FESADev/phases/analysis-model-objects/step2.md

Step 2: element-base-interface

Read First

Read these files before editing:

• /AGENTS.md
• /docs/AGENT_RULES.md
• /docs/ARCHITECTURE.md
• /docs/implementation-plans/analysis-model-objects-implementation-plan.md
• /include/fesa/core/ElementDefinition.hpp
• /CMakeLists.txt

Task

Add the abstract element model interface.

Allowed files:

• Create /include/fesa/element/Element.hpp
• Create /tests/element/element_base_test.cpp
• Modify /tests/core/domain_bootstrap_test.cpp only if the current test executable remains the single test runner
• Modify /CMakeLists.txt

Required interface:

• virtual destructor.
• ElementId id() const noexcept.
• ElementType type() const noexcept.
• std::size_t nodeCount() const noexcept.
• std::span is not allowed because this project targets C++17.
• Use const reference return for connectivity data.
• no stiffness, residual, stress, state, or equation API in this phase.

Tests To Write First

Write /tests/element/element_base_test.cpp before production changes. Use a small test subclass to prove:

• base pointer dispatch works.
• id/type/connectivity/property id are readable through base API.
• deleting through std::unique_ptr<Element> is valid.

Run targeted build and confirm RED because Element.hpp is missing.

Acceptance Criteria

Run:

python scripts/validate_workspace.py
ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R model-object

Update step 2 status.

Do Not

• Do not implement MITC4 stiffness or numerical element behavior.