diff --git a/backend/crates/gateway-store/tests/postgres/proxies.rs b/backend/crates/gateway-store/tests/postgres/proxies.rs
index 852c212aa..c81b87d64 100644
--- a/backend/crates/gateway-store/tests/postgres/proxies.rs
+++ b/backend/crates/gateway-store/tests/postgres/proxies.rs
@@ -834,7 +834,7 @@ async fn migration_backfills_shared_proxies_without_changing_credentials() {
     .await
     .unwrap();
     sqlx::raw_sql(include_str!(
-        "../../../../migrations/0012_proxy_request_location.sql"
+        "../../../../migrations/0011_proxy_request_location.sql"
     ))
     .execute(&database.pool)
     .await
diff --git a/backend/crates/gateway-store/tests/postgres/runtime_settings.rs b/backend/crates/gateway-store/tests/postgres/runtime_settings.rs
index 0daeb0e78..47518906f 100644
--- a/backend/crates/gateway-store/tests/postgres/runtime_settings.rs
+++ b/backend/crates/gateway-store/tests/postgres/runtime_settings.rs
@@ -355,7 +355,7 @@ async fn request_location_defaults_and_updates_reach_the_runtime_snapshot() {
 }
 
 #[tokio::test]
-async fn auto_freeze_defaults_off_and_migration_preserves_explicit_opt_in() {
+async fn auto_freeze_defaults_off_and_explicit_opt_in_round_trips() {
     let Some(database) = TestDatabase::create("freeze_opt_in").await else {
         return;
     };
@@ -367,32 +367,10 @@ async fn auto_freeze_defaults_off_and_migration_preserves_explicit_opt_in() {
             .expect("default settings")
             .account_auto_freeze_enabled
     );
-    sqlx::query("update runtime_settings set account_auto_freeze_enabled = true where id = 1")
-        .execute(&database.pool)
-        .await
-        .expect("old default");
-    let migration = include_str!("../../../../migrations/0011_account_auto_freeze_opt_in.sql");
-    sqlx::raw_sql(migration)
-        .execute(&database.pool)
-        .await
-        .expect("migrate untouched default");
-    assert!(
-        !repository
-            .load_runtime_settings()
-            .await
-            .expect("settings")
-            .account_auto_freeze_enabled
-    );
-    sqlx::query("update runtime_settings set account_auto_freeze_enabled = true where id = 1")
-        .execute(&database.pool)
+    repository
+        .update_runtime_settings(settings_with_margin(3_600))
         .await
         .expect("explicit opt-in");
-    sqlx::query("insert into admin_audit_events (id, actor_kind, actor_ref, action, entity_kind, entity_ref, changed_fields, created_at) values ('freeze-opt-in', 'system', 'test', 'settings.replace', 'runtime_settings', '1', array['account_auto_freeze'], now())")
-        .execute(&database.pool).await.expect("saved settings audit");
-    sqlx::raw_sql(migration)
-        .execute(&database.pool)
-        .await
-        .expect("preserve opt-in");
     assert!(
         repository
             .load_runtime_settings()
diff --git a/backend/migrations/.frozen-sha256 b/backend/migrations/.frozen-sha256
index e9b314ae7..5cc72da1a 100644
--- a/backend/migrations/.frozen-sha256
+++ b/backend/migrations/.frozen-sha256
@@ -7,6 +7,5 @@ b7d3df7b48d835a00a3b74cbefc958a039d38fea5529cdad04bfbc703dca72aa  0001_initial.s
 18e8c1b71c896a9d576d9e4ef9701506f654f55383af908898195b9eb2980fde  0007_account_notes.sql
 36b720c9d3e6bf0bdb799b9b6a89b81638c642ac866992a880bd82357012a208  0008_concurrency_queues.sql
 161df9ae43da34d51b340bbf95d71c61a8c1a2aa142382f693a9d127c834630d  0009_account_model_access.sql
-dd4aa34e9bcf1698bb9688421964bbf410314d8e905448b8229460b972cff2f6  0010_account_auto_freeze.sql
-9bd261b7e94872126754eb7f749c56187264a47c567b0bef5c394d6776b4f463  0011_account_auto_freeze_opt_in.sql
-ae7f7acb3014f0a60d979dd9c04b3065322b206e42eb6256505baf78caf9dd22  0012_proxy_request_location.sql
+3751a802e80b5d538abc5619a2397aa4bf13f52076068a489892f664907adf49  0010_account_auto_freeze.sql
+ae7f7acb3014f0a60d979dd9c04b3065322b206e42eb6256505baf78caf9dd22  0011_proxy_request_location.sql
diff --git a/backend/migrations/0010_account_auto_freeze.sql b/backend/migrations/0010_account_auto_freeze.sql
index 9abaa3c9d..534afee72 100644
--- a/backend/migrations/0010_account_auto_freeze.sql
+++ b/backend/migrations/0010_account_auto_freeze.sql
@@ -1,8 +1,8 @@
 -- 账号容量熔断：统计窗口内高频出现容量类上游错误时自动冻结账号一段时间；
 -- 恢复前可选执行一次探测调用验证上游已恢复；冻结期间按观测到的在途并发峰值
--- 下调账号并发上限，让账号带着更安全的并发配置自愈。默认启用，已有实例可关闭。
+-- 下调账号并发上限，让账号带着更安全的并发配置自愈。默认关闭，需在设置页显式启用。
 alter table runtime_settings
-    add column account_auto_freeze_enabled boolean not null default true,
+    add column account_auto_freeze_enabled boolean not null default false,
     add column account_auto_freeze_threshold bigint not null default 12
         check (account_auto_freeze_threshold between 2 and 1000),
     add column account_auto_freeze_window_seconds bigint not null default 600
diff --git a/backend/migrations/0011_account_auto_freeze_opt_in.sql b/backend/migrations/0011_account_auto_freeze_opt_in.sql
deleted file mode 100644
index 70f0dcb1b..000000000
--- a/backend/migrations/0011_account_auto_freeze_opt_in.sql
+++ /dev/null
@@ -1,12 +0,0 @@
--- 自动冻结默认关闭；保留已经通过设置页显式保存的冻结配置。
-alter table runtime_settings
-    alter column account_auto_freeze_enabled set default false;
-
-update runtime_settings
-set account_auto_freeze_enabled = false
-where account_auto_freeze_enabled = true
-  and not exists (
-    select 1 from admin_audit_events
-    where action = 'settings.replace'
-      and changed_fields @> array['account_auto_freeze']::text[]
-  );
diff --git a/backend/migrations/0012_proxy_request_location.sql b/backend/migrations/0011_proxy_request_location.sql
similarity index 100%
rename from backend/migrations/0012_proxy_request_location.sql
rename to backend/migrations/0011_proxy_request_location.sql