diff --git a/platformio.ini b/platformio.ini
index e78124a40b..bb08e5f223 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -138,6 +138,7 @@ build_flags =
   -D ENV_INCLUDE_VL53L0X=1
   -D ENV_INCLUDE_BME680=1
   -D ENV_INCLUDE_BMP085=1
+  -D ENV_INCLUDE_OPT3001=1
 lib_deps =
   adafruit/Adafruit INA3221 Library @ ^1.0.1
   adafruit/Adafruit INA219 @ ^1.2.3
diff --git a/src/helpers/sensors/EnvironmentSensorManager.cpp b/src/helpers/sensors/EnvironmentSensorManager.cpp
index e2f0d33e72..b2f7ce5804 100644
--- a/src/helpers/sensors/EnvironmentSensorManager.cpp
+++ b/src/helpers/sensors/EnvironmentSensorManager.cpp
@@ -160,6 +160,14 @@ static Adafruit_VL53L0X VL53L0X;
 static RAK12035_SoilMoisture RAK12035;
 #endif
 
+#if ENV_INCLUDE_OPT3001
+#ifndef TELEM_OPT3001_ADDRESS
+#define TELEM_OPT3001_ADDRESS 0x44 // OPT3001 ambient light sensor (RAK1903) I2C address
+#endif
+#include "OPT3001.h"
+static OPT3001 OPT3001;
+#endif
+
 #if ENV_INCLUDE_GPS && defined(RAK_BOARD) && !defined(RAK_WISMESH_TAG)
 #define RAK_WISBLOCK_GPS
 #endif
@@ -401,6 +409,7 @@ static void query_ina260(uint8_t ch, uint8_t, CayenneLPP& lpp) {
 static uint8_t init_ina226(TwoWire*, uint8_t) {
   // INA226 static instance was constructed with address and wire.
   if (!INA226.begin()) return 0;
+  if (INA226.getManufacturerID() != 0x5449 || INA226.getDieID() != 0x2260) return 0;
   INA226.setMaxCurrentShunt(TELEM_INA226_MAX_AMP, TELEM_INA226_SHUNT_VALUE);
   return 1;
 }
@@ -531,6 +540,24 @@ static void query_bme680_bsec(uint8_t ch, uint8_t, CayenneLPP& lpp) {
 }
 #endif
 
+#if ENV_INCLUDE_OPT3001
+static uint8_t init_opt3001(TwoWire* wire, uint8_t addr) {
+  // probe() is read-only. 0x44 may also be an SHT4X or INA226,
+  // so chip is identified by manufacturer/device ID before any
+  // config is written.
+  if(!OPT3001.probe(wire, addr)) return 0;
+  return OPT3001.begin() ? 1 : 0;
+}
+
+static void query_opt3001(uint8_t ch, uint8_t, CayenneLPP& lpp) {
+  float lux;
+  if (OPT3001.readLux(lux)) {
+    lpp.addLuminosity(ch, lux);
+  }
+}
+
+#endif
+
 // ============================================================
 // Sensor descriptor table
 //
@@ -599,6 +626,9 @@ static const SensorDef SENSOR_TABLE[] = {
 #endif
 #if ENV_INCLUDE_RAK12035
   { TELEM_RAK12035_ADDRESS,"RAK12035",     init_rak12035, query_rak12035 },
+#endif
+#if ENV_INCLUDE_OPT3001
+  { TELEM_OPT3001_ADDRESS,"OPT3001",       init_opt3001,  query_opt3001  },
 #endif
   { 0, nullptr, nullptr, nullptr }  // sentinel — keeps the array non-empty
 };
diff --git a/src/helpers/sensors/OPT3001.cpp b/src/helpers/sensors/OPT3001.cpp
new file mode 100644
index 0000000000..9db94bac18
--- /dev/null
+++ b/src/helpers/sensors/OPT3001.cpp
@@ -0,0 +1,56 @@
+#include "OPT3001.h"
+
+bool OPT3001::readReg(uint8_t reg, uint16_t& value) {
+    _wire->beginTransmission(_addr);
+    _wire->write(reg);
+    if (_wire->endTransmission() != 0) return false;
+
+    if (_wire->requestFrom(_addr, (uint8_t)2) != 2) return false;
+    uint16_t msb = _wire->read(); // sequence the two reads
+    uint16_t lsb = _wire->read();
+    value = (msb << 8) | lsb;
+    return true;
+}
+
+bool OPT3001::writeReg(uint8_t reg, uint16_t value) {
+    _wire->beginTransmission(_addr);
+    _wire->write(reg);
+    _wire->write((uint8_t)(value >> 8));
+    _wire->write((uint8_t)(value & 0xFF));
+    return _wire->endTransmission() == 0;
+}
+
+bool OPT3001::probe(TwoWire* wire, uint8_t addr) {
+    _wire = wire;
+    _addr = addr;
+
+    uint16_t id;
+    if (!readReg(OPT3001_REG_MANUFACTURER_ID, id) || id != OPT3001_MANUFACTURER_ID) return false;
+    if (!readReg(OPT3001_REG_DEVICE_ID, id) || id != OPT3001_DEVICE_ID) return false;
+    return true;
+}
+
+bool OPT3001::begin() {
+    _ready = false;
+    return writeReg(OPT3001_REG_CONFIG, OPT3001_CONFIG_CONTINUOUS);
+}
+
+bool OPT3001::readLux(float& lux) {
+    if (!_ready) {
+        // Reading the latched config register clears CRF, however
+        // in continuous mode it is set again after every conversion.
+        // We only need to gate the very first read after begin().
+        uint16_t config;
+        if (!readReg(OPT3001_REG_CONFIG, config)) return false;
+        if ((config & OPT3001_CONFIG_CRF) == 0) return false;
+        _ready = true;
+    }
+
+    uint16_t raw;
+    if (!readReg(OPT3001_REG_RESULT, raw)) return false;
+
+    // Result format: exponent E in [15:12], mantissa R in [11:0]
+    // lux = 0.01 * 2^E * R (full-scale 83865.6 lux)
+    lux = 0.01f * (float)(1u << (raw >> 12)) * (float)(raw & 0x0FFF);
+    return true;
+}
\ No newline at end of file
diff --git a/src/helpers/sensors/OPT3001.h b/src/helpers/sensors/OPT3001.h
new file mode 100644
index 0000000000..b6ae7cc78a
--- /dev/null
+++ b/src/helpers/sensors/OPT3001.h
@@ -0,0 +1,52 @@
+/**
+ * @file OPT3001.h
+ * @author Nick Dunklee
+ * @brief Minimal driver for the TI OPT3001 ambient light sensor
+ *        (used on the RAK1903 WisBlock module).
+ *
+ * Written for MeshCore from the TI OPT3001 datasheet (SBOS681).
+ * https://www.ti.com/lit/ds/sbos681b/sbos681b.pdf
+ *
+ * The default address of 0x44 is shared with other sensors (SHT4x,
+ * INA226), so probe() performs a read-only identity check and no
+ * register is written until the chip is positively ID'd.
+*/
+
+#pragma once
+
+#include <Arduino.h>
+#include <Wire.h>
+
+#define OPT3001_REG_RESULT          0x00
+#define OPT3001_REG_CONFIG          0x01
+#define OPT3001_REG_MANUFACTURER_ID 0x7E
+#define OPT3001_REG_DEVICE_ID       0x7F
+
+#define OPT3001_MANUFACTURER_ID     0x5449  // TI
+#define OPT3001_DEVICE_ID           0x3001
+
+// Automatic full-scale range, 800ms conversions, continuous mode, latched flags
+#define OPT3001_CONFIG_CONTINUOUS   0xCE10
+#define OPT3001_CONFIG_CRF          0x0080  // conversion ready flag
+
+class OPT3001 {
+    TwoWire* _wire;
+    uint8_t  _addr;
+    bool     _ready; // at least one conversion has completed since begin()
+
+    bool readReg(uint8_t reg, uint16_t& value);
+    bool writeReg(uint8_t reg, uint16_t value);
+
+public:
+    OPT3001() : _wire(NULL), _addr(0), _ready(false) { }
+
+    // Read-only identity check (manufacturer + device ID). Safe to call
+    // on a foreign device that happens to share the I2C address.
+    bool probe(TwoWire* wire, uint8_t addr);
+
+    // Start continuous conversions. Call only after probe() succeeds.
+    bool begin();
+
+    // Return false until the first conversion completes.
+    bool readLux(float& lux);
+};
\ No newline at end of file
diff --git a/variants/lilygo_tdeck/platformio.ini b/variants/lilygo_tdeck/platformio.ini
index 00571db93b..4c6cc1d917 100644
--- a/variants/lilygo_tdeck/platformio.ini
+++ b/variants/lilygo_tdeck/platformio.ini
@@ -35,6 +35,7 @@ build_flags =
   -D ENV_INCLUDE_VL53L0X=0
   -D ENV_INCLUDE_BME680=0
   -D ENV_INCLUDE_BMP085=0
+  -D ENV_INCLUDE_OPT3001=0
   -D P_LORA_NSS=9    ; LORA SS pin
   -D P_LORA_RESET=17 ; LORA RST pin
   -D P_LORA_BUSY=13  ; LORA Busy pin