macOS 27 packaged WKWebView + NSGlassEffectView: DirectTouch objc_initWeak and custom-protocol objc_storeWeak SIGABRT

[hongguang121]

Moved from #198 at @FabianLars's request. This is not the corner-radius / edge-alignment bug.

On macOS 27.0 (26A428), Apple M1, Tauri 2.11.2 / wry 0.55.1 / tao 0.35.2, a packaged .app (npm run tauri:build, custom-protocol on) with:

• transparent: true, titleBarStyle: Overlay, decorations: true, resizable: true
• one public NSGlassEffectView inserted as a theme-frame sibling behind the Tao/WK host (not a WK subview; not live addSubview on resize)

hits two separate AppKit Namespace OBJC SIGABRTs. tauri dev with the same glass view does not.

I am not asking window-vibrancy to swizzle DirectTouch or Gesture-Fusion. These look like AppKit/WebKit crashes that apply_liquid_glass / the 0.8 content_view reparent will hit on packaged Tauri windows. Related: PR #199, Tauri PR #14454.

Environment

Machine	MacBookPro17,1 (Apple M1)
OS	macOS 27.0 (26A428), User
Window	transparent: true, decorations: true, titleBarStyle: Overlay, resizable: true
Glass	one NSGlassEffectView sibling behind the Tao/WK host, insert once
Stack	Tauri 2.11.2, wry 0.55.1, tao 0.35.2, WKWebView

Crash 1 — native resize (fromServer:YES)

Incident Identifier: 00238567-94AA-41AB-91CA-689FB9EAF214
IPS: aether-agent-2026-09-14-100015.ips (happy to attach)

objc_initWeak → swift_unknownObjectWeakInit
_NSViewLayout → -[NSWindow _layoutViewTree]
-[NSWindow _oldPlaceWindow:fromServer:]
-[NSWindow _resizeChangedForDirectTouch:locationInWindow:incrementalDelta:modifierFlags:]
-[_NSGFGestureEnvironment _updateGestureRecognizer:]

Termination: Namespace OBJC, Code 1. There is no application frame between _NSViewLayout and objc_initWeak.

CSS overlay setSize handles cannot intercept this: DirectTouch is dispatched from -[NSWindow sendEvent:] before WK.

Crash 2 — custom-protocol first paint

Incident Identifier: 8F80BDC0-2F0A-4768-A7EC-CBF7E03BC305
IPS: aether-agent-2026-09-14-152837.ips (happy to attach)

objc_storeWeak
-[NSWindow _setFirstResponderIvar:]
-[NSWindow _realMakeFirstResponder:]
WebKit::WebURLSchemeHandlerCocoa::platformStartTask

Same Namespace OBJC abort. Dev loads HTTP devUrl; packaged loads via WKURLSchemeHandler. That is why debug is clean and the .app is not.

Why this matters for 0.8 / Tauri 2.12

PR #199 / the README tell apps to reparent WKWebView into the glass contentView. On tao 0.35 that is extra-unsafe (TaoView taoState / ViewState.ns_window is an objc2::rc::Weak; live reparent + mouseMoved: can objc_loadWeakRetained SIGSEGV).

Even without reparenting — glass as a behind-WK sibling, insert once — packaged DirectTouch layout still aborts inside the glass Swift subtree. So sibling vs content_view is not a fix for crash 1.

Please do not treat “put WK inside NSGlassEffectView.contentView” as a safe default for packaged Tauri windows on macOS 27 until this is understood. Apple Feedback Assistant reports are drafted; FB numbers in a follow-up if/when they exist.

Does not reproduce

• tauri dev / HTTP devUrl + JS setSize (_setFrameCommon:fromServer:NO)
• Packaged build without NSGlassEffectView in the theme frame (standard AppKit chrome + CSS-only glass). Native resize then works.

Minimal reproduction

1. Empty Tauri 2.11.2 project. Keep custom-protocol (what tauri build uses).
2. Window config:

{
  "decorations": true,
  "titleBarStyle": "Overlay",
  "hiddenTitle": true,
  "transparent": true,
  "resizable": true
}

3. Insert one NSGlassEffectView as a sibling behind the existing content view. Do not reparent WKWebView into the glass contentView. Do not addSubview again on resize.
4. npm run tauri:build. Fully quit any previous Dock copy. Launch the .app.
5. If it dies on first paint → crash 2. If it launches, drag a native window edge → crash 1.

We currently ship packaged builds without NSGlassEffectView (CSS glass only) for this reason.