content-workflow-physics

name	content-workflow-physics
description	Use with content-workbench when a long-running coding agent needs to infer physics properties, author USD physics schema, run simulation-backed validation, refine failures, and produce canonical physics artifacts and validation evidence.

content-workflow-physics

Use this skill with content-workbench when a long-running coding agent needs to infer physics properties for a USD asset, author physics schema, run simulation-backed validation, and produce canonical physics artifacts.

This skill owns workflow method. Workbench owns scene state, rendering, picking, optimization, edit mechanics, restore, export, and runtime validation APIs.

Workflow

1. Load the Workbench skill.
2. Start or connect to Workbench.
3. Inspect unoptimized component and topology evidence first. When optimizer settings are not supplied explicitly, choose them for physics authoring: preserve body, joint, articulation, collider, helper, and component roles; optimize only when it improves legal inspection or authoring targets.
4. Inspect logical components and topology. Keep visual evidence, collider targets, helper geometry, rigid-body roots, and joints as separate roles.
5. Resolve mobility intent before topology repair. Preserve existing topology when intent is absent or ambiguous. Apply only an explicit, digest-bound topology plan to a derivative asset.
6. Make exactly one physics decision per component. Existing colliders are preserved and targeted directly; visible geometry is a collider target only when the decision explicitly uses author_on_targets. Never target helpers.
7. Infer density, mass, friction, restitution, collision approximation, confidence, rationale, and quality warnings for each decision.
8. Write the V2 raw/physics_decision_patch.json and, when required by resolved mobility intent, raw/physics_topology_plan.json.
9. Apply accepted topology and physics decisions through Workbench APIs.
10. Run deterministic schema checks and runtime simulation validation. Treat initial pose discontinuity, excessive ground penetration, missing gravity response, and expected body-count mismatch as hard failures.
11. Render frames from the runtime recording.usda through Workbench's generic frame-sequence render API.
12. Write physics_behavior_assessment.json after visually reviewing the rendered simulation frames and runtime report.
13. Refine physics decisions when runtime or visual validation finds fixable issues.
14. Produce canonical artifacts and restore/export accepted edits when required.

Required Artifacts

• request.json
• raw/physics_decision_patch.json
• physics_assignments.json
• authored USD/USDZ with physics schema when the workflow claims a durable output
• physics_behavior_assessment.json
• validation_evidence.json
• runtime validation artifacts
• operation counts where available
• final summary
• trace/events where available

Runtime Validation Refinement

Runtime validation is part of this skill, not a separate workflow skill. ovphysx/runtime metrics are authoritative for hard failures. Visual behavior review can make an otherwise passing runtime result conditional, but it must not override non-finite trajectories, missing rigid bodies, runtime load failures, or other solver-backed failures.

After runtime validation, render the recording.usda with Workbench render-frames and review the frames for:

• parts visibly separating or moving independently when intended as one rigid body;
• no visible motion under gravity;
• implausible bounce, sliding, or settling;
• obvious interpenetration or tunneling;
• stale, blank, or misframed validation renders;
• mismatch between runtime metrics and visible behavior.

Write physics_behavior_assessment.json with status, checked_views, runtime_report, rendered_frames, issues_found, issues_fixed, unresolved_issues, and assessment_notes.

When simulation or schema validation reports fixable issues:

• preserve the previous decision patch;
• inspect affected prims, properties, body grouping, collider approximation, and trajectory metrics;
• apply targeted corrections through Workbench;
• rerun only the needed validation scenarios when possible;
• update physics assignments and validation evidence;
• stop when remaining issues are unfixable with available evidence/runtime support or when the configured iteration cap is reached.

Boundaries

Do not use the fixed apps/physics_agent pipeline as this workflow's engine. Learn from its property vocabulary, authoring rules, simulator contracts, and validation metrics, but keep the workflow agent-driven through Workbench.

Call Workbench inspect-components, inspect-topology, apply-topology-plan, apply-schema, and validate-runtime operations. The inspect-mesh-candidates route is V1 compatibility only and must not drive new workflow decisions. When the workflow needs visual review of a generated time-sampled recording, call Workbench's generic frame-sequence render operation with the recording as scene_path. A solver such as ovphysx may run in an isolated helper process behind Workbench, but the workflow agent should consume Workbench artifacts and metrics rather than importing the solver daemon directly.

Move reusable USD physics authoring, simulator execution, trajectory metrics, and validation evidence helpers into world_understanding when they are useful outside this workflow. Keep workflow-specific policy, schemas, finalizers, and repair rules in content_agent_workflows.physics.

References

• references/physics-policy.md
• references/output-artifacts.md
• references/runtime-validation.md