[NeoZng]

Description

The ANYmal symmetry augmentation used by the rsl_rl_with_symmetry agents hard-coded joint indices for the PhysX joint order. The velocity tasks default to Newton, where ANYmal's native order is depth-first, so every mirrored joint observation and action came from the wrong joint.

This PR resolves the left-right and front-back permutations and signs from the robot's joint_names, using the ANYmal <L|R><F|H>_<HAA|HFE|KFE> naming, and feeds them into the cached permutation tables from #8105 (now keyed by joint order). The sign conventions are unchanged: HAA is negated for left-right, and HFE/KFE for front-back. With the PhysX order the tables equal the previous ones.

Resolving by name matches the ordering contract, where public order is backend-native unless joint_ordering is set, and works for any joint_ordering; ANYmal-B/C use the same joint names. Pinning joint_ordering="physx" in the task would add a per-step reorder on Newton and change the observation and action layout of existing Newton checkpoints.

Fixes #8204

Verification on Isaac-Velocity-Flat-AnymalD and Isaac-Velocity-Rough-AnymalD, on both PhysX and Newton, at the current head:

• Wrong mirrored joints go from 12/12 to 0/12 on Newton, and stay at 0/12 on PhysX.
• The physical mirror check (base-frame feet of the mirrored configuration against the mirrored feet) goes from 0.17-0.42 m to below 1e-5 m on Newton.
• test_anymal_symmetry.py keeps the PhysX reference check from [Camera] Remove remaining hot-path host syncs and overhead [7B/7] #8105 and adds one check that the Newton order is mirrored like the PhysX order with the joint columns reordered; it fails on develop and passes with this change.
• The per-call path is unchanged: one cached gather and multiply per transform.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Release backport

• Backport this pull request to the active release branch after it merges into develop

Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with uv run isaaclab --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have validated the changed behavior with focused coverage and applied the test-audit criteria to any test changes
• I have added a changelog fragment under source/<pkg>/changelog.d/ for every touched package (do not edit CHANGELOG.rst or bump package versions — CI handles that)
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[greptile-apps]

Confidence Score: 4/5

[Medium risk] Fixes ANYmal robot symmetry augmentation for different physics backends.

The PR should not merge until the documented no-input call is preserved.

Findings

1.  Default call now raises ▶

Summary

The PR replaces fixed PhysX joint indices in ANYmal symmetry augmentation with joint-name-derived permutations and adds coverage for PhysX and Newton orders.

• The name-based mapping aligns with the configured joint observation and action order.
• The new device-selection step breaks calls made with both optional inputs omitted.

_{Reviews (1) · Last reviewed commit: "Resolve ANYmal symmetry joint mirrors by..."}

[isaaclab-review-bot]

Isaac Lab Review Bot

The name-derived symmetry maps correctly replace backend-specific joint indices and preserve the existing mirror composition, but the change breaks the valid no-input call path and introduces two style inconsistencies that should be cleaned up.

• Design and architecture: Resolving permutations from the articulation’s joint names correctly assigns ordering ownership to the asset rather than duplicating a PhysX-specific index table. The diagonal transformation still composes front-back over left-right. The two direction-specific action helpers no longer own distinct behavior, however, and should be replaced by direct _switch_joints calls.
• API: compute_symmetric_states retains its signature and 4x augmentation layout, while its private transform helpers consistently receive the resolved maps. Its public optional-argument contract is not fully preserved because calling it with both obs and actions omitted now fails instead of returning (None, None).
• Compatibility and deprecation: Breaking changes: compute_symmetric_states(env) previously returned (None, None), consistent with both inputs being optional, but now dereferences actions.device when both inputs are omitted and raises AttributeError. No guard or deprecation bridge accompanies this regression; return early or defer map resolution into the consuming branches.
• Implementation: The gather-and-multiply implementation returns fresh tensors, preserves the left-right and front-back sign conventions, and uses an immutable (joint_names, device) cache key with a clear lifetime. Add handling for the both-inputs-omitted path before selecting a device. The now-identical action forwarding helpers should be removed in favor of direct _switch_joints calls.
• Style consistency: Two concrete contribution-guide inconsistencies remain: _transform_actions_left_right and _transform_actions_front_back are identical one-line wrappers around _switch_joints, contrary to the guidance against trivial forwarding helpers, and _ANYMAL_JOINT_NAME is defined after functions instead of in the constants section following imports.
• Test quality: The new parametrized test provides focused regression coverage for both PhysX and Newton joint orders, checks observations and actions at the owning symmetry boundary, and derives expected results from independent mirror tables. It is not duplicated by the supplied existing tests. It does not cover the regressed call where both optional inputs are omitted.

Minor fixes needed. Posted 3 actionable findings inline.

Automated review; human maintainers own approval decisions.

[NeoZng]

Merged develop. #8105 turned these helpers into cached permutation tables that still assumed the PhysX joint order; the tables are now built from the robot's joint names, and the #8105 reference test runs unchanged on the PhysX order.

[NeoZng]

Correction to my earlier replies: after merging develop, #8105's cached tables replaced the _switch_joints change, so the action wrappers are #8105's with a joint_names argument. bbd9ed9 also shortens the name lookup and replaces the mirror tables in the test with one check against the PhysX order.

[AntoineRichard]

LGTM! Thanks for the fix @NeoZng

[kellyguo11]

run-ci

[kellyguo11]

run-ci

[isaaclab-bot]

Backported to release/3.0.0 as b9efdb7.