[Backport release/3.0.0] Bring over the remaining cloner change (#8045)

[StafaH]

Description

Backport #8045 to release/3.0.0, including its cloner implementation, tests, documentation, and package changelog fragments. The release branch otherwise contains the merged develop PRs from the recent catch-up window. #8059 is already covered by merged backport #8069 and is not included here.

The source cherry-pick applies cleanly except for docs/source/how-to/cloning.rst. The resolution keeps the release branch's valid replicate_physics=False guidance alongside the new cloner API guide. This PR provides a release-based alternative to the bot's draft #8072, with the later #8071 and #8069 release commits included in its base.

Direct ClonePlan callers and custom clone contexts must follow the migration guidance included with #8045. Normal InteractiveScene and clone_plan_from_env_0 signatures remain unchanged.

Validation

• 44 core cloner tests passed.
• 11 Newton cloner tests and 4 subtests passed.
• uv run isaaclab -f passed with the changelog base set to release/3.0.0.
• git diff --check passed.
• Full documentation build passed with the dev extra (Sphinx 8.2.3, warnings treated as errors).

Type of change

• Breaking change to direct cloner APIs, with migration documentation.
• Release backport.

Checklist

• Read the contribution guidelines.
• Ran formatting and lint checks.
• Included documentation, tests, and changelog fragments from the source PR.
• Original contributor already listed.

This PR targets the release branch; no additional backport is needed.

[greptile-apps]

Confidence Score: 3/5

[High risk] Refactors the core cloning topology and API across the simulation framework.

The PR should not merge until OVRTX handles plans without positions and deformable discovery excludes unused prototypes.

Findings

1.  Optional positions break OVRTX ▶
2.  Unused deformables enter visualization ▶

Summary

The backport replaces clone-plan source/mask rows with reusable asset and world-prototype topology, and migrates scene construction, backend replication, consumers, tests, and documentation.

• Optional placement is not handled by OVRTX cloning.
• Deformable discovery does not exclude unused world prototypes.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    C[Asset configurations] --> P[Clone plan and world topology]
    P --> S[InteractiveScene authoring]
    S --> B[USD and native clone backends]
    P --> D[Deformable discovery]
    B --> R[Physics and rendering]
    D --> R

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_{Reviews (1) · Last reviewed commit: "[Cloner] Represent worlds with reusable ..."}

[greptile-apps]

Optional positions break OVRTX

If a clone plan is created without positions, as make_clone_plan permits, this assignment puts None into a numeric transform array. OVRTX scene initialization then fails instead of preserving the authored environment placement.

Knowledge Base Used: Physics backend extensions

[greptile-apps]

Unused deformables enter visualization

When a world prototype is defined but no destination world selects it, these lines still discover its deformable source. Expansion has no destination for that source and retains it as a shared entry, so OVPhysX or Newton visualization can import geometry that the plan places in no world.

Knowledge Base Used:

• Scene and asset composition
• Physics backend extensions

[isaaclab-review-bot]

Isaac Lab Review Bot

The backport consistently migrates cloner consumers to PrototypeWorldTopology, but the OVRTX renderer does not honor the new optional ClonePlan.positions contract.

• Design and architecture: The topology and host-side naming/placement split is propagated across USD, PhysX, OVPhysX, Newton, OVRTX, sensors, and scene-data consumers. The remaining inconsistency is that OVRTX still assumes every plan contains explicit positions.
• API: ClonePlan.positions is documented as optional, where None preserves authored placement. OVRTX no longer validates this narrower requirement and therefore exposes an accidental failure instead of supporting the contract or reporting a clear precondition.
• Implementation: In OVRTXRenderer._clone_sources, assigning plan.positions directly into the translation slice fails when positions is None. Skip the environment-transform write in that case, or restore explicit validation with a clear error before cloning.

Minor fixes needed. Posted 1 actionable finding inline.

Automated review; human maintainers own approval decisions.

[isaaclab-review-bot]

🟡 Warning · Api — OVRTX cannot accept plans without positions

ClonePlan.positions is documented here as optional, with None preserving authored placement, and UsdReplicateContext.replicate guards on it. prepare_stage no longer rejects such plans, so xforms[:, 3, :3] = plan.positions raises an unrelated TypeError instead of the previous explicit error. Either skip the environment-transform write when positions is None, matching the USD context, or restore an explicit validation message.

[StafaH]

run-ci