fix: restore implementation comparison safeguards

.codex/skills/fesa-cpp-msvc-tdd/SKILL.md

@@ -70,7 +70,9 @@ test inventory, handoff recommendation, no-change assertion, and open issues.
 
 `reference-comparison.md` records the exact input/CSV artifact inventory, `results.h5`, HDF5
 projection, source-ID/component matching, row prechecks, approved tolerance, per-quantity
-results, classification, handoff, no-change assertion, and open issues.
+per-row decisions, max absolute error, max relative or component-normalized error, RMS error,
+norm error where the approved feature contract makes each metric applicable, classification,
+handoff, no-change assertion, and open issues.
 
 Required validation commands:
 
@@ -99,6 +101,9 @@ uv run --with pytest python -m pytest -v -rs
 - Do not change reference artifacts.
 - Do not change tolerance policies.
 - Do not change declared reference inputs.
+- Do not modify `docs/<feature-id>/reference-model.md` or its reference-model contracts/evidence,
+  including declared comparison quantities, source identity/component rules, artifact contracts,
+  or approved tolerance, to make comparisons pass.
 - Do not run Abaqus, Nastran, or any reference solver.
 - Do not generate or modify Abaqus reference CSV files.
 - Do not approve release readiness.
@@ -114,6 +119,9 @@ uv run --with pytest python -m pytest -v -rs
 - Build/test reports record command, exit code, duration, stdout/stderr tail, and failure classification.
 - Reference comparison rejects missing, extra, duplicate, and nonfinite required rows before tolerance.
 - Warning-only quantities never change the blocking pass/fail result.
+- Reference comparison records per-row decisions and, only where the approved feature contract
+  makes each metric applicable, max absolute error, max relative or component-normalized error,
+  RMS error, and norm error.
 - Correction attempts stop when repeated failure indicates upstream contract ambiguity.
 
 ## Handoff