From 6c78c98418f2958f8363ee6e61297f24c9f9be8a Mon Sep 17 00:00:00 2001
From: Matija Kecman <matijak@google.com>
Date: Fri, 31 Jul 2026 08:06:33 -0700
Subject: [PATCH] MuJoCo Web Viewer: update code to support the web viewer

PiperOrigin-RevId: 957147035
Change-Id: Ibe5d68b2654a7faac23c297d4f492929209c078d
---
 python/mujoco/experimental/studio/launch_passive.py | 6 +++---
 python/mujoco/experimental/studio/viewer.py         | 7 +++++++
 python/mujoco/experimental/studio/viewer_app.py     | 3 ++-
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/python/mujoco/experimental/studio/launch_passive.py b/python/mujoco/experimental/studio/launch_passive.py
index 215c940f..708e75f1 100644
--- a/python/mujoco/experimental/studio/launch_passive.py
+++ b/python/mujoco/experimental/studio/launch_passive.py
@@ -93,9 +93,7 @@ def run_viewer_target(
 
   Raises:
     ValueError: If the viewer mode requested in config is unknown.
-    NotImplementedError: If web mode is requested.
   """
-
   if config.viewer_mode == viewer_protocol.ViewerMode.NATIVE:
     from mujoco.experimental.studio import native_viewer  # pylint: disable=g-import-not-at-top
 
@@ -103,7 +101,9 @@ def run_viewer_target(
         config, viewer_endpoint, handlers=handlers
     )
   elif config.viewer_mode == viewer_protocol.ViewerMode.WEB:
-    raise NotImplementedError('Web viewer not implemented yet')
+    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}')
 
diff --git a/python/mujoco/experimental/studio/viewer.py b/python/mujoco/experimental/studio/viewer.py
index e774105d..35b4a525 100644
--- a/python/mujoco/experimental/studio/viewer.py
+++ b/python/mujoco/experimental/studio/viewer.py
@@ -31,6 +31,12 @@ _MJCF_PATH = flags.DEFINE_string('mjcf', None, 'Path to MJCF file.')
 _VIEWER = flags.DEFINE_enum_class(
     'viewer', vp.ViewerMode.NATIVE, vp.ViewerMode, 'Viewer mode.'
 )
+_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.',
+)
 
 
 def main(argv: list[str]) -> None:
@@ -39,6 +45,7 @@ def main(argv: list[str]) -> None:
       height=_HEIGHT.value,
       gfx=_GFX.value or '',
       viewer_mode=_VIEWER.value,
+      http_port=_PORT.value,
   )
 
   # Resolve model path, if provided.
diff --git a/python/mujoco/experimental/studio/viewer_app.py b/python/mujoco/experimental/studio/viewer_app.py
index e294c3ab..d65c307d 100644
--- a/python/mujoco/experimental/studio/viewer_app.py
+++ b/python/mujoco/experimental/studio/viewer_app.py
@@ -15,6 +15,7 @@
 
 import copy
 import dataclasses
+
 import mujoco
 from mujoco.experimental.studio import messages
 from mujoco.experimental.studio import parser
@@ -355,7 +356,7 @@ class ViewerApp:
       paused = (
           self.step_control_state.get_pause_state() != sim.PauseState.UNPAUSED
       )
-      ux.stats_gui(self.model, self.data, paused, 0.0)
+      ux.info_gui(self.model, self.data, paused, 0.0)
       imgui.End()
 
     # -- Status bar -----------------------------------------------------------