⚠️ Experimental endpoint — not yet a stable contract. This resource ships as experimental / beta. While experimental, its schema and behaviour may change without a version bump — including breaking changes within v2.0 itself. Anyone consuming it does so for evaluation only, or by coordinating adoption with their account manager so changes can be sequenced with them. It graduates to a stable, version-locked contract (where the normal breaking-change rules apply) only when this experimental notice is removed.

Partially edit a scheduled or active change under the current stored state. Omitted properties are preserved; only endsAt and note can be cleared with null. Unchanged active start and discount values are accepted. An empty or semantically identical edit leaves timestamps, actor, reason and audit unchanged, even when a scheduled start is due but not processed. Effective edits record the administrator and clear the automatic reason. Invalid supplied fields, conditional revert combinations and clearing an active end return 422 with API field names. For effective edits, an invalid startsAt or endsAt supplied in the request returns 422; when only an omitted stored timestamp blocks the edit, the response is 409 without field-validation errors. If both supplied and omitted timestamps fail validation, the supplied-field errors return 422. Disabled billing, terminal states and changed active start or discount return 409. Overlap returns 409 with message Another scheduled discount change already covers this period.

Required permission: Partners.update on the visible parent partner. Missing, out-of-scope or wrong-parent identifiers return 404; a visible partner without edit permission returns 403.