diff --git a/auth/server/src/api/login/local.rs b/auth/server/src/api/login/local.rs
index 289a630..24cddf5 100644
--- a/auth/server/src/api/login/local.rs
+++ b/auth/server/src/api/login/local.rs
@@ -24,7 +24,7 @@ pub async fn sign_up_local_user<I: AuthImpl + ?Sized>(
 
   let no_users_exist = auth.no_users_exist().await?;
 
-  if auth.registration_disabled() && !no_users_exist {
+  if auth.local_registration_disabled() && !no_users_exist {
     return Err(
       anyhow!("User registration is disabled")
         .status_code(StatusCode::UNAUTHORIZED),
diff --git a/auth/server/src/api/login/mod.rs b/auth/server/src/api/login/mod.rs
index 31541cf..c069b23 100644
--- a/auth/server/src/api/login/mod.rs
+++ b/auth/server/src/api/login/mod.rs
@@ -115,7 +115,7 @@ pub fn get_login_options<I: AuthImpl + ?Sized>(
       .google_config()
       .map(|config| config.enabled())
       .unwrap_or_default(),
-    registration_disabled: auth.registration_disabled(),
+    registration_disabled: auth.local_registration_disabled(),
   }
 }
 
@@ -128,6 +128,170 @@ impl Resolve<LoginArgs> for GetLoginOptions {
   }
 }
 
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use crate::AuthImpl;
+  use mogh_auth_client::config::OidcConfig;
+
+  /// Minimal AuthImpl for testing
+  struct TestAuth {
+    local: bool,
+    oidc: Option<OidcConfig>,
+    registration_disabled: bool,
+    local_registration_disabled: Option<bool>,
+    oidc_registration_disabled: Option<bool>,
+  }
+
+  impl TestAuth {
+    fn default_test() -> Self {
+      Self {
+        local: true,
+        oidc: None,
+        registration_disabled: false,
+        local_registration_disabled: None,
+        oidc_registration_disabled: None,
+      }
+    }
+  }
+
+  impl AuthImpl for TestAuth {
+    fn new() -> Self {
+      Self::default_test()
+    }
+
+    fn local_auth_enabled(&self) -> bool {
+      self.local
+    }
+
+    fn oidc_config(&self) -> Option<&OidcConfig> {
+      self.oidc.as_ref()
+    }
+
+    fn registration_disabled(&self) -> bool {
+      self.registration_disabled
+    }
+
+    fn local_registration_disabled(&self) -> bool {
+      self
+        .local_registration_disabled
+        .unwrap_or_else(|| self.registration_disabled())
+    }
+
+    fn oidc_registration_disabled(&self) -> bool {
+      self
+        .oidc_registration_disabled
+        .unwrap_or_else(|| self.registration_disabled())
+    }
+
+    fn get_user(
+      &self,
+      _user_id: String,
+    ) -> crate::DynFuture<mogh_error::Result<crate::user::BoxAuthUser>>
+    {
+      Box::pin(async {
+        Err(anyhow::anyhow!("not implemented").into())
+      })
+    }
+
+    fn handle_request_authentication(
+      &self,
+      _auth: crate::RequestAuthentication,
+      _require_user_enabled: bool,
+      _req: axum::extract::Request,
+    ) -> crate::DynFuture<mogh_error::Result<axum::extract::Request>>
+    {
+      Box::pin(async {
+        Err(anyhow::anyhow!("not implemented").into())
+      })
+    }
+
+    fn jwt_provider(
+      &self,
+    ) -> &crate::provider::jwt::JwtProvider {
+      panic!("not needed for these tests")
+    }
+  }
+
+  #[test]
+  fn test_default_granular_methods_delegate_to_registration_disabled()
+  {
+    // When granular overrides are None, they should
+    // fall back to the global registration_disabled flag.
+    let auth = TestAuth {
+      registration_disabled: true,
+      ..TestAuth::default_test()
+    };
+    assert!(auth.local_registration_disabled());
+    assert!(auth.oidc_registration_disabled());
+    assert!(auth.github_registration_disabled());
+    assert!(auth.google_registration_disabled());
+  }
+
+  #[test]
+  fn test_global_disabled_local_override_enabled() {
+    // Global registration disabled, but local override allows it
+    let auth = TestAuth {
+      registration_disabled: true,
+      local_registration_disabled: Some(false),
+      ..TestAuth::default_test()
+    };
+    assert!(!auth.local_registration_disabled());
+    assert!(auth.oidc_registration_disabled());
+  }
+
+  #[test]
+  fn test_global_enabled_local_override_disabled() {
+    // Global registration enabled, but local override blocks it
+    let auth = TestAuth {
+      registration_disabled: false,
+      local_registration_disabled: Some(true),
+      ..TestAuth::default_test()
+    };
+    assert!(auth.local_registration_disabled());
+    assert!(!auth.oidc_registration_disabled());
+  }
+
+  #[test]
+  fn test_disable_local_allow_oidc() {
+    // The #1087 use case: disable local signup, allow OIDC
+    let auth = TestAuth {
+      registration_disabled: false,
+      local_registration_disabled: Some(true),
+      oidc_registration_disabled: Some(false),
+      ..TestAuth::default_test()
+    };
+    assert!(auth.local_registration_disabled());
+    assert!(!auth.oidc_registration_disabled());
+  }
+
+  #[test]
+  fn test_registration_disabled_reflects_local_in_login_options() {
+    // registration_disabled in the response controls the Sign Up button,
+    // which is local-only. It should reflect local_registration_disabled.
+    let auth = TestAuth {
+      registration_disabled: false,
+      local_registration_disabled: Some(true),
+      oidc_registration_disabled: Some(false),
+      ..TestAuth::default_test()
+    };
+    let opts = get_login_options(&auth);
+    assert!(opts.registration_disabled);
+  }
+
+  #[test]
+  fn test_registration_disabled_false_when_local_allowed() {
+    let auth = TestAuth {
+      registration_disabled: true,
+      local_registration_disabled: Some(false),
+      oidc_registration_disabled: Some(true),
+      ..TestAuth::default_test()
+    };
+    let opts = get_login_options(&auth);
+    assert!(!opts.registration_disabled);
+  }
+}
+
 impl Resolve<LoginArgs> for ExchangeForJwt {
   #[instrument("ExchangeForJwt", skip_all, fields(ip = ip.to_string()))]
   async fn resolve(
diff --git a/auth/server/src/api/named/github.rs b/auth/server/src/api/named/github.rs
index 6f0e4d9..42dcf3d 100644
--- a/auth/server/src/api/named/github.rs
+++ b/auth/server/src/api/named/github.rs
@@ -174,7 +174,7 @@ pub async fn github_callback<I: AuthImpl>(
       None => {
         let no_users_exist = auth.no_users_exist().await?;
 
-        if auth.registration_disabled() && !no_users_exist {
+        if auth.github_registration_disabled() && !no_users_exist {
           return Err(
             anyhow!("User registration is disabled")
               .status_code(StatusCode::UNAUTHORIZED),
diff --git a/auth/server/src/api/named/google.rs b/auth/server/src/api/named/google.rs
index d0e9157..f78bf63 100644
--- a/auth/server/src/api/named/google.rs
+++ b/auth/server/src/api/named/google.rs
@@ -172,7 +172,7 @@ pub async fn google_callback<I: AuthImpl>(
       None => {
         let no_users_exist = auth.no_users_exist().await?;
 
-        if auth.registration_disabled() && !no_users_exist {
+        if auth.google_registration_disabled() && !no_users_exist {
           return Err(
             anyhow!("User registration is disabled")
               .status_code(StatusCode::UNAUTHORIZED),
diff --git a/auth/server/src/api/oidc.rs b/auth/server/src/api/oidc.rs
index 74509c4..b5b2207 100644
--- a/auth/server/src/api/oidc.rs
+++ b/auth/server/src/api/oidc.rs
@@ -243,7 +243,7 @@ pub async fn oidc_callback<I: AuthImpl>(
       None => {
         let no_users_exist = auth.no_users_exist().await?;
 
-        if auth.registration_disabled() && !no_users_exist {
+        if auth.oidc_registration_disabled() && !no_users_exist {
           return Err(
             anyhow!("User registration is disabled")
               .status_code(StatusCode::UNAUTHORIZED),
diff --git a/auth/server/src/lib.rs b/auth/server/src/lib.rs
index 417c4ec..7f57729 100644
--- a/auth/server/src/lib.rs
+++ b/auth/server/src/lib.rs
@@ -79,11 +79,35 @@ pub trait AuthImpl: Send + Sync + 'static {
     "/auth"
   }
 
-  /// Disable new user registration.
+  /// Disable new user registration (all providers).
   fn registration_disabled(&self) -> bool {
     false
   }
 
+  /// Disable new user registration for local (username/password) signups only.
+  /// Defaults to [Self::registration_disabled].
+  fn local_registration_disabled(&self) -> bool {
+    self.registration_disabled()
+  }
+
+  /// Disable new user registration via OIDC only.
+  /// Defaults to [Self::registration_disabled].
+  fn oidc_registration_disabled(&self) -> bool {
+    self.registration_disabled()
+  }
+
+  /// Disable new user registration via GitHub only.
+  /// Defaults to [Self::registration_disabled].
+  fn github_registration_disabled(&self) -> bool {
+    self.registration_disabled()
+  }
+
+  /// Disable new user registration via Google only.
+  /// Defaults to [Self::registration_disabled].
+  fn google_registration_disabled(&self) -> bool {
+    self.registration_disabled()
+  }
+
   /// Provide usernames to lock credential updates for,
   /// such as demo users.
   fn locked_usernames(&self) -> &'static [String] {