feat(scheduling): persist candidate slot ordering

src/govoplan_scheduling/backend/service.py

@@ -20,6 +20,7 @@ from govoplan_core.core.poll import (
     PollAnswerRequest,
     PollCapabilityError,
     PollCreateCommand,
+    PollOptionOrderCommand,
     PollOptionUpdateCommand,
     PollOptionRequest,
     PollResponseRef,
@@ -207,7 +208,10 @@ def _poll_status_for_request(status: str) -> str:
 
 
 def _active_slots(request: SchedulingRequest) -> list[SchedulingCandidateSlot]:
-    return [slot for slot in request.slots if slot.deleted_at is None]
+    return sorted(
+        (slot for slot in request.slots if slot.deleted_at is None),
+        key=lambda slot: (slot.position, slot.id),
+    )
 
 
 def _active_participants(request: SchedulingRequest) -> list[SchedulingParticipant]:
@@ -2397,35 +2401,6 @@ def _candidate_slot_changes_from_reconcile(
     )
 
 
-def _validate_slot_reconciliation_order(
-    current_slots: list[SchedulingCandidateSlot],
-    supplied_slots: list[SchedulingCandidateSlotReconcileInput],
-) -> None:
-    supplied_existing_ids = [item.id for item in supplied_slots if item.id is not None]
-    retained_ids = {
-        item.id
-        for item in supplied_slots
-        if item.id is not None
-    }
-    expected_existing_ids = [
-        slot.id
-        for slot in current_slots
-        if slot.id in retained_ids
-    ]
-    if supplied_existing_ids != expected_existing_ids:
-        raise SchedulingError(
-            "Existing candidate slots cannot be reordered; retain their order and append new slots"
-        )
-    encountered_new = False
-    for item in supplied_slots:
-        if item.id is None:
-            encountered_new = True
-        elif encountered_new:
-            raise SchedulingError(
-                "New candidate slots must be appended after existing slots"
-            )
-
-
 def _reconcile_scheduling_slots(
     session: Session,
     *,
@@ -2449,7 +2424,6 @@ def _reconcile_scheduling_slots(
     )
     if unknown_ids:
         raise SchedulingError("Unknown scheduling candidate slot")
-    _validate_slot_reconciliation_order(current_slots, supplied_slots)
 
     supplied_ids = {
         item.id
@@ -2514,6 +2488,7 @@ def _reconcile_scheduling_slots(
         )
 
     participation_provider = _poll_participation_provider()
+    created_slots: list[SchedulingCandidateSlot] = []
     for item in new_inputs:
         changes = _candidate_slot_changes_from_reconcile(request, item)
         slot = SchedulingCandidateSlot(
@@ -2557,6 +2532,7 @@ def _reconcile_scheduling_slots(
             raise SchedulingError(str(exc)) from exc
         slot.poll_option_id = created.id
         slot.position = created.position
+        created_slots.append(slot)
 
     for slot in removed_slots:
         if participation_provider is None:  # Guarded above; keeps type narrowing explicit.
@@ -2574,7 +2550,40 @@ def _reconcile_scheduling_slots(
             raise SchedulingError(str(exc)) from exc
         slot.deleted_at = _now()
 
-    return bool(planned_updates or new_inputs or removed_slots)
+    created_iter = iter(created_slots)
+    ordered_slots = [
+        current_by_id[item.id] if item.id is not None else next(created_iter)
+        for item in supplied_slots
+    ]
+    if any(slot.poll_option_id is None for slot in ordered_slots):
+        raise SchedulingError("Scheduling slot has no backing poll option")
+    position_changed = any(
+        slot.position != position
+        for position, slot in enumerate(ordered_slots)
+    )
+    try:
+        _poll_provider().reorder_options(
+            session,
+            tenant_id=request.tenant_id,
+            poll_id=request.poll_id,
+            command=PollOptionOrderCommand(
+                option_ids=tuple(
+                    cast(str, slot.poll_option_id)
+                    for slot in ordered_slots
+                ),
+            ),
+        )
+    except PollCapabilityError as exc:
+        raise SchedulingError(str(exc)) from exc
+    for position, slot in enumerate(ordered_slots):
+        slot.position = position
+
+    return bool(
+        planned_updates
+        or new_inputs
+        or removed_slots
+        or position_changed
+    )
 
 
 def _normalized_participant_identity(value: str | None) -> str | None: