mgbrowser v0.9.29 Experimental Preview

mgbrowser v0.9.29 Experimental Preview

Pinned unmodified Playwright 1.58.2 browser automation parity (connectOverCDP
over HTTP and WebSocket plus chromium.launch over --remote-debugging-pipe),
pure-Rust HTTP gzip/deflate/br decompression, responsive <picture> /
srcset and data:image/* decoding, credential-free cross-origin HTTPS
stylesheets and bounded CSS @import, CSS grid-template-areas / grid-area
2-column desktop layout, inline position: relative containing-block fallback,
flex-item BFC float isolation, viewBox-only and large-viewBox inline <svg>
sizing with Stylo style="..." and xmlns:xlink support, legacy vendor-prefixed
-moz-border-radius aliasing and Chromium-aligned DevTools Console css-parse
filtering, and real-site Boa DOM/JS compatibility (ECMAScript Annex B HTML-like
comments, DOM wrapper expandos, reflected HTML attributes, document.currentScript,
document.write, and blank/srcdoc <iframe> contentDocument/contentWindow).
Exact-source publication and public-install receipts are recorded in the dated
work log.

Linux x86_64 / X11 or XWayland, glibc 2.35 or newer. Rust 1.91.1, locked
dependencies, Apache-2.0 license, and pure-Rust implementation backends (zero
new crate dependencies).

Pinned Playwright 1.58.2 Automation & CDP Parity (v0.9.29)

• CDP Target Auto-Attachment, Isolated Utility Worlds & Pipe Transport (src/cdp.rs, src/main.rs, crates/mg-sparkle/src/js_browser/):
  • Full Target.setAutoAttach (flatten: true, waitForDebuggerOnStart),
    Runtime.runIfWaitingForDebugger, Page.createIsolatedWorld / utility-world
    Runtime.evaluate & Runtime.callFunctionOn (awaitPromise, returnByValue,
    element argument & return marshaling, executionContextCreated/Destroyed/
    Cleared even when page scripts are disabled with --disable-scripts),
    Page lifecycle events (frameAttached, frameNavigated, domContentEventFired,
    loadEventFired, lifecycleEvent, javascriptDialogOpening), DOM / CSS
    inspection, Network request/response events (including stylesheet HTTP 404
    reporting), Input mouse/keyboard/insertText, Emulation.setDeviceMetricsOverride,
    Browser.setDownloadBehavior (DownloadProgress / downloadWillBegin), and
    Chromium FD 3/4 NUL-delimited --remote-debugging-pipe + --headless
    virtual framebuffer mode.
  • Passes the unchanged tools/playwright/acceptance.mjs probe (playwright-core
1.58.2, both HTTP and WebSocket chromium.connectOverCDP paths) and
    tools/playwright/launch.test.mjs (chromium.launch with locators,
    screenshots, and downloads) while rejecting unknown CDP methods explicitly.

Real-Site CSS, SVG, HTTP & DOM Compatibility (v0.9.29)

• HTTP Decompression, Cross-Origin HTTPS Stylesheets & Bounded @import (crates/mg-chassis/):
  • Pure-Rust Accept-Encoding: gzip, deflate, br response decoding (flate2 +
    brotli-decompressor) with strict decoded-byte caps preventing zip/brotli
    amplification; credential-free cross-origin HTTPS <link rel="stylesheet">
    and @import loading (depth <= 4, cycle-checked, line/column-preserving)
    within the unchanged 16-sheet, 32-request, 2 MiB resource budget.
  • Responsive <img srcset> / <picture><source> candidate selection and
    bounded data:image/{png,jpeg,gif,svg+xml} inline URI decoding.
• Slashdot, Lobsters, Wikipedia & Rust-Lang Visual Layout Parity (crates/mg-sparkle/):
  • Byte-length-preserving author CSS normalization for legacy -moz-border-radius
    (plus corner variants, -moz-box-sizing, -webkit-box-sizing, -moz-opacity,
    -moz-box-shadow) preserving 1-based line/column diagnostic locations, paired
    with Chromium-aligned DevTools Console filtering of declarative CSS Syntax §5
    css-parse ignored declarations.
  • Stylo style="..." computed cascade on <svg> and SVG descendants, xmlns:xlink
    / xmlns:svg / xml:space / xml:lang attributes, inert <defs> / <symbol>
    / <metadata>, proportional svg_target_size scaling for large-coordinate
    viewBox icons within MAX_SIDE = 2048 / MAX_PIXELS = 1,048,576, and
    containing-width sizing for viewBox-only inline <svg> elements lacking
    width/height attributes.
  • CSS Grid grid-template-areas explicit track sizing and grid-area named
    placement resolution (rendering Wikipedia's Vector 2022 2-column desktop
    layout at >= 1120px), CSS 2.1 §10.1 inline position: relative containing-block
    fragment union fallback, and isolated float state across Taffy flex/grid item
    measurement and BFC painting (fixing clear: both story lists inside flex
    containers on lobste.rs).
• Real-Site Boa JS & DOM Compatibility (crates/mg-sparkle/src/js_browser/boa/):
  • Byte-length-preserving ECMAScript Annex B.1.1 <!-- / --> comment
    normalization, DOM wrapper JS expando property storage with worker memory
    accounting and strict/sloppy read-only IDL semantics, reflected HTML element
    properties, <script>/<style> text serialization, document.currentScript,
    bounded document.write/writeln/open/close, and subdoc:-backed
    same-origin blank/srcdoc <iframe> contentDocument and contentWindow.
• Measured WPT Coverage:
  • Static flexbox reftest lane advances from 532 to 541 PASS / 408 FAIL /
    62 UNSUPPORTED of 1,011 (+9 new passes over v0.9.28 across SVG flex
    items, data:image/* flex-basis content sizing, and dynamic inline-size
    float/BFC measurement, zero losses; expectations.json ratcheted to protect
    all 541 passes).
  • Separate real-Browser Window lane retains 16 / 16 files and 79 / 79 final
    subtests (100%).