chore: save current workspace progress

ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/SequentialLongitudinalOptimizer.cs

@@ -119,6 +119,8 @@ public sealed class SequentialLongitudinalOptimizer
                     settings.EnablePolishing,
                     settings.EnableNativeVerboseOutput),
                 warmStart, cancellationToken);
+            if (cancellationToken.IsCancellationRequested)
+                return Failed(EmPlanningStatus.Cancelled, "Longitudinal optimization was cancelled after the QP solve.");
             if (solved == null)
                 return FallbackOrFailure(lastStrictCandidate, EmPlanningStatus.Failed, "The longitudinal QP solver returned no result.");
             if (solved.Status == QpSolveStatus.TimeLimit || solved.Status == QpSolveStatus.MaximumIterations)
@@ -293,6 +295,12 @@ public sealed class SequentialLongitudinalOptimizer
                     settings.EnablePolishing, settings.EnableNativeVerboseOutput),
                 ToPrimal(linearizationIterate), cancellationToken);
             projectionSolveCount++;
+            if (cancellationToken.IsCancellationRequested)
+            {
+                failureStatus = EmPlanningStatus.Cancelled;
+                failureReason = WithStaticSeedDiagnostic("Initial full-direction feasibility projection was cancelled after the QP solve.");
+                return false;
+            }
             if (solved == null)
             {
                 failureStatus = EmPlanningStatus.Failed;
@@ -1196,7 +1204,7 @@ public sealed class SequentialLongitudinalOptimizer
     private static LongitudinalPlanningResult FallbackOrFailure(LongitudinalCandidate candidate,
         EmPlanningStatus failureStatus, string failureReason)
     {
-        return candidate == null
+        return failureStatus == EmPlanningStatus.Cancelled || candidate == null
             ? Failed(failureStatus, failureReason)
             : new LongitudinalPlanningResult(EmPlanningStatus.SuccessWithFallback, candidate, failureReason);
     }