improve form pre-completion

controllers/main.py

 from odoo import http, tools, _
+from odoo.addons.web.controllers.home import SIGN_UP_REQUEST_PARAMS
+
 from odoo.addons.auth_signup.controllers.main import AuthSignupHome
 
+# add firstname and lastname to qcontext whitelist
+SIGN_UP_REQUEST_PARAMS.update({"firstname", "lastname"})
+
 class SolagroAuthSignupHome(AuthSignupHome):
     @http.route('/web/signup', type='http', auth='public', website=True, sitemap=False)
     def web_auth_signup(self, **post):

views/auth_signup_login_templates.xml

@@ -15,6 +15,7 @@
         <xpath expr="//input[@id='login']" position="attributes">
             <attribute name="type">email</attribute>
             <attribute name="name">email</attribute>
+            <attribute name="t-att-value">email</attribute>
             <attribute name="t-attf-class">form-control {{'is-invalid' if error_email else ''}}</attribute>
         </xpath>