Add Kit test markers and a shared launch_kit() helper

Kit-dependence is currently a property of importing a test file: 156 test
modules construct AppLauncher at module scope, so Isaac Sim boots during
pytest collection. Because nothing declares that dependency, tools/conftest.py
has to run every test file in its own subprocess, paying Kit startup once per
file.

Introduce the two pieces needed to change that:

launch_kit() is an idempotent module-scope replacement for AppLauncher. The
first test module in a process boots Kit; later modules receive the running
app, so a pytest run covering several files pays startup once. It raises
rather than silently returning a mismatched app when a file asks for cameras
after a camera-less boot.

The kit / kit_cameras / kitless markers let a file declare which launch
configuration it needs, so files that can share a process can be grouped
without importing them. kit_solo opts a file out of any such grouping.

test_kit_marker_contract.py keeps the markers from drifting: it checks by AST
that a file's declaration matches what it does at module scope. The checks are
AST-based rather than text-based because several kit-free files mention
AppLauncher only in a docstring saying they do not use it. Files are not yet
required to carry a marker; _ENFORCED_ROOTS is empty and grows per package as
files are migrated.

No test file changes behaviour: nothing is marked kit or kitless yet, and no
file calls launch_kit() yet.

The guard found one pre-existing bug on its first run. test_operational_space
assigned pytestmark twice, and the second assignment discarded arm_ci, so the
file had been excluded from the ARM CI lane. Merged into a single list.

Author: mataylor-nvidia

pyproject.toml

@@ -338,6 +338,11 @@ markers = [
     "benchmark: test covers the Isaac Lab benchmark framework and infrastructure",
     "rendering: test exercises the rendering / camera / visualizer pipeline",
     "smoke: tests for core installation, task, and RL functionality",
+    "kit: test file needs a booted headless Kit app; it calls isaaclab.test.launch.launch_kit() at module scope rather than constructing AppLauncher",
+    "kit_cameras: like `kit`, but the app is booted with cameras enabled via launch_kit(cameras=True)",
+    "kitless: test file runs without Kit; no AppLauncher and no module-scope import of omni/carb/isaacsim",
+    "kit_solo: keep this file in its own process; it is never grouped with other files",
+    "newton_ci: mark test to run in the Newton CI lane",
 ]
 
 # Add pypi.nvidia.com so that `uv pip install isaaclab[isaacsim]` works without --extra-index-url.

source/isaaclab/changelog.d/mataylor-kit-test-markers.rst

@@ -0,0 +1,15 @@
+Added
+^^^^^
+
+* Added :func:`~isaaclab.test.launch.launch_kit` so test modules can share one Kit app per
+  pytest process instead of each launching their own. It is idempotent: the first module to
+  call it boots Kit and later modules receive the running app.
+* Added the ``kit``, ``kit_cameras``, ``kitless``, and ``kit_solo`` pytest markers so a test
+  file can declare its Kit launch configuration, plus a test that checks each file's markers
+  against what it actually does at module scope.
+
+Fixed
+^^^^^
+
+* Fixed ``test_operational_space.py`` assigning ``pytestmark`` twice, which silently dropped
+  its ``arm_ci`` marker and kept the file out of the ARM CI lane.

source/isaaclab/isaaclab/test/launch.py

@@ -0,0 +1,84 @@
+# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Shared Kit launch helper for Isaac Lab tests.
+
+Test modules that need Isaac Sim call :func:`launch_kit` at module scope in place of
+constructing :class:`~isaaclab.app.AppLauncher` directly::
+
+    from isaaclab.test.launch import launch_kit
+
+    launch_kit()  # or launch_kit(cameras=True)
+
+The call must stay at module scope: a test module's own imports (``pxr``, ``omni``,
+``isaaclab_physx``, ...) run during pytest collection, before any fixture executes, so Kit
+must already be running by then.
+
+:func:`launch_kit` is idempotent within a process. The first test module to call it boots
+Kit; every later module gets the running app back. A pytest process covering several test
+files therefore pays Kit startup once rather than once per file.
+
+Declare the matching marker on the module so the test runner can group files that share a
+launch configuration into one process::
+
+    pytestmark = pytest.mark.kit  # launch_kit()
+    pytestmark = pytest.mark.kit_cameras  # launch_kit(cameras=True)
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+_app: Any = None
+"""The Kit application booted by :func:`launch_kit`, or None before the first call."""
+
+_cameras: bool = False
+"""Whether :attr:`_app` was booted with camera and render extensions enabled."""
+
+
+def launch_kit(*, cameras: bool = False) -> Any:
+    """Boot the shared Kit app for this process, or return the one already running.
+
+    Args:
+        cameras: Whether the app must be booted with camera and render extensions enabled.
+            Passed through to :paramref:`~isaaclab.app.AppLauncher.enable_cameras`.
+
+    Returns:
+        The running ``SimulationApp``.
+
+    Raises:
+        RuntimeError: If a camera-enabled app is requested but Kit is already running in
+            this process without cameras, or if Kit was started by something other than
+            this function. Both mean the test files sharing this process do not share a
+            launch configuration and must be split across processes.
+    """
+    global _app, _cameras
+
+    if _app is not None:
+        if cameras and not _cameras:
+            raise RuntimeError(
+                "launch_kit(cameras=True) was called, but Kit is already running in this process"
+                " without cameras. Camera extensions cannot be enabled after startup. Mark this"
+                " file `pytest.mark.kit_cameras` so it is grouped with other camera tests instead"
+                " of with plain `pytest.mark.kit` files."
+            )
+        return _app
+
+    from isaaclab.utils import has_kit
+
+    if has_kit():
+        raise RuntimeError(
+            "Kit is already running but was not started by launch_kit(), so its launch"
+            " configuration is unknown. Another test file in this process still constructs"
+            " AppLauncher directly; run that file in its own process."
+        )
+
+    from isaaclab.app import AppLauncher
+
+    from .utils import resolve_test_sim_device
+
+    _app = AppLauncher(headless=True, enable_cameras=cameras, device=resolve_test_sim_device()).app
+    _cameras = cameras
+    return _app

source/isaaclab/test/controllers/test_operational_space.py

@@ -16,8 +16,6 @@
 import torch
 from flaky import flaky
 
-pytestmark = pytest.mark.arm_ci
-
 import isaaclab.envs.mdp as mdp
 import isaaclab.sim as sim_utils
 from isaaclab import cloner
@@ -51,7 +49,7 @@
 
 from isaaclab_assets import FRANKA_PANDA_CFG, G1_29DOF_CFG  # isort:skip
 
-pytestmark = pytest.mark.integration
+pytestmark = [pytest.mark.arm_ci, pytest.mark.integration]
 
 
 @pytest.fixture