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<p>Hi there WebKit folks,</p>
<p>I'm writing to request a position on some recent API updates to
the User-Agent Client Hints API.</p>
<p>There's a blink-dev I2P on the topic at [1], but I'll repeat the
updates here:</p>
<p><b style="color: rgba(0, 0, 0, 0.87); font-size: 14px;
font-style: normal; font-variant-ligatures: normal;
font-variant-caps: normal; letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform: none; white-space:
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration-thickness: initial; text-decoration-style:
initial; text-decoration-color: initial; font-weight: normal;">
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><b
style="-webkit-tap-highlight-color: transparent;
font-weight: normal;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">1. Sec-CH-UA-Bitness: adds a new high-entropy hint to expose the OS bitness, which may be combined with Sec-CH-UA-Arch to provide optimized binaries for download, for example.</span></b></p>
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><b
style="-webkit-tap-highlight-color: transparent;
font-weight: normal;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Spec PR: <a class="moz-txt-link-freetext" href="https://github.com/WICG/ua-client-hints/pull/210">https://github.com/WICG/ua-client-hints/pull/210</a>. In the linked issue Maciej mentioned[2] that were Apple to implement this, it may just send the empty string or a fixed value (which are valid values, per spec).
</span></b></p>
<b style="-webkit-tap-highlight-color: transparent; font-weight:
normal;"><br style="-webkit-tap-highlight-color: transparent;">
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">2. Make Sec-CH-UA-Platform a low-entropy hint: OS is passively observable at the TCP level anyways, so we plan to change this to be low-entropy and send as a default header (similar to Sec-CH-UA and Sec-CH-UA-Mobile).</span></p>
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Spec PR: <a class="moz-txt-link-freetext" href="https://github.com/WICG/ua-client-hints/pull/221">https://github.com/WICG/ua-client-hints/pull/221</a>
</span></p>
<br style="-webkit-tap-highlight-color: transparent;">
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">3. Include low-entropy hints by default in UADataValues (returned by getHighEntropyValues()). If a hint moves from high to low-entropy, this future proofs any code relying on it.</span></p>
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Spec PR: <a class="moz-txt-link-freetext" href="https://github.com/WICG/ua-client-hints/pull/226">https://github.com/WICG/ua-client-hints/pull/226</a></span></p>
<br style="-webkit-tap-highlight-color: transparent;">
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">4. Add a toJSON method to NavigatorUAData’s IDL. Technically a bugfix, but it is an API change (instead of returning {}, </span><span style="font-size: 10pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">JSON.stringify(navigator.userAgentData)) will now be useful</span><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">)</span></p>
<p dir="ltr" style="-webkit-tap-highlight-color: transparent;
line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 10.5pt; color: rgb(0, 0, 0); background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Spec PR: <a class="moz-txt-link-freetext" href="https://github.com/WICG/ua-client-hints/pull/228">https://github.com/WICG/ua-client-hints/pull/228</a>
</span></p>
</b></b></p>
<p>(For context, Maciej provided a review previously in
<a class="moz-txt-link-freetext" href="https://lists.webkit.org/pipermail/webkit-dev/2020-November/031571.html">https://lists.webkit.org/pipermail/webkit-dev/2020-November/031571.html</a>
and filed a lot of great issues. 2 remain open: issues 151 and
148)<br>
</p>
<p>[1]
<a class="moz-txt-link-rfc2396E" href="https://groups.google.com/a/chromium.org/g/blink-dev/c/dafizBGwWMw/m/72l-1zm6AAAJ"><https://groups.google.com/a/chromium.org/g/blink-dev/c/dafizBGwWMw/m/72l-1zm6AAAJ></a>
<br>
[2]
<a class="moz-txt-link-rfc2396E" href="https://github.com/WICG/ua-client-hints/issues/105#issuecomment-626904363"><https://github.com/WICG/ua-client-hints/issues/105#issuecomment-626904363></a></p>
<p>thanks,<br>
Mike<br>
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