Blank/empty window on macOS 26 (Tahoe) - BlazorWebView shows nothing, no errors

Description

After launching DevToys, only a completely empty window appears — no tools, no UI, no menu content. The app process runs without crashing, but the window never renders any content.

Environment

• macOS 26.6.1 (Tahoe), Apple Silicon (arm64)
• DevToys 2.0.9.0 (installed via Homebrew cask devtoys, which is the latest available version)

Steps to reproduce

1. Install DevToys via brew install --cask devtoys (or download the release zip directly)
2. Launch DevToys.app
3. An empty window appears with no functionality

What I've tried

• Fully uninstalled (brew uninstall --cask devtoys --zap, removing ~/Library/Caches/com.devtoys*, ~/Library/WebKit/com.devtoys*, ~/Library/Preferences/com.devtoys.plist) and reinstalled from scratch — same result.
• Cleared caches/preferences without full reinstall — same result.

Diagnostics

• No crash, no crash report generated in ~/Library/Logs/DiagnosticReports.
• No errors in unified system log (log show --predicate 'process == "DevToys"') during launch.
• lsof -p <pid> -i shows the DevToys process opens no network connections at all while running — suggesting the embedded BlazorWebView never successfully starts serving/loading its content.
• Process sampling shows normal, non-hung thread state (no deadlock).

Possible related cause

This matches the same symptom class as #1279 (macOS 15 Beta blank window), which was caused by BlazorWebView navigating to app://0.0.0.0 instead of app://localhost and fixed in #1284. Given macOS 26 is a very new OS release, this may be a similar regression in how WKWebView / BlazorWebView resolves its virtual host on this OS version.

Other WebView-based cross-platform frameworks are reporting similar blank/crashing WebView behavior specifically on macOS 26 Tahoe (e.g. wailsapp/wails#4592), which suggests this could be tied to an OS-level WKWebView behavior change in macOS 26 rather than something DevToys-specific.

Happy to provide more diagnostic info (samples, sysdiagnose, etc.) if useful.