Return a content-encoding header for resource timing and more

fetch.bs

@@ -370,6 +370,8 @@ following <a for=struct>items</a>: [[RESOURCE-TIMING]] [[NAVIGATION-TIMING]]
  <dd>A number.
  <dt><dfn export for="response body info">content type</dfn> (default the empty string)
  <dd>An <a for=/>ASCII string</a>.
+ <dt><dfn export for="response body info">content encoding</dfn> (default the empty string)
+ <dd>An <a for=/>ASCII string</a>.
 </dl>
 
 <div algorithm>
@@ -1176,6 +1178,7 @@ is a <a>byte-case-insensitive</a> match for one of
    <li>`<a http-header><code>Access-Control-Request-Headers</code></a>`
    <li>`<a http-header><code>Access-Control-Request-Method</code></a>`
    <li>`<code>Connection</code>`
+   <li>`<code>Content-Encoding</code>`
    <li>`<code>Content-Length</code>`
    <li>`<code>Cookie</code>`
    <li>`<code>Cookie2</code>`
@@ -3946,6 +3949,40 @@ Content-Type:
 </div>
 </div>
 
+<h3 id=content-encoding>`<code>Content-Encoding</code>` header</h3>
+
+<p>The `<code>Content-Encoding</code>` header is largely defined in HTTP. Its processing model is
+defined here as the model defined in HTTP is not compatible with web content. [[HTTP]]
+
+<div algorithm>
+<p>To <dfn export for="header list" lt="extract an encoding type|extracting an encoding type">
+extract an encoding type</dfn> from a <a for=/>header list</a> <var>headers</var>, run these steps:
+
+<ol>
+ <li><p>Let <var>values</var> be the result of
+ <a for="header list">getting, decoding, and splitting</a> `<code>Content-Encoding</code>` from
+ <var>headers</var>.
+
+ <li><p>If <var>values</var> is null, then return null.
+
+ <li><p>Let <var>candidateValue</var> be null.
+
+ <li>
+  <p><a for=list>For each</a> <var>value</var> of <var>values</var>:
+
+  <ol>
+   <li><p>If <var>candidateValue</var> is null, then set <var>candidateValue</var> to
+   <var>value</var>.
+
+   <li><p>Otherwise, if <var>value</var> is not <var>candidateValue</var>, return failure.
+  </ol>
+
+ <li><p>If <var>candidateValue</var> is the empty string or has a <a for=/>code point</a> that is
+ not an <a for=/>ASCII digit</a>, then return null.
+
+ <li><p>Return <var>candidateValue</var>, interpreted as a string.
+</ol>
+</div>
 
 <h3 id=x-content-type-options-header>`<code>X-Content-Type-Options</code>` header</h3>
 
@@ -5004,6 +5041,13 @@ steps:
 
      <li><p>Let <var>type</var> be <var>blob</var>'s {{Blob/type}}.
 
+     <li><p>Let <var>accept-coding</var> be the result of <a for="header list">getting</a>
+       `<code>Accept-Encoding</code>` from <var>request</var>'s <a for=request>header list</a>.
+        If <var>accept-encoding</var> is not null and the server selects one of the encoding options,
+        let <var>coding</var> be the selected encoding option; otherwise, i.e., no encoding is used,
+        let <var>coding</var> be <a href=https://httpwg.org/specs/rfc9110.html#field.accept-encoding>
+        <code>"identity"</code></a>.
+
      <li>
       <p>If <var>request</var>'s <a for=request>header list</a>
       <a for="header list">does not contain</a> `<code>Range</code>`:
@@ -5019,7 +5063,9 @@ steps:
 
        <li><p>Set <var>response</var>'s <a for=response>header list</a> to «
        (`<code>Content-Length</code>`, <var>serializedFullLength</var>),
-       (`<code>Content-Type</code>`, <var>type</var>) ».
+       (`<code>Content-Type</code>`, <var>type</var>),
+       (`<code>Content-Encoding</code>`, <var>coding</var>) ».
+
       </ol>
 
      <li>
@@ -5088,7 +5134,8 @@ steps:
        <li><p>Set <var>response</var>'s <a for=response>header list</a> to «
        (`<code>Content-Length</code>`, <var>serializedSlicedLength</var>),
        (`<code>Content-Type</code>`, <var>type</var>), (`<code>Content-Range</code>`,
-       <var>contentRange</var>) ».
+       <var>contentRange</var>), (`<code>Content-Encoding</code>`, <var>coding</var>) ».
+
       </ol>
 
      <li><p>Return <var>response</var>.
@@ -5105,10 +5152,19 @@ steps:
      <li><p>Let <var>mimeType</var> be <var>dataURLStruct</var>'s
      <a for="data: URL struct">MIME type</a>, <a lt="serialize a MIME type to bytes">serialized</a>.
 
+     <li><p>Let <var>accept-coding</var> be the result of <a for="header list">getting</a>
+       `<code>Accept-Encoding</code>` from <var>request</var>'s <a for=request>header list</a>.
+        If <var>accept-encoding</var> is not null and the server selects one of the encoding options,
+        let <var>coding</var> be the selected encoding option; otherwise, i.e., no encoding is used,
+        let <var>coding</var> be <a href=https://httpwg.org/specs/rfc9110.html#field.accept-encoding>
+        <code>"identity"</code></a>.
+
      <li><p>Return a new <a for=/>response</a> whose <a for=response>status message</a> is
      `<code>OK</code>`, <a for=response>header list</a> is « (`<code>Content-Type</code>`,
-     <var>mimeType</var>) », and <a for=response>body</a> is <var>dataURLStruct</var>'s
-     <a for="data: URL struct">body</a> <a for="byte sequence">as a body</a>.
+     <var>mimeType</var>), (`<code>Content-Encoding</code>`, <var>coding</var>) », and
+     <a for=response>body</a> is <var>dataURLStruct</var>'s <a for="data: URL struct">
+     body</a> <a for="byte sequence">as a body</a>.
+
     </ol>
 
    <dt>"<code>file</code>"
@@ -9127,6 +9183,7 @@ Gavin Carothers,
 Glenn Maynard,
 Graham Klyne,
 Gregory Terzian,
+Guohui Deng(邓国辉)<!-- guohuideng2024; GitHub -->,
 Hal Lockhart,
 Hallvord R. M. Steen,
 Harris Hancock,