From 203d55d2f72f5ff9df6be9870effdd80d008c6df Mon Sep 17 00:00:00 2001
From: Ginger <ginger@gingershaped.computer>
Date: Thu, 26 Mar 2026 10:48:35 -0400
Subject: [PATCH] refactor: Remove workarounds for matrix-appservice-irc

---
 src/api/client/account/mod.rs      | 40 ++++++------------------------
 src/api/client/account/register.rs | 23 +++--------------
 2 files changed, 11 insertions(+), 52 deletions(-)

diff --git a/src/api/client/account/mod.rs b/src/api/client/account/mod.rs
index dad027c5b..88181fac5 100644
--- a/src/api/client/account/mod.rs
+++ b/src/api/client/account/mod.rs
@@ -51,49 +51,23 @@ pub(crate) async fn get_register_available_route(
 	InsecureClientIp(client): InsecureClientIp,
 	body: Ruma<get_username_availability::v3::Request>,
 ) -> Result<get_username_availability::v3::Response> {
-	// workaround for https://github.com/matrix-org/matrix-appservice-irc/issues/1780 due to inactivity of fixing the issue
-	let is_matrix_appservice_irc = body.appservice_info.as_ref().is_some_and(|appservice| {
-		appservice.registration.id == "irc"
-			|| appservice.registration.id.contains("matrix-appservice-irc")
-			|| appservice.registration.id.contains("matrix_appservice_irc")
-	});
-
-	if services
-		.globals
-		.forbidden_usernames()
-		.is_match(&body.username)
-	{
-		return Err!(Request(Forbidden("Username is forbidden")));
-	}
-
-	// don't force the username lowercase if it's from matrix-appservice-irc
-	let body_username = if is_matrix_appservice_irc {
-		body.username.clone()
-	} else {
-		body.username.to_lowercase()
-	};
-
 	// Validate user id
 	let user_id =
-		match UserId::parse_with_server_name(&body_username, services.globals.server_name()) {
+		match UserId::parse_with_server_name(&body.username, services.globals.server_name()) {
 			| Ok(user_id) => {
 				if let Err(e) = user_id.validate_strict() {
-					// unless the username is from the broken matrix appservice IRC bridge, we
-					// should follow synapse's behaviour on not allowing things like spaces
-					// and UTF-8 characters in usernames
-					if !is_matrix_appservice_irc {
-						return Err!(Request(InvalidUsername(debug_warn!(
-							"Username {body_username} contains disallowed characters or spaces: \
-							 {e}"
-						))));
-					}
+					return Err!(Request(InvalidUsername(debug_warn!(
+						"Username {} contains disallowed characters or spaces: {e}",
+						body.username
+					))));
 				}
 
 				user_id
 			},
 			| Err(e) => {
 				return Err!(Request(InvalidUsername(debug_warn!(
-					"Username {body_username} is not valid: {e}"
+					"Username {} is not valid: {e}",
+					body.username
 				))));
 			},
 		};
diff --git a/src/api/client/account/register.rs b/src/api/client/account/register.rs
index 6aa034018..4d445f036 100644
--- a/src/api/client/account/register.rs
+++ b/src/api/client/account/register.rs
@@ -125,7 +125,6 @@ pub(crate) async fn register_route(
 	let user_id = determine_registration_user_id(
 		&services,
 		body.username.clone(),
-		body.appservice_info.as_ref(),
 		is_guest,
 		emergency_mode_enabled,
 	)
@@ -478,11 +477,10 @@ async fn create_registration_uiaa_session(
 async fn determine_registration_user_id(
 	services: &Services,
 	supplied_username: Option<String>,
-	appservice_info: Option<&service::appservice::RegistrationInfo>,
 	is_guest: bool,
 	emergency_mode_enabled: bool,
 ) -> Result<OwnedUserId> {
-	if let Some(mut supplied_username) = supplied_username
+	if let Some(supplied_username) = supplied_username
 		&& !is_guest
 	{
 		// The user gets to pick their username. Do some validation to make sure it's
@@ -498,18 +496,6 @@ async fn determine_registration_user_id(
 			return Err!(Request(Forbidden("Username is forbidden")));
 		}
 
-		// Workaround for https://github.com/matrix-org/matrix-appservice-irc/issues/1780 due to inactivity of fixing the issue
-		let is_matrix_appservice_irc = appservice_info.is_some_and(|appservice| {
-			appservice.registration.id == "irc"
-				|| appservice.registration.id.contains("matrix-appservice-irc")
-				|| appservice.registration.id.contains("matrix_appservice_irc")
-		});
-
-		// Don't force the username lowercase if it's from matrix-appservice-irc.
-		if !is_matrix_appservice_irc {
-			supplied_username = supplied_username.to_lowercase();
-		}
-
 		// Create and validate the user ID
 		let user_id = match UserId::parse_with_server_name(
 			&supplied_username,
@@ -517,10 +503,9 @@ async fn determine_registration_user_id(
 		) {
 			| Ok(user_id) => {
 				if let Err(e) = user_id.validate_strict() {
-					// unless the username is from the broken matrix appservice IRC bridge, or
-					// we are in emergency mode, we should follow synapse's behaviour on
+					// Unless we are in emergency mode, we should follow synapse's behaviour on
 					// not allowing things like spaces and UTF-8 characters in usernames
-					if !is_matrix_appservice_irc && !emergency_mode_enabled {
+					if !emergency_mode_enabled {
 						return Err!(Request(InvalidUsername(debug_warn!(
 							"Username {supplied_username} contains disallowed characters or \
 							 spaces: {e}"
@@ -550,7 +535,7 @@ async fn determine_registration_user_id(
 
 		Ok(user_id)
 	} else {
-		// The user is a guest or is lacking in creativity. Generate a username for
+		// The user is a guest or didn't specify a username. Generate a username for
 		// them.
 
 		loop {