Checking

Independent intent

Requirements describe the user’s needs independently of the model and its selectors. vxl check admits syntax and types; only a build obtains geometric evidence. For each delivered exact part, read its terminals[].structural_gate and measures together. The top-level structural_gate is one representative subject, not every part's result; each terminal gate names its own subject and GAR-bound step_digest. If exact-solid admission fails, inspect summary structural_gate and warnings; solid_count is not_measured with structural_gate_failed even when the raw count matches its nominal. If structural_gate.outcome is pass while root_exact and all_exact are false, read admission_rule, uncertainty_mm, and each status explanation. The bounded-tolerance rule admits only a certified curve-on-surface deviation at or below cap_mm; each edge status carries that certificate and comparison. A face unorientable_shape row names the edge context(s) from which that face status was derived. Per-status admitted_by appears only when the gate passed; a failed row keeps its diagnostic certificate without describing the context as admitted. These fields explain the existing admission result; they do not weaken or replace exact-solid admission. Session terminal mass properties use the same admitted copy as verification probes; a raw checker status alone does not imply that this copy is invalid. Refused admission remains unmeasured; standalone part mass-properties has a separate contract.

Requirements

Required fields for the conventions card

Each row also needs id and kind. subject names the delivered subject; operands names a pair. Alternatives shown with | are exclusive. See the generated reference for optional fields and detailed constraints.

Requirement cookbook

Each exact feature requirement locates one feature. For delivered mesh kinds use the mesh card. A planar_face / std.datum_plane is a plane: several coplanar faces (feet, a patterned part, a face split by a groove) are measured as one. normal is outward from the material; on a pocket or groove face it points into the void (groove floor: +z). A build row opposite_normal_at_station means: reverse normal. There is no expect field for feature locator cardinality (VXL-R601); component_count and enclosed_cavity_count use count. Use near or requirement at_each to disambiguate. Defaults materialize at check time.

Feature to requirement table

Feature → statement → the requirement that catches it being wrong. "Catches" means a build with that mistake does not RELEASE. Every exact part also takes solid_count and closed_delivered_mesh; mesh topology uses component_count instead of solid_count.

A counterbore crossing an exterior cone chamfer can measure on raw-exact geometry when its complete upper wall boundary is certified on the top plane and exterior cone, and its planar floor rim is complete. blind.mouth is the highest boundary station; evidence records the mouth station range. The current proof covers positive Z mouths with a parallel, off-axis cone. Interior pocket floors, B-spline hosts, unproven edges and additional wall trims refuse.

Measurement card

Measurement card: outer_diameter needs diameter, principal axis, axis_at and span:{from,to} equal to one maximal full-turn band of the observed outward cylinder wall (within boundary tolerance), not an arbitrary sub-interval of a band. A band is a connected station interval where the validated chart cells cover the whole turn exactly once; it ends at a full circular ring or at a retained boundary station where coverage becomes partial. A plain complete wall has one band equal to its full axial extent. With several bands, the authored span selects the matching band; if none matches, the row is a measured Fail and reports every observed band. A later Boolean may therefore leave a measurable intact band even when it notches another part of the same wall. The candidate's existing wall_incomplete classification is retained; nonempty bands make only the matching OD span measurable. Unsupported non-line trims remain wall_trim_unsupported for OD. Plain through-hole measurements also admit exact residual inward walls: circular/generator mouth recesses need an intact full-turn band and observed end arcs; curved interior interruptions need two complete terminal rings. The actual un-eroded cylinder volume must be clear. If this clearance check overlaps material, a residual wall alone does not prove a closure: the row is not_measured / native_proof_indeterminate, with observed stations and full-turn bands locating the uncertified region. A proved blind floor inside the authored window still fails. Explicit mouth-style expectations still need their complete opening proof. Through-hole candidate groups intersect their authored station window; the whole connected wall remains in the evidence. Coverage rejection and actual remaining faces stay visible even when the carrier and observed stations pass. For a grip at z=20 with length 56 ending at the guard's bottom face z=76, write the whole maximal band:

{"id":"r_grip_od","kind":"outer_diameter","subject":"dagger","diameter":24,
 "axis":"z","axis_at":[0,0,0],"span":{"from":20,"to":76}}

sharp_boundary and finishing_run need independent between:{first:{planar:{normal,at|through}},second:{planar:{normal,at|through}}} and run:{axis,from,to} with increasing endpoints; no names or nested near. A finishing run adds exactly one finish:{fillet:{radius,tol?}} or finish:{chamfer:{distance,tol?}}. Every relevant segment must qualify, and interior gaps fail; local size rows do not prove full coverage. A blind slot uses blind:{mouth,floor} instead of through; its complete planar stadium floor and empty observed prism are measured. Slot/OD boundary defaults to position; slot boundary is positive, below width/2 and half blind depth (R689). Equal blind mouth/floor stations first report R611 at blind; change one station to the intended open end or floor, since no positive tolerance can create depth. Position may be zero with explicit positive boundary. Complete exact-analytic through slots also measure under bounded-tolerance admission when U is certified: positions/stations expand by U and widths/diameters/lengths by 2U. A tolerance boundary crossed by that interval stays indeterminate, not measured. End-radius selection uses width/2 and half width tolerance plus U. A complete connected split bore is one measured group with every sorted member face; disconnected walls remain separate and unsupported trims cannot pass. Write mouths:[{at:<declared open station>}] for an explicit sharp opening; omit it only when no absence-of-modification claim is intended. Complete Sharp chains pass, proved modifications fail, and Unknown/incomplete chains stay not measured. See the tested mouth and split recipes. Sharp-mouth/split-bore corpus: 18 fixtures, six RELEASE and twelve designated-row HOLD in the recorded native measurements.

A sharp-run gap with proved detail.modified_intervals requires removing the chamfer, fillet or break-producing cut in parts[].steps to restore the raw crease over run.from..run.to. A finishing-run gap instead requires finishing the missing segment with the authored finish. Correct between or run only if they misstate the intended geometry. For ambiguous cylinder groups, narrow positive locate around axis_at only when axes differ; coaxial groups instead need the intended diameter and span or through/blind/band extent to distinguish them, or removal of unintended competing geometry. For per-probe resource limits, simplify topology in parts[].steps on subject; removing redundant requirements alone cannot repair that scan.

Full rules: VXL §7 (statements) and §10.1 (requirement kinds).

Requirement templates

Locate a requirement by geometry written from the document's params (normal with at/through), not by a construction face name: a requirement that names the faces its own step's selector used follows the same wrong build (VXL-W980).

minimum_wall.min is a lower threshold; the decision depth is min - tol with 0 <= tol < min. disk.margin must be positive and is additional clearance from the disk perimeter to every boundary of its selected face, not a thickness tolerance.

A near window includes its bounds and tests the candidate entity's centroid. It selects the whole entity and never clips it. It does not change measurement tolerances.

hole.axis accepts a principal direction token or a nonzero 3-vector. Stations are signed distances dot(point, normalized_authored_axis) from the part origin along the axis as written. The verifier canonicalizes the axis (first normalized component above the 1e-12 direction tolerance positive) and negates through, band, blind.mouth/blind.floor, mouths[].at and countersink.at stations when it flips, preserving the authored mouth/exit order. Zero, degenerate or non-finite vectors are VXL-G301. Hole operations retain oriented drill directions. For axis:[1,0,1], stations are (x+z)/sqrt(2): include the bore's translation in through/blind/band, and give any point on its line as axis_at; its axial component is ignored. Diameter, position and boundary tolerances apply as for principal axes; the complete cylindrical-wall proof is still required. Direction is a strict locator predicate, so a 2° wrong axis can report not_measured/no_cylinder_in_window, while a uniquely located, proven bore with wrong diameter, position or nearby stations reports its actual values and fails. Through-hole and band discovery requires overlap with the authored station interval; a wholly disjoint interval can also report no_cylinder_in_window.

hole.blind names its open end and floor as {"mouth":<len>,"floor":<len>}. A slot names 3D end-centre points with from and to, a width, an axis, and exactly one through:[from,to] or blind:{mouth,floor}. Endpoint components along axis are ignored. The retired positional hole extent is an error (VXL-R674).

Reserved gap kind (reported unsupported, HOLD when required): global_wall. opening has a closed mesh-only payload (mesh card); it is refused on an exact subject. Kinds that used to be reserved are now measurable: thread, helix, gear_teeth, gear_mesh, slot, counterbore, blind_hole, fillet_radius_general, contact_clearance, chamfer_size, feature_distance and text. The spellings counterbored_hole, countersunk_hole, fillet, contact and chamfer are refused as removed aliases (for countersunk_hole write kind: "hole" with a countersink style; countersink.at is allowed only on a through hole). thread, helix and material_region are measurable kinds, not reserved. For material_region, author a cylinder {origin,axis,radius,length} or a right-handed box {origin,x,y,z,size}, expected state:"material" or "void", and positive boundary_clearance. Complete planar/cylindrical boundary exclusion and an actual interior classifier are required; unsupported carriers, incomplete proof and exhausted fixed proof budgets keep required rows at HOLD. A wrong interior state after complete exclusion or a certified boundary witness FAILs. Any other kind is VXL-R602.

Sheet requirements

Use the complete two-bend bracket for both requirement shapes. State the intended final geometry independently of construction names. Neither requirement measures the authored K factor.

• bend locates one connected group of coaxial cylindrical skins in reopened STEP. Give the delivered subject; axis:{at,dir} and window:{axial:[from,to],radial:[inner,outer]} in the subject frame; a perpendicular unit radial start; expected inner radius, radial thickness, and positive angle from flat (at most 180 degrees). Axial stations are signed from axis.at along axis.dir; positive sweep follows the right-hand rule. The window selects the entire connected group; optional span:[from,to] restricts the measured axial band. Radius and angle do not select candidates. Zero or multiple groups are non-passes. Complete coverage and tangent planar joins are required; proven gaps or duplicate coverage fail. Unsupported trims, incomplete census or exhausted budget remain non-passes. Optional tol:{radius,thickness,angle} defaults to 0.05 mm, 0.05 mm and 0.1 degree; length tolerances must be positive and at most 1 mm, angle tolerance positive and at most 5 degrees. At most eight bend/partition census rows are admitted per build.
• sheet_thickness needs subject and positive thickness; optional absolute tol defaults to 0.05 mm and must be nonnegative and strictly less than thickness. It checks whole-subject modeled gauge in the reopened STEP: paired planes, coaxial cylinders, cones (parallel generatrices at normal distance t; same-station radius difference t/cos(beta)), concentric spheres (radius difference t), and ring tori (same centre circle, minor-radius difference t), matching whole 3D trimmed boundaries and ruled side closures. Wedges, extra bosses, mismatched trims and unpaired finishing faces fail. Unsupported surface laws, unsupported boundary laws or incomplete acquisition are not_measured; differently segmented partner boundaries remain non-pass. It does not assert a global minimum distance between arbitrary points, and works independently of construction names or whether the part was made with sheet.
• Fidelity: a sheet whose outline crosses a strip obliquely or with a line/arc chain is built in the certified bounded profile (check summary sheet_shells[].fidelity = certified_bounded). On such a sheet sheet_thickness, flat_pattern and a bend that selects a bounded bend are not_measured with reason bounded_geometry_requires_bounded_fidelity until you add "fidelity":{"bounded":{"max_deviation":1e-6}} (a positive length of at most 1e-3 mm; the certified target is 1e-8 mm). They then pass only when every certified fold bound is at most that allowance and every exact clause holds; the report shows certified_bound_mm. Leave fidelity out on exact sheets and on bend rows for exact bends (hem, jog, corner, bead bends beside a bounded tab stay exact rows).

Keep-out recipes

A keep-out is a part with role:"keep_out". It is verified, never delivered; acceptance is forbidden. Author it in the same frame as the request, then write a clearance requirement against the deliverable.

Stand-off rule. Touching counts as a collision. Start every keep-out more than clearance.min away from the seat face, or, when the two are meant to touch there, declare that plane in the clearance's contacts and keep min positive. VXL-W930 fires for any clearance whose operands meet on an undeclared plane, or whose declared contact the predicted boxes do not meet (static, predicted boxes only; silence is not measured proof).

Evidence grades

Exact

Exact evidence proves only the measured claim on its named subject. A static check is not a measurement.

ConservativeBound

Under mesh_conservative_v1, Exact PASS or a safe-side ConservativeBound may pass. Keep each measurement’s admission and locator limits from the mesh card.

Estimate and diagnostic-only

An Estimate never satisfies a required check. Compact replies, entity filters and diagnostic previews never decide RELEASE. Required Unknown, incomplete admission and exhausted budgets hold.

HOLD and repair

Read report/summary.json and report/revision-packet.json; fix one typed problem and rebuild within the gated loop budgets. Unresolved problems mean HOLD. Use vextcad vxl explain FILE --target ID for source expression dependencies; repair X101 using its bounded candidates (compact replies show the first candidates), and use Q501 did_you_mean only as spelling help.

For tilted hole hosts, rounded decimal coordinates can tilt a face beyond the frozen 1e-12 direction-component tolerance and cause host_adjacency_invalid or a mouth/floor host refusal. Use exact VXL expressions such as "20mm * sin(5deg)" and "20mm * cos(5deg)", or construct the face by a rotation. Increasing requirement tolerances does not relax this host-normal check.

Traps

Each line is a trap with the code it raises. vextcad vxl explain CODE prints the full rule.

Final-file checks

Output contract

• Exactly one authored source file: <name>.vxl.json, schema: "vextcad.vxl.v1", units mm and degrees. Native delivery files (such as STEP, STL or 3MF) are separate outputs produced by a build.
• Prefer composition: define a reusable shape in defs[] and use it, use at_each for statements and each for array entries, and use the sealed std library (declare "std": "vxl-std-2") for screw holes, tool access and datums. A use expands in place at check/build time; the expanded form is what runs, and no private __ id is ever writable.
• Write the compact form: omit title, notes and every field that equals its default; use typed functions for repeated formulas, variants[] for named finite override sets, and define a defs[] fragment when the same group of statements would otherwise appear three or more times.
• A missing fact is blocking when different answers give geometrically different parts or it is an interface dimension of something the user owns. Ask via questions[]; check never blocks on it.
• If you reuse a standard dimension, declare the source in assumptions[]; a length param whose id starts with head_, nut_, washer_, screw_, bolt_, thread_ or insert_ and is not sourced is VXL-W960 — take it from a std_ table, record it, or rename it.
• Run vxl check and read result.ok, result.errors, result.warnings, and result.notes until clean before uploading. Never present a document you have not checked.

Executable facts

The stdlib test instructions cover check versus measure, a missed hole, selector cardinality, Estimate/HOLD and compact HOLD. The 20-document manifest uses existing handwritten examples; check success makes no new build verdict claim.

Delivery decision

Every required need must have acceptable measured evidence. Read the actual label and cell; macOS arm64 development builds remain HOLD. Deliver HOLD files with that label and unresolved questions visible; only an obtained RELEASE may be called RELEASE.

Conventions card

Paste-ready prompt card: CONVENTIONS.md. std library: STD.md; the reference states each rule once.

Examples

• req_chamfer_size
• req_fillet_general
• req_sharp_boundary

Print deliveries automatically receive required assembly and AMS slot checks based on the authored composed parts and configured presets. A scene export directly targeting a scene import automatically receives a required byte-exact check; edited exports do not. These checks appear in the verification report and missing observations are nonpass. Do not author print_assembly, ams_slots, or scene_export_exact requirements. scene_reopen_equal remains an authored comparison of selected operands and fields.

For flat_pattern, deliver distinct formed and flat subjects from one part; the flat binding needs the capability retained by unfold. State a world anchor on the fixed planar skin, an independent default k_factor in [0,1], required scope:"full" or scope:"developable_regions", and optional tol (0.001 mm by default, at least 1e-9 mm). Each optional bends override uses an independent axis + window locator and K, and must find exactly one measured bend. Read the brep_flat_pattern_partition clauses: both reopened STEP censuses, whole gauge, fold tree, signed line/circle boundary equality and bend-table bijection must pass. Output-byte readback alone does not prove development. R870–R879 explain static refusals. Forms require developable_regions and independent world masks[].form locators for every complete form (dimple centre/normal/radius window or capsule end centres/normal/ half-width window). Masks retain the whole gauge proof, cover both skins, and must match measured forms and flat footprints one-to-one; missing/extra/wrong masks FAIL. Coverage is partial, FORM contains closed tangent boundaries, and the flat body is a nominal layout. full with forms stays non-PASS. See flat-pattern masks.