jetson/ros2_ws/src/saltybot_nav2_slam/config/map_saver_params.yaml

@@ -0,0 +1,22 @@
+# map_saver_params.yaml — nav2_map_server map_saver_server config (Issue #696)
+#
+# map_saver_server is a lifecycle node from nav2_map_server that exposes the
+# /map_saver/save_map action (nav2_msgs/action/SaveMap).  It is included in
+# the SLAM bringup so operators can trigger a map save without restarting.
+#
+# Save a map (while SLAM is running):
+#   ros2 run nav2_map_server map_saver_cli \
+#       -f /mnt/nvme/saltybot/maps/saltybot_map --map_subscribe_transient_local
+#
+# Or via action:
+#   ros2 action send_goal /map_saver/save_map nav2_msgs/action/SaveMap \
+#       '{map_topic: "map", map_url: "/mnt/nvme/saltybot/maps/saltybot_map",
+#         image_format: "pgm", map_mode: "trinary",
+#         free_thresh: 0.25, occupied_thresh: 0.65}'
+
+map_saver:
+  ros__parameters:
+    save_map_timeout:          5.0    # s — time to wait for /map topic on save
+    free_thresh_default:       0.25   # p ≤ 0.25 → free cell
+    occupied_thresh_default:   0.65   # p ≥ 0.65 → occupied cell
+    map_subscribe_transient_local: true  # use transient-local QoS (required for /map)

jetson/ros2_ws/src/saltybot_nav2_slam/launch/map_persistence.launch.py

@@ -0,0 +1,143 @@
+"""
+map_persistence.launch.py — Map save/load lifecycle nodes (Issue #696).
+
+Launches:
+  1. map_saver_server  — nav2_map_server lifecycle node; exposes
+                         /map_saver/save_map action (nav2_msgs/action/SaveMap)
+  2. saltybot_map_saver — helper node: /saltybot/save_map Trigger service,
+                          startup check, optional auto-save on shutdown
+  3. lifecycle_manager_map_saver — manages map_saver_server transitions
+
+Arguments
+─────────
+  map_dir      path to map storage directory
+               (default: /mnt/nvme/saltybot/maps)
+  map_name     base filename for saved map, no extension
+               (default: saltybot_map)
+  use_sim_time (default: false)
+  autostart    lifecycle manager autostart (default: true)
+
+Save a map (CLI shortcut while SLAM is running):
+  ros2 service call /saltybot/save_map std_srvs/srv/Trigger {}
+
+Or directly via map_saver_cli:
+  ros2 run nav2_map_server map_saver_cli \\
+      -f /mnt/nvme/saltybot/maps/saltybot_map --map_subscribe_transient_local
+
+Load on next startup:
+  ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py
+      # auto-detects /mnt/nvme/saltybot/maps/saltybot_map.yaml if present
+"""
+
+import os
+
+from ament_index_python.packages import get_package_share_directory
+
+from launch import LaunchDescription
+from launch.actions import DeclareLaunchArgument, LogInfo
+from launch.substitutions import LaunchConfiguration
+from launch_ros.actions import Node
+
+
+def generate_launch_description() -> LaunchDescription:
+    nav2_slam_dir = get_package_share_directory("saltybot_nav2_slam")
+    map_saver_params = os.path.join(nav2_slam_dir, "config", "map_saver_params.yaml")
+
+    # ── Arguments ─────────────────────────────────────────────────────────────
+
+    map_dir_arg = DeclareLaunchArgument(
+        "map_dir",
+        default_value="/mnt/nvme/saltybot/maps",
+        description="Directory for saving/loading map files (.yaml + .pgm)",
+    )
+
+    map_name_arg = DeclareLaunchArgument(
+        "map_name",
+        default_value="saltybot_map",
+        description="Base filename for saved map (no extension)",
+    )
+
+    use_sim_time_arg = DeclareLaunchArgument(
+        "use_sim_time",
+        default_value="false",
+        description="Use simulated clock",
+    )
+
+    autostart_arg = DeclareLaunchArgument(
+        "autostart",
+        default_value="true",
+        description="Automatically configure/activate lifecycle nodes",
+    )
+
+    # ── Substitutions ─────────────────────────────────────────────────────────
+
+    map_dir      = LaunchConfiguration("map_dir")
+    map_name     = LaunchConfiguration("map_name")
+    use_sim_time = LaunchConfiguration("use_sim_time")
+    autostart    = LaunchConfiguration("autostart")
+
+    # ── map_saver_server (nav2_map_server lifecycle node) ─────────────────────
+    # Exposes /map_saver/save_map action server when active.
+
+    map_saver_server = Node(
+        package="nav2_map_server",
+        executable="map_saver_server",
+        name="map_saver",
+        output="screen",
+        respawn=True,
+        respawn_delay=2.0,
+        parameters=[
+            map_saver_params,
+            {"use_sim_time": use_sim_time},
+        ],
+    )
+
+    # ── saltybot_map_saver helper node ────────────────────────────────────────
+    # /saltybot/save_map Trigger service + startup reporting + auto-save.
+
+    map_saver_helper = Node(
+        package="saltybot_nav2_slam",
+        executable="map_saver_node",
+        name="saltybot_map_saver",
+        output="screen",
+        parameters=[
+            {
+                "map_dir":              map_dir,
+                "map_name":             map_name,
+                "auto_save_on_shutdown": True,
+                "use_sim_time":         use_sim_time,
+            }
+        ],
+    )
+
+    # ── Lifecycle manager for map_saver_server ────────────────────────────────
+
+    lifecycle_manager = Node(
+        package="nav2_lifecycle_manager",
+        executable="lifecycle_manager",
+        name="lifecycle_manager_map_saver",
+        output="screen",
+        parameters=[
+            {
+                "use_sim_time": use_sim_time,
+                "autostart":    autostart,
+                "node_names":   ["map_saver"],
+            }
+        ],
+    )
+
+    return LaunchDescription([
+        # Arguments
+        map_dir_arg,
+        map_name_arg,
+        use_sim_time_arg,
+        autostart_arg,
+
+        # Banner
+        LogInfo(msg="[map_persistence] Starting map_saver_server + helper (Issue #696)"),
+
+        # Nodes
+        map_saver_server,
+        map_saver_helper,
+        lifecycle_manager,
+    ])

jetson/ros2_ws/src/saltybot_nav2_slam/launch/nav2_amcl_bringup.launch.py

@@ -1,188 +1,96 @@
-"""
-nav2_amcl_bringup.launch.py — Nav2 with AMCL localization (Issue #655).
+"""nav2_amcl_bringup.launch.py (Issue #655, #696) — AMCL + auto map detection.
 
-Full autonomous navigation stack for SaltyBot using a pre-built static map
-and AMCL particle-filter localization.
+Map selection (Issue #696): if /mnt/nvme/saltybot/maps/saltybot_map.yaml exists
+at launch time, it is used automatically. Otherwise falls back to placeholder.
 
-Odometry: /odom from vesc_can_odometry (VESC CAN IDs 61/79, Issue #646)
-LiDAR:    /scan from RPLIDAR A1M8 (via saltybot_bringup sensors.launch.py)
-Map:      static OccupancyGrid loaded by map_server (defaults to placeholder)
-
-Startup sequence
-────────────────
-  1. Sensors         — RealSense D435i + RPLIDAR A1M8 drivers + static TF
-  2. VESC odometry   — /odom (differential drive from dual CAN motors)
-  3. Localization    — map_server + AMCL (nav2_bringup localization_launch.py)
-  4. Navigation      — controller + planner + behaviors + BT navigator
-                       (nav2_bringup navigation_launch.py)
-
-Arguments
-─────────
-  map            path to map YAML (default: maps/saltybot_map.yaml placeholder)
-  use_sim_time   (default: false)
-  autostart      lifecycle manager autostart (default: true)
-  params_file    Nav2 params override (default: config/amcl_nav2_params.yaml)
-  include_sensors  launch sensors.launch.py (default: true — set false if
-                   sensors are already running)
-
-Usage
-─────
-  # Minimal — sensors included, placeholder map:
+Usage:
   ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py
-
-  # With a real saved map:
-  ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py \
-      map:=/mnt/nvme/saltybot/maps/my_map.yaml
-
-  # Without sensor bringup (sensors already running):
-  ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py \
-      include_sensors:=false
-
-Integration with saltybot_bringup
-──────────────────────────────────
-  The saltybot_bringup orchestrator (saltybot_bringup.launch.py) calls
-  nav2.launch.py at t=22 s in GROUP C.  To use AMCL instead of RTAB-Map:
-    ros2 launch saltybot_bringup nav2.launch.py nav_mode:=amcl
+  ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py map_dir:=/mnt/nvme/saltybot/maps
+  ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py map:=/path/to/room.yaml
+  ros2 launch saltybot_nav2_slam nav2_amcl_bringup.launch.py include_sensors:=false
 """
 
 import os
-
 from ament_index_python.packages import get_package_share_directory
-
 from launch import LaunchDescription
-from launch.actions import (
-    DeclareLaunchArgument,
-    GroupAction,
-    IncludeLaunchDescription,
-    LogInfo,
-)
+from launch.actions import DeclareLaunchArgument, GroupAction, IncludeLaunchDescription, LogInfo
 from launch.conditions import IfCondition
 from launch.launch_description_sources import PythonLaunchDescriptionSource
 from launch.substitutions import LaunchConfiguration
 
+# Map auto-detection (Issue #696): evaluated at ros2 launch time on the Jetson.
+_NVME_MAP_DIR = "/mnt/nvme/saltybot/maps"
+_NVME_MAP_YAML = os.path.join(_NVME_MAP_DIR, "saltybot_map.yaml")
+
+
+def _default_map() -> str:
+    if os.path.isfile(_NVME_MAP_YAML):
+        return _NVME_MAP_YAML
+    nav2_slam_dir = get_package_share_directory("saltybot_nav2_slam")
+    return os.path.join(nav2_slam_dir, "maps", "saltybot_map.yaml")
+
 
 def generate_launch_description() -> LaunchDescription:
     nav2_slam_dir    = get_package_share_directory("saltybot_nav2_slam")
     bringup_dir      = get_package_share_directory("saltybot_bringup")
     nav2_bringup_dir = get_package_share_directory("nav2_bringup")
+    default_map      = _default_map()
+    default_params   = os.path.join(nav2_slam_dir, "config", "amcl_nav2_params.yaml")
+    map_source = "saved NVMe map" if default_map == _NVME_MAP_YAML else "placeholder map"
 
-    default_map    = os.path.join(nav2_slam_dir, "maps", "saltybot_map.yaml")
-    default_params = os.path.join(nav2_slam_dir, "config", "amcl_nav2_params.yaml")
-
-    # ── Launch arguments ──────────────────────────────────────────────────────
-
-    map_arg = DeclareLaunchArgument(
-        "map",
-        default_value=default_map,
-        description="Path to map YAML file (Nav2 map_server format)",
-    )
-
-    use_sim_time_arg = DeclareLaunchArgument(
-        "use_sim_time",
-        default_value="false",
-        description="Use simulated clock from /clock topic",
-    )
-
-    autostart_arg = DeclareLaunchArgument(
-        "autostart",
-        default_value="true",
-        description="Automatically start lifecycle nodes after launch",
-    )
-
-    params_file_arg = DeclareLaunchArgument(
-        "params_file",
-        default_value=default_params,
-        description="Path to Nav2 parameter YAML file",
-    )
-
-    include_sensors_arg = DeclareLaunchArgument(
-        "include_sensors",
-        default_value="true",
-        description="Launch sensors.launch.py (set false if sensors already running)",
-    )
-
-    # ── Substitutions ─────────────────────────────────────────────────────────
-
-    map_file       = LaunchConfiguration("map")
-    use_sim_time   = LaunchConfiguration("use_sim_time")
-    autostart      = LaunchConfiguration("autostart")
-    params_file    = LaunchConfiguration("params_file")
+    map_file        = LaunchConfiguration("map")
+    use_sim_time    = LaunchConfiguration("use_sim_time")
+    autostart       = LaunchConfiguration("autostart")
+    params_file     = LaunchConfiguration("params_file")
     include_sensors = LaunchConfiguration("include_sensors")
 
-    # ── Sensor bringup (conditional) ─────────────────────────────────────────
-    # RealSense D435i + RPLIDAR A1M8 drivers + base_link→laser/camera_link TF
-
-    sensors_launch = GroupAction(
-        condition=IfCondition(include_sensors),
-        actions=[
-            LogInfo(msg="[nav2_amcl] Starting sensors (RealSense + RPLIDAR)"),
-            IncludeLaunchDescription(
-                PythonLaunchDescriptionSource(
-                    os.path.join(bringup_dir, "launch", "sensors.launch.py")
-                ),
-            ),
-        ],
-    )
-
-    # ── VESC CAN odometry ────────────────────────────────────────────────────
-    # Differential drive from CAN IDs 61 (left) + 79 (right) → /odom + TF
-
-    odom_launch = IncludeLaunchDescription(
-        PythonLaunchDescriptionSource(
-            os.path.join(nav2_slam_dir, "launch", "odometry_bridge.launch.py")
-        ),
-        launch_arguments={"use_sim_time": use_sim_time}.items(),
-    )
-
-    # ── Localization: map_server + AMCL ──────────────────────────────────────
-    # Publishes: /map, TF map→odom (AMCL), /amcl_pose, /particlecloud
-
-    localization_launch = IncludeLaunchDescription(
-        PythonLaunchDescriptionSource(
-            os.path.join(nav2_bringup_dir, "launch", "localization_launch.py")
-        ),
-        launch_arguments={
-            "map":           map_file,
-            "use_sim_time":  use_sim_time,
-            "autostart":     autostart,
-            "params_file":   params_file,
-            "use_lifecycle_mgr": "true",
-        }.items(),
-    )
-
-    # ── Navigation: controller + planner + behaviors + BT navigator ──────────
-    # Subscribes: /odom, /scan, /map, /cmd_vel_nav (→ velocity_smoother → /cmd_vel)
-    # Provides: action servers for NavigateToPose + NavigateThroughPoses
-
-    navigation_launch = IncludeLaunchDescription(
-        PythonLaunchDescriptionSource(
-            os.path.join(nav2_bringup_dir, "launch", "navigation_launch.py")
-        ),
-        launch_arguments={
-            "use_sim_time":                use_sim_time,
-            "autostart":                   autostart,
-            "params_file":                 params_file,
-            "map_subscribe_transient_local": "true",
-            "use_lifecycle_mgr":           "true",
-        }.items(),
-    )
-
     return LaunchDescription([
-        # Arguments
-        map_arg,
-        use_sim_time_arg,
-        autostart_arg,
-        params_file_arg,
-        include_sensors_arg,
+        DeclareLaunchArgument("map_dir", default_value=_NVME_MAP_DIR,
+                              description="Directory containing saved map files (Issue #696)"),
+        DeclareLaunchArgument("map", default_value=default_map,
+                              description="Path to map YAML. Auto-detected: " + default_map),
+        DeclareLaunchArgument("use_sim_time", default_value="false"),
+        DeclareLaunchArgument("autostart", default_value="true"),
+        DeclareLaunchArgument("params_file", default_value=default_params),
+        DeclareLaunchArgument("include_sensors", default_value="true",
+                              description="Launch sensors.launch.py"),
 
-        # Banner
-        LogInfo(msg="[nav2_amcl] Nav2 AMCL bringup starting (Issue #655)"),
+        LogInfo(msg="[nav2_amcl] Nav2 AMCL bringup starting (Issues #655, #696)"),
+        LogInfo(msg="[nav2_amcl] Map: " + map_source + " -> " + default_map),
+
+        GroupAction(
+            condition=IfCondition(include_sensors),
+            actions=[
+                LogInfo(msg="[nav2_amcl] Starting sensors (RealSense + RPLIDAR)"),
+                IncludeLaunchDescription(
+                    PythonLaunchDescriptionSource(os.path.join(bringup_dir, "launch", "sensors.launch.py")),
+                ),
+            ],
+        ),
+
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(nav2_slam_dir, "launch", "odometry_bridge.launch.py")),
+            launch_arguments={"use_sim_time": use_sim_time}.items(),
+        ),
 
-        # Startup sequence
-        sensors_launch,                             # step 1 — sensors
-        odom_launch,                                # step 2 — /odom from VESC
         LogInfo(msg="[nav2_amcl] Starting AMCL localization"),
-        localization_launch,                        # step 3 — map_server + AMCL
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(nav2_bringup_dir, "launch", "localization_launch.py")),
+            launch_arguments={
+                "map": map_file, "use_sim_time": use_sim_time,
+                "autostart": autostart, "params_file": params_file,
+                "use_lifecycle_mgr": "true",
+            }.items(),
+        ),
+
         LogInfo(msg="[nav2_amcl] Starting Nav2 navigation stack"),
-        navigation_launch,                          # step 4 — full nav stack
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(nav2_bringup_dir, "launch", "navigation_launch.py")),
+            launch_arguments={
+                "use_sim_time": use_sim_time, "autostart": autostart,
+                "params_file": params_file,
+                "map_subscribe_transient_local": "true",
+                "use_lifecycle_mgr": "true",
+            }.items(),
+        ),
     ])

jetson/ros2_ws/src/saltybot_nav2_slam/launch/nav2_slam_bringup.launch.py

@@ -1,66 +1,65 @@
-"""Nav2 SLAM Bringup for SaltyBot (Issue #422)"""
+"""nav2_slam_bringup.launch.py (Issue #422, #696) — SLAM + map persistence."""
 
 import os
+from ament_index_python.packages import get_package_share_directory
 from launch import LaunchDescription
-from launch.actions import IncludeLaunchDescription, DeclareLaunchArgument
+from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription
 from launch.launch_description_sources import PythonLaunchDescriptionSource
 from launch.substitutions import LaunchConfiguration
-from ament_index_python.packages import get_package_share_directory
 
 
 def generate_launch_description():
-    nav2_slam_dir = get_package_share_directory('saltybot_nav2_slam')
-    bringup_dir = get_package_share_directory('saltybot_bringup')
+    nav2_slam_dir = get_package_share_directory("saltybot_nav2_slam")
+    bringup_dir = get_package_share_directory("saltybot_bringup")
+    nav2_params = os.path.join(nav2_slam_dir, "config", "nav2_params.yaml")
+    slam_params = os.path.join(nav2_slam_dir, "config", "slam_toolbox_params.yaml")
 
-    nav2_params = os.path.join(nav2_slam_dir, 'config', 'nav2_params.yaml')
-    slam_params = os.path.join(nav2_slam_dir, 'config', 'slam_toolbox_params.yaml')
+    use_sim_time = LaunchConfiguration("use_sim_time")
+    map_dir = LaunchConfiguration("map_dir")
+    map_name = LaunchConfiguration("map_name")
 
     return LaunchDescription([
-        DeclareLaunchArgument('use_sim_time', default_value='false'),
-
-        IncludeLaunchDescription(
-            PythonLaunchDescriptionSource(
-                os.path.join(bringup_dir, 'launch', 'sensors.launch.py')
-            ),
-            launch_arguments={'use_sim_time': LaunchConfiguration('use_sim_time')}.items(),
+        DeclareLaunchArgument("use_sim_time", default_value="false"),
+        DeclareLaunchArgument(
+            "map_dir",
+            default_value="/mnt/nvme/saltybot/maps",
+            description="Directory for saving/loading map files (Issue #696)",
         ),
-
-        IncludeLaunchDescription(
-            PythonLaunchDescriptionSource(
-                os.path.join(nav2_slam_dir, 'launch', 'odometry_bridge.launch.py')
-            ),
-            launch_arguments={'use_sim_time': LaunchConfiguration('use_sim_time')}.items(),
+        DeclareLaunchArgument(
+            "map_name",
+            default_value="saltybot_map",
+            description="Base filename for saved map (no extension)",
+        ),
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(bringup_dir, "launch", "sensors.launch.py")),
+            launch_arguments={"use_sim_time": use_sim_time}.items(),
+        ),
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(nav2_slam_dir, "launch", "odometry_bridge.launch.py")),
+            launch_arguments={"use_sim_time": use_sim_time}.items(),
+        ),
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(nav2_slam_dir, "launch", "nav2_slam_integrated.launch.py")),
+            launch_arguments={"slam_params_file": slam_params, "use_sim_time": use_sim_time}.items(),
+        ),
+        IncludeLaunchDescription(
+            PythonLaunchDescriptionSource(os.path.join(nav2_slam_dir, "launch", "depth_to_costmap.launch.py")),
+            launch_arguments={"use_sim_time": use_sim_time}.items(),
         ),
-
         IncludeLaunchDescription(
             PythonLaunchDescriptionSource(
-                os.path.join(nav2_slam_dir, 'launch', 'nav2_slam_integrated.launch.py')
+                os.path.join(get_package_share_directory("nav2_bringup"), "launch", "navigation_launch.py")
             ),
             launch_arguments={
-                'slam_params_file': slam_params,
-                'use_sim_time': LaunchConfiguration('use_sim_time'),
+                "use_sim_time": use_sim_time,
+                "params_file": nav2_params,
+                "autostart": "true",
+                "map_subscribe_transient_local": "true",
             }.items(),
         ),
-
+        # Map persistence (Issue #696): map_saver_server + /saltybot/save_map service
         IncludeLaunchDescription(
-            PythonLaunchDescriptionSource(
-                os.path.join(nav2_slam_dir, 'launch', 'depth_to_costmap.launch.py')
-            ),
-            launch_arguments={'use_sim_time': LaunchConfiguration('use_sim_time')}.items(),
-        ),
-
-        IncludeLaunchDescription(
-            PythonLaunchDescriptionSource(
-                os.path.join(
-                    get_package_share_directory('nav2_bringup'),
-                    'launch', 'navigation_launch.py'
-                )
-            ),
-            launch_arguments={
-                'use_sim_time': LaunchConfiguration('use_sim_time'),
-                'params_file': nav2_params,
-                'autostart': 'true',
-                'map_subscribe_transient_local': 'true',
-            }.items(),
+            PythonLaunchDescriptionSource(os.path.join(nav2_slam_dir, "launch", "map_persistence.launch.py")),
+            launch_arguments={"map_dir": map_dir, "map_name": map_name, "use_sim_time": use_sim_time}.items(),
         ),
     ])

jetson/ros2_ws/src/saltybot_nav2_slam/saltybot_nav2_slam/map_saver_node.py

@@ -0,0 +1,145 @@
+#!/usr/bin/env python3
+"""
+map_saver_node.py — Map persistence helper for SLAM → AMCL hand-off (Issue #696).
+
+Responsibilities:
+  1. On startup: report whether a saved map exists at map_dir/map_name.yaml
+     (the path that nav2_amcl_bringup.launch.py will load on next boot).
+  2. Provide /saltybot/save_map (std_srvs/Trigger) — triggers map_saver_cli
+     to save the current /map topic to map_dir/map_name.{yaml,pgm}.
+  3. On shutdown: if auto_save_on_shutdown is true, save the final map.
+
+Parameters:
+  map_dir              (str)  default /mnt/nvme/saltybot/maps
+  map_name             (str)  default saltybot_map
+  auto_save_on_shutdown (bool) default true
+
+The saved map is loaded automatically by nav2_amcl_bringup.launch.py on the
+next startup when the file is present at map_dir/map_name.yaml.
+"""
+
+import os
+import subprocess
+
+import rclpy
+from rclpy.node import Node
+from std_srvs.srv import Trigger
+
+
+class MapSaverNode(Node):
+    """Helper node for SLAM map persistence and AMCL pre-load."""
+
+    def __init__(self) -> None:
+        super().__init__("saltybot_map_saver")
+
+        self.declare_parameter("map_dir",              "/mnt/nvme/saltybot/maps")
+        self.declare_parameter("map_name",             "saltybot_map")
+        self.declare_parameter("auto_save_on_shutdown", True)
+
+        self._map_dir   = self.get_parameter("map_dir").value
+        self._map_name  = self.get_parameter("map_name").value
+        self._auto_save = self.get_parameter("auto_save_on_shutdown").value
+
+        self._map_prefix = os.path.join(self._map_dir, self._map_name)
+        self._map_yaml   = self._map_prefix + ".yaml"
+
+        # ── Ensure map directory exists ────────────────────────────────────────
+        os.makedirs(self._map_dir, exist_ok=True)
+
+        # ── Report saved map status ────────────────────────────────────────────
+        if os.path.isfile(self._map_yaml):
+            self.get_logger().info(
+                f"[map_saver] Saved map found: {self._map_yaml} — "
+                "AMCL will load this map on next startup."
+            )
+        else:
+            self.get_logger().warn(
+                f"[map_saver] No saved map at {self._map_yaml} — "
+                "AMCL will use the placeholder map. "
+                "Run SLAM, then call /saltybot/save_map to persist."
+            )
+
+        # ── Service: /saltybot/save_map ────────────────────────────────────────
+        self._save_srv = self.create_service(
+            Trigger,
+            "/saltybot/save_map",
+            self._on_save_map,
+        )
+
+        self.get_logger().info(
+            f"[map_saver] Ready. map_dir={self._map_dir} map_name={self._map_name} "
+            f"auto_save_on_shutdown={self._auto_save}"
+        )
+
+    # ── Service callback ───────────────────────────────────────────────────────
+
+    def _on_save_map(
+        self, _request: Trigger.Request, response: Trigger.Response
+    ) -> Trigger.Response:
+        """Save current /map to map_dir/map_name.{yaml,pgm} via map_saver_cli."""
+        success, message = self._save_map()
+        response.success = success
+        response.message = message
+        return response
+
+    # ── Map save helper ────────────────────────────────────────────────────────
+
+    def _save_map(self) -> tuple[bool, str]:
+        """
+        Call nav2_map_server map_saver_cli to write the current /map.
+
+        Returns (success, message).
+        """
+        cmd = [
+            "ros2", "run", "nav2_map_server", "map_saver_cli",
+            "-f", self._map_prefix,
+            "--map_subscribe_transient_local",
+        ]
+        self.get_logger().info(f"[map_saver] Saving map to {self._map_prefix}.*")
+        try:
+            result = subprocess.run(
+                cmd,
+                timeout=10,
+                capture_output=True,
+                text=True,
+            )
+            if result.returncode == 0:
+                msg = f"Map saved to {self._map_yaml}"
+                self.get_logger().info(f"[map_saver] {msg}")
+                return True, msg
+            else:
+                msg = f"map_saver_cli failed (rc={result.returncode}): {result.stderr.strip()}"
+                self.get_logger().error(f"[map_saver] {msg}")
+                return False, msg
+        except subprocess.TimeoutExpired:
+            msg = "map_saver_cli timed out after 10 s (is /map published?)"
+            self.get_logger().error(f"[map_saver] {msg}")
+            return False, msg
+        except Exception as exc:  # noqa: BLE001
+            msg = f"map_saver_cli exception: {exc}"
+            self.get_logger().error(f"[map_saver] {msg}")
+            return False, msg
+
+    # ── Lifecycle ──────────────────────────────────────────────────────────────
+
+    def destroy_node(self) -> None:
+        if self._auto_save:
+            self.get_logger().info("[map_saver] Shutdown — auto-saving map...")
+            self._save_map()
+        super().destroy_node()
+
+
+def main(args=None) -> None:
+    rclpy.init(args=args)
+    node = MapSaverNode()
+    try:
+        rclpy.spin(node)
+    except KeyboardInterrupt:
+        pass
+    finally:
+        node.destroy_node()
+        rclpy.shutdown()
+
+
+if __name__ == "__main__":
+    main()

jetson/ros2_ws/src/saltybot_nav2_slam/setup.py

@@ -15,6 +15,7 @@ setup(
             "launch/depth_to_costmap.launch.py",
             "launch/odometry_bridge.launch.py",
             "launch/nav2_amcl_bringup.launch.py",
+            "launch/map_persistence.launch.py",
         ]),
         (f"share/{package_name}/config", [
             "config/nav2_params.yaml",
@@ -25,6 +26,7 @@ setup(
             "config/dwb_local_planner_params.yaml",
             "config/vesc_odometry_params.yaml",
             "config/amcl_nav2_params.yaml",
+            "config/map_saver_params.yaml",
         ]),
         (f"share/{package_name}/maps", [
             "maps/saltybot_map.yaml",
@@ -42,6 +44,7 @@ setup(
         "console_scripts": [
             "vesc_odometry_bridge = saltybot_nav2_slam.vesc_odometry_bridge:main",
             "vesc_can_odometry = saltybot_nav2_slam.vesc_odometry_bridge:main",
+            "map_saver_node = saltybot_nav2_slam.map_saver_node:main",
         ],
     },
 )

jetson/ros2_ws/src/saltybot_nav2_slam/test/test_nav2_amcl.py

@@ -334,5 +334,125 @@ def test_launch_file_has_map_argument():
     assert '"map"' in src or "'map'" in src
 
 
+
+# ── map_saver_params.yaml + map_persistence files (Issue #696) ───────────────
+
+import os as _os
+_PKG_ROOT2 = _os.path.join(_os.path.dirname(__file__), "..")
+_MAP_SAVER_CFG  = _os.path.join(_PKG_ROOT2, "config", "map_saver_params.yaml")
+_SLAM_LAUNCH    = _os.path.join(_PKG_ROOT2, "launch", "nav2_slam_bringup.launch.py")
+_PERSIST_LAUNCH = _os.path.join(_PKG_ROOT2, "launch", "map_persistence.launch.py")
+_SAVER_NODE     = _os.path.join(_PKG_ROOT2, "saltybot_nav2_slam", "map_saver_node.py")
+
+
+def _load_map_saver_params():
+    import yaml
+    with open(_MAP_SAVER_CFG) as f:
+        return yaml.safe_load(f)
+
+
+def test_map_saver_params_file_exists():
+    assert _os.path.isfile(_MAP_SAVER_CFG)
+
+
+def test_map_saver_params_required_keys():
+    p = _load_map_saver_params()["map_saver"]["ros__parameters"]
+    for key in ("save_map_timeout", "free_thresh_default",
+                "occupied_thresh_default", "map_subscribe_transient_local"):
+        assert key in p, f"map_saver_params missing: {key}"
+
+
+def test_map_saver_thresholds_valid():
+    p = _load_map_saver_params()["map_saver"]["ros__parameters"]
+    assert 0.0 < p["free_thresh_default"] < p["occupied_thresh_default"] < 1.0
+
+
+def test_map_saver_timeout_positive():
+    p = _load_map_saver_params()["map_saver"]["ros__parameters"]
+    assert p["save_map_timeout"] > 0.0
+
+
+def test_map_persistence_launch_exists():
+    assert _os.path.isfile(_PERSIST_LAUNCH)
+
+
+def test_map_persistence_launch_syntax():
+    import py_compile
+    py_compile.compile(_PERSIST_LAUNCH, doraise=True)
+
+
+def test_map_persistence_launch_has_map_saver_server():
+    with open(_PERSIST_LAUNCH) as f:
+        src = f.read()
+    assert "map_saver_server" in src
+
+
+def test_map_persistence_launch_has_lifecycle_manager():
+    with open(_PERSIST_LAUNCH) as f:
+        src = f.read()
+    assert "lifecycle_manager" in src
+
+
+def test_map_persistence_launch_has_map_dir_arg():
+    with open(_PERSIST_LAUNCH) as f:
+        src = f.read()
+    assert "map_dir" in src
+
+
+def test_map_saver_node_exists():
+    assert _os.path.isfile(_SAVER_NODE)
+
+
+def test_map_saver_node_syntax():
+    import py_compile
+    py_compile.compile(_SAVER_NODE, doraise=True)
+
+
+def test_map_saver_node_has_save_service():
+    with open(_SAVER_NODE) as f:
+        src = f.read()
+    assert "/saltybot/save_map" in src
+
+
+def test_map_saver_node_calls_map_saver_cli():
+    with open(_SAVER_NODE) as f:
+        src = f.read()
+    assert "map_saver_cli" in src
+
+
+def test_map_saver_node_has_auto_save_shutdown():
+    with open(_SAVER_NODE) as f:
+        src = f.read()
+    assert "auto_save_on_shutdown" in src
+
+
+def test_slam_bringup_includes_map_persistence():
+    with open(_SLAM_LAUNCH) as f:
+        src = f.read()
+    assert "map_persistence.launch.py" in src
+
+
+def test_slam_bringup_has_map_dir_arg():
+    with open(_SLAM_LAUNCH) as f:
+        src = f.read()
+    assert "map_dir" in src
+
+
+def test_amcl_launch_has_map_dir_arg():
+    import os as __os
+    _LAUNCH2 = __os.path.join(__os.path.dirname(__file__), "..", "launch", "nav2_amcl_bringup.launch.py")
+    with open(_LAUNCH2) as f:
+        src = f.read()
+    assert "map_dir" in src
+
+
+def test_amcl_launch_has_auto_detect_logic():
+    import os as __os
+    _LAUNCH2 = __os.path.join(__os.path.dirname(__file__), "..", "launch", "nav2_amcl_bringup.launch.py")
+    with open(_LAUNCH2) as f:
+        src = f.read()
+    assert "/mnt/nvme/saltybot/maps" in src
+    assert "isfile" in src or "os.path" in src
+
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])