[Backport release/3.0.0] Centralize shared physics preset ownership (#7312)

# Description

Backports #7301 to `release/3.0.0` by cherry-picking the canonical
merged commit `f86b4e1ad66e637e7770a727e181ffe150a2077b`.

This centralizes backend physics presets at the task-family composition
roots:

- Kuka Allegro reuses the shared lift physics configuration.
- SO-101 reuses the shared stack physics configuration.
- Flat velocity environments mutate robot-specific MJWarp values
directly instead of defining preset subclasses.
- Newton MJWarp velocity environments use two shared physics substeps,
with no robot-specific substep overrides.
- The corresponding Anymal-D Newton visualizer goldens and changelog
fragments are included.

The cherry-pick applied without conflicts, and all 21 affected files are
byte-for-byte identical to the merged #7301 versions.

## Validation

- `uv run --extra test --frozen python -m pytest -q
source/isaaclab_tasks/test/core/test_velocity_newton_cfg.py
source/isaaclab_tasks/test/core/test_lift_kuka_ovphysx_presets.py
source/isaaclab_tasks/test/core/test_lift_env_cfg.py` — 8 passed.
- Direct construction audit — all 10 affected Newton velocity configs
use `num_substeps=2`; SO-101 and Kuka inherit the intended shared
physics values.
- Structural audit — no `PhysicsCfg(RoughPhysicsCfg)`,
`KukaAllegroPhysicsCfg`, or `SO101StackPhysicsCfg` remains in task code;
robot-specific velocity configs do not assign `.num_substeps`.
- `uv run --frozen isaaclab -f` — all hooks passed, including changelog
and Git LFS checks.

Author: ooctipus

source/isaaclab_tasks/changelog.d/shared-physics-preset-ownership.major.rst

@@ -0,0 +1,5 @@
+Changed
+^^^^^^^
+
+* **Breaking:** Changed Newton MJWarp velocity environments to use two physics substeps from their
+  shared family configuration. Robot-specific velocity configs no longer override the substep count.

source/isaaclab_tasks/isaaclab_tasks/contrib/stack/config/so101/stack_joint_pos_env_cfg.py

@@ -4,12 +4,10 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
 from isaaclab.assets import ArticulationCfg, RigidObjectCfg
-from isaaclab.physics import PhysxAutoCfg
 from isaaclab.utils.configclass import configclass
 
 from isaaclab_tasks.contrib.stack import mdp
 from isaaclab_tasks.contrib.stack.stack_env_cfg import (
-    PhysicsCfg,
     StackEnvCfg,
     StackEventCfg,
     apply_default_semantics,
@@ -52,21 +50,6 @@
 _SO101_BASE_SEAT_ROT = (0.0, 0.0, 0.70710678, 0.70710678)
 
 
-@configclass
-class SO101StackPhysicsCfg(PhysicsCfg):
-    """Physics presets for the SO-101 stack tasks.
-
-    Extends the stack-family presets with
-    :attr:`~isaaclab_physx.physics.PhysxCfg.solve_articulation_contact_last` so contacts
-    are solved after the articulation position drive and can stall the closing jaw at the
-    object surface instead of letting it tunnel through grasped objects.
-    """
-
-    isaacsim_physx = PhysicsCfg().isaacsim_physx.replace(solve_articulation_contact_last=True)
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx)
-    default = isaacsim_physx
-
-
 @configclass
 class SO101CubeStackEnvCfg(StackEnvCfg):
     """Configuration for the SO-101 Cube Stack Environment (joint-position control).
@@ -144,7 +127,3 @@ def __post_init__(self):
             ],
             marker_scale=(0.05, 0.05, 0.05),
         )
-
-        # simulation settings: solve finger contacts after the position drive so they can
-        # stall the closing jaw at the object surface (see SO101StackPhysicsCfg).
-        self.sim.physics = SO101StackPhysicsCfg()

source/isaaclab_tasks/isaaclab_tasks/contrib/stack/stack_env_cfg.py

@@ -296,6 +296,8 @@ class PhysicsCfg(PresetCfg):
         gpu_found_lost_aggregate_pairs_capacity=1024 * 1024 * 4,
         gpu_total_aggregate_pairs_capacity=2**21,
         friction_correlation_distance=0.00625,
+        # Let object contacts stall position-driven grippers before they tunnel through a grasp.
+        solve_articulation_contact_last=True,
     )
     newton_mjwarp = NewtonCfg(
         solver_cfg=MJWarpSolverCfg(

source/isaaclab_tasks/isaaclab_tasks/contrib/velocity/config/a1/flat_env_cfg.py

@@ -3,46 +3,21 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
-from isaaclab_newton.physics import KaminoPADMMSolverCfg, MJWarpSolverCfg, NewtonCfg
-from isaaclab_ov.physics import OvPhysxCfg
-from isaaclab_physx.physics import PhysxCfg
-
-from isaaclab.physics import PhysxAutoCfg
-from isaaclab.sim import SimulationCfg
 from isaaclab.utils.configclass import configclass
 
-from isaaclab_tasks.utils import PresetCfg
-
 from .rough_env_cfg import UnitreeA1RoughEnvCfg
 
 
-@configclass
-class PhysicsCfg(PresetCfg):
-    isaacsim_physx = PhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    ovphysx = OvPhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx, ovphysx=ovphysx)
-    newton_mjwarp = NewtonCfg(
-        solver_cfg=MJWarpSolverCfg(
-            njmax=60,
-            nconmax=30,
-            cone="pyramidal",
-            impratio=1,
-            integrator="implicitfast",
-        ),
-        num_substeps=1,
-        debug_mode=False,
-    )
-    newton_kamino = NewtonCfg(solver_cfg=KaminoPADMMSolverCfg(max_contacts_per_world=64))
-    default = isaacsim_physx
-
-
 @configclass
 class UnitreeA1FlatEnvCfg(UnitreeA1RoughEnvCfg):
-    sim: SimulationCfg = SimulationCfg(physics=PhysicsCfg())
-
     def __post_init__(self):
         super().__post_init__()
 
+        # physics
+        newton_mjwarp = self.sim.physics.newton_mjwarp
+        newton_mjwarp.solver_cfg.njmax = 60
+        newton_mjwarp.solver_cfg.nconmax = 30
+        self.sim.physics.default = self.sim.physics.isaacsim_physx
         # scene
         self.scene.terrain.terrain_type = "plane"
         self.scene.terrain.terrain_generator = None

source/isaaclab_tasks/isaaclab_tasks/contrib/velocity/config/anymal_b/flat_env_cfg.py

@@ -3,46 +3,23 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
-from isaaclab_newton.physics import KaminoPADMMSolverCfg, MJWarpSolverCfg, NewtonCfg
-from isaaclab_ov.physics import OvPhysxCfg
-from isaaclab_physx.physics import PhysxCfg
-
-from isaaclab.physics import PhysxAutoCfg
-from isaaclab.sim import SimulationCfg
 from isaaclab.utils.configclass import configclass
 
-from isaaclab_tasks.utils import PresetCfg
-
 from .rough_env_cfg import AnymalBRoughEnvCfg
 
 
-@configclass
-class PhysicsCfg(PresetCfg):
-    isaacsim_physx = PhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    ovphysx = OvPhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx, ovphysx=ovphysx)
-    newton_mjwarp = NewtonCfg(
-        solver_cfg=MJWarpSolverCfg(
-            njmax=75,
-            nconmax=15,
-            cone="elliptic",
-            impratio=100,
-            integrator="implicitfast",
-        ),
-        num_substeps=1,
-        debug_mode=False,
-    )
-    newton_kamino = NewtonCfg(solver_cfg=KaminoPADMMSolverCfg(max_contacts_per_world=64))
-    default = isaacsim_physx
-
-
 @configclass
 class AnymalBFlatEnvCfg(AnymalBRoughEnvCfg):
-    sim: SimulationCfg = SimulationCfg(physics=PhysicsCfg())
-
     def __post_init__(self):
         super().__post_init__()
 
+        # physics
+        newton_mjwarp = self.sim.physics.newton_mjwarp
+        newton_mjwarp.solver_cfg.njmax = 75
+        newton_mjwarp.solver_cfg.nconmax = 15
+        newton_mjwarp.solver_cfg.cone = "elliptic"
+        newton_mjwarp.solver_cfg.impratio = 100.0
+        self.sim.physics.default = self.sim.physics.isaacsim_physx
         # scene
         self.scene.terrain.terrain_type = "plane"
         self.scene.terrain.terrain_generator = None

source/isaaclab_tasks/isaaclab_tasks/contrib/velocity/config/anymal_c/flat_env_cfg.py

@@ -3,46 +3,23 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
-from isaaclab_newton.physics import KaminoPADMMSolverCfg, MJWarpSolverCfg, NewtonCfg
-from isaaclab_ov.physics import OvPhysxCfg
-from isaaclab_physx.physics import PhysxCfg
-
-from isaaclab.physics import PhysxAutoCfg
-from isaaclab.sim import SimulationCfg
 from isaaclab.utils.configclass import configclass
 
-from isaaclab_tasks.utils import PresetCfg
-
 from .rough_env_cfg import AnymalCRoughEnvCfg
 
 
-@configclass
-class PhysicsCfg(PresetCfg):
-    isaacsim_physx = PhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    ovphysx = OvPhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx, ovphysx=ovphysx)
-    newton_mjwarp = NewtonCfg(
-        solver_cfg=MJWarpSolverCfg(
-            njmax=120,
-            nconmax=15,
-            cone="elliptic",
-            impratio=100,
-            integrator="implicitfast",
-        ),
-        num_substeps=1,
-        debug_mode=False,
-    )
-    newton_kamino = NewtonCfg(solver_cfg=KaminoPADMMSolverCfg(max_contacts_per_world=64))
-    default = isaacsim_physx
-
-
 @configclass
 class AnymalCFlatEnvCfg(AnymalCRoughEnvCfg):
-    sim: SimulationCfg = SimulationCfg(physics=PhysicsCfg())
-
     def __post_init__(self):
         super().__post_init__()
 
+        # physics
+        newton_mjwarp = self.sim.physics.newton_mjwarp
+        newton_mjwarp.solver_cfg.njmax = 120
+        newton_mjwarp.solver_cfg.nconmax = 15
+        newton_mjwarp.solver_cfg.cone = "elliptic"
+        newton_mjwarp.solver_cfg.impratio = 100.0
+        self.sim.physics.default = self.sim.physics.isaacsim_physx
         # scene
         self.scene.terrain.terrain_type = "plane"
         self.scene.terrain.terrain_generator = None

source/isaaclab_tasks/isaaclab_tasks/contrib/velocity/config/go1/flat_env_cfg.py

@@ -3,46 +3,21 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
-from isaaclab_newton.physics import KaminoPADMMSolverCfg, MJWarpSolverCfg, NewtonCfg
-from isaaclab_ov.physics import OvPhysxCfg
-from isaaclab_physx.physics import PhysxCfg
-
-from isaaclab.physics import PhysxAutoCfg
-from isaaclab.sim import SimulationCfg
 from isaaclab.utils.configclass import configclass
 
-from isaaclab_tasks.utils import PresetCfg
-
 from .rough_env_cfg import UnitreeGo1RoughEnvCfg
 
 
-@configclass
-class PhysicsCfg(PresetCfg):
-    isaacsim_physx = PhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    ovphysx = OvPhysxCfg(gpu_max_rigid_patch_count=10 * 2**15)
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx, ovphysx=ovphysx)
-    newton_mjwarp = NewtonCfg(
-        solver_cfg=MJWarpSolverCfg(
-            njmax=60,
-            nconmax=25,
-            cone="pyramidal",
-            impratio=1,
-            integrator="implicitfast",
-        ),
-        num_substeps=1,
-        debug_mode=False,
-    )
-    newton_kamino = NewtonCfg(solver_cfg=KaminoPADMMSolverCfg(max_contacts_per_world=64))
-    default = isaacsim_physx
-
-
 @configclass
 class UnitreeGo1FlatEnvCfg(UnitreeGo1RoughEnvCfg):
-    sim: SimulationCfg = SimulationCfg(physics=PhysicsCfg())
-
     def __post_init__(self):
         super().__post_init__()
 
+        # physics
+        newton_mjwarp = self.sim.physics.newton_mjwarp
+        newton_mjwarp.solver_cfg.njmax = 60
+        newton_mjwarp.solver_cfg.nconmax = 25
+        self.sim.physics.default = self.sim.physics.isaacsim_physx
         # scene
         self.scene.terrain.terrain_type = "plane"
         self.scene.terrain.terrain_generator = None

source/isaaclab_tasks/isaaclab_tasks/contrib/velocity/config/spot/flat_env_cfg.py

@@ -49,7 +49,7 @@ class PhysicsCfg(PresetCfg):
             use_mujoco_contacts=False,
         ),
         collision_cfg=NewtonCollisionPipelineCfg(max_triangle_pairs=2_500_000),
-        num_substeps=1,
+        num_substeps=2,
         debug_mode=False,
         default_shape_cfg=NewtonShapeCfg(margin=0.01),
     )

source/isaaclab_tasks/isaaclab_tasks/core/lift/config/kuka_allegro/kuka_allegro_env_cfg.py

@@ -3,13 +3,10 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
-from isaaclab_ov.physics import OvPhysxCfg
-
 from isaaclab.assets import ArticulationCfg
 from isaaclab.managers import EventTermCfg as EventTerm
 from isaaclab.managers import RewardTermCfg as RewTerm
 from isaaclab.managers import SceneEntityCfg
-from isaaclab.physics import PhysxAutoCfg
 from isaaclab.sensors import CameraCfg, ContactSensorCfg
 from isaaclab.utils.configclass import configclass
 
@@ -24,20 +21,6 @@
 FINGER_SENSORS = [f"{name}_object_s" for name in FINGERTIP_LIST if name != "thumb_link_3"]
 
 
-@configclass
-class KukaAllegroPhysicsCfg(lift.PhysicsCfg):
-    """Physics presets supported by the Kuka Allegro tasks."""
-
-    isaacsim_physx = lift.PhysicsCfg().isaacsim_physx
-    ovphysx = OvPhysxCfg(
-        gpu_max_rigid_patch_count=4 * 5 * 2**15,
-        gpu_found_lost_pairs_capacity=2**26,
-    )
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx, ovphysx=ovphysx)
-    newton_mjwarp = lift.PhysicsCfg().newton_mjwarp
-    default = newton_mjwarp
-
-
 @configclass
 class KukaAllegroSceneCfg(lift.SceneCfg):
     """KukaAllegro scene for the Lift and Reorient tasks.
@@ -105,7 +88,6 @@ class KukaAllegroMixinCfg:
 
     def __post_init__(self: lift.ReorientEnvCfg):
         super().__post_init__()
-        self.sim.physics = KukaAllegroPhysicsCfg()
         self.commands.object_pose.body_name = "palm_link"
         events = self.events.conditional_reset.params["terms"]
         events["reset_robot_wrist_joint"].params["asset_cfg"] = SceneEntityCfg("robot", joint_names="iiwa7_joint_7")

source/isaaclab_tasks/isaaclab_tasks/core/lift/lift_env_cfg.py

@@ -6,6 +6,7 @@
 from dataclasses import MISSING
 
 from isaaclab_newton.physics import MJWarpSolverCfg, NewtonCfg, NewtonCollisionPipelineCfg, NewtonShapeCfg
+from isaaclab_ov.physics import OvPhysxCfg
 from isaaclab_physx.physics import PhysxCfg
 
 import isaaclab.sim as sim_utils
@@ -490,6 +491,10 @@ class PhysicsCfg(PresetCfg):
         gpu_max_rigid_patch_count=4 * 5 * 2**15,
         gpu_found_lost_pairs_capacity=2**26,
     )
+    ovphysx = OvPhysxCfg(
+        gpu_max_rigid_patch_count=4 * 5 * 2**15,
+        gpu_found_lost_pairs_capacity=2**26,
+    )
     newton_mjwarp = NewtonCfg(
         solver_cfg=MJWarpSolverCfg(
             solver="newton",
@@ -509,7 +514,7 @@ class PhysicsCfg(PresetCfg):
         num_substeps=2,
         debug_mode=False,
     )
-    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx)
+    physx = PhysxAutoCfg(isaacsim_physx=isaacsim_physx, ovphysx=ovphysx)
     default = newton_mjwarp