diff --git a/.DS_Store b/.DS_Store
deleted file mode 100644
index bedf0db..0000000
Binary files a/.DS_Store and /dev/null differ
diff --git a/.env.example b/.env.example
index 91cf018..dba611d 100644
--- a/.env.example
+++ b/.env.example
@@ -1,26 +1,73 @@
 # .env.example - Template for environment variables
 # Copy to .env and customize
 
-SECRET_KEY=change-me
+# ============================================================================
+# General
+# ============================================================================
+# SECRET_KEY        - Secret key for web application session signing and
+#                     security features. Use a long random string in production.
+SECRET_KEY=dev-secret-key-change-in-production
 
+# ============================================================================
 # GPON Device
+# ============================================================================
+# GPON_HOST         - IP address or hostname of the GPON ONU/ONT device
+# GPON_PORT         - Management port (Telnet/SSH) for device connection
+# GPON_USERNAME     - Username for GPON device authentication
+# GPON_PASSWORD     - Password for GPON device authentication
 GPON_HOST=192.168.100.1
 GPON_PORT=23
 GPON_USERNAME=leox
 GPON_PASSWORD=leolabs_7
 
+# ============================================================================
 # Web Server
+# ============================================================================
+# LISTEN_HOST       - IP address the web server binds to (0.0.0.0 = all interfaces)
+#                     !! DO NOT CHANGE IN DOCKER - must be 0.0.0.0 for container networking
+# LISTEN_PORT       - Internal port used by the web application (default: 8080)
+#                     !! If changed, also update 'expose' section in docker-compose.yml
+# EXTERNAL_PORT     - Port exposed externally via Caddy reverse proxy (default: 7878)
+#                     Change this to expose the app on different host port
 LISTEN_HOST=0.0.0.0
 LISTEN_PORT=8080
 EXTERNAL_PORT=7878
 
-# Data
+# ============================================================================
+# Data & Polling
+# ============================================================================
+# RRD_DIR           - Filesystem path where RRD databases are stored
+#                     !! DO NOT CHANGE IN DOCKER - must be /data/rrd (mapped to ./data/rrd volume)
+# POLL_INTERVAL     - Data collection interval in seconds (how often device is polled)
 RRD_DIR=/data/rrd
 POLL_INTERVAL=60
 
-# Thresholds
+# ============================================================================
+# Optical & Temperature Thresholds
+# ============================================================================
+# RX_POWER_MIN      - Minimum acceptable RX optical power in dBm (warning below)
+# RX_POWER_MAX      - Maximum acceptable RX optical power in dBm (warning above)
+# TX_POWER_MIN      - Minimum acceptable TX optical power in dBm
+# TX_POWER_MAX      - Maximum acceptable TX optical power in dBm
+# TEMPERATURE_MAX   - Maximum module temperature in °C before alert
 RX_POWER_MIN=-28.0
 RX_POWER_MAX=-8.0
 TX_POWER_MIN=0.5
 TX_POWER_MAX=4.0
 TEMPERATURE_MAX=85.0
+
+# ============================================================================
+# Laser Bias Current Thresholds (TX Bias)
+# ============================================================================
+# TX_BIAS_MIN       - Minimum TX bias current in mA (below = weak/failing laser)
+# TX_BIAS_MAX       - Maximum TX bias current in mA (above = laser aging/overheating)
+TX_BIAS_MIN=5.0
+TX_BIAS_MAX=90.0
+
+# ============================================================================
+# Supply Voltage Thresholds
+# ============================================================================
+# VOLTAGE_MIN       - Minimum supply voltage in volts (below = unstable power)
+# VOLTAGE_MAX       - Maximum supply voltage in volts (above = risk of damage)
+VOLTAGE_MIN=3.0
+VOLTAGE_MAX=3.6
diff --git a/README.md b/README.md
index 88aa232..a244887 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,8 @@ GPON_HOST=192.168.100.1
 GPON_USERNAME=leox
 GPON_PASSWORD=leolabs_7
 EXTERNAL_PORT=8080
+
+[...]
 ```
 
 ### 3. Start the container
diff --git a/config.py b/config.py
index f92b922..950b732 100644
--- a/config.py
+++ b/config.py
@@ -26,6 +26,10 @@ class Config:
         'tx_power_max': float(os.getenv('TX_POWER_MAX', 5.0)),
         'temperature_max': float(os.getenv('TEMPERATURE_MAX', 85.0)),
         'fec_errors_max': int(os.getenv('FEC_ERRORS_MAX', 1000)),
+        'tx_bias_min': float(os.getenv('TX_BIAS_MIN', 5.0)),
+        'tx_bias_max': float(os.getenv('TX_BIAS_MAX', 90.0)),
+        'voltage_min': float(os.getenv('VOLTAGE_MIN', 3.0)),
+        'voltage_max': float(os.getenv('VOLTAGE_MAX', 3.6)),
     }
     
     # Web Interface