: (json['eng_temp'] as num?)?.toInt(),
       gear: (json['gear'] as num?)?.toInt(),
+      roll: (json['roll'] as num?)?.toDouble(),  // IMU mounted with axes swapped
+      pitch: (json['pitch'] as num?)?.toDouble(),
     );
   }
 }

pi/ui/lib/services/config_service.dart

@@ -86,4 +86,11 @@ class ConfigService {
     if (value is String && value.isNotEmpty) return value;
     return _defaultNavigator;
   }
+
+  /// Backend URL for API calls
+  String get backendUrl {
+    final value = _config?['backend_url'];
+    if (value is String && value.isNotEmpty) return value;
+    return 'http://127.0.0.1:5000';
+  }
 }

pi/ui/lib/services/websocket_service.dart

@@ -184,7 +184,10 @@ class WebSocketService {
         final arduino = ArduinoData.fromJson(data);
         _latestArduino = arduino;
         _arduinoController.add(arduino);
-        _log('ard: ${arduino.rpm ?? "-"}rpm ${arduino.voltage ?? "-"}V g${arduino.gear ?? "-"}');
+        final rollStr = arduino.roll != null ? 'r${arduino.roll!.round()}' : '';
+        final pitchStr = arduino.pitch != null ? 'p${arduino.pitch!.round()}' : '';
+        final imuStr = (rollStr.isNotEmpty || pitchStr.isNotEmpty) ? ' $rollStr$pitchStr' : '';
+        _log('ard: ${arduino.rpm ?? "-"}rpm ${arduino.voltage ?? "-"}V g${arduino.gear ?? "-"}$imuStr');
       }
     });
 

pi/ui/lib/widgets/navigator_widget.dart

@@ -1,4 +1,5 @@
 import 'dart:io';
+import 'dart:math';
 import 'package:flutter/material.dart';
 import '../services/config_service.dart';
 
@@ -18,14 +19,34 @@ class NavigatorWidget extends StatefulWidget {
   State<NavigatorWidget> createState() => NavigatorWidgetState();
 }
 
-class NavigatorWidgetState extends State<NavigatorWidget> {
+class NavigatorWidgetState extends State<NavigatorWidget>
+    with SingleTickerProviderStateMixin {
   String _emotion = 'default';
+  late AnimationController _shakeController;
+
+  @override
+  void initState() {
+    super.initState();
+    _shakeController = AnimationController(
+      duration: const Duration(milliseconds: 400),
+      vsync: this,
+    );
+  }
+
+  @override
+  void dispose() {
+    _shakeController.dispose();
+    super.dispose();
+  }
 
   /// Change the displayed emotion.
   /// Image file must exist at: {assetsPath}/navigator/{navigator}/{emotion}.png
   void setEmotion(String emotion) {
     if (emotion != _emotion) {
       setState(() => _emotion = emotion);
+      if (emotion == 'surprise') {
+        _shakeController.forward(from: 0);
+      }
     }
   }
 
@@ -40,7 +61,7 @@ class NavigatorWidgetState extends State<NavigatorWidget> {
     final config = ConfigService.instance;
     final basePath = '${config.assetsPath}/navigator/${config.navigator}';
 
-    return Image.file(
+    final image = Image.file(
       File('$basePath/$_emotion.png'),
       fit: BoxFit.contain,
       errorBuilder: (context, error, stackTrace) {
@@ -55,5 +76,19 @@ class NavigatorWidgetState extends State<NavigatorWidget> {
         return const SizedBox.shrink();
       },
     );
+
+    // Shake animation for surprise
+    return AnimatedBuilder(
+      animation: _shakeController,
+      child: image,
+      builder: (context, child) {
+        final shake = sin(_shakeController.value * pi * 6) * 10 *
+            (1 - _shakeController.value); // 6 oscillations, 4px amplitude, decay
+        return Transform.translate(
+          offset: Offset(shake, 0),
+          child: child,
+        );
+      },
+    );
   }
 }

pi/ui/lib/widgets/stat_box.dart

@@ -9,17 +9,23 @@ class StatBox extends StatelessWidget {
   final String label;
   final int flex;
 
+  /// Optional warning predicate - if returns true, value shows in highlight color
+  final bool Function()? isWarning;
+
   const StatBox({
     super.key,
     required this.value,
     this.unit,
     required this.label,
     this.flex = 1,
+    this.isWarning,
   });
 
   @override
   Widget build(BuildContext context) {
     final theme = AppTheme.of(context);
+    final warning = isWarning?.call() ?? false;
+    final valueColor = warning ? theme.highlight : theme.foreground;
 
     return Expanded(
       flex: flex,
@@ -42,7 +48,7 @@ class StatBox extends StatelessWidget {
                       fontSize: baseSize,
                       fontWeight: FontWeight.w400,
                       fontFeatures: const [FontFeature.tabularFigures()],
-                      color: theme.foreground,
+                      color: valueColor,
                       height: 1,
                     ),
                   ),

pi/ui/lib/widgets/whiskey_mark.dart

@@ -0,0 +1,233 @@
+import 'dart:math' as math;
+import 'package:flutter/material.dart';
+
+import '../theme/app_theme.dart';
+
+/// Primitive attitude indicator (whiskey mark) displaying roll/pitch.
+///
+/// Visual: tilting horizon line based on roll angle
+///   Hard left  (-45°+):  ╲
+///   Left       (-15°):   ╲─
+///   Level      (0°):      ─
+///   Right      (+15°):   ─╱
+///   Hard right (+45°+):    ╱
+///
+/// Below the horizon: numeric readout "R: -12° P: 5°"
+class WhiskeyMark extends StatelessWidget {
+  /// Roll angle in degrees. Negative = left bank, positive = right bank.
+  final double? roll;
+
+  /// Pitch angle in degrees. Negative = nose down, positive = nose up.
+  final double? pitch;
+
+  const WhiskeyMark({
+    super.key,
+    this.roll,
+    this.pitch,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = AppTheme.of(context);
+
+    return LayoutBuilder(
+      builder: (context, constraints) {
+        final size = math.min(constraints.maxWidth, constraints.maxHeight);
+        final horizonSize = size * 0.6;
+        final fontSize = size * 0.12;
+
+        return Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            // Horizon indicator
+            SizedBox(
+              width: horizonSize,
+              height: horizonSize,
+              child: CustomPaint(
+                painter: _HorizonPainter(
+                  roll: roll ?? 0,
+                  pitch: pitch ?? 0,
+                  lineColor: theme.foreground,
+                  borderWeight: 8,
+                  skyColor: theme.subdued,
+                  groundColor: theme.background,
+                ),
+              ),
+            ),
+
+            SizedBox(height: size * 0.05),
+
+            // Numeric readout
+            Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Text(
+                  'Roll: ${_formatAngle(roll)}',
+                  style: TextStyle(
+                    fontSize: fontSize * 0.8,
+                    fontWeight: FontWeight.w400,
+                    fontFeatures: const [FontFeature.tabularFigures()],
+                    color: theme.foreground,
+                  ),
+                ),
+                SizedBox(width: size * 0.1),
+                Text(
+                  'P: ${_formatAngle(pitch)}',
+                  style: TextStyle(
+                    fontSize: fontSize * 0.8,
+                    fontWeight: FontWeight.w400,
+                    fontFeatures: const [FontFeature.tabularFigures()],
+                    color: theme.subdued,
+                  ),
+                ),
+              ],
+            ),
+
+            // Label
+            Text(
+              'ATTITUDE',
+              style: TextStyle(
+                fontSize: fontSize * 0.8,
+                fontWeight: FontWeight.w400,
+                color: theme.subdued,
+                letterSpacing: 1,
+              ),
+            ),
+          ],
+        );
+      },
+    );
+  }
+
+  String _formatAngle(double? angle) {
+    if (angle == null) return '—°';
+    return '${angle.round()}°';
+  }
+}
+
+/// Custom painter for the tilting horizon line
+class _HorizonPainter extends CustomPainter {
+  final double roll;
+  final double pitch;
+  final double borderWeight;
+  final Color lineColor;
+  final Color skyColor;
+  final Color groundColor;
+
+  _HorizonPainter({
+    required this.roll,
+    required this.pitch,
+    required this.borderWeight,
+    required this.lineColor,
+    required this.skyColor,
+    required this.groundColor,
+  });
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final center = Offset(size.width / 2, size.height / 2);
+    final radius = math.min(size.width, size.height) / 2;
+
+    // Clip to circle
+    canvas.save();
+    canvas.clipPath(Path()..addOval(Rect.fromCircle(center: center, radius: radius)));
+
+    // Convert roll to radians (negate so positive roll tilts right visually)
+    final rollRad = -roll * math.pi / 180;
+
+    // Pitch offset (positive pitch moves horizon down, showing more sky)
+    // Scale: 90° pitch = full radius displacement
+    final pitchOffset = (pitch / 90) * radius;
+
+    // Calculate horizon line endpoints
+    // The horizon is a horizontal line that we rotate by roll and offset by pitch
+    final horizonY = center.dy + pitchOffset;
+
+    // Paint sky (above horizon)
+    final skyPaint = Paint()..color = skyColor;
+    final groundPaint = Paint()..color = groundColor;
+
+    // Create rotated horizon path
+    canvas.save();
+    canvas.translate(center.dx, center.dy);
+    canvas.rotate(rollRad);
+    canvas.translate(-center.dx, -center.dy);
+
+    // Sky rectangle (above horizon)
+    canvas.drawRect(
+      Rect.fromLTRB(
+        center.dx - radius * 2,
+        center.dy - radius * 2,
+        center.dx + radius * 2,
+        horizonY,
+      ),
+      skyPaint,
+    );
+
+    // Ground rectangle (below horizon)
+    canvas.drawRect(
+      Rect.fromLTRB(
+        center.dx - radius * 2,
+        horizonY,
+        center.dx + radius * 2,
+        center.dy + radius * 2,
+      ),
+      groundPaint,
+    );
+
+    // Horizon line
+    final linePaint = Paint()
+      ..color = lineColor
+      ..strokeWidth = 2
+      ..style = PaintingStyle.stroke;
+
+    canvas.drawLine(
+      Offset(center.dx - radius, horizonY),
+      Offset(center.dx + radius, horizonY),
+      linePaint,
+    );
+
+    canvas.restore();
+
+    // Draw circle border
+    final borderPaint = Paint()
+      ..color = lineColor.withValues(alpha: 0.5)
+      ..strokeWidth = borderWeight
+      ..style = PaintingStyle.stroke;
+
+    canvas.drawCircle(center, radius - 1, borderPaint);
+
+    // Draw center reference mark (fixed, doesn't rotate)
+    final refPaint = Paint()
+      ..color = lineColor
+      ..strokeWidth = borderWeight * 0.8
+      ..style = PaintingStyle.stroke;
+
+    // Small wings
+    canvas.drawLine(
+      Offset(center.dx - radius * 0.3, center.dy),
+      Offset(center.dx - radius * 0.1, center.dy),
+      refPaint,
+    );
+    canvas.drawLine(
+      Offset(center.dx + radius * 0.1, center.dy),
+      Offset(center.dx + radius * 0.3, center.dy),
+      refPaint,
+    );
+    // Center vertical line
+    canvas.drawLine(
+      Offset(center.dx, center.dy - radius * 0.05),
+      Offset(center.dx, center.dy + radius * 0.1),
+      refPaint,
+    );
+
+    canvas.restore();
+  }
+
+  @override
+  bool shouldRepaint(_HorizonPainter oldDelegate) {
+    return roll != oldDelegate.roll ||
+        pitch != oldDelegate.pitch ||
+        lineColor != oldDelegate.lineColor;
+  }
+}

scripts/deploy_backend.py

@@ -17,6 +17,7 @@ SCRIPT_DIR = Path(__file__).parent.resolve()
 PROJECT_ROOT = SCRIPT_DIR.parent
 CONFIG_FILE = SCRIPT_DIR / "deploy_target.json"
 BACKEND_DIR = PROJECT_ROOT / "pi" / "backend"
+SERVICE_FILE = SCRIPT_DIR / "smartserow-backend.service"
 
 
 def run(cmd: list[str], check: bool = True, **kwargs) -> subprocess.CompletedProcess:
@@ -72,6 +73,7 @@ def deploy(restart: bool = False) -> bool:
         "--exclude", "*.pyc",
         "--exclude", ".venv",
         "--exclude", ".ruff_cache",
+        "--exclude", "uv.lock",  # Let Pi generate its own lockfile
         f"{BACKEND_DIR}/",
         f"{ssh_target}:{remote_path}/",
     ])
@@ -88,6 +90,16 @@ def deploy(restart: bool = False) -> bool:
         print("WARNING: uv sync failed - dependencies may be out of date")
         print("Make sure uv is installed on Pi: curl -LsSf https://astral.sh/uv/install.sh | sh")
 
+    # Deploy service file if it exists
+    if SERVICE_FILE.exists():
+        print()
+        print("Deploying systemd service file...")
+        run(["scp", str(SERVICE_FILE), f"{ssh_target}:/tmp/"])
+        run([
+            "ssh", ssh_target,
+            f"sudo mv /tmp/{SERVICE_FILE.name} /etc/systemd/system/ && sudo systemctl daemon-reload"
+        ])
+
     # Restart service if requested
     if restart:
         print()