[Problem/Bug]: Windows.Storage.Streams.Buffer length is always zero in WebView2

[josephsobhy]

What happened?

Buffer.Length always return zero in webview2.

Same code in webview1 returns the correct value.

const Windows = chrome.webview.hostObjects.sync.Windows;
const capacity = 10;
const buffer = new Windows.Storage.Streams.Buffer(capacity);
console.log(buffer.length); // 0

A more practical example to read bytes from a file.

const appRootFolder = Windows.Storage.ApplicationData.current.localFolder;
await appRootFolder.createFileAsync('download.txt', Windows.Storage.CreationCollisionOption.openIfExists);
const file = await appRootFolder.getFileAsync('download.txt');
await Windows.Storage.FileIO.writeTextAsync(file, "abcdz");

Windows.Storage.FileIO.readBufferAsync(file)
    .then((buffer) => {
        const dataReader = Windows.Storage.Streams.DataReader.fromBuffer(buffer);
        const bytes = new Uint8Array( buffer.length );
        console.log(`Buffer length is ${buffer.length}`);
        console.log(dataReader.readBytes(bytes));
        // Manually reading the first 5 bytes instead of using buffer.length
        const bytes2 = new Uint8Array( 5 );
        console.log(dataReader.readBytes(bytes2));
    });

Importance

Blocking. My app's basic functions are not working due to this issue.

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

126.0.2592.81

SDK Version

1.0.2535.41

Framework

WinUI2/UWP

Operating System

Windows 10

OS Version

No response

Repro steps

const Windows = chrome.webview.hostObjects.sync.Windows;
const capacity = 10;
const buffer = new Windows.Storage.Streams.Buffer(capacity);
console.log(buffer.length);  // 0

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

No, this never worked

Last working version (if regression)

No response