Fold deformable migration page into the 3.0 migration guide

[mmichelis]

Description

docs/source/migration/migrating_deformables.rst was a 252-line child page hanging off the 3.0 migration guide, which already carried a ~20-line "Deformable Object API Changes" summary whose only job was to link out to it. The deformable body API change is a one-time 2.x to 3.0 concern, so it does not warrant a dedicated page, and most of the page's content was duplicated from sources that are already maintained elsewhere:

• The "Added Properties" and "Material Changes" property lists restate docstrings that autodoc already renders from schemas_cfg.py and physics_materials_cfg.py. The added-property list had in fact already drifted from source, omitting settling_threshold, sleep_threshold, max_depenetration_velocity, self_collision and self_collision_filter_distance.
• The surface-deformable and USD-file code examples repeat scripts/demos/deformables.py verbatim, and the volume example repeats the deformable object tutorial.
• The root_physx_view to root_view section repeats the migration guide's own asset-view section.

This PR folds the content that cannot be recovered from source into the existing "Deformable Object API Changes" section and deletes the child page. Net change is 252 lines removed against 81 added.

What was kept:

• The surface versus volume distinction and which material cfg selects which type, since this is stated nowhere else as clearly.
• A trimmed import table, now using the short isaaclab_newton.sim paths so the Newton rows are consistent with the PhysX rows. Both packages use the same lazy_export machinery, so the deeper submodule paths the old page used were unnecessary.
• The removed-properties table with replacements, now class-qualified because the entries span PhysxDeformableBodyPropertiesCfg, PhysxDeformableBodyMaterialCfg and the deleted PhysxDeformableCollisionPropertiesCfg. Autodoc can never render a class that no longer exists, so a migration note is the only place this can live.
• The volume-only kinematic target restriction. This is enforced at runtime in deformable_object.py but has no Raises: entry in the method docstring, so the migration guide is currently the only documentation of it.

Code examples were replaced with pointers to the deformable object tutorial and scripts/demos/deformables.py, both of which are runnable and cover the volume, surface and USD-asset cases.

Type of change

• Documentation update

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 ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added a changelog fragment under source/<pkg>/changelog.d/ for every touched package (do not edit CHANGELOG.rst or bump extension.toml — CI handles that)
• I have added my name to the CONTRIBUTORS.md or my name already exists there

Notes on the two unchecked items: this is a docs-only change with no source package touched, so there is nothing to test and no package needs a changelog fragment.

Verification: a full Sphinx build succeeds with 15 warnings, the same count as before the change, and all 15 are pre-existing duplicate object description autodoc warnings unrelated to this PR. ./isaaclab.sh --format passes, including the RST hooks and the changelog fragment check. No references to the deleted page remain anywhere in the repository.

[greptile-apps]

Greptile Summary

The PR removes the standalone deformables migration page and folds its durable guidance into the Isaac Lab 3.0 migration guide.

• Adds concise volume-versus-surface deformable guidance, backend import mappings, removed-property replacements, and behavior changes.
• Replaces duplicated examples and property listings with references to maintained tutorials, demos, and API documentation.
• Removes the obsolete child page from the migration toctree.

Confidence Score: 4/5

The documentation consolidation should not merge until the associated migration agent skill is updated to cover the newly incorporated deformable guidance.

The guide explicitly requires same-change synchronization with its agent skill, but the skill still omits deformables and can therefore provide incomplete migration guidance for affected projects.

Files Needing Attention: docs/source/migration/migrating_to_isaaclab_3-0.rst and skills/user/migrate-2x-to-3x/SKILL.md

Important Files Changed

Filename	Overview
docs/source/migration/migrating_to_isaaclab_3-0.rst	Consolidates deformable migration guidance correctly, but does not apply the page's required corresponding update to the migration agent skill.
docs/source/migration/migrating_deformables.rst	Deletes the redundant child page after moving its essential migration guidance into the main 3.0 guide.

Comments Outside Diff (1)

1. docs/source/migration/migrating_to_isaaclab_3-0.rst, line 12 (link)

   Deformable skill guidance stays stale

   When the migration skill handles a project using the former deformable APIs, its migration-area workflow omits the new deformable guidance added here, causing it to miss backend import replacements and removed configuration fields. This page explicitly requires the source-of-truth guide and skill to be updated together, so please synchronize skills/user/migrate-2x-to-3x/SKILL.md and its supporting checks in this change.

   Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

_{Reviews (1): Last reviewed commit: "Fold deformable migration page into the ..." | Re-trigger Greptile}

[isaaclab-review-bot]

Isaac Lab Review Bot

This documentation-only change consolidates the deformable 2.x-to-3.0 migration guidance into the main 3.0 guide and removes the former child page and its toctree entry. No candidate findings were supplied or supported for acceptance.

• Design and architecture: Keeping this one-time migration material in the existing "Deformable Object API Changes" section is coherent and reduces duplicated documentation. The child page and its toctree integration are removed together; the known tradeoff is that the former published page URL has no redirect mechanism and will return 404.
• API: No source API is changed. The consolidated guide retains the backend-specific import paths, removed-property replacements, view-property deprecation, and surface-versus-volume behavior distinctions. The shortened Newton class references are the relevant documentation-resolution surface, and the reported successful Sphinx build indicates they resolve without introducing warnings.
• Implementation: The changed documentation preserves the principal migration paths for deformable properties, materials, collision offsets, kinematic targets, and root views while replacing duplicated examples with maintained tutorial and demo references. The patch also removes the obsolete toctree entry, avoiding a dangling document inclusion.

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.