enum variants

_database/sql/migrations_squashed/AGENTS.md

@@ -13,6 +13,9 @@ Update the corresponding squashed file whenever a migration changes a table's sc
 
 - Primary key `id` columns must be `BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT`. Do not use signed IDs.
 - Always create tables with `ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin`.
+- Application-owned state/status/type columns must not have schema defaults. Required
+  values stay `NOT NULL` and are supplied explicitly by application code using the
+  corresponding Rust enum. Keep these definitions consistent with the applied migrations.
 - All SQL files should start with the standard IntelliJ noinspection comments:
   ```sql
   -- noinspection SqlDialectInspectionForFile

_database/sql/migrations_squashed/user_tables/user_login_challenges.sql

@@ -28,7 +28,8 @@ CREATE TABLE user_login_challenges (
   -- UserLoginChallengeStatus: pending, approved, redeemed, failed.
   -- Only pending may be approved/declined. Only approved may mint a session.
   -- Expiry is checked independently of status on EVERY approval/redemption request.
-  status VARCHAR(16) NOT NULL DEFAULT 'pending',
+  -- Application inserts explicitly bind UserLoginChallengeStatus::Pending.
+  status VARCHAR(16) NOT NULL,
 
   -- The authenticated web user who approved OR declined. NULL until a decision.
   -- On approval this becomes the immutable owner of the session to be minted.