diff --git a/python/mujoco/experimental/studio/launch_passive.py b/python/mujoco/experimental/studio/launch_passive.py
index 708e75f1..1c6d05c4 100644
--- a/python/mujoco/experimental/studio/launch_passive.py
+++ b/python/mujoco/experimental/studio/launch_passive.py
@@ -86,26 +86,21 @@ def run_viewer_target(
   """Creates the appropriate viewer and runs the viewer loop.
 
   Args:
-    config: Configuration specifying the viewer mode and window settings.
+    config: Configuration specifying the viewer window settings.
     viewer_endpoint: Endpoint for communicating with the simulation side.
     handlers: Optional list of viewer-side handler instances, which are classes
       with methods decorated with ``@handler``.
-
-  Raises:
-    ValueError: If the viewer mode requested in config is unknown.
   """
-  if config.viewer_mode == viewer_protocol.ViewerMode.NATIVE:
+  if config.gfx in ('web', 'webgl'):  # In future we may add 'webgpu' here too.
+    from mujoco.experimental.studio import web_viewer  # pylint: disable=g-import-not-at-top
+
+    viewer = web_viewer.WebViewer(config, viewer_endpoint, handlers=handlers)
+  else:
     from mujoco.experimental.studio import native_viewer  # pylint: disable=g-import-not-at-top
 
     viewer = native_viewer.NativeViewer(
         config, viewer_endpoint, handlers=handlers
     )
-  elif config.viewer_mode == viewer_protocol.ViewerMode.WEB:
-    from mujoco.experimental.studio import web_viewer  # pylint: disable=g-import-not-at-top
-
-    viewer = web_viewer.WebViewer(config, viewer_endpoint, handlers=handlers)
-  else:
-    raise ValueError(f'Unknown viewer mode: {config.viewer_mode!r}')
 
   viewer_protocol.run_viewer_loop(viewer)
 
diff --git a/python/mujoco/experimental/studio/sample/ghost.py b/python/mujoco/experimental/studio/sample/ghost.py
index cd95989e..213b6450 100644
--- a/python/mujoco/experimental/studio/sample/ghost.py
+++ b/python/mujoco/experimental/studio/sample/ghost.py
@@ -38,12 +38,15 @@ from mujoco.experimental.dear_imgui import dear_imgui as imgui
 
 vp = viewer_protocol
 
-_GFX = _flags.DEFINE_enum('gfx', None, vp.GFX_MODES, 'Graphics mode.')
+_MODEL = _flags.DEFINE_string('model', None, 'Path to model file.')
+_GFX = _flags.DEFINE_enum(
+    'gfx', None, vp.GFX_MODES, 'Graphics mode ("web" launches Web Viewer).'
+)
+_PORT = _flags.DEFINE_integer(
+    'port', 0, 'Web Viewer port (0 picks first free port >= 8080).'
+)
 _WIDTH = _flags.DEFINE_integer('width', 1200, 'Width of the output image.')
 _HEIGHT = _flags.DEFINE_integer('height', 800, 'Height of the output image')
-_VIEWER = _flags.DEFINE_enum_class(
-    'viewer', vp.ViewerMode.NATIVE, vp.ViewerMode, 'Viewer mode.'
-)
 
 
 class GhostRenderer:
@@ -155,15 +158,18 @@ class GhostRenderer:
 
 
 def main(argv: list[str]) -> None:
-  if len(argv) != 2:
-    raise _app.UsageError('Please provide exactly one MJCF path argument.')
+  model_path = _MODEL.value or (
+      argv[1] if len(argv) > 1 and not argv[1].startswith('--') else None
+  )
+  if not model_path:
+    raise _app.UsageError('Please provide a model path argument or --model flag.')
 
   data = None
   try:
-    if (data := parser.parse(argv[1])) is None:
+    if (data := parser.parse(model_path)) is None:
       raise ValueError('parser returned None')
   except Exception as ex:  # pylint: disable=broad-except
-    print(f'Failed to load model from {argv[1]!r}: {ex}')
+    print(f'Failed to load model from {model_path!r}: {ex}')
     sys.exit(1)
   model = data.model
 
@@ -172,7 +178,7 @@ def main(argv: list[str]) -> None:
       width=_WIDTH.value,
       height=_HEIGHT.value,
       gfx=_GFX.value or '',
-      viewer_mode=_VIEWER.value,
+      http_port=_PORT.value,
   )
 
   ghost_renderer = GhostRenderer()
diff --git a/python/mujoco/experimental/studio/sample/implot.py b/python/mujoco/experimental/studio/sample/implot.py
index a50324cc..7ff57b43 100644
--- a/python/mujoco/experimental/studio/sample/implot.py
+++ b/python/mujoco/experimental/studio/sample/implot.py
@@ -17,7 +17,7 @@ This script runs a Studio viewer and adds an 'Inspect Body' window using ImGui
 and ImPlot bindings to visualize selected body data. The example demonstrates
 how responsive UI layout rules are easily implemented.
 
-Provide an MJCF model file via the first command-line argument to launch.
+Provide a model file via the --model flag or positional argument to launch.
 """
 
 import math
@@ -40,12 +40,15 @@ from mujoco.experimental.implot import implot
 
 vp = viewer_protocol
 
-_GFX = _flags.DEFINE_enum('gfx', None, vp.GFX_MODES, 'Graphics mode.')
+_MODEL = _flags.DEFINE_string('model', None, 'Path to model file.')
+_GFX = _flags.DEFINE_enum(
+    'gfx', None, vp.GFX_MODES, 'Graphics mode ("web" launches Web Viewer).'
+)
+_PORT = _flags.DEFINE_integer(
+    'port', 0, 'Web Viewer port (0 picks first free port >= 8080).'
+)
 _WIDTH = _flags.DEFINE_integer('width', 1200, 'Width of the output image.')
 _HEIGHT = _flags.DEFINE_integer('height', 800, 'Height of the output image')
-_VIEWER = _flags.DEFINE_enum_class(
-    'viewer', vp.ViewerMode.NATIVE, vp.ViewerMode, 'Viewer mode.'
-)
 
 
 _N_HISTORY = 100
@@ -211,12 +214,15 @@ class BodyInspector:
 
 
 def main(argv: list[str]) -> None:
-  if len(argv) < 2:
-    print('Usage: implot <model_path.xml>')
+  model_path = _MODEL.value or (
+      argv[1] if len(argv) > 1 and not argv[1].startswith('--') else None
+  )
+  if not model_path:
+    print('Usage: implot --model=<model_path.xml>')
     sys.exit(1)
 
-  if (data := parser.parse(argv[1])) is None:
-    print(f'Error loading model from {argv[1]!r}')
+  if (data := parser.parse(model_path)) is None:
+    print(f'Error loading model from {model_path!r}')
     sys.exit(1)
   model = data.model
 
@@ -227,7 +233,7 @@ def main(argv: list[str]) -> None:
       width=_WIDTH.value,
       height=_HEIGHT.value,
       gfx=_GFX.value or '',
-      viewer_mode=_VIEWER.value,
+      http_port=_PORT.value,
   )
 
   with launch_passive.launch_passive(
diff --git a/python/mujoco/experimental/studio/sample/render.py b/python/mujoco/experimental/studio/sample/render.py
index a3431de2..07594b6c 100644
--- a/python/mujoco/experimental/studio/sample/render.py
+++ b/python/mujoco/experimental/studio/sample/render.py
@@ -16,37 +16,38 @@
 import os
 import sys
 
-from absl import app
-from absl import flags
+from absl import app as _app
+from absl import flags as _flags
 import mujoco
 from mujoco.experimental.studio import parser
 from mujoco.experimental.studio import renderer
 from mujoco.experimental.studio import viewer_protocol
 from PIL import Image
 
-_MODEL = flags.DEFINE_string('model', '', 'Model file to load.')
-_OUTPUT = flags.DEFINE_string('output', '', 'Output file to save.')
-_GFX = flags.DEFINE_enum(
+_MODEL = _flags.DEFINE_string('model', None, 'Path to model file.')
+_OUTPUT = _flags.DEFINE_string('output', '', 'Output file to save.')
+_GFX = _flags.DEFINE_enum(
     'gfx', None, viewer_protocol.GFX_MODES, 'Rendering graphics mode.'
 )
-_WIDTH = flags.DEFINE_integer('width', 320, 'Width of the output image.')
-_HEIGHT = flags.DEFINE_integer('height', 240, 'Height of the output image.')
-_STEPS = flags.DEFINE_integer('steps', 1, 'Number of steps before render.')
+_WIDTH = _flags.DEFINE_integer('width', 320, 'Width of the output image.')
+_HEIGHT = _flags.DEFINE_integer('height', 240, 'Height of the output image.')
+_STEPS = _flags.DEFINE_integer('steps', 1, 'Number of steps before render.')
 
 
-def main(argv):
-  if len(argv) > 1:
-    raise app.UsageError('Too many command-line arguments.')
-  if not _MODEL.value:
-    raise ValueError('`model` flag is required.')
+def main(argv: list[str]) -> None:
+  model_path = _MODEL.value or (
+      argv[1] if len(argv) > 1 and not argv[1].startswith('--') else None
+  )
+  if not model_path:
+    raise _app.UsageError('Please provide a model path argument or --model flag.')
   if not _OUTPUT.value:
-    raise ValueError('`output flag is required.')
+    raise _app.UsageError('`output` flag is required.')
 
   try:
-    data = parser.parse(_MODEL.value)
+    data = parser.parse(model_path)
     model = data.model
   except Exception as ex:  # pylint: disable=broad-except
-    print(f'Error loading model from `{_MODEL.value}`: {ex}')
+    print(f'Error loading model from `{model_path}`: {ex}')
     sys.exit(-1)
 
   for _ in range(_STEPS.value):
@@ -73,4 +74,4 @@ def main(argv):
 
 
 if __name__ == '__main__':
-  app.run(main)
+  _app.run(main)
diff --git a/python/mujoco/experimental/studio/viewer.py b/python/mujoco/experimental/studio/viewer.py
index 35b4a525..4cda28f6 100644
--- a/python/mujoco/experimental/studio/viewer.py
+++ b/python/mujoco/experimental/studio/viewer.py
@@ -14,7 +14,7 @@
 """Interactive Studio GUI viewer for MuJoCo."""
 
 from absl import app as _app
-from absl import flags
+from absl import flags as _flags
 from mujoco.experimental.studio import launch_passive
 from mujoco.experimental.studio import messages
 from mujoco.experimental.studio import parser
@@ -24,19 +24,15 @@ from mujoco.experimental.studio import viewer_protocol
 
 vp = viewer_protocol
 
-_GFX = flags.DEFINE_enum('gfx', None, vp.GFX_MODES, 'Graphics mode.')
-_WIDTH = flags.DEFINE_integer('width', 1200, 'Width of output window.')
-_HEIGHT = flags.DEFINE_integer('height', 800, 'Height of output window.')
-_MJCF_PATH = flags.DEFINE_string('mjcf', None, 'Path to MJCF file.')
-_VIEWER = flags.DEFINE_enum_class(
-    'viewer', vp.ViewerMode.NATIVE, vp.ViewerMode, 'Viewer mode.'
+_MODEL = _flags.DEFINE_string('model', None, 'Path to model file.')
+_GFX = _flags.DEFINE_enum(
+    'gfx', None, vp.GFX_MODES, 'Graphics mode ("web" launches Web Viewer).'
 )
-_PORT = flags.DEFINE_integer(
-    'port',
-    0,
-    'Web viewer port. 0 picks the first free port starting at 8080, so '
-    'several viewers can run side by side.',
+_PORT = _flags.DEFINE_integer(
+    'port', 0, 'Web Viewer port (0 picks first free port >= 8080).'
 )
+_WIDTH = _flags.DEFINE_integer('width', 1200, 'Width of the output image.')
+_HEIGHT = _flags.DEFINE_integer('height', 800, 'Height of the output image')
 
 
 def main(argv: list[str]) -> None:
@@ -44,12 +40,11 @@ def main(argv: list[str]) -> None:
       width=_WIDTH.value,
       height=_HEIGHT.value,
       gfx=_GFX.value or '',
-      viewer_mode=_VIEWER.value,
       http_port=_PORT.value,
   )
 
   # Resolve model path, if provided.
-  model_path = _MJCF_PATH.value or (
+  model_path = _MODEL.value or (
       argv[1] if len(argv) > 1 and not argv[1].startswith('--') else None
   )
 
diff --git a/python/mujoco/experimental/studio/viewer_protocol.py b/python/mujoco/experimental/studio/viewer_protocol.py
index e6193d90..9c7c4864 100644
--- a/python/mujoco/experimental/studio/viewer_protocol.py
+++ b/python/mujoco/experimental/studio/viewer_protocol.py
@@ -33,17 +33,11 @@ GFX_MODES = (
     'opengl_software',
     'vulkan',
     'vulkan_software',
+    'web',
     'webgl',
 )
 
 
-class ViewerMode(enum.StrEnum):
-  """Determines where the viewer is rendered."""
-
-  NATIVE = 'native'
-  WEB = 'web'
-
-
 # -----------------------------------------------------------------------------
 # Viewer configuration.
 # -----------------------------------------------------------------------------
@@ -56,11 +50,8 @@ class ViewerConfig:
   title: str = ''
   width: int = 1200
   height: int = 800
-  gfx: str = ''
-  viewer_mode: ViewerMode = ViewerMode.NATIVE
-  # Web viewer only: public port. 0 picks the first free port starting at 8080,
-  # so several viewers can run side by side.
-  http_port: int = 0
+  gfx: str = ''  # Graphics mode ('web' launches Web Viewer).
+  http_port: int = 0  # Web Viewer port (0 picks first free port >= 8080).
 
 
 # Legacy message types kept for backward compatibility.
diff --git a/src/experimental/platform/hal/graphics_mode.cc b/src/experimental/platform/hal/graphics_mode.cc
index 87547e5a..c87e0cd3 100644
--- a/src/experimental/platform/hal/graphics_mode.cc
+++ b/src/experimental/platform/hal/graphics_mode.cc
@@ -74,7 +74,7 @@ GraphicsMode GraphicsModeFromString(std::string_view str,
     return GraphicsMode::FilamentVulkan;
   } else if (str == "vulkan_software") {
     return GraphicsMode::FilamentVulkanSoftware;
-  } else if (str == "webgl") {
+  } else if (str == "web" || str == "webgl") {
     return GraphicsMode::FilamentWebGl;
   } else if (str == "opengl_headless") {
     return GraphicsMode::FilamentOpenGlHeadless;