Isaac Sim Remote

Execute Python inside a running Isaac Sim via the isaacsim.code_editor.python_server TCP socket.

Related: debug-with-local-kit (when behavior depends on a Kit-from-source build), profile-isaac-sim (to attach Tracy to the running process), isaac-sim-validator (final QA gate on any rendered output).

Upstream isaac-sim-ui (menu/widget OmniUIQuery automation) and isaac-sim-recording (cursor tracking, tutorial video capture) are not imported. The inline UI patterns here (Play-button click via OmniUIQuery, full-app vs viewport screenshots) cover the common cases.

Launching Isaac Sim

cd _build/linux-x86_64/release

# Headless — supports all features: code execution, viewport screenshots,
# full-app screenshots, menu clicks, and widget interaction
bash isaac-sim.sh --no-window --no-ros-env \
    --enable isaacsim.code_editor.python_server

# With display (optional — only needed if you want to visually observe the UI)
DISPLAY=:99 bash isaac-sim.sh --no-ros-env \
    --enable isaacsim.code_editor.python_server

# With --reset-user to clear persistent user settings (recommended for clean state)
DISPLAY=:99 bash isaac-sim.sh --reset-user --no-ros-env \
    --enable isaacsim.code_editor.python_server

Wait for app ready in the output before sending commands. The TCP server listens on 127.0.0.1:8226.

Extension enable flags (important):

• Use --enable isaacsim.code_editor.python_server — this is the only way to enable it.
• --/exts/isaacsim.code_editor.python_server/enabled=true does NOT work. That syntax sets a carb setting, not an extension enable flag. The python_server extension is not enabled by default in the app .kit file, so it must be explicitly enabled via --enable.
• The same applies to isaacsim.test.utils and any other extension not in the default app config.

Other notes:

• Full-app screenshots require a display (DISPLAY env var). Viewport screenshots work headless.
• Use --reset-user when settings seem stale (wrong asset root, unexpected defaults).

Verifying the server started

After launch, verify the TCP port is open before sending commands:

# Wait for port 8226 to open (poll every 2s, timeout 120s)
for i in $(seq 1 60); do
    nc -z 127.0.0.1 8226 2>/dev/null && echo "Port open" && break
    sleep 2
done

# Or check the log for the extension loading
grep "python_server" /tmp/isaac_sim.log

If the port never opens, check that isaacsim.code_editor.python_server appears in the startup log. If it doesn't, the --enable flag was not passed correctly.

Enabling additional extensions

bash isaac-sim.sh --no-window --no-ros-env \
    --enable isaacsim.code_editor.python_server \
    --enable isaacsim.test.utils \
    --enable isaacsim.sensors.experimental.rtx

Health Check

Verify the server is running and get environment info:

python scripts/isaacsim_send.py --file scripts/health_check.py

Reports: Isaac Sim version, asset root, stage state, timeline, display, enabled extensions count.

Asset Root Configuration

Isaac Sim assets (robots, environments) require either a Nucleus server or S3 cloud fallback. If Nucleus is unavailable, configure S3 assets:

python scripts/isaacsim_send.py --file scripts/set_asset_root.py --arg asset_root=staging

Asset servers: staging (S3, Isaac 6.0 paths), production (S3, Isaac 5.0 paths), nucleus (default).

Sending Code

Use scripts/isaacsim_send.py:

# Inline code
python scripts/isaacsim_send.py 'print("hello")'

# From a .py file with injected variables
python scripts/isaacsim_send.py --file scripts/app_screenshot.py \
    --arg output_path=/tmp/shot.png

# Custom timeout
python scripts/isaacsim_send.py --timeout 120 'long_running()'

# Raw JSON output
python scripts/isaacsim_send.py --raw 'print("hello")'

Response format

{"status": "ok", "output": "hello", "result": null}
{"status": "error", "output": "", "ename": "NameError", "evalue": "name 'x' is not defined", "traceback": ["..."]}

Exit codes: 0 = ok, 1 = error or connection failure.

Async Code

The server supports top-level await:

python scripts/isaacsim_send.py '
import isaacsim.core.experimental.utils.stage as stage_utils
await stage_utils.create_new_stage_async(template="empty")
'

State Persistence & Named Contexts

The server supports named execution contexts — each is an independent globals dict. Variables set in --context A are invisible in --context B. The default context (no --context flag) is a shared namespace where variables persist across calls.

# Default context — shared globals, variables persist
python scripts/isaacsim_send.py 'MY_PATHS = ["/World/A"]'
python scripts/isaacsim_send.py 'print(MY_PATHS)'  # still available

# Named contexts — fully isolated
python scripts/isaacsim_send.py --context rec 'fc = 0; frames = []'
python scripts/isaacsim_send.py --context browser 'detail = None; cat = None'
# rec and browser are fully isolated from each other and from the default context

When to use named contexts:

• Recording — frame counters, cursor state, output dir
• Browser automation — widget references, button positions
• Scene setup — stage references, prim paths
• Any multi-tool workflow where globals must not leak between tools

Delete a context when done:

python scripts/isaacsim_send.py --introspect delete_context --context rec

JSON Envelope Protocol

The client supports a JSON envelope for advanced features. It auto-detects when to use the envelope (any of --context, --fire-and-forget, --execution-timeout, or --args-json triggers it). Raw Python source still works for simple calls.

# Named context with file
python scripts/isaacsim_send.py --context recording --file setup.py

# Per-request server-side timeout (kills async code cleanly)
python scripts/isaacsim_send.py --execution-timeout 30 'await long_operation()'

# Inject args via JSON (type-safe, no string parsing)
python scripts/isaacsim_send.py --args-json '{"x": 42, "name": "robot"}' 'print(f"{name}={x}")'

# Fire-and-forget — immediate ACK, code runs in background
python scripts/isaacsim_send.py --fire-and-forget 'heavy_computation()'
# Returns: Task submitted. task_id: <uuid>

# Query background task result
python scripts/isaacsim_send.py --introspect task <task_id>

# Server introspection
python scripts/isaacsim_send.py --introspect status    # uptime, connections, tasks
python scripts/isaacsim_send.py --introspect contexts   # list all named contexts
python scripts/isaacsim_send.py --introspect tasks      # list completed background tasks

Execution Timeouts

Async code is cancelled cleanly via asyncio.wait_for(). Sync code uses a background watchdog — the code finishes running but the client gets a TimeoutError response.

# This returns TimeoutError after 5s (the sleep(100) is cancelled)
python scripts/isaacsim_send.py --execution-timeout 5 'import asyncio; await asyncio.sleep(100)'

Fire-and-Forget

For deferred UI clicks, background data loading, or any operation where you don't need to wait for the result:

ack=$(python scripts/isaacsim_send.py --raw --fire-and-forget 'load_large_usd()')
task_id=$(echo "$ack" | python3 -c "import sys,json; print(json.load(sys.stdin)['task_id'])")

# Later...
python scripts/isaacsim_send.py --introspect task "$task_id"

Up to 100 completed results are retained (FIFO eviction).

Screenshots

# Full-app (UI chrome + viewport, requires DISPLAY)
python scripts/isaacsim_send.py --file scripts/app_screenshot.py --arg output_path=/tmp/full.png

# Viewport only (3D render, works headless)
python scripts/isaacsim_send.py --file scripts/viewport_screenshot.py --arg output_path=/tmp/vp.png

# Annotator data (depth, normals, segmentation)
python scripts/isaacsim_send.py --file scripts/capture_annotator.py \
    --arg annotator=distance_to_camera --arg output_path=/tmp/depth.npy

Stage Management

# Create new empty stage
python scripts/isaacsim_send.py --file scripts/open_stage.py --arg action=new

# Open a USD file
python scripts/isaacsim_send.py --timeout 120 --file scripts/open_stage.py \
    --arg usd_path=/path/to/scene.usd

# Save stage
python scripts/isaacsim_send.py --file scripts/open_stage.py \
    --arg action=save --arg usd_path=/tmp/saved.usd

# Stage info
python scripts/isaacsim_send.py --file scripts/open_stage.py --arg action=info

Scene Inspection

# Stage tree
python scripts/isaacsim_send.py --file scripts/stage_info.py

# Detailed prim view
python scripts/isaacsim_send.py --file scripts/stage_info.py --arg prim_path=/World/Cube

# Filter by type
python scripts/isaacsim_send.py --file scripts/stage_info.py --arg filter_type=Camera

# List/read/set prim attributes
python scripts/isaacsim_send.py --file scripts/prim_properties.py \
    --arg prim_path=/World/Cube --arg action=list

# Select prims
python scripts/isaacsim_send.py --file scripts/select_prim.py \
    --arg action=set --arg prim_path=/World/Cube

Transform Control

python scripts/isaacsim_send.py --file scripts/prim_transform.py \
    --arg prim_path=/World/Cube --arg action=set --arg "position=3,0,1"

Camera Control

# Get pose
python scripts/isaacsim_send.py --file scripts/camera_control.py

# Set position + look-at target
python scripts/isaacsim_send.py --file scripts/camera_control.py \
    --arg action=set --arg "position=1.5,1.5,1.2" --arg "target=0,0,0.5"

# List cameras
python scripts/isaacsim_send.py --file scripts/camera_control.py --arg action=list_cameras

Inline camera control (recommended — handles viewport COI and camera controller correctly):

from isaacsim.core.rendering_manager import ViewportManager
import isaacsim.core.experimental.utils.app as app_utils

ViewportManager.set_camera_view("/OmniverseKit_Persp", eye=[1.5, 1.5, 1.0], target=[0.0, 0.0, 0.4])
app_utils.update_app(steps=30)

Simulation Control

python scripts/isaacsim_send.py --file scripts/simulation_control.py --arg action=play
python scripts/isaacsim_send.py --file scripts/simulation_control.py --arg action=step --arg num_steps=100
python scripts/isaacsim_send.py --file scripts/simulation_control.py --arg action=stop

Playing simulation via UI (real click on Play button)

When you need a real button click for recording or testing (not just API):

import omni.ui as ui
from omni.ui_query import OmniUIQuery
from omni.kit.ui_test import Vec2, emulate_mouse_move_and_click

# Find the Play button in the toolbar
toolbar_win = next(w for w in ui.Workspace.get_windows() if w.title == "Main ToolBar")
for path in OmniUIQuery.get_window_widget_paths(toolbar_win):
    widget = OmniUIQuery.find_widget(path)
    if widget and getattr(widget, "name", "") == "play":
        px = widget.screen_position_x + widget.computed_width / 2
        py = widget.screen_position_y + widget.computed_height / 2
        break

# Direct click — toolbar buttons do NOT need deferred clicks
await emulate_mouse_move_and_click(Vec2(px, py))
await app_utils.update_app_async(steps=30)
assert app_utils.is_playing(), "Play button click failed"

Note: Toolbar buttons (Play, Pause, Stop) use direct clicks. Browser buttons (extension/example browsers) need deferred clicks via omni.kit.ui_test. See references/pitfalls.md for the deferred-click pattern.

Command Execution

# List commands
python scripts/isaacsim_send.py --file scripts/execute_command.py --arg action=list --arg filter=Physics

# Execute
python scripts/isaacsim_send.py --file scripts/execute_command.py \
    --arg command_name=CreateMeshPrimWithDefaultXform --arg 'kwargs={"prim_type":"Cone"}'

Console Log

python scripts/isaacsim_send.py --file scripts/console_log.py                    # tail
python scripts/isaacsim_send.py --file scripts/console_log.py --arg action=errors  # errors only
python scripts/isaacsim_send.py --file scripts/console_log.py --arg action=search --arg query=PhysX

Moving Prims (Setting World Pose)

Do NOT use xform.set_world_pose() — it raises NotImplementedError.

Before simulation starts, use XformPrim:

import numpy as np
from isaacsim.core.experimental.prims import XformPrim

target = XformPrim(paths="/World/TargetCube")
target.set_world_poses(positions=np.array([[0.3, 0.2, 0.5]]))

During simulation (after play()), XformPrim.set_world_poses may fail with RuntimeError: Item indexing is not supported on wp.array objects because warp arrays replace numpy arrays at runtime. Use raw USD instead:

from pxr import UsdGeom, Gf
import omni.usd

stage = omni.usd.get_context().get_stage()
prim = stage.GetPrimAtPath("/World/TargetCube")
xformable = UsdGeom.Xformable(prim)
for op in xformable.GetOrderedXformOps():
    if op.GetOpType() == UsdGeom.XformOp.TypeTranslate:
        op.Set(Gf.Vec3d(0.3, 0.2, 0.5))
        break

Reading works fine with xform utils (both before and during simulation):

from isaacsim.core.experimental.utils import xform
pos, rot = xform.get_world_pose("/World/TargetCube")

Common Patterns

Create a new stage with objects

import numpy as np
from isaacsim.core.experimental.objects import Cube, DomeLight
import isaacsim.core.experimental.utils.stage as stage_utils

await stage_utils.create_new_stage_async(template="empty")
stage_utils.define_prim("/World", "Xform")
DomeLight("/World/DomeLight").set_intensities(np.array([3000.0]))
Cube("/World/RedCube", sizes=1.0, colors="red", positions=(0, 0, 0.5))

Step the renderer / simulation

Prefer await update_app_async() over update_app() when running code that uses await (which includes all python_server scripts with top-level await). The sync update_app() pumps the event loop from inside an asyncio Task, which causes "Cannot enter into task" errors in other extensions. The async version yields properly.

import isaacsim.core.experimental.utils.app as app_utils

# Async (preferred — yields to event loop, no reentrancy errors)
await app_utils.update_app_async(steps=120)  # Render frames (warm-up)
app_utils.play()
await app_utils.update_app_async(steps=100)
app_utils.stop()

# Sync (use in non-async contexts only, e.g. tests, standalone scripts)
app_utils.update_app(steps=120)

Key APIs

Isaac Sim APIs (preferred):

• isaacsim.core.experimental.utils.stage — stage ops
• isaacsim.core.experimental.utils.app — update_app(), play(), stop(), enable_extension()
• isaacsim.core.experimental.utils.prim — prim queries
• isaacsim.core.experimental.objects — Cube, Sphere, DomeLight, GroundPlane
• isaacsim.core.experimental.prims — XformPrim, RigidPrim, GeomPrim
• isaacsim.storage.native — get_assets_root_path()

Kit APIs:

• omni.kit.renderer.capture — capture_next_frame_swapchain() for full-app capture
• omni.kit.actions.core — get_action_registry() for registered actions

See references/api-reference.md for full details. See references/pitfalls.md for common issues.

Important Notes

• Lighting in headless mode: No lights = black image. Always add a DomeLight with intensity 1000–5000.
• Renderer warm-up: After new stage, call app_utils.update_app(steps=120) before rendering.
• Connection errors: Ensure Isaac Sim shows app ready and python_server is --enabled.
• Server hangs: Crashed examples can wedge the server. Restart Isaac Sim. Use health_check.py to verify.
• Assets not found: Configure S3 fallback with set_asset_root.py.