mgbrowser v0.9.15 Experimental Preview

mgbrowser v0.9.15 Experimental Preview

v0.9.15 adds physical justify-content:left/right placement to the existing
bounded flex/grid layout adapter. This increment uses the already locked Rust
Stylo and Taffy crates; it adds no dependency, worker profile, browser protocol
or resource allowance. The full browser, CSS and WPT milestones remain open.

Linux x86_64 / X11 or XWayland, glibc 2.35 or newer. Rust 1.91.1 and locked dependencies.

Physical content justification

• Horizontal LTR flex rows keep the group against its physical left/right edge,
  including row-reverse; reversing children does not reverse those edges.
• In columns, both physical keywords pack at the top. Grid uses its inline axis
  and ignores an irrelevant authored flex-direction.
• Normal ordering, auto margins, wrapping, gaps, box edges and overflow clipping
  keep their existing behavior. Non-formatting block/table properties remain
  inert. The same resolver serves validation and actual layout conversion.
• Forward flex and grid preserve explicit safe alignment. Physical safe
  values in reversed flex contexts produce a specific unsupported diagnostic
  until their overflow fallback can be represented correctly. RTL, vertical
  writing and unrelated unsupported alignment remain outside this increment.

The frozen contract
records the source/specification review, original failures and precise boundary.
This is not full CSS Box Alignment or bidi support.

Evidence and release status

The fourteen private adapter and nineteen public geometry/pixel/hit controls
were frozen before implementation. Actual old-source runs recorded nine and
fifteen assertion failures respectively; focused debug/release runs now pass
all controls and selected existing layout regressions. They are original
authored controls, not upstream WPT results.

Final-version full debug/release regressions, optional-chrome embedding,
dependency/tooling checks and all364 frozen JSPLAN outcomes pass. The complete
independently reviewed static selection reports319PASS/630FAIL/62UNSUPPORTED
of1011. Only the original left/right-002 column cases gain PASS, each with zero
different pixels against its original reference. All old317 passing and949
runnable cases and the first24 passes are preserved; the manually strengthened
ratchet protects319 passes. Five other initially targeted cases still fail real
pixel comparisons. Corpus, scorer, viewport and resource limits are unchanged.

The separate complete Window lane remains15/16 passing files and77/79 actual
final subtests; its two genuine flex-valid assertions remain failing. Neither
denominator includes authored controls. Normal packaged installation/updater,
all thirteen existing native helpers, the separate physical-layout native/CDP
proof and both frozen worker-control suites pass locally. Exact-source CI/site
and public delivery require separate verification receipts.
Consult the dated log
and published release receipts for their actual results. Local measurements alone
do not establish binary delivery.

Install and limitations

curl -fsSL https://mgbrowser.org/install.sh | bash

The installer selects the latest actually published release, verifies SHA-256
and installs without sudo. Checksums are not independent signatures. Existing
browser processes must restart to use an installed update.

Modern-web compatibility is poor. Google search to first result is not working.
Ordinary Playwright compatibility, full browser event-loop/testharness behavior
and React/Vue applications are not supported. Boa-backed inline and bounded
classic external scripting is enabled by default (--disable-scripts opts out);
ES modules, dynamic script loading and fetch/XHR remain unsupported. CSS, fonts,
images, tabs and resources remain bounded subsets. The modern style-declaration
bridge is not full CSSOM. Cookies are memory-only.
Scripted activation of empty anchors can be rejected by the existing default
navigation validator; the installed layout check uses ordinary text links.

Linux X11/XWayland is the GUI target. The restricted JavaScript worker is not
a sandbox for the browser as a whole: do not use this preview for banking,
sensitive authenticated browsing or arbitrary hostile websites. Existing worker
source/opcode/System-allocation/work/time/lifetime/wire and OS limits remain;
they are not whole-browser quotas or GC/RSS measurements. Fatal Boa roots may
require actual Context/worker teardown.

Project code, documentation and original artwork: Apache-2.0. Dependencies retain
their licenses in packaged THIRD_PARTY_LICENSES.txt. Previously published tags
and assets remain immutable.

Verified public delivery: 2026-10-23

Published from 7e13cca45c525921a5072a00eab658cf2782d4e9 after exact-commit Rust, JSPLAN, both WPT score lanes and site publication passed. The normal tagged release workflow also passed.

The advertised public installer passed fresh installation and reinstall, delivered version/build identity, worker/session and real Boa/CSSOM checks, desktop launcher and icons. A verified v0.9.14 binary successfully updated to v0.9.15 and passed a no-op recheck. Both frozen worker suites, all thirteen existing native/CDP helpers and the separate public-binary physical-layout pixel/click proof passed. Four actual native/CDP screenshots were visually inspected.

Archive: 8,097,280 bytes. SHA-256: 64ca33140748544abc94f4a9a92cc670bb5b320618b407555b6f72e5ccf5a08f. The published checksum matches and the archive fits the unchanged 8 MiB updater limit.

Separate verification receipts and remaining limitations. These checks do not establish broad web compatibility or complete the formal MVP.