FESADev/phases/euler-beam-3d/step5.md

Step 5: implementation-plan

Read These Files First

Read the following files before editing:

• /AGENTS.md
• /docs/PRD.md
• /docs/ARCHITECTURE.md
• /docs/ADR.md
• /docs/SOLVER_AGENT_DESIGN.md
• /docs/implementation-plans/README.md
• /docs/requirements/euler-beam-3d.md
• /docs/research/euler-beam-3d-research.md
• /docs/formulations/euler-beam-3d-formulation.md
• /docs/numerical-reviews/euler-beam-3d-review.md
• /docs/io-definitions/euler-beam-3d-io.md
• /docs/reference-models/euler-beam-3d-reference-models.md
• /src/fesa/model/element.hpp
• /tests/unit/model_element_test.cpp

Task

Create /docs/implementation-plans/euler-beam-3d-implementation-plan.md.

The implementation plan must be ready for C++ TDD work and must include:

• readiness check for requirements, research, formulation, numerical review, I/O, reference model contract
• explicit kernel-first implementation scope
• tasks matching the remaining phase steps:
  • model beam topology
  • local stiffness kernel
  • global transform and end-force recovery
  • build/test report
  • release readiness note
• test IDs and RED/GREEN conditions for each production change
• candidate files:
  • src/fesa/model/element.hpp
  • src/fesa/model/element.cpp
  • tests/unit/model_element_test.cpp
  • src/fesa/elements/euler_beam_3d.hpp
  • src/fesa/elements/euler_beam_3d.cpp
  • tests/unit/euler_beam_3d_local_stiffness_test.cpp
  • tests/unit/euler_beam_3d_transform_recovery_test.cpp
• CTest commands:
  • ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R model_element_test
  • ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R euler_beam_3d_local_stiffness_test
  • ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R euler_beam_3d_transform_recovery_test
• acceptance traceability from requirements to tests

Do not create C++ files in this step.

Tests To Write First

• No C++ test is required in this documentation-only step.

Acceptance Criteria

python -m unittest discover -s scripts -p "test_*.py"
python scripts/validate_workspace.py

Verification Notes

1. Confirm every production file named in the plan has a related test.
2. Confirm the plan does not ask Implementation Agent to change requirements, formulation, I/O contracts, reference artifacts, or tolerance policies.
3. Update phases/euler-beam-3d/index.json step 5:
   • success: "status": "completed", "summary": "3D Euler beam implementation plan added"
   • failure after retries: "status": "error", "error_message": "<specific error>"
   • blocked: "status": "blocked", "blocked_reason": "<specific reason>"

Forbidden

• Do not modify source, tests, reference artifacts, or CMake files.