relax totp time

lib/towerops/accounts.ex

@@ -196,10 +196,11 @@ defmodule Towerops.Accounts do
   Verifies a TOTP code against a secret.
 
   Returns true if the code is valid within the time window, false otherwise.
+  Allows for +/- 1 time step (30 seconds) to handle clock drift.
   """
   def verify_totp(secret, code) when is_binary(secret) and is_binary(code) do
-    # Allow 30 second window for time drift
-    NimbleTOTP.valid?(secret, code, since: System.system_time(:second) - 30)
+    # NimbleTOTP.valid? by default checks current time +/- 1 time step (30s)
+    NimbleTOTP.valid?(secret, code)
   end
 
   @doc """

test/towerops/accounts_test.exs

@@ -441,7 +441,7 @@ defmodule Towerops.AccountsTest do
       # Generate code for current time (should always be valid)
       code = NimbleTOTP.verification_code(secret)
 
-      # Verify it works with the time window check (since: -30)
+      # Verify it works (checks current time +/- 1 step)
       assert Accounts.verify_totp(secret, code)
     end