refactor: split motion tracking common modules

[caozx1110]

Summary

• Extract shared motion-tracking owner modules for config, reset planning, domain randomization, rewards, observations, terminations, transforms, motion loading, and numba acceleration.
• Route G1 tracking/flip/box profiles and X2 flip tracking through the common engine while keeping task-owned profile classes and Hydra task owner YAML behavior.
• Add focused reward/config/loader/numba tests for the extracted common modules and preserve numpy/numba parity coverage.

Impact

• Keeps backend-specific behavior behind backend/config owner boundaries; task selection remains via task=<task>/<backend>.
• Reduces g1/tracking.py to a thin compatibility/profile entrypoint and moves hot-path reward/observation math into testable common modules.
• Reward hooks now consume RewardContext, matching the extracted common reward dispatch.

Validation

• NUMBA_THREADING_LAYER=workqueue make test-all — 1559 passed, 32 skipped, 266 deselected, 1 xfailed.

Fixes #135

[Copilot]

Pull request overview

Refactors the motion-tracking environments by extracting the shared (robot-agnostic) tracking engine into unilab.envs.motion_tracking.common, keeping per-robot/profile modules (G1/X2) as thin registry/profile layers while preserving Hydra task owner behavior and numpy/numba parity coverage.

Changes:

• Introduces a shared motion-tracking engine (common/tracking.py) plus owner modules for config, reset planning, transforms, terminations, rewards, domain randomization, motion loading/sampling, and the numba accelerator.
• Updates G1/X2 motion-tracking env/profile modules to route through the shared engine while retaining legacy symbol imports/aliases where needed.
• Adds/updates focused tests to lock reward math/dispatch and ensure numba parity still holds after the extraction.

Reviewed changes

Copilot reviewed 21 out of 22 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/envs/test_motion_tracking_rewards.py	New guard tests for extracted common reward terms and reward reduction logic.
tests/envs/test_motion_loader.py	Updates tests to import the extracted common motion loader/sampler.
tests/envs/test_g1_motion_tracking_numba.py	Switches numba accelerator imports to the extracted common implementation.
tests/envs/test_env_configs.py	Adjusts imports and expectations for common motion loader/tracking/DR provider names.
src/unilab/envs/motion_tracking/x2/flip_tracking.py	Migrates X2 flip tracking to the common config + deploy engine.
src/unilab/envs/motion_tracking/g1/tracking.py	Reduces G1 tracking module to registry/profile wrappers + backward-compatible re-exports.
src/unilab/envs/motion_tracking/g1/tracking_obs.py	Migrates custom reward terms to the new RewardContext call signature.
src/unilab/envs/motion_tracking/g1/motion_box_loader.py	Routes box motion loader dependencies through the extracted common loader types.
src/unilab/envs/motion_tracking/g1/flip_tracking.py	Removes duplicated zero-randomization helpers in favor of common equivalents.
src/unilab/envs/motion_tracking/g1/box_tracking.py	Updates object reward terms to accept RewardContext consistently with common reward dispatch.
src/unilab/envs/motion_tracking/common/init.py	Introduces the common motion-tracking package namespace.
src/unilab/envs/motion_tracking/common/config.py	Adds shared dataclass config types + backward-compatible aliases and helpers.
src/unilab/envs/motion_tracking/common/motion_loader.py	Extracts shared motion loading/sampling logic (including multi-clip support).
src/unilab/envs/motion_tracking/common/reset.py	Extracts reset reference-state construction.
src/unilab/envs/motion_tracking/common/transforms.py	Extracts yaw-aligned relative transform updates used by obs/reward/termination.
src/unilab/envs/motion_tracking/common/observations.py	Extracts shared observation building and anchor-frame transform writers.
src/unilab/envs/motion_tracking/common/terminations.py	Extracts shared termination computation.
src/unilab/envs/motion_tracking/common/rewards.py	Extracts shared reward config, context, term functions, and reducer.
src/unilab/envs/motion_tracking/common/domain_randomization.py	Extracts the DR reset/observation provider into common owner space.
src/unilab/envs/motion_tracking/common/tracking.py	New shared env engine orchestrating step/reset, delegating math to owner modules.
src/unilab/envs/motion_tracking/common/numba.py	Renames accelerator to common MotionTrackingNumbaAccelerator and updates messaging.
benchmark/benchmark_g1_motion_tracking_numba.py	Updates benchmarking harness to use the extracted common numba accelerator.

Comments suppressed due to low confidence (1)

src/unilab/envs/motion_tracking/common/numba.py:916

• MotionTrackingNumbaAccelerator was renamed to be robot-agnostic, but the result dataclasses returned by compute() / compute_update_state() are still named G1MotionTrackingNumbaResult / G1MotionTrackingNumbaUpdateStateResult. This is inconsistent for a common module and makes the public surface confusing for non-G1 trackers (e.g. X2). Consider adding MotionTracking-prefixed aliases (or renaming with backward-compatible aliases).

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