[31] [DFN[HTTP Client Hints]] は、[[内容折衝]]の一種です。

* 仕様書

[28] [[Internet Draft]] で規定されています。

[29] [CITE[Fetch Standard]] にも関係する規定があります。

* 機能

[FIG(short list)[ [21] 
- [CODE[Save-Data]]
]FIG]

* 実装

[26] [[解像度]]情報と [CODE[Save-Data]] は、 [[Blink]] が実装しています。

[27] [[Gecko]] は大反対はしていないものの積極的に実装しようともしておらず、
長年放置状態です。

[30] 利用例はほとんど見かけません。

[49] [CITE@en[Client hints or client lies? | Vivaldi Browser]], [TIME[2023-06-09T11:06:03.000Z]], [TIME[2023-06-09T11:56:24.361Z]] <https://vivaldi.com/blog/technology/client-hints-or-client-lies/>


[50] 
[CODE[User-Agent:]] と同じ歴史を辿る、当然そうなるよね。みんなわかってたよね。

* 歴史

[1] [CITE@en[draft-grigorik-http-client-hints-00 - HTTP Client Hints]]
( ([TIME[2013-11-03 11:29:59 +09:00]] 版))
<http://tools.ietf.org/html/draft-grigorik-http-client-hints-00>

[2] [CITE[igrigorik/http-client-hints · GitHub]]
( ([TIME[2013-11-10 01:08:25 +09:00]] 版))
<https://github.com/igrigorik/http-client-hints#client-hints-internet-draft>

[3] [CITE[''''''[''''''whatwg'''''']'''''' The src-N proposal]]
( ([TIME[2013-11-09 16:42:33 +09:00]] 版))
<http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2013-November/041380.html>

[4] [CITE@en[igrigorik/http-client-hints]] ([TIME[2014-10-24 06:38:59 +09:00]] 版) <https://github.com/igrigorik/http-client-hints>

[5] [CITE@en[HTTP Client Hints]]
( ([TIME[2014-09-09 17:40:13 +09:00]] 版))
<http://igrigorik.github.io/http-client-hints/>

[6] [CITE[''''''[''''''webkit-dev'''''']'''''' Client Hints]]
([TIME[2015-04-25 02:19:18 +09:00]] 版)
<https://lists.webkit.org/pipermail/webkit-dev/2015-April/027381.html>

[7] [CITE[''''''[''''''webkit-dev'''''']'''''' Client Hints]]
([TIME[2015-04-25 02:19:18 +09:00]] 版)
<https://lists.webkit.org/pipermail/webkit-dev/2015-April/027383.html>

[8] [CITE@en[igrigorik/http-client-hints]]
([TIME[2015-05-03 19:43:25 +09:00]] 版)
<https://github.com/igrigorik/http-client-hints>

[9] [CITE@en[HTTP Client Hints]]
([TIME[2015-03-25 07:21:49 +09:00]] 版)
<http://igrigorik.github.io/http-client-hints/>

[10] [CITE@en[935216 – (client-hints) Implement Client-Hints HTTP header]]
([TIME[2016-04-11 12:55:48 +09:00]] 版)
<https://bugzilla.mozilla.org/show_bug.cgi?id=935216>

[11] [CITE[Intent to (re-)implement - Client Hints - Google グループ]]
([TIME[2016-04-11 13:03:39 +09:00]] 版)
<https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/vOgv-TqefsA>

[12] [CITE[Intent to Ship: DPR, Width, and Viewport-Width client hints - Google グループ]]
([TIME[2016-04-11 13:06:38 +09:00]] 版)
<https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/vvX1vCQihDE>

[13] [CITE@en[http-client-hints/browser_implementation_considerations.md at browser_considerations · yoavweiss/http-client-hints]]
([TIME[2016-04-11 13:06:56 +09:00]] 版)
<https://github.com/yoavweiss/http-client-hints/blob/browser_considerations/browser_implementation_considerations.md>

[14] [CITE[HTTP Client Hints: DPR, Width, Viewport-Width - Chrome Platform Status]]
([TIME[2016-04-11 13:07:17 +09:00]] 版)
<https://www.chromestatus.com/feature/5504430086553600>

[15] [CITE[Automating resource selection with Client Hints | Web Updates - Google Developers]]
([TIME[2016-02-02 07:43:27 +09:00]] 版)
<https://developers.google.com/web/updates/2015/09/automating-resource-selection-with-client-hints>

[16] [CITE[Are we in favour of implementing the client hints header? - Google グループ]]
([TIME[2016-04-11 13:20:36 +09:00]] 版)
<https://groups.google.com/forum/#!msg/mozilla.dev.platform/05fJvmuG35c/UaNE8yrUBAAJ>

[17] [CITE@en[Support HTTP Client Hints · whatwg/fetch@404dc3a]]
([TIME[2016-04-12 17:49:59 +09:00]] 版)
<https://github.com/whatwg/fetch/commit/404dc3acfddb5e9870fdee333302f80ecff661dd>

[18] [CITE@en[Issues · httpwg/http-extensions]]
([TIME[2017-02-18 21:26:13 +09:00]])
<https://github.com/httpwg/http-extensions/labels/client-hints>

[19] [CITE@en[Stop lowercasing header names]]
([[annevk]]著, [TIME[2017-02-22 20:01:22 +09:00]])
<https://github.com/whatwg/fetch/commit/5869c43a27fff06c6dfc228fe1288018f7f2168d>

[20] [CITE[Are we in favour of implementing the client hints header? - Google グループ]]
([TIME[2017-03-21 00:29:26 +09:00]])
<https://groups.google.com/forum/#!msg/mozilla.dev.platform/05fJvmuG35c/UaNE8yrUBAAJ>

[22] [CITE[Automatic image scale and resolution with Client Hints | Cloudinary Blog]]
([TIME[2017-03-21 00:01:02 +09:00]])
<http://cloudinary.com/blog/automatic_responsive_images_with_client_hints>

;; [23] 紹介しているこのページ自体は使っていない。

[24] [CITE@en[Define `Accept-CH` more precisely · Issue #155 · httpwg/http-extensions]]
([TIME[2017-03-21 00:32:10 +09:00]])
<https://github.com/httpwg/http-extensions/issues/155>

[25] [CITE@en[Define more precisely which CH headers are sent by default · Issue #156 · httpwg/http-extensions]]
([TIME[2017-03-21 00:32:36 +09:00]])
<https://github.com/httpwg/http-extensions/issues/156>

[32] [CITE[HTTP Client Hints: DPR, Width, Viewport-Width - Chrome Platform Status]]
([TIME[2017-03-21 00:37:12 +09:00]])
<https://www.chromestatus.com/feature/5504430086553600>

[33] [CITE@en-US[Content negotiation - HTTP | MDN]]
([TIME[2017-02-20 12:30:11 +09:00]])
<https://developer.mozilla.org/en-US/docs/Web/HTTP/Content_negotiation#The_Accept-CH_header>

[34] [CITE['''['''webkit-dev''']''' Client Hints]]
([TIME[2015-04-25 02:19:18 +09:00]])
<https://lists.webkit.org/pipermail/webkit-dev/2015-April/027381.html>

[35] [CITE['''['''webkit-dev''']''' Client Hints]]
([TIME[2015-04-29 00:42:46 +09:00]])
<https://lists.webkit.org/pipermail/webkit-dev/2015-April/027390.html>

[36] [CITE@en[535979 - client-hints: no Width header for picture/source with viewport change across breakpoint - chromium - Monorail]]
([TIME[2017-03-21 00:42:25 +09:00]])
<https://bugs.chromium.org/p/chromium/issues/detail?id=535979>

[37] [CITE@en[New in Chrome 62  |  Web  |  Google Developers]]
([TIME[2017-10-18 04:02:40 +09:00]])
<https://developers.google.com/web/updates/2017/10/nic62>

[38] [CITE@en[`Accept-CH` header is weird · Issue #206 · w3ctag/design-reviews]]
([TIME[2017-12-08 18:53:44 +09:00]])
<https://github.com/w3ctag/design-reviews/issues/206>

[39] [CITE@en[RFP: Client Hints · Issue #79 · mozilla/standards-positions]]
([TIME[2018-04-03 22:14:42 +09:00]])
<https://github.com/mozilla/standards-positions/issues/79>

[40] [CITE@en[Adjust casing of client hints]]
([[annevk]]著, [TIME[2018-04-18 00:37:17 +09:00]])
<https://github.com/whatwg/fetch/commit/fd8ee5c9021c4f0449f1a507696be92516221cce>

[41] [CITE@en[Casing of client headers is maybe not accurate · Issue #475 · whatwg/fetch]]
([TIME[2018-04-18 13:34:42 +09:00]])
<https://github.com/whatwg/fetch/issues/475>

[42] [CITE@en[Editorial: client hints are sometimes strings; should always be byte sequences · Issue #561 · whatwg/fetch]]
([TIME[2018-04-18 13:36:33 +09:00]])
<https://github.com/whatwg/fetch/issues/561>

[43] [CITE@en[Adjust casing of client hints by annevk · Pull Request #704 · whatwg/fetch]]
([TIME[2018-04-18 13:38:27 +09:00]])
<https://github.com/whatwg/fetch/pull/704>

[44] [CITE@en[Listing headers safe only for certain values is a bad idea · Issue #313 · whatwg/fetch]]
([TIME[2018-08-22 19:10:48 +09:00]])
<https://github.com/whatwg/fetch/issues/313>

[45] [CITE@en[Remove Client Hints]]
([[annevk]]著, [TIME[2019-03-23 18:25:39 +09:00]])
<https://github.com/whatwg/fetch/commit/6a644c676558edc7e80548e25c6f85bf0143f395>

[46] [CITE@en[Does Client Hints have multi vendor support? · Issue #867 · whatwg/fetch]]
([TIME[2019-07-24 20:42:22 +09:00]])
<https://github.com/whatwg/fetch/issues/867>

[47] [CITE@en[Remove Client Hints by annevk · Pull Request #884 · whatwg/fetch]]
([TIME[2019-07-24 20:42:49 +09:00]])
<https://github.com/whatwg/fetch/pull/884>

[48] [CITE@en[Client Hints Infrastructure]]
([TIME[2020-07-07 17:16:18 +09:00]])
<https://wicg.github.io/client-hints-infrastructure/>

[51] [CITE@en[Client hints or client lies? | Vivaldi Browser]], [TIME[2024-07-29T06:42:10.000Z]] <https://vivaldi.com/blog/technology/client-hints-or-client-lies/>