From af0a6bfdde75a7472bd172d6d3e1e5588a5234a3 Mon Sep 17 00:00:00 2001
From: Hugh Nimmo-Smith <hughns@element.io>
Date: Fri, 31 Oct 2025 11:52:42 +0000
Subject: [PATCH] Update unstable prefixes including on QR code

---
 proposals/4108-oidc-qr-login.md              |  69 +++++++++++--------
 proposals/images/4108-qr-mode04-unstable.png | Bin 0 -> 813 bytes
 2 files changed, 42 insertions(+), 27 deletions(-)
 create mode 100644 proposals/images/4108-qr-mode04-unstable.png

diff --git a/proposals/4108-oidc-qr-login.md b/proposals/4108-oidc-qr-login.md
index c88d71bc2..78e906786 100644
--- a/proposals/4108-oidc-qr-login.md
+++ b/proposals/4108-oidc-qr-login.md
@@ -439,7 +439,8 @@ encoded) at rendezvous session ID `e8da6355-550b-4a32-a193-1619d9830668` on home
 (Whitespace is for readability only)
 
 ```
-4D 41 54 52 49 58 02  03
+4D 41 54 52 49 58
+02 03
 d8 86 68 6a b2 19 7b 78 0e 30 0a 9d 4a 21 47 48 07 00 d7 92 9f 39 ab 31 b9 e5 14 37 02 48 ed 6b
 00 24
 65 38 64 61 36 33 35 35 2D 35 35 30 62 2D 34 61 33 32 2D 61 31 39 33 2D 31 36 31 39 64 39 38 33 30 36 36 38
@@ -451,7 +452,8 @@ Which looks as follows as a QR with error correction level Q:
 <!--
 Generated with:
 
-nix-shell -p qrencode --run 'echo "4D 41 54 52 49 58 02  03
+nix-shell -p qrencode --run 'echo "4D 41 54 52 49 58
+02 03
 d8 86 68 6a b2 19 7b 78 0e 30 0a 9d 4a 21 47 48 07 00 d7 92 9f 39 ab 31 b9 e5 14 37 02 48 ed 6b
 00 24
 65 38 64 61 36 33 35 35 2D 35 35 30 62 2D 34 61 33 32 2D 61 31 39 33 2D 31 36 31 39 64 39 38 33 30 36 36 38
@@ -466,7 +468,8 @@ A full example for an existing device using ephemeral public key `2IZoarIZe3gOMA
 encoded), at rendezvous session ID `e8da6355-550b-4a32-a193-1619d9830668` on homeserver`matrix.org` is as follows: (Whitespace is for readability only)
 
 ```
-4D 41 54 52 49 58 02  04
+4D 41 54 52 49 58
+02 04
 d8 86 68 6a b2 19 7b 78 0e 30 0a 9d 4a 21 47 48 07 00 d7 92 9f 39 ab 31 b9 e5 14 37 02 48 ed 6b
 00 24
 65 38 64 61 36 33 35 35 2D 35 35 30 62 2D 34 61 33 32 2D 61 31 39 33 2D 31 36 31 39 64 39 38 33 30 36 36 38
@@ -478,7 +481,8 @@ Which looks as follows as a QR with error correction level Q:
 <!--
 Generated with:
 
-nix-shell -p qrencode --run 'echo "4D 41 54 52 49 58 02  04
+nix-shell -p qrencode --run 'echo "4D 41 54 52 49 58
+02 04
 d8 86 68 6a b2 19 7b 78 0e 30 0a 9d 4a 21 47 48 07 00 d7 92 9f 39 ab 31 b9 e5 14 37 02 48 ed 6b
 00 24
 65 38 64 61 36 33 35 35 2D 35 35 30 62 2D 34 61 33 32 2D 61 31 39 33 2D 31 36 31 39 64 39 38 33 30 36 36 38
@@ -1681,50 +1685,61 @@ Recommendations to mitigate this are:
 
 ## Unstable prefix
 
+n.b. the [2024 version](https://github.com/matrix-org/matrix-spec-proposals/blob/87f8317a902cd7bc5c2d2d225f71021b3a509e2d/proposals/4108-oidc-qr-login.md#unstable-prefix)
+of this proposal used a different set of unstable prefixes.
+
 ### Rendezvous API prefix
 
 While this feature is in development the new API endpoints should be exposed using the following unstable prefix:
 
-- `/_matrix/client/unstable/org.matrix.msc4108/rendezvous` instead of `/_matrix/client/v1/rendezvous`
+- `/_matrix/client/unstable/io.element.msc4108/rendezvous` instead of `/_matrix/client/v1/rendezvous`
 
-Additionally, the feature is to be advertised as unstable feature in the GET /_matrix/client/versions response, with the
-key org.matrix.msc4108 set to true. So, the response could look then as following:
+Additionally, the feature is to be advertised as unstable feature in the `GET /_matrix/client/versions` response, with the
+key `io.element.msc4108` set to true. So, the response could look then as following:
 
 ```json
 {
     "versions": ["..."],
     "unstable_features": {
-        "org.matrix.msc4108": true
+        "io.element.msc4108": true
     }
 }
 ```
 
 ### Unstable QR code format
 
-It would be helpful to make it clear that the QR code format is unstable, but need some guidance on what would be the
-best way to do this. See notes above about QR format/versioning.
-
-### M_CONCURRENT_WRITE errcode
+The unstable value of `IO_ELEMENT_MSC4108` should be used instead of `MATRIX` in the QR code.
 
-Furthermore, where a new `errcode` is being introduced the existing `M_UNKNOWN` code should be used instead, with the new
-code placed in a `org.matrix.msc4108.errcode` field instead. For example, instead of:
+A full example for an existing device using ephemeral public key `2IZoarIZe3gOMAqdSiFHSAcA15KfOasxueUUNwJI7Ws` (base64
+encoded), at rendezvous session ID `e8da6355-550b-4a32-a193-1619d9830668` on homeserver `matrix.org` is as follows: (Whitespace is for readability only)
 
-```json
-{
-    "errcode": "M_CONCURRENT_WRITE",
-    "error": "Data was modified"
-}
 ```
+49 4F 5F 45 4C 45 4D 45 4E 54 5F 4D 53 43 34 31 30 38
+02 04
+d8 86 68 6a b2 19 7b 78 0e 30 0a 9d 4a 21 47 48 07 00 d7 92 9f 39 ab 31 b9 e5 14 37 02 48 ed 6b
+00 24
+65 38 64 61 36 33 35 35 2D 35 35 30 62 2D 34 61 33 32 2D 61 31 39 33 2D 31 36 31 39 64 39 38 33 30 36 36 38
+00 0A
+6d 61 74 72 69 78 2e 6f 72 67
+```
+
+Which looks as follows as a QR with error correction level Q:
+<!--
+Generated with:
+
+nix-shell -p qrencode --run 'echo "49 4F 5F 45 4C 45 4D 45 4E 54 5F 4D 53 43 34 31 30 38
+02 04
+d8 86 68 6a b2 19 7b 78 0e 30 0a 9d 4a 21 47 48 07 00 d7 92 9f 39 ab 31 b9 e5 14 37 02 48 ed 6b
+00 24
+65 38 64 61 36 33 35 35 2D 35 35 30 62 2D 34 61 33 32 2D 61 31 39 33 2D 31 36 31 39 64 39 38 33 30 36 36 38
+00 0A
+6d 61 74 72 69 78 2e 6f 72 67" | xxd -r -p | qrencode -8 -l Q -t PNG -o ./proposals/images/4108-qr-mode04-unstable.png'
+-->
+![Example QR for mode 0x04](images/4108-qr-mode04-unstable.png)
 
-The server should send:
+### M_CONCURRENT_WRITE errcode
 
-```json
-{
-    "errcode": "M_UNKNOWN",
-    "org.matrix.msc4108.errcode": "M_CONCURRENT_WRITE",
-    "error": "Data was modified"
-}
-```
+The unstable value of `IO_ELEMENT_MSC4108_CONCURRENT_WRITE` should be used instead of `M_CONCURRENT_WRITE`.
 
 ## Dependencies
 
diff --git a/proposals/images/4108-qr-mode04-unstable.png b/proposals/images/4108-qr-mode04-unstable.png
new file mode 100644
index 0000000000000000000000000000000000000000..5ab3939a8a93e8882700e12838a7cf12533936b7
GIT binary patch
literal 813
zcmV+|1JeA7P)<h;3K|Lk000e1NJLTq00651006520{{R3BPRY@00006P)t-s00030
z|No`gpWOfe00MMUPE-H?$hF_c00009a7bBm000XT000XT0n*)m`~Uy~zez+vR7i>C
zmpzW-Fbsuhs8APQK!C2HPFJ!o;GYZFS5l{I2+#$r&V^v^lQWswVvD8Q2?8Ve3^3*s
z`N$Ce^F_ZKA4DUomCYEbi?#&n<hXF1W9lQ3&kNxWh#Utqa^BB6pLx-0jrgf2c<_01
zb`5#Q{ik^H`EW!!Gh2R!xehvwA<fZrC$8Vg3vkmrnxFSy$MF9cuM$#^*rE2(?mq<~
zz?Vzpcn_6yoix2DjdEOq+B9@BeNdNI>zP+M=9rLHVN?*x2OmuL0JGgRZ;l3MFS08u
zet<(AW1Ts#K^>X~&8r+AE_2KWrAaG}_)5JTqv(2u#&sfFPU_Cu$#Dr>B4oCgGvsM<
z=m|MSuxJm>i??eu1HH>fhWWG`<;xpFerKH=&2oG=ID|dCd3iIQxc{y}8Aj|96V7Ts
z@frP8dpSmPzo?R{(COtf3gH1hJS2zAC}$Wj@2qw?#%U80jfn^t*LOF_@IlbYE*dUX
z;V~EpMUF3m-Y}RnMtjTljxEF<^$VLpY_t^m()4l+od~Cmt5#^QrR6HdXv#&mso1xu
zY4UHqWw^C9)$UX~5=CRtXGBYIVT(lfsP^WX7zlQiWB5~tW7h_Thb%98&om)+YHyuX
z@pKH&dxXoqDGW|+gkMnC=NLrzg252=7^<gT9Adu>Plh?9m#;I*=N5baDr6bH(3gz1
zu7gJ*w|T;H%$x>-*fjZ8MB~@8Aj3y1I#o_}xx8Vfoq3mI*d#pWwkvcwdV<RX+`0;G
zXSX)wsSEZ2KH8#zv1~}gfNA)6l?b=pr+GH^Q(l^PKEd}EhM88I*m%15@j(ejU`(OX
zwlF*<nCTzjVCG=&EX_psuKfrPUX_n?A75*W7(*nu_zSLyvGxpOM|QmEya(tFw=lCD
rL+=(_!y%}-xc^?A1z7eM>o?#(a#~)uYll7800000NkvXXu0mjf4_I}f

literal 0
HcmV?d00001