Implementation gaps and next steps ​

This inventory summarizes verified user-facing behavior and durable capability limits. It is reconciled against the implementation and focused tests; PR and release state are tracked in GitHub. The remaining gaps are ranked by product value and implementation dependency, not by unused OCCT API surface.

Shipped capabilities ​

These are implemented and should not be filed as missing features:

  • Exact B-rep volume, surface area, centre of mass, and bounds are available through shape properties. Mesh-backed imports report tessellated precision.
  • Edge and face measurements, minimum distances, and planar-face angles between entities are exposed through /measurements and the TypeScript and Python clients. Mesh imports remain limited to their tessellated geometry, and unavailable measurements include a reason.
  • Interference checking is available through the engine, the REST API and the editor's scene list, with an AABB candidate prefilter and bounded pair count. Wall thickness is available as a sampled estimate with its sampling method disclosed. The editor runs both in its CAD worker on the same engine code (cadAnalysis.ts).
  • STEP imports can expose bounded product names and nested stepAssembly hierarchy metadata in shape summaries. Extraction is limited to inputs up to 200 solids and 8 MiB, with at most 2,000 hierarchy nodes and depth 32. POST /explode rebuilds nested editable project groups when every exact solid maps unambiguously to a source occurrence using the imported GLB geometry and source hierarchy. Otherwise it falls back to independently selectable flat solids. Leaf solids retain project-space placement, stepComponent occurrence identity, and root-to-component ancestry through .skf round trips. STEP export writes grouped project parts under a single assembly level, encoding nested group paths in product names; on reimport, those names can reconstruct nested groups when solid-to-occurrence matching is unambiguous. Native nested STEP hierarchy export and STEP transform editing are not implemented.
  • Kernel-backed hidden-line projection, scene SVG, section SVG, and section DXF exports are implemented. DXF requires an explicit section plane.
  • Baked mirrors, per-face color persistence, and per-triangle 3MF colors are implemented. GET /faces exposes stable application-owned IDs alongside compatibility indexes; colors use those IDs and survive project round trips. IDs and colors survive shape-parameter edits and supported CAD treatments when faces can be matched uniquely. For parameter edits, uniquely occurring cones, spheres, tori, and cylinders can retain identity when their sampled normal changes; repeated curved surfaces remain unmatched. Fillet and symmetric-chamfer operations use OCCT face history for unique one-to-one modified faces. New, generated, or ambiguous faces get fresh IDs and do not inherit colors. Viewport and 3MF previews map B-rep triangle groups to the same identities. Numeric face indexes remain supported for older projects and callers.
  • A bounded draft-prism operation is available in the shape inspector, over REST, and in the TypeScript and Python clients. It accepts a retained straight, single-loop sketch extrusion and stores exact geometry plus its angle and original extrusion frame/height. changeShape can update the angle by sketchSourceId; source profile edits reapply the draft and recompute retained boolean ancestors atomically.
  • Face-based drafting is available in the shape inspector for exact B-rep solids, with a selector for all six signed local CAD pull axes. In the editor the face for a draft or colour is picked by hovering and clicking it in the viewport, which maps the hit triangle through the mesh's B-rep face groups; the Faces panel's numbered stepper remains the keyboard fallback. The engine canonicalizes the selected direction before invoking the kernel and maps the result back to the original orientation. Measured support is geometry- specific: on the unrotated editor-plane extrusion, faces 0, 2, 4, and 5 are verified at ±5° along +X; faces 0–3 at ±5° along +Y; and faces 1, 3, 4, and 5 at ±5° along +Z. A +90° Y-rotated fixture accepts face 0 at ±30° along +X, and a -90° X-rotated fixture accepts face 2 at +10° along +Y. On a 10 mm box, faces 0–3 are verified at ±5° and ±30° along +Z and -Z; face 2 at +5° along +X; face 0 at +5° and +30° along -X; and face 2 at +5° and +30° along -Y. The box face 0/+5°/+X case is rejected because the pull axis is parallel to that face. These are measured cases, not broad support for other faces, solids, or angles. Other unsupported combinations return a localized error. The editor keeps a face or prism draft on an eligible single-loop sketch extrusion as the same retained feature the REST API writes, built by the engine's browser-safe sketchFaceDraftKernel; its arbitrary-shape draft remains baked. The engine/API can retain one face draft on a sketch extrusion, single-solid sketch sweep, or plain single-region full-turn sketch revolve. Revolves use GET /faces?topology=exact so analytic face selection does not change the default tessellated listing or its compatibility indexes. It stores the selected source face ID, signed pull axis, angle, and matching evidence. For a straight-line, single-region, no-hole extrusion side face, .skf also persists its exact sketch segment ID and profile edits replay against that segment even when its normal changes. Missing, removed, or ambiguous segment matches fail atomically. Caps and other extrusion profiles, sweeps, and revolves continue to use a unique saved planar-normal match; missing or ambiguous matches and failed dependent booleans roll back atomically. Original source frames and resized revolve scales are retained. Partial-turn, helical, and multi-region revolve drafts are refused. A draft on an extrusion nested in a retained boolean group survives .skf round trip and replays after a source-profile edit while preserving the group ID and committing one atomic write. A single-loop sketch extrusion or a single-section, no-hole sketch sweep may retain one all-edge fillet or one symmetric 45° all-edge chamfer after one face draft; .skf round trips preserve the sequence and source-profile edits replay the draft before the treatment atomically. A single-loop sketch extrusion supports one all-edge fillet or one symmetric 45° all-edge chamfer after a face draft; selected-edge treatments, non-45° chamfers, and additional treatments remain refused. Sweep drafts with multiple sections or section holes, selected-edge treatments, non-45° chamfers, and additional treatments remain refused. A plain single-region full-turn sketch revolve may retain one face draft followed by either one symmetric 45° all-edge chamfer or one all-edge fillet; profile and setting edits replay source, draft, then treatment atomically. Adding a second treatment, a prism draft, or a shell to a face-drafted shape remains refused before writing.
  • The Sketch workspace supports planar sweeps with one or more closed section loops and one open spine on the derived orthogonal plane. Nested section loops become holes; disjoint loops become separate solids. Spine points and cubic Bezier handles can move along the section plane's third axis, with independent handle depths. The editor retains the source profile for reopening and editing. POST /shapes accepts kind: "sketchSweep"; the engine and TypeScript and Python clients can create sweeps and replace sketchProfile through PATCH /api/v1/shapes, rebuilding geometry while retaining shape and source IDs. PATCH /shapes can target a sketch sweep by its persisted sketchSourceId or by output shape ID; it updates the source profile and rebuilds its dependent sweep before writing the project. Invalid profiles leave the persisted source and sweep unchanged. A profile rebuild receives fresh face IDs and drops face colors because old faces cannot be assumed to correspond to the new profile. One supported all-edge fillet or symmetric 45° chamfer is replayed against rebuilt topology; unsupported or ambiguous treatment histories fail the edit atomically. A single-section, no-hole sweep may also retain one face draft followed by one all-edge fillet or symmetric 45° all-edge chamfer; its .skf representation and source-profile edits replay sweep, draft, then treatment, while multiple treatments and ambiguous source faces fail without a project write. Changing the retained face-draft angle, signed pull axis, or both together on that treated sweep replays source, draft, then treatment atomically; .skf round trips and later profile edits preserve the updated values, treatment, and IDs. Invalid axis or downstream treatment replay failures roll back without a project write. Source-face reselection and unsupported sweep geometry/treatment combinations remain refused.
  • .skf stores source-sketch nodes and feature inputs for sketch extrusions, revolves, sweeps, and boolean groups. Source profiles, operation parameters, and dependency links survive project round trips. Profile edits rebuild the corresponding solid while retaining its shape and source identity. Editing a sketch-backed extrusion or sweep through its persisted source ID also recomputes retained boolean ancestors bottom-up, preserving output IDs and placement and writing the new source and dependent geometry atomically. A source-driven revolve profile or operation-setting edit (for example, its side count) follows the same bottom-up rebuild and atomic-write path. Every edge treatment is recorded on the shape, whether the editor or the engine's treat operation (REST POST /treatments, MCP) applied it. A sketch extrusion, sweep, or revolve whose record is one all-edge fillet replays that fillet after a source-profile edit against rebuilt topology, without carrying edge indices across the edit. One recorded symmetric 45° all-edge chamfer follows the same replay path on those source kinds, with treatment history and the current eligible-edge count rebuilt from new topology. Plain full-turn revolve fillets and chamfers, all-edge or selected-edge, are cut from exact CAD geometry rebuilt from the retained profile, and the edge listing and edge measurements number that same exact solid (#347); a resize is applied to the section before it is turned. They currently require exactly one closed profile region; partial-turn, helical, cored, multi-region, and unevenly stretched revolves have no exact solid, so their treatments and edge listings are refused rather than run on facets. Revolve setting edits also attempt replay and roll back if the new topology cannot accept the treatment. A selected-edge fillet or chamfer on the cap edges of a straight, single-region, hole-free sketch extrusion records each edge by its sketch segment and cap (sourceEdges) and replays by that identity after a source-profile edit; a removed, missing, or ambiguous match, or an edit that leaves the boundary, fails without a write (#350). The editor's Fillet/Chamfer tool records and replays the same lineage through the same matcher in its CAD worker (#540). Side (vertical) edges, drafted, mirrored or already-treated extrusions, and sweeps and revolves have no selected-edge lineage yet. A source edit on a shape whose record holds a selected-edge treatment without lineage, a non-45° all-edge chamfer, or multiple treatment steps, or on a shape that was shelled (the shell is recorded too), is refused without a project write rather than rebuilt without them. Draft/treatment combinations outside the supported order below and treatments on other source operation types remain unsupported. One retained prism draft followed by one all-edge fillet or symmetric 45° chamfer is now supported on a sketch extrusion; source-profile and draft-angle edits replay the draft first and treatment second, refreshing history and eligible-edge counts. Adding a prism draft after a treatment, selected-edge treatments, multiple treatments, and combinations on other source kinds remain unsupported. Invalid source profiles and dependent booleans that no longer remove material leave the project unchanged. Other downstream operation types do not yet participate in a general recompute graph.
  • Coincident, horizontal, vertical, perpendicular, parallel, fixed-distance, and fixed-point sketch constraints are supported, including .skf persistence and TypeScript profile types. A fixed point anchors a sketch point to workplane coordinates and can remove global translation freedoms. Perpendicular and parallel relations take part in the bounded coupled solve and local degree-of-freedom estimate. Point drags keep directly dragged points anchored and report unsatisfied constraint IDs. The inspector also estimates local degrees of freedom from the supported equations' Jacobian rank.
  • OBJ import is supported alongside STL, SVG, and STEP, and imported source assets are preserved in .skf projects.
  • Camera view orientation, target, and zoom are saved with the project and restored when it is reopened. Older projects without camera data retain the default view.
  • Server-side project reads regenerate source-backed STEP meshes with the server kernel, so STEP imports can reopen from server-backed storage.

Relevant implementation seams include serverCadProperties.ts, serverCadMeasure.ts, cadAnalysis.ts, serverCadInterference.ts, serverCadThickness.ts, serverStepExplode.ts, stepAssemblyHierarchy.ts, serverCadProjection.ts, and serverCadSection.ts in packages/sketchforge-engine/src/.

Remaining gaps, ranked ​

1. Dependency-ordered parametric recomputation ​

This work is tracked by epic #327: Parametric recompute correctness and editable feature history. See that issue for current scope, supported recompute paths, and remaining implementation gaps.

2. Broader and editable drafting ​

Face drafting is selectable along local X, Y, or Z, but verification covers only the fixture/face/angle combinations listed above. Other face orientations, solid classes, and angle ranges are unverified or may be rejected by the kernel. The editor's general face-draft results remain baked; on an eligible sketch extrusion it now creates and edits the retained face and prism drafts (#384). The engine/API retains one editable face draft on a sketch extrusion, single-solid sketch sweep, or plain single-region full-turn sketch revolve. Eligible straight-line, single-region, no-hole sketch extrusion side faces replay by exact source segment identity, including when the normal changes; other supported faces still replay only when exactly one planar face matches the stored local normal. Missing or ambiguous matches fail atomically. One symmetric 45° all-edge chamfer or one all-edge fillet may follow a face draft only on a plain single-region full-turn sketch revolve; profile or setting edits replay the revolve, face draft, then treatment atomically and refresh treatment history and eligible-edge counts. .skf round trips preserve this supported sequence and allow replay after import. Face drafts remain incompatible with prism drafts and shelling. Edge treatments are supported in the explicitly bounded full-turn revolve sequence above, plus one symmetric 45° all-edge chamfer after a face draft on a single-loop sketch extrusion, and one all-edge fillet or symmetric 45° all-edge chamfer after a face draft on a single-section, no-hole sketch sweep. Profile edits replay source, draft, then treatment; .skf preserves those sequences. On the supported sweep, changing the retained draft angle, signed pull axis, or both together replays the treatment atomically, preserves source/output/source-face IDs, and refreshes treatment history and eligible-edge counts. A .skf round trip followed by a source-profile edit retains both updated values. Invalid axes or failed replay roll back without writing. Source-face reselection, multi-section sweeps, sweeps with holes, non-45° chamfers, and selected-edge or multiple treatments remain refused. Other face-draft / treatment sequences remain refused. A retained prism draft on a sketch extrusion can be followed by one all-edge fillet or symmetric 45° chamfer; source-profile and draft-angle edits replay the draft before the treatment. Adding a prism draft after an edge treatment remains refused, as do selected-edge or multiple treatments on a drafted extrusion. Shelling remains refused when persisted draft or treatment metadata exists. On a single-loop sketch extrusion with one supported all-edge fillet or symmetric 45° all-edge chamfer, changing the retained face-draft angle, signed pull axis, or both together replays source, draft, then treatment atomically. .skf round trips and subsequent profile edits retain both values, treatment, and IDs; invalid axes or failed replay roll back without writing. An untreated retained face draft can be reselected by an ID from the original source-face listing only when that ID remains exactly once as a planar face in the current output. The source-face ID allowlist persists in .skf but is not returned in shape summaries. Generated draft-face IDs, ambiguous or missing IDs, reselection on treated shapes, and profile edits combined with reselection are refused atomically. Profile edits rebuild the allowlist from the new source topology rather than transferring IDs by CAD face index. Other source-face reselection remains unsupported; this bounded support does not define semantic lineage across arbitrary topology changes. Prism drafts are editable only as a retained angle on a straight, single-loop sketch extrusion. The editor creates and edits both retained features on an exact, untreated, unmirrored, unresized single-loop sketch extrusion, and replays them when the sketch is edited (#384); sweeps, revolves and every other shape keep the baked editor result. Other draft operations and general editable draft history remain unsupported. Broader fixture coverage should establish the supported geometric envelope.

On a plain single-region full-turn sketch revolve with one all-edge fillet or symmetric 45° all-edge chamfer, changing the retained face-draft angle, signed pull axis, or both together replays revolve, draft, then treatment atomically. Output, source, and source-face IDs remain stable; treatment history and eligible-edge counts are refreshed. .skf round trips preserve both values and allow subsequent profile and revolve-setting edits. Invalid axes or failed replay roll back without writing. Multi-region, partial-turn, and helical revolves remain refused.

3. Editable STEP assembly hierarchy and robust component association ​

The engine retains source occurrence IDs and ancestry on exploded solids when association is unambiguous, and persists that metadata through .skf. The identifiers describe a particular STEP source and may change when the source file or product structure changes. STEP export preserves supported grouped project parts as a single-level assembly and encodes nested group paths in part names; reimport reconstructs nested editable project groups from those paths when each exact solid maps unambiguously to an occurrence. POST /explode also reconstructs nested groups from source STEP hierarchy when association is unambiguous. If a solid cannot be mapped uniquely, the importer returns flat solids rather than a partial hierarchy. The STEP document itself does not retain native nested assembly levels, and STEP transform editing is not implemented. Full native hierarchy support still needs robust association across exporters and broader STEP fixtures.

4. Stable face identity across arbitrary topology changes ​

Stable IDs and color assignments survive shape-parameter edits and supported CAD treatments when the engine finds a unique match. Matching uses exact face B-rep or a unique planar support surface; for parameter edits, uniquely occurring cone, sphere, torus, and cylinder faces can also retain identity when their sampled normal changes. Fillets and symmetric chamfers can use OCCT's modified-face history for a unique one-to-one mapping. This is not a semantic identity contract. Split, merged, generated, repeated, or otherwise ambiguous faces receive new IDs without inherited assignments. General identity across arbitrary topology edits remains unsupported.

5. Broader sketch constraints and globally determined solutions ​

The solver supports coincident, horizontal, vertical, perpendicular, parallel, and fixed-distance relations with a bounded deterministic least-squares solve and a local Jacobian-rank estimate. Parallel constrains two segment directions to align, allowing either the same or opposite orientation; it does not align their offsets. The solver also supports fixed-point relations, which can anchor global translation. Without a fixed-point anchor, sketch placement retains two global translation freedoms; with an anchor, the solver can constrain placement. It does not guarantee global solvability or identify every nonlinear or second-order dependency. Degenerate zero-length distance geometry has no determinate degree-of-freedom report. Additional constraint types and robust global placement remain open.

Verification baseline ​

Focused coverage includes retained face-draft creation, .skf round trip, segment-lineage replay and rollback (tests/unit/faceDraftSegmentLineage.test.ts), selected-edge segment-lineage replay and rollback (tests/unit/selectedEdgeSegmentLineage.test.ts), source-profile replay, missing-match rollback, and dependent-boolean rollback (tests/unit/engineParametricRecompute.test.ts, tests/unit/faceDraftFilletGroupRecompute.test.ts, tests/unit/faceDraftChamferRecompute.test.ts, tests/unit/faceDraftFilletRecompute.test.ts, tests/unit/apiV1ShapeRoundTrip.test.ts), sweep creation and profile rebuilding (tests/e2e/sketchCadSweep.e2e.ts, tests/e2e/restApi.e2e.ts, tests/unit/apiV1ShapeRoundTrip.test.ts), source-driven extrusion and revolve recompute and boolean rollback (tests/unit/engineParametricRecompute.test.ts, tests/unit/apiV1ShapeRoundTrip.test.ts), sketch source and feature persistence (tests/unit/skfProject.test.ts), STEP hierarchy and component persistence (tests/unit/serverStepExplode.test.ts, tests/unit/stepAssemblyProject.test.ts), face-ID matching (tests/unit/apiV1FaceIdentity.test.ts), face-draft axis cases (tests/e2e/draftFaceEditor.e2e.ts), and sketch constraints (tests/unit/sketchConstraints.test.ts). These tests establish specific supported cases; they do not establish general kernel coverage beyond those cases. Recheck limits and surface coverage before raising them, especially for large STEP assemblies and static/offline builds.

Documentation version: 1.30.0 · Repository revision: 1cb9fee8dff4d394684c229dd67a21da539d167f · View source