diff --git a/website_membership_signup_required/models/__init__.py b/website_membership_signup_required/models/__init__.py
index 8606c32..c77ee6b 100644
--- a/website_membership_signup_required/models/__init__.py
+++ b/website_membership_signup_required/models/__init__.py
@@ -2,4 +2,5 @@
 
 from . import website
 from . import res_config_settings
+from . import res_partner
 from . import res_users
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diff --git a/website_membership_signup_required/models/res_partner.py b/website_membership_signup_required/models/res_partner.py
new file mode 100644
index 0000000..84e1c2d
--- /dev/null
+++ b/website_membership_signup_required/models/res_partner.py
@@ -0,0 +1,32 @@
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import api, models
+
+
+class ResPartner(models.Model):
+    _inherit = "res.partner"
+
+    @api.model
+    def _signup_retrieve_info(self, token):
+        """Extend the core's token-based signup info with `firstname` and
+        `lastname` so the signup form (extended by this module to collect
+        them separately via `partner_firstname`) can be pre-filled and
+        shown readonly when the visitor follows an invitation link.
+
+        The core (`auth_signup/models/res_partner.py:_signup_retrieve_info`)
+        only returns `name`, `login` and `email`. Our signup template
+        replaced the single `name` input with `firstname` / `lastname`
+        inputs, so without this override those inputs would be empty (and
+        readonly, because `only_passwords` is True for token flows) when
+        an invited partner already has the split fields populated.
+
+        We keep `name` in the returned dict (the core's contract) and add
+        the two split fields so the controller's `setdefault` populates
+        the qcontext transparently.
+        """
+        res = super()._signup_retrieve_info(token)
+        partner = self._get_partner_from_token(token)
+        if partner:
+            res["firstname"] = partner.firstname or ""
+            res["lastname"] = partner.lastname or ""
+        return res
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diff --git a/website_membership_signup_required/tests/test_membership_signup.py b/website_membership_signup_required/tests/test_membership_signup.py
index 6caa1ef..0216cb5 100644
--- a/website_membership_signup_required/tests/test_membership_signup.py
+++ b/website_membership_signup_required/tests/test_membership_signup.py
@@ -227,4 +227,52 @@ class TestMembershipSignup(TransactionCase):
         ctrl = WebsiteSaleMembershipSignup()
         billing_fields = ctrl._get_mandatory_billing_address_fields(country)
         self.assertNotIn("phone", billing_fields)
-        self.assertIn("email", billing_fields)
\ No newline at end of file
+        self.assertIn("email", billing_fields)
+
+    # -- Token-based signup: pre-fill firstname / lastname -----------------
+
+    def test_12_signup_retrieve_info_returns_firstname_lastname(self):
+        """When a partner is invited via token (the email-invitation flow),
+        the core's `_signup_retrieve_info` only returns `name`. Our
+        `res.partner` override adds `firstname` / `lastname` so the signup
+        form (extended by this module to collect them separately) is
+        pre-filled when the invited partner already has the split fields
+        (which is the case with `partner_firstname` installed).
+
+        The invited partner must NOT have a user yet, otherwise the token
+        payload check (`user_ids`) won't match.
+        """
+        partner = self.env["res.partner"].create({
+            "firstname": "Invited",
+            "lastname": "Researcher",
+            "email": "invited.researcher@example.com",
+            "signup_type": "signup",
+        })
+        self.assertFalse(partner.user_ids, "test precondition: no user yet")
+        token = partner._generate_signup_token()
+        info = self.env["res.partner"]._signup_retrieve_info(token)
+        self.assertEqual(info.get("firstname"), "Invited")
+        self.assertEqual(info.get("lastname"), "Researcher")
+        self.assertEqual(info.get("name"), partner.name)
+        self.assertEqual(info.get("email"), "invited.researcher@example.com")
+
+    def test_13_signup_retrieve_info_legacy_partner_without_split(self):
+        """A partner created without `firstname`/`lastname` (legacy, only
+        `name`) should not crash the override. `firstname`/`lastname` come
+        back as '' (falsy), `name` as the legacy value, and the token flow
+        still works — the form will show empty readonly inputs for the split
+        fields, which is the best we can do without re-splitting.
+        """
+        partner = self.env["res.partner"].create({
+            "name": "Legacy Researcher",
+            "email": "legacy@example.com",
+            "signup_type": "signup",
+        })
+        # partner_firstname's post_create hook may or may not have split
+        # `name` automatically; we just check the override does not crash
+        # and returns the contract keys.
+        token = partner._generate_signup_token()
+        info = self.env["res.partner"]._signup_retrieve_info(token)
+        self.assertIn("firstname", info)
+        self.assertIn("lastname", info)
+        self.assertEqual(info.get("name"), partner.name)
\ No newline at end of file