Windows handoff

Objective and starting point

Continue the existing Avalonia/WebView2 implementation on a Windows workstation. Start from the DevDuo repository and SSH remote in the README. No machine-specific checkout location, device name or simulator identifier is required.

The macOS WKWebView implementation has interactive evidence. Windows has only been cross compiled on macOS; it has no accepted native Windows runtime baseline yet. The task is to establish that baseline, repair platform-specific behavior, and then improve the host UI described in host-ui-roadmap.md.

Setup

Install Git and mise, enable real file and directory symbolic links, and use a checkout made with core.symlinks=true. This is mandatory for Windows contributors; see Contributing. Install WebView2 Runtime separately. From the repository root in PowerShell:

mise install
mise exec -- just setup
mise exec -- just doctor
mise exec -- just check
mise exec -- just serve

In a second terminal:

mise exec -- just build
mise exec -- just dev

Python, uv, Node, pnpm and just are managed by mise. The CLI selects the exact mise Python and locked environment; do not substitute the Windows Python launcher or global packages. See Development toolchain.

Windows automatically selects net10.0-windows and packages.net10.0-windows.lock.json. Do not regenerate the macOS lock file to resolve a Windows-only dependency problem. WebView2 uses the current user's application-data folder under DevDuo/WebView2; do not put that profile in the repository.

Code map

File	Responsibility
src/DevDuo/MainWindow.cs	Host window, controls, URL submission, diagnostics and preview sizing
src/DevDuo/NativeWebView.cs	Avalonia native-host lifetime and platform dispatch
src/DevDuo/WindowsWebViewPanel.cs	WebView2, native clipping, GDI shell rendering, scroll/theme observations
src/DevDuo/SafariScene.cs	Scene parsing and selected-tab geometry
src/DevDuo/SafariContainerOptions.cs	Shared container configuration
src/DevDuo/Fixtures/browser-observer.js	Actual desktop viewport/theme/scroll observation
src/DevDuo/macos/WebViewBridge.swift	macOS behavior to preserve while modifying shared code
config/safari-scenes.json	Eight measured body/fold mappings and 24 initial/scrolled reference states

Required Windows acceptance

1. Launch from a fresh checkout using only public files. Verify WebView2 initializes and reports a useful failure if the Runtime is unavailable. Record OS, runtime and DPI as generic platform metadata; exclude machine identifiers.
2. Check navigation, reload, keyboard focus, text entry, scrolling, native-view disposal, window resize and repeated device/mode switches. Confirm native children stay clipped to the independent screen mask and do not cover host controls.
3. Exercise Closed/Open × body 0/90/180/270 × initial/scrolled. In Open, exercise both tab-strip settings. Save original screenshots and state records in ignored captures/. Confirm actual page viewport dimensions, widget positions and collisions, rather than trusting requested options.
4. Check 100%, 150% and 200% display scaling plus movement between monitors when available. Distinguish CSS pixels, WebView2 zoom, native DIP and image pixels. Windows Fit uses WebView2 zoom and remains unverified; do not assume macOS scaling semantics apply.
5. In immersive mode confirm Safari widgets disappear, the complete requested scene becomes content, and no previous insets persist. Toggle the outer outline independently; the inner mask must remain.
6. Check multi-tab selected and unselected slots in all four Open body angles. The selected background uses the whole title container, including the close-button region; its title hit rectangle alone is too narrow. Preserve the common 14-point scene font and centered text.
7. Check initial/scroll transitions with the color fixture, theme-color, rendered-edge sampling and live page content. Windows uses tint/alpha composition, with no native backdrop blur implemented. Do not label that fallback as validated iOS Liquid Glass.

Expected Safari content sizes:

Scene	Initial	Scrolled
Closed 466 × 678	382 × 580	382 × 598
Closed 678 × 466	594 × 368	594 × 386
Open 951 × 669, multiple tabs	951 × 543	951 × 618
Open 669 × 951, multiple tabs	669 × 825	669 × 900
Open 951 × 669, single tab	951 × 589	951 × 618
Open 669 × 951, single tab	669 × 871	669 × 900

These are simulator-derived targets, not proof that Windows already matches. Closed body 180° retains the preceding landscape in the recorded clockwise sequence. See safari-scenes.md before changing the mapping.

Evidence and limitations

Checked-in configuration suffices for app execution. Canonical raw Safari images/native records are private local evidence and are not in a public clone. The full comparison verifiers require that original evidence; request an explicitly reviewed, separately transferred evidence set if needed. Do not manufacture passing records or treat a missing image as a pass.

Use uv run --locked devduo-tools png-compare for equal-scale PNG comparisons with explicit crops. uv run --locked devduo-tools contact-sheet accepts explicit image pairs and an optional --font; its presentation resizing is not a fidelity test. Both use locked Pillow. See the script inventory.

macOS Closed mode has real flow continuation below the floating address bar through WKWebView obscured insets. Windows currently reserves a smaller WebView2 frame. No equivalent native Windows solution has been established; investigate actual rendering and fixed-element behavior before claiming parity. See under-chrome-rendering.md.

Keep hardware millimeters, real corner radii, hinge angles and the iOS material kernel unknown. Finish with a platform validation note listing observed results, missing cases and exact reproduction steps. Keep future host UI changes separate enough to detect viewport regressions. Commit and push only when explicitly requested.

Language and command ownership

Use just for repository tasks and the uv/pnpm entries only for their ecosystems; see Development. On Windows, verify English, 简体中文 and system-default resolution, preference persistence, error/accessibility text and language changes while a page is scrolled. Compare before/after URL, scroll and actual viewport. Cross compilation and portable localization tests do not establish these native runtime results. See Localization.

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