Intent to prototype: CSS text-autospace property

[Ting-Yu Lin 林庭宇]

Summary: text-autospace automatically creates small spacing between characters of different writing systems (e.g. between Latin scripts and Chinese or Japanese scripts), enhancing readability in multilingual content.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1869577 (The implementation will be tracked in the dependency bugs.)

Specification: https://drafts.csswg.org/css-text-4/#propdef-text-autospace

Standards Body: W3C CSSWG

Platform coverage: All platforms.

Preference: layout.css.text-autospace.enabled

DevTools bug: N/A

Link to standards-positions discussion: https://github.com/mozilla/standards-positions/issues/903 (Note: text-autospace a longhand of the text-spacing shorthand.)

Other browsers:

• Blink: Shipping (expected in version 140). See the intent to ship in blink-dev: https://groups.google.com/a/chromium.org/g/blink-dev/c/gwRvkPJ5pws/m/F3r-VeGoBAAJ and Chrome Platform Status: https://chromestatus.com/feature/5202578236768256?gate=5117712266690560
• WebKit: Safari shipped in 18.4. https://developer.apple.com/documentation/safari-release-notes/safari-18_4-release-notes#CSS. 

Interop & webcompat analysis:

Both blink and wekbit support a subset of the values in the spec, i.e. "normal" and "no-autospace". They shipped with the initial value "no-autospace", while the spec's initial value is "normal". See the spec issue on revisiting the initial value: https://github.com/w3c/csswg-drafts/issues/12386

web-platform-tests: https://wpt.fyi/results/css/css-text?label=master&label=experimental&aligned&q=text-autospace

Thanks,
Ting-Yu