Thanks Mason! LGTM1 pending those tests. On Tuesday, September 29, 2026 at 7:47:40 AM UTC-7 Mason Freed wrote:
> On Monday, September 28, 2026 at 11:32:35 AM UTC-7 Dan Clark wrote: > > *> Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* > > *> > Yes> > https://wpt.fyi/results/css/css-anchor-position?label=master&label=experimental&aligned&q=position-visibility > > <https://wpt.fyi/results/css/css-anchor-position?label=master&label=experimental&aligned&q=position-visibility>* > > The only of these tests I saw covering anchor-valid is this one: > https://wpt.fyi/results/css/css-anchor-position/position-visibility-anchor-valid.tentative.html > > <http://Is%20this%20feature%20fully%20tested%20by%20web-platform-tests?%20Yes%20https://wpt.fyi/results/css/css-anchor-position?label=master&label=experimental&aligned&q=position-visibility> > . > > Maybe not too many tests are needed, but does this fully cover the > behavior called out in the summary? "[The new version is] better defined > to be clear that only the default anchor matters , resolving a lot of > ambiguity"? > > > Sorry, I should have added to that response that my CL to implement the > feature <https://crrev.com/c/8453827> adds more testing. > > > E.g. the test shows that this is hidden: > <div id="target2" class="target" style="top: anchor(--does-not-exist > bottom);">target2</div> > > But it'd be nice to include a case where position-anchor is unset but > anchor() refers to an anchor name that actually does exist: > <div id="target3" class="target" style="top: anchor(--a1 > bottom);">target2</div> > > > I believe this is "Case 7" from the > new position-visibility-anchor-valid-001.html test. > > > And maybe a similar set of checks with anchor-size(). > > > This is indeed missing. I'll land another CL to add test cases for > anchor-size like this - thanks for the suggestion. > > > Another case that seems important to have is an element that has a valid > default anchor, but another anchor it depends on doesn't resolve. If I'm > understanding correctly that would have resulted in the element being > hidden in the original proposal > <https://github.com/w3c/csswg-drafts/issues/7758#issuecomment-1965540529>, > but in the current proposal the element would be shown, since only the > default anchor matters. > > > Also a good (missing) suggestion. I'll add it! > > Thanks, > Mason > > > Thanks, > Dan > > On Friday, September 25, 2026 at 2:53:52 PM UTC-7 Chris Harrelson wrote: > > Thanks! LGTM1 > > On Fri, Sep 25, 2026 at 1:24 PM Mason Freed <[email protected]> wrote: > > > On Fri, Sep 25, 2026 at 9:36 AM Chris Harrelson <[email protected]> > wrote: > > My thought is that, because Firefox doesn't ship anchor-valid yet, it > seems helpful to just file the positions request to encourage interop on > this subfeature. Especially since this feature came a bit later than the > others due to additional spec discussion to align on its semantics, so > perhaps it fell through the cracks a bit (like it did in Chromium until > just now). > > > Fair point. Done: > https://github.com/mozilla/standards-positions/issues/1457 > > Thanks, > Mason > > > > On Fri, Sep 25, 2026 at 9:30 AM Mason Freed <[email protected]> wrote: > > > On Thu, Sep 24, 2026 at 5:07 PM Chris Harrelson <[email protected]> > wrote: > > Could you file a Mozilla standards request? > > > So there's already a (positive) standards position for anchor positioning > as a whole: https://github.com/mozilla/standards-positions/issues/794. Do > you think `anchor-valid` by itself deserves its own standards position? I > think perhaps we should think about #794 as a position on the entire > feature, including all sub-features. If you disagree, of course I'm happy > to file a new one. > > Thanks, > Mason > > > > On Wed, Sep 23, 2026 at 3:56 PM Mason Freed <[email protected]> wrote: > > *Contact emails* > [email protected] > > *Explainer* > *No information provided* > > *Specification* > https://drafts.csswg.org/css-anchor-position-1/#position-visibility > > *Summary* > The `anchors-valid` value was implemented as part of > https://crbug.com/329703412 but subsequently reverted, due to spec > questions about the exact definition of the value. Since that time, the > value has been renamed to `anchor-valid` (see > https://chromestatus.com/feature/5136123851571200) and also better > defined to be clear that only the default anchor matters, resolving a lot > of ambiguity, and making this value shippable. > > *Blink component* > Blink>CSS > <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ECSS%22> > > *Web Feature ID* > anchor-positioning <https://webstatus.dev/features/anchor-positioning> > > *Motivation* > *No information provided* > > *Initial public proposal* > *No information provided* > > *Search tags* > position-visibility > <https://chromestatus.com/features#tags:position-visibility>, anchor-valid > <https://chromestatus.com/features#tags:anchor-valid>, anchors-valid > <https://chromestatus.com/features#tags:anchors-valid> > > *TAG review* > *No information provided* > > *TAG review status* > Not applicable > > *Goals for experimentation* > None > > *Risks* > > > *Interoperability and Compatibility* > This is new support for a value for `position-visibility` so it should not > create compat risks. Shipping this value will improve interop - WebKit > already ships it. > > *Gecko*: No signal > > *WebKit*: Shipped/Shipping > > *Web developers*: No signals > > *Other signals*: > > *WebView application risks* > > Does this intent deprecate or change behavior of existing APIs, such that > it has potentially high risk for Android WebView-based applications? > *No information provided* > > > *Debuggability* > *No information provided* > > *Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)?* > Yes > > *Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* > Yes > > https://wpt.fyi/results/css/css-anchor-position?label=master&label=experimental&aligned&q=position-visibility > > *Flag name on about://flags* > *No information provided* > > *Finch feature name* > CSSPositionVisibilityAnchorValid > > *Rollout plan* > Will ship enabled for all users > > *Requires code in //chrome?* > False > > *Tracking bug* > https://crbug.com/333421963 > > *Estimated milestones* > Shipping on desktop157DevTrial on desktop157Shipping on Android157DevTrial > on Android157Shipping on WebView123 > > *Anticipated spec changes* > > Open questions about a feature may be a source of future web compat or > interop issues. Please list open issues (e.g. links to known github issues > in the project for the feature specification) whose resolution may > introduce web compat/interop risk (e.g., changing to naming or structure of > the API in a non-backward-compatible way). > *No information provided* > > *Link to entry on the Chrome Platform Status* > https://chromestatus.com/feature/5136856479039488?gate=5692419038380032 > > This intent message was generated by Chrome Platform Status > <https://chromestatus.com/>. > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDgQ_W7-2FxYgaXc4-r7-vuaq1rexfHn4w4YEEW-Cz0%2BSA%40mail.gmail.com > > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDgQ_W7-2FxYgaXc4-r7-vuaq1rexfHn4w4YEEW-Cz0%2BSA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDjXTYLG_kz2nEhK19VGFOvQQZcds38-6jzoDk7ZeNBUQg%40mail.gmail.com > > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDjXTYLG_kz2nEhK19VGFOvQQZcds38-6jzoDk7ZeNBUQg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDgCzuuVhhsikDnHq_iZu2XkXuK1cJ6dT23134Qg4WKV0w%40mail.gmail.com > > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDgCzuuVhhsikDnHq_iZu2XkXuK1cJ6dT23134Qg4WKV0w%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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