[Bron Davies (brondavies)]

Summary:

On macOS, a ScrollView doesn't scroll while the pointer is over a multiline TextInput inside it. RCTWrappedTextView keeps its text in an NSScrollView, which keeps every scroll event it's sent, even with nothing to scroll.

Its scroll view now passes on any scroll its text can't follow. While the text fits, or with scrollEnabled={false}, that's every scroll. Once the text overflows, it's a scroll past the top or bottom. It decides when a gesture starts: on each wheel notch, or on a trackpad's MayBegin or Began. So a gesture and its momentum stay with one scroll view.

Test Plan:

RNTester-macOS (Debug, arm64, Xcode 27.1, macOS 26.6.2). The Playground had a ScrollView holding an empty multiline TextInput, one with 30 lines, and a 600pt spacer. I sent wheel events from lldb to the text view hit-tested under each input:

• On main (same build, the scroll view's class swapped back to RCTUIScrollView), the ScrollView stays put over both inputs, even with the long one scrolled to its end.
• With this change, a notch over the empty input scrolls the ScrollView 30pt, and back. Over the long one, the input scrolls to its end (14 notches), then the ScrollView scrolls. Going up, the input scrolls back to its top, then the ScrollView follows.

It's the same in an app on 0.83.0 with this patched in.

I checked trackpad gestures in a standalone AppKit harness: the MayBegin and Began events decide, and the rest follows. I didn't check them with a real trackpad.

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