diff --git a/src/iiwa_experement/iiwa_experement/runtime_config.py b/src/iiwa_experement/iiwa_experement/runtime_config.py
index 58beec9..41d9307 100644
--- a/src/iiwa_experement/iiwa_experement/runtime_config.py
+++ b/src/iiwa_experement/iiwa_experement/runtime_config.py
@@ -17,7 +17,7 @@ import yaml
 
 
 EXPERIMENT_IDS = tuple(range(1, 21))
-MODES = ('view', 'execute')
+MODES = ('view', 'execute', 'planner')
 DEFAULT_START_DELAY_SEC = 3.0
 DEFAULT_TRACE_DIR = '~/.ros/iiwa_experement/runs'
 LOCAL_PROTOS = (
diff --git a/src/iiwa_experement/launch/experiment.launch.py b/src/iiwa_experement/launch/experiment.launch.py
index 4c2f24a..f24a197 100644
--- a/src/iiwa_experement/launch/experiment.launch.py
+++ b/src/iiwa_experement/launch/experiment.launch.py
@@ -110,6 +110,11 @@ def supervisor_process(
     )
 
 
+def mode_read_only(mode: str) -> bool:
+    """Only ``view`` is passive; execute and planner accept grab commands."""
+    return mode == 'view'
+
+
 def runtime_actions(
     experiment_id: int,
     scene_config: str,
@@ -126,7 +131,10 @@ def runtime_actions(
     package_share = Path(get_package_share_directory('iiwa_experement'))
     if geometry_path is None:
         geometry_path = str(package_share / 'config' / 'geometry.yaml')
-    read_only = mode != 'execute'
+    # Only the passive view mode locks the supervisor.  Both the reference
+    # executor and the external-graph planner need to accept grab/dock
+    # commands; the planner mode simply never starts the reference runner.
+    read_only = mode_read_only(mode)
     actions = [
         IncludeLaunchDescription(
             PythonLaunchDescriptionSource(
@@ -264,7 +272,9 @@ def generate_launch_description():
             default_value='view',
             description=(
                 'view = open the prepared scene without motion; '
-                'execute = run the reference sequence after start_delay_sec.'
+                'execute = run the reference sequence after start_delay_sec; '
+                'planner = writable scene for an externally supplied graph, '
+                'no reference sequence.'
             ),
         ),
         DeclareLaunchArgument(
diff --git a/src/iiwa_experement/test/test_launch.py b/src/iiwa_experement/test/test_launch.py
index 6449958..e428a7c 100644
--- a/src/iiwa_experement/test/test_launch.py
+++ b/src/iiwa_experement/test/test_launch.py
@@ -45,12 +45,17 @@ def test_invalid_experiment_ids_are_rejected(raw):
         validate_experiment_id(raw)
 
 
-@pytest.mark.parametrize('raw, expected', [('view', 'view'), ('execute', 'execute'), (' VIEW ', 'view')])
+@pytest.mark.parametrize('raw, expected', [
+    ('view', 'view'),
+    ('execute', 'execute'),
+    ('planner', 'planner'),
+    (' VIEW ', 'view'),
+])
 def test_valid_modes(raw, expected):
     assert validate_mode(raw) == expected
 
 
-@pytest.mark.parametrize('raw', ['', 'run', 'VIEW '[:-1] + 'x', '1'])
+@pytest.mark.parametrize('raw', ['', 'run', 'VIEW '[:-1] + 'x', '1', 'plan'])
 def test_invalid_modes_are_rejected(raw):
     with pytest.raises(ValueError):
         validate_mode(raw)
@@ -138,6 +143,46 @@ def test_execute_adds_the_reference_runner_after_the_supervisor():
     assert any(type(action) is ExecuteProcess for action in actions)
 
 
+def _process_arguments(process):
+    return [item[0].text for item in process.cmd if item and item[0].text]
+
+
+def test_planner_is_writable_and_has_no_reference_runner():
+    module = load_launch_module()
+    actions = module.runtime_actions(
+        experiment_id=20,
+        scene_config='/tmp/scenes.yaml',
+        setting_path='/tmp/setting.yaml',
+        mode='planner',
+    )
+    assert not any(
+        isinstance(action, Node) and action.node_executable == 'reference_runner'
+        for action in actions
+    )
+    processes = [action for action in actions if type(action) is ExecuteProcess]
+    assert len(processes) == 1
+    assert 'read_only:=false' in _process_arguments(processes[0])
+    assert module.mode_read_only('planner') is False
+    parameters = module.supervisor_parameters(
+        20, '/tmp/scenes.yaml', '/tmp/geometry.yaml', False,
+    )
+    assert parameters['read_only'] is False
+
+
+def test_view_remains_read_only_after_adding_the_planner_mode():
+    module = load_launch_module()
+    actions = module.runtime_actions(
+        experiment_id=1,
+        scene_config='/tmp/scenes.yaml',
+        setting_path='/tmp/setting.yaml',
+        mode='view',
+    )
+    processes = [action for action in actions if type(action) is ExecuteProcess]
+    assert 'read_only:=true' in _process_arguments(processes[0])
+    assert module.mode_read_only('view') is True
+    assert module.mode_read_only('execute') is False
+
+
 def test_runtime_actions_can_register_cleanup(tmp_path):
     module = load_launch_module()
     actions = module.runtime_actions(
diff --git a/src/iiwa_experement/test/test_runtime_config.py b/src/iiwa_experement/test/test_runtime_config.py
index f135a3a..4c5e038 100644
--- a/src/iiwa_experement/test/test_runtime_config.py
+++ b/src/iiwa_experement/test/test_runtime_config.py
@@ -14,12 +14,17 @@ from iiwa_experement.runtime_config import (
 )
 
 
-@pytest.mark.parametrize('raw, expected', [('view', 'view'), (' Execute ', 'execute')])
+@pytest.mark.parametrize('raw, expected', [
+    ('view', 'view'),
+    (' Execute ', 'execute'),
+    ('planner', 'planner'),
+    (' PLANNER ', 'planner'),
+])
 def test_mode_validation(raw, expected):
     assert validate_mode(raw) == expected
 
 
-@pytest.mark.parametrize('raw', ['', 'motion', 'execute!'])
+@pytest.mark.parametrize('raw', ['', 'motion', 'execute!', 'plan'])
 def test_mode_validation_rejects_unknown_modes(raw):
     with pytest.raises(ValueError):
         validate_mode(raw)