diff --git a/packages/overlays/matrix-synapse/patches/0008-Add-option-to-allow-registrations-that-begin-with-_-.patch b/packages/overlays/matrix-synapse/patches/0008-Add-option-to-allow-registrations-that-begin-with-_-.patch
deleted file mode 100644
index fa37022..0000000
--- a/packages/overlays/matrix-synapse/patches/0008-Add-option-to-allow-registrations-that-begin-with-_-.patch
+++ /dev/null
@@ -1,116 +0,0 @@
-From 44ae5362fd952dbb209f4b52ee9c96641163f032 Mon Sep 17 00:00:00 2001
-From: _ <x5f@fastmail.com>
-Date: Thu, 15 May 2025 04:31:52 -0700
-Subject: [PATCH 08/34] Add option to allow registrations that begin with '_'
- (#18262)
-
-Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>
----
- changelog.d/18262.feature | 1 +
- .../configuration/config_documentation.md | 14 +++++++++++
- synapse/config/registration.py | 4 ++++
- synapse/handlers/register.py | 5 +++-
- tests/handlers/test_register.py | 23 +++++++++++++++++++
- 5 files changed, 46 insertions(+), 1 deletion(-)
- create mode 100644 changelog.d/18262.feature
-
-diff --git a/changelog.d/18262.feature b/changelog.d/18262.feature
-new file mode 100644
-index 0000000000..c8249faa76
---- /dev/null
-+++ b/changelog.d/18262.feature
-@@ -0,0 +1 @@
-+Add option to allow registrations that begin with `_`. Contributed by `_` (@hex5f).
-diff --git a/docs/usage/configuration/config_documentation.md b/docs/usage/configuration/config_documentation.md
-index 2228c18a6c..e688bc5cd8 100644
---- a/docs/usage/configuration/config_documentation.md
-+++ b/docs/usage/configuration/config_documentation.md
-@@ -2887,6 +2887,20 @@ Example configuration:
- inhibit_user_in_use_error: true
- ```
- ---
-+### `allow_underscore_prefixed_registration`
-+
-+Whether users are allowed to register with a underscore-prefixed localpart.
-+By default, AppServices use prefixes like `_example` to namespace their
-+associated ghost users. If turned on, this may result in clashes or confusion.
-+Useful when provisioning users from an external identity provider.
-+
-+Defaults to false.
-+
-+Example configuration:
-+```yaml
-+allow_underscore_prefixed_registration: false
-+```
-+---
- ## User session management
- ---
- ### `session_lifetime`
-diff --git a/synapse/config/registration.py b/synapse/config/registration.py
-index 3cf7031656..8adf21079e 100644
---- a/synapse/config/registration.py
-+++ b/synapse/config/registration.py
-@@ -162,6 +162,10 @@ class RegistrationConfig(Config):
- "disable_msisdn_registration", False
- )
-
-+ self.allow_underscore_prefixed_localpart = config.get(
-+ "allow_underscore_prefixed_localpart", False
-+ )
-+
- session_lifetime = config.get("session_lifetime")
- if session_lifetime is not None:
- session_lifetime = self.parse_duration(session_lifetime)
-diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
-index ecfea175c7..3e86349981 100644
---- a/synapse/handlers/register.py
-+++ b/synapse/handlers/register.py
-@@ -159,7 +159,10 @@ class RegistrationHandler:
- if not localpart:
- raise SynapseError(400, "User ID cannot be empty", Codes.INVALID_USERNAME)
-
-- if localpart[0] == "_":
-+ if (
-+ localpart[0] == "_"
-+ and not self.hs.config.registration.allow_underscore_prefixed_localpart
-+ ):
- raise SynapseError(
- 400, "User ID may not begin with _", Codes.INVALID_USERNAME
- )
-diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
-index 92487692db..dda389c08b 100644
---- a/tests/handlers/test_register.py
-+++ b/tests/handlers/test_register.py
-@@ -588,6 +588,29 @@ class RegistrationTestCase(unittest.HomeserverTestCase):
- d = self.store.is_support_user(user_id)
- self.assertFalse(self.get_success(d))
-
-+ def test_underscore_localpart_rejected_by_default(self) -> None:
-+ for invalid_user_id in ("_", "_prefixed"):
-+ with self.subTest(invalid_user_id=invalid_user_id):
-+ self.get_failure(
-+ self.handler.register_user(localpart=invalid_user_id),
-+ SynapseError,
-+ )
-+
-+ @override_config(
-+ {
-+ "allow_underscore_prefixed_localpart": True,
-+ }
-+ )
-+ def test_underscore_localpart_allowed_if_configured(self) -> None:
-+ for valid_user_id in ("_", "_prefixed"):
-+ with self.subTest(valid_user_id=valid_user_id):
-+ user_id = self.get_success(
-+ self.handler.register_user(
-+ localpart=valid_user_id,
-+ ),
-+ )
-+ self.assertEqual(user_id, f"@{valid_user_id}:test")
-+
- def test_invalid_user_id(self) -> None:
- invalid_user_id = "^abcd"
- self.get_failure(
---
-2.49.0
-
|
