diff --git a/backend/internal/repository/account_repo.go b/backend/internal/repository/account_repo.go
index fb59de6717..93ea6451f6 100644
--- a/backend/internal/repository/account_repo.go
+++ b/backend/internal/repository/account_repo.go
@@ -653,6 +653,10 @@ func (r *accountRepository) ListOAuthRefreshCandidates(ctx context.Context) ([]s
 	if r.sql == nil {
 		return nil, errors.New("account repository SQL executor not configured")
 	}
+	// (cond) IS NOT TRUE 把 NULL 和 FALSE 都视为"可被刷新"。直接写
+	// NOT (a AND b) 在 PG 三值逻辑下会把 a 或 b 为 NULL 的行（即绝大多数
+	// 健康账号：temp_unschedulable_until=NULL）也排除，导致后台 token
+	// 刷新工作器漏掉所有正常账号 → access_token 到期后请求开始 401。
 	rows, err := r.sql.QueryContext(ctx, `
 		SELECT id
 		FROM accounts
@@ -662,10 +666,10 @@ func (r *accountRepository) ListOAuthRefreshCandidates(ctx context.Context) ([]s
 			AND platform IN ('anthropic', 'openai', 'gemini', 'antigravity')
 			AND credentials ? 'refresh_token'
 			AND btrim(credentials->>'refresh_token') <> ''
-			AND NOT (
+			AND (
 				temp_unschedulable_until > NOW()
 				AND temp_unschedulable_reason LIKE 'token refresh retry exhausted:%'
-			)
+			) IS NOT TRUE
 		ORDER BY priority ASC, id ASC
 	`)
 	if err != nil {
diff --git a/backend/internal/repository/account_repo_temp_unsched_test.go b/backend/internal/repository/account_repo_temp_unsched_test.go
index e802e3b0cb..eb123ee6a3 100644
--- a/backend/internal/repository/account_repo_temp_unsched_test.go
+++ b/backend/internal/repository/account_repo_temp_unsched_test.go
@@ -49,6 +49,10 @@ func TestAccountRepository_ListOAuthRefreshCandidates_SQLFilter(t *testing.T) {
 	require.Contains(t, normalized, "btrim(credentials->>'refresh_token') <> ''")
 	require.Contains(t, normalized, "temp_unschedulable_until > NOW()")
 	require.Contains(t, normalized, "temp_unschedulable_reason LIKE 'token refresh retry exhausted:%'")
+	require.Contains(t, normalized, "IS NOT TRUE",
+		"must use IS NOT TRUE so accounts with NULL temp_unschedulable_until are not silently excluded by PG 3-valued logic")
+	require.NotContains(t, normalized, "AND NOT (",
+		"plain NOT (...) excludes NULL temp_unschedulable_until rows (the common healthy case)")
 	require.Contains(t, normalized, "ORDER BY priority ASC, id ASC")
 	require.NotContains(t, normalized, "credentials->>'expires_at'")
 	require.NoError(t, mock.ExpectationsWereMet())
diff --git a/backend/internal/server/api_contract_test.go b/backend/internal/server/api_contract_test.go
index 8a103c509b..6ae4a9dff2 100644
--- a/backend/internal/server/api_contract_test.go
+++ b/backend/internal/server/api_contract_test.go
@@ -1681,6 +1681,10 @@ func (s *stubAccountRepo) ListActive(ctx context.Context) ([]service.Account, er
 	return nil, errors.New("not implemented")
 }
 
+func (s *stubAccountRepo) ListOAuthRefreshCandidates(ctx context.Context) ([]service.Account, error) {
+	return nil, errors.New("not implemented")
+}
+
 func (s *stubAccountRepo) ListByPlatform(ctx context.Context, platform string) ([]service.Account, error) {
 	return nil, errors.New("not implemented")
 }