0.2.7 Element Descriptors and Compatibility Preflight

WP03 installs a technical descriptor layer for the element families already present in QF Solver and a deterministic compatibility check before assembly and solve. It adds no element, formulation, material model or qualification.

Source-of-truth boundary

The descriptor answers what an element can technically route: topology, DOFs, faces, integration family, material/analysis/load categories, mass and recovery availability, backend restrictions and route restrictions.

qualification/0_2_7/capability_registry_v2.json remains the source of truth for maturity of a combination. Descriptor data must not be read as a qualification claim. SUPPORTED, TESTED, VERIFIED and QUALIFIED_BOUNDED remain distinct registry states.

Descriptors are available for BEAM2, MITC3, MITC4, TET4, TET10, HEX8, HEX20, WEDGE6 and DISCRETE. WEDGE6 describes the implemented technical elemental kernel, while its registry combination remains EXPERIMENTAL and no public qualified capability record is created.

Preflight contract

The public router runs a fail-closed preflight after analysis normalization and before assembly. It checks the element family, analysis, material, formulation/route, load categories and requested backend. Unknown or technically unsupported combinations return UNSUPPORTED_ROUTE. A known technical route whose registry state is EXPERIMENTAL or NOT_QUALIFIED is reported explicitly as EXPERIMENTAL_ROUTE or NOT_QUALIFIED_ROUTE; a qualified bounded registry combination is reported as SUPPORTED_ROUTE.

Results carry a deterministic status, reason code, reader-facing message and the normalized combination fields. The distinction is intentional: lack of qualification is not silently converted into technical support, and a missing technical route is not inferred from an element alias.

The compact access contract is exposed from solveur.compatibility through get_element_descriptor, check_compatibility, get_supported_analyses, get_supported_loads, get_maturity and explain_compatibility.

Evidence and boundary

Targeted evidence covers descriptor completeness, deterministic aliases, registry/descriptor consistency, supported and experimental route handling, explicit non-qualified handling, malformed inputs, unsupported loads and deterministic model preflight. Existing BEAM2, MITC3, HEX8, discrete/contact, analysis-feature and public API workflows remain green in the targeted set.

The WEDGE6 descriptor is limited to the experimental linear_static route with homogeneous isotropic material, the declared SciPy route, and the WP08-validated Gmsh Prism 6, nodal/body/surface-load and Gauss-point post-processing path. It does not declare modal/dynamic, nonlinear, contact or external-correlation support. This work package does not make the experimental route qualified or authorize a full regression or engineering V&V campaign.