Enable lightwheel kitchen mesh placement

[qianl-nv]

Summary

Mesh kitchen placement; bind pool on env runtime

Detailed description

• Lightwheel kitchen bench uses mesh collision mode through PlaceableAsset kwargs; set it to mesh for the droid pick and place yaml; keep the default as bbox for other existing environments.
• Pass the live placement pool through env_kwargs instead of EventTermCfg params so mesh placement Warp caches do not hit configclass deepcopy/pickle ("ctypes objects containing pointers cannot be pickled")
• Reset placement_reset event uses empty params and reads the pool from IsaacLabArenaManagerBasedRLEnv.placement_pool

Note: With Fabric enabled, Warp caches on the pool can hide the Droid stand_instanceable in Kit viz while physics stays correct; use --disable_fabric for viewport runs (4 env / 2000-step benchmark: 87.0 vs 86.5 ms/step rollout, no meaningful difference)

• With background bbox mode (collision with backgroudn object)

• With background mesh mode + fix + fabric (stand visual disappear)

• With background mesh mode + fix + disable fabric

[greptile-apps]

Placement pool lost in callback

When a relation-based environment with reset-time placement is launched through the IsaacLab external callback, the callback discards the env_kwargs containing placement_pool. The environment is then constructed with a null pool, causing its initial placement reset to fail with AssertionError: Env has no placement pool; build through ArenaEnvBuilder.

Knowledge Base Used: Environment builder flow

[greptile-apps]

Greptile Summary

This PR enables mesh-based Lightwheel kitchen collision placement and moves the reset placement pool out of event configuration.

• Adds configurable collision mode and non-watertight mesh handling to placeable assets and the Lightwheel kitchen background.
• Returns the live placement pool from relation solving and passes it to the runtime environment.
• Makes reset placement retrieve assets and layouts from the environment-bound pool.
• Updates placement and background-collision tests for the new runtime ownership model.

Confidence Score: 4/5

The external IsaacLab callback path must preserve the live placement pool before this PR is safe to merge.

Reset-time relation placement now depends on an environment constructor keyword that the direct builder path forwards, but the supported external callback discards before IsaacLab constructs and initially resets the environment.

Files Needing Attention: isaaclab_arena/environments/arena_env_builder.py and isaaclab_arena/environments/isaaclab_interop.py

Important Files Changed

Filename	Overview
isaaclab_arena/environments/arena_env_builder.py	Returns the live placement pool through environment kwargs, but that transport does not survive the external-callback registration flow.
isaaclab_arena/environments/relation_solver_interface.py	Separates the reset event configuration from the live placement pool and returns both to the builder.
isaaclab_arena/environments/isaaclab_arena_manager_based_env.py	Stores an optionally supplied placement pool before base-environment initialization and exposes it through a property.
isaaclab_arena/relations/placement_events.py	Retrieves reset state from the runtime environment and fails fast when the pool was not forwarded.
isaaclab_arena/relations/placement_asset.py	Accepts per-asset collision mode and mesh-repair settings while retaining existing defaults.
isaaclab_arena/assets/background_library.py	Forwards Lightwheel kitchen parameters through the asset constructor hierarchy.
isaaclab_arena_environments/kitchen_bench/droid_pick_and_place_lightwheel_kitchen.yaml	Enables unrepaired mesh collision for the Lightwheel kitchen background.

Sequence Diagram

sequenceDiagram
  participant Builder as ArenaEnvBuilder
  participant Callback as IsaacLab external callback
  participant Gym as gym.make
  participant Env as Arena runtime env
  participant Reset as placement_reset
  Builder->>Builder: Solve relations and create pool
  Builder->>Callback: build_registered() returns cfg + env_kwargs
  Callback--xGym: placement_pool kwargs discarded
  Gym->>Env: "Construct with placement_pool=None"
  Env->>Reset: Initial reset
  Reset-->>Env: Assertion: placement pool missing

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_{Reviews (1): Last reviewed commit: "Bind placement pool on env at runtime" | Re-trigger Greptile}

[arena-review-bot]

🤖 Isaac Lab-Arena Review Bot

Summary

Enables mesh-mode collision placement for the Lightwheel kitchen background and moves the live PooledObjectPlacer off EventTermCfg.params onto the env at runtime (via env_kwargs), so mesh-mode Warp caches no longer trip configclass deepcopy/pickle. The refactor is clean and mirrors the existing variation_recorder plumbing: the reset event now reads the pool from env.unwrapped.placement_pool and derives its assets from pool.objects (the same list previously passed as params).

Findings

No blocking issues. The collision_mode: mesh YAML string threads correctly through **kwargs to PlaceableAsset, where CollisionMode("mesh") normalizes it; storing the pool on the runtime env is the right layer; and get_placement_pool's getattr(..., "placement_pool", None) reads a declared property with a graceful None for non-pooled envs (a contract callers like placement_pool_validation already rely on), so it is not the ad-hoc-storage smell.

Test Coverage

Good. Existing non-sim unit tests are updated to the new signatures, and two new regression tests cover the exact deepcopy/_validate path that previously failed under mesh mode — test_dynamic_spawn_pose_event_cfg_deepcopy_after_mesh_solve and test_solve_and_apply_relation_placement_drops_embodiment_from_runtime_pool. These stay sim-free (MagicMock envs), so the inner/outer pattern is not needed.

Verdict

Ship it.

[qianl-nv]

Won't go with this approach. willl use #972 instead.