This browser-only viewer opens canonical .scadpkg product packages (package schema 3.0) without importing SimpleCAD, Python, or OpenCascade. The loader validates package.json, the exact member closure (definitions/, occurrences/root.json, blobs/, projections/scene/scene.json), and the embedded evaluated scene before parsing GLB or entity assets. It rejects older package schemas, standalone Scene ZIPs, and any package with missing, extra, length-mismatched, or hash-mismatched members. Product definition ZIPs and feature-graph archives are integrity-checked as package blobs but never re-packed, because the viewer renders exclusively from the scene projection.

npm install
npm run dev

Open http://localhost:5173/, click Open .scadpkg, and select a package written directly by the functional capture API:

scad.capture(result, "out/product.scadpkg")

The same file can be dropped directly into the viewport.

The file picker accepts local .scadpkg product packages only. The viewer does not load packages from URL query parameters or require a built-in case registry.

The second entry, re.html, is the interactive reconstruction studio: a human annotates a STEP target, an agent reconstructs from those annotations, and the studio displays the rebuilt result next to the original. See docs/skill/references/workflows/reverse-engineering-studio.md for the full agent-side loop.

# from the repo root — binds 127.0.0.1:7170 and opens the studio
uv run python -m viewer.server <case_dir> --daemon

The case directory must contain the STEP target (*.step/*.stp); the server synthesizes the same GLB + entity-sidecar scene projection packages carry, so face/edge/vertex picking works identically on both sides. The rebuilt side loads the agent's captured v3 rebuilt.scadpkg through the normal package loader. During development, npm run dev proxies /api to the server port.

Annotation happens in a free-form composer: picked entities and operations land as inline color-coded chips (serialized as [face:12](face:12) / [fillet](op:fillet)) alongside plain text; type / for an operation autocomplete. The operation registry is markdown — one file per tip in viewer/server/operations/ (frontmatter label/category/api/reads/doc_refs + hint body), editable without code changes; referenced tips travel inside the submission as operation_context. The rebuilt panel shows the package's feature DAG and the syntax-highlighted, self-contained rebuild source with feature-to-source line reveal.

Governance: the studio UI only selects and describes — it never edits geometry. Only the browser writes re_work/submission.json; the agent waits on it via uv run python -m viewer.server <case_dir> --wait-only and writes artifacts (rebuild.py, rebuilt.step, rebuilt.scadpkg, comparison.png, evaluation.json) that the UI polls. Every event lands in re_work/session.ndjson as the training record.

The presentation layer is a standalone component: BRepRenderer renders a scene-2.0 package (the GLB faces + line edges + entity sidecars that both the original STEP side and captured .scadpkg packages carry) with no dependency on any host page. It provides image-based studio lighting (PMREM RoomEnvironment + one key light), GTAO ambient occlusion (tuned to the model's world scale on every fit), a free trackball camera (no rotational poles, FIT restores the canonical Z-up and kills inertia), and CAD-style edge display — edges tessellate tighter than faces, and seam/degenerate edges are split into their own visuals and hidden by default.

import { BRepRenderer } from './renderer';

const viewer = new BRepRenderer(hostElement, { ssao: true, seams: false });
await viewer.loadScene(files);     // scene-2.0 files from a .scadpkg or the re-studio server
viewer.setSeamsVisible(false);     // toggle seam/degenerate edges
viewer.setEdgesVisible(true);
viewer.setSSAO(true);
viewer.frame();                    // canonical fit

Selection and annotation are deliberately out of scope: src/scene-view.ts composes BRepRenderer and adds raycast picking (face/edge/vertex), selection modes, and annotation marks. Embed BRepRenderer alone for read-only display; build interaction layers on top of it.

The Components tab shows the evaluated occurrence hierarchy. Select an occurrence to inspect its definition, visibility, and evaluated body data. The visibility control on each row hides or shows that occurrence.

The Features tab federates the immutable feature DAGs embedded by every part and nested assembly definition. Selecting a feature shows its operation, definition-local identity, inputs, outputs, parameters, source spans, and linked geometry. Connector and joint selections resolve through the package indexes to the exact producing feature when that evidence exists.

The source panel lists the content-addressed source snapshots embedded by the definition closure. Selecting a mapped feature opens the exact source asset, scrolls to its recorded line range, and highlights that range without reading files from the local machine.

Select components, solids, faces, edges, or vertices in the viewport to inspect evaluated geometry and measurements. Geometry selections link back to the feature DAG through stable definition, node, output-slot, and topology evidence.