feat(planner): implement cancellation for planning calculations

- Refactor leave-planner.worker.ts to support cancellation of ongoing calculations.
- Introduce `calculatePlanningAsyncInternal` for asynchronous planning calculations.
- Add cancellation handling in the worker message event.
- Update planning-date.ts with new utility functions for date manipulation.
- Extend translation-service.ts and translation files (en.json, de.json, es.json, fr.json) to include new strings related to planning horizon and cancellation.
- Create documentation for the cancellation feature in planner-cancellation.md.
- Add unit tests for cancellation functionality in leave-planner-cancellation.spec.ts and leave-planner.worker.spec.ts.

#57 #58

src/app/services/leave-planner.worker.ts

@@ -15,7 +15,7 @@ import type {
 } from './leave-planner.service';
 import {
 	analyzeCounterfactualInternal,
-	calculatePlanningInternal,
+	calculatePlanningAsyncInternal,
 	explainIncompleteCheckpoint,
 	historicalCounterfactualReasons,
 	type CounterfactualBaselineOptions,
@@ -38,6 +38,7 @@ type WorkerRequest =
 			request: WorkerPlanningRequest;
 	  }
 	| { type: 'trace-ack'; count: number }
+	| { type: 'cancel' }
 	| {
 			type: 'counterfactual';
 			request: PlanningSnapshot;
@@ -120,6 +121,7 @@ interface TraceDelivery {
 }
 
 let activeTraceDelivery: TraceDelivery | undefined;
+let activeCalculation: { cancelled: boolean } | undefined;
 
 function traceStatusIndex(trace: PlanningTrace): {
 	statuses: Map<string, TraceCandidateStatus>;
@@ -272,8 +274,12 @@ function pumpTraceUpdates(delivery: TraceDelivery): void {
 	finishTraceDelivery(delivery);
 }
 
-worker.onmessage = (event: MessageEvent<WorkerRequest>) => {
+worker.onmessage = async (event: MessageEvent<WorkerRequest>) => {
 	try {
+		if (event.data?.type === 'cancel') {
+			if (activeCalculation) activeCalculation.cancelled = true;
+			return;
+		}
 		if (event.data?.type === 'trace-ack') {
 			const delivery = activeTraceDelivery;
 			if (!delivery || !Number.isInteger(event.data.count) || event.data.count <= 0) return;
@@ -282,6 +288,8 @@ worker.onmessage = (event: MessageEvent<WorkerRequest>) => {
 			return;
 		}
 		if (event.data?.type === 'plan') {
+			const calculation = { cancelled: false };
+			activeCalculation = calculation;
 			let artifacts: PlanningArtifacts = {};
 			let outcomePosted = false;
 			let outcome: PlanningOutcome;
@@ -294,7 +302,7 @@ worker.onmessage = (event: MessageEvent<WorkerRequest>) => {
 			};
 			activeTraceDelivery = traceDelivery;
 			try {
-				outcome = calculatePlanningInternal(
+				outcome = await calculatePlanningAsyncInternal(
 					{
 						...event.data.request,
 						progress: (stage: string) =>
@@ -331,6 +339,7 @@ worker.onmessage = (event: MessageEvent<WorkerRequest>) => {
 							explanationError,
 							finalState,
 						} satisfies WorkerResponse),
+					() => calculation.cancelled,
 				);
 			} catch (error) {
 				if (activeTraceDelivery === traceDelivery) activeTraceDelivery = undefined;
@@ -341,6 +350,8 @@ worker.onmessage = (event: MessageEvent<WorkerRequest>) => {
 					message: error instanceof Error ? error.message : String(error),
 				} satisfies WorkerResponse);
 				return;
+			} finally {
+				if (activeCalculation === calculation) activeCalculation = undefined;
 			}
 			if (!outcomePosted)
 				worker.postMessage({ type: 'result', outcome } satisfies WorkerResponse);