[Backport release/3.0.0] Bundle #7272, #7121, #7183, #7306, #7305, and #7303

[ooctipus]

Description

Backports six merged PRs to release/3.0.0 as separate provenance-preserving cherry-picks:

Source PR	Source commit	Backport commit	Scope
#7272	0081477fea2	c9fc1997476	Fix scene-wide gravity distributions for PhysX and OvPhysX.
#7121	9f65e3d4fd2	cce8acd84e1	Fix backend-factory fallback before simulator initialization.
#7183	3fcc9c6b824	99d58d3d3c4	Streamline the getting-started documentation.
#7306	6aad90be0ae	9a786cc028a	Optimize Newton test runtime.
#7305	1c9ba908cf1	a2dc8ce948e	Disable Warp autodiff in the test suite.
#7303	393fc37d2b0	249a5cb97d8	Remove post-Hydra preset resolution.

#7272 forwards the validated uniform, log_uniform, or gaussian distribution through both scene-wide backend paths. Newton behavior is unchanged.

#7121 makes factory resolution fall back to Newton when no SimulationContext exists while retaining the visualizer contract of reporting no active backend before context creation.

#7183 is documentation-only. #7306 and #7305 change test infrastructure only; they do not change runtime behavior.

#7303 makes resolve_task_config and parse_env_cfg the task-composition boundary. Runtime consumers now require concrete physics, renderer, and camera configurations and no longer attempt late preset fallback after Hydra composition.

The branch was synchronized with the current release/3.0.0 tip containing #7301 before #7303 was applied. All six source cherry-picks applied without conflicts. A file-by-file existence, mode, and blob audit confirmed that every #7303 path matches its merged source commit exactly.

Validation

#7272

• Regression verification against the unpatched release/3.0.0 tip — both PhysX and OvPhysX cases failed as expected.
• uv run --extra test --frozen python -m pytest -q source/isaaclab/test/envs/test_gravity_randomization.py source/isaaclab/test/envs/test_mdp_event_selectors.py — 7 passed.
• uv run --extra test --extra ovphysx --frozen python -m pytest -q source/isaaclab_ov/test/physics/test_ovphysx_gravity.py — 1 passed.

#7121

• Regression verification before the Fix backend factory fallback before simulator initialization #7121 cherry-pick reproduced the original NoneType.physics_manager failure.
• uv run --extra test --frozen python -m pytest -q source/isaaclab/test/utils/test_backend_utils.py source/isaaclab/test/visualizers/test_visualizer.py — 18 passed.

#7183

• uv run --frozen --extra test python -m pytest --noconftest -q tools/test/test_environ_docs.py — 26 passed.

#7306

• All 9 affected paths match the merged source PR exactly.
• The full simulator-backed Newton suite is left to backport CI because this local worktree does not include the full Isaac Sim runtime.

#7305

• Loaded the root conftest.py successfully with Warp unavailable.
• Loaded it with Warp installed and confirmed wp.config.enable_backward is False.

#7303

• Hydra and Shadow Hand camera suites — 129 passed.
• Benchmark capture and RL entrypoint suites — 31 passed.
• Experimental frontend and custom-coupling suites — 74 passed, 1 skipped.
• Ruff and Ruff-format passed for every changed Python path.
• Source/backport audit — 54 paths checked, 0 mismatches.
• The Isaac Sim-backed integration case is left to CI because this local worktree is kitless.

Repository gates

• git diff --check upstream/release/3.0.0...HEAD — passed.

[isaaclab-review-bot]

Isaac Lab Review Bot

The patch correctly caches the validated gravity distribution and forwards it through the PhysX and OvPhysX scene-wide randomization paths instead of forcing uniform sampling. The focused regression test and changelog fragment cover the user-visible fix.

• Design and architecture: Backend dispatch and ownership remain unchanged. The cached distribution is used only by the two scene-wide backend paths, while Newton continues using its existing per-environment sampling implementation.
• API: The public call signature, defaults, parameter names, and gravity unit documentation are unchanged. The existing contract that distribution selection is cached during initialization is preserved, and the required source-package changelog fragment is present.
• Implementation: The distribution is validated before either backend can use it, and both changed calls pass the cached value to the existing randomization helper. Tensor placement, shapes, backend conversions, and gravity sinks remain unchanged. The parameterized regression test exercises both PhysX and OvPhysX dispatch with deterministic Gaussian sampling.

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.

[greptile-apps]

Greptile Summary

This backport makes scene-wide PhysX and OvPhysX gravity randomization honor the distribution validated during event initialization.

• Caches the configured gravity distribution for backend-specific calls.
• Forwards that distribution through both PhysX and OvPhysX sampling paths.
• Adds parameterized regression coverage for Gaussian sampling and documents the fix.

Confidence Score: 5/5

The PR appears safe to merge, with no actionable correctness, security, or quality issues identified.

The configured distribution is already validated during term initialization, the shared helper accepts each supported distribution, and both backend paths convert the sampled result into the expected three-value gravity representation.

Important Files Changed

Filename	Overview
source/isaaclab/isaaclab/envs/mdp/events.py	Correctly forwards the validated, initialization-time distribution to the shared randomization helper for both scene-wide backends.
source/isaaclab/test/envs/test_gravity_randomization.py	Exercises distinct PhysX and OvPhysX dispatch branches and verifies that Gaussian parameters reach each gravity sink.
source/isaaclab/changelog.d/antoiner-scene-gravity-distribution.rst	Accurately documents the corrected distribution behavior.

_{Reviews (1): Last reviewed commit: "Fix gravity distributions for PhysX and ..." | Re-trigger Greptile}