feat: rosbridge WebSocket server for web UI (port 9090)

Adds rosbridge_suite to the Jetson stack so the browser dashboard can
subscribe to ROS2 topics via roslibjs over ws://jetson:9090.

docker-compose.yml
  New service: saltybot-rosbridge
  - Runs saltybot_bringup/launch/rosbridge.launch.py
  - network_mode: host → port 9090 directly reachable on Jetson LAN
  - Depends on saltybot-ros2, stm32-bridge, csi-cameras

saltybot_bringup/launch/rosbridge.launch.py
  - rosbridge_websocket node (port 9090, params from rosbridge_params.yaml)
  - 4× image_transport/republish nodes: compress CSI camera streams
    /camera/<name>/image_raw → /camera/<name>/image_raw/compressed (JPEG 75%)

saltybot_bringup/config/rosbridge_params.yaml
  Whitelisted topics:
    /map  /scan  /tf  /tf_static
    /saltybot/imu  /saltybot/balance_state
    /cmd_vel
    /person/*
    /camera/*/image_raw/compressed
  max_message_size: 10 MB (OccupancyGrid headroom)

saltybot_bringup/SENSORS.md
  Added rosbridge connection section with roslibjs snippet,
  topic reference table, bandwidth estimates, and throttle_rate tips.

saltybot_bringup/package.xml
  Added exec_depend: rosbridge_server, image_transport,
  image_transport_plugins (all already installed in Docker image).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

jetson/docker-compose.yml

@@ -166,6 +166,20 @@ services:
 
   # ── Surround vision — 360° bird's-eye view + Nav2 camera obstacle layer ─────
   saltybot-surround:
+
+  # ── rosbridge WebSocket server ────────────────────────────────────────────
+  # Serves ROS2 topics to the web dashboard (roslibjs) on ws://jetson:9090
+  #
+  # Topics exposed (whitelist in ros2_ws/src/saltybot_bringup/config/rosbridge_params.yaml):
+  #   /map  /scan  /tf  /tf_static  /saltybot/imu  /saltybot/balance_state
+  #   /cmd_vel  /person/*  /camera/*/image_raw/compressed
+  #
+  # Also runs image_transport/republish nodes to compress 4× CSI camera streams.
+  # Raw 640×480 YUYV → JPEG-compressed sensor_msgs/CompressedImage.
+  #
+  # Install (already in image): apt install ros-humble-rosbridge-server
+  #                                         ros-humble-image-transport-plugins
+  rosbridge:
     image: saltybot/ros2-humble:jetson-orin
     build:
       context: .
@@ -191,6 +205,29 @@ services:
           start_cameras:=false
           camera_height:=0.30
           publish_rate:=5.0
+
+    container_name: saltybot-rosbridge
+    restart: unless-stopped
+    runtime: nvidia
+    network_mode: host            # port 9090 is directly reachable on host
+    depends_on:
+      - saltybot-ros2             # needs /map, /tf published
+      - stm32-bridge              # needs /saltybot/imu, /saltybot/balance_state
+      - csi-cameras               # needs /camera/*/image_raw for compression
+    environment:
+      - ROS_DOMAIN_ID=42
+      - RMW_IMPLEMENTATION=rmw_cyclonedds_cpp
+    volumes:
+      - ./ros2_ws/src:/ros2_ws/src:rw
+      - ./config:/config:ro
+    # Port 9090 is accessible on all host interfaces via network_mode: host.
+    # To restrict to a specific interface, set host: "192.168.x.x" in
+    # rosbridge_params.yaml instead of using Docker port mappings.
+    command: >
+      bash -c "
+        source /opt/ros/humble/setup.bash &&
+        source /ros2_ws/install/local_setup.bash 2>/dev/null || true &&
+        ros2 launch saltybot_bringup rosbridge.launch.py
       "
 
   # ── Nav2 autonomous navigation stack ────────────────────────────────────────

jetson/ros2_ws/src/saltybot_bringup/SENSORS.md

@@ -4,6 +4,60 @@ ROS2 Humble | ROS_DOMAIN_ID=42 | DDS: CycloneDDS
 
 ---
 
+## rosbridge WebSocket (web dashboard)
+
+The web dashboard connects to ROS2 topics via rosbridge WebSocket on **port 9090**.
+
+```bash
+# Start rosbridge (and compressed camera republishers):
+ros2 launch saltybot_bringup rosbridge.launch.py
+
+# Or via docker-compose:
+docker compose up -d rosbridge
+```
+
+**Browser connection (roslibjs):**
+```javascript
+var ros = new ROSLIB.Ros({ url: 'ws://jetson.local:9090' });
+ros.on('connection', () => console.log('connected'));
+ros.on('error',      (e) => console.error('error', e));
+ros.on('close',      () => console.log('disconnected'));
+```
+
+**Whitelisted topics** (configured in `config/rosbridge_params.yaml`):
+
+| Topic | Type | Notes |
+|-------|------|-------|
+| `/map` | `nav_msgs/OccupancyGrid` | Use `throttle_rate: 5000` (0.2 Hz) |
+| `/scan` | `sensor_msgs/LaserScan` | 5.5 Hz, 1440 pts |
+| `/tf` | `tf2_msgs/TFMessage` | Use `throttle_rate: 100` (10 Hz) |
+| `/tf_static` | `tf2_msgs/TFMessage` | One-shot on connect |
+| `/saltybot/imu` | `sensor_msgs/Imu` | 50 Hz, pitch/roll/yaw |
+| `/saltybot/balance_state` | `std_msgs/String` | JSON balance controller state |
+| `/cmd_vel` | `geometry_msgs/Twist` | Subscribe to monitor Nav2 commands |
+| `/person/target` | (custom) | Person tracking target |
+| `/person/detections` | (custom) | Person detection results |
+| `/camera/front/image_raw/compressed` | `sensor_msgs/CompressedImage` | JPEG 75%, 640×480 |
+| `/camera/left/image_raw/compressed` | `sensor_msgs/CompressedImage` | JPEG 75%, 640×480 |
+| `/camera/rear/image_raw/compressed` | `sensor_msgs/CompressedImage` | JPEG 75%, 640×480 |
+| `/camera/right/image_raw/compressed` | `sensor_msgs/CompressedImage` | JPEG 75%, 640×480 |
+
+**Bandwidth tips:**
+- Raw 640×480 YUYV = ~900 KB/frame. rosbridge republishes JPEG-compressed ≈ 15–25 KB/frame.
+- Always use `throttle_rate` for cameras in roslibjs (e.g. `throttle_rate: 200` = max 5 fps).
+- `/map` is large (~100 KB); use `throttle_rate: 5000` or subscribe only on demand.
+
+**Verify connection:**
+```bash
+# Check WebSocket is listening
+ss -tlnp | grep 9090
+
+# List topics visible to rosbridge
+ros2 topic list | grep -E 'map|scan|imu|camera|person|cmd_vel'
+```
+
+---
+
 ## Build & Run
 
 ```bash

jetson/ros2_ws/src/saltybot_bringup/config/rosbridge_params.yaml

@@ -0,0 +1,66 @@
+# rosbridge_params.yaml — rosbridge_websocket server configuration
+#
+# WebSocket endpoint:  ws://<jetson-ip>:9090
+# Browser client lib:  roslibjs  (cdn.jsdelivr.net/npm/roslib)
+#
+# Topic whitelist limits bandwidth and prevents unintended exposure.
+# Glob patterns follow Python fnmatch: * matches everything (incl. /).
+#
+# Bandwidth budget (worst case, all subscriptions active):
+#   /map           ~100 KB/update × 0.2 Hz = ~20 KB/s
+#   /scan          ~5 KB/scan    × 5.5 Hz = ~28 KB/s
+#   /saltybot/imu  ~0.2 KB/msg   × 50 Hz  = ~10 KB/s
+#   /tf            ~1 KB/msg     × 10 Hz  = ~10 KB/s
+#   4× cameras     ~20 KB/frame  × 5 Hz   = ~400 KB/s  (JPEG quality 75)
+#   ─────────────────────────────────────────────────────
+#   Total                                   ~470 KB/s ≈ 3.8 Mbps
+#
+# Use throttle_rate in roslibjs subscribe() calls to cap per-topic rates:
+#   viewer.subscribe({ topic: '/map', throttle_rate: 5000 })  // 0.2 Hz
+
+rosbridge_websocket:
+  ros__parameters:
+    # ── Network ──────────────────────────────────────────────────────────────
+    port: 9090
+    host: "0.0.0.0"          # bind all interfaces (Jetson LAN + USB-C)
+    address: ""
+
+    # ── Authentication ────────────────────────────────────────────────────────
+    authenticate: false       # no auth on local network; enable if exposed
+
+    # ── Message size ──────────────────────────────────────────────────────────
+    # OccupancyGrid /map can exceed 1 MB for large environments.
+    max_message_size: 10000000   # 10 MB
+
+    # ── Topic/service/param whitelists ────────────────────────────────────────
+    # JSON-encoded glob list.  "*" in a glob matches any chars including "/".
+    # Only topics matching at least one pattern are accessible to clients.
+    topics_glob: >-
+      ["/map",
+       "/person/target",
+       "/person/detections",
+       "/camera/*/image_raw/compressed",
+       "/scan",
+       "/cmd_vel",
+       "/saltybot/imu",
+       "/saltybot/balance_state",
+       "/tf",
+       "/tf_static"]
+
+    services_glob: "[]"       # no service calls via WebSocket
+    params_glob:   "[]"       # no parameter access via WebSocket
+
+    # ── Connection management ─────────────────────────────────────────────────
+    # Time (s) before dropping a client that stops responding.
+    unregister_timeout: 10.0
+
+    # Fragment timeout: max seconds to wait for all fragments of a large message.
+    fragment_timeout: 600
+
+    # Delay between consecutive outgoing messages (ms). 0 = unlimited.
+    # Set > 0 (e.g. 10) if browser JS event loop is overwhelmed.
+    delay_between_messages: 0
+
+    # ── Logging ───────────────────────────────────────────────────────────────
+    # Set to true to log every publish/subscribe call (verbose, dev only).
+    bson_only_mode: false

jetson/ros2_ws/src/saltybot_bringup/launch/rosbridge.launch.py

@@ -0,0 +1,97 @@
+"""
+rosbridge.launch.py — rosbridge WebSocket server + compressed image transport
+
+Starts two things:
+  1. rosbridge_websocket — WebSocket server on port 9090 (roslibjs-compatible)
+  2. image_transport/republish × 4 — compresses each CSI camera's raw stream
+     /camera/<name>/image_raw  →  /camera/<name>/image_raw/compressed
+
+Prerequisites (already installed in saltybot/ros2-humble:jetson-orin):
+  apt install ros-humble-rosbridge-server
+  apt install ros-humble-image-transport-plugins   # supplies compressed plugin
+
+Browser connection:
+  var ros = new ROSLIB.Ros({ url: 'ws://<jetson-ip>:9090' });
+
+Topic whitelist is configured in config/rosbridge_params.yaml.
+
+Bandwidth tips:
+  - Subscribe to /camera/<name>/image_raw/compressed, not raw images.
+  - Use throttle_rate in ROSLIB.Topic to cap camera update rate:
+      new ROSLIB.Topic({ ... messageType: 'sensor_msgs/CompressedImage',
+                         throttle_rate: 200 })  // max 5 fps per camera
+  - Subscribe to /map with throttle_rate: 5000 (0.2 Hz is enough for display).
+
+Usage:
+  ros2 launch saltybot_bringup rosbridge.launch.py
+
+Verify:
+  ros2 topic echo /rosbridge_websocket/status
+  # In browser console:
+  #   var ros = new ROSLIB.Ros({ url: 'ws://jetson.local:9090' });
+  #   ros.on('connection', () => console.log('connected'));
+"""
+
+import os
+from launch import LaunchDescription
+from launch_ros.actions import Node
+from ament_index_python.packages import get_package_share_directory
+
+
+# Camera names matching saltybot_cameras/launch/csi_cameras.launch.py
+# Topics: /camera/<name>/image_raw  (published by v4l2_camera_node)
+_CAMERAS = ['front', 'left', 'rear', 'right']
+
+# JPEG quality for compressed output (0–100).
+# 75 = good quality/size trade-off at 640×480: ~15–25 KB/frame.
+# Lower to 50 for tighter bandwidth budgets; raise to 90 for inspection use.
+_JPEG_QUALITY = 75
+
+
+def generate_launch_description():
+    pkg_share = get_package_share_directory('saltybot_bringup')
+    params_file = os.path.join(pkg_share, 'config', 'rosbridge_params.yaml')
+
+    # ── rosbridge WebSocket server ────────────────────────────────────────────
+    rosbridge = Node(
+        package='rosbridge_server',
+        executable='rosbridge_websocket',
+        name='rosbridge_websocket',
+        parameters=[params_file],
+        output='screen',
+    )
+
+    # ── Compressed image republishers ─────────────────────────────────────────
+    # image_transport/republish subscribes to raw sensor_msgs/Image and
+    # re-publishes as sensor_msgs/CompressedImage using the compressed plugin.
+    #
+    # Node arguments: ['raw', 'compressed']
+    #   'raw'        — input transport type
+    #   'compressed' — output transport type
+    #
+    # Topic remappings:
+    #   in              →  /camera/<name>/image_raw
+    #   out/compressed  →  /camera/<name>/image_raw/compressed
+    #
+    # Parameter jpeg_quality controls JPEG encoder quality for the
+    # compressed publisher.  The full parameter path in ROS2 is:
+    #   /<node_name>/compressed/jpeg_quality
+    republishers = [
+        Node(
+            package='image_transport',
+            executable='republish',
+            name=f'compress_{name}',
+            arguments=['raw', 'compressed'],
+            remappings=[
+                ('in',             f'/camera/{name}/image_raw'),
+                ('out/compressed', f'/camera/{name}/image_raw/compressed'),
+            ],
+            parameters=[{
+                'compressed.jpeg_quality': _JPEG_QUALITY,
+            }],
+            output='screen',
+        )
+        for name in _CAMERAS
+    ]
+
+    return LaunchDescription([rosbridge] + republishers)

jetson/ros2_ws/src/saltybot_bringup/package.xml

@@ -15,6 +15,9 @@
   <exec_depend>nav2_bringup</exec_depend>
   <exec_depend>robot_state_publisher</exec_depend>
   <exec_depend>tf2_ros</exec_depend>
+  <exec_depend>rosbridge_server</exec_depend>
+  <exec_depend>image_transport</exec_depend>
+  <exec_depend>image_transport_plugins</exec_depend>
 
   <buildtool_depend>ament_python</buildtool_depend>