Jetpack Compose splits Korean between syllables, but the stacked 'R/u/l/e' label came from how a Row measures

Five broken spots, all inside shared components

Every defect sat in a shared component. The September 25 QA was run by four AI coding agents in turn: one per app, then a fourth that reproduced every finding with its own screenshots and read the code behind each root cause. The table copies the symptoms recorded that day in the CHANGELOG and in code comments.

The three apps are Compress Image, Flip & Rotate Image and Convert Image JPG PNG WEBP, and all of them depend on the same core/designsystem module. Commit 633c3dd touched 57 files, but the line-breaking work is concentrated in a handful of files in that module.

Compose treats Hangul syllable boundaries as break points

LineBreak.WordBreak decides where Compose may split a word. The LineBreak.WordBreak reference describes Default as the locale's default word-breaking rules: Latin scripts break between words, while languages that don't use whitespace (the page's example is Japanese) can break between characters. Phrase does not insert breaks between characters of the same phrase unit and is "ideal for short text such as titles and UI labels". Both values were added in Compose 1.3.0.

Korean does put spaces between words, yet the apps still split inside them. A comment in the repository's WordWidth.kt records why: Compose's own minimum intrinsic width treats every Hangul syllable as a break point. So the grid believed "오른쪽으로" fitted in the width of a single syllable, kept two columns and cut the word in the middle.

The platform adds its own limit. Per the LineBreakConfig reference, phrase-based breaking (LINE_BREAK_WORD_STYLE_PHRASE) arrived in API level 33 (Android 13), its support depends on the locale, and it has no effect where the locale is unsupported. These apps have minSdk 29, which means Phrase does nothing on Android 10 to 12.

WordBreak.Phrase lives in one shared TextStyle

A single style() function in SugarType.kt builds every step of the type scale, so it is the only place that sets lineBreak. No screen code changed.

private val WordAwareBreak =
    LineBreak.Simple.copy(wordBreak = LineBreak.WordBreak.Phrase)

private fun style(weight: FontWeight, size: Int, line: Int, spacing: Boolean = false) = TextStyle(
    // fontFamily, fontSize, lineHeight, letterSpacing ...
    lineBreak = WordAwareBreak,
)

If your Compose app has Korean screens, set Phrase once in the shared TextStyle and do not add it to individual Text calls. Per-screen settings get forgotten the next time someone adds a screen. The same comment says a word wider than the line still breaks. (The Korean hero titles also got zero-width break points after the "·" separator.)

The longest word decides how many columns fit

The option tile grid picks its column count from the minimum intrinsic width each tile reports. For Korean that number is one syllable wide, so the module gained a function that measures whole words: split on whitespace, measure each word on one line, return the widest.

text.split(Regex("\\s+")).filter { it.isNotEmpty() }.maxOfOrNull { word ->
    measurer.measure(word, style, softWrap = false, maxLines = 1).size.width
} ?: 0

Tile titles and subtitles report that value as their minimum intrinsic width (minIntrinsicWidthAtLeast, a small LayoutModifier), and the grid compares it with the cell width.

val cols = when {
    requested == 1 -> 1
    largeFont -> 1
    measurables.any { it.minIntrinsicWidth(Constraints.Infinity) > cellWidthFor(requested) } -> 1
    else -> requested
}

In app code, Flip & Rotate Image's four action buttons use the same function. When the longest word of any label is wider than half the screen minus the button chrome, the buttons go one per row instead of two.

From 150% font scale, stack; for chips, use FlowRow

One constant defines "large font": LARGE_FONT_SCALE = 1.5f in Chips.kt. At or above it, three components switch to a vertical layout.

• Segmented control: the segments become option tiles stacked top to bottom. The check icon went too; it was taking a third of a segment's width.
• Option tile grid: one column, whatever was requested.
• Flip & Rotate Image's action buttons: one per row.

The choice chip row used to be a Row with horizontalScroll. Chips past the edge simply hid there, and nothing told the user that "Web" or "Custom" existed. With FlowRow they wrap onto the next line.

// before: Row(modifier = modifier.horizontalScroll(rememberScrollState()), ...)
FlowRow(
    modifier = modifier.fillMaxWidth(),
    horizontalArrangement = Arrangement.spacedBy(SugarSpacing.sm),
) { /* FilterChip ... */ }

A Row from four days earlier, and a button width that missed by 2 px

"R/u/l/e" had nothing to do with Korean. The label/value row came from the design v2 commit (33e6cc0, 2026-09-21), written together with an AI coding agent. It was a Row with Modifier.weight(1f, fill = false) on the label and no weight on the value. A Row measures unweighted children first, so a long value took the whole width and the label folded into the few pixels left, one letter per line.

Four days later, the cross-check agent in the device QA flagged this structure while reading the code behind the finding. The new PairLayout measures each slot's natural width (maxIntrinsicWidth) first. If the sum fits the line, they sit side by side; if not, the value moves under the label.

The second mistake was a number. The action-button chrome adds up to exactly 76 dp: 24 dp of OutlinedButton padding on each side, a 20 dp icon and an 8 dp gap. According to the code comment, at 130% font "오른쪽으로" measured 2 px under the space that exact figure left, and it still wrapped. The value was fixed at BUTTON_CHROME = 84.dp, the exact chrome plus 8 dp of slack.

The same defect came back by another route. In the HWP Viewer SugarDoc device test on 2026-10-06, the format placeholder split into "HW/PX" (S21) and "HW/P" (S20) at 200% font. That app uses the same design-system module, so Phrase was already on, but "HWPX" is a single word and a word wider than its box still breaks. Pinning the placeholder to one line and letting it shrink to fit fixed that, but "HWP 3.0" did not fit even at the smallest step and got clipped to "HWP 3.(" instead. The final fix shortened placeholder names to four characters or fewer ("HWP3"), while the badge and the TalkBack label keep "HWP 3.0".

Checklist

After the September 25 fixes, a separate agent checked every fix on the device and a person checked again by hand, across 1.0/1.3/2.0 font scale, Korean and English, light and dark, and landscape, with no regressions. The list below is drawn from these fixes.

• The shared TextStyle sets lineBreak = LineBreak.Simple.copy(wordBreak = LineBreak.WordBreak.Phrase). Android 12 and lower ignore it, so the items below still matter.
• Layouts that choose a column count look at the longest word, not Compose's minimum intrinsic width.
• At fontScale 1.5 and above, segmented controls, grids and button rows switch to a vertical layout.
• No option hides behind horizontal scrolling (FlowRow).
• Label/value rows are not left to Row weights.
• Computed padding includes the error seen on a device (8 dp this time).
• Single-word short labels, such as format names like "HWPX", fit their box at 200% font.

One item is still open: on the input screen of Convert Image JPG PNG WEBP, the size badge wraps as "JPEG · 1.3 / MB", recorded as a cosmetic leftover in the 2026-09-25 CHANGELOG entry. The full pre-release check list is in What to check before shipping an AI-built Android app.

FAQ

More AX notes

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All notes on Android development · All AX notes