Microsoft Edge 140 web platform release notes (Sep. 2025) (#3524)

* New beta web platform release notes

* Finalized relnotes content

* In-article TOC

* Fix md tagging

* Writer/Editor pass

* sdk expect dates

* New beta web platform release notes

* Writer/Editor pass, format

* toc entry

* linkfix

* Edit pass for new features

* OTs

* escape length

* Writer/Editor review pass

* New beta web platform release notes

* Sort features and clean them up

* More formatting

* cont'd

* webrtc audiolevel

* cont'd

* cont'd

* browser bound keys

* Done with most content

* toc

* add todo's for clarif

* see also todos

* links

* Revert "links"

This reverts commit e456df6.

* addressed todos

* nits

* link

* fix date

* cap'z JS

* New beta web platform release notes

* Add TOC entry

* In progress rewrite and formatting

* Done with content changes

* detailed content

* escape code in link text

* Remove local network access as it's not shipping in 140

* Writer/Editor pass

* linkfix

---------

Co-authored-by: captainbrosset <captainbrosset@users.noreply.github.com>
Co-authored-by: Michael S. Hoffman <v-mihoffman@microsoft.com>

Author: captainbrosset

microsoft-edge/toc.yml

@@ -30,6 +30,10 @@
           href: ./web-platform/release-notes/index.md
           displayName: what's new, announcements
 
+        - name: Microsoft Edge 140
+          href: ./web-platform/release-notes/140.md
+          displayName: Microsoft Edge 140 web platform release notes (Sep. 2025)  # page title
+
         - name: Microsoft Edge 139
           href: ./web-platform/release-notes/139.md
           displayName: Microsoft Edge 139 web platform release notes (Aug. 2025)  # page title

microsoft-edge/web-platform/release-notes/138.md

@@ -24,7 +24,6 @@ To stay up-to-date and get the latest web platform features, download a preview
     * [CSS environment variable for OS-level font scale](#css-environment-variable-for-os-level-font-scale)
     * [CSS `sibling-index()` and `sibling-count()` functions](#css-sibling-index-and-sibling-count-functions)
     * [Interpolation progress: CSS `progress()` function](#interpolation-progress-css-progress-function)
-    * [Nested view transitions](#nested-view-transitions)
   * [Web APIs](#web-apis)
     * [Prompt and Writing Assistance API developer previews](#prompt-and-writing-assistance-api-developer-previews)
     * [New `prefetchCache` and `prerenderCache` values for the `Clear-Site-Data` header](#new-prefetchcache-and-prerendercache-values-for-the-clear-site-data-header)
@@ -53,10 +52,7 @@ To stay up-to-date and get the latest web platform features, download a preview
 <!-- ====================================================================== -->
 ## Edge DevTools
 
-See [What's New in Microsoft Edge DevTools](../../devtools/whats-new/whats-new.md).
-<!-- todo: when it exists in Jun 2025, use instead:
 See [What's New in DevTools (Microsoft Edge 138)](../../devtools/whats-new/2025/06/devtools-138.md).
--->
 
 
 <!-- ====================================================================== -->
@@ -146,24 +142,6 @@ See also:
 * [[css-values] Proposal for a 'progress' function to calculate progress between two `<length>` values](https://github.com/w3c/csswg-drafts/issues/7268) on the CSS Working Group GitHub repo.
 
 
-<!-- ---------- -->
-###### Nested view transitions
-
-Nested view transitions allow view transitions to generate a nested pseudo-element tree rather than a flat pseudo-element tree, which allows certain view transitions to appear more like their original elements.
-
-Some CSS features rely on the relationship between elements in the DOM tree, such as:
-
-* Clipping from the `overflow`, `clip-path`, or `border-radius` properties.
-* 3D effects from the `transform`, `transform-style`, or `perspective` properties.
-* Masking and effects from the `opacity`, `mask-image`, or `filter` properties.
-
-The visual output of these effects depend on the DOM tree structure, and a view transition that flattens the DOM tree can cause these effects to not work as expected.
-
-See also:
-* [View Transition API](https://developer.mozilla.org/docs/Web/API/View_Transition_API) at MDN.
-* [Explainer: Nested View Transition Groups](https://github.com/WICG/view-transitions/blob/main/nested-explainer.md) on the WICG/view-transitions GitHub repo.
-
-
 <!-- ------------------------------ -->
 #### Web APIs
 

microsoft-edge/web-platform/release-notes/139.md

@@ -5,7 +5,7 @@ author: MSEdgeTeam
 ms.author: msedgedevrel
 ms.topic: conceptual
 ms.service: microsoft-edge
-ms.date: 6/26/2025
+ms.date: 06/26/2025
 ---
 # Microsoft Edge 139 web platform release notes (Aug. 2025)
 
@@ -20,7 +20,6 @@ To stay up-to-date and get the latest web platform features, download a preview
 * [Web platform features](#web-platform-features)
   * [CSS features](#css-features)
     * [CSS custom functions](#css-custom-functions)
-    * [CSS `caret-animation` property](#css-caret-animation-property)
     * [CSS `font-width` property](#css-font-width-property)
     * [Continue running transitions when switching to initial transition value](#continue-running-transitions-when-switching-to-initial-transition-value)
     * [CSS `corner-shape` property](#css-corner-shape-property)
@@ -99,20 +98,6 @@ See also:
 * [Defining Custom Functions](https://drafts.csswg.org/css-mixins-1/#defining-custom-functions) in the _CSS Functions and Mixins Module_ specification.
 
 
-<!-- ---------- -->
-###### CSS `caret-animation` property
-
-Microsoft Edge supports animating the `caret-color` CSS property.  However, when animated, the default blinking behavior of the caret interfered with the animation.
-
-The `caret-animation` property now supports two values:
-
-* `auto`: The default browser blinking behavior occurs.
-* `manual`: You control the caret animation.
-
-See also:
-* [Animation of the insertion caret: caret-animation](https://drafts.csswg.org/css-ui/#caret-animation) in _CSS Basic User Interface Module Level 4_.
-
-
 <!-- ---------- -->
 ###### CSS `font-width` property
 
@@ -517,7 +502,7 @@ The origins that are listed in the `scope_extensions` member must confirm that t
 <!-- ---------- -->
 ###### Acquisition Info API
 
-Expires on June 30, 2025.
+Expires on December 18, 2025.
 
 The Acquisition Info API supports third-party acquisition attribution for PWAs that were acquired through an app store or directly from the browser.