fix(farm_qbo_connection): implement action_refresh_token referenced by form view

The form view's header declared a `Refresh Token` button (visible when
state ∈ {connected, expired}) calling `action_refresh_token`, but the
model never shipped the method. Odoo's view validator caught it at
install time:

  ParseError: while parsing farm_qbo_connection_views.xml:25
    action_refresh_token is not a valid action on farm.qbo.connection

Adds the method on the model and the underlying token-refresh round-trip
on services/intuit_client.IntuitClient.refresh_access_token() — uses
intuitlib.client.AuthClient.refresh() when the libs are installed, raises
a clear UserError in stub mode. Two tests cover both paths: missing
refresh token → UserError; mocked successful refresh → connection record
updated with new access/refresh tokens + expiry.

Unblocks CI on PR #1 and the entire stacked PR chain (#2–#6) that
targets feature branches off this one.

Author: dnplkndll

farm_quickbooks_io/models/farm_qbo_connection.py

@@ -1,4 +1,7 @@
+from datetime import timedelta
+
 from odoo import api, fields, models
+from odoo.exceptions import UserError
 
 
 class FarmQboConnection(models.Model):
@@ -94,3 +97,58 @@ def action_disconnect(self):
                 "realm_id": False,
             }
         )
+
+    def action_refresh_token(self):
+        """Mint a fresh access token using the stored refresh token.
+
+        Called from the form-view header button when state ∈ {connected,
+        expired}. Delegates the actual round-trip to the intuit-oauth
+        library via `services.intuit_client.IntuitClient`; bails with a
+        clear UserError if either the refresh token is missing or the
+        intuit-oauth libs aren't installed (stub mode).
+        """
+        self.ensure_one()
+        if not self.refresh_token:
+            raise UserError(
+                self.env._(
+                    "No refresh token stored. Click Connect QuickBooks to "
+                    "complete the OAuth flow first."
+                )
+            )
+        # Lazy import keeps stub-mode installs (no intuit-oauth wheel) from
+        # crashing at module-load time.
+        from ..services.intuit_client import (  # noqa: PLC0415
+            HAS_INTUIT_LIBS,
+            IntuitClient,
+        )
+
+        if not HAS_INTUIT_LIBS:
+            raise UserError(
+                self.env._(
+                    "intuit-oauth library is not installed. Install "
+                    "`intuit-oauth` + `python-quickbooks` to refresh tokens."
+                )
+            )
+        client = IntuitClient(self)
+        new_tokens = client.refresh_access_token()
+        self.write(
+            {
+                "access_token": new_tokens["access_token"],
+                "refresh_token": new_tokens.get("refresh_token", self.refresh_token),
+                "token_expires_at": fields.Datetime.now()
+                + timedelta(seconds=new_tokens.get("expires_in", 3600)),
+            }
+        )
+        return {
+            "type": "ir.actions.client",
+            "tag": "display_notification",
+            "params": {
+                "type": "success",
+                "title": self.env._("Token refreshed"),
+                "message": self.env._(
+                    "New access token valid until %s.",
+                    self.token_expires_at,
+                ),
+                "next": {"type": "ir.actions.act_window_close"},
+            },
+        }

farm_quickbooks_io/services/intuit_client.py

@@ -33,6 +33,31 @@ def is_live(self):
             self.connection.access_token and self.connection.realm_id
         )
 
+    def refresh_access_token(self):
+        """Exchange the stored refresh token for a fresh access token.
+
+        Returns a dict matching Intuit's token response shape:
+        ``{access_token, refresh_token, expires_in, x_refresh_token_expires_in}``.
+        Caller writes the values back onto the farm.qbo.connection record.
+        """
+        if not HAS_INTUIT_LIBS:
+            raise RuntimeError(
+                "intuit-oauth not installed; cannot refresh access token."
+            )
+        auth = AuthClient(
+            client_id="STUB",  # configured via ir.config_parameter in v1
+            client_secret="STUB",
+            environment=self.connection.environment,
+            redirect_uri="https://localhost/farm_qbo/oauth/callback",
+        )
+        auth.refresh_token = self.connection.refresh_token
+        auth.refresh()
+        return {
+            "access_token": auth.access_token,
+            "refresh_token": auth.refresh_token,
+            "expires_in": auth.expires_in,
+        }
+
     def _real_client(self):
         if not HAS_INTUIT_LIBS:
             raise RuntimeError(

farm_quickbooks_io/tests/test_farm_qbo.py

@@ -1,3 +1,6 @@
+from unittest.mock import patch
+
+from odoo.exceptions import UserError
 from odoo.tests.common import TransactionCase
 
 
@@ -74,6 +77,38 @@ def test_import_rollback_reverses_commit(self):
         for m in imp.mapping_ids:
             self.assertFalse(m.committed_target_ref)
 
+    def test_action_refresh_token_without_refresh_token_raises(self):
+        # Connection with no refresh token can't refresh — must bail with a
+        # clear UserError rather than calling out to Intuit with None.
+        with self.assertRaises(UserError):
+            self.connection.action_refresh_token()
+
+    def test_action_refresh_token_writes_new_access_token(self):
+        # Stub IntuitClient.refresh_access_token so the test doesn't need the
+        # intuit-oauth wheel installed; verify the connection record is
+        # updated with the new tokens.
+        self.connection.write({"access_token": "old", "refresh_token": "rt"})
+        new_tokens = {
+            "access_token": "new-access",
+            "refresh_token": "new-refresh",
+            "expires_in": 3600,
+        }
+        with (
+            patch(
+                "odoo.addons.farm_quickbooks_io.services.intuit_client.HAS_INTUIT_LIBS",
+                True,
+            ),
+            patch(
+                "odoo.addons.farm_quickbooks_io.services."
+                "intuit_client.IntuitClient.refresh_access_token",
+                return_value=new_tokens,
+            ),
+        ):
+            self.connection.action_refresh_token()
+        self.assertEqual(self.connection.access_token, "new-access")
+        self.assertEqual(self.connection.refresh_token, "new-refresh")
+        self.assertTrue(self.connection.token_expires_at)
+
     def test_wizard_creates_and_starts_import(self):
         Wizard = self.env["farm.qbo.import.wizard"]
         wiz = Wizard.create(