The Payroll app no longer shows an error when users open the Payslips menu before any payslips have been created. This prevents an unnecessary interruption and lets payroll users access the menu normally in a new or empty payroll setup.

Related task: 4919933

Belgian payroll termination holiday reports now use the exercise and holiday period from the payslip instead of the employee contract. This helps ensure the reported values match the actual payslip, reducing payroll reporting errors.

The exercise and the holiday period should be based on the payslip instead of the contract.

We use the values of the report report_termination_holidays_n and report_termination_holidays_n1 which contains the correct values.

Forward-Port-Of: odoo/enterprise#89171
Forward-Port-Of: odoo/enterprise#88737

This fix stops users from accidentally creating open planning shifts from the calendar view when no resource is selected. It removes leftover behavior from an earlier multi-create implementation, helping keep schedules accurate and avoiding unassigned work entries.

This commit's purpose is to prevent the creation of open shifts in the calendar view of the planning. Recently, the multi-create feature was added to the calendar view, but some code of the early iteration of the task was left. This fix aim to remove the unneeded code.

target saas-18.4

Forward-Port-Of: odoo/enterprise#89531

Belgian payroll follow-up activities are now generated when an employee contract actually becomes active, rather than repeatedly during later contract updates. This prevents unnecessary duplicate reminders and helps payroll teams focus on the correct next actions.

Once the contract got running, not at each write on it.

Forward-Port-Of: odoo/enterprise#89497

This fixes an issue where highlighted shifts in Planning calendars could lose their visual emphasis after an underlying calendar method changed. Business users will again see important shifts clearly marked in the schedule, helping them spot relevant planning information quickly.

Before this commit, the PlanningCalendarCommonRenderer override the eventToRender method but this method has been removed in parent class.

This commit changes the method overriden to make sure the class is added when some shifts have to be highlighted.

Forward-Port-Of: odoo/enterprise#81770