Round trip: code-only prop provenance is lost, so a rendered prop reads as an ordinary string prop

[nathanacurtis]

A code-only prop loses its provenance on round trip: the extension recording that it is a code-only prop, and which layer it came from, is absent when the rendered component is read back.

Evidence

egdsRemovablePill, REST baseline → render → read back:

   a11yLabel:
     $extensions:
       com.figma:
-        type: TEXT
-        source:
-          kind: codeOnlyProp
-          layer: A11y label

The prop itself survives — only the record of what it is disappears. A consumer reading the round-tripped spec cannot tell a code-only prop from an ordinary string prop, and a second render would not rebuild the hidden container it came from.

Where to look

figma-from-specs/src/Props/CodeOnlyProps.ts builds the hidden container and its bound child layers. Whether the layer name it writes matches what the read side looks for (processing.codeOnlyPropsPattern) is the first thing to check.

Note

Only visible since the variant-level slot fix removed the diff noise that buried it.

[nathanacurtis]

Same cause as #335, closing with it.

Code-only prop provenance is not lost. The component Nathan generated from the plugin panel for a component that had read back without it shows a11yLabel complete, with source.kind: codeOnlyProp and its layer name. Eight components rendered under distinct titles and read after all renders finished carried the provenance 8 of 8.

The missing provenance only appears when a bridge read is issued immediately after a render — the same measurement fault documented on #335, where the ruling-out of render, of --overwrite, of read nondeterminism, and of a settle window is recorded.