fix(survey): box-none touch pass-through for non-overlay surveys

[pandeymangg]

What & why

While a survey was active, the host app received no touch input anywhere — the entire screen was blocked until the survey closed, regardless of placement. This breaks the box-none requirement from ENG-1342 (taps outside the active survey area must reach the host) and RN parity (pointerEvents="box-none").

Fixes ENG-1496.

Root cause

Two independent layers each blocked the full screen:

1. Modal route barrier — the survey was presented via RawDialogRoute, which always installs a full-screen ModalBarrier. A transparent barrierColor only makes it invisible; it still absorbs every pointer.
2. Full-bleed WebView — the native WebView hit-tests its whole rectangle, so even with a transparent page and a small survey card, it consumed every touch.

RN gets box-none for free from OS WebView hit-test pass-through (the page's pointer-events:none falls through). Flutter's platform-view embedding hit-tests its entire rect and ignores page-level pointer-events, so the host must mask pointers itself — and it needs the card's geometry to know where the card is.

Approach

Presentation now bifurcates on whether the survey uses a backdrop:

• Backdrop placements (overlay: dark/light) → keep the full-screen modal route. Blocking the host is correct here; the web runtime draws the dim and handles clickOutside via its existing onClose bridge call.
• Non-overlay placements (corner/inline cards) → a barrier-less root OverlayEntry wrapped in a _PointerMask. The WebView still paints full-bleed (so shadows render), but only pointers inside the reported card rect hit it; everything outside falls through to the host (box-none). Before geometry arrives, nothing is interactive.

To know the card rect, the survey page now reports it over the JS bridge:

• A new Geometry message carries the [role="dialog"] card's getBoundingClientRect().
• A requestAnimationFrame loop tracks the rect during open/step animations and posts only on change, then idles after ~1.5s of stability; MutationObserver + resize/orientationchange restart it on later changes.

Changes

• webview_event.dart — new GeometryEvent(Rect?) + parser for {type:'Geometry', data:{x,y,width,height}|null}.
• survey_html.dart — geometry reporting JS; scoped selector #fbjs [role="dialog"][aria-modal="true"].
• survey_webview.dart — overlay vs non-overlay presentation split, _PointerMask render object, geometry plumbing, unified teardown.

Testing

• flutter analyze clean; full suite (279 tests) green.
• New unit tests: geometry parsing (rect / null data / missing data / malformed-drop).
• New behavioral widget tests: outside-card tap → host; inside-card tap → WebView; pre-geometry → all taps pass through; backdrop → host fully blocked.

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
98.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud