FESADev/phases/domain-model-foundation/step3.md

Step 3: node-and-domain-storage

Read First

Read these files before editing:

• /AGENTS.md
• /docs/AGENT_RULES.md
• /docs/ADR.md
• /docs/ARCHITECTURE.md
• /docs/implementation-plans/domain-model-foundation-implementation-plan.md
• /include/fesa/core/ModelTypes.hpp
• /CMakeLists.txt

Task

Implement the first useful Node and Domain slice.

Allowed files:

• Create /include/fesa/core/Node.hpp
• Create /include/fesa/core/Domain.hpp
• Create /src/core/Domain.cpp
• Create or modify /tests/core/domain_storage_test.cpp
• Modify /CMakeLists.txt to compile the source and register the test

Required behavior:

• Node stores NodeId and three coordinates as double.
• Domain::addNode(Node) inserts a node.
• Duplicate node ids throw std::invalid_argument.
• Domain::findNode(NodeId) returns a pointer or nullptr.
• Domain::node(NodeId) returns a const reference or throws std::out_of_range.
• Domain::nodeCount() returns the stored node count.
• Domain must not expose mutable node references.

Tests To Write First

Write failing tests before creating production headers/sources:

• Add and retrieve one node by id.
• Missing node returns nullptr from findNode.
• Missing node throws from node.
• Duplicate node id throws.

Run the targeted CTest and verify failure due to missing API. Then implement the minimal code.

Acceptance Criteria

Run:

cmake --build build/msvc-debug --config Debug
ctest --test-dir build/msvc-debug --output-on-failure -C Debug -R domain
python scripts/validate_workspace.py

Update /phases/domain-model-foundation/index.json step 3 with completed, error, or blocked.

Do Not

• Do not add elements, materials, properties, sets, loads, or steps yet.
• Do not store equation ids, displacement vectors, residuals, reactions, or solver state.