Adds strict type checking and clear split between cfg and implementation

[ooctipus]

Description

Adds strict type checking and split between cfg and implementaion

Fixes # (issue)

Type of change

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

Screenshots

Please attach before and after screenshots of the change if applicable.

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 updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[greptile-apps]

Greptile Summary

This PR separates configuration dataclasses from their implementation counterparts across the IsaacLab codebase, and defers heavy simulation-backend imports (omni, carb, pxr, isaacsim) so that config files can be loaded without a running Kit/simulator. Key changes include:

• Cfg/implementation split: Extracts *Cfg dataclasses into dedicated *_cfg.py files for controllers, devices, markers, visualization markers, env tasks (ant, cartpole, franka_cabinet, humanoid, quadcopter, shadow_hand, pre_trained_policy_action), and more.
• Deferred imports: Moves omni.kit.app, omni.physx, carb, pxr, isaacsim imports behind has_kit() guards or into local scope at point of use across env, manager, sensor, and MDP modules.
• has_kit() rework: Now checks sys.modules instead of attempting import omni.kit.app, avoiding forbidden side-effects during cfg-only loading.
• String-to-callable auto-resolution: _validate() in configclass.py now resolves "module.path:ClassName" strings into actual callables at validation time, enabling cfg files to reference implementation classes as strings instead of direct imports.
• New attach_cascading utility: Provides a reusable __getattr__/__dir__ pattern for cascading namespace packages.
• TYPE_CHECKING guards: MDP modules (observations, rewards, events, curriculums, terminations) now import asset/sensor types only under TYPE_CHECKING.

Issues found:

• The keyboard device cfg split is incomplete: Se2KeyboardCfg and Se3KeyboardCfg are duplicated (new *_cfg.py files created, but old definitions in se2_keyboard.py/se3_keyboard.py not removed, and keyboard/__init__.py not updated).
• Several task env cfg extractions are incomplete: CartpoleEnvCfg, CartpoleCamera*EnvCfg, and CartDoublePendulumEnvCfg were copied to new *_cfg.py files but the old definitions in the implementation files were not removed. The basic Isaac-Cartpole-Direct-v0 entry point still references the old module.
• sensor_base.py adds local imports without removing the existing top-level imports, creating redundancy.

Confidence Score: 3/5

• This PR is mostly safe but has incomplete migrations that result in duplicate class definitions across several files, which should be resolved before merging.
• The core architectural changes (deferred imports, has_kit() rework, TYPE_CHECKING guards) are well-implemented and safe. However, the cfg extraction was applied inconsistently: some environments (ant, franka_cabinet, humanoid, quadcopter, shadow_hand) were migrated completely, while others (cartpole, cart_double_pendulum, keyboard devices) have duplicate cfg class definitions across old and new files. The duplicate classes have subtly different type annotations (e.g., type[DeviceBase] vs type | str), which could cause confusion. No runtime breakage is expected from the duplicates since the old code paths still work, but the incomplete state suggests the PR needs cleanup before merge.
• Pay close attention to se2_keyboard_cfg.py, se3_keyboard_cfg.py (duplicate definitions not cleaned), cartpole/__init__.py (inconsistent entry point), cartpole_env_cfg.py, cartpole_camera_env_cfg.py, cart_double_pendulum_env_cfg.py (duplicate cfgs), and sensor_base.py (redundant imports).

Important Files Changed

Filename	Overview
source/isaaclab/isaaclab/utils/configclass.py	Adds string-to-callable auto-resolution in _validate(). Silent error suppression may mask typos. Side-effect in validation function is unusual.
source/isaaclab/isaaclab/utils/module.py	New utility for cascading namespace packages. Well-structured with caching via dict write-through. Clean implementation.
source/isaaclab/isaaclab/utils/version.py	has_kit() now avoids triggering imports via sys.modules check. Good improvement for cfg-only loading without Kit.
source/isaaclab/isaaclab/devices/keyboard/se2_keyboard_cfg.py	New cfg file but old definition NOT removed from se2_keyboard.py. Duplicate class with different class_type annotation. keyboard/init.py not updated.
source/isaaclab/isaaclab/devices/keyboard/se3_keyboard_cfg.py	Same issue as se2_keyboard_cfg.py - duplicate definition with se3_keyboard.py, init.py not updated.
source/isaaclab/isaaclab/envs/direct_rl_env.py	Guards omni.kit.app and omni.physx behind has_kit(). Import order slightly shuffled but functionally correct.
source/isaaclab/isaaclab/envs/mdp/events.py	Defers carb, omni.physics, pxr, isaacsim imports to point of use. Moves DeformableObject and TerrainImporter behind TYPE_CHECKING.
source/isaaclab/isaaclab/sensors/sensor_base.py	Adds local imports for omni.kit.app and isaaclab_physx but doesn't remove existing top-level imports, creating redundancy.
source/isaaclab_tasks/isaaclab_tasks/direct/ant/ant_env.py	Cfg class cleanly extracted to ant_env_cfg.py. Import chain properly updated.
source/isaaclab_tasks/isaaclab_tasks/direct/cartpole/init.py	Camera env entry points updated to _cfg module, but basic CartpoleEnvCfg still references cartpole_env (line 23). Inconsistent migration.
source/isaaclab_tasks/isaaclab_tasks/direct/cartpole/cartpole_env_cfg.py	New cfg file but CartpoleEnvCfg still duplicated in cartpole_env.py (not removed). Entry point not updated.
source/isaaclab_tasks/isaaclab_tasks/direct/cart_double_pendulum/cart_double_pendulum_env_cfg.py	New cfg file but CartDoublePendulumEnvCfg still duplicated in cart_double_pendulum_env.py (not removed).
source/isaaclab_tasks/isaaclab_tasks/direct/franka_cabinet/franka_cabinet_env.py	Cfg class cleanly extracted to franka_cabinet_env_cfg.py. Imports properly updated.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    subgraph "Before: Cfg + Impl coupled"
        A[env_cfg.py / env.py<br/>Combined file] -->|"import omni, carb, pxr"| B[Kit/Simulator Required]
        A -->|"contains Cfg + Env class"| C[Cannot load cfg<br/>without simulator]
    end

    subgraph "After: Cfg / Impl split"
        D[env_cfg.py<br/>Pure config dataclass] -->|"no simulator imports"| E[Loadable without Kit]
        F[env.py<br/>Implementation only] -->|"import omni, carb, pxr"| G[Kit required at runtime]
        F -->|"imports cfg from"| D
        H["configclass._validate()"] -->|"resolves 'mod:Class' strings"| I[string_to_callable]
        J["has_kit()"] -->|"sys.modules check"| K{"Kit running?"}
        K -->|"Yes"| L["import omni.kit.app"]
        K -->|"No"| M["Skip import"]
    end

    style C fill:#f99,stroke:#c00
    style E fill:#9f9,stroke:#0c0

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_{Last reviewed commit: 5f0641c}

[greptile-apps]

_{75 files reviewed, 5 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Silent suppression of resolution errors in validation

The contextlib.suppress(ImportError, AttributeError, ValueError) silently swallows errors when a string matching the "module.path:ClassName" pattern fails to resolve. If a user has a typo in a callable string (e.g., "isaaclab.controllers.rmp_flw:RmpFlowController"), it will be silently left as a string. The actual failure will then surface much later with a cryptic error when the string is used where a callable is expected.

Consider at minimum logging a warning when resolution fails, so users can debug configuration typos more easily:

if isinstance(value, str) and _CALLABLE_STR_RE.match(value):
    try:
        obj_dict[key] = string_to_callable(value)
    except (ImportError, AttributeError, ValueError):
        import logging
        logging.getLogger(__name__).debug(
            "Could not resolve callable string %r for field %r", value, key
        )

[kellyguo11]

looks like a good idea!

[greptile-apps]

Additional Comments (1)

source/isaaclab_tasks/isaaclab_tasks/direct/cartpole/__init__.py
Inconsistent entry point migration

The camera-based cartpole environments (lines 36, 47, 58, 69, 80, 91) were updated to point to cartpole_camera_env_cfg, but the basic Isaac-Cartpole-Direct-v0 entry point at this line still references cartpole_env:CartpoleEnvCfg. The CartpoleEnvCfg definition remains in cartpole_env.py and was also added to the new cartpole_env_cfg.py, creating a duplicate.

This should be updated to:

        "env_cfg_entry_point": f"{__name__}.cartpole_env_cfg:CartpoleEnvCfg",

And the CartpoleEnvCfg class should be removed from cartpole_env.py.

[kellyguo11]

looks like a good idea!