fix: prefer expected join link for pubkey

php/servers/servers-rooms.php

@@ -353,13 +353,22 @@
 			return "$base_url/r/$token/invite.png";
 		}
 
+		/**
+		 * Return a string used to match the in-app join URL for this room.
+		 */
+		function _get_join_url_match(): string {
+			$hostname = $this->server->get_hostname(include_port: true);
+			$token = $this->token;
+			return "$hostname/$token?public_key=";
+		}
+
 		/**
 		 * Return the in-app join URL for this room.
 		 */
 		function get_join_url(): string {
 			$base_url = $this->server->base_url;
-			$pubkey = $this->server->get_pubkey();
 			$token = $this->token;
+			$pubkey = $this->server->get_pubkey();
 			return "$base_url/$token?public_key=$pubkey";
 		}
 
@@ -1351,10 +1360,12 @@
 			}
 
 			// This is ugly. 'RoomBuilder' would be better.
-			$preview_url = CommunityRoom::_from_intermediate_data(
+			$room_intermediate = CommunityRoom::_from_intermediate_data(
 				$this,
 				$this->_intermediate_room_data[0]
-			)->get_preview_url();
+			);
+
+			$preview_url = $room_intermediate->get_preview_url();
 
 			log_info("Fetching pubkey from $preview_url");
 			$room_view_response = yield from FetchingCoroutine
@@ -1372,7 +1383,11 @@
 			}
 
 			$links = parse_join_links($room_view);
-			$link = $links[0];
+
+			$join_link_part = $room_intermediate->_get_join_url_match();
+			$link = array_values(array_filter($links, function (string $link) use ($join_link_part) {
+				return str_contains($link, $join_link_part);
+			}))[0] ?? $links[0];
 
 			if (!isset($link)) {
 				log_debug("Could not locate join link in preview at $preview_url.");