Download the plugin ZIP and SHA256SUMS.txt from the v0.1.8rc1 Pre-release. GitHub's automatic Source code archives are source snapshots. Follow the download, hash verification, extraction and SCA installation guide; SDK2.2.5 installs the extracted directory, not the ZIP. Source remains on main. Companion: USD v0.1.8rc2.
An independent SimpleCADAPI2.2.5 add-on for sourced physics in complete product packages. The Agent selects the applicable representation and material assumptions; deterministic code validates, calculates, saves and reopens them. New writes use metadataSchema1.7 and require truthful field, group or declaration sources. Submitted estimates take precedence over preset fillers; unknown descriptions never silently become wire.
Schema1.8 adds optional occurrence-bound revolute/prismatic motion limits, maximum velocity, joint friction, force drives (off/position/velocity), articulation declarations and a minimal sourced revolute-to-prismatic ideal mimic coupling. Native CAD frames and axes remain authoritative. Public update_config, update_package, and CLI update apply sourced partial changes without resetting other saved parameters or reusing an old value's provenance. Configurations with no new fields keep the existing1.7 behavior. See joint physics and units for SI units, damping composition, compatibility and backend limits.
The public circle_rod helper converts sourced circular-rod diameter, density, E and G into replayable lambda/EI/GJ wrappers. Derived records contain a supported rule, fixed formula and sourced input snapshots; serialized records are recalculated on validation. Decision records can bind task/material reasoning to actual saved fields. The reader retains contracts for schemas 1.0–1.6 without source relabeling or resegmentation; actual historical package coverage is limited to the identified 1.0 and 1.1 files below.
configure-cable supports two explicit categories and deterministic initial segmentation. Other supported round, planar slender bodies require a complete set-rigid-chain declaration and an Agent-chosen count. The model retains its inextensible, straight natural-state and per-joint damping limits; no online model service is required by the plugin. Candidate pairing: sca-physics==0.1.8rc1 with sca-usd-export==0.1.8rc2. The exporter makes its physics integration optional; geometry-only export does not require this add-on.
Historical0.1.6rc1/rc2 mechanics findings remain in the validation notes; software checks and saved formulas do not establish material calibration or universal physical accuracy. Current candidate evidence and migration limits are recorded in release preparation and the changelog.
Read Chinese usage, Agent decisions and sources, automatic cable workflow, installation and explicit chain contract. Source lives in this repository; installed payload/runtime/skill are separate copies. Generated assets and environments stay external.
The verified pair is sca-physics 0.1.8rc1 + sca-usd-export 0.1.8rc2, on Windows x86-64, CPython 3.12.15, SCA SDK 2.2.5, OpenUSD (usd-core) 26.8 and OCP (cadquery-ocp) 7.9.3.1. OpenUSD came from an isolated venv, not Isaac. This is an rc pre-release candidate, not a stable release or a guarantee for other combinations. The corresponding Release notes record the actual GitHub attachment download/install verification result.
Verified historical inputs are the 2026-10-19 physics 0.1.0/schema 1.0 pendulum package (SHA256 ba39ea3d58fbe8c59ca00153858fd72d6d00f091f71602374461ec6c7f4406ec) and the 2026-10-20 physics 0.1.3rc1/schema 1.1 mechanical package (54f37bbfd0576d88a2d7f7a718718fce0fa29cf8e3540601b3e1fcc29caf8893). Both passed native SDK loading, complete re-encoding/reloading, physics snapshot preservation and USD export/reopening. Exact input identities, producer evidence, old path/in-memory API calls and migration commands are in candidate compatibility.
旧无来源裸参数原样不兼容；按要求补充来源信息后，所测试案例通过。 In particular, the archived boolean collision_enabled=false now needs a truthful field/group/root source. The runnable pendulum input preserves the value and schema 1.0 and records its actual software-fixture estimate; do not copy that source as evidence for a real product. reference sources require nonempty detail, citation and conditions. Missing sources fail explicitly. New unschemed writes use 1.7, or 1.8 for new joint/articulation/coupling fields; legacy templates remain explicitly 1.0/1.1.
Physics requires only SimpleCADAPI directly; hatchling builds wheels, and pytest/jsonschema are test dependencies. Physics does not import the USD add-on. The USD physical path exchanges metadata.sca_physics and directly imports physics validation/geometry modules, so its optional physics extra pins 0.1.8rc1. Isaac/PhysX are external simulation-validation environments. A raw package with no embedded physics can use USD alone, preserving the exporter's existing legacy defaults.
Geometry-only users can upgrade USD alone. Existing physics 0.1.8rc1 users can retain it and update/re-provision USD to 0.1.8rc2. For older physics installations, prepare the matching reader/peer first, check it, then switch authoring to 0.1.8rc1 before writing schema 1.8. Prefer a fresh isolated home. Missing/mismatched physics is rejected rather than silently discarding metadata; unknown schemas are rejected. See upgrade steps.
Use a short state/runtime root on Windows: the tested roots are personal-workspace/results/arp-20261025-162555/s (standalone USD) and /p (paired), with a for add-on home, s for skills and runtimes for venvs. Deep paths failed while installing the SDK's Jedi dependency; no general maximum-length guarantee is made. Two external CAD-FEM checks, Isaac/PhysX behavior, other environments and all historical version combinations remain unverified. Installation/export success does not establish solver behavior or material accuracy.