mgbrowser v0.9.30 Experimental Preview

mgbrowser v0.9.30 Experimental Preview

Responsive CSS Grid ([named-lines], fit-content(), repeat(auto-fill | auto-fit, ...)), generalized intrinsic box sizing (min-content, max-content,
fit-content), CSS box-shadow and text-shadow Gaussian blur rendering,
multi-stop (2..=16) linear/repeating-linear/radial/repeating-radial gradients,
CSS 2D transform (translate, scale, matrix), clip: rect(...) /
clip-path: inset(... round ...) and text-overflow: ellipsis, pure-Rust HTML5
<canvas> 2D immediate-mode rasterization and PNG export, browser-hosted ES
<script type="module"> execution, DOM Observers (MutationObserver,
ResizeObserver, IntersectionObserver) and CustomElementRegistry
(window.customElements), @font-face unicode-range subset filtering,
large-page (> 1 MiB) CDP utility-world automation (news.google.com), honest
Linux desktop User-Agent compatibility (www.npr.org), independent per-tab
page zoom (25%..=500%), persistent user-local localStorage, and tab session
snapshot & restore. 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).

CSS Visual Parity, Responsive Grid & Intrinsic Sizing (v0.9.30)

• Named Grid Lines, fit-content() & repeat(auto-fill | auto-fit) (crates/mg-sparkle/):
  • Parses explicit [line-name] line lists on grid-template-columns and
    grid-template-rows, synthesizes implicit <area>-start / <area>-end
    lines from grid-template-areas, resolves grid-column / grid-row named
    lines and span <name> placements, maps fit-content(<length-percentage>)
    tracks, and expands repeat(auto-fill | auto-fit, ...) track definitions
    against container dimensions while collapsing empty auto-fit tracks to
    0px (rendering MDN Web Docs --layout-no-sidebar-extended in full styled
    layout without readable-flow fallback).
• Generalized Intrinsic Sizing & HTML5 <canvas> Replaced Layout (crates/mg-sparkle/):
  • Supports min-content, max-content, and fit-content keywords across
    width, height, min-width, min-height, max-width, max-height, and
    flex-basis across block, inline, flex, and grid formatting contexts, plus
    HTML5 <canvas> 300x150 intrinsic fallback and HTML width/height
    attribute sizing.
• Shadows, Multi-Stop Gradients, 2D Transforms, Clipping & Ellipsis (crates/mg-sparkle/):
  • box-shadow (0..=8 reverse-painted layers) with analytical rounded-rect
    signed-distance Gaussian blur, outer border-box cutout masking, and inset
    padding-box clipping; text-shadow (0..=4 layers) with blurred glyph
    rasterization beneath text runs.
  • Multi-stop (2..=16) linear-gradient, repeating-linear-gradient,
    radial-gradient, and repeating-radial-gradient backgrounds with CSS
    Images 3 stop fixup and color-transition midpoints.
  • CSS 2D transform (translate, translateX, translateY, translate3d,
    scale, scaleX, scaleY, matrix) with transform-origin, stacking
    context creation, and position: fixed containing-block establishment.
  • Screen-reader clip: rect(...) and clip-path: inset(... round ...)
    zero-area visual hiding and rounded inset clipping, plus single-line
    text-overflow: ellipsis (U+2026) truncation.
• Measured WPT Coverage:
  • Static flexbox reftest lane advances from 541 to 558 PASS / 391 FAIL /
    62 UNSUPPORTED of 1,011 (+17 genuine new passes over v0.9.29, zero
    losses; expectations.json manually ratcheted to protect all 558 passes
    and 949 runnable cases).
  • Separate real-Browser Window lane retains 16 / 16 files and 79 / 79 final
    subtests (100%).

HTML5 <canvas> 2D, ES Modules, DOM Observers & Web Components (v0.9.30)

• Pure-Rust HTML5 <canvas> 2D Engine (crates/mg-sparkle/src/js_browser/boa/canvas.rs, crates/mg-chassis/):
  • Implements HTMLCanvasElement.getContext('2d') (<= 2048x2048, <= 1,048,576
    pixels, worker-memory-accounted premultiplied RGBA buffer): fillRect,
    strokeRect, clearRect, subpaths (beginPath, moveTo, lineTo,
    quadraticCurveTo, bezierCurveTo, arc, arcTo, ellipse, rect,
    roundRect), Path2D, nonzero/evenodd scanline fill & dashed/joined
    stroke, clip, affine DOMMatrix state stack, CanvasGradient &
    CanvasPattern, shadow blur, Porter-Duff globalCompositeOperation,
    zero-FD embedded bitmap fillText / strokeText / measureText,
    getImageData / putImageData / drawImage, pure-Rust LZ77+Huffman PNG
    encoding (toDataURL / toBlob), and live document.resources projection
    into Sparkle's styled layout painter.
• Browser-Hosted ES <script type="module">, Observers & Custom Elements (crates/mg-sparkle/src/js_browser/boa/, crates/mg-chassis/):
  • Preloads bounded inline and external <script type="module"> graphs (<= 16
    modules, <script type="importmap"> specifier resolution, live namespace
    bindings, import.meta.url, and parent-brokered same-origin dynamic
    import(), with nomodule suppression in browser sessions while keeping
    standalone BoaPageRealm::start / boa_worker assertions untouched).
  • Implements microtask-batched MutationObserver (childList, attributes,
    characterData, subtree), layout-synced ResizeObserver and
    IntersectionObserver, and CustomElementRegistry (customElements.define,
    get, whenDefined, upgrade, connectedCallback, disconnectedCallback,
    attributeChangedCallback), plus Element.animate / getAnimations and
    window.visualViewport.

Real-Site Compatibility, Large-Page CDP & Desktop Session UX (v0.9.30)

• @font-face unicode-range Filtering, Wikipedia Sprite/SVG/JS Compatibility & Large-Page CDP (crates/mg-sparkle/, crates/mg-chassis/):
  • Filters @font-face rules against document text codepoints before fetching
    font binaries so multi-subset stylesheets (such as MDN's Cyrillic/Greek/Latin
    font sheets) download matching subsets instead of exhausting MAX_FONTS on
    unused scripts.
  • Updates USER_AGENT to "Mozilla/5.0 (X11; Linux x86_64) mgbrowser/0.9.30",
    resolving CDN crawler-signature TLS tar-pitting on sites such as www.npr.org.
  • Adds window.Image (new Image(width?, height?)), raises the browser-session
    addEventListener cap to 2,048 memory-accounted listeners (while keeping
    the standalone BoaPageRealm::start contract cap at 32), supports bounded
    external/inline SVG <style> blocks and acyclic internal <use href="#id">
    sprite references, resolves intrinsic background-size: auto and
    background-position offsets with element-box clipping for CSS sprites,
    multiplies color alpha (color: transparent) during text painting,
    suppresses spurious gradient diagnostics for MediaWiki's transparent
    linear-gradient(transparent, transparent), url(...) fallback idiom, and
    replaces per-reply full-HTML string materialization with zero-allocation
    serialized-byte validation (www.wikipedia.org executes all page scripts
    and renders its SVG wordmark sprite with 0 JS/CSS/SVG errors or warnings).
  • Synthesizes a bounded (<= 128 KiB, <= 2,500 nodes) <script>-free DOM
    snapshot when opening an on-demand CDP automation session on oversize (> 1 MiB) HTML documents or after page-script budget exhaustion so Playwright
    page.title() and utility-world queries succeed well within the 2-second
    active wall budget on pages like en.wikipedia.org, news.google.com, and
    developer.mozilla.org.
• Per-Tab Page Zoom, Persistent localStorage & Session Restore (crates/mg-chassis/, src/):
  • Independent per-tab page content zoom (25%..=500%, Alt+= / Alt+- /
    Alt+0, Ctrl+MouseWheel, address-bar zoom badge, and Hamburger Menu zoom
    row) separate from whole-browser UI scale.
  • Atomic 0o600 (O_NOFOLLOW, flock, <= 512 KiB) user-local persistence
    for window.localStorage (local-storage.json, cleared on Ctrl+Shift+Delete)
    and open-tab session snapshots (session.json, restorable via Menu ->
    Restore session, chrome://newtab, or --restore-session).

Remaining Limitations

• Modern-web compatibility remains bounded: cross-origin dynamic import(),
  WebGL/WebGPU, HTML5 <video>/<audio> codecs, Service Workers, cross-origin
  CORS preflights, CSS 3D transforms/keyframe animations, and full Chromium
  multi-process site isolation are not implemented.
• Resource budgets (16 stylesheets, 32 requests, 2 MiB total resources,
  1 MiB page script source, 2048px / 1,048,576-pixel image/canvas cap) and
  the seccomp-confined script worker (RLIMIT_NOFILE = 3, RLIMIT_FSIZE = 0,
  not a whole-browser sandbox) remain unchanged. Do not use this preview for
  banking, sensitive authenticated browsing, or arbitrary hostile websites.