Fix OVD Recorder hanging silently on non-PhysX backends

[matthewtrepte]

Description

The OVD Recorder (AnimationRecorder) only works with the PhysX backend, but most tasks now default to Newton. As a result, --anim_recording_enabled silently did nothing: recording never started, --anim_recording_stop_time was never reached, and the process ran until manually killed with nothing saved.

This PR:

• Raises a clear error at simulation startup when --anim_recording_enabled is set on a physics backend that doesn't support the OVD Recorder (via a new PhysicsManager.supports_anim_recording flag, set True only on PhysxManager), naming the active backend and pointing the user to physics=isaacsim_physx.
• Adds an overrides parameter to parse_env_cfg() so standalone (non-Hydra) scripts can apply physics=/renderer=/presets= overrides, and updates the run_cartpole_rl_env.py tutorial to forward unrecognized CLI args this way.
• Updates docs/source/how-to/record_animation.rst to note the PhysX requirement and fix the example command so it actually works as documented.

Type of change

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

Testing

• Reran the exact documented repro command on the default (Newton) backend: now fails fast with a clear ValueError instead of hanging.
• Reran with physics=isaacsim_physx: recording stops at --anim_recording_stop_time, saves baked_animation_recording.usda, process exits cleanly (exit code 0).
• uv run isaaclab -f passes for all touched files.
• Targeted tests (test_physics_manager_lifecycle.py, test_hydra.py): 94 passed.
• Docs build (make -C docs current-docs, warnings-as-errors): succeeded with no warnings.

Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with uv run isaaclab -f
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added a changelog fragment under source/<pkg>/changelog.d/ for every touched package
• I have added my name to CONTRIBUTORS.md (already present)

Release backport

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

[greptile-apps]

Greptile Summary

The PR makes animation recording fail fast on unsupported physics backends and enables standalone task configuration overrides for the Cartpole tutorial.

• Adds a backend capability flag, enabled only by PhysX, and validates animation-recording support during simulation startup.
• Adds override forwarding through parse_env_cfg and the standalone Cartpole tutorial.
• Updates animation-recording documentation and package changelogs.

Confidence Score: 4/5

The PR appears safe to merge, with a non-blocking API validation issue for callers that provide one override as a bare string.

The backend guard and tutorial forwarding are coherent, but the new public overrides parameter permits a string value that downstream composition parses character by character.

Files Needing Attention: source/isaaclab_tasks/isaaclab_tasks/utils/parse_cfg.py

Important Files Changed

Filename	Overview
source/isaaclab/isaaclab/physics/physics_manager.py	Adds a startup capability check that rejects OVD animation recording on unsupported physics backends.
source/isaaclab_physx/isaaclab_physx/physics/physx_manager.py	Declares PhysX support for OVD animation recording.
source/isaaclab_tasks/isaaclab_tasks/utils/parse_cfg.py	Adds standalone override composition, but a bare string is accepted by the declared type and then misinterpreted as individual overrides.
scripts/tutorials/03_envs/run_cartpole_rl_env.py	Forwards unknown command-line tokens to task configuration composition so backend selectors work.
docs/source/how-to/record_animation.rst	Documents the PhysX requirement and updates the recording commands accordingly.

_{Reviews (1): Last reviewed commit: "Fix OVD Recorder hanging silently on non..." | Re-trigger Greptile}

[greptile-apps]

Bare strings split into characters

The new Sequence[str] API also accepts a bare string, so overrides="physics=isaacsim_physx" is forwarded and processed character by character, producing an unrelated configuration parsing error instead of selecting PhysX. Validate or normalize this input so one override cannot be mistaken for a sequence of overrides.

[isaaclab-review-bot]

Isaac Lab Review Bot

The capability-gated startup check directly addresses silent OVD recording failures on non-PhysX backends, while the new configuration override path makes the documented PhysX selection work from the cartpole tutorial. The TODO text accurately discloses the current standalone-script limitation and does not establish a material documentation defect requiring pre-merge action.

• Design and architecture: The opt-in supports_anim_recording ClassVar centralizes backend capability detection in PhysicsManager.initialize(), with only PhysxManager enabling recording. This preserves safe defaults for other backends and fails before unsupported recording can hang.
• API: parse_env_cfg() adds overrides as a trailing parameter with an empty default, preserving existing callers and prior configuration behavior. The override is passed through the existing resolve_task_config boundary, and the capability flag is additive. Documentation and package changelog coverage accompany the user-visible changes.
• Implementation: The non-PhysX failure path, PhysX opt-in, override composition, and cartpole CLI forwarding are internally consistent. Using parse_known_args() means unknown or mistyped options now reach Hydra resolution rather than failing directly in argparse, but they should still surface as configuration errors; this is a non-blocking diagnostic tradeoff.

No blocking issues. No inline issue met the actionable-evidence threshold; the assessment above records the review feedback.

Automated review; human maintainers own approval decisions.

[matthewtrepte]

run-ci

[kellyguo11]

do we also need --extra isaacsim in the command?

[matthewtrepte]

Checked — I don't think we need it here, and would rather stay consistent with the sibling tutorial docs (run_articulation.rst, launch_app.rst, record_video.rst, etc.), all of which also omit --extra isaacsim in their example commands. That extra is shown in the installation guide's first-run verification command (uv run --extra isaacsim isaaclab train ...), which is what actually syncs it into the environment; once that's done, plain uv run python ... reuses the already-resolved env without needing to repeat the extra. I've also run this exact command many times against this repo without --extra isaacsim and it works fine. Let me know if you'd rather I add it for explicitness anyway — happy to if that's the preference, just flagging the existing convention first.

[matthewtrepte]

Correction to my earlier reply — I was wrong. isaacsim is genuinely an optional extra (pyproject.toml's [project.optional-dependencies], not a base dependency), so a fresh uv sync without it won't have Isaac Sim at all, and physics=isaacsim_physx needs it.

Your #7054 (merged yesterday) already established the right convention for exactly this in the new docs/source/concepts/visualization.rst:

"Most tasks default to a PhysX backend, which requires Isaac Sim. If it isn't installed yet, add --extra isaacsim to the uv run commands above; see installation-optional-extras for details."

I've added the same note here rather than baking --extra isaacsim into the example command itself, matching that doc's pattern.

[kellyguo11]

run-ci

[isaaclab-bot]

Backported to release/3.0.0 as b6afa8e.