diff --git a/src/engine/register.rs b/src/engine/register.rs
index 6659f7f..1ab918f 100644
--- a/src/engine/register.rs
+++ b/src/engine/register.rs
@@ -58,6 +58,11 @@ impl Engine {
 
     pub fn authority_register(&mut self, name: &str, creds: Option<db::Credentials>, email: Option<String>) -> AuthorityStatus {
         let Some(creds) = creds else { return AuthorityStatus::Internal };
+        // Re-check the freeze pre_check saw: defcon may have frozen registrations
+        // during the ~1s off-lock derivation between the two calls.
+        if self.db.registrations_frozen() || self.db.readonly() {
+            return AuthorityStatus::Invalid;
+        }
         // The IRC REGISTER rejects a FORBIDden email; a website write must too.
         if let Some(addr) = &email {
             if self.db.is_forbidden(echo_api::ForbidKind::Email, addr).is_some() {
@@ -89,6 +94,28 @@ impl Engine {
         self.db.scram_lookup(name, "SCRAM-SHA-256").map(|(a, v)| (a.to_string(), v.to_string()))
     }
 
+    /// gRPC login pre-check: apply the same guards the IRC IDENTIFY/SASL paths do
+    /// before the ~1s verify. Refuses a suspended or throttled account — the
+    /// website only sees a plain failure, so it can't tell these from a bad
+    /// password — and otherwise returns the canonical name + verifier to check
+    /// off the engine lock. Feed the result back through [`Self::authority_note_auth`].
+    pub fn authority_auth_begin(&self, name: &str) -> Option<(String, String)> {
+        if let Some(acc) = self.db.resolve_account(name) {
+            if self.db.is_suspended(acc) {
+                return None;
+            }
+        }
+        if self.db.auth_lockout(name).is_some() {
+            return None;
+        }
+        self.scram_verifier(name)
+    }
+
+    /// Record a gRPC login attempt in the brute-force backoff, exactly like IDENTIFY.
+    pub fn authority_note_auth(&mut self, name: &str, ok: bool) {
+        self.db.note_auth(name, ok);
+    }
+
     pub fn authority_set_password(&mut self, account: &str, creds: Option<db::Credentials>) -> AuthorityStatus {
         let Some(creds) = creds else { return AuthorityStatus::Internal };
         // set_credentials's only Err is Internal, which here always means "no such account".
diff --git a/src/grpc.rs b/src/grpc.rs
index f97812a..b12f09a 100644
--- a/src/grpc.rs
+++ b/src/grpc.rs
@@ -302,7 +302,7 @@ impl Accounts for AccountsService {
         // Fetch the verifier under the lock (cheap), then run the ~1s PBKDF2 on a
         // blocking thread — never hold the engine lock across it, or every login
         // freezes the whole daemon (IRC link, gossip, all RPCs).
-        let Some((account, verifier)) = self.engine.lock().await.scram_verifier(&msg.name) else {
+        let Some((account, verifier)) = self.engine.lock().await.authority_auth_begin(&msg.name) else {
             return Ok(Response::new(AuthenticateReply { status: PbStatus::Invalid as i32, account: String::new() }));
         };
         let password = msg.password;
@@ -311,6 +311,9 @@ impl Accounts for AccountsService {
         })
         .await
         .unwrap_or(false);
+        // Feed the brute-force backoff just like IDENTIFY, so the website login
+        // can't be used as an unthrottled password oracle against echo.
+        self.engine.lock().await.authority_note_auth(&msg.name, ok);
         if ok {
             Ok(Response::new(AuthenticateReply { status: PbStatus::Ok as i32, account }))
         } else {
@@ -621,6 +624,24 @@ mod tests {
         assert_eq!(bad.status, PbStatus::Invalid as i32);
     }
 
+    // The website login feeds the same brute-force backoff as IRC IDENTIFY, so it
+    // can't be used as an unthrottled password oracle: after enough wrong guesses
+    // even the correct password is refused while the lockout holds.
+    #[tokio::test]
+    async fn authenticate_throttles_repeated_failures() {
+        let (engine, _tx) = engine_with("acct-throttle");
+        let svc = accounts_svc(engine);
+        svc.register(authed(RegisterRequest { name: "carol".into(), password: "hunter2".into(), email: String::new() }, "t")).await.unwrap();
+
+        for _ in 0..10 {
+            let out = svc.authenticate(authed(AuthenticateRequest { name: "carol".into(), password: "nope".into() }, "t")).await.unwrap().into_inner();
+            assert_eq!(out.status, PbStatus::Invalid as i32);
+        }
+        // Correct password, but the account is now locked out.
+        let locked = svc.authenticate(authed(AuthenticateRequest { name: "carol".into(), password: "hunter2".into() }, "t")).await.unwrap().into_inner();
+        assert_eq!(locked.status, PbStatus::Invalid as i32, "throttled even with the right password");
+    }
+
     #[tokio::test]
     async fn provision_creates_account_from_verifiers() {
         let (engine, _tx) = engine_with("acct-provision");