FormGroupHeading gains an anatomy element absent from the baseline

[nathanacurtis]

The round-trip adds structure the baseline does not have. Every other finding in the catalog run is loss; this is the only additive one.

Evidence

FormGroupHeading:

path	baseline	round-trip
anatomy.labelRow	(absent)	{type: container, detectedIn: "custom=true, role=H3"}
default.elements.labelRow	(absent)	full styles block (layout mode, wrap, sizing, itemSpacing)
variants[1].layout	(absent)	[{root: [{children: [{labelRow: [heading, requiredIndicator]}]}]}]

The added element nests existing elements (heading, requiredIndicator) beneath it, so the layout tree gains a level.

Fixtures

• FormGroupHeading — the only clear instance in the catalog

variants[*].layout differences appear in 6 aligned components and may share this cause, but they were not individually characterised and should not be assumed related.

Where

Undetermined. Whether the render creates a wrapper that was not in the spec, or the read invents one from the rendered structure, is not established.

Caveat

This component also has a variant-count mismatch (1 → 3), covered by the variant-count investigation issue. Resolve that first — some of the added structure may be misalignment rather than invention.

Part of #281.

[nathanacurtis]

Fixed in specs-from-figma ec9d665 on feat/figma-from-specs.

Cause

collectAxes in packages/figma-from-specs/src/Variants/Variants.ts treated any string+enum prop as a variant axis, without checking whether it was code-only. FormGroupHeading's role is an enum code-only prop, so render gave the component set a real role variant property — while CodeOnlyProps separately refused to build its instance layer, since enum/instance code-only props are not supported. The two paths disagreed, and the set ended up with an axis the spec never declared.

Nothing was invented on the read side. The extra axis forced a second variant, and the slot content (labelRow, heading, requiredIndicator, already present in slotContentExamples) surfaced into component anatomy along with it. The added element was a downstream symptom, not the defect.

Fix

Code-only props are now skipped when collecting variant axes, so an unsupported code-only prop is skipped in both paths rather than half-rendered.

Verification

Round-tripped egdsFormGroupHeading against its current baseline, before and after:

section	before	after
api	5 differences	2
variants	7 differences	0
examples	2 differences	2

Every symptom recorded in this issue is gone: anatomy.labelRow, default.elements.labelRow, the anatomy.children slot→container flip, and the nested variants[0].layout[0].root[0]. The variant-count mismatch this issue flagged as a prerequisite is also resolved — it had the same cause.

Remaining, tracked separately

• props.role is now dropped rather than half-rendered — expected, since enum code-only props are unsupported by render.
• anatomy.children.detectedIn casing: Custom=True vs custom=true.
• slotContentExamples…labelRow.styles.width 301 vs 100, following the skipped layoutSizingHorizontal: FILL.
• slotContentExamples…requiredIndicator.styles.visible loses its $binding.