FESADev/phases/1-linear-static-mitc4/step8.md

Step 8: results-writer-minimal

Sprint Contract

Objective

Implement the minimal result model and writer boundary for Phase 1 U and RF step/frame/field outputs.

Required Reading

• /AGENTS.md
• /PROGRESS.md
• /PLAN.md
• /docs/README.md
• /docs/HARNESS_ENGINEERING.md
• /docs/ARCHITECTURE.md
• /docs/ADR.md
• /docs/NUMERICAL_CONVENTIONS.md
• /docs/RESULTS_SCHEMA.md
• /phases/1-linear-static-mitc4/step6.md
• /phases/1-linear-static-mitc4/step7.md

Scope

• Add result data structures for model ids/connectivity plus step/frame/field outputs.
• Support mandatory Phase 1 fields U and RF with components UX, UY, UZ, RX, RY, RZ.
• Add an in-memory or file-backed writer boundary as appropriate for the current build system.
• If HDF5 is implemented now, keep HDF5 APIs behind an adapter/wrapper.

Allowed Files

• include/**
• src/**
• tests/**
• docs/RESULTS_SCHEMA.md only for clarification of agreed schema details
• PLAN.md
• PROGRESS.md
• phases/1-linear-static-mitc4/index.json

Explicit Non-Goals

• Do not add stress, strain, shell force, history, nonlinear frame, thermal, or composite outputs unless R-007 is resolved and docs are updated first.
• Do not write RF from reduced vectors only.
• Do not expose HDF5 APIs in solver core headers.

Tests To Write First

• Schema tests for step/frame layout and mandatory field names.
• Component-label and ordering tests for U and RF.
• Model id/connectivity storage tests using int64 ids.
• Adapter-boundary tests if HDF5 is introduced.

Reference Artifacts

• None for solver regression. This step only prepares output data consumed by later comparison.

Acceptance Commands

python scripts/validate_workspace.py

Evaluator Checklist

• Result layout follows docs/RESULTS_SCHEMA.md.
• U and RF have six components in the documented order.
• HDF5, if present, is isolated behind an adapter.
• No extra Phase 1 outputs were added without resolving R-007.

Handoff Requirements

• Record result writer scope and validation in PROGRESS.md.
• Update PLAN.md if R-007 changes or output scope remains blocked.
• 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 tests for schema and component ordering.

Do Not

• Do not treat a file being created as proof that its schema matches the contract.