fix: embedded view collapsing to zero height in a column container

[thomson-t]

Background

• RoktEmbeddedView styles its own native view with flex: 1 alongside the height it receives from the native SDK:

  style={[styles.widget, { height: this.state.height }]}

• In Yoga, flex: 1 expands to flexGrow: 1, flexShrink: 1, flexBasis: 0%, and flexBasis takes precedence over height on the parent's main axis. Whenever the view is rendered inside an auto-height column container, the base size resolves to 0, flexGrow has no free space to distribute, and the view stays 0pt tall.

• The result is a silent failure that looks like a selection or targeting problem: the placement is selected, PlacementReady and PlacementInteractive fire, the native SDK reports the measured height to JS, and nothing is ever visible — so no impression or view signal follows.

• This is easy to miss because it depends entirely on the immediate parent. It works when the parent does not constrain the main axis, for example as a direct child of a ScrollView as in RoktSampleApp, which is the arrangement used in our sample app and docs. Wrapping the component in a plain <View> — a very common integration pattern — is enough to trigger it.

What Has Changed

• Replaced flex: 1 with alignSelf: "stretch" in styles.widget in both rokt-embedded-view.ios.tsx and rokt-embedded-view.android.tsx.
• alignSelf: "stretch" still gives the widget the full available width in a column layout, but leaves the main axis untouched so the measured height applies.
• Added a comment on both platforms explaining why flex: 1 must not be reintroduced.
• No public API change. No change to the height/margin event plumbing.

Screenshots/Video

Reproduced with a minimal app that renders <RoktEmbeddedView> inside <View style={{ marginBottom: 24 }}> (an auto-height column parent), on iOS 26.4 simulator, React Native 0.81.5, New Architecture enabled.

Before — placement selected and height reported, container never grows:

selectPlacements(...) placeholders={"RoktEmbedded1":74}
RoktEvents: PlacementReady
RoktEvents: PlacementInteractive
WidgetHeightChanges: RoktEmbedded1 height=186
WidgetHeightChanges: RoktEmbedded1 height=470.67
WidgetHeightChanges: RoktEmbedded1 height=530.33
container onLayout height=0        <-- never grows, nothing rendered

After — same app, same parent, no consumer-side change: the layout renders at its
reported height.

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• Tests: the package has no JS test harness (Rokt.Widget/package.json → "test": "echo \"Error: no test specified\""), so there is nowhere to land a unit test for this. A layout regression test needs a renderer assertion on the resolved height, which would mean introducing jest + react-test-renderer to the package. Happy to do that as a follow-up if we want it.
• Docs: no doc change needed — the README example does not set a wrapper style, and it now works in any container.
• Verified on: stock flex: 1 fails and the patched style renders, on both 4.11.2 and 4.12.2, inline and inside a Modal. Behaviour as a direct ScrollView child is unchanged.
• Android caveat unrelated to this PR: on RN 0.83+ with the New Architecture, versions before 5.0.1 never deliver the height to JS at all (fixed in fix(android): render embedded placements on New Architecture via EventDispatcher #272). This change is necessary but not sufficient on those older versions.
• The same flex: 1 pattern exists in mParticle/react-native-mparticle (js/rokt/rokt-layout-view.{ios,android}.tsx), which ports this component as RoktLayoutView. Worth porting this fix there too.

Reference Issue (For employees only. Ignore if you are an outside contributor)

• No ticket — found while investigating an embedded placement that selected successfully but never rendered.

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