plant_watering/
├── status/
│   ├── esp32/connected        # ESP32 connection status (retained)
│   ├── esp32/ip              # ESP32 IP address (retained)
│   ├── esp32/uptime          # System uptime in seconds
│   ├── esp32/version         # Firmware version (retained)
│   ├── esp32/rssi            # WiFi signal strength
│   ├── esp32/free_heap       # Free memory for diagnostics
│   └── esp32/restart_reason  # Last restart reason (retained)
├── pump/1/
│   ├── command               # Commands: ON/OFF/PULSE
│   ├── status                # Current status (retained)
│   ├── runtime               # Last run duration in seconds
│   ├── total_runtime         # Total runtime counter in seconds
│   ├── last_activated        # Timestamp of last activation
│   └── flow_rate             # If flow sensor added later
├── pump/2/
│   ├── command               # Commands: ON/OFF/PULSE
│   ├── status                # Current status (retained)
│   ├── runtime               # Last run duration in seconds
│   ├── total_runtime         # Total runtime counter in seconds
│   ├── last_activated        # Timestamp of last activation
│   └── flow_rate             # If flow sensor added later
├── sensor/1/
│   ├── moisture              # Current moisture reading (0-4095)
│   ├── moisture_percent      # Moisture as percentage
│   ├── last_watered          # Timestamp of last watering
│   ├── temperature           # Soil temperature if sensor supports
│   └── calibration/
│       ├── dry_value         # Calibration point for dry
│       └── wet_value         # Calibration point for wet
├── sensor/2/
│   ├── moisture              # Current moisture reading (0-4095)
│   ├── moisture_percent      # Moisture as percentage
│   ├── last_watered          # Timestamp of last watering
│   ├── temperature           # Soil temperature if sensor supports
│   └── calibration/
│       ├── dry_value         # Calibration point for dry
│       └── wet_value         # Calibration point for wet
├── settings/
│   ├── pump/1/
│   │   ├── moisture_threshold # Trigger threshold (0-100%)
│   │   ├── water_duration    # Watering duration in seconds
│   │   ├── min_interval      # Minimum hours between watering
│   │   ├── max_duration      # Safety maximum runtime
│   │   └── enabled           # Enable/disable pump
│   ├── pump/2/
│   │   ├── moisture_threshold # Trigger threshold (0-100%)
│   │   ├── water_duration    # Watering duration in seconds
│   │   ├── min_interval      # Minimum hours between watering
│   │   ├── max_duration      # Safety maximum runtime
│   │   └── enabled           # Enable/disable pump
│   └── system/
│       ├── report_interval   # How often to publish sensor data
│       ├── timezone          # For scheduling features
│       └── auto_mode         # Global auto-watering enable
├── alerts/
│   ├── low_moisture/1        # Zone 1 moisture too low
│   ├── low_moisture/2        # Zone 2 moisture too low
│   ├── pump_error/1          # Pump 1 malfunction
│   ├── pump_error/2          # Pump 2 malfunction
│   ├── sensor_error/1        # Sensor 1 reading issues
│   ├── sensor_error/2        # Sensor 2 reading issues
│   └── water_tank_low        # If tank sensor added
└── commands/
    ├── calibrate/sensor/1    # Trigger calibration mode
    ├── calibrate/sensor/2    # Trigger calibration mode
    ├── restart               # Restart ESP32
    ├── factory_reset         # Clear all settings
    └── ota/url              # Trigger OTA from URL


Additional considerations:

Timestamps: Use ISO 8601 format (e.g., "2024-01-15T14:30:00Z") for consistency
Retained messages: Mark critical status messages as retained (as you've done)
QoS levels:

QoS 0 for frequent sensor readings
QoS 1 for commands and state changes
QoS 2 for critical alerts (if needed)


JSON payloads: Consider using JSON for complex data:

// plant_watering/status/esp32/info
{
  "version": "2.0.0",
  "uptime": 3600,
  "free_heap": 45632,
  "rssi": -65,
  "ip": "192.168.1.42"
}

Home Assistant Discovery: Add discovery topics if planning HA integration:

homeassistant/sensor/plant_watering_moisture_1/config
homeassistant/switch/plant_watering_pump_1/config