Updates one of an employee's time off policy assignments using JSON Merge Patch semantics: a field left out of the body keeps its current value, and at least one of policyId and effectiveDate must be present. policyId reassigns the employee to another policy in the same time off category; reassigning to a policy in a different category is rejected, since that is an assignment for the other category and is created with POST. effectiveDate moves the date the assignment takes effect (the accrual basis date for accruing policies); it must not precede the employee's hire date, and on an assignment that has already ended it must not pass the end date. endDate is server managed and not accepted. The change is recorded the way the admin UI records it: the addressed assignment is kept as an audit copy with status SUPERSEDED and a new assignment carrying the requested policy and effective date takes its place, so the response's id differs from assignmentId whenever something changed. The superseded assignment keeps its own dates; it is an audit copy. The employee holds at most one assignment per category at any point in time and this call keeps that true: an assignment in the category that starts on or after the new effective date and no later than this assignment's end date is archived (no longer in effect, kept as history, whether or not it had already taken effect), and the assignment that preceded this one is re-ended at the day before the new effective date. Assignments that start after this one ends are not affected. Everything the call changed, the superseded assignment included, is returned in supersededAssignments in its post-write state; archived assignments are not listed anywhere else. Accruals for the category are recalculated from the earliest date the change affects. A body whose values equal the assignment's current values would change nothing and is refused with 409, as on assign. Accepts both application/merge-patch+json and application/json.

OAuth Scopes: time_off:policies.write