# Linear Static MITC4 Shell Release Report

## Metadata

- feature_id: `linear-static-mitc4-shell`
- source_requirement: `docs/requirements/linear-static-mitc4-shell.md`
- source_research: `docs/research/linear-static-mitc4-shell-research.md`
- source_formulation: `docs/formulations/mitc4-shell-formulation.md`
- source_numerical_review: `docs/numerical-reviews/linear-static-mitc4-shell-review.md`
- source_io_definition: `docs/io-definitions/linear-static-mitc4-shell-io.md`
- source_reference_model: `docs/reference-models/linear-static-mitc4-shell-reference-models.md`
- source_implementation_plan: `docs/implementation-plans/linear-static-mitc4-shell-implementation-plan.md`
- source_implementation_evidence: `phases/linear-static-mitc4-shell/index.json`
- source_implementation_report: `N/A`; the project Harness phase index is the implementation completion ledger for this execution
- source_correction_report: `N/A`; no final Build/Test, Reference Verification, or Physics Evaluation failure was handed to Correction Agent
- source_build_test_report: `docs/build-test-reports/linear-static-mitc4-shell-build-test.md`
- source_reference_verification_report: `docs/reference-verifications/linear-static-mitc4-shell-reference-verification.md`
- source_physics_evaluation_report: `docs/physics-evaluations/linear-static-mitc4-shell-physics-evaluation.md`
- audited_source_head: `820ba30c717b3d0e113775608e20dfd5fbc05d53`
- audited_branch: `feat-linear-static-mitc4-shell`
- status: `ready-for-release`
- owner_agent: `release-agent`
- date: `2026-08-13`
- release_boundary: internal FESA feature release readiness only; no publish, deploy, package, tag, commit, or external release was performed

## Release Scope

| item | included | excluded | notes |
| --- | --- | --- | --- |
| analysis type | One small-displacement, small-rotation `*STEP, *STATIC` | Multiple steps, geometric/material nonlinearity, buckling, modal, dynamic, contact, thermal | Existing factorize-before-load linear-static lifecycle is retained. |
| element type | Four-node source `S4` and `S4R` mapped to one full-integration `FESA-MITC4` path | `S3`, `S8`, `S8R`, continuum/solid/axisymmetric shells, MITC4+, MITC4/D, reduced integration/hourglass behavior | Source type is preserved as metadata; no Abaqus formulation-equivalence claim is made. |
| nodal degrees of freedom | Global `[UX,UY,UZ,URX,URY,URZ]`; 20 physical element coordinates plus four numerical drilling coordinates | Physical drilling strain/load/result channel | Director-parallel nodal moment is rejected. |
| material and section | Centered, single-layer, homogeneous isotropic linear elasticity with finite valid `E`, `nu`, and constant positive thickness | Composite/laminated or orthotropic sections, offsets, variable/nodal thickness, user orientation | Multiple valid materials/sections/element sets are allowed with exactly one assignment per element. |
| geometry | Valid four-node quadrilaterals and smooth shell patches with deterministic geometry-derived directors | Explicit normals/directors, shared-node sharp folds, hinges, shell-beam joints, calibrated distortion/warp thresholds | A physical fold requires duplicated source nodes. |
| loads and constraints | Nodal `*BOUNDARY` and global nodal `*CLOAD` on DOFs 1-6, subject to the drilling-moment projection rule | `*DLOAD`, pressure, gravity, body/edge/follower load | Output-request keywords in the allowlist remain warning no-ops. |
| authoritative output | HDF5 `results.h5`: nodal displacement/full residual, shell frames, generalized strain/resultant, bottom/middle/top in-plane stress, physical energy, equilibrium, verification metrics, diagnostics | Official CSV solver output, drilling output/energy, `S33`, pointwise `S13/S23`, nodal shell-stress averaging | HDF5 schema version remains `0` and is extended additively. |
| external acceptance | Read-only `reference/shell/shell.inp` and `reference/shell/shell displacements.csv`; `U1/U2/U3` blocking at fixed absolute `1.0e-5`; `UR1/UR2/UR3` warning-only at the same value | S4R artifact consumption; Abaqus reaction/stress/strain/resultant equality | Direct HDF5-to-CSV source identity mapping is authoritative. |

## Gate Evidence Inventory

| gate | source | expected status/evidence | observed status/evidence | verdict |
| --- | --- | --- | --- | --- |
| requirements | `docs/requirements/linear-static-mitc4-shell.md` | approved scope, acceptance criteria, tolerance and reference boundary | `approved`; requirements `001-072` are all `must` and covered without gaps | pass |
| research | `docs/research/linear-static-mitc4-shell-research.md` | approved evidence with applicability limits | `approved`; no research-owned blocking decision remains | pass |
| formulation | `docs/formulations/mitc4-shell-formulation.md` | implementation-ready current linear formulation | `approved-for-implementation-planning`; future nonlinear Section 15 remains explicitly non-executable | pass |
| numerical review | `docs/numerical-reviews/linear-static-mitc4-shell-review.md` | `pass-for-implementation-planning` | `pass-for-implementation-planning`; no current-scope blocker | pass |
| I/O definition | `docs/io-definitions/linear-static-mitc4-shell-io.md` | approved input/HDF5/comparison contract | `approved-for-implementation-planning`; exact S4-only acceptance boundary and fixed tolerance are present | pass |
| reference model | `docs/reference-models/linear-static-mitc4-shell-reference-models.md` | approved exact artifact inventory and row mapping | `approved-for-implementation-planning`; both declared files exist and match hashes | pass |
| implementation plan | `docs/implementation-plans/linear-static-mitc4-shell-implementation-plan.md` | approved TDD plan tracing every `must` requirement | `ready-for-implementation`; ranges cover `001-072` exactly once | pass |
| implementation | `phases/linear-static-mitc4-shell/index.json` at source HEAD | completed RED/GREEN/VERIFY execution | Steps `0-13` are `completed`; all 14 `stepN-output.json` records have `exitCode=0`; top-level phase is `completed` | pass |
| correction | final downstream reports and commit/Harness history | no unresolved implementation-owned failure | `N/A`; final Build/Test and Reference Verification classify correction handoff as `N/A`; historical pre-gate Step 13 retries are closed | pass |
| build/test | `docs/build-test-reports/linear-static-mitc4-shell-build-test.md` | `pass-for-reference-verification` | `pass-for-reference-verification`; clean MSVC x64 Debug build, focused `87/87`, `10/10`, `8/8`, full `144/144`, Harness Python `7/7`, zero warnings | pass |
| reference verification | `docs/reference-verifications/linear-static-mitc4-shell-reference-verification.md` | `pass-for-physics-evaluation` | `pass-for-physics-evaluation`; exact `294/294` row identity, blocking U `147/147`, UR warnings `0`, invalid rows `0` | pass |
| physics evaluation | `docs/physics-evaluations/linear-static-mitc4-shell-physics-evaluation.md` | `pass-for-release-agent` | `pass-for-release-agent`; equilibrium, reaction, direction, symmetry, recovery, stress signs, residual and physical energy pass | pass |

### Gate Consistency and Staleness Audit

- Every gate uses `feature_id=linear-static-mitc4-shell`. Build/Test, Reference Verification, and Physics Evaluation all identify source HEAD `820ba30c717b3d0e113775608e20dfd5fbc05d53`, which is the audited current HEAD.
- The requirements metadata value `current_product_state=requirements-approved-not-implemented` records the product state when the requirements gate was authored. It is not the requirements gate status and does not alter the later implementation evidence.
- Numerical Review values `implementation_complete=false`, `build_test_complete=false`, `reference_comparison_complete=false`, `physics_evaluation_complete=false`, and `release_ready=false` are explicit pre-implementation review boundaries. Later same-feature reports at the audited HEAD supply those downstream decisions. They are phase-time markers, not contradictory live statuses.
- No contract meaning, reference inventory, tolerance, or source identity in those earlier documents conflicts with the final reports. The phase-time markers are therefore nonblocking and are not silently treated as current completion claims.
- A separate implementation report is nonblocking under the current workflow because the Build/Test report explicitly declares `source_implementation_report=N/A` and points to the Harness index. The index records each RED failure, GREEN behavior, focused/full verification summary and completion timestamp, while all 14 generated step-output records have `exitCode=0`.
- A correction report is nonblocking `N/A`: Correction Agent reporting is required after a formal downstream failure handoff. The final formal Build/Test, Reference Verification, and Physics Evaluation gates report no such failure or unresolved defect. Historical implementation-phase retries and correction commits precede the clean independent gates and are closed by the final phase ledger and source HEAD.
- The Numerical Review metadata contains two historical commit references (`reviewed_head=cf769aa` and a downstream note naming `a058ef7`). This is a document-history inconsistency, but its mathematical verdict was re-audited against the current tracked requirements/formulation/I/O/reference contracts and independently exercised at `820ba30...`; it does not create a scope, tolerance, or acceptance contradiction.

## Evidence Hash Inventory

SHA-256 values are lowercase. The build-local HDF5 container is intentionally not a decision identity because valid regenerations can change raw container bytes; the deterministic projected ledger is the stable comparison evidence.

| evidence | bytes | SHA-256 | audit role |
| --- | ---: | --- | --- |
| requirements | 35,124 | `c8966f667ee42c3d35d0bf2f1bc1662a93784a2037d5b191b59793fb5ad66c64` | approved must-requirement baseline |
| research | 37,197 | `45f02291c8b2fdc7066cdb938cf6662a97dd3dceb9023fa743fe1c356a7970b4` | theory/benchmark/applicability evidence |
| formulation | 57,593 | `117932a112b2ad7f1cb6a8084304733fcd529a675a93cca6364c2f6a16c57cd0` | mathematical implementation contract |
| numerical review | 24,406 | `c82bd7b4f14f7664fb082d9a860dc443bf76571affa24caa8a7a9acfba04af1e` | independent formulation gate |
| I/O definition | 41,327 | `6f362b16625e61c85949648e6bc1f215c92ff31e99654f6efd9787b428dd54c4` | input/HDF5/comparison contract |
| reference model | 6,112 | `978e18485a627b6abf83373f74929cfe564952d29f68574e0cab75ef5e689c44` | exact S4 inventory and row mapping |
| implementation plan | 56,316 | `8d269455d0d5fe9bb9dc32f140d1ea6f105bab60ebfe73d368ad8c5225af6482` | TDD task/test traceability |
| Harness implementation index | 7,392 | `8c0a7369bc81fc7a12f9f3a49158a9534d4727b9a924c95b1ece7e915d16880d` | 14-step completion ledger |
| Build/Test report | 11,970 | `d261e13eb1c6dc20cf24f85ee97a3fcb6b667420486ad12725030e3eebf8dcd1` | independent MSVC/CMake/CTest evidence |
| Reference Verification report | 14,362 | `2c69814eeb265bd47672c46e17e2c63d55a0f8d834325c2b0d78e0500a83bade` | fixed-tolerance comparison evidence |
| Physics Evaluation report | 19,596 | `d753521c73ac8509fe2d3e2896e2f6dd23a362c0f17f153fadbeb6227b8ed4c6` | physical plausibility evidence |
| declared S4 input | 4,770 | `4005851e1ab22fd3a16ac17a8d5da3e051233f69f37419079f3553ad134ecfcf` | immutable reference input |
| declared S4 displacement CSV | 5,592 | `c81d94e0b4a849f87aa0f79c83a79b94d5661ac79e44ed826919ab432c87746b` | immutable required reference quantity |
| deterministic comparison ledger | 94,349 | `8e8dea51b6f7c663bacc41fda6103a4596db26e02f1ead6069d458f51e0102e6` | `294` row decisions, `passed=true`, zero warnings |

## Acceptance Traceability

Evidence abbreviations: `PH` = Harness phase index; `BT` = Build/Test report; `RV` = Reference Verification report; `PE` = Physics Evaluation report. `shell-s4` means the sole declared read-only S4 comparison model. Every row below has priority `must` in the approved requirements baseline.

| requirement_id | acceptance criterion | test/phase evidence | reference/physics evidence | release disposition |
| --- | --- | --- | --- | --- |
| `001` | Exactly one supported static step; unsupported procedure or second step fails deterministically. | `InpDomainMapping.*Procedure*`; `Mitc4ShellCli.*`; PH Steps 1/12; BT | N/A | released |
| `002` | S4 and S4R map to one FESA MITC4 path without equivalence claim. | `InpDomainMapping.MapsS4AndS4rThroughOneMitc4Identity`; PH Steps 0/1/7; BT | S4R is intentionally non-reference | released |
| `003` | Source element type and internal formulation remain separate metadata. | `DomainModel.Mitc4ShellRecordsPreserveSourceAndInternalIdentity`; `Hdf5ResultsWriter.WritesExactShellMetadataAndModelIdentity`; BT | RV HDF5 projection audit | released |
| `004` | Four distinct ordered nodes and stable source element identity are enforced. | `InpDomainMapping.RejectsInvalidShellConnectivityOptionsAndMixedModels`; Domain/HDF5 tests; BT | RV observed 36 uniquely identified S4 elements | released |
| `005` | Six global DOFs use the exact order and equation ownership remains in DofManager. | `DofManager.BuildsShellScatterInSourceNodeAndComponentOrder`; HDF5 schema tests; PH Steps 0/6/11; BT | RV `[UX,UY,UZ,URX,URY,URZ]` projection | released |
| `006` | Valid homogeneous isotropic `E,nu` is accepted and invalid/unsupported material data fails. | `InpDomainMapping.RejectsInvalidShellAssignmentsAndProperties`; `Mitc4ShellConstitutive.*`; BT | PE material audit | released |
| `007` | One finite positive constant thickness is accepted for a centered single-layer shell section. | Domain/model/mapping tests; `Mitc4ShellConstitutive.*`; BT | PE thickness/model audit | released |
| `008` | Each element resolves to exactly one section and material; missing/conflicting/duplicate assignments fail. | `DomainModel.ShellOwnershipPreservesResolvedAssignmentsAndOptionalFrames`; `InpDomainMapping.RejectsInvalidShellAssignmentsAndProperties`; BT | N/A | released |
| `009` | Multiple valid sets/sections/materials are allowed while each element remains homogeneous and single-layer. | Domain/model/mapping suites; PH Steps 0/1; BT | N/A | released |
| `010` | Composite, offset, variable thickness, explicit normal and orientation meanings fail closed. | `InpDomainMapping.RejectsInvalidShellConnectivityOptionsAndMixedModels`; BT | N/A | released |
| `011` | Nodal director is a unit vector separate from scalar thickness. | `Mitc4Geometry.BuildsDeterministicFramesForPlanarRotatedAndWarpedElements`; HDF5 director tests; BT | PE finite/model audit | released |
| `012` | Element normal candidate follows deterministic source order and tangent cross product. | `Mitc4Geometry.*`; PH Step 2; BT | N/A | released |
| `013` | Smooth shared-node directors use deterministic area-weighted averaging. | `Mitc4Geometry.AreaWeightsSharedDirectorsInStableSourceIdentityOrder`; BT | N/A | released |
| `014` | Nonfinite/zero/opposed normals fail without an invented smooth-angle threshold. | `Mitc4Geometry.RejectsInvalidSurfaceJacobianAndIncidentOrientationCases`; BT | N/A | released |
| `015` | Discontinuous shared-node director fields are not silently averaged; folds require duplicate nodes. | Geometry negative tests and mapper unsupported-scope tests; BT | Documented limitation | released |
| `016` | Duplicate, bow-tie, nonfinite, zero-area and nonpositive-J geometry fails at every required point. | `Mitc4Geometry.RejectsInvalidSurfaceJacobianAndIncidentOrientationCases`; `.ExposesTheCompleteRequiredValidationPointInventory`; BT | PE finite-result audit | released |
| `017` | Nodal label/set boundary targets support global DOFs 1-6 and zero/nonzero prescribed values. | `EssentialConstraints.PreservesShellSizedNoMixedAndAllConstraintRoundTrips`; `Mitc4ShellCli.AppliesKfcForNonzeroPrescribedDisplacement`; BT | PE constraint-mask audit | released |
| `018` | Global nodal force/moment CLOAD components aggregate deterministically. | `LoadAssembly.AggregatesAllSixGlobalShellLoadComponentsInSourceOrder`; BT | PE load/reaction audit | released |
| `019` | Aggregate director-parallel moment fails as `unsupported-drilling-load`. | `LoadAssembly.AcceptsExactlyZeroAggregateShellMoment`; `.EnforcesAggregateShellMomentDirectorProjectionThreshold`; PH Step 8; BT | N/A | released |
| `020` | Distributed/follower/body/edge load inputs remain unsupported. | `InpDomainMapping.PreservesProcedureLoadAndOutputRequestBoundariesForShells`; BT | Documented limitation | released |
| `021` | Only the approved identity-preserving keyword subset plus S4/S4R and shell section is accepted. | `InpDomainMapping.*`; full CTest regression; BT | `shell-s4` parsed end-to-end | released |
| `022` | Identity wrappers/multiple instances preserve source identity; transforms/nesting remain unsupported. | `InpDomainMapping.*`; Domain identity tests; BT | RV exact instance/node identity | released |
| `023` | Allowlisted output requests do not affect mandatory results; other model-affecting meanings fail. | `InpDomainMapping.PreservesProcedureLoadAndOutputRequestBoundariesForShells`; `Hdf5ResultsWriter.WritesShellInventoryDespiteRequestsAndOmitsForbiddenPaths`; BT | PE observed warning-only diagnostics | released |
| `024` | Domain owns shell semantics and AnalysisModel remains a non-owning active view. | `DomainModel.*`; PH Step 0 and full lifecycle Step 12; BT | N/A | released |
| `025` | DofManager solely owns six-DOF numbering, maps, scatter and sparse pattern. | `DofManager.*`; `EssentialConstraints.*`; PH Step 6; BT | N/A | released |
| `026` | AnalysisState owns only required linear-static shell solution/recovery/evidence rows. | `AnalysisState.OwnsExactShellRowsInStableElementAndLocationOrder`; `.CommitsFiniteShellGlobalEvidence`; BT | PE required-result audit | released |
| `027` | Element buffers and stable COO/fixed reduction are deterministic across thread paths. | `SparseAssembly.ShellSerialTbbReverseAndRepeatedRunsAreByteIdentical`; PH Step 7; BT | N/A | released |
| `028` | Stiffness/partition/factorization precedes load/effective RHS/substitution/recovery/commit. | `Mitc4ShellCli.UsesExistingLifecycleAndExactlyOneFactorization`; `.AppliesKfcForNonzeroPrescribedDisplacement`; `.DoesNotWriteAnInvalidRecoveryCandidate`; BT | PE final-state evidence | released |
| `029` | Reaction/free equilibrium derives from full residual `K*d-F`. | `ResultRecovery.KeepsFullResidualAndComputesGlobalShellEquilibrium`; BT | PE reaction and equilibrium reconstruction | released |
| `030` | S4/S4R use the same numerical path and may differ only in source metadata. | Mapper identity test; `SparseAssembly.S4AndS4rSemanticFixturesAssembleIdenticalStiffness`; HDF5 metadata tests; BT | S4R reference intentionally N/A | released |
| `031` | Physical kernel uses three translations plus two tangent rotations; drilling is not physical strain. | `Mitc4ShellKinematics.BuildsRightHandedFramesAndSeparatePhysicalDrillingMaps`; drill/recovery tests; BT | PE no drilling leakage | released |
| `032` | Deterministic right-handed frames transform global rotations to tangent/drilling coordinates. | `Mitc4ShellKinematics.BuildsRightHandedFramesAndSeparatePhysicalDrillingMaps`; `Mitc4Geometry.*`; BT | PE symmetry/direction evidence | released |
| `033` | Drilling is a symmetric positive numerical stabilization only. | `Mitc4ShellDrilling.*`; `Mitc4ShellKernel.*`; BT | PE physical-energy audit | released |
| `034` | `R+`, `k_ref`, `k_d=1e-3*k_ref`, and `I4` use only eight positive physical rotational diagonals. | `Mitc4ShellDrilling.UsesOnlyEightPositivePhysicalRotationDiagonalsAndFixedFactor`; BT | N/A | released |
| `035` | Drilling contributes to no physical generalized strain/resultant/stress/output. | `Mitc4ShellDrilling.ExcludesPureDrillFromPhysicalRecoveryAndEnergy`; HDF5 forbidden-path test; BT | PE physical-only recovery/energy | released |
| `036` | Empty/nonfinite valid `R+` fails; no coefficient/energy calibration gate or output exists. | `Mitc4ShellDrilling.FailsNonfiniteReferenceAndStabilizesEachPureDrillCoordinate`; BT | Documented limitation/boundary | released |
| `037` | S4 and S4R share the approved full `2x2x2` rule; no reduced integration/hourglass selection. | `Mitc4ShellKinematics.UsesOneFixedTwoByTwoByTwoQuadratureOrder`; S4/S4R assembly parity; BT | RV S4-only boundary | released |
| `038` | Stabilized element keeps six physical rigid modes, symmetry, energy invariance and positive non-rigid modes. | `Mitc4ShellKernel.*`; `Mitc4ShellPatch.*`; BT | PE rigid/rank/energy evidence | released |
| `039` | HDF5 is authoritative and invalid candidates cannot replace a valid final result. | `Hdf5ResultsWriter.InvalidShellInventoryPreservesExistingFinal`; CLI invalid-candidate test; BT | RV/PE read authoritative HDF5 | released |
| `040` | Required metadata/model identities, frames, directors, section/material and source/internal types are written. | `Hdf5ResultsWriter.WritesExactShellMetadataAndModelIdentity`; BT | RV HDF5 schema audit | released |
| `041` | Every node has global six-component displacement and full-residual reaction rows in stable order. | HDF5 mandatory inventory; `ResultRecovery.*`; BT | RV 49x6 displacement; PE reaction audit | released |
| `042` | Four shell locations contain ordered eight-component generalized strain with correct dimensions. | `Mitc4ShellPhysicalRecovery.*`; `ResultRecovery.RecoversShellRowsInStableElementAndGpOrder`; HDF5 tests; BT | PE 144-GP reconstruction | released |
| `043` | The same locations contain ordered `N/M/Q` section resultants with correct dimensions. | Physical recovery/result recovery/HDF5 suites; BT | PE 1,152-component resultant reconstruction | released |
| `044` | Bottom/middle/top local `[S11,S22,S12]` is emitted; S33/S13/S23 is not. | `ResultRecovery.RecoversDirectBottomMiddleTopShellStress`; HDF5 inventory/forbidden paths; BT | PE stress/location/sign reconstruction | released |
| `045` | Rows preserve source element, exact natural/section location, frame and component order without averaging. | AnalysisState, ResultRecovery stable-order and HDF5 schema tests; BT | PE location-specific audit | released |
| `046` | Free residual, force/moment balance and deterministic physical shell energy are output without drilling datasets. | `ResultRecovery.*ShellEquilibrium`; `.SumsOnlyPhysicalShellEnergyInSourceOrder`; HDF5 global rows; BT | PE equilibrium and energy checks | released |
| `047` | Abaqus output requests neither suppress nor expand mandatory HDF5; CSV remains auxiliary. | Mapper output-request test; `Hdf5ResultsWriter.WritesShellInventoryDespiteRequestsAndOmitsForbiddenPaths`; BT | RV compared HDF5 directly; no FESA CSV | released |
| `048` | Nonfinite/incomplete recovery or HDF5 inventory fails without partial success. | `AnalysisState.InvalidShellCandidatesLeavePriorStateUnchanged`; `ResultRecovery.InvalidLaterShellLeavesEntirePriorStateUnchanged`; HDF5 invalid-inventory test; BT | N/A | released |
| `049` | Each production behavior has RED/GREEN/VERIFY evidence, related C++ tests, clean MSVC Debug build and no new warning. | PH Steps 0-13 and outputs; BT clean build, zero warnings, `144/144` | N/A | released |
| `050` | Frames, Jacobians, symmetry, transform energy, six modes, positivity and repeatability are tested. | Geometry, Kinematics, Kernel, Patch and SparseAssembly suites; BT | PE rigid/rank summary | released |
| `051` | Approved normalized `1e-12` and `1e-10` algebraic/equilibrium criteria are applied. | Kernel/frame tests; `ResultRecovery.UsesScaleAwareShellMetricsAndRejectsExcess`; BT | PE verification metrics all below `1e-10` | released |
| `052` | Independent membrane, bending, shear and twist patch/sign/component checks pass. | `Mitc4ShellPatch.ReproducesIndependentMembraneBendingShearAndTwistFields`; PhysicalRecovery tests; BT | PE recovery sign checks | released |
| `053` | Formulation invariants/patches and declared S4 displacement reference case pass; expanded portfolio is not required. | Kernel/Patch/PhysicalRecovery suites; `Mitc4S4Reference.*`; BT | RV blocking U `147/147`; PE coverage audit | released |
| `054` | Exact geometry acceptance/rejection tests pass without NR-O03/NR-O04 calibration. | `Mitc4Geometry.*`; BT | N/A | released |
| `055` | Additional curved/locking/convergence benchmarks remain optional and nonblocking. | Implementation-plan scope audit; BT/PE coverage inventory | PE records limitation and approved coverage | released |
| `056` | Exact drilling formula, symmetry/positivity/rank/determinism and recovery exclusion are verified. | `Mitc4ShellDrilling.*`; Kernel/Sparse/Recovery suites; BT | PE drilling separation evidence | released |
| `057` | Physics verifies equilibrium, direction, symmetry, energy, signs and resultant consistency. | ResultRecovery/CLI suites; BT | PE all documented checks pass | released |
| `058` | Every matched U row uses fixed absolute `1.0e-5` and blocks on exceedance. | `Mitc4ReferenceComparison.AppliesFixedAbsoluteToleranceWithoutScaleClampOrRowDenominator`; `Mitc4S4Reference.*`; BT | RV U `147/147` pass | released |
| `059` | Reference scale, row denominator, component magnitude and zero clamp never alter MITC4 tolerance. | Fixed-tolerance comparator test; BT | RV all 294 tolerances exactly `1.0e-5` | released |
| `060` | U tolerance is in user-consistent length units and independent of B33 policy. | Comparator contract test and scope audit; BT | RV reports independent fixed policy | released |
| `061` | UR uses fixed absolute `1.0e-5`; exceedance warns deterministically and never blocks. | `Mitc4ReferenceComparison.RotationExceedanceWarnsWithoutBlockingTranslationVerdict`; BT | RV UR `147/147`, zero warnings | released |
| `062` | UR tolerance is dimensionless and no extra UR/drilling threshold is required. | Comparator/report tests; BT | RV fixed-tolerance metrics | released |
| `063` | Missing/extra/duplicate/nonfinite/schema/identity mismatch fails before tolerance. | `Mitc4ReferenceComparison.RejectsInvalidInventoryBeforeNumericComparison`; BT | RV all invalid counts zero | released |
| `064` | Report contains every U/UR decision, maximum, normalized, RMS, vector and worst-row evidence. | `Mitc4ReferenceComparison.ReportsMetricsVectorsWorstRowAndJsonDeterministically`; BT | RV complete quantity/component/worst-row tables | released |
| `065` | Exact S4 input and displacement CSV paths are used without mutation. | `Mitc4S4Reference.*`; comparator required-file test; BT hash audit | `shell-s4`; immutable hashes match | released |
| `066` | S4R artifacts are not required/consumed; parser/common-kernel/assembly/HDF5 tests cover S4R. | Mapper identity, S4/S4R assembly parity, HDF5 source-type tests; BT | RV confirms `reference/shellR/` not consumed | released |
| `067` | Only declared input/CSV, FESA HDF5, mapping and tolerance/precheck rules gate readiness. | `Mitc4ReferenceComparison.RequiresOnlyDeclaredInputCsvAndHdf5`; BT | RV no administrative artifact gate | released |
| `068` | Reference rows are unique, finite and deterministically source-mapped without internal-equivalence inference. | Comparator mapping and invalid-inventory tests; BT | RV exact `294/294` key set | released |
| `069` | Sole Abaqus case is full-integration S4; S4R coverage remains non-reference. | Common quadrature/S4R mapping tests and `Mitc4S4Reference.*`; BT | RV one declared case, S4R excluded | released |
| `070` | Authoritative FESA HDF5 rows are compared directly by model/step/frame/source/component. | Comparator mapping/E2E tests; BT | RV direct HDF5 projection, no FESA CSV | released |
| `071` | Reaction/stress/strain/resultants do not become undeclared equality gates. | Comparator only projects U/UR; BT | RV and PE keep optional CSVs out of pass/fail | released |
| `072` | No Abaqus/reference-solver execution or reference artifact mutation occurs. | PH/BT Git and hash audits | RV and PE no-change assertions; immutable hashes match | released |

No requirement is deferred or blocked. Out-of-scope behavior is documented as a limitation rather than silently accepted.

## Validation Evidence

| command or report | expected | observed | verdict |
| --- | --- | --- | --- |
| config-resolved VS18/MSVC x64 Debug fresh configure and clean build | exit `0`, no new warning | exit `0`; warning/error scan `0/0` | pass |
| focused model/kernel/assembly/recovery CTest | pass | `87/87` | pass |
| focused linear-static lifecycle CTest | pass | `10/10` | pass |
| focused MITC4 reference CTest | pass | `8/8` | pass |
| CTest discovery and full regression | nonzero inventory and all pass | `144` discovered; `144/144` pass; current read-only discovery includes 57 test names containing `Mitc4` or `Shell` | pass |
| Harness Python verification | pass because Harness runner changed on the feature branch | `7/7` pass | pass |
| final release-stage confirmation | current HEAD build, full CTest and Harness self-test pass | fresh `cmake --build` exit `0`; CTest `144/144`; Harness pytest `7/7` | pass |
| Harness implementation ledger | every Step completed successfully | Steps `0-13` completed; `14/14` output `exitCode=0` | pass |
| reference verification | `pass-for-physics-evaluation` | exact 294 rows; U `147/147`; invalid rows/warnings `0` | pass |
| physics evaluation | `pass-for-release-agent` | all equilibrium/direction/symmetry/recovery/energy checks pass | pass |
| immutable reference audit | exact expected hashes, no Git reference diff/status | both hashes match; zero changed reference paths | pass |

The Release Agent did not run Abaqus. It independently read the complete upstream evidence chain, enumerated current CTest discovery read-only, checked all Harness output exit codes, verified source HEAD/branch/status, and recomputed the declared artifact/report hashes. The primary audit then performed a fresh current-HEAD incremental full build, full CTest run and Harness self-test as the final completion check; all passed as recorded above.

## Release Checklist

- [x] One `feature_id` across all required gate documents.
- [x] Requirements, research, formulation, numerical review, I/O, reference-model and implementation-plan gates are approved/passing for their intended downstream phase.
- [x] Harness implementation is complete at the audited source HEAD with 14 successful Step outputs.
- [x] Independent Build/Test status is `pass-for-reference-verification`.
- [x] Reference Verification status is `pass-for-physics-evaluation`.
- [x] Physics Evaluation status is `pass-for-release-agent`.
- [x] All `must` requirements `001-072` trace to acceptance criteria, test/phase evidence, reference/physics evidence where applicable, and a released disposition.
- [x] Sole required comparison files exist, match approved hashes, and were not modified.
- [x] Fixed MITC4 tolerance and U-blocking/UR-warning-only policy are unchanged.
- [x] No unresolved build, test, reference, physics, schema, identity, nonfinite or environment failure remains.
- [x] Known limitations, unsupported Abaqus meanings and accepted risks are documented below and in the Release Notes Draft.
- [x] Release Agent changed only this report and performed no external release action.

## Known Limitations

| limitation | category | user impact | disposition |
| --- | --- | --- | --- |
| One small-displacement/small-rotation linear-static step only | analysis | Nonlinear, buckling, modal, dynamic, contact and thermal models are rejected/not executed. | documented |
| S4 and S4R are source labels for one full-integration FESA-MITC4 formulation | input/numerical | No Abaqus S4/S4R internal algorithm, reduced-integration or hourglass equivalence is claimed. | documented |
| External acceptance uses one flat symmetric fully clamped S4 plate | verification | General curved/distorted/thin-thick convergence is not established by the source-solver comparison. | accepted risk; optional future evidence |
| Original MITC4 membrane field is unmodified | numerical | Distorted curved meshes may exhibit membrane locking; MITC4+ performance is not claimed. | documented |
| S4R has no blocking Abaqus reference comparison | verification | S4R support is proven by parser/common-kernel/deterministic-assembly/HDF5 metadata tests only. | approved boundary |
| Homogeneous isotropic centered single layer with constant thickness | material/section | Composite, orthotropic, offset and variable-thickness models are unsupported. | documented |
| Smooth geometry-derived director field only | geometry | Explicit normals and shared-node folds/hinges/intersections are unsupported; folds require duplicated nodes. | documented |
| Nodal loads/constraints only | load | Pressure, gravity, DLOAD, body/edge/follower load are unsupported. Director-parallel moments fail as `unsupported-drilling-load`. | documented |
| Fixed numerical drilling stabilization | numerical | It is not a physical strain/load/result channel; no calibration sweep or drilling-energy ratio is supplied. | accepted fixed policy |
| In-plane stress only at bottom/middle/top | output | `S33` is a plane-stress assumption; `S13/S23` point stress and nodal averaging are not emitted. | documented |
| Raw HDF5 container bytes are not a declared deterministic identity | output/evidence | Regeneration may change the raw file hash; ordered projected rows and the JSON comparison ledger are deterministic evidence. | documented, nonblocking |
| Target-wide CTest label remains the legacy beam label | test infrastructure | MITC4 selection uses the approved exact suite regexes instead of a dedicated label. | documented, nonblocking |

## Release Notes Draft

### Feature Summary

- Adds end-to-end single-step linear-static analysis for four-node shell inputs labeled `S4` or `S4R`, both mapped to the independent full-integration `FESA-MITC4` formulation.
- Adds deterministic geometry-derived nodal directors, six global nodal DOFs, MITC4 transverse-shear tying, fixed nonphysical drilling stabilization, deterministic sparse assembly, full-residual reactions, physical shell recovery and failure-atomic HDF5 output.
- Adds mandatory HDF5 nodal displacement/reaction, shell local frames, generalized strain/resultant, bottom/middle/top in-plane stress, physical energy, equilibrium and verification metrics.

### Verification Scope

- Clean Visual Studio 18 2026/MSVC x64 Debug build and full `144/144` CTest regression passed with zero compiler/linker warnings.
- All 14 Harness implementation Steps completed with recorded RED/GREEN/VERIFY evidence and successful output exit codes.
- The sole declared S4 case matched all `147` blocking translational rows within fixed absolute `1.0e-5`; all `147` rotation rows were within the warning threshold and produced no warnings.
- Physics checks passed for global force/moment equilibrium, full-residual reactions, displacement direction, double symmetry, generalized resultant/stress consistency, free residual, finite results and positive physical energy.

### Main Limitations

- The released scope is linear static, small deformation, homogeneous isotropic single-layer MITC4 with nodal loads and constraints only.
- Abaqus compatibility and Abaqus S4/S4R formulation equivalence are not claimed. S4R uses the same FESA full-integration kernel and is not an Abaqus reference gate.
- Broader curved/distorted/thin-thick convergence, original-MITC4 membrane-locking characterization, nonlinear execution, distributed loads, composites, physical drilling behavior and expanded stress output remain outside this release.

### Artifacts

- Release report: `docs/releases/linear-static-mitc4-shell-release.md`
- Build/Test report: `docs/build-test-reports/linear-static-mitc4-shell-build-test.md`
- Reference Verification report: `docs/reference-verifications/linear-static-mitc4-shell-reference-verification.md`
- Physics Evaluation report: `docs/physics-evaluations/linear-static-mitc4-shell-physics-evaluation.md`
- Declared reference pair: `reference/shell/shell.inp`, `reference/shell/shell displacements.csv`
- Build-local deterministic ledger: `.harness/build/reference/mitc4-shell-s4-comparison/comparison.json`

## Release Verdict

- verdict: `ready-for-release`
- reason: all required upstream gates are present and passing; the final three mandatory handoff statuses are exactly `pass-for-reference-verification`, `pass-for-physics-evaluation`, and `pass-for-release-agent`; every `must` requirement `001-072` has a released disposition; required S4 artifacts and row mappings are present and valid; no unresolved defect, missing comparison file, tolerance conflict, nonfinite result, identity gap, or physics blocker remains.
- approval_scope: internal feature release closure only
- external_release_action: `none`

## Handoff Recommendation

| target_agent | reason | required_input |
| --- | --- | --- |
| Coordinator Agent | Close the feature workflow with `ready-for-release`. | This report, source HEAD `820ba30c717b3d0e113775608e20dfd5fbc05d53`, and the three passing downstream gate reports. |
| Correction Agent | N/A; no implementation-owned release blocker remains. | N/A |
| Reference Verification Agent | N/A; the required S4 comparison is complete and passing. | N/A |
| Physics Evaluation Agent | N/A; physics evaluation is complete and passing. | N/A |

## No-Change Assertion

- source_files_modified: `false`
- test_files_modified: `false`
- cmake_files_modified: `false`
- requirements_modified: `false`
- research_modified: `false`
- formulation_modified: `false`
- numerical_review_modified: `false`
- io_contract_modified: `false`
- reference_model_contract_modified: `false`
- implementation_plan_or_phase_files_modified: `false`
- build_test_report_modified: `false`
- reference_verification_report_modified: `false`
- physics_evaluation_report_modified: `false`
- reference_artifacts_modified: `false`
- tolerance_policies_modified: `false`
- Abaqus_or_other_reference_solver_executed: `false`
- publish_deploy_package_tag_commit_performed: `false`
- owned_report_created: `true`
- pre_existing_untracked_reports_preserved: `true`
- notes: before this report was created, the worktree had no tracked/staged diff and contained only the three upstream gate reports as untracked files. This audit adds only `docs/releases/linear-static-mitc4-shell-release.md`; generated build-local evidence remains ignored under `.harness/build/`.

## Open Issues

- blocking: `none`
- deferred requirements: `none`
- unresolved defects: `none`
- missing required comparison files or mappings: `none`
- nonblocking administrative note: the Build/Test, Reference Verification, Physics Evaluation and this Release report are untracked workspace reports pending whatever repository-integration action the user or Coordinator Agent separately authorizes. Their untracked state does not invalidate their content or the current internal readiness verdict.
- nonblocking evidence note: raw `results.h5` hashes can differ across valid regenerations; no byte-identical HDF5 container claim is made.
