Android 0.86: TextAttributeProps lineHeight ignores maxFontSizeMultiplier (downstream report for #58982) #59022

Description

React Native 0.86.0 Android TextAttributeProps converts lineHeight with toPixelFromSP(value) while fontSize passes maxFontSizeMultiplier. This makes capped Text line spacing continue to grow on Android. iOS and Android TextInput already apply the cap.

Related: #56578, #58124, and the existing open fix #58982. This downstream report records the separate lineHeight-only candidate requested by our app owner; #58982 appears to cover the same cap defect and should be preferred over duplicate implementation work.

Reproduction

On Android API 33 (linear font scaling), compare font scale 1.0 and 2.0:

<Text maxFontSizeMultiplier={1.35} style={{fontSize: 26, lineHeight: 33}}>
  First line{'\n'}Second line
</Text>

At 2.0 the font is capped at 35.1 dp but lineHeight becomes 66 dp rather than the capped 44.55 dp. On API 34+ account for nonlinear SP conversion before applying the cap. Expected: cap both fontSize and lineHeight. No crash logs.

Candidate Kotlin patch

Prepared against RN 0.86.0; not Gradle-tested in this session. Regression cases should cover fromReadableMap/fromMapBuffer, cap updates, uncapped/zero cap, allowFontScaling=false, and nonlinear font conversion. Existing PR #58982 has broader test coverage.

diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/text/TextAttributeProps.kt b/ReactAndroid/src/main/java/com/facebook/react/views/text/TextAttributeProps.kt
--- a/ReactAndroid/src/main/java/com/facebook/react/views/text/TextAttributeProps.kt
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/text/TextAttributeProps.kt
@@ -39,7 +39,8 @@
           if (value == ReactConstants.UNSET.toFloat()) {
             Float.NaN
           } else {
-            if (allowFontScaling) toPixelFromSP(value) else toPixelFromDIP(value)
+            if (allowFontScaling) toPixelFromSP(value, maxFontSizeMultiplier)
+            else toPixelFromDIP(value)
           }
     }
 

The companion last-line descent report includes our proposed CustomLineHeightSpanTest.kt; those tests cover descent geometry, not this independent cap defect.