FESADev/phases/1-linear-static-mitc4/step2.md

Step 2: domain-model

Sprint Contract

Objective

Implement immutable-ish Domain entities for Phase 1 input data: nodes, elements, sets, materials, shell sections, loads, boundaries, and steps.

Required Reading

• /AGENTS.md
• /PROGRESS.md
• /PLAN.md
• /docs/README.md
• /docs/HARNESS_ENGINEERING.md
• /docs/PRD.md
• /docs/ARCHITECTURE.md
• /docs/ADR.md
• /docs/NUMERICAL_CONVENTIONS.md
• /docs/ABAQUS_INPUT_SUBSET.md
• /phases/1-linear-static-mitc4/step1.md

Scope

• Add Domain-level value objects and containers preserving input ids and labels.
• Support Phase 1 shell elements as Abaqus TYPE=S4 mapped to FESA MITC4.
• Represent node sets, element sets, linear elastic materials, shell sections, fixed boundary conditions, nodal loads, and linear static steps.
• Provide lookup APIs and duplicate-id diagnostics without storing equation ids in entities.

Allowed Files

• include/**
• src/**
• tests/**
• PLAN.md
• PROGRESS.md
• phases/1-linear-static-mitc4/index.json

Explicit Non-Goals

• Do not parse Abaqus files in this step.
• Do not create AnalysisModel, AnalysisState, or DofManager.
• Do not add support for S4R, pressure loads, nonzero prescribed displacement, Part/Assembly/Instance, dynamics, nonlinear steps, or thermal coupling.

Tests To Write First

• Domain construction tests for nodes, elements, sets, materials, shell sections, loads, boundaries, and steps.
• Duplicate id/name tests with diagnostics.
• Lookup tests proving labels and ids are preserved.

Reference Artifacts

• None.

Acceptance Commands

python scripts/validate_workspace.py

Evaluator Checklist

• Domain preserves model definition and is treated as immutable after construction.
• Node and element objects do not own global equation numbers.
• Phase 1 object set matches docs/ABAQUS_INPUT_SUBSET.md.
• Tests cover duplicate and missing lookup behavior.

Handoff Requirements

• Record changed files and validation in PROGRESS.md.
• Update future tasks in PLAN.md only if Domain scope changes.
• Update the matching phase index entry: use completed with a one-line summary, or blocked with blocked_reason, or error with error_message.

Verification

1. Run the acceptance command.
2. Inspect Domain APIs for architecture-boundary drift.

Do Not

• Do not make Domain depend on solver adapters, analysis strategies, or result writers.