Mentions shouldn't follow permalink_prefix

[gabrc52]

Steps to reproduce

1. Set permalink_prefix in config.json to the URL where your Element webapp is hosted.
2. Mention someone in a room

Outcome

What did you expect?

Inline mentions should be Matrix URIs (i.e. matrix.to or matrix://) according to the spec

What happened instead?

The inline mention followed the URL format in permalink_prefix, which is problematic for several reasons:

Other clients (such as Element-Android or other Element-Web instances) render these mentions as links instead of proper pilled mentions. Most users on federated rooms are on a different homeserver and use a different config.json if not a different Matrix client.

In addition, config.md says the following about permalink_prefix:

permalink_prefix: An optional URL pointing to an Element Web deployment. For example, https://app.element.io. This will change all permalinks (via the "Share" menus) to point at the Element Web deployment rather than matrix.to.

When using the share button, permalink_prefix should be used to generate links, but not when pinging people, since these aren't permalinks and are in theory just fallback links for clients which don't know how to render mentions.

Other than spec compliance, this breaks bridges, since bridges only deal with inline mentions as stated in the spec. Trying to ping a bridged user would send a link to the Element web instance instead, so it would be unsuccessful at getting their attention and make it unnecessarily obvious that the person on the other side is using a Matrix bridge.

Operating system

No response

Browser information

No response

URL for webapp

No response

Application version

Element version: 1.11.45

Homeserver

No response

Will you send logs?

No

[gabrc52]

Trying to give it a shot at fixing.

First attempt, no effect:

diff --git a/src/autocomplete/UserProvider.tsx b/src/autocomplete/UserProvider.tsx
index a934e9309a..a41b6ccbae 100644
--- a/src/autocomplete/UserProvider.tsx
+++ b/src/autocomplete/UserProvider.tsx
@@ -132,7 +132,7 @@ export default class UserProvider extends AutocompleteProvider {
                     completionId: user.userId,
                     type: "user",
                     suffix: selection.beginning && range!.start === 0 ? ": " : " ",
-                    href: makeUserPermalink(user.userId),
+                    href: makeUserPermalink(user.userId, true),
                     component: (
                         <PillCompletion title={displayName} description={description}>
                             <MemberAvatar member={user} width={24} height={24} />
diff --git a/src/utils/permalinks/Permalinks.ts b/src/utils/permalinks/Permalinks.ts
index 1a55b8408e..2629996d0c 100644
--- a/src/utils/permalinks/Permalinks.ts
+++ b/src/utils/permalinks/Permalinks.ts
@@ -273,8 +273,8 @@ export function makeGenericPermalink(entityId: string): string {
     return getPermalinkConstructor().forEntity(entityId);
 }
 
-export function makeUserPermalink(userId: string): string {
-    return getPermalinkConstructor().forUser(userId);
+export function makeUserPermalink(userId: string, isMention: boolean = false): string {
+    return getPermalinkConstructor(isMention).forUser(userId);
 }
 
 export function makeRoomPermalink(matrixClient: MatrixClient, roomId: string): string {
@@ -409,9 +409,9 @@ export function getPrimaryPermalinkEntity(permalink: string): string | null {
     return null;
 }
 
-function getPermalinkConstructor(): PermalinkConstructor {
+function getPermalinkConstructor(forceMatrixTo: boolean = false): PermalinkConstructor {
     const elementPrefix = SdkConfig.get("permalink_prefix");
-    if (elementPrefix && elementPrefix !== matrixtoBaseUrl) {
+    if (!forceMatrixTo && elementPrefix && elementPrefix !== matrixtoBaseUrl) {
         return new ElementPermalinkConstructor(elementPrefix);
     }