Text + Text concatenation via Compose AnnotatedString

[vincentborko]

What

Implements Text + Text concatenation with per-segment styling on Android, rendered as a single Compose AnnotatedString.

static func + (Text, Text) was previously fatalError(), so any SwiftUI that builds a multi-style inline string by concatenation (per-segment color / weight / size / italic / monospaced / underline / strikethrough / gradient foreground) could not run on Android.

How

Both runtimes feed one ordered [TextRun] model, folded into a single AnnotatedString (each run's styling as a SpanStyle) and rendered by the shared _Text.Render path — so environment-level concerns (text alignment, line limit + truncation, tracking, line spacing, material3Text) behave like a normal Text, with no duplicated render logic:

• Skip Lite (transpiled) — a native + operator (Text.plus, // SKIP DECLARE: operator fun plus). A styled Text applies its style as an environment modifier that can't be read back at render time, so each operand's styling is captured as TextRunStyle data where the modifier is applied (.foregroundColor, .font, .bold, …), mirroring SkipSwiftUI's TextRun.
• SkipFuse — // SKIP @bridge public init(bridgedRuns:colors:fontSizes:fontWeights:flags:) accepts primitive-only per-run descriptors and folds them into the same [TextRun]. The foreground resolves to a solid color when it is one, otherwise a Compose brush (gradients via SpanStyle(brush:)). localizedTextString(), asColor, and asBrush are @Composable, so they're resolved in the @Composable scope before the (non-composable) builder lambda.

Note (supersedes the original draft): the native Skip Lite + operator is implemented here now. Earlier this PR left + unimplemented and reached the run model only via the bridge; it has since been unified so Text + Text works in both Skip Lite and SkipFuse through the one _Text-with-runs path.

Dependencies / pairing

• Requires Compose statement-level View operators (e.g. Text + Text) skipstone#255 — the transpiler fix that composes a bare, statement-level Text + Text. Without it, an unconstrained concatenation (e.g. directly in a VStack) is constructed but never composed (zero size); it only renders when wrapped in another view modifier like .frame(...).
• Pairs with Text + Text concatenation via a run model skip-fuse-ui#118 — the SkipSwiftUI side that captures styling as data and calls the bridgedRuns initializer.

Testing

Verified on an Android emulator (Showcase "Text Concatenation" playground): per-run colors, weights, sizes, italic/monospaced, underline/strikethrough, gradient foreground, and multi-line wrapping all render as a single flowing styled block — both bare/unconstrained and width-constrained.

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• AI was used to assist with this PR.

🤖 Generated with Claude Code

[marcprux]

We might consider merging this work with #434 to support the + operator in Skip Lite as well as Fuse.

[vincentborko]

Nice idea, I'll update with the best of both worlds shortly! ;)

[vincentborko]

all working cleanly now 👍