# 3D Euler-Bernoulli Beam Kernel Release Readiness Note

## Metadata
- feature_id: euler-beam-3d
- source_requirement: docs/requirements/euler-beam-3d.md
- source_formulation: docs/formulations/euler-beam-3d-formulation.md
- source_numerical_review: docs/numerical-reviews/euler-beam-3d-review.md
- source_io_definition: docs/io-definitions/euler-beam-3d-io.md
- source_reference_model: docs/reference-models/euler-beam-3d-reference-models.md
- source_implementation_plan: docs/implementation-plans/euler-beam-3d-implementation-plan.md
- source_build_test_report: docs/build-test-reports/euler-beam-3d-build-test.md
- source_reference_verification_report: N/A
- source_physics_evaluation_report: N/A
- status: not-release-ready-kernel-increment-complete
- owner_agent: release-agent
- date: 2026-06-12

## Release Scope

| item | included | excluded | notes |
| --- | --- | --- | --- |
| analysis_type | element kernel calculations | full linear static solve | Solver integration is not complete. |
| element_type | two-node straight prismatic 3D Euler-Bernoulli beam kernel | Timoshenko beams, curved beams, offsets, releases, warping | Kernel scope only. |
| material_model | positive finite `E` and `G` constants supplied to the kernel | material parser or library integration | No material database integration. |
| section_model | positive finite `A`, `J`, `Iy`, `Iz` constants supplied to the kernel | beam section parser/property integration | Future I/O phase required. |
| output_quantities | local/global stiffness and local/global end forces returned in memory | HDF5 results, reference CSV views, stress recovery | Authoritative output path is future work. |

## Completed Kernel Increment
- Added semantic `ElementTopology::beam2`.
- Added local 12x12 Euler-Bernoulli beam stiffness for axial, torsion, and two bending planes.
- Added local end-force recovery as `K_local * u_local`.
- Added local axis construction from two nodes plus an orientation vector.
- Added global stiffness transformation using `K_global = T^T K_local T`.
- Added global end-force recovery using the same transformation convention.
- Added unit tests for topology, local stiffness entries, local symmetry, local force recovery, invalid local inputs, identity transform, rotated symmetry, rigid translation, axial extension, parallel orientation, and zero orientation.

## Missing For Full Feature Release
- Parser implementation for the approved Abaqus subset.
- Beam section/property semantic model integration.
- Material-to-section mapping for `E`, `G`, `A`, `J`, `Iy`, and `Iz`.
- Assembler and static solver integration.
- HDF5 result emission for beam displacement, reaction, and internal force quantities.
- Stored Abaqus reference artifacts under `reference/<model-id>/`.
- Reference comparison report.
- Physics sanity report.
- Final release report with all upstream gates passing.

## Gate Evidence Inventory

| gate | source | expected_status | observed_status | verdict |
| --- | --- | --- | --- | --- |
| requirements | docs/requirements/euler-beam-3d.md | sufficient for kernel | draft with explicit kernel scope | pass for kernel |
| research | docs/research/euler-beam-3d-research.md | ready-for-formulation | ready-for-formulation | pass |
| formulation | docs/formulations/euler-beam-3d-formulation.md | ready-for-numerical-review | ready-for-numerical-review | pass |
| numerical_review | docs/numerical-reviews/euler-beam-3d-review.md | pass-for-implementation-planning | pass-for-implementation-planning | pass |
| io_definition | docs/io-definitions/euler-beam-3d-io.md | future integration contract | ready-for-implementation-planning | pass for planning |
| reference_model | docs/reference-models/euler-beam-3d-reference-models.md | artifacts present for release | needs-reference-artifacts | fail for release |
| implementation | source and tests | implemented kernel | implemented kernel | pass for kernel |
| build_test | docs/build-test-reports/euler-beam-3d-build-test.md | pass | pass-for-reference-verification | pass |
| reference_verification | docs/reference-verifications/euler-beam-3d-reference-verification.md | pass-for-physics-evaluation | missing | fail for release |
| physics_evaluation | docs/physics-evaluations/euler-beam-3d-physics-evaluation.md | pass-for-release-agent | missing | fail for release |

## Acceptance Traceability

| requirement_id | release_disposition |
| --- | --- |
| EB3D-REQ-001 through EB3D-REQ-011 | Implemented and unit-tested at kernel level. Full solver evidence deferred. |
| EB3D-REQ-012 | Excluded behaviors remain out of scope. |
| EB3D-REQ-013 | No reference artifacts were created or modified. |
| EB3D-REQ-014 | No full Abaqus compatibility claim is made. |
| EB3D-REQ-015 | Kernel completion is explicitly separate from full solver release readiness. |

## Validation Evidence

| command_or_report | expected | observed | notes |
| --- | --- | --- | --- |
| `ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R "model_element_test\|euler_beam_3d_(local_stiffness\|transform_recovery)_test"` | pass | pass, 3/3 tests | Feature-specific CTest filter passed. |
| `python -m unittest discover -s scripts -p "test_*.py"` | pass | pass, 104 tests | Harness self-test passed. |
| `python scripts/validate_workspace.py` | pass | pass, 23/23 CTests | Used absolute CMake/CTest commands through `HARNESS_VALIDATION_COMMANDS`. |

## Known Limitations

| limitation | category | user_impact | disposition |
| --- | --- | --- | --- |
| No parser support for beam input yet. | input | Users cannot run beam `.inp` models end-to-end. | deferred |
| No section/property model integration. | model | Constants must be supplied directly to the kernel API. | deferred |
| No assembly/static solver integration. | solver | Beam elements do not contribute to a global system yet. | deferred |
| No HDF5 result output for beam quantities. | output | No official solver output exists for beam results. | deferred |
| No reference artifacts or comparison report. | verification | Full solver correctness against Abaqus is not established. | blocker for release |
| No stress or strain recovery. | physics/output | Stress CSV and stress HDF5 datasets are not available. | deferred |
| No shear deformation, warping, releases, offsets, mass, geometric stiffness, nonlinear, dynamic, or thermal behavior. | physics | Feature is limited to the approved Euler-Bernoulli kernel. | documented |

## Release Notes Draft

### Feature Summary
- Kernel increment for a two-node 3D Euler-Bernoulli beam element is complete.

### Verification Scope
- Unit-tested local stiffness, local end forces, global transform, global end forces, and invalid geometry/section handling.

### Main Limitations
- This is not an end-to-end solver feature. Parser, assembly, HDF5 output, reference comparison, and physics sanity remain future gates.

### Artifacts
- docs/build-test-reports/euler-beam-3d-build-test.md
- docs/requirements/euler-beam-3d.md
- docs/formulations/euler-beam-3d-formulation.md
- docs/reference-models/euler-beam-3d-reference-models.md

## Release Verdict
- verdict: not-release-ready-kernel-increment-complete
- reason: kernel implementation and build/test validation are complete, but full feature release lacks parser integration, HDF5 output, reference artifacts, reference verification, and physics sanity evidence.

## Handoff Recommendation

| target_agent | reason | required_input |
| --- | --- | --- |
| Coordinator Agent | Decide next phase sequencing. | This release note and phase index. |
| I/O Definition Agent | Finalize exact Abaqus beam subset and section/orientation keywords. | Current I/O contract and kernel API behavior. |
| Reference Model Agent | Generate approved future reference artifact contracts and then artifacts in an explicit phase. | Reference model contract. |
| Implementation Agent | Integrate kernel into parser/model/assembly only after upstream contracts are approved. | Implementation plan and build/test report. |

## No-Change Assertion
- source_files_modified: false in this release note step.
- test_files_modified: false in this release note step.
- cmake_files_modified: false.
- reference_artifacts_modified: false.
- tolerance_policies_modified: false.

## Open Issues
- Full solver release remains blocked until the missing gates listed above are completed.