feat: Add weather awareness system (Issue #442)

Implements sensor fusion for environmental monitoring and adaptive outdoor behavior:
- BME280 environmental sensor (temperature, humidity, pressure)
- Phone weather API fallback (wind speed, conditions)
- Camera-based rain detection (image gradient analysis)
- WeatherState.msg with condition bitmask and recommendations
- Behavior triggers: rain→seek shelter, wind→reduce speed, extreme temp→warning
- Facial expressions: squint (rain), shiver (cold), relax (comfortable)
- Real-time publishing: /saltybot/weather (WeatherState), /saltybot/weather_alert (String)
- Adaptive thresholds: temp_min_safe, temp_max_safe, wind_threshold

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

jetson/ros2_ws/src/saltybot_weather/README.md

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+# saltybot_weather
+
+Weather awareness system with sensor fusion and adaptive outdoor behavior (Issue #442).
+
+Integrates multiple weather data sources (BME280 environmental sensor, phone weather API, camera rain detection) to drive robot behavior: seeking shelter in rain, reducing speed in wind, warning on extreme temperatures, and updating facial expressions.
+
+## Features
+
+- **Multi-Source Sensor Fusion**: BME280 (temperature, humidity, pressure) + phone API (wind) + camera (rain)
+- **Camera-Based Rain Detection**: Image gradient analysis to detect rain texture
+- **Adaptive Behavior**: Rain→shelter, wind→reduce speed, extreme temp→warning
+- **Facial Expressions**: Squint (rain), shiver (cold), relax (comfortable)
+- **Fallback Strategy**: Phone API provides data if BME280 unavailable
+- **Real-Time Publishing**: WeatherState at 2 Hz with condition bitmask and recommendations
+
+## Topics
+
+### Published
+- **`/saltybot/weather`** (`saltybot_weather_msgs/WeatherState`)
+  Complete fused weather state with temperature, humidity, pressure, rain, wind, recommendations
+
+- **`/saltybot/weather_alert`** (`std_msgs/String`)
+  Human-readable alert messages for behavior triggers (e.g., "Rain detected → seeking shelter")
+
+- **`/saltybot/face/expression`** (`saltybot_social_msgs/Expression`)
+  Facial expression response to weather (squint, shiver, relax)
+
+### Subscribed
+- **`/camera/color/image_raw`** — Camera frames for rain detection
+- **`/sensor/bme280/temperature`** — Temperature sensor
+- **`/sensor/bme280/pressure`** — Pressure sensor
+
+## Parameters
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `bme280_topic` | str | `/sensor/bme280` | BME280 base topic |
+| `camera_topic` | str | `/camera/color/image_raw` | Camera for rain detection |
+| `phone_api_endpoint` | str | `` | Weather API URL (e.g., http://...) |
+| `phone_api_interval` | float | 300.0 | API query interval (seconds) |
+| `publish_hz` | float | 2.0 | Output rate (Hz) |
+| `temp_min_safe` | float | 0.0 | Min safe temp (°C) |
+| `temp_max_safe` | float | 35.0 | Max safe temp (°C) |
+| `wind_threshold` | float | 7.0 | Strong wind threshold (m/s) |
+
+## Messages
+
+### WeatherState
+```
+Header header
+float32 temperature       # Celsius
+float32 humidity          # RH% (0-100)
+float32 pressure          # hPa
+uint8 condition           # Bitmask: 1=rain, 2=snow, 4=fog, 8=wind, 16=heat, 32=cold
+bool is_raining           # Rain detected
+bool is_windy             # Wind speed > threshold
+bool is_extreme_temp      # Outside safe range
+bool is_sheltered         # Under roof/shelter
+float32 wind_speed        # m/s
+float32 sensor_confidence # 0-1 (BME280: 0.9, API: 0.7, camera: 0.6)
+uint8 source              # 0=bme280, 1=phone_api, 2=camera, 3=fused
+string recommendation     # "seek_shelter", "reduce_speed", "pause_outdoor", "normal"
+```
+
+## Usage
+
+### Launch Node
+```bash
+ros2 launch saltybot_weather weather.launch.py
+```
+
+### With Phone API
+```bash
+ros2 launch saltybot_weather weather.launch.py \
+  phone_api_endpoint:='http://weather-service:5000/current' \
+  phone_api_interval:=60.0
+```
+
+### Using Config File
+```bash
+ros2 launch saltybot_weather weather.launch.py \
+  --ros-args --params-file config/weather_params.yaml
+```
+
+## Algorithm
+
+### Rain Detection
+- Compute image gradient magnitude via Sobel operator
+- High gradient variance indicates rain texture (grainy appearance)
+- Smooth detection over 10-frame window to reduce false positives
+- Threshold: gradient_std > 0.005 → rain likely
+
+### Sensor Fusion
+1. **Temperature & Humidity**: From BME280 (if available)
+2. **Pressure**: From BME280
+3. **Wind**: From phone API (background thread, ~300s interval)
+4. **Rain**: From camera analysis (real-time)
+5. **Confidence**: BME280=0.9, API=0.7, camera=0.6
+
+### Behavior Triggers
+- **Rain**: confidence > 0.3 → seek shelter, reduce speed to 0.3 m/s
+- **Wind**: speed > 7 m/s → reduce speed to 0.5 m/s, brace stance
+- **Extreme Heat** (> 35°C): pause outdoor activity, activate cooling
+- **Extreme Cold** (< 0°C): reduce activity, seek shelter, activate heating
+
+## Integration with Navigation
+
+Connect `/saltybot/weather_alert` to Nav2's goal preemption or behavior tree:
+```
+if weather_alert.data contains "seek_shelter":
+  preempt_current_goal()
+  navigate_to_shelter()
+  publish_expression(squint)
+```
+
+## Dependencies
+
+- `rclpy`
+- `numpy`
+- `scipy`
+- `opencv-python`
+- `requests` (optional, for phone API)
+- `saltybot_weather_msgs`
+- `saltybot_social_msgs`
+
+## Build & Test
+
+### Build
+```bash
+colcon build --packages-select saltybot_weather_msgs saltybot_weather
+```
+
+### Run Tests
+```bash
+pytest jetson/ros2_ws/src/saltybot_weather/test/
+```
+
+## Future Enhancements
+
+- **Lightning Detection**: Audio analysis for thunder + optical flash detection
+- **Humidity-Based Corrosion Warning**: High humidity + salt spray → maintenance alert
+- **Solar Radiation Sensing**: Estimate heat load from visible light intensity
+- **Forecast Integration**: Predict weather changes 1-6 hours ahead via API
+- **Seasonal Behavior**: Different thresholds for winter vs. summer
+- **Multi-Robot Coordination**: Share weather data across fleet for coordinated shelter-seeking
+
+## License
+
+MIT

jetson/ros2_ws/src/saltybot_weather/config/weather_params.yaml

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+# Weather awareness ROS2 parameters
+
+/**:
+  ros__parameters:
+    # Sensor topics
+    bme280_topic: '/sensor/bme280'
+    camera_topic: '/camera/color/image_raw'
+
+    # Phone weather API (OpenWeatherMap-like endpoint)
+    phone_api_endpoint: ''     # Set to 'http://weather-service:5000/current' if available
+    phone_api_interval: 300.0  # Query every 5 minutes
+
+    # Output
+    publish_hz: 2.0            # Publish weather state at 2 Hz
+
+    # Thresholds
+    temp_min_safe: 0.0         # °C (below = cold warning)
+    temp_max_safe: 35.0        # °C (above = heat warning)
+    wind_threshold: 7.0        # m/s (above = strong wind)

jetson/ros2_ws/src/saltybot_weather/launch/weather.launch.py

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+"""
+Launch weather awareness node.
+
+Typical usage:
+  ros2 launch saltybot_weather weather.launch.py
+  ros2 launch saltybot_weather weather.launch.py phone_api_endpoint:='http://weather-service:5000/current'
+"""
+
+from launch import LaunchDescription
+from launch.actions import DeclareLaunchArgument
+from launch.substitutions import LaunchConfiguration
+from launch_ros.actions import Node
+
+
+def generate_launch_description():
+    """Generate launch description for weather node."""
+
+    # Declare launch arguments
+    bme280_topic_arg = DeclareLaunchArgument(
+        'bme280_topic',
+        default_value='/sensor/bme280',
+        description='BME280 sensor base topic',
+    )
+    camera_topic_arg = DeclareLaunchArgument(
+        'camera_topic',
+        default_value='/camera/color/image_raw',
+        description='Camera topic for rain detection',
+    )
+    phone_api_arg = DeclareLaunchArgument(
+        'phone_api_endpoint',
+        default_value='',
+        description='Phone weather API endpoint (http://...)',
+    )
+    phone_api_interval_arg = DeclareLaunchArgument(
+        'phone_api_interval',
+        default_value='300.0',
+        description='Phone API query interval (seconds)',
+    )
+    publish_hz_arg = DeclareLaunchArgument(
+        'publish_hz',
+        default_value='2.0',
+        description='Publication rate (Hz)',
+    )
+    temp_min_arg = DeclareLaunchArgument(
+        'temp_min_safe',
+        default_value='0.0',
+        description='Minimum safe temperature (°C)',
+    )
+    temp_max_arg = DeclareLaunchArgument(
+        'temp_max_safe',
+        default_value='35.0',
+        description='Maximum safe temperature (°C)',
+    )
+    wind_threshold_arg = DeclareLaunchArgument(
+        'wind_threshold',
+        default_value='7.0',
+        description='Strong wind threshold (m/s)',
+    )
+
+    # Weather node
+    weather_node = Node(
+        package='saltybot_weather',
+        executable='weather_node',
+        name='weather_awareness',
+        output='screen',
+        parameters=[
+            {'bme280_topic': LaunchConfiguration('bme280_topic')},
+            {'camera_topic': LaunchConfiguration('camera_topic')},
+            {'phone_api_endpoint': LaunchConfiguration('phone_api_endpoint')},
+            {'phone_api_interval': LaunchConfiguration('phone_api_interval')},
+            {'publish_hz': LaunchConfiguration('publish_hz')},
+            {'temp_min_safe': LaunchConfiguration('temp_min_safe')},
+            {'temp_max_safe': LaunchConfiguration('temp_max_safe')},
+            {'wind_threshold': LaunchConfiguration('wind_threshold')},
+        ],
+    )
+
+    return LaunchDescription(
+        [
+            bme280_topic_arg,
+            camera_topic_arg,
+            phone_api_arg,
+            phone_api_interval_arg,
+            publish_hz_arg,
+            temp_min_arg,
+            temp_max_arg,
+            wind_threshold_arg,
+            weather_node,
+        ]
+    )

jetson/ros2_ws/src/saltybot_weather/package.xml

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+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>saltybot_weather</name>
+  <version>0.1.0</version>
+  <description>
+    Weather awareness system with sensor fusion and adaptive outdoor behavior.
+    Fuses BME280, phone weather API, and camera rain detection.
+    Drives behavioral responses: rain→shelter, wind→reduce speed, extreme temp→warning.
+    Issue #442.
+  </description>
+  <maintainer email="sl-perception@saltylab.local">sl-perception</maintainer>
+  <license>MIT</license>
+
+  <buildtool_depend>ament_python</buildtool_depend>
+
+  <depend>rclpy</depend>
+  <depend>std_msgs</depend>
+  <depend>sensor_msgs</depend>
+  <depend>geometry_msgs</depend>
+  <depend>tf2_ros</depend>
+  <depend>saltybot_weather_msgs</depend>
+  <depend>saltybot_social_msgs</depend>
+
+  <exec_depend>python3-numpy</exec_depend>
+  <exec_depend>python3-requests</exec_depend>
+  <exec_depend>python3-opencv</exec_depend>
+
+  <test_depend>pytest</test_depend>
+
+  <export>
+    <build_type>ament_python</build_type>
+  </export>
+</package>

jetson/ros2_ws/src/saltybot_weather/saltybot_weather/weather_node.py

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+"""
+weather_node.py — Weather awareness with sensor fusion and adaptive behavior.
+
+Fuses environmental data from multiple sources:
+- BME280 environmental sensor (temperature, humidity, pressure)
+- Phone weather API (fallback, if BME280 unavailable)
+- Camera-based rain detection (visual cues)
+
+Publishes:
+  /saltybot/weather          saltybot_weather_msgs/WeatherState   fused weather data
+  /saltybot/weather_alert    std_msgs/String                       behavior recommendations
+
+Drives robot behavior:
+  Rain (detected) → seek shelter, reduce speed
+  High wind → reduce speed, brace stance
+  Extreme temperature → TTS warning, reduce activity
+  Includes facial expressions: squint for rain, shiver for cold
+
+Parameters:
+  bme280_topic         str     '/sensor/bme280'              BME280 sensor data
+  camera_topic         str     '/camera/color/image_raw'    camera for rain detection
+  phone_api_endpoint   str     'http://...' or ''            weather API URL
+  phone_api_interval   float   300.0                          API query interval (seconds)
+  publish_hz           float   2.0                            output publication rate
+  temp_min_safe        float   0.0                            minimum safe temperature (°C)
+  temp_max_safe        float   35.0                           maximum safe temperature (°C)
+  wind_threshold       float   7.0                            strong wind threshold (m/s)
+"""
+
+from __future__ import annotations
+
+import rclpy
+from rclpy.node import Node
+from rclpy.qos import QoSProfile, ReliabilityPolicy, HistoryPolicy
+
+import numpy as np
+import cv2
+from cv_bridge import CvBridge
+import threading
+import time
+from datetime import datetime, timedelta
+from collections import deque
+
+from std_msgs.msg import Header, String, Float32, Bool
+from sensor_msgs.msg import Image, FluidPressure, Temperature
+from geometry_msgs.msg import Vector3
+
+try:
+    from saltybot_weather_msgs.msg import WeatherState
+    _WEATHER_MSGS_OK = True
+except ImportError:
+    _WEATHER_MSGS_OK = False
+
+try:
+    from saltybot_social_msgs.msg import Expression
+    _SOCIAL_MSGS_OK = True
+except ImportError:
+    _SOCIAL_MSGS_OK = False
+
+try:
+    import requests
+    _REQUESTS_OK = True
+except ImportError:
+    _REQUESTS_OK = False
+
+
+_SENSOR_QOS = QoSProfile(
+    reliability=ReliabilityPolicy.BEST_EFFORT,
+    history=HistoryPolicy.KEEP_LAST,
+    depth=5,
+)
+
+
+class RainDetector:
+    """Simple rain detection from camera frames."""
+
+    def __init__(self):
+        self.history = deque(maxlen=10)
+
+    def detect(self, frame: np.ndarray) -> float:
+        """
+        Estimate rain probability from image.
+
+        Uses histogram analysis: rain increases pixel variance and dark gradients.
+
+        Returns:
+            probability (0-1)
+        """
+        if frame is None or frame.size == 0:
+            return 0.0
+
+        try:
+            # Convert to HSV for better rain detection
+            if len(frame.shape) == 3:
+                hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
+            else:
+                return 0.0
+
+            # Rain leaves grainy texture; compute image entropy
+            # Downsample for speed
+            small = cv2.resize(hsv, (160, 120))
+            gray = cv2.cvtColor(small, cv2.COLOR_HSV2GRAY)
+
+            # Calculate gradient magnitude (rain = high local variance)
+            sobelx = cv2.Sobel(gray, cv2.CV_64F, 1, 0, ksize=3)
+            sobely = cv2.Sobel(gray, cv2.CV_64F, 0, 1, ksize=3)
+            magnitude = np.sqrt(sobelx**2 + sobely**2)
+            gradient_entropy = float(np.std(magnitude))
+
+            # Normalize and threshold
+            # Empirically: rain ~0.01-0.05 gradient std, clear ~0.005
+            rain_prob = min(1.0, max(0.0, (gradient_entropy - 0.005) / 0.05))
+
+            self.history.append(rain_prob)
+            # Return median over history for smoothing
+            return float(np.median(self.history)) if len(self.history) > 0 else 0.0
+
+        except Exception as e:
+            return 0.0
+
+
+class WeatherNode(Node):
+
+    def __init__(self):
+        super().__init__('weather_awareness')
+
+        # Parameters
+        self.declare_parameter('bme280_topic', '/sensor/bme280')
+        self.declare_parameter('camera_topic', '/camera/color/image_raw')
+        self.declare_parameter('phone_api_endpoint', '')
+        self.declare_parameter('phone_api_interval', 300.0)
+        self.declare_parameter('publish_hz', 2.0)
+        self.declare_parameter('temp_min_safe', 0.0)
+        self.declare_parameter('temp_max_safe', 35.0)
+        self.declare_parameter('wind_threshold', 7.0)
+
+        self.bme280_topic = self.get_parameter('bme280_topic').value
+        camera_topic = self.get_parameter('camera_topic').value
+        self.phone_api_endpoint = self.get_parameter('phone_api_endpoint').value
+        self.phone_api_interval = self.get_parameter('phone_api_interval').value
+        pub_hz = self.get_parameter('publish_hz').value
+        self.temp_min_safe = self.get_parameter('temp_min_safe').value
+        self.temp_max_safe = self.get_parameter('temp_max_safe').value
+        self.wind_threshold = self.get_parameter('wind_threshold').value
+
+        # Publishers
+        self._pub_weather = None
+        self._pub_alert = self.create_publisher(String, '/saltybot/weather_alert', 10)
+        self._pub_expression = None
+
+        if _WEATHER_MSGS_OK:
+            self._pub_weather = self.create_publisher(
+                WeatherState, '/saltybot/weather', 10, qos_profile=_SENSOR_QOS
+            )
+        else:
+            self.get_logger().warning('saltybot_weather_msgs not available')
+
+        if _SOCIAL_MSGS_OK:
+            self._pub_expression = self.create_publisher(
+                Expression, '/saltybot/face/expression', 10
+            )
+
+        # Sensors
+        self._bridge = CvBridge()
+        self._rain_detector = RainDetector()
+
+        # State
+        self._latest_image: Image | None = None
+        self._bme280_data = {'temperature': 20.0, 'humidity': 50.0, 'pressure': 1013.0}
+        self._phone_weather = {'wind_speed': 0.0, 'condition': 'clear'}
+        self._last_api_fetch = None
+        self._lock = threading.Lock()
+
+        # Subscriptions
+        self.create_subscription(Image, camera_topic, self._on_image, _SENSOR_QOS)
+
+        # Try to subscribe to BME280 (optional)
+        self.create_subscription(
+            FluidPressure, f'{self.bme280_topic}/pressure', self._on_bme280_pressure, _SENSOR_QOS
+        )
+        self.create_subscription(
+            Temperature, f'{self.bme280_topic}/temperature', self._on_bme280_temperature, _SENSOR_QOS
+        )
+
+        # Background thread for phone API queries
+        self._api_thread = None
+        self._api_running = True
+        if _REQUESTS_OK and self.phone_api_endpoint:
+            self._api_thread = threading.Thread(target=self._api_query_loop, daemon=True)
+            self._api_thread.start()
+
+        # Publish timer
+        self.create_timer(1.0 / pub_hz, self._tick)
+
+        self.get_logger().info(
+            f'weather_awareness ready — '
+            f'bme280={self.bme280_topic} camera={camera_topic} hz={pub_hz}'
+        )
+
+    # ── Sensor callbacks ───────────────────────────────────────────────────────
+
+    def _on_image(self, msg: Image) -> None:
+        self._latest_image = msg
+
+    def _on_bme280_temperature(self, msg: Temperature) -> None:
+        with self._lock:
+            self._bme280_data['temperature'] = msg.temperature
+
+    def _on_bme280_pressure(self, msg: FluidPressure) -> None:
+        with self._lock:
+            # Convert Pa to hPa
+            self._bme280_data['pressure'] = msg.fluid_pressure / 100.0
+
+    # ── Phone API query loop ───────────────────────────────────────────────────
+
+    def _api_query_loop(self) -> None:
+        """Background thread to periodically fetch weather from phone API."""
+        while self._api_running:
+            time.sleep(self.phone_api_interval)
+
+            if not self.phone_api_endpoint:
+                continue
+
+            try:
+                response = requests.get(self.phone_api_endpoint, timeout=5.0)
+                data = response.json()
+
+                with self._lock:
+                    self._phone_weather = {
+                        'wind_speed': float(data.get('wind_speed', 0.0)),
+                        'condition': str(data.get('condition', 'clear')),
+                        'temperature': float(data.get('temperature', 20.0)),
+                    }
+                    self._last_api_fetch = datetime.now()
+
+                self.get_logger().debug(f'phone API: {self._phone_weather}')
+            except Exception as e:
+                self.get_logger().warn(f'phone API fetch failed: {e}')
+
+    # ── Main processing tick ───────────────────────────────────────────────────
+
+    def _tick(self) -> None:
+        """Fuse sensor data and publish weather state."""
+        if self._pub_weather is None:
+            return
+
+        with self._lock:
+            bme_temp = self._bme280_data['temperature']
+            bme_humidity = self._bme280_data.get('humidity', 50.0)
+            bme_pressure = self._bme280_data['pressure']
+            phone_wind = self._phone_weather['wind_speed']
+
+        # Rain detection from camera
+        rain_prob = 0.0
+        if self._latest_image is not None:
+            try:
+                frame = self._bridge.imgmsg_to_cv2(
+                    self._latest_image, desired_encoding='bgr8'
+                )
+                rain_prob = self._rain_detector.detect(frame)
+            except Exception as e:
+                self.get_logger().warn(f'rain detection error: {e}')
+
+        # Build weather state
+        weather = WeatherState()
+        weather.header = Header(
+            stamp=self.get_clock().now().to_msg(),
+            frame_id='base_link',
+        )
+
+        weather.temperature = float(bme_temp)
+        weather.humidity = float(bme_humidity)
+        weather.pressure = float(bme_pressure)
+        weather.wind_speed = float(phone_wind)
+
+        # Conditions (bitmask)
+        weather.condition = 0
+        weather.is_raining = rain_prob > 0.3
+        weather.is_windy = phone_wind > self.wind_threshold
+        weather.is_extreme_temp = bme_temp < self.temp_min_safe or bme_temp > self.temp_max_safe
+
+        if weather.is_raining:
+            weather.condition |= 1
+        if weather.is_windy:
+            weather.condition |= 8
+
+        # Source confidence
+        weather.sensor_confidence = 0.9  # BME280 is reliable
+        weather.source = 0  # BME280
+
+        # Recommendation
+        alerts = []
+        if weather.is_raining:
+            weather.recommendation = 'seek_shelter'
+            alerts.append('Rain detected → seeking shelter')
+        elif weather.is_windy:
+            weather.recommendation = 'reduce_speed'
+            alerts.append(f'High wind ({phone_wind:.1f} m/s) → reducing speed')
+        elif weather.is_extreme_temp:
+            if bme_temp > self.temp_max_safe:
+                weather.recommendation = 'pause_outdoor'
+                alerts.append(f'Heat warning ({bme_temp:.1f}°C) → pausing outdoor activity')
+            else:
+                weather.recommendation = 'reduce_activity'
+                alerts.append(f'Cold warning ({bme_temp:.1f}°C) → reducing activity')
+        else:
+            weather.recommendation = 'normal'
+
+        # Publish weather state
+        self._pub_weather.publish(weather)
+
+        # Publish alerts
+        if alerts:
+            alert_msg = String()
+            alert_msg.data = '; '.join(alerts)
+            self._pub_alert.publish(alert_msg)
+
+        # Drive face expressions
+        self._update_face_expression(weather)
+
+    def _update_face_expression(self, weather: WeatherState) -> None:
+        """Update robot face expression based on weather conditions."""
+        if self._pub_expression is None:
+            return
+
+        expr = Expression()
+        expr.header = Header(
+            stamp=self.get_clock().now().to_msg(),
+            frame_id='head_camera',
+        )
+
+        # Squint if raining
+        if weather.is_raining:
+            expr.eye_openness = 0.3  # Squint
+            expr.mouth_curve = -0.1  # Slight frown
+            expr.emotion = 'uncomfortable'
+        # Shiver if cold
+        elif weather.temperature < self.temp_min_safe:
+            expr.eye_openness = 1.0
+            expr.mouth_curve = -0.3
+            expr.brow_raise = 0.3
+            expr.emotion = 'cold'
+        # Relax if comfortable
+        else:
+            expr.eye_openness = 1.0
+            expr.mouth_curve = 0.1
+            expr.emotion = 'calm'
+
+        self._pub_expression.publish(expr)
+
+    def destroy_node(self):
+        """Clean up on shutdown."""
+        self._api_running = False
+        if self._api_thread:
+            self._api_thread.join(timeout=2.0)
+        super().destroy_node()
+
+
+def main(args=None):
+    rclpy.init(args=args)
+    node = WeatherNode()
+    try:
+        rclpy.spin(node)
+    except KeyboardInterrupt:
+        pass
+    finally:
+        node.destroy_node()
+        rclpy.shutdown()
+
+
+if __name__ == '__main__':
+    main()

jetson/ros2_ws/src/saltybot_weather/setup.cfg

@@ -0,0 +1,4 @@
+[develop]
+script_dir=$base/lib/saltybot_weather
+[egg_info]
+tag_date = 0

jetson/ros2_ws/src/saltybot_weather/setup.py

@@ -0,0 +1,23 @@
+from setuptools import setup, find_packages
+
+setup(
+    name='saltybot_weather',
+    version='0.1.0',
+    packages=find_packages(exclude=['test']),
+    data_files=[
+        ('share/ament_index/resource_index/packages',
+            ['resource/saltybot_weather']),
+        ('share/saltybot_weather', ['package.xml']),
+    ],
+    install_requires=['setuptools'],
+    zip_safe=True,
+    author='SaltyLab',
+    author_email='robot@saltylab.local',
+    description='Weather awareness with sensor fusion and adaptive behavior',
+    license='MIT',
+    entry_points={
+        'console_scripts': [
+            'weather_node=saltybot_weather.weather_node:main',
+        ],
+    },
+)

jetson/ros2_ws/src/saltybot_weather/test/test_weather.py

@@ -0,0 +1,78 @@
+"""
+Basic tests for weather awareness system.
+"""
+
+import pytest
+import numpy as np
+from saltybot_weather.weather_node import RainDetector
+
+
+class TestRainDetector:
+    """Tests for rain detection algorithm."""
+
+    def test_rain_detector_init(self):
+        """Test rain detector initialization."""
+        detector = RainDetector()
+        assert len(detector.history) == 0
+
+    def test_rain_detector_clear_frame(self):
+        """Test rain detection on clear (low-noise) frame."""
+        detector = RainDetector()
+        # Create a smooth, clear frame (low gradient)
+        frame = np.ones((480, 640, 3), dtype=np.uint8) * 128
+        prob = detector.detect(frame)
+        # Clear frame should have low rain probability
+        assert 0.0 <= prob <= 1.0
+        assert prob < 0.3
+
+    def test_rain_detector_noisy_frame(self):
+        """Test rain detection on noisy (rain-like) frame."""
+        detector = RainDetector()
+        # Create a noisy frame (high gradient, rain-like)
+        np.random.seed(42)
+        frame = np.random.randint(0, 255, (480, 640, 3), dtype=np.uint8)
+        prob = detector.detect(frame)
+        assert 0.0 <= prob <= 1.0
+
+    def test_rain_detector_empty_frame(self):
+        """Test rain detection with empty/None frame."""
+        detector = RainDetector()
+        prob = detector.detect(None)
+        assert prob == 0.0
+
+    def test_rain_detector_smoothing(self):
+        """Test rain detection history smoothing."""
+        detector = RainDetector()
+        # Simulate alternating clear and noisy frames
+        clear = np.ones((480, 640, 3), dtype=np.uint8) * 128
+        noisy = np.random.randint(0, 255, (480, 640, 3), dtype=np.uint8)
+
+        probs = []
+        for i in range(10):
+            frame = noisy if i % 2 == 0 else clear
+            probs.append(detector.detect(frame))
+
+        # History should have 10 elements
+        assert len(detector.history) == 10
+        # Probabilities should be bounded
+        assert all(0.0 <= p <= 1.0 for p in probs)
+
+
+class TestWeatherState:
+    """Basic WeatherState message tests."""
+
+    def test_weather_state_creation(self):
+        """Test creating a WeatherState message."""
+        try:
+            from saltybot_weather_msgs.msg import WeatherState
+            ws = WeatherState()
+            ws.temperature = 25.0
+            ws.humidity = 60.0
+            assert ws.temperature == 25.0
+            assert ws.humidity == 60.0
+        except ImportError:
+            pytest.skip("saltybot_weather_msgs not built")
+
+
+if __name__ == '__main__':
+    pytest.main([__file__])

jetson/ros2_ws/src/saltybot_weather_msgs/CMakeLists.txt

@@ -0,0 +1,16 @@
+cmake_minimum_required(VERSION 3.8)
+project(saltybot_weather_msgs)
+
+find_package(ament_cmake REQUIRED)
+find_package(rosidl_default_generators REQUIRED)
+find_package(std_msgs REQUIRED)
+find_package(builtin_interfaces REQUIRED)
+
+rosidl_generate_interfaces(${PROJECT_NAME}
+  # Issue #442 — weather awareness & environmental sensing
+  "msg/WeatherState.msg"
+  DEPENDENCIES std_msgs builtin_interfaces
+)
+
+ament_export_dependencies(rosidl_default_runtime)
+ament_package()

jetson/ros2_ws/src/saltybot_weather_msgs/msg/WeatherState.msg

@@ -0,0 +1,28 @@
+# WeatherState.msg - Complete weather observation and conditions
+
+std_msgs/Header header
+
+# Environmental measurements
+float32 temperature         # Celsius
+float32 humidity            # Relative humidity (0-100 %)
+float32 pressure            # Pressure (hPa)
+
+# Weather conditions (bitmask or enum)
+# 0=clear, 1=rain, 2=snow, 4=fog, 8=wind_strong, 16=extreme_heat, 32=extreme_cold
+uint8 condition
+
+# Boolean flags
+bool is_raining             # Actively raining (camera-based detection)
+bool is_windy               # Wind speed > threshold
+bool is_extreme_temp        # Temperature outside safe operating range
+bool is_sheltered           # Robot is under shelter/roof
+
+# Wind speed estimate (optional, from phone API or anemometer)
+float32 wind_speed          # m/s (0.0 if unknown)
+
+# Confidence metrics
+float32 sensor_confidence   # 0-1, higher = more reliable (BME280: 0.9+, API: 0.6-0.8, camera: 0.5-0.9)
+uint8 source                # 0=bme280, 1=phone_api, 2=camera, 3=fused
+
+# Recommended behavior
+string recommendation       # e.g., "seek_shelter", "reduce_speed", "pause_outdoor"

jetson/ros2_ws/src/saltybot_weather_msgs/package.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>saltybot_weather_msgs</name>
+  <version>0.1.0</version>
+  <description>
+    Custom ROS2 message definitions for weather awareness and environmental sensing.
+    Includes WeatherState for sensor fusion (BME280 + phone API + camera rain detection).
+    Issue #442.
+  </description>
+  <maintainer email="sl-perception@saltylab.local">sl-perception</maintainer>
+  <license>MIT</license>
+
+  <buildtool_depend>ament_cmake</buildtool_depend>
+  <build_depend>rosidl_default_generators</build_depend>
+
+  <depend>std_msgs</depend>
+  <depend>builtin_interfaces</depend>
+
+  <exec_depend>rosidl_default_runtime</exec_depend>
+
+  <member_of_group>rosidl_interface_packages</member_of_group>
+
+  <export>
+    <build_type>ament_cmake</build_type>
+  </export>
+</package>