From 05610411b10f3d4f097ec534011acbbe4a9a766b Mon Sep 17 00:00:00 2001
From: Marius Merschformann <marius.merschformann@gmail.com>
Date: Thu, 6 Nov 2025 14:38:13 +0100
Subject: [PATCH 1/2] Avoiding unplanning of units units for vehicle and island
 heuristics

---
 solve_operator_unplan.go | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/solve_operator_unplan.go b/solve_operator_unplan.go
index e23836fa..b09718c7 100644
--- a/solve_operator_unplan.go
+++ b/solve_operator_unplan.go
@@ -168,6 +168,12 @@ func (d *solveOperatorUnPlanImpl) unplanOneIsland(
 	numberOfStops int,
 ) (int, error) {
 	planUnit := solution.PlannedPlanUnits().RandomElement()
+
+	// Reject island unplanning if it's a units-unit.
+	if isUnitsUnit(planUnit) {
+		return 0, nil
+	}
+
 	planStopsUnit := common.RandomElement(solution.Random(), planUnit.PlannedPlanStopsUnits())
 	for _, solutionStop := range planStopsUnit.(*solutionPlanStopsUnitImpl).solutionStops {
 		return d.unplanOneStopIsland(
@@ -222,10 +228,23 @@ func (d *solveOperatorUnPlanImpl) unplanSomeStopsOfOneVehicle(
 
 	for _, stop := range stops {
 		if stop.IsPlanned() && !stop.IsFixed() {
+			// TODO: should this be inverted (our chance is 0.2, so 80% chance
+			// to unplan - a.k.a. NOT skip unplanning)?
 			if solution.Random().Float64() < chance {
 				continue
 			}
-			unplanned, err := stop.PlanStopsUnit().UnPlan()
+
+			planStopsUnit := stop.PlanStopsUnit()
+
+			// // Get parent of unit to unplan full units.
+			// planStopsUnit := solution.PlannedPlanUnits().SolutionPlanUnit(stop.modelStop().planUnit)
+
+			// Reject unplanning if it's a units-unit.
+			if isUnitsUnit(planStopsUnit) {
+				continue
+			}
+
+			unplanned, err := planStopsUnit.UnPlan()
 			if err != nil {
 				return 0, err
 			}

From ba03513f6754d4b2b778341b647b596598000620 Mon Sep 17 00:00:00 2001
From: Marius Merschformann <marius.merschformann@gmail.com>
Date: Thu, 6 Nov 2025 14:42:31 +0100
Subject: [PATCH 2/2] Adding type check helper func

---
 solve_operator_unplan.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/solve_operator_unplan.go b/solve_operator_unplan.go
index b09718c7..136f5e56 100644
--- a/solve_operator_unplan.go
+++ b/solve_operator_unplan.go
@@ -290,3 +290,13 @@ func (d *solveOperatorUnPlanImpl) unplanLocation(
 
 	return count, nil
 }
+
+func isUnitsUnit(plannedPlanUnit SolutionPlanUnit) bool {
+	switch plannedPlanUnit.(type) {
+	case SolutionPlanStopsUnit:
+		return false
+	case SolutionPlanUnitsUnit:
+		return true
+	}
+	panic("unknown solution plan unit type")
+}