diff --git a/fusion_plating/fusion_plating_shopfloor/models/res_users.py b/fusion_plating/fusion_plating_shopfloor/models/res_users.py
index 0e470982..9710afb3 100644
--- a/fusion_plating/fusion_plating_shopfloor/models/res_users.py
+++ b/fusion_plating/fusion_plating_shopfloor/models/res_users.py
@@ -139,3 +139,50 @@ class ResUsers(models.Model):
             'name': 'Set Tablet PIN',
             'target': 'new',
         }
+
+    def _check_credentials(self, credential, env):
+        """Custom auth manager: accept `type='fp_tablet_pin'` credential.
+
+        Validates the PIN hash, that the user is active, and that they hold
+        at least one shop-branch plating role. On success, returns the auth
+        info dict Odoo's session expects. On failure, raises AccessDenied
+        so the standard auth chain returns a 401.
+
+        See docs/superpowers/specs/2026-05-24-tablet-pin-session-redesign-design.md
+        Section 2 — Auth path.
+        """
+        from odoo.exceptions import AccessDenied
+        if isinstance(credential, dict) and credential.get('type') == 'fp_tablet_pin':
+            login = credential.get('login')
+            pin = credential.get('pin')
+            if not login or not pin:
+                raise AccessDenied()
+            user_sudo = self.sudo().search([('login', '=', login)], limit=1)
+            if not user_sudo or not user_sudo.active:
+                raise AccessDenied()
+            # Must hold a shop-branch role (otherwise they can't operate the tablet)
+            shop_branch_xmlids = (
+                'fusion_plating.group_fp_technician',
+                'fusion_plating.group_fp_shop_manager_v2',
+                'fusion_plating.group_fp_manager',
+                'fusion_plating.group_fp_quality_manager',
+                'fusion_plating.group_fp_owner',
+            )
+            shop_branch_ids = {
+                g.id for g in (
+                    self.env.ref(x, raise_if_not_found=False)
+                    for x in shop_branch_xmlids
+                ) if g
+            }
+            user_group_ids = set(user_sudo.group_ids.ids)
+            if not (shop_branch_ids & user_group_ids):
+                raise AccessDenied()
+            # Verify the PIN hash. verify_tablet_pin already exists.
+            if not user_sudo.verify_tablet_pin(pin):
+                raise AccessDenied()
+            return {
+                'uid': user_sudo.id,
+                'auth_method': 'fp_tablet_pin',
+                'mfa': 'default',
+            }
+        return super()._check_credentials(credential, env)