vac-optimizer/src/app/services/leave-planner.service.spec.ts

import { vi } from 'vitest';
import {
	applyReplayDeltas,
	PlanningOutcome,
	PlanningRequest,
	createPlanningCalculation,
	planLeave,
} from './leave-planner.service';
import type {
	CounterfactualAnalysis,
	HistoricalEligibilityReason,
	PlanOutcome,
	PlanningReason,
	PlanningTraceState,
	PlanningTraceUpdate,
} from './leave-planner.service';
import type { CounterfactualBaselineOptions } from './leave-planner.core';

const horizon = { start: '2024-01-01', end: '2025-01-01' };
const balance = (
	id: string,
	type: 'cp' | 'rtt' | 'other',
	quantity: number,
	expiryDate = '2024-12-31',
) => ({
	id,
	type,
	quantity,
	availableFrom: '2024-01-01',
	expiryDate,
});

function isPlan(outcome: PlanningOutcome) {
	if (outcome.kind !== 'Plan') throw new Error(`Expected plan, got ${outcome.kind}`);
	return outcome;
}

async function runInNonBrowser(request: Parameters<typeof planLeave>[0]) {
	const browserWindow = globalThis.window;
	vi.stubGlobal('window', undefined);
	try {
		return await planLeave(request);
	} finally {
		vi.stubGlobal('window', browserWindow);
	}
}

beforeEach(() => vi.setSystemTime(new Date('2024-01-01T12:00:00Z')));
afterEach(() => vi.useRealTimers());

describe('calculated work-sequence and time-off-period statistics', () => {
	it('keeps fractional work means and merges consecutive declared days across a weekend', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-11' },
				balances: [],
				rules: [],
				declaredDays: ['2024-01-05', '2024-01-08'].map((date) => ({
					date,
					type: 'other',
				})),
			}),
		);
		expect(result.metrics).toMatchObject({
			nonWorkingDayGain: 2,
			averageWorkSequence: 2.5,
			longestWorkSequence: 3,
			averageTimeOffPeriod: 4,
			longestTimeOffPeriod: 4,
		});
	});

	it.each([
		{
			scenario: 'averages the 10, 5 and 15 working days including both horizon edges',
			horizon: { start: '2024-01-08', end: '2024-02-21' },
			declaredDates: ['2024-01-22', '2024-01-30'],
			metrics: {
				averageWorkSequence: 10,
				longestWorkSequence: 15,
				averageTimeOffPeriod: 2,
				longestTimeOffPeriod: 3,
				nonWorkingDayGain: 2,
			},
		},
		{
			scenario: 'keeps the unrounded mean of work sequences of 3, 1 and 6 days',
			horizon: { start: '2024-01-02', end: '2024-01-18' },
			declaredDates: ['2024-01-05', '2024-01-09'],
			metrics: {
				averageWorkSequence: 10 / 3,
				longestWorkSequence: 6,
				averageTimeOffPeriod: 2,
				longestTimeOffPeriod: 3,
				nonWorkingDayGain: 2,
			},
		},
		{
			scenario: 'averages one-day and two-day breaks without adding zero-length work samples',
			horizon: { start: '2024-01-02', end: '2024-01-12' },
			declaredDates: ['2024-01-03', '2024-01-09', '2024-01-10'],
			metrics: {
				averageWorkSequence: 5 / 3,
				longestWorkSequence: 3,
				averageTimeOffPeriod: 1.5,
				longestTimeOffPeriod: 2,
				nonWorkingDayGain: 0,
			},
		},
		{
			scenario: 'does not count or split work on intervening holidays and weekends',
			horizon: { start: '2024-05-06', end: '2024-05-15' },
			declaredDates: [],
			metrics: {
				averageWorkSequence: 5,
				longestWorkSequence: 5,
				averageTimeOffPeriod: null,
				longestTimeOffPeriod: null,
				nonWorkingDayGain: 0,
			},
		},
		{
			scenario:
				'retains an empty work average and a measured zero when every workday is declared',
			horizon: { start: '2024-01-08', end: '2024-01-13' },
			declaredDates: ['2024-01-08', '2024-01-09', '2024-01-10', '2024-01-11', '2024-01-12'],
			metrics: {
				averageWorkSequence: null,
				longestWorkSequence: 0,
				averageTimeOffPeriod: 9,
				longestTimeOffPeriod: 9,
				nonWorkingDayGain: 4,
			},
		},
		{
			scenario: 'distinguishes no samples from zero gain in a weekend-only horizon',
			horizon: { start: '2024-01-06', end: '2024-01-08' },
			declaredDates: [],
			metrics: {
				averageWorkSequence: null,
				longestWorkSequence: 0,
				averageTimeOffPeriod: null,
				longestTimeOffPeriod: null,
				nonWorkingDayGain: 0,
			},
		},
		{
			scenario:
				'counts Christmas on a Saturday once alongside its Sunday in a declared break',
			horizon: { start: '2021-12-20', end: '2021-12-28' },
			declaredDates: ['2021-12-24'],
			metrics: {
				averageWorkSequence: 2.5,
				longestWorkSequence: 4,
				averageTimeOffPeriod: 3,
				longestTimeOffPeriod: 3,
				nonWorkingDayGain: 2,
			},
		},
	])('$scenario', async ({ horizon, declaredDates, metrics }) => {
		const result = isPlan(
			await runInNonBrowser({
				horizon,
				balances: [],
				rules: [],
				declaredDays: declaredDates.map((date) => ({ date, type: 'other' })),
			}),
		);
		expect(result.placements).toEqual([]);
		expect(result.metrics).toMatchObject(metrics);
	});
});

describe('declared holiday patterns and captured entitlement date', () => {
	const producer = {
		id: 'producer',
		type: 'if_then' as const,
		force: 'obligation' as const,
		dayOfWeek: 3,
		placement: 'before' as const,
		placeDays: 2,
		placeType: 'cp' as const,
		rewardDays: 1,
		rewardType: 'other' as const,
	};
	const fixed = ['2024-04-29', '2024-04-30'].map((date) => ({ date, type: 'cp' as const }));
	const request = {
		horizon: { start: '2024-04-29', end: '2024-05-08' },
		balances: [],
		rules: [producer],
		declaredDays: fixed,
	};

	it.each([
		['before', ['2024-04-29', '2024-04-30']],
		['after', ['2024-05-02', '2024-05-03']],
		['around', ['2024-04-30', '2024-05-02']],
		['auto', ['2024-04-29', '2024-04-30']],
	] as const)(
		'credits the normal %s pattern, fully declared or mixed, without duplicate TIME_WINDOW debits',
		async (placement, dates) => {
			for (const mixed of [false, true]) {
				const declaredDays = (mixed ? dates.slice(0, 1) : dates).map((date) => ({
					date,
					type: 'cp' as const,
				}));
				const result = isPlan(
					await runInNonBrowser({
						...request,
						declaredDays,
						balances: mixed ? [balance('cp', 'cp', 1, '2025-12-31')] : [],
						rules: [
							{ ...producer, placement, rewardDays: 0 },
							{
								id: 'shared',
								type: 'time_window',
								force: 'obligation',
								startDate: dates[0],
								endDate: dates[1],
								placeDays: 2,
								placeType: 'cp',
							},
						],
					}),
				);
				expect(result.placements.map(({ date }) => date)).toEqual(mixed ? [dates[1]] : []);
				expect(
					result.placements.every(
						({ ruleIds }) => ruleIds.includes('producer') && ruleIds.includes('shared'),
					),
				).toBe(true);
				expect(result.ifThenContributions).toMatchObject([
					{
						occurrence: '2024-05-01',
						declaredDays,
						placementDates: mixed ? [dates[1]] : [],
					},
				]);
				expect(result.declaredDays).toEqual(declaredDays);
			}
		},
	);

	it.each(['cp', 'rtt', 'other', 'any'] as const)(
		'accepts compatible %s declarations in an entirely fixed preference',
		async (placeType) => {
			const declaredDays = fixed.map((day, index) => ({
				...day,
				type:
					placeType === 'any'
						? index
							? ('other' as const)
							: ('rtt' as const)
						: placeType,
			}));
			const result = isPlan(
				await runInNonBrowser({
					...request,
					declaredDays,
					rules: [{ ...producer, force: 'preference', placeType }],
				}),
			);
			expect(result.preferences).toMatchObject([
				{ ruleId: 'producer', satisfied: 1, completeOccurrences: 1 },
			]);
			expect(result.placements).toEqual([]);
			expect(result.remainingBalances).toMatchObject([
				{
					id: 'earned:producer:2024-05-01',
					quantity: 1,
					availableFrom: '2024-05-02',
					expiryDate: '2025-05-02',
				},
			]);
		},
	);

	it('does not skip an incompatible normal position, complete a partial preference, or invent a holiday', async () => {
		const declaredDays = [fixed[0], { date: '2024-04-30', type: 'rtt' as const }];
		const conflict = await runInNonBrowser({
			...request,
			declaredDays,
			balances: [balance('cp', 'cp', 3)],
		});
		expect(conflict.kind).toBe('PlanningConflict');
		if (conflict.kind === 'PlanningConflict')
			expect(conflict.conflictingRuleIds).toContain('producer');
		const preference = isPlan(
			await runInNonBrowser({
				...request,
				declaredDays,
				rules: [{ ...producer, force: 'preference' }],
			}),
		);
		expect(preference.preferences[0].satisfied).toBe(0);
		expect(preference.remainingBalances).toEqual([]);
		const noHoliday = isPlan(
			await runInNonBrowser({
				...request,
				horizon: { start: '2024-05-13', end: '2024-05-17' },
				declaredDays: fixed.map(({ type }, index) => ({
					type,
					date: `2024-05-${13 + index}`,
				})),
			}),
		);
		expect(noHoliday.ifThenContributions).toBeUndefined();
		expect(noHoliday.remainingBalances).toEqual([]);
		expect(
			(
				await runInNonBrowser({
					...request,
					horizon: { start: '2024-04-30', end: '2024-05-08' },
				})
			).kind,
		).toBe('PlanningConflict');
	});

	it('reserves only the unfilled positions of future IF_THEN preferences', async () => {
		const result = isPlan(
			await runInNonBrowser({
				...request,
				balances: [
					balance('cp', 'cp', 1, '2025-12-31'),
					balance('rtt', 'rtt', 1, '2025-06-01'),
				],
				rules: [
					{
						id: 'any-first',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-05-06',
						endDate: '2024-05-06',
						placeDays: 1,
						placeType: 'any',
					},
					{ ...producer, force: 'preference', rewardDays: 0 },
					{
						id: 'rtt-last',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-05-07',
						endDate: '2024-05-07',
						placeDays: 1,
						placeType: 'rtt',
					},
				],
			}),
		);
		expect(result.preferences.map(({ satisfied }) => satisfied)).toEqual([1, 1, 1]);
		expect(result.placements).toMatchObject([
			{ date: '2024-05-06', type: 'cp' },
			{ date: '2024-05-07', type: 'rtt' },
		]);
	});

	it('requires every real occurrence and creates each rule/occurrence entitlement only once', async () => {
		const submitted = {
			...request,
			horizon: { start: '2024-04-29', end: '2024-05-10' },
			rules: [
				{ ...producer, placeDays: 1 },
				{ ...producer, id: 'second', placeDays: 1 },
			],
			declaredDays: [
				{ date: '2024-04-30', type: 'cp' as const },
				{ date: '2024-05-07', type: 'cp' as const },
			],
		};
		const result = isPlan(await runInNonBrowser(submitted));
		expect(result.remainingBalances.map(({ id }) => id).sort()).toEqual([
			'earned:producer:2024-05-01',
			'earned:producer:2024-05-08',
			'earned:second:2024-05-01',
			'earned:second:2024-05-08',
		]);
		expect(result.remainingBalances.every(({ quantity }) => quantity === 1)).toBe(true);
		expect(
			(
				await runInNonBrowser({
					...submitted,
					declaredDays: submitted.declaredDays.slice(0, 1),
				})
			).kind,
		).toBe('PlanningConflict');
	});

	it.each([
		['2024-05-01', true],
		['2024-05-02', false],
		['2024-05-03', false],
	] as const)(
		'adds only strictly future rights on %s, also for newly placed historical patterns',
		async (today, added) => {
			vi.setSystemTime(new Date(`${today}T12:00:00Z`));
			for (const declared of [true, false]) {
				const result = isPlan(
					await runInNonBrowser({
						...request,
						declaredDays: declared ? fixed : [],
						balances: declared ? [] : [balance('cp', 'cp', 2, '2025-12-31')],
					}),
				);
				expect(result.calculationDate).toBe(today);
				expect(result.remainingBalances.filter(({ earned }) => earned)).toHaveLength(
					added ? 1 : 0,
				);
				expect(result.ifThenContributions?.[0].earnedEntitlement).toMatchObject({
					added,
					availableFrom: '2024-05-02',
				});
			}
		},
	);

	it.each([
		['2024-01-01', '2024-05-03'],
		['2024-05-03', '2024-05-03'],
		['2024-05-03', '2024-04-29'],
	])(
		'reconciles an externally funded extension on %s with consumer starting %s and rejects a self-financing extension',
		async (today, consumerStart) => {
			vi.setSystemTime(new Date(`${today}T12:00:00Z`));
			const extender = {
				id: 'extend',
				type: 'time_window' as const,
				force: 'obligation' as const,
				startDate: '2024-05-02',
				endDate: '2024-05-02',
				placeDays: 1,
				placeType: 'cp' as const,
			};
			const result = isPlan(
				await runInNonBrowser({
					...request,
					declaredDays: [...fixed, { date: '2024-05-03', type: 'other' }],
					balances: [balance('cp', 'cp', 1, '2025-12-31')],
					rules: [
						producer,
						extender,
						{
							id: 'later',
							type: 'time_window',
							force: 'obligation',
							startDate: consumerStart,
							endDate: '2024-05-07',
							placeDays: 2,
							placeType: 'other',
						},
					],
				}),
			);
			expect(result.ifThenContributions?.[0].earnedEntitlement).toMatchObject({
				availableFrom: '2024-05-06',
				expiryDate: '2025-05-06',
			});
			expect(
				result.placements.find(({ balanceId }) => balanceId.startsWith('earned:'))?.date,
			).toBe('2024-05-07');
			const impossible = await runInNonBrowser({
				...request,
				declaredDays: [...fixed, { date: '2024-05-03', type: 'other' }],
				rules: [producer, { ...extender, placeType: 'other' }],
			});
			expect(impossible.kind).toBe('PlanningConflict');
		},
	);

	it.each(['2024-04-29', '2025-05-07'])(
		'reconciles a future entitlement expiry before its consumer starting %s',
		async (consumerStart) => {
			vi.setSystemTime(new Date('2024-04-28T12:00:00Z'));
			const { isWorkingPlanningDate } = await import('./declared-non-working-days');
			const { addPlanningDays } = await import('./planning-date');
			const declaredDays: import('./leave-planner.core').DeclaredNonWorkingDay[] = [...fixed];
			for (let date = '2024-05-03'; date <= '2025-05-05'; date = addPlanningDays(date, 1)) {
				if (isWorkingPlanningDate(date)) declaredDays.push({ date, type: 'rtt' });
			}
			const result = isPlan(
				await runInNonBrowser({
					...request,
					horizon: { start: '2024-04-29', end: '2025-05-08' },
					declaredDays,
					balances: [balance('cp', 'cp', 1, '2025-12-31')],
					rules: [
						{ ...producer, force: 'preference' },
						{
							id: 'consumer',
							type: 'time_window',
							force: 'obligation',
							startDate: consumerStart,
							endDate: '2025-05-07',
							placeDays: 1,
							placeType: 'other',
						},
						{
							id: 'extend',
							type: 'time_window',
							force: 'obligation',
							startDate: '2024-05-02',
							endDate: '2024-05-02',
							placeDays: 1,
							placeType: 'cp',
						},
					],
				}),
			);
			expect(result.placements).toMatchObject([
				{ date: '2024-05-02', balanceId: 'cp' },
				{
					date: '2025-05-07',
					balanceId: 'earned:producer:2024-05-01',
					ruleIds: ['consumer'],
				},
			]);
			expect(
				result.ifThenContributions?.find(
					({ ruleId, occurrence }) =>
						ruleId === 'producer' && occurrence === '2024-05-01',
				)?.earnedEntitlement,
			).toMatchObject({ availableFrom: '2025-05-06', expiryDate: '2026-05-06', added: true });
		},
	);

	it('funds a later IF_THEN obligation after an obligatory window extends a reported generator', async () => {
		vi.setSystemTime(new Date('2024-05-03T12:00:00Z'));
		const result = isPlan(
			await runInNonBrowser({
				...request,
				horizon: { start: '2024-04-29', end: '2024-05-11' },
				declaredDays: [...fixed, { date: '2024-05-03', type: 'other' }],
				balances: [balance('cp', 'cp', 1, '2025-12-31')],
				rules: [
					{ ...producer, force: 'preference' },
					{
						id: 'extend',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-02',
						endDate: '2024-05-02',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'consumer',
						type: 'if_then',
						force: 'obligation',
						dayOfWeek: 4,
						placement: 'after',
						placeDays: 1,
						placeType: 'other',
						rewardDays: 0,
					},
				],
			}),
		);
		expect(result.placements).toMatchObject([
			{ date: '2024-05-02', balanceId: 'cp', ruleIds: ['extend'] },
			{ date: '2024-05-10', balanceId: 'earned:producer:2024-05-01', ruleIds: ['consumer'] },
		]);
		expect(
			result.ifThenContributions?.find(
				({ ruleId, occurrence }) => ruleId === 'producer' && occurrence === '2024-05-01',
			)?.earnedEntitlement,
		).toMatchObject({ availableFrom: '2024-05-06', added: true });
	});

	it('compares a generating preference with an ordinary obligation solution before spending higher-priority leave', async () => {
		vi.setSystemTime(new Date('2024-04-28T12:00:00Z'));
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-04-29', end: '2024-05-07' },
				declaredDays: [{ date: '2024-04-30', type: 'rtt' }],
				balances: [
					balance('cp', 'cp', 1, '2025-12-31'),
					balance('rtt', 'rtt', 1, '2025-12-31'),
				],
				rules: [
					{
						id: 'mandatory',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-06',
						endDate: '2024-05-06',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'first',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-04-29',
						endDate: '2024-04-29',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						...producer,
						force: 'preference',
						placement: 'around',
						placeType: 'rtt',
						rewardType: 'cp',
					},
				],
			}),
		);
		expect(result.preferences.map(({ satisfied }) => satisfied)).toEqual([1, 1]);
		expect(result.placements.find(({ date }) => date === '2024-04-29')?.balanceId).toBe('cp');
		expect(result.placements.find(({ date }) => date === '2024-05-06')?.balanceId).toBe(
			'earned:producer:2024-05-01',
		);
		expect(result.ifThenContributions?.[0].earnedEntitlement).toMatchObject({
			availableFrom: '2024-05-03',
			added: true,
		});
	});

	it.each([false, true])(
		'chooses between competing generators in the original preference order (reversed: %s)',
		async (reversed) => {
			vi.setSystemTime(new Date('2024-04-28T12:00:00Z'));
			const producers = [
				{ ...producer, id: 'before', force: 'preference' as const },
				{
					...producer,
					id: 'after',
					force: 'preference' as const,
					placement: 'after' as const,
				},
			];
			if (reversed) producers.reverse();
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2024-04-29', end: '2024-05-11' },
					declaredDays: [
						{ date: '2024-04-29', type: 'cp' },
						{ date: '2024-05-03', type: 'cp' },
						{ date: '2024-05-06', type: 'other' },
					],
					balances: [balance('cp', 'cp', 1, '2025-12-31')],
					rules: [
						{
							id: 'consumer',
							type: 'time_window',
							force: 'obligation',
							startDate: '2024-05-10',
							endDate: '2024-05-10',
							placeDays: 1,
							placeType: 'other',
						},
						...producers,
					],
				}),
			);
			expect(
				result.preferences.map(({ ruleId, satisfied }) => ({ ruleId, satisfied })),
			).toEqual([
				{ ruleId: producers[0].id, satisfied: 1 },
				{ ruleId: producers[1].id, satisfied: 0 },
			]);
			expect(result.placements.find(({ type }) => type === 'cp')?.date).toBe(
				reversed ? '2024-05-02' : '2024-04-30',
			);
			expect(result.placements.find(({ date }) => date === '2024-05-10')?.balanceId).toBe(
				`earned:${producers[0].id}:2024-05-01`,
			);
			expect(
				result.ifThenContributions?.filter(({ earnedEntitlement }) => earnedEntitlement),
			).toHaveLength(1);
		},
	);

	it('keeps a future right usable on its expiry date and excludes comparisons before availability or after expiry', async () => {
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				...request,
				horizon: { start: '2024-04-29', end: '2025-05-07' },
				declaredDays: [fixed[1]],
				rules: [
					{ ...producer, force: 'preference', placeDays: 1 },
					{
						id: 'expiry-consumer',
						type: 'time_window',
						force: 'preference',
						startDate: '2025-05-02',
						endDate: '2025-05-02',
						placeDays: 1,
						placeType: 'other',
					},
				],
			});
			const result = isPlan(await calculation.outcome);
			const placement = result.placements.find(
				({ balanceId }) => balanceId === 'earned:producer:2024-05-01',
			);
			expect(placement?.date).toBe('2025-05-02');
			if (!placement)
				throw new Error('Expected the earned entitlement to fund its last valid date.');
			const comparison = await calculation.analyzeCounterfactual(placement);
			if (comparison.kind !== 'Counterfactual') throw new Error('Expected date comparisons.');
			expect(comparison.results.find(({ date }) => date === '2024-04-29')?.reason?.code).toBe(
				'unavailable',
			);
			expect(comparison.results.find(({ date }) => date === '2025-05-02')?.status).toBe(
				'eligible',
			);
			expect(comparison.results.find(({ date }) => date === '2025-05-05')?.reason?.code).toBe(
				'expired',
			);
		} finally {
			vi.unstubAllGlobals();
		}
	});

	it.each(['worker-unavailable', 'deadline', 'validation'])(
		'keeps the launch date in %s outcomes after midnight',
		async (failure) => {
			vi.stubGlobal('Worker', undefined);
			vi.setSystemTime(new Date('2024-05-01T21:59:59Z'));
			const calculation = createPlanningCalculation({
				...request,
				...(failure === 'deadline' ? { deadlineMs: -1 } : {}),
				...(failure === 'validation' ? { balances: [balance('invalid', 'cp', -1)] } : {}),
			});
			vi.setSystemTime(new Date('2024-05-01T22:00:01Z'));
			expect(calculation.snapshot.calculationDate).toBe('2024-05-01');
			expect(await calculation.outcome).toMatchObject({
				calculationDate: '2024-05-01',
				kind: failure === 'worker-unavailable' ? 'PlanningIncomplete' : 'InvalidInput',
			});
			vi.unstubAllGlobals();
		},
	);
	it('includes declared context beyond the horizon in the complete generator period', async () => {
		const result = isPlan(
			await runInNonBrowser({
				...request,
				horizon: { start: '2024-04-29', end: '2024-05-02' },
				declaredDays: [
					...fixed,
					{ date: '2024-05-02', type: 'rtt' },
					{ date: '2024-05-03', type: 'other' },
				],
			}),
		);
		expect(result.remainingBalances).toMatchObject([
			{ availableFrom: '2024-05-06', expiryDate: '2025-05-06' },
		]);
		expect(result.timeOffPeriods).toMatchObject([
			{
				end: '2024-05-05',
				declaredDates: ['2024-04-29', '2024-04-30', '2024-05-02', '2024-05-03'],
			},
		]);
	});

	it('captures Paris before the direct import wait and keeps snapshot, late artifacts and comparisons on that date', async () => {
		vi.stubGlobal('window', undefined);
		try {
			vi.setSystemTime(new Date('2024-05-01T21:59:59Z'));
			const calculation = createPlanningCalculation({
				...request,
				rules: [
					producer,
					{
						id: 'later',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-03',
						endDate: '2024-05-03',
						placeDays: 1,
						placeType: 'other',
					},
				],
			});
			expect(calculation.snapshot.calculationDate).toBe('2024-05-01');
			vi.setSystemTime(new Date('2024-05-01T22:00:01Z'));
			const result = isPlan(await calculation.outcome);
			expect(result.calculationDate).toBe('2024-05-01');
			expect(await calculation.explanation).toMatchObject({
				calculationDate: '2024-05-01',
				declaredDays: fixed,
				ifThenContributions: result.ifThenContributions,
			});
			const trace = await calculation.trace;
			expect(trace?.initialState.calculationDate).toBe('2024-05-01');
			const comparison = await calculation.analyzeCounterfactual(result.placements[0]);
			expect(comparison.kind).toBe('Counterfactual');
			if (comparison.kind === 'Counterfactual') {
				expect(
					comparison.results.find(({ date }) => date === '2024-04-30')?.reason?.code,
				).toBe('declared-day');
				expect(comparison.results.find(({ date }) => date === '2024-05-02')?.status).toBe(
					'ineligible',
				);
				expect(comparison.results.find(({ date }) => date === '2024-05-03')?.status).toBe(
					'eligible',
				);
			}
			const consumerDecision = trace?.phases
				.flatMap(({ decisions }) => decisions)
				.find(({ deltas }) =>
					deltas.some(({ placement }) => placement?.balanceId.startsWith('earned:')),
				);
			expect(consumerDecision).toBeDefined();
			if (consumerDecision)
				expect(
					(
						await calculation.analyzeCounterfactual({
							decisionId: consumerDecision.id,
							placement: result.placements[0],
						})
					).kind,
				).toBe('Counterfactual');
		} finally {
			vi.unstubAllGlobals();
		}
	});
});

describe('planLeave', () => {
	it.each([
		['obligation', false],
		['obligation', true],
		['preference', false],
		['preference', true],
	] as const)(
		'uses declared holiday-pattern CP to earn future Other leave for the remaining TIME_WINDOW day (producer: %s, mixed: %s)',
		async (force, mixed) => {
			vi.setSystemTime(new Date('2024-04-28T12:00:00Z'));
			try {
				const declaredDays = [
					...(mixed ? [] : [{ date: '2024-04-29', type: 'cp' as const }]),
					{ date: '2024-04-30', type: 'cp' as const },
					{ date: '2024-05-06', type: 'other' as const },
				];
				const result = isPlan(
					await runInNonBrowser({
						horizon: { start: '2024-04-29', end: '2024-05-07' },
						balances: mixed ? [balance('cp', 'cp', 1, '2025-12-31')] : [],
						declaredDays,
						rules: [
							{
								id: 'producer',
								type: 'if_then',
								force,
								dayOfWeek: 3,
								placement: 'before',
								placeDays: 2,
								placeType: 'cp',
								rewardDays: 1,
								rewardType: 'other',
							},
							{
								id: 'consumer',
								type: 'time_window',
								force: 'obligation',
								startDate: '2024-05-03',
								endDate: '2024-05-06',
								placeDays: 2,
								placeType: 'other',
							},
						],
					}),
				);
				expect(result.declaredDays).toEqual(declaredDays);
				expect(result.placements.filter(({ type }) => type === 'other')).toEqual([
					{
						date: '2024-05-03',
						type: 'other',
						balanceId: 'earned:producer:2024-05-01',
						ruleIds: ['consumer'],
						supporting: false,
					},
				]);
				expect(result.placements.filter(({ type }) => type === 'cp')).toHaveLength(
					mixed ? 1 : 0,
				);
				expect(result.remainingBalances).toEqual([]);
			} finally {
				vi.useRealTimers();
			}
		},
	);

	it.each(['obligation', 'preference'] as const)(
		'completes five CP days with four remaining CP and a fixed Wednesday CP (%s)',
		async (force) => {
			const declaredDays = [{ date: '2024-01-10', type: 'cp' as const }];
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2024-01-08', end: '2024-01-13' },
					balances: [balance('cp', 'cp', 4, '2024-01-12')],
					declaredDays,
					rules: [
						{
							id: 'week',
							type: 'time_window',
							force,
							startDate: '2024-01-08',
							endDate: '2024-01-12',
							placeDays: 5,
							placeType: 'cp',
						},
					],
				}),
			);
			expect(result.declaredDays).toEqual(declaredDays);
			expect(result.placements.map(({ date }) => date)).toEqual([
				'2024-01-08',
				'2024-01-09',
				'2024-01-11',
				'2024-01-12',
			]);
			expect(result.placements.every(({ ruleIds }) => ruleIds.includes('week'))).toBe(true);
			expect(result.remainingBalances).toEqual([]);
			expect(result.timeWindowContributions).toEqual([
				{
					ruleId: 'week',
					label: 'week',
					requested: 5,
					declaredDays,
					placementDates: result.placements.map(({ date }) => date),
				},
			]);
			if (force === 'preference')
				expect(result.preferences).toMatchObject([{ requested: 5, satisfied: 5 }]);
		},
	);

	it.each(['cp', 'rtt', 'other'] as const)(
		'shares a fixed %s day between typed and ANY obligations and preferences without a balance',
		async (type) => {
			const declaredDays = [{ date: '2024-01-10', type }];
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2024-01-08', end: '2024-01-13' },
					balances: [],
					declaredDays,
					rules: (['obligation', 'preference'] as const).flatMap((force) =>
						([type, 'any'] as const).map((placeType) => ({
							id: `${force}-${placeType}`,
							type: 'time_window',
							force,
							startDate: '2024-01-08',
							endDate: '2024-01-12',
							placeDays: 1,
							placeType,
						})),
					),
				}),
			);
			expect(result.placements).toEqual([]);
			expect(result.remainingBalances).toEqual([]);
			expect(result.declaredDays).toEqual(declaredDays);
			expect(result.preferences.map(({ satisfied }) => satisfied)).toEqual([1, 1]);
			expect(result.metrics.preferenceSatisfaction).toEqual([1, 1]);
			expect(result.timeWindowContributions).toHaveLength(4);
			for (const contribution of result.timeWindowContributions ?? [])
				expect(contribution).toMatchObject({
					requested: 1,
					declaredDays,
					placementDates: [],
				});
		},
	);

	it('caps each rule contribution at its quantity while preserving every surplus declaration', async () => {
		const declaredDays = [
			{ date: '2024-01-10', type: 'cp' as const },
			{ date: '2024-01-08', type: 'cp' as const },
			{ date: '2024-01-09', type: 'cp' as const },
		];
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-08', end: '2024-01-13' },
				balances: [],
				declaredDays,
				rules: [
					{ id: 'exact', force: 'obligation', placeDays: 2, placeType: 'cp' },
					{ id: 'preferred', force: 'preference', placeDays: 1, placeType: 'any' },
				].map((rule) => ({
					...rule,
					type: 'time_window',
					startDate: '2024-01-08',
					endDate: '2024-01-12',
				})),
			}),
		);
		expect(result.declaredDays).toEqual(declaredDays);
		expect(result.placements).toEqual([]);
		expect(result.preferences).toMatchObject([{ requested: 1, satisfied: 1 }]);
		expect(result.timeWindowContributions).toMatchObject([
			{
				ruleId: 'exact',
				requested: 2,
				declaredDays: [declaredDays[1], declaredDays[2]],
				placementDates: [],
			},
			{
				ruleId: 'preferred',
				requested: 1,
				declaredDays: [declaredDays[1]],
				placementDates: [],
			},
		]);
	});

	it('credits inclusive window endpoints only inside the submitted half-open horizon', async () => {
		const declaredDays = ['08', '09', '10', '11', '12'].map((day) => ({
			date: `2024-01-${day}`,
			type: 'cp' as const,
		}));
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-09', end: '2024-01-12' },
				balances: [],
				declaredDays,
				rules: [
					{
						id: 'left',
						force: 'obligation',
						startDate: '2024-01-08',
						endDate: '2024-01-10',
						placeDays: 2,
					},
					{
						id: 'right',
						force: 'obligation',
						startDate: '2024-01-10',
						endDate: '2024-01-12',
						placeDays: 2,
					},
					{
						id: 'before',
						force: 'preference',
						startDate: '2024-01-08',
						endDate: '2024-01-08',
						placeDays: 1,
					},
					{
						id: 'after',
						force: 'preference',
						startDate: '2024-01-12',
						endDate: '2024-01-12',
						placeDays: 1,
					},
				].map((rule) => ({ ...rule, type: 'time_window', placeType: 'cp' })),
			}),
		);
		expect(result.placements).toEqual([]);
		expect(result.declaredDays).toEqual(declaredDays);
		expect(result.preferences.map(({ satisfied }) => satisfied)).toEqual([0, 0]);
		expect(
			result.timeWindowContributions?.map(({ declaredDays }) =>
				declaredDays.map(({ date }) => date),
			),
		).toEqual([
			['2024-01-09', '2024-01-10'],
			['2024-01-10', '2024-01-11'],
		]);
	});

	it('keeps an incompatible fixed RTT while placing additional CP on other dates', async () => {
		const declaredDays = [{ date: '2024-01-10', type: 'rtt' as const }];
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-08', end: '2024-01-13' },
				balances: [balance('cp', 'cp', 3, '2024-01-12')],
				declaredDays,
				rules: [
					{
						id: 'cp-only',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-08',
						endDate: '2024-01-12',
						placeDays: 3,
						placeType: 'cp',
					},
				],
			}),
		);
		expect(result.declaredDays).toEqual(declaredDays);
		expect(result.placements).toHaveLength(3);
		expect(
			result.placements.every(({ date, type }) => date !== '2024-01-10' && type === 'cp'),
		).toBe(true);
		expect(result.remainingBalances).toEqual([]);
		expect(result.timeWindowContributions).toBeUndefined();
	});

	it('preserves preference order when a partially declared higher preference needs the shared date', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-08', end: '2024-01-13' },
				balances: [
					balance('cp', 'cp', 1, '2025-01-01'),
					balance('rtt', 'rtt', 1, '2025-01-01'),
				],
				declaredDays: [{ date: '2024-01-10', type: 'cp' }],
				rules: [
					{
						id: 'higher-cp',
						startDate: '2024-01-10',
						endDate: '2024-01-11',
						placeDays: 2,
						placeType: 'cp',
					},
					{
						id: 'lower-rtt',
						startDate: '2024-01-11',
						endDate: '2024-01-11',
						placeDays: 1,
						placeType: 'rtt',
					},
				].map((rule) => ({ ...rule, type: 'time_window', force: 'preference' })),
			}),
		);
		expect(result.preferences).toMatchObject([
			{ ruleId: 'higher-cp', requested: 2, satisfied: 2 },
			{
				ruleId: 'lower-rtt',
				requested: 1,
				satisfied: 0,
				reason: { code: 'higher-priority' },
			},
		]);
		expect(result.placements).toContainEqual(
			expect.objectContaining({ date: '2024-01-11', type: 'cp', ruleIds: ['higher-cp'] }),
		);
		expect(result.declaredDays).toEqual([{ date: '2024-01-10', type: 'cp' }]);
	});

	it('keeps the joint search exhaustive when fixed credits leave a small number of new placements', async () => {
		const core = await import('./leave-planner.core');
		let artifacts: import('./leave-planner.core').PlanningArtifacts = {};
		const result = isPlan(
			core.calculatePlanningInternal(
				{
					horizon: { start: '2024-01-08', end: '2024-04-17' },
					balances: [
						balance('cp', 'cp', 1, '2025-01-01'),
						balance('rtt', 'rtt', 1, '2025-01-01'),
					],
					declaredDays: [
						{ date: '2024-01-08', type: 'cp' },
						{ date: '2024-01-09', type: 'rtt' },
					],
					rules: ['cp', 'rtt'].map((placeType) => ({
						id: placeType,
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-08',
						endDate: '2024-04-16',
						placeDays: 2,
						placeType,
					})),
				},
				undefined,
				(value) => (artifacts = value),
			),
		);
		expect(result.placements).toHaveLength(2);
		expect(result.placements.map(({ type }) => type).sort()).toEqual(['cp', 'rtt']);
		const evaluated =
			artifacts.trace?.phases.flatMap((phase) =>
				phase.decisions.flatMap((decision) => decision.candidates),
			) ?? [];
		expect(evaluated.some(({ reason }) => reason?.code === 'obligation-solution-limit')).toBe(
			false,
		);
		expect(
			result.timeWindowContributions?.map(({ declaredDays }) => declaredDays.length),
		).toEqual([1, 1]);
	});

	it('does not explain a fixed contribution as a free date when a higher typed preference occupies the rest of the window', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-08', end: '2024-01-13' },
				balances: [
					balance('cp', 'cp', 1, '2025-01-01'),
					balance('rtt', 'rtt', 1, '2025-01-01'),
				],
				declaredDays: [{ date: '2024-01-10', type: 'cp' }],
				rules: [
					{
						id: 'higher-rtt',
						startDate: '2024-01-11',
						endDate: '2024-01-11',
						placeDays: 1,
						placeType: 'rtt',
					},
					{
						id: 'lower-cp',
						startDate: '2024-01-10',
						endDate: '2024-01-11',
						placeDays: 2,
						placeType: 'cp',
					},
				].map((rule) => ({ ...rule, type: 'time_window', force: 'preference' })),
			}),
		);
		expect(result.preferences).toMatchObject([
			{ ruleId: 'higher-rtt', satisfied: 1 },
			{ ruleId: 'lower-cp', satisfied: 1, reason: { code: 'higher-priority' } },
		]);
	});

	it('explains an impossible joint obligation after compatible declarations have been credited', async () => {
		const core = await import('./leave-planner.core');
		let artifacts: import('./leave-planner.core').PlanningArtifacts = {};
		const declaredDays = [{ date: '2024-01-08', type: 'cp' as const }];
		const result = core.calculatePlanningInternal(
			{
				horizon: { start: '2024-01-08', end: '2024-01-13' },
				balances: [balance('cp', 'cp', 2), balance('rtt', 'rtt', 1)],
				declaredDays,
				labels: { 'three-cp': 'Three CP including Monday', 'one-rtt': 'Wednesday RTT' },
				rules: [
					{
						id: 'three-cp',
						startDate: '2024-01-08',
						endDate: '2024-01-10',
						placeDays: 3,
						placeType: 'cp',
					},
					{
						id: 'one-rtt',
						startDate: '2024-01-10',
						endDate: '2024-01-10',
						placeDays: 1,
						placeType: 'rtt',
					},
				].map((rule) => ({ ...rule, type: 'time_window', force: 'obligation' })),
			},
			undefined,
			(value) => (artifacts = value),
		);
		expect(result).toMatchObject({
			kind: 'PlanningConflict',
			conflictingRuleIds: ['three-cp', 'one-rtt'],
			reasons: [{ code: 'joint-date-conflict' }],
		});
		expect(artifacts.explanation).toMatchObject({
			kind: 'ConflictExplanation',
			conflictingRules: [
				{ id: 'three-cp', label: 'Three CP including Monday' },
				{ id: 'one-rtt', label: 'Wednesday RTT' },
			],
			bottleneck: { code: 'joint-date-conflict' },
		});
		expect(artifacts.trace?.initialState.declaredDays).toEqual(declaredDays);
	});

	it('distinguishes insufficient compatible leave from malformed rules without converting a fixed RTT', async () => {
		const submitted = {
			horizon: { start: '2024-01-08', end: '2024-01-13' },
			balances: [balance('cp', 'cp', 4)],
			declaredDays: [{ date: '2024-01-10', type: 'rtt' as const }],
			rules: [
				{
					id: 'cp-only',
					type: 'time_window',
					force: 'obligation',
					startDate: '2024-01-08',
					endDate: '2024-01-12',
					placeDays: 5,
					placeType: 'cp',
				},
			],
		};
		expect(await runInNonBrowser(submitted)).toMatchObject({
			kind: 'PlanningConflict',
			reasons: [{ code: 'typed-capacity' }],
		});
		submitted.rules[0].placeDays = -1;
		expect(await runInNonBrowser(submitted)).toMatchObject({ kind: 'InvalidInput' });
		expect(submitted.declaredDays).toEqual([{ date: '2024-01-10', type: 'rtt' }]);
	});

	it('keeps declared non-working days fixed without consuming their remaining balances', async () => {
		const declaredDays = [
			{ date: '2024-01-02', type: 'cp' as const },
			{ date: '2024-01-03', type: 'rtt' as const },
			{ date: '2024-01-05', type: 'other' as const },
			{ date: '2026-10-06', type: 'other' as const },
		];
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-06' },
				balances: [balance('remaining-cp', 'cp', 4, '2024-01-05')],
				rules: [],
				declaredDays,
			}),
		);
		expect(result).toMatchObject({ declaredDays });
		expect(result.placements.map(({ date }) => date)).toEqual(['2024-01-04']);
		expect(result.remainingBalances).toMatchObject([{ id: 'remaining-cp', quantity: 3 }]);
	});

	it('accepts declarations without a source balance or a new placement', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon,
				balances: [],
				rules: [],
				declaredDays: [{ date: '2024-01-02', type: 'other' }],
			}),
		);
		expect(result.declaredDays).toEqual([{ date: '2024-01-02', type: 'other' }]);
		expect(result.placements).toEqual([]);
		expect(result.remainingBalances).toEqual([]);
	});

	it('forms Friday–Sunday from an ordinary declared Other day without a balance debit', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-09' },
				balances: [],
				rules: [],
				declaredDays: [{ date: '2024-01-05', type: 'other' }],
			}),
		);
		expect(result.placements).toEqual([]);
		expect(result.remainingBalances).toEqual([]);
		expect(result.timeOffPeriods).toEqual([
			{
				start: '2024-01-05',
				end: '2024-01-07',
				duration: 3,
				placementDates: [],
				declaredDates: ['2024-01-05'],
				nonWorkingDates: ['2024-01-06', '2024-01-07'],
				nonWorkingDayGain: 2,
			},
		]);
		expect(result.metrics).toMatchObject({
			nonWorkingDayGain: 2,
			averageWorkSequence: 2,
			longestWorkSequence: 3,
			averageTimeOffPeriod: 3,
			longestTimeOffPeriod: 3,
		});
	});

	it('merges declarations, placements, weekends and national holidays without counting dates twice', async () => {
		const declaredDays = [
			{ date: '2024-05-06', type: 'cp' as const },
			{ date: '2024-05-07', type: 'rtt' as const },
			{ date: '2024-05-10', type: 'other' as const },
		];
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-05-06', end: '2024-05-14' },
				balances: [
					{ ...balance('cp', 'cp', 1, '2024-05-13'), availableFrom: '2024-05-13' },
				],
				rules: [],
				declaredDays,
			}),
		);
		expect(result.declaredDays).toEqual(declaredDays);
		expect(result.placements.map(({ date }) => date)).toEqual(['2024-05-13']);
		expect(result.remainingBalances).toEqual([]);
		expect(result.timeOffPeriods).toEqual([
			{
				start: '2024-05-04',
				end: '2024-05-13',
				duration: 10,
				placementDates: ['2024-05-13'],
				declaredDates: declaredDays.map(({ date }) => date),
				nonWorkingDates: [
					'2024-05-04',
					'2024-05-05',
					'2024-05-08',
					'2024-05-09',
					'2024-05-11',
					'2024-05-12',
				],
				nonWorkingDayGain: 6,
			},
		]);
		expect(result.metrics).toMatchObject({
			nonWorkingDayGain: 6,
			holidayWeekValue: 5,
			averageWorkSequence: null,
			longestWorkSequence: 0,
			averageTimeOffPeriod: 10,
			longestTimeOffPeriod: 10,
		});
	});

	it('uses declared days to split work sequences while weekends and holidays alone never split them', async () => {
		const withDeclarations = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-20' },
				balances: [],
				rules: [],
				declaredDays: [
					{ date: '2024-01-05', type: 'other' },
					{ date: '2024-01-09', type: 'cp' },
				],
			}),
		);
		expect(withDeclarations.metrics).toMatchObject({
			longestWorkSequence: 8,
			shortSequenceDeficit: 4,
		});
		const withoutDeclarations = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-05-06', end: '2024-05-15' },
				balances: [],
				rules: [],
			}),
		);
		expect(withoutDeclarations.timeOffPeriods).toEqual([]);
		expect(withoutDeclarations.metrics).toMatchObject({
			longestWorkSequence: 5,
			shortSequenceDeficit: 0,
			nonWorkingDayGain: 0,
		});
	});

	it('extends only anchored periods with adjacent outside declarations and keeps placements inside the submitted horizon', async () => {
		const selectedHorizon = { start: '2024-01-03', end: '2024-01-05' };
		const declaredDays = [
			{ date: '2024-01-02', type: 'cp' as const },
			{ date: '2024-01-03', type: 'other' as const },
			{ date: '2024-01-05', type: 'rtt' as const },
			{ date: '2024-01-10', type: 'other' as const },
		];
		const result = isPlan(
			await runInNonBrowser({
				horizon: selectedHorizon,
				balances: [
					{ ...balance('cp', 'cp', 2, '2024-01-04'), availableFrom: '2024-01-04' },
				],
				rules: [],
				declaredDays,
			}),
		);
		expect(result.horizon).toEqual(selectedHorizon);
		expect(result.declaredDays).toEqual(declaredDays);
		expect(result.placements.map(({ date }) => date)).toEqual(['2024-01-04']);
		expect(result.remainingBalances[0].quantity).toBe(1);
		expect(result.timeOffPeriods).toHaveLength(1);
		expect(result.timeOffPeriods[0]).toMatchObject({
			start: '2023-12-30',
			end: '2024-01-07',
			duration: 9,
			placementDates: ['2024-01-04'],
			declaredDates: ['2024-01-02', '2024-01-03', '2024-01-05'],
			nonWorkingDayGain: 5,
		});
		expect(result.metrics).toMatchObject({
			nonWorkingDayGain: 5,
			averageWorkSequence: null,
			longestWorkSequence: 0,
			averageTimeOffPeriod: 9,
			longestTimeOffPeriod: 9,
		});
		const unanchored = isPlan(
			await runInNonBrowser({
				horizon: selectedHorizon,
				balances: [],
				rules: [],
				declaredDays: declaredDays.filter(({ date }) => date !== '2024-01-03'),
			}),
		);
		expect(unanchored.timeOffPeriods).toEqual([]);
		expect(unanchored.metrics).toMatchObject({
			nonWorkingDayGain: 0,
			averageWorkSequence: 2,
			longestWorkSequence: 2,
			averageTimeOffPeriod: null,
			longestTimeOffPeriod: null,
		});
	});

	it.each([
		['2021-05-14', '2021-05-15', '2021-05-14', '2021-05-13', '2021-05-16'],
		['2024-01-01', '2027-01-01', '2026-12-24', '2026-12-24', '2026-12-27'],
	])(
		'keeps explicit historical and multi-year bounds from %s to %s around declarations',
		async (start, end, date, periodStart, periodEnd) => {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start, end },
					balances: [],
					rules: [],
					declaredDays: [{ date, type: 'other' }],
				}),
			);
			expect(result.horizon).toEqual({ start, end });
			expect(result.placements).toEqual([]);
			expect(result.timeOffPeriods).toHaveLength(1);
			expect(result.timeOffPeriods[0]).toMatchObject({
				start: periodStart,
				end: periodEnd,
				declaredDates: [date],
			});
		},
	);

	it.each([
		[false, '2024-05-06', '2024-05-13'],
		[true, '2024-05-06', '2024-05-13'],
		[false, '2024-05-06', '2024-05-10'],
		[false, '2024-05-06', '2024-05-09'],
		[false, '2024-05-10', '2024-05-11'],
		[true, '2024-05-10', '2024-05-11'],
	] as const)(
		'completes a genuine public-holiday week with fixed declarations and additional placement: %s',
		async (mixed, start, end) => {
			const declaredDays = ['2024-05-06', '2024-05-07', ...(mixed ? [] : ['2024-05-10'])].map(
				(date) => ({ date, type: 'other' as const }),
			);
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start, end },
					rules: [],
					declaredDays,
					balances: mixed
						? [{ ...balance('cp', 'cp', 1, '2024-05-10'), availableFrom: '2024-05-10' }]
						: [],
				}),
			);
			expect(result.metrics.holidayWeekValue).toBe(5);
			expect(result.placements.map(({ date }) => date)).toEqual(mixed ? ['2024-05-10'] : []);
			expect(result.timeOffPeriods[0].nonWorkingDates).not.toContain('2024-05-06');
		},
	);

	it('does not treat a fully declared ordinary week as a national public-holiday week', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-08', end: '2024-01-13' },
				balances: [],
				rules: [],
				declaredDays: [
					'2024-01-08',
					'2024-01-09',
					'2024-01-10',
					'2024-01-11',
					'2024-01-12',
				].map((date) => ({ date, type: 'other' })),
			}),
		);
		expect(result.metrics).toMatchObject({
			holidayWeekValue: 0,
			nonWorkingDayGain: 4,
			longestWorkSequence: 0,
		});
	});

	it.each([
		{
			declaredStart: '2024-01-02',
			declaredEnd: '2025-04-30',
			horizon: { start: '2024-01-02', end: '2024-01-03' },
			period: { start: '2023-12-30', end: '2025-04-29' },
		},
		{
			declaredStart: '2024-12-30',
			declaredEnd: '2026-01-06',
			horizon: { start: '2024-12-30', end: '2024-12-31' },
			period: { start: '2024-12-28', end: '2026-01-05' },
		},
		{
			declaredStart: '2023-11-29',
			declaredEnd: '2025-01-03',
			horizon: { start: '2025-01-02', end: '2025-01-03' },
			period: { start: '2023-11-29', end: '2025-01-02' },
		},
	])(
		'keeps a contiguous outside declaration chain $declaredStart–$declaredEnd across the prepared calendar buffer',
		async ({ declaredStart, declaredEnd, horizon, period }) => {
			const { isWorkingPlanningDate } = await import('./declared-non-working-days');
			const { addPlanningDays } = await import('./planning-date');
			const declaredDays: NonNullable<PlanningRequest['declaredDays']>[number][] = [];
			for (let date = declaredStart; date < declaredEnd; date = addPlanningDays(date, 1))
				if (isWorkingPlanningDate(date)) declaredDays.push({ date, type: 'other' });
			const result = isPlan(
				await runInNonBrowser({ horizon, balances: [], rules: [], declaredDays }),
			);
			expect(result.timeOffPeriods).toHaveLength(1);
			expect(result.timeOffPeriods[0]).toMatchObject({
				...period,
				declaredDates: declaredDays.map(({ date }) => date),
			});
			expect(result.timeOffPeriods[0].duration).toBe(
				result.timeOffPeriods[0].nonWorkingDates.length + declaredDays.length,
			);
			expect(result.placements).toEqual([]);
		},
	);

	it('preserves holiday-week priority over a larger natural-day gain around declarations', async () => {
		const request: PlanningRequest = {
			horizon: { start: '2026-11-01', end: '2026-12-01' },
			balances: [balance('cp', 'cp', 2, '2026-11-30')],
			rules: [],
			declaredDays: [
				{ date: '2026-11-09', type: 'other' },
				{ date: '2026-11-10', type: 'rtt' },
			],
		};
		const result = isPlan(await runInNonBrowser(request));
		expect(result.placements.map(({ date }) => date)).toEqual(['2026-11-12', '2026-11-13']);
		expect(result.metrics).toMatchObject({
			unplacedAtRisk: 0,
			holidayWeekValue: 3,
			nonWorkingDayGain: 5,
		});
		const withPreference = isPlan(
			await runInNonBrowser({
				...request,
				rules: [
					{
						id: 'preferred-friday',
						type: 'time_window',
						force: 'preference',
						startDate: '2026-11-20',
						endDate: '2026-11-20',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			}),
		);
		expect(withPreference.preferences[0].satisfied).toBe(1);
		expect(withPreference.metrics).toMatchObject({ unplacedAtRisk: 0, holidayWeekValue: 0 });
		const supporting = isPlan(
			await runInNonBrowser({ ...request, balances: [balance('cp', 'cp', 2, '2027-01-01')] }),
		);
		expect(supporting.placements.map(({ date }) => date)).toEqual(['2026-11-12', '2026-11-13']);
		expect(supporting.placements.every(({ supporting }) => supporting)).toBe(true);
		expect(supporting.metrics).toMatchObject({ holidayWeekValue: 3, supportingPlacements: 2 });
	});

	it.each([
		null,
		{},
		[null],
		[{ date: '2024-02-30', type: 'cp' }],
		[{ date: '2024-01-06', type: 'cp' }],
		[{ date: '2024-05-08', type: 'cp' }],
		[{ date: '2024-01-02', type: 'any' }],
		[
			{ date: '2024-01-02', type: 'cp' },
			{ date: '2024-01-02', type: 'rtt' },
		],
	])('reports malformed declarations as invalid planning input: %j', async (declaredDays) => {
		const outcome = await runInNonBrowser({
			horizon,
			balances: [],
			rules: [],
			declaredDays,
		} as unknown as PlanningRequest);
		expect(outcome).toMatchObject({
			kind: 'InvalidInput',
			reasons: [{ code: 'declared-days' }],
		});
	});

	it.each([
		['one leap day', '2024-02-29', '2024-03-01', '2024-02-29', '2024-02-29', '2024-02-29'],
		['historical day', '2021-05-14', '2021-05-15', '2021-05-14', '2021-05-13', '2021-05-16'],
		['two years', '2024-01-01', '2026-01-01', '2025-12-24', '2025-12-24', '2025-12-25'],
		['three years', '2024-01-01', '2027-01-01', '2026-12-24', '2026-12-24', '2026-12-27'],
	])(
		'plans a light %s horizon with dated provenance and French holidays',
		async (_, start, end, placementDate, periodStart, periodEnd) => {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start, end },
					balances: [
						{
							id: 'expired',
							type: 'rtt',
							quantity: 2,
							availableFrom: '2020-01-01',
							expiryDate: '2020-12-31',
						},
						{
							id: 'dated-cp',
							type: 'cp',
							quantity: 1,
							availableFrom: placementDate,
							expiryDate: placementDate,
						},
					],
					rules: [
						{
							id: 'chosen-date',
							type: 'time_window',
							force: 'obligation',
							startDate: placementDate,
							endDate: placementDate,
							placeDays: 1,
							placeType: 'cp',
						},
					],
				}),
			);
			expect(result.horizon).toEqual({ start, end });
			expect(result.placements).toEqual([
				{
					date: placementDate,
					balanceId: 'dated-cp',
					type: 'cp',
					ruleIds: ['chosen-date'],
					supporting: false,
				},
			]);
			expect(result.timeOffPeriods).toHaveLength(1);
			expect(result.timeOffPeriods[0]).toMatchObject({ start: periodStart, end: periodEnd });
			expect(result.remainingBalances.find((item) => item.id === 'expired')).toMatchObject({
				quantity: 2,
				type: 'rtt',
				availableFrom: '2020-01-01',
				expiryDate: '2020-12-31',
				classification: 'unavoidable-expiry',
			});
		},
	);

	it('rejects malformed horizons before calculation', async () => {
		const result = await planLeave({
			horizon: { start: '2025-01-01', end: '2024-01-01' },
			balances: [],
			rules: [],
		});

		expect(result.kind).toBe('InvalidInput');
		if (result.kind === 'InvalidInput') expect(result.reasons[0].code).toBe('horizon-order');
	});

	it.each([
		['2024-02-30', '2025-01-01', 'horizon-start'],
		['2024-13-01', '2025-01-01', 'horizon-start'],
		['2024-01-01', '2024-00-01', 'horizon-end'],
		['not-a-date', '2025-01-01', 'horizon-start'],
	])('reports an invalid horizon date without throwing: %s to %s', async (start, end, code) => {
		const outcome = await planLeave({ horizon: { start, end }, balances: [], rules: [] });
		expect(outcome.kind).toBe('InvalidInput');
		if (outcome.kind === 'InvalidInput')
			expect(outcome.reasons.map((item) => item.code)).toContain(code);
	});

	it.each([
		[
			'invalid balance quantity',
			{
				balances: [{ id: 'cp', type: 'cp', quantity: -1, expiryDate: '2025-01-01' }],
				rules: [],
			},
			'balance-quantity',
		],
		[
			'invalid balance expiry',
			{
				balances: [{ id: 'cp', type: 'cp', quantity: 1, expiryDate: 'not-a-date' }],
				rules: [],
			},
			'balance-expiry',
		],
		[
			'invalid rule selector',
			{
				balances: [],
				rules: [
					{
						id: 'rule',
						type: 'time_window',
						startDate: '2024-01-01',
						endDate: '2024-01-02',
						placeDays: 1,
						placeType: 'holiday',
					},
				],
			},
			'rule-selector',
		],
	] as const)('returns a table-driven validation reason for %s', async (_, request, code) => {
		const result = await runInNonBrowser({ horizon, ...request });
		expect(result.kind).toBe('InvalidInput');
		if (result.kind === 'InvalidInput')
			expect(result.reasons.some((candidate) => candidate.code === code)).toBe(true);
	});

	it('plans dated balances without mutating the request and classifies the remainder', async () => {
		const request = {
			horizon,
			balances: [
				{ ...balance('expired', 'cp', 1, '2023-12-31'), availableFrom: '2023-01-01' },
				balance('future', 'rtt', 1, '2026-01-01'),
			],
			rules: [],
		};
		const before = JSON.stringify(request);
		const result = isPlan(await runInNonBrowser(request));

		expect(JSON.stringify(request)).toBe(before);
		expect(result.placements.length).toBeLessThanOrEqual(1);
		expect(result.remainingBalances[0].classification).toBe('unavoidable-expiry');
	});

	it('migrates a legacy balance without availability to the horizon start', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-06-01', end: '2024-06-02' },
				balances: [{ id: 'legacy', type: 'cp', quantity: 1, expiryDate: '2025-01-01' }],
				rules: [],
			}),
		);
		expect(result.remainingBalances[0].availableFrom).toBe('2024-06-01');
	});

	it.each([
		['unavoidable-expiry', '2024-05-31', '2024-01-01', 'unavoidable-expiry'],
		['at-risk', '2024-06-10', '2024-06-10', 'available-after-horizon'],
		['deferred', '2024-07-01', '2024-06-11', 'available-after-horizon'],
	] as const)(
		'classifies a remaining balance as %s',
		async (classification, expiryDate, availableFrom, reasonCode) => {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2024-06-01', end: '2024-06-10' },
					balances: [
						{
							id: classification,
							type: 'cp',
							quantity: 1,
							availableFrom,
							expiryDate,
						},
					],
					rules: [],
				}),
			);
			expect(result.remainingBalances[0].classification).toBe(classification);
			expect(result.remainingBalances[0].reason.code).toBe(reasonCode);
		},
	);

	it.each([
		['no-working-date', '2024-06-08', '2024-06-10', []],
		['all-dates-occupied', '2024-06-03', '2024-06-04', [{ date: '2024-06-03', type: 'cp' }]],
		['preserved', '2024-06-04', '2024-06-13', [{ date: '2024-06-07', type: 'cp' }]],
	] as const)(
		'explains a remaining deferred balance as %s without treating it as unavailable',
		async (code, start, end, declaredDays) => {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start, end },
					balances: [
						{ ...balance('other', 'other', 1, '2025-05-10'), availableFrom: start },
					],
					declaredDays,
					rules: [],
				}),
			);
			expect(result.placements).toEqual([]);
			expect(result.remainingBalances).toMatchObject([
				{
					id: 'other',
					quantity: 1,
					classification: 'deferred',
					reason: { code },
				},
			]);
		},
	);

	it('satisfies exact TIME_WINDOW obligations and reports typed conflicts', async () => {
		const rule = {
			id: 'cp-window',
			type: 'time_window',
			force: 'obligation',
			startDate: '2024-03-01',
			endDate: '2024-03-05',
			placeDays: 2,
			placeType: 'cp',
		};
		const plan = isPlan(
			await runInNonBrowser({ horizon, balances: [balance('cp', 'cp', 2)], rules: [rule] }),
		);
		expect(plan.placements).toHaveLength(2);
		expect(plan.placements.every((placement) => placement.ruleIds).valueOf()).toBe(true);

		const conflict = await runInNonBrowser({
			horizon,
			balances: [balance('rtt', 'rtt', 2)],
			rules: [rule],
		});
		expect(conflict.kind).toBe('PlanningConflict');
	});

	it('lets one ANY obligation preserve a typed balance for another obligation', async () => {
		const rules = [
			{
				id: 'any',
				type: 'time_window',
				force: 'obligation',
				startDate: '2024-04-01',
				endDate: '2024-04-02',
				placeDays: 1,
				placeType: 'any',
			},
			{
				id: 'cp',
				type: 'time_window',
				force: 'obligation',
				startDate: '2024-04-01',
				endDate: '2024-02-02',
				placeDays: 1,
				placeType: 'cp',
			},
		];
		// The second window is intentionally corrected below to keep this table readable.
		rules[1].endDate = '2024-04-02';
		const plan = isPlan(
			await runInNonBrowser({
				horizon,
				balances: [balance('cp', 'cp', 1), balance('rtt', 'rtt', 1)],
				rules,
			}),
		);

		expect(plan.placements).toHaveLength(2);
		expect(plan.placements.find((placement) => placement.ruleIds.includes('cp'))?.type).toBe(
			'cp',
		);
		expect(
			plan.placements.some(
				(placement) =>
					placement.ruleIds.includes('any') && placement.ruleIds.includes('cp'),
			),
		).toBe(true);
	});

	it('supports IF_THEN patterns, merged periods, and deterministic results', async () => {
		const rule = {
			id: 'holiday',
			type: 'if_then',
			force: 'obligation',
			dayOfWeek: 3,
			placeDays: 2,
			placeType: 'cp',
			placement: 'auto',
			rewardDays: 1,
			rewardType: 'rtt',
		};
		const request = {
			horizon: { start: '2024-04-01', end: '2024-05-10' },
			balances: [balance('cp', 'cp', 4), balance('rtt', 'rtt', 1, '2026-01-01')],
			rules: [rule],
		};
		const first = isPlan(await runInNonBrowser(request));
		const second = isPlan(await runInNonBrowser(request));
		expect(first).toEqual(second);
		expect(first.placements.length).toBeGreaterThanOrEqual(4);
		expect(first.timeOffPeriods[0].duration).toBeGreaterThan(2);
	});

	it('selects a joint obligation assignment by later preference quality', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-02-01', end: '2024-02-10' },
				balances: [balance('cp', 'cp', 1)],
				rules: [
					{
						id: 'obligation',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-02-01',
						endDate: '2024-02-05',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'preference',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-02-05',
						endDate: '2024-02-05',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			}),
		);
		expect(
			result.placements.find((placement) => placement.ruleIds.includes('obligation'))?.date,
		).toBe('2024-02-05');
		expect(result.preferences[0].satisfied).toBe(1);
	});

	it('preserves an at-risk balance while satisfying a deferred obligation', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-04' },
				balances: [
					{
						...balance('cp', 'cp', 1, '2024-01-02'),
						availableFrom: '2024-01-02',
					},
					{
						...balance('rtt', 'rtt', 1, '2025-01-01'),
						availableFrom: '2024-01-02',
					},
				],
				rules: [
					{
						id: 'rtt-obligation',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-02',
						endDate: '2024-01-03',
						placeDays: 1,
						placeType: 'rtt',
					},
				],
			}),
		);
		expect(
			result.placements.find((placement) => placement.ruleIds.includes('rtt-obligation'))
				?.date,
		).toBe('2024-01-03');
		expect(result.placements.find((placement) => placement.balanceId === 'cp')?.date).toBe(
			'2024-01-02',
		);
	});

	it('does not let a generating period reward finance an earlier merged period placement', async () => {
		const result = await runInNonBrowser({
			horizon: { start: '2024-04-25', end: '2024-05-15' },
			balances: [balance('cp', 'cp', 2), balance('rtt', 'rtt', 3, '2026-01-01')],
			rules: [
				{
					id: 'producer',
					type: 'if_then',
					force: 'obligation',
					dayOfWeek: 3,
					placeDays: 1,
					placeType: 'cp',
					placement: 'before',
					rewardDays: 1,
					rewardType: 'rtt',
				},
				{
					id: 'consumer',
					type: 'if_then',
					force: 'obligation',
					dayOfWeek: 4,
					placeDays: 4,
					placeType: 'rtt',
					placement: 'before',
					rewardDays: 0,
				},
			],
		});
		expect(result.kind).toBe('PlanningConflict');
	});

	it('chains an earned balance into a later obligation with provenance', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-04-25', end: '2024-05-08' },
				balances: [balance('cp', 'cp', 1), balance('rtt', 'rtt', 0, '2026-01-01')],
				rules: [
					{
						id: 'producer',
						type: 'if_then',
						force: 'obligation',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'after',
						rewardDays: 1,
						rewardType: 'rtt',
					},
					{
						id: 'consumer',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-07',
						endDate: '2024-05-07',
						placeDays: 1,
						placeType: 'rtt',
					},
				],
			}),
		);
		const earned = result.placements.find((placement) =>
			placement.ruleIds.includes('consumer'),
		);
		expect(earned?.balanceId).toBe('earned:producer:2024-05-01');
		expect(earned?.ruleIds).toEqual(['consumer']);
	});

	it('allows a later preference producer to fund an earlier consumer chronologically', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-04-25', end: '2024-05-08' },
				balances: [balance('cp', 'cp', 1), balance('rtt', 'rtt', 0, '2026-01-01')],
				rules: [
					{
						id: 'consumer',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-05-07',
						endDate: '2024-05-07',
						placeDays: 1,
						placeType: 'rtt',
					},
					{
						id: 'producer',
						type: 'if_then',
						force: 'preference',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'after',
						rewardDays: 1,
						rewardType: 'rtt',
					},
				],
			}),
		);
		expect(result.preferences.map((preference) => preference.satisfied)).toEqual([1, 1]);
		expect(result.placements).toEqual(
			expect.arrayContaining([
				expect.objectContaining({
					date: '2024-05-02',
					balanceId: 'cp',
					ruleIds: ['producer'],
				}),
				expect.objectContaining({
					date: '2024-05-07',
					balanceId: 'earned:producer:2024-05-01',
					ruleIds: ['consumer'],
				}),
			]),
		);
	});

	it('preserves preference priority when one later producer earns only one day', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-04-25', end: '2024-05-08' },
				balances: [balance('cp', 'cp', 1), balance('rtt', 'rtt', 0, '2026-01-01')],
				rules: [
					{
						id: 'first',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-05-06',
						endDate: '2024-05-06',
						placeDays: 1,
						placeType: 'rtt',
					},
					{
						id: 'second',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-05-07',
						endDate: '2024-05-07',
						placeDays: 1,
						placeType: 'rtt',
					},
					{
						id: 'producer',
						type: 'if_then',
						force: 'preference',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'after',
						rewardDays: 1,
						rewardType: 'rtt',
					},
				],
			}),
		);
		expect(result.preferences.map((preference) => preference.satisfied)).toEqual([1, 0, 1]);
		expect(result.placements).toEqual(
			expect.arrayContaining([
				expect.objectContaining({ date: '2024-05-06', ruleIds: ['first'] }),
			]),
		);
	});

	it('replays the current preference when an earlier retry creates its entitlement', async () => {
		vi.setSystemTime(new Date('2021-01-01T12:00:00Z'));
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2021-05-20', end: '2021-11-03' },
				balances: [
					{
						id: 'cp',
						type: 'cp',
						quantity: 0,
						availableFrom: '2021-05-20',
						expiryDate: '2022-01-01',
					},
					{
						id: 'rtt',
						type: 'rtt',
						quantity: 1,
						availableFrom: '2021-05-20',
						expiryDate: '2021-08-01',
					},
				],
				rules: [
					{
						id: 'wednesday-producer',
						type: 'if_then',
						force: 'preference',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'after',
						rewardDays: 1,
						rewardType: 'rtt',
					},
					{
						id: 'monday-chain',
						type: 'if_then',
						force: 'preference',
						dayOfWeek: 1,
						placeDays: 1,
						placeType: 'rtt',
						placement: 'after',
						rewardDays: 1,
						rewardType: 'cp',
					},
				],
			}),
		);
		expect(result.preferences.map((preference) => preference.satisfied)).toEqual([1, 2]);
		expect(result.placements).toEqual(
			expect.arrayContaining([
				expect.objectContaining({ date: '2021-07-15', ruleIds: ['wednesday-producer'] }),
				expect.objectContaining({ date: '2021-11-02', ruleIds: ['monday-chain'] }),
			]),
		);
	});

	it('retains a useful supporting placement while preserving its provenance', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-05', end: '2024-01-10' },
				balances: [balance('cp', 'cp', 1, '2025-01-01')],
				rules: [],
			}),
		);
		const supporting = result.placements.find((placement) => placement.supporting);
		expect(supporting?.ruleIds).toEqual([]);
		expect(supporting?.balanceId).toBe('cp');
	});

	it('does not trade a short-sequence deficit for supporting placement gain', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-01', end: '2024-02-01' },
				balances: [balance('cp-four', 'cp', 4, '2025-01-01')],
				rules: [],
			}),
		);
		expect(result.metrics.shortSequenceDeficit).toBe(0);
	});

	it('retains supporting provenance when a placement is moved', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-01', end: '2024-01-29' },
				balances: [balance('cp-six', 'cp', 6, '2025-01-01')],
				rules: [],
			}),
		);
		expect(result.metrics.supportingPlacements).toBe(
			result.placements.filter((placement) => placement.supporting).length,
		);
		expect(result.placements.length).toBeGreaterThan(0);
		expect(result.placements.every((placement) => placement.supporting)).toBe(true);
	});

	it('orders non-working gain, longest sequence, and final dates lexicographically', async () => {
		const twoDayPlan = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-02-01', end: '2024-03-01' },
				balances: [balance('cp', 'cp', 2, '2024-02-29')],
				rules: [],
			}),
		);
		const fourDayPlan = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-02-01', end: '2024-03-01' },
				balances: [balance('cp', 'cp', 4, '2024-02-29')],
				rules: [],
			}),
		);
		expect(twoDayPlan.placements.map((placement) => placement.date)).toEqual([
			'2024-02-09',
			'2024-02-19',
		]);
		expect(fourDayPlan.placements.map((placement) => placement.date)).toEqual([
			'2024-02-02',
			'2024-02-09',
			'2024-02-16',
			'2024-02-23',
		]);
	});

	it.each([
		[
			'11 November',
			{ start: '2026-11-01', end: '2026-12-01' },
			'2026-11-30',
			['2026-11-09', '2026-11-10', '2026-11-12', '2026-11-13'],
		],
		[
			'14 July',
			{ start: '2027-07-01', end: '2027-08-01' },
			'2027-07-31',
			['2027-07-12', '2027-07-13', '2027-07-15', '2027-07-16'],
		],
	] as const)('takes the full week around %s', async (_, holidayHorizon, expiryDate, dates) => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: holidayHorizon,
				balances: [balance('cp', 'cp', 4, expiryDate)],
				rules: [],
			}),
		);

		expect(result.placements.map((placement) => placement.date)).toEqual(dates);
		expect(result.timeOffPeriods).toHaveLength(1);
		expect(result.timeOffPeriods[0].duration).toBe(9);
	});

	// Async calculation yields to the test timer; allow the planner's ten-second budget.
	it('uses the 11 November and 14 July weeks in the representative default plan', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2026-08-29', end: '2027-08-29' },
				balances: [
					{
						...balance('cp', 'cp', 10, '2027-08-29'),
						availableFrom: '2026-08-29',
					},
					{
						...balance('rtt', 'rtt', 10, '2027-08-29'),
						availableFrom: '2026-08-29',
					},
					{
						...balance('other', 'other', 4, '2027-08-29'),
						availableFrom: '2026-08-29',
					},
				],
				rules: [
					{
						id: 'default-samedi-malin',
						name: 'Samedi Malin',
						type: 'if_then',
						force: 'preference',
						dayOfWeek: 6,
						placeDays: 2,
						placeType: 'cp',
						placement: 'auto',
						rewardDays: 1,
						rewardType: 'other',
					},
					{
						id: 'default-christmas',
						name: 'Christmas holidays',
						type: 'time_window',
						force: 'preference',
						startDate: '2026-12-20',
						endDate: '2027-01-03',
						placeDays: 5,
						placeType: 'any',
					},
				],
			}),
		);

		expect(result.placements.map((placement) => placement.date)).toEqual(
			expect.arrayContaining([
				'2026-11-09',
				'2026-11-10',
				'2026-11-12',
				'2026-11-13',
				'2027-07-12',
				'2027-07-13',
				'2027-07-15',
				'2027-07-16',
			]),
		);
	}, 15_000);

	it('moves a satisfied time-window preference to complete a holiday week', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2027-07-01', end: '2027-08-01' },
				balances: [balance('cp', 'cp', 4, '2027-07-31')],
				rules: [
					{
						id: 'july',
						type: 'time_window',
						force: 'preference',
						startDate: '2027-07-01',
						endDate: '2027-07-31',
						placeDays: 4,
						placeType: 'any',
					},
				],
			}),
		);

		expect(result.preferences[0].satisfied).toBe(4);
		expect(result.placements.map((placement) => placement.date)).toEqual([
			'2027-07-12',
			'2027-07-13',
			'2027-07-15',
			'2027-07-16',
		]);
	});

	it('uses deferred leave as supporting placements to complete a holiday week', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2027-07-01', end: '2027-08-01' },
				balances: [balance('cp', 'cp', 4, '2028-07-31')],
				rules: [],
			}),
		);

		expect(result.placements.map((placement) => placement.date)).toEqual([
			'2027-07-12',
			'2027-07-13',
			'2027-07-15',
			'2027-07-16',
		]);
		expect(result.placements.every((placement) => placement.supporting)).toBe(true);
	});

	it('moves a time-window obligation to improve a later quality stage', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-08', end: '2024-01-15' },
				balances: [balance('cp', 'cp', 1)],
				rules: [
					{
						id: 'window',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-09',
						endDate: '2024-01-12',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			}),
		);
		expect(result.placements[0].date).toBe('2024-01-12');
	});

	it('shares future ANY preference demand and preserves preference order', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-02-01', end: '2024-02-12' },
				balances: [balance('cp', 'cp', 1)],
				rules: [
					{
						id: 'first',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-02-05',
						endDate: '2024-02-08',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'any',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-02-07',
						endDate: '2024-02-09',
						placeDays: 1,
						placeType: 'any',
					},
				],
			}),
		);
		expect(result.placements[0].date).toBe('2024-02-07');
		expect(result.preferences.map((preference) => preference.satisfied)).toEqual([1, 1]);
	});

	it.each(['cp', 'any'] as const)(
		'shares an existing compatible placement before consuming a day for a %s preference',
		async (lastSelector) => {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2024-01-02', end: '2024-01-15' },
					balances: [balance('cp', 'cp', 3)],
					rules: [
						{
							id: 'high',
							type: 'time_window',
							force: 'preference',
							startDate: '2024-01-05',
							endDate: '2024-01-08',
							placeDays: 2,
							placeType: 'cp',
						},
						{
							id: 'middle',
							type: 'time_window',
							force: 'preference',
							startDate: '2024-01-03',
							endDate: '2024-01-10',
							placeDays: 1,
							placeType: 'cp',
						},
						{
							id: 'low',
							type: 'time_window',
							force: 'preference',
							startDate: '2024-01-12',
							endDate: '2024-01-12',
							placeDays: 1,
							placeType: lastSelector,
						},
					],
				}),
			);
			expect(result.preferences.map((preference) => preference.satisfied)).toEqual([2, 1, 1]);
		},
	);

	it('uses the earliest unsatisfied preference slot as a cardinality look-ahead', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-08' },
				balances: [balance('cp', 'cp', 1)],
				rules: [
					{
						id: 'flexible',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-01-02',
						endDate: '2024-01-05',
						placeDays: 1,
						placeType: 'any',
					},
					{
						id: 'second',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-01-05',
						endDate: '2024-01-05',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'third',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-01-02',
						endDate: '2024-01-02',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			}),
		);
		expect(result.placements[0].date).toBe('2024-01-05');
		expect(result.preferences.map((preference) => preference.satisfied)).toEqual([1, 1, 0]);
	});

	it('classifies a later preference blocked by consumed higher-priority capacity', async () => {
		const result = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-02', end: '2024-01-08' },
				balances: [balance('cp', 'cp', 1, '2025-01-01')],
				rules: [
					{
						id: 'high',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-01-02',
						endDate: '2024-01-02',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'low',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-01-05',
						endDate: '2024-01-05',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			}),
		);
		expect(result.preferences[0].satisfied).toBe(1);
		expect(result.preferences[1].reason?.code).toBe('higher-priority');
	});

	it('keeps holiday occurrences date-only across host timezones', async () => {
		const previousTimezone = process.env['TZ'];
		process.env['TZ'] = 'Asia/Tokyo';
		try {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2023-12-29', end: '2024-01-05' },
					balances: [balance('cp', 'cp', 1)],
					rules: [
						{
							id: 'new-year',
							type: 'if_then',
							force: 'obligation',
							dayOfWeek: 1,
							placeDays: 1,
							placeType: 'cp',
							placement: 'after',
							rewardDays: 0,
						},
					],
				}),
			);
			expect(result.placements[0].date).toBe('2024-01-02');
		} finally {
			if (previousTimezone === undefined) delete process.env['TZ'];
			else process.env['TZ'] = previousTimezone;
		}
	});

	it('rejects around N=1 while supporting valid around splits', async () => {
		const aroundOne = await runInNonBrowser({
			horizon: { start: '2024-04-25', end: '2024-05-15' },
			balances: [balance('cp-one', 'cp', 2)],
			rules: [
				{
					id: 'around-one',
					type: 'if_then',
					force: 'obligation',
					dayOfWeek: 3,
					placeDays: 1,
					placeType: 'cp',
					placement: 'around',
					rewardDays: 0,
				},
			],
		});
		expect(aroundOne.kind).toBe('PlanningConflict');

		const aroundPreference = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-04-25', end: '2024-05-15' },
				balances: [balance('cp-pref', 'cp', 1)],
				rules: [
					{
						id: 'around-preference',
						type: 'if_then',
						force: 'preference',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'around',
						rewardDays: 0,
					},
				],
			}),
		);
		expect(aroundPreference.preferences[0].satisfied).toBe(0);

		const aroundTwo = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-04-29', end: '2024-05-04' },
				balances: [balance('cp-two', 'cp', 2)],
				rules: [
					{
						id: 'around-two',
						type: 'if_then',
						force: 'obligation',
						dayOfWeek: 3,
						placeDays: 2,
						placeType: 'cp',
						placement: 'around',
						rewardDays: 0,
					},
				],
			}),
		);
		expect(aroundTwo.placements).toHaveLength(2);

		for (const mode of ['before', 'after', 'auto'] as const) {
			const result = isPlan(
				await runInNonBrowser({
					horizon: { start: '2024-04-25', end: '2024-05-15' },
					balances: [balance(`cp-${mode}`, 'cp', 2)],
					rules: [
						{
							id: `rule-${mode}`,
							type: 'if_then',
							force: 'obligation',
							dayOfWeek: 3,
							placeDays: 1,
							placeType: 'cp',
							placement: mode,
							rewardDays: 0,
						},
					],
				}),
			);
			expect(result.placements).toHaveLength(2);
			expect(
				result.placements.every((placement) => placement.ruleIds.includes(`rule-${mode}`)),
			).toBe(true);
		}
	});

	it.each([
		['2026-01-01', undefined],
		['2027-01-01', undefined],
		['2027-01-01', 25_000],
	] as const)(
		'completes every objective on a horizon ending %s after more than ten seconds (budget %s)',
		async (end, deadlineMs) => {
			const request: PlanningRequest = {
				deadlineMs,
				horizon: { start: '2024-01-01', end },
				balances: [
					{
						id: 'cp',
						type: 'cp',
						quantity: 3,
						availableFrom: '2024-05-06',
						expiryDate: '2024-05-10',
					},
				],
				rules: [
					{
						id: 'fixed',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-06',
						endDate: '2024-05-06',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			};
			const expected = isPlan(await runInNonBrowser(request));
			let elapsed = 0;
			const clock = vi.spyOn(performance, 'now').mockImplementation(() => elapsed);
			try {
				const outcome = await runInNonBrowser({
					...request,
					progress: (stage) => {
						if (stage === 'at-risk') queueMicrotask(() => (elapsed = 20_000));
					},
				});
				expect(elapsed).toBeGreaterThan(10_000);
				expect(outcome).toEqual(expected);
				expect(expected.lastCompletedStage).toBe('dates');
				expect(expected.placements).toContainEqual({
					date: '2024-05-06',
					balanceId: 'cp',
					type: 'cp',
					ruleIds: ['fixed'],
					supporting: false,
				});
			} finally {
				clock.mockRestore();
			}
		},
	);

	it('returns an incomplete outcome instead of a false conflict at an expired deadline', async () => {
		const result = await planLeave({
			horizon,
			balances: [balance('cp', 'cp', 5)],
			rules: [],
			deadlineMs: 0,
		});
		expect(result.kind).toBe('PlanningIncomplete');
	});

	it('reports worker-unavailable in a browser instead of running the core synchronously', async () => {
		const result = await planLeave({ horizon, balances: [], rules: [] });
		expect(result.kind).toBe('PlanningIncomplete');
		if (result.kind === 'PlanningIncomplete') {
			expect(result.reasons[0].code).toBe('worker-unavailable');
			expect(result.incumbent).toBeUndefined();
			expect(result.lastCompletedStage).toBeUndefined();
			expect(result.completedStages).toEqual([]);
		}
	});

	it('keeps an expired browser request off the UI thread when a worker exists', async () => {
		let started = false;
		let terminated = false;
		class ZeroBudgetWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			constructor() {
				started = true;
			}

			postMessage(): void {}

			terminate(): void {
				terminated = true;
			}
		}
		vi.stubGlobal('Worker', ZeroBudgetWorker);
		vi.useFakeTimers();
		try {
			const resultPromise = planLeave({ horizon, balances: [], rules: [], deadlineMs: 0 });
			await vi.advanceTimersByTimeAsync(30_000);
			const result = await resultPromise;
			expect(result.kind).toBe('PlanningIncomplete');
			expect(started).toBe(true);
			expect(terminated).toBe(true);
		} finally {
			vi.useRealTimers();
			vi.unstubAllGlobals();
		}
	});
});

describe('planLeave transport', () => {
	it('keeps a responsive phase active beyond repeated liveness windows and delivers its trace later', async () => {
		const request = { horizon, balances: [], rules: [] };
		const expected = isPlan(await runInNonBrowser(request));
		const workers: ResponsiveWorker[] = [];
		class ResponsiveWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;
			postMessage = vi.fn();
			terminate = vi.fn();
			constructor() {
				workers.push(this);
			}
			emit(data: unknown) {
				this.onmessage?.({ data } as MessageEvent);
			}
		}
		vi.stubGlobal('Worker', ResponsiveWorker);
		vi.useFakeTimers();
		try {
			const calculation = createPlanningCalculation(request);
			const worker = workers[0];
			let outcomeReady = false;
			let traceReady = false;
			void calculation.outcome.then(() => (outcomeReady = true));
			void calculation.trace.then(() => (traceReady = true));
			for (let tick = 0; tick < 10; tick++) {
				await vi.advanceTimersByTimeAsync(10_000);
				worker.emit({ type: 'heartbeat' });
			}
			expect(outcomeReady).toBe(false);
			expect(worker.terminate).not.toHaveBeenCalled();
			worker.emit({ type: 'result', outcome: expected });
			expect(await calculation.outcome).toEqual(expected);
			await vi.advanceTimersByTimeAsync(60_000);
			expect(traceReady).toBe(false);
			expect(worker.terminate).not.toHaveBeenCalled();
			worker.emit({ type: 'artifacts', artifacts: {} });
			await calculation.trace;
			expect(await calculation.outcome).toEqual(expected);
			expect(worker.postMessage).toHaveBeenCalledOnce();
			expect(worker.terminate).toHaveBeenCalledOnce();
		} finally {
			vi.useRealTimers();
			vi.unstubAllGlobals();
		}
	});

	it('terminates an isolated worker that misses the liveness deadline with its incumbent', async () => {
		const incumbent = isPlan(
			await runInNonBrowser({
				horizon,
				balances: [balance('cp', 'cp', 2)],
				rules: [],
			}),
		);
		class HangingWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(): void {
				this.onmessage?.({
					data: { type: 'checkpoint', plan: incumbent },
				} as MessageEvent);
			}

			terminate(): void {
				terminated = true;
			}
		}
		let terminated = false;
		vi.stubGlobal('Worker', HangingWorker);
		vi.useFakeTimers();

		try {
			const resultPromise = planLeave({
				horizon,
				balances: [balance('cp', 'cp', 2)],
				rules: [],
				deadlineMs: 10,
			});
			await vi.advanceTimersByTimeAsync(30_000);
			const result = await resultPromise;
			expect(result.kind).toBe('PlanningIncomplete');
			if (result.kind === 'PlanningIncomplete') {
				expect(result.incumbent?.kind).toBe('Plan');
				expect(result.lastCompletedStage).toBe('dates');
				expect(result.reasons[0].code).toBe('worker-error');
			}
			expect(terminated).toBe(true);
		} finally {
			vi.useRealTimers();
			vi.unstubAllGlobals();
		}
	});

	it('keeps the delivered checkpoint prefix and recovers its explanation after watchdog failure', async () => {
		const core = await import('./leave-planner.core');
		const request = {
			horizon: { start: '2024-01-01', end: '2024-01-10' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		let checkpoint: PlanOutcome | undefined;
		let checkpointState: PlanningTraceState | undefined;
		const expected = core.calculatePlanningInternal(request, (plan, state) => {
			checkpoint = plan;
			checkpointState = state;
		});
		expect(expected.kind).toBe('Plan');
		if (expected.kind !== 'Plan' || !checkpointState) return;
		checkpoint = {
			...expected,
			completedStages: ['validation', 'obligations', 'at-risk'],
			lastCompletedStage: 'at-risk',
		};
		const initialState: PlanningTraceState = {
			horizon: request.horizon,
			balances: [
				{
					id: 'cp',
					type: 'cp',
					quantity: 1,
					remaining: 1,
					availableFrom: '2024-01-01',
					expiryDate: '2024-12-31',
					earned: false,
				},
			],
			placements: [],
			earnedActivations: [],
		};
		const prefix: PlanningTraceUpdate = {
			initialState,
			operations: [
				{
					kind: 'phase',
					phase: {
						id: 'phase:1',
						name: 'dates',
						completed: false,
						status: 'interrupted',
					},
				},
				{
					kind: 'decision',
					phaseId: 'phase:1',
					decision: { id: 'decision:1', action: 'choose', dates: ['2024-01-02'] },
				},
				{
					kind: 'candidate',
					phaseId: 'phase:1',
					decisionId: 'decision:1',
					index: 0,
					mode: 'append',
					candidate: { status: 'evaluated-rejected', date: '2024-01-02' },
				},
			],
		};
		const workers: Array<{ terminated: boolean }> = [];
		class RecoveringWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;
			terminated = false;

			constructor() {
				workers.push(this);
			}

			postMessage(
				message:
					| { type: 'plan' }
					| {
							type: 'explain-checkpoint';
							request: unknown;
							plan: PlanOutcome;
							state: PlanningTraceState;
							interruption: PlanningReason;
					  },
			): void {
				if (message.type === 'plan') {
					queueMicrotask(() => {
						this.onmessage?.({
							data: { type: 'checkpoint', plan: checkpoint, state: checkpointState },
						} as MessageEvent);
						this.onmessage?.({
							data: { type: 'trace-update', totalMs: 0, update: prefix },
						} as MessageEvent);
					});
					return;
				}
				if (message.type === 'explain-checkpoint')
					queueMicrotask(() => {
						const recovered = core.explainIncompleteCheckpoint(
							message.request,
							message.plan,
							message.state,
							message.interruption,
						);
						this.onmessage?.({
							data: { type: 'explanation', ...recovered },
						} as MessageEvent);
					});
			}

			terminate(): void {
				this.terminated = true;
			}
		}
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', RecoveringWorker);
		vi.useFakeTimers();
		try {
			const calculation = createPlanningCalculation({ ...request, deadlineMs: 20 });
			await vi.runAllTicks();
			await vi.advanceTimersByTimeAsync(30_000);
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('PlanningIncomplete');
			if (outcome.kind === 'PlanningIncomplete')
				expect(outcome.incumbent).toEqual(checkpoint);
			const trace = await calculation.trace;
			expect(trace?.status).toBe('failed');
			expect(trace?.error?.code).toBe('worker-error');
			expect(trace?.phases[0].decisions[0].candidates).toHaveLength(1);
			const explanation = await calculation.explanation;
			expect(explanation?.kind).toBe('PlanExplanation');
			if (explanation?.kind === 'PlanExplanation')
				expect(explanation.incomplete?.reason.code).toBe('worker-error');
			expect((await calculation.explanationError)?.code).toBe('worker-error');
			expect(workers).toHaveLength(2);
			expect(workers.every((worker) => worker.terminated)).toBe(true);
		} finally {
			vi.useRealTimers();
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('reports no completed stage when an isolated worker never checkpoints', async () => {
		class SilentWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(): void {
				// Deliberately never checkpoint or finish.
			}

			terminate(): void {}
		}
		vi.stubGlobal('Worker', SilentWorker);
		vi.useFakeTimers();
		try {
			const resultPromise = planLeave({
				horizon,
				balances: [balance('cp', 'cp', 2)],
				rules: [],
				deadlineMs: 10,
			});
			await vi.advanceTimersByTimeAsync(30_000);
			const result = await resultPromise;
			expect(result.kind).toBe('PlanningIncomplete');
			if (result.kind === 'PlanningIncomplete') {
				expect(result.incumbent).toBeUndefined();
				expect(result.completedStages).toEqual([]);
				expect(result.lastCompletedStage).toBeUndefined();
				expect(result.reasons[0].code).toBe('worker-error');
			}
		} finally {
			vi.useRealTimers();
			vi.unstubAllGlobals();
		}
	});

	it('does not let excluded trace transfer time consume worker liveness before the outcome', async () => {
		const expected = isPlan(
			await runInNonBrowser({ horizon, balances: [balance('cp', 'cp', 1)], rules: [] }),
		);
		class TraceAwareWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(): void {
				this.onmessage?.({ data: { type: 'trace-overhead', totalMs: 0 } } as MessageEvent);
				setTimeout(() => {
					this.onmessage?.({
						data: { type: 'trace-overhead', totalMs: 300 },
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'artifacts', artifacts: {} },
					} as MessageEvent);
				}, 300);
			}

			terminate(): void {}
		}
		vi.stubGlobal('Worker', TraceAwareWorker);
		try {
			expect(
				await planLeave({
					horizon,
					balances: [balance('cp', 'cp', 1)],
					rules: [],
					deadlineMs: 100,
				}),
			).toEqual(expected);
		} finally {
			vi.unstubAllGlobals();
		}
	});

	it.each([undefined, 25_000])(
		'sends a detached, callback-free request with budget %s',
		async (deadlineMs) => {
			const sourceDate = new Date('2024-01-01T00:00:00Z');
			const request = {
				deadlineMs,
				horizon: { start: sourceDate, end: '2025-01-01' },
				balances: [
					{
						id: 'cp',
						type: 'cp' as const,
						quantity: 0,
						availableFrom: sourceDate,
						expiryDate: '2025-01-01',
					},
				],
				rules: [],
			};
			const expected = isPlan(await runInNonBrowser(request));
			let posted: { type: string; request: PlanningRequest } | undefined;
			class InspectingWorker {
				onmessage: ((event: MessageEvent) => void) | null = null;
				onerror: (() => void) | null = null;

				postMessage(message: { type: string; request: PlanningRequest }): void {
					posted = structuredClone(message);
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
				}

				terminate(): void {}
			}
			vi.stubGlobal('Worker', InspectingWorker);
			try {
				const result = await planLeave(request);
				expect(result.kind).toBe('Plan');
				expect(posted?.request).not.toBe(request);
				expect(posted?.request.deadlineMs).toBe(deadlineMs);
				expect(posted?.request.progress).toBeUndefined();
				expect(request.horizon.start).toBe(sourceDate);
			} finally {
				vi.unstubAllGlobals();
			}
		},
	);

	it('strips legacy aliases at the worker boundary', async () => {
		const request = {
			horizon,
			balances: [
				{
					id: 'cp',
					type: 'cp',
					quantity: 1,
					expiryDate: '2025-01-01',
					numberOfDays: 99,
					availabilityDate: '2024-01-01',
				},
			],
			rules: [],
		} as unknown as PlanningRequest;
		let posted: { type: string; request: PlanningRequest } | undefined;
		class InspectingWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(message: { type: string; request: PlanningRequest }): void {
				posted = structuredClone(message);
				this.onmessage?.({
					data: { type: 'result', outcome: { kind: 'Plan' } },
				} as MessageEvent);
			}

			terminate(): void {}
		}
		vi.stubGlobal('Worker', InspectingWorker);
		try {
			await planLeave(request);
			expect(posted?.request.balances[0]).toEqual({
				id: 'cp',
				type: 'cp',
				quantity: 1,
				availableFrom: undefined,
				expiryDate: '2025-01-01',
			});
		} finally {
			vi.unstubAllGlobals();
		}
	});
});

describe('planning calculation context', () => {
	it('explains fixed rule credits without debit and keeps them in comparisons after the inputs change', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const submitted: PlanningRequest = {
				horizon: { start: '2024-01-08', end: '2024-01-20' },
				balances: [balance('remaining-cp', 'cp', 1, '2025-01-01')],
				declaredDays: [{ date: '2024-01-10', type: 'cp' }],
				labels: { exact: 'Two CP including Wednesday', preferred: 'Two days this week' },
				rules: [
					{ id: 'exact', force: 'obligation', placeType: 'cp' },
					{ id: 'preferred', force: 'preference', placeType: 'any' },
				].map((rule) => ({
					...rule,
					type: 'time_window',
					startDate: '2024-01-08',
					endDate: '2024-01-12',
					placeDays: 2,
				})),
			};
			const originalDeclarations = structuredClone(submitted.declaredDays);
			const calculation = createPlanningCalculation(submitted);
			submitted.declaredDays![0].date = '2024-01-11';
			submitted.declaredDays![0].type = 'rtt';
			submitted.rules[0].placeDays = 4;
			if ('endDate' in submitted.rules[0]) submitted.rules[0].endDate = '2024-01-19';
			submitted.horizon.end = '2024-01-11';
			submitted.labels = { exact: 'Edited later' };
			const outcome = isPlan(await calculation.outcome);
			expect(outcome.placements).toHaveLength(1);
			expect(outcome.remainingBalances).toEqual([]);
			expect(outcome.preferences).toMatchObject([{ requested: 2, satisfied: 2 }]);
			expect(outcome.timeWindowContributions).toEqual([
				{
					ruleId: 'exact',
					label: 'Two CP including Wednesday',
					requested: 2,
					declaredDays: originalDeclarations,
					placementDates: [outcome.placements[0].date],
				},
				{
					ruleId: 'preferred',
					label: 'Two days this week',
					requested: 2,
					declaredDays: originalDeclarations,
					placementDates: [outcome.placements[0].date],
				},
			]);
			const explanation = await calculation.explanation;
			if (explanation?.kind !== 'PlanExplanation')
				throw new Error('Expected a stable explanation.');
			expect(explanation.timeWindowContributions).toEqual(outcome.timeWindowContributions);
			expect(explanation.placements).toHaveLength(1);
			expect(explanation.placements[0].comparison).toMatchObject({
				before: {
					objectives: expect.arrayContaining([
						expect.objectContaining({ id: 'obligation-validity', value: 1 }),
						expect.objectContaining({ id: 'preference:preferred', value: 1 }),
					]),
				},
				after: {
					objectives: expect.arrayContaining([
						expect.objectContaining({ id: 'obligation-validity', value: 0 }),
						expect.objectContaining({ id: 'preference:preferred', value: 2 }),
					]),
				},
			});
			const trace = await calculation.trace;
			expect(trace?.initialState.declaredDays).toEqual(originalDeclarations);
			const deltas =
				trace?.phases.flatMap((phase) =>
					phase.decisions.flatMap((decision) => decision.deltas),
				) ?? [];
			const placements = deltas.filter((delta) => delta.kind === 'placement-added');
			expect(placements.length).toBeGreaterThan(0);
			for (const delta of placements) {
				expect(delta.placement?.date).not.toBe('2024-01-10');
			}
			const debits = deltas.filter(
				(delta) =>
					delta.kind === 'balance-changed' &&
					delta.remainingBefore! > delta.remainingAfter!,
			);
			expect(debits.length).toBeGreaterThan(0);
			for (const debit of debits)
				expect(debit.remainingBefore! - debit.remainingAfter!).toBe(1);
			const before = structuredClone(outcome);
			const analysis = await calculation.analyzeCounterfactual(outcome.placements[0]);
			expect(analysis.results.find(({ date }) => date === '2024-01-10')).toMatchObject({
				status: 'ineligible',
				reason: { code: 'declared-day' },
			});
			expect(analysis.results.find(({ date }) => date === '2024-01-15')).toMatchObject({
				status: 'ineligible',
				reason: { code: 'rule-invalid' },
			});
			expect(analysis.results.find(({ date }) => date === '2024-01-11')).toMatchObject({
				status: 'eligible',
				comparison: {
					after: {
						objectives: expect.arrayContaining([
							expect.objectContaining({ id: 'obligation-validity', value: 0 }),
							expect.objectContaining({ id: 'preference:preferred', value: 2 }),
						]),
					},
				},
			});
			expect(
				analysis.results.find(({ date }) => date === outcome.placements[0].date)?.comparison
					?.after,
			).toEqual(explanation.placements[0].objectiveVector);
			expect(outcome).toEqual(before);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps a cross-year declared extension in stable explanations and restored date comparisons', async () => {
		const { isWorkingPlanningDate } = await import('./declared-non-working-days');
		const { addPlanningDays } = await import('./planning-date');
		const declaredDays: NonNullable<PlanningRequest['declaredDays']>[number][] = [];
		for (let date = '2024-12-31'; date < '2026-01-06'; date = addPlanningDays(date, 1))
			if (isWorkingPlanningDate(date)) declaredDays.push({ date, type: 'other' });
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-12-30', end: '2024-12-31' },
				balances: [
					{ ...balance('cp', 'cp', 1, '2024-12-30'), availableFrom: '2024-12-30' },
				],
				rules: [],
				declaredDays,
			});
			const outcome = isPlan(await calculation.outcome);
			expect(outcome.timeOffPeriods[0]).toMatchObject({
				start: '2024-12-28',
				end: '2026-01-05',
			});
			expect(outcome.timeOffPeriods[0].nonWorkingDates).toContain('2026-01-01');
			const explanation = await calculation.explanation;
			if (explanation?.kind !== 'PlanExplanation')
				throw new Error('Expected a stable plan explanation.');
			expect(explanation.timeOffPeriods).toEqual(outcome.timeOffPeriods);
			const analysis = await calculation.analyzeCounterfactual(outcome.placements[0]);
			expect(analysis.results[0].comparison?.after).toEqual(
				explanation.placements[0].objectiveVector,
			);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps declared periods and objective comparisons tied to the same snapshot after current inputs change', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const submitted: PlanningRequest = {
				horizon: { start: '2026-11-01', end: '2026-12-01' },
				balances: [balance('cp', 'cp', 2, '2026-11-30')],
				rules: [],
				declaredDays: [
					{ date: '2026-11-09', type: 'other' },
					{ date: '2026-11-10', type: 'rtt' },
				],
			};
			const original = structuredClone(submitted.declaredDays);
			const calculation = createPlanningCalculation(submitted);
			submitted.declaredDays![0].date = '2026-11-20';
			submitted.declaredDays![0].type = 'cp';
			submitted.horizon.end = '2026-11-12';
			const outcome = isPlan(await calculation.outcome);
			const explanation = await calculation.explanation;
			if (explanation?.kind !== 'PlanExplanation')
				throw new Error('Expected a stable plan explanation.');
			expect(explanation.declaredDays).toEqual(original);
			expect(explanation.timeOffPeriods).toEqual(outcome.timeOffPeriods);
			for (const placement of explanation.placements) {
				expect(placement.timeOffPeriod).toEqual(outcome.timeOffPeriods[0]);
				expect(placement.finalMetrics).toEqual(outcome.metrics);
				expect(placement.firstDecisiveObjective).toBe('unplaced-at-risk');
			}
			const trace = await calculation.trace;
			expect(trace?.initialState.declaredDays).toEqual(original);
			const evaluated = trace?.phases.flatMap((phase) =>
				phase.decisions.flatMap((decision) => decision.candidates),
			);
			const fixedDates = new Set(original?.map(({ date }) => date));
			for (const candidate of evaluated?.filter(({ status }) => status === 'chosen') ?? [])
				expect(
					(candidate.dates ?? [candidate.date]).some(
						(date) => date && fixedDates.has(date),
					),
				).toBe(false);
			expect(
				evaluated?.some(
					(candidate) =>
						candidate.comparison?.after.objectives.some(
							(objective) =>
								objective.id === 'holiday-week-value' && objective.value === 3,
						) &&
						candidate.comparison.after.objectives.some(
							(objective) =>
								objective.id === 'non-working-day-gain' && objective.value === 5,
						),
				),
			).toBe(true);
			const before = structuredClone(outcome);
			const analysis = await calculation.analyzeCounterfactual(outcome.placements[0]);
			const restored = analysis.results.find(
				({ date }) => date === outcome.placements[0].date,
			);
			expect(restored?.comparison?.after).toEqual(explanation.placements[0].objectiveVector);
			const alternative = analysis.results.find(({ date }) => date === '2026-11-20');
			expect(alternative?.status).toBe('eligible');
			expect(alternative?.comparison?.after.objectives).toContainEqual(
				expect.objectContaining({ id: 'holiday-week-value', value: 0 }),
			);
			expect(alternative?.comparison?.after.objectives).toContainEqual(
				expect.objectContaining({ id: 'non-working-day-gain', value: 7 }),
			);
			expect(outcome).toEqual(before);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('detaches declared dates and types across results, explanations, trace and comparisons', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const submitted: PlanningRequest = {
				horizon: { start: '2024-01-02', end: '2024-02-01' },
				balances: [balance('cp', 'cp', 4, '2024-01-05')],
				rules: [],
				declaredDays: [
					{ date: '2024-01-02', type: 'cp' },
					{ date: '2024-01-03', type: 'rtt' },
					{ date: '2024-01-05', type: 'other' },
				],
			};
			const original = structuredClone(submitted.declaredDays);
			const calculation = createPlanningCalculation(submitted);
			submitted.declaredDays![0].type = 'other';
			submitted.horizon.end = '2024-01-03';
			expect(calculation.snapshot.declaredDays).toEqual(original);
			expect(Object.isFrozen(calculation.snapshot.declaredDays![0])).toBe(true);
			const outcome = isPlan(await calculation.outcome);
			expect(outcome.declaredDays).toEqual(original);
			expect(outcome.placements.map(({ date }) => date)).toEqual(['2024-01-04']);
			expect(await calculation.explanation).toMatchObject({
				kind: 'PlanExplanation',
				declaredDays: original,
				placements: [{ placement: { date: '2024-01-04' } }],
			});
			const trace = await calculation.trace;
			expect(trace?.initialState.declaredDays).toEqual(original);
			expect(trace?.nonWorkingDates).toContainEqual({
				date: '2024-01-02',
				reason: expect.objectContaining({ code: 'declared-day' }),
			});
			const frozenOutcome = structuredClone(outcome);
			const analysis = await calculation.analyzeCounterfactual(outcome.placements[0]);
			for (const { date } of original!)
				expect(analysis.results.find((result) => result.date === date)).toMatchObject({
					status: 'ineligible',
					reason: { code: 'declared-day' },
					historicalStatus: 'ineligible',
				});
			expect(outcome).toEqual(frozenOutcome);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps a multi-year horizon attached to its immutable outcome, explanation and original trace', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const request = {
				horizon: { start: '2024-01-01', end: '2027-01-01' },
				balances: [
					{
						id: 'cp',
						type: 'cp',
						quantity: 1,
						availableFrom: '2026-12-24',
						expiryDate: '2026-12-24',
					},
				],
				rules: [
					{
						id: 'final-year',
						type: 'time_window',
						force: 'obligation',
						startDate: '2026-12-24',
						endDate: '2026-12-24',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			};
			const calculation = createPlanningCalculation(request);
			request.horizon.end = '2025-01-01';
			request.balances[0].expiryDate = '2024-12-31';
			expect(calculation.snapshot.horizon).toEqual({
				start: '2024-01-01',
				end: '2027-01-01',
			});
			expect(isPlan(await calculation.outcome).horizon).toEqual(calculation.snapshot.horizon);
			const explanation = await calculation.explanation;
			expect(explanation?.kind).toBe('PlanExplanation');
			if (explanation?.kind === 'PlanExplanation')
				expect(explanation.placements[0]).toMatchObject({
					placement: { date: '2026-12-24', balanceId: 'cp', ruleIds: ['final-year'] },
					balance: { availableFrom: '2026-12-24', expiryDate: '2026-12-24' },
				});
			expect((await calculation.trace)?.initialState.horizon).toEqual(
				calculation.snapshot.horizon,
			);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('replays full balance metadata when an existing balance changes', () => {
		const state = {
			balances: [
				{
					id: 'earned:producer:2024-01-04',
					type: 'rtt' as const,
					quantity: 0,
					remaining: 0,
					availableFrom: '2024-01-01',
					expiryDate: '2024-12-31',
					earned: false,
				},
			],
			placements: new Map(),
			earnedActivations: [],
		};

		applyReplayDeltas(state, [
			{
				kind: 'balance-changed',
				balanceId: 'earned:producer:2024-01-04',
				remainingBefore: 0,
				remainingAfter: 1,
				balance: {
					id: 'earned:producer:2024-01-04',
					type: 'rtt',
					quantity: 1,
					remaining: 1,
					availableFrom: '2024-01-05',
					expiryDate: '2024-12-31',
					earned: true,
					sourceRuleId: 'producer',
				},
			},
		]);

		expect(state.balances[0]).toEqual({
			id: 'earned:producer:2024-01-04',
			type: 'rtt',
			quantity: 1,
			remaining: 1,
			availableFrom: '2024-01-05',
			expiryDate: '2024-12-31',
			earned: true,
			sourceRuleId: 'producer',
		});
	});

	it('applies placement delta balance changes to the replayed balance', () => {
		const state = {
			balances: [
				{
					id: 'cp',
					type: 'cp' as const,
					quantity: 1,
					remaining: 1,
					availableFrom: '2024-01-01',
					expiryDate: '2024-12-31',
					earned: false,
				},
			],
			placements: new Map(),
			earnedActivations: [],
		};

		applyReplayDeltas(state, [
			{
				kind: 'placement-added',
				balanceId: 'cp',
				remainingBefore: 1,
				remainingAfter: 0,
				placement: {
					date: '2024-01-04',
					balanceId: 'cp',
					type: 'cp',
					ruleIds: [],
					supporting: false,
				},
			},
		]);

		expect(state.balances[0]).toEqual({
			id: 'cp',
			type: 'cp',
			quantity: 1,
			remaining: 0,
			availableFrom: '2024-01-01',
			expiryDate: '2024-12-31',
			earned: false,
		});
	});

	it('keeps the planning outcome identical when trace instrumentation is enabled', async () => {
		const core = await import('./leave-planner.core');
		const request = {
			horizon: { start: '2024-01-01', end: '2024-02-01' },
			balances: [balance('cp', 'cp', 3, '2024-01-31')],
			rules: [],
		};
		const withoutTrace = core.calculatePlanningInternal(request);
		let traceStatus: string | undefined;
		const withTrace = core.calculatePlanningInternal(request, undefined, (artifacts) => {
			traceStatus = artifacts.trace?.status;
		});

		expect(withTrace).toEqual(withoutTrace);
		expect(traceStatus).toBe('ready');
	});

	it('keeps an immutable submitted snapshot beside the outcome', async () => {
		const request = {
			horizon,
			balances: [balance('cp', 'cp', 1)],
			rules: [],
			labels: { cp: 'Paid leave' },
		};
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation(request);
			request.balances[0].quantity = 99;
			request.labels.cp = 'Changed later';

			expect(calculation.snapshot.balances[0].quantity).toBe(1);
			expect(calculation.snapshot.labels['cp']).toBe('Paid leave');
			expect((await calculation.outcome).kind).toBe('Plan');
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('lets validation reject an invalid Date in the submitted horizon', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: new Date(Number.NaN), end: '2025-01-01' },
				balances: [],
				rules: [],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('InvalidInput');
			if (outcome.kind === 'InvalidInput')
				expect(outcome.reasons[0].code).toBe('horizon-start');
			expect(calculation.snapshot.horizon.start).toBe('Invalid Date');
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('materializes a chronological explanation after the unchanged outcome', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-15' },
				balances: [
					{
						...balance('cp', 'cp', 1, '2026-01-01'),
						name: 'Paid leave entitlement',
					},
				],
				rules: [
					{
						id: 'winter',
						name: 'Winter break',
						type: 'time_window',
						startDate: '2024-01-02',
						endDate: '2024-01-12',
						placeDays: 1,
						placeType: 'cp',
					},
				],
				labels: { winter: 'Winter break' },
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan') return;
			expect('explanation' in outcome).toBe(false);
			const explanation = await calculation.explanation;
			expect(explanation?.kind).toBe('PlanExplanation');
			if (explanation?.kind !== 'PlanExplanation') return;
			expect(explanation.placements).toHaveLength(outcome.placements.length);
			expect(explanation.placements[0].balance?.name).toBe('Paid leave entitlement');
			expect(explanation.placements[0].ruleIds).toContain('winter');
			expect(explanation.placements[0].objectiveVector.objectives.length).toBeGreaterThan(1);
			expect('score' in explanation.placements[0].objectiveVector).toBe(false);
			expect(explanation.placements[0].firstDecisiveObjective).toBe(
				explanation.placements[0].comparison.firstDecisiveObjective,
			);
			expect(explanation.placements[0].firstDecisiveObjective).toBe('preference:winter');
			const alternatives = await calculation.analyzeCounterfactual(outcome.placements[0]);
			expect(alternatives.kind).toBe('Counterfactual');
			if (alternatives.kind === 'Counterfactual')
				expect(
					alternatives.results.find(
						(result) => result.date === outcome.placements[0].date,
					)?.comparison?.firstDecisiveObjective,
				).toBe('preference:winter');
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('reports every rule contribution when one placement is shared', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-06' },
				balances: [balance('cp', 'cp', 1)],
				rules: [
					{
						id: 'wide',
						name: 'Wide window',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-02',
						endDate: '2024-01-05',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'exact',
						name: 'Exact day',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-05',
						endDate: '2024-01-05',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			const explanation = await calculation.explanation;
			expect(explanation?.kind).toBe('PlanExplanation');
			if (explanation?.kind !== 'PlanExplanation') return;
			expect(
				explanation.placements[0].contributions
					.filter((contribution) => contribution.kind === 'rule')
					.map((contribution) => contribution.ruleId),
			).toEqual(['exact', 'wide']);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('compares the selected placement across the half-open horizon without changing the plan', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-10' },
				balances: [balance('cp', 'cp', 1, '2024-12-31')],
				rules: [],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan') return;
			const before = structuredClone(outcome);
			const analysis = await calculation.analyzeCounterfactual(outcome.placements[0]);
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(analysis.results).toHaveLength(9);
			expect(analysis.results.some((result) => result.reason?.code === 'non-working')).toBe(
				true,
			);
			expect(
				analysis.results.some(
					(result) => result.status === 'eligible' && result.comparison,
				),
			).toBe(true);
			expect(outcome).toEqual(before);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps every mandatory IF_THEN occurrence satisfied in counterfactuals', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-04-25', end: '2024-05-15' },
				balances: [balance('cp', 'cp', 2, '2024-12-31')],
				rules: [
					{
						id: 'wednesday-holidays',
						type: 'if_then',
						force: 'obligation',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'auto',
						rewardDays: 0,
					},
				],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan') return;
			const firstOccurrence = outcome.placements.find(
				(placement) => placement.date < '2024-05-05',
			);
			const secondOccurrence = outcome.placements.find(
				(placement) => placement.date > '2024-05-05',
			);
			expect(firstOccurrence).toBeDefined();
			expect(secondOccurrence).toBeDefined();
			if (!firstOccurrence || !secondOccurrence) return;

			const alternateSecondDate =
				secondOccurrence.date === '2024-05-07' ? '2024-05-09' : '2024-05-07';
			const analysis = await calculation.analyzeCounterfactual(firstOccurrence);
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(
				analysis.results.find((result) => result.date === alternateSecondDate),
			).toMatchObject({
				status: 'ineligible',
				reason: { code: 'rule-invalid' },
			});
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('allows trace counterfactuals while later obligations are still pending', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-05-01', end: '2024-05-10' },
				balances: [balance('cp', 'cp', 2, '2024-12-31')],
				rules: [
					{
						id: 'early-window',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-02',
						endDate: '2024-05-03',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'late-window',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-05-06',
						endDate: '2024-05-07',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			});
			const outcome = await calculation.outcome;
			const trace = await calculation.trace;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan' || !trace) return;
			const earlyPlacement = outcome.placements.find((placement) =>
				placement.ruleIds.includes('early-window'),
			);
			expect(earlyPlacement).toBeDefined();
			if (!earlyPlacement) return;
			const decision = trace.phases
				.flatMap((phase) => phase.decisions)
				.find((candidate) =>
					candidate.deltas.some(
						(delta) =>
							delta.kind === 'placement-added' &&
							delta.placement?.ruleIds.includes('early-window'),
					),
				);
			expect(decision).toBeDefined();
			if (!decision) return;

			const analysis = await calculation.analyzeCounterfactual({
				decisionId: decision.id,
				placement: earlyPlacement,
			});
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(
				['2024-05-02', '2024-05-03'].map(
					(date) => analysis.results.find((result) => result.date === date)?.status,
				),
			).toEqual(['eligible', 'eligible']);
			expect(
				analysis.results.find((result) => result.date === earlyPlacement.date)?.status,
			).toBe('eligible');
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('preserves supporting provenance in counterfactual placements', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-05', end: '2024-01-10' },
				balances: [balance('cp', 'cp', 1, '2025-01-01')],
				rules: [],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan') return;
			const selected = outcome.placements.find((placement) => placement.supporting);
			expect(selected).toBeDefined();
			if (!selected) return;

			const analysis = await calculation.analyzeCounterfactual(selected);
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			const restored = analysis.results.find((result) => result.date === selected.date);
			expect(
				restored?.comparison?.after.objectives.find(
					(objective) => objective.id === 'supporting-placements',
				)?.value,
			).toBe(1);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('cancels superseded planning and trace workers without changing the latest result', async () => {
		const browserWindow = globalThis.window;
		const expected = isPlan(
			await runInNonBrowser({
				horizon: { start: '2024-01-01', end: '2024-01-10' },
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			}),
		);
		const trace = {
			status: 'ready' as const,
			initialState: {
				horizon: expected.horizon,
				balances: [],
				placements: [],
				earnedActivations: [],
			},
			phases: [],
			completedStages: [],
		};
		const workers: Array<{ terminated: boolean }> = [];
		class SupersededWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;
			terminated = false;

			constructor() {
				workers.push(this);
			}

			postMessage(): void {
				if (workers.length === 2) {
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
					return;
				}
				if (workers.length !== 3) return;
				queueMicrotask(() => {
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'artifacts', artifacts: { trace } },
					} as MessageEvent);
				});
			}

			terminate(): void {
				this.terminated = true;
			}
		}
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', SupersededWorker);
		try {
			const pending = createPlanningCalculation({
				horizon: expected.horizon,
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			});
			const materializing = createPlanningCalculation({
				horizon: expected.horizon,
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			});
			const latest = createPlanningCalculation({
				horizon: expected.horizon,
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			});

			expect(workers).toHaveLength(3);
			expect(workers[0].terminated).toBe(true);
			expect(workers[1].terminated).toBe(true);
			const pendingOutcome = await pending.outcome;
			expect(pendingOutcome.kind).toBe('PlanningIncomplete');
			if (pendingOutcome.kind === 'PlanningIncomplete')
				expect(pendingOutcome.reasons[0].code).toBe('stale-calculation');
			expect((await pending.trace)?.error?.code).toBe('stale-calculation');
			expect(await materializing.outcome).toEqual(expected);
			expect((await materializing.trace)?.error?.code).toBe('stale-calculation');
			expect(await materializing.explanationError).toBeUndefined();
			expect(await latest.outcome).toEqual(expected);
			expect((await latest.trace)?.status).toBe('ready');
			expect(workers[2].terminated).toBe(true);
		} finally {
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('discards counterfactual work from an older calculation', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const older = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-10' },
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			});
			const olderOutcome = await older.outcome;
			expect(olderOutcome.kind).toBe('Plan');
			if (olderOutcome.kind !== 'Plan') return;
			createPlanningCalculation({ horizon, balances: [], rules: [] });

			const analysis = await older.analyzeCounterfactual(olderOutcome.placements[0]);
			expect(analysis.kind).toBe('CounterfactualStale');
			expect(analysis.results).toEqual([]);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps counterfactual worker failures local and allows a clean retry', async () => {
		const request = {
			horizon: { start: '2024-01-01', end: '2024-01-10' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		const expected = isPlan(await runInNonBrowser(request));
		const selected = expected.placements[0];
		const trace = {
			status: 'ready' as const,
			initialState: {
				horizon: expected.horizon,
				balances: [],
				placements: [],
				earnedActivations: [],
			},
			phases: [],
			completedStages: expected.completedStages,
		};
		const response: CounterfactualAnalysis = {
			kind: 'Counterfactual',
			calculationId: 'transport-test',
			placement: selected,
			hypothetical: true,
			baseline: { objectives: [] },
			results: [],
		};
		let counterfactualCalls = 0;
		class RetriableWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;
			terminated = false;

			postMessage(message: { type: string }): void {
				if (message.type === 'plan') {
					queueMicrotask(() => {
						this.onmessage?.({
							data: { type: 'result', outcome: expected },
						} as MessageEvent);
						this.onmessage?.({
							data: {
								type: 'explanation',
								explanation: { kind: 'PlanExplanation', placements: [] },
							},
						} as MessageEvent);
						this.onmessage?.({
							data: {
								type: 'artifacts-start',
								artifacts: {},
								trace,
							},
						} as MessageEvent);
						this.onmessage?.({ data: { type: 'artifacts-complete' } } as MessageEvent);
					});
					return;
				}
				counterfactualCalls++;
				queueMicrotask(() => {
					if (counterfactualCalls === 1)
						this.onmessage?.({
							data: {
								type: 'error',
								code: 'counterfactual-error',
								message: 'Counterfactual analysis failed locally.',
							},
						} as MessageEvent);
					else
						this.onmessage?.({
							data: { type: 'counterfactual-result', analysis: response },
						} as MessageEvent);
				});
			}

			terminate(): void {
				this.terminated = true;
			}
		}
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', RetriableWorker);
		try {
			const calculation = createPlanningCalculation(request);
			expect(await calculation.outcome).toEqual(expected);
			await calculation.trace;
			await expect(calculation.analyzeCounterfactual(selected)).rejects.toThrow(
				'Counterfactual analysis failed locally.',
			);
			const analysis = await calculation.analyzeCounterfactual(selected);
			expect(analysis.kind).toBe('Counterfactual');
			expect(analysis.calculationId).toBe(calculation.id);
			expect(counterfactualCalls).toBe(2);
		} finally {
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('terminates an active counterfactual worker when a newer calculation starts', async () => {
		const request = {
			horizon: { start: '2024-01-01', end: '2024-01-10' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		const expected = isPlan(await runInNonBrowser(request));
		const trace = {
			status: 'ready' as const,
			initialState: {
				horizon: expected.horizon,
				balances: [],
				placements: [],
				earnedActivations: [],
			},
			phases: [],
			completedStages: expected.completedStages,
		};
		const workers: Array<{ terminated: boolean }> = [];
		class SupersededCounterfactualWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;
			terminated = false;

			constructor() {
				workers.push(this);
			}

			postMessage(message: { type: string }): void {
				if (message.type !== 'plan') return;
				queueMicrotask(() => {
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'artifacts-start', artifacts: {}, trace },
					} as MessageEvent);
					this.onmessage?.({ data: { type: 'artifacts-complete' } } as MessageEvent);
				});
			}

			terminate(): void {
				this.terminated = true;
			}
		}
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', SupersededCounterfactualWorker);
		try {
			const previous = createPlanningCalculation(request);
			await previous.outcome;
			await previous.trace;
			const pendingAnalysis = previous.analyzeCounterfactual(expected.placements[0]);
			await vi.waitFor(() => expect(workers).toHaveLength(2));
			const latest = createPlanningCalculation(request);
			const stale = await pendingAnalysis;
			expect(stale.kind).toBe('CounterfactualStale');
			expect(workers[1].terminated).toBe(true);
			expect((await latest.outcome).kind).toBe('Plan');
		} finally {
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps earned-entitlement availability and provenance in counterfactuals', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-04-25', end: '2024-05-15' },
				balances: [balance('cp', 'cp', 2), balance('rtt', 'rtt', 0, '2026-01-01')],
				rules: [
					{
						id: 'wednesday-holidays',
						type: 'if_then',
						force: 'obligation',
						dayOfWeek: 3,
						placeDays: 1,
						placeType: 'cp',
						placement: 'after',
						rewardDays: 1,
						rewardType: 'rtt',
					},
					{
						id: 'thursday-consumer',
						type: 'if_then',
						force: 'obligation',
						dayOfWeek: 4,
						placeDays: 1,
						placeType: 'rtt',
						placement: 'before',
						rewardDays: 0,
					},
				],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan') return;
			const earned = outcome.placements.find((placement) =>
				placement.balanceId.startsWith('earned:'),
			);
			expect(earned).toBeDefined();
			if (!earned) return;
			const analysis = await calculation.analyzeCounterfactual(earned);
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(analysis.placement).toEqual(earned);
			expect(
				analysis.results.find((result) => result.date === '2024-04-25')?.reason?.code,
			).toBe('unavailable');
			const trace = await calculation.trace;
			const earnedBalanceDelta = trace?.phases
				.flatMap((phase) => phase.decisions)
				.flatMap((decision) => decision.deltas)
				.find((delta) => delta.balance?.id === earned.balanceId);
			expect(earnedBalanceDelta?.balance).toMatchObject({
				id: earned.balanceId,
				type: earned.type,
				earned: true,
			});
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('replays a trace decision from its pre-decision state', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-02-01' },
				balances: [balance('cp', 'cp', 2, '2024-01-31')],
				rules: [
					{
						id: 'wide',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-01',
						endDate: '2024-01-31',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			});
			const outcome = await calculation.outcome;
			const trace = await calculation.trace;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan' || !trace) return;
			const decision = trace.phases
				.flatMap((phase) => phase.decisions)
				.find((candidate) =>
					candidate.deltas.some((delta) => delta.kind === 'placement-added'),
				);
			const placement = decision?.deltas.find(
				(delta) => delta.kind === 'placement-added',
			)?.placement;
			expect(decision).toBeDefined();
			expect(placement).toBeDefined();
			if (!decision || !placement) return;
			const laterPlacement = outcome.placements.find(
				(candidate) => candidate.date !== placement.date,
			);
			expect(laterPlacement).toBeDefined();
			if (!laterPlacement) return;

			const analysis = await calculation.analyzeCounterfactual({
				decisionId: decision.id,
				placement,
			});
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(
				analysis.results.find((result) => result.date === laterPlacement.date)?.status,
			).toBe('eligible');
			expect(
				analysis.results.find((result) => result.date === '2024-01-06')?.historicalStatus,
			).toBe('ineligible');
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps source-state ineligibility separate from unexamined trace history', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-11' },
				balances: [
					{
						...balance('cp', 'cp', 1, '2024-01-07'),
						availableFrom: '2024-01-04',
					},
				],
				rules: [],
			});
			const outcome = await calculation.outcome;
			const trace = await calculation.trace;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan' || !trace) return;
			const decision = trace.phases
				.flatMap((phase) => phase.decisions)
				.find((candidate) =>
					candidate.deltas.some(
						(delta) =>
							delta.kind === 'placement-added' &&
							delta.placement?.date === '2024-01-04',
					),
				);
			const placement = decision?.deltas.find(
				(delta) =>
					delta.kind === 'placement-added' && delta.placement?.date === '2024-01-04',
			)?.placement;
			expect(placement).toBeDefined();
			expect(decision).toBeDefined();
			if (!placement || !decision) return;

			const selection = { decisionId: decision.id, placement };
			const historicalEligibility = await calculation.historicalEligibility(selection);
			expect(historicalEligibility).toContainEqual({
				date: '2024-01-02',
				reason: expect.objectContaining({ code: 'unavailable' }),
			});
			expect(historicalEligibility).toContainEqual({
				date: '2024-01-08',
				reason: expect.objectContaining({ code: 'expired' }),
			});

			const analysis = await calculation.analyzeCounterfactual(selection);
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(analysis.results.find((result) => result.date === '2024-01-02')).toMatchObject({
				status: 'ineligible',
				historicalStatus: 'ineligible',
				reason: { code: 'unavailable' },
				historicalReason: { code: 'unavailable' },
			});
			expect(analysis.results.find((result) => result.date === '2024-01-08')).toMatchObject({
				status: 'ineligible',
				historicalStatus: 'ineligible',
				reason: { code: 'expired' },
				historicalReason: { code: 'expired' },
			});
			expect(analysis.results.find((result) => result.date === '2024-01-04')).toMatchObject({
				historicalStatus: 'chosen',
				historicalReason: undefined,
			});
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('replays branch-local ancestors without applying the selected decision twice', async () => {
		const request = {
			horizon: { start: '2024-01-01', end: '2024-01-10' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		const plan = isPlan(await runInNonBrowser(request));
		const firstPlacement = plan.placements[0];
		if (!firstPlacement) throw new Error('Expected the plan to contain a placement.');
		const selected = { ...firstPlacement, date: '2024-01-03' };
		const outcome = { ...plan, placements: [selected] };
		const committedPlacement = { ...selected, date: '2024-01-01' };
		const parentPlacement = { ...selected, date: '2024-01-02' };
		const initialState: PlanningTraceState = {
			horizon: request.horizon,
			balances: [
				{
					id: 'cp',
					type: 'cp',
					quantity: 5,
					remaining: 5,
					availableFrom: '2024-01-01',
					expiryDate: '2024-01-31',
					earned: false,
				},
			],
			placements: [],
			earnedActivations: [],
		};
		const committedDeltas = [
			{
				kind: 'placement-added' as const,
				date: committedPlacement.date,
				balanceId: 'cp',
				placement: committedPlacement,
			},
			{
				kind: 'balance-changed' as const,
				balanceId: 'cp',
				remainingBefore: 5,
				remainingAfter: 4,
				balance: {
					id: 'cp',
					type: 'cp' as const,
					quantity: 5,
					remaining: 4,
					availableFrom: '2024-01-02',
					expiryDate: '2024-01-31',
					earned: true,
					sourceRuleId: 'producer',
				},
			},
		];
		const parentDeltas = [
			{
				kind: 'placement-added' as const,
				date: parentPlacement.date,
				balanceId: 'cp',
				placement: parentPlacement,
			},
			{
				kind: 'balance-changed' as const,
				balanceId: 'cp',
				remainingBefore: 4,
				remainingAfter: 3,
			},
		];
		const selectedTransition = [
			{
				kind: 'placement-moved' as const,
				fromDate: parentPlacement.date,
				toDate: selected.date,
				date: selected.date,
				balanceId: 'cp',
				previousPlacement: parentPlacement,
				placement: selected,
			},
			{
				kind: 'balance-changed' as const,
				balanceId: 'cp',
				remainingBefore: 3,
				remainingAfter: 2,
			},
		];
		const update: PlanningTraceUpdate = {
			initialState,
			operations: [
				{
					kind: 'phase',
					phase: {
						id: 'obligations',
						name: 'obligations',
						completed: true,
						status: 'completed',
					},
				},
				{
					kind: 'decision',
					phaseId: 'obligations',
					decision: { id: 'committed', action: 'choose', dates: ['2024-01-01'] },
				},
				...committedDeltas.map((delta, index) => ({
					kind: 'delta' as const,
					phaseId: 'obligations',
					decisionId: 'committed',
					index,
					delta,
				})),
				{
					kind: 'decision',
					phaseId: 'obligations',
					decision: {
						id: 'branch-parent',
						action: 'choose',
						dates: [parentPlacement.date],
						branch: { deltas: parentDeltas },
					},
				},
				{
					kind: 'decision',
					phaseId: 'obligations',
					decision: {
						id: 'branch-selected',
						action: 'choose',
						dates: [selected.date],
						branch: {
							parentDecisionId: 'branch-parent',
							deltas: selectedTransition,
						},
					},
				},
				...selectedTransition.map((delta, index) => ({
					kind: 'delta' as const,
					phaseId: 'obligations',
					decisionId: 'branch-selected',
					index,
					delta,
				})),
				{
					kind: 'decision',
					phaseId: 'obligations',
					decision: {
						id: 'self-parent',
						action: 'choose',
						dates: [selected.date],
						branch: { parentDecisionId: 'self-parent', deltas: [] },
					},
				},
			],
		};
		const response: CounterfactualAnalysis = {
			kind: 'Counterfactual',
			calculationId: 'branch-transport-test',
			placement: selected,
			hypothetical: true,
			baseline: { objectives: [] },
			results: [],
		};
		let receivedState: PlanningTraceState | undefined;
		let receivedOptions: CounterfactualBaselineOptions | undefined;
		class BranchTraceWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(message: {
				type: string;
				state?: PlanningTraceState;
				options?: CounterfactualBaselineOptions;
			}): void {
				if (message.type === 'plan') {
					this.onmessage?.({ data: { type: 'result', outcome } } as MessageEvent);
					this.onmessage?.({
						data: {
							type: 'artifacts-start',
							artifacts: {},
							trace: {
								status: 'ready',
								initialState,
								phases: [],
								completedStages: outcome.completedStages,
								nonWorkingDates: [],
								error: undefined,
							},
						},
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'trace-update', totalMs: 0, update },
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'artifacts-complete', traceTransferMs: 0 },
					} as MessageEvent);
					return;
				}
				receivedState = message.state;
				receivedOptions = message.options;
				if (message.type === 'historical-eligibility') {
					queueMicrotask(() =>
						this.onmessage?.({
							data: {
								type: 'historical-eligibility-result',
								entries: [
									{
										date: '2024-01-03',
										reason: {
											code: 'unavailable',
											message:
												'The selected entitlement is not available yet.',
										},
									} satisfies HistoricalEligibilityReason,
								],
							},
						} as MessageEvent),
					);
					return;
				}
				queueMicrotask(() =>
					this.onmessage?.({
						data: { type: 'counterfactual-result', analysis: response },
					} as MessageEvent),
				);
			}

			terminate(): void {}
		}
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', BranchTraceWorker);
		try {
			const calculation = createPlanningCalculation(request);
			await calculation.trace;
			const historicalEligibility = await calculation.historicalEligibility({
				decisionId: 'branch-selected',
				placement: selected,
			});
			expect(historicalEligibility).toEqual([
				{
					date: '2024-01-03',
					reason: {
						code: 'unavailable',
						message: 'The selected entitlement is not available yet.',
					},
				},
			]);
			expect(receivedState?.balances[0]).toMatchObject({
				earned: true,
				sourceRuleId: 'producer',
			});
			expect(receivedOptions).toEqual({
				removeDate: '2024-01-02',
				compareOriginalState: true,
			});
			const analysis = await calculation.analyzeCounterfactual({
				decisionId: 'branch-selected',
				placement: selected,
			});
			expect(analysis.kind).toBe('Counterfactual');
			expect(receivedState?.placements.map((placement) => placement.date)).toEqual([
				'2024-01-01',
				'2024-01-02',
			]);
			expect(receivedState?.balances[0]?.remaining).toBe(3);
			expect(receivedState?.balances[0]).toMatchObject({
				availableFrom: '2024-01-02',
				earned: true,
				sourceRuleId: 'producer',
			});
			expect(receivedOptions).toEqual({
				removeDate: '2024-01-02',
				compareOriginalState: true,
			});
			await expect(
				calculation.analyzeCounterfactual({
					decisionId: 'self-parent',
					placement: selected,
				}),
			).rejects.toThrow('The selected trace decision is unavailable.');
		} finally {
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('does not inherit unrelated rule-invalid history into a trace decision', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-10' },
				balances: [balance('cp', 'cp', 1, '2024-01-31')],
				rules: [
					{
						id: 'early-window',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-02',
						endDate: '2024-01-04',
						placeDays: 1,
						placeType: 'cp',
					},
					{
						id: 'late-window',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-01-03',
						endDate: '2024-01-05',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			});
			const outcome = await calculation.outcome;
			const trace = await calculation.trace;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan' || !trace) return;
			const decision = trace.phases
				.flatMap((phase) => phase.decisions)
				.find((candidate) =>
					candidate.deltas.some((delta) => delta.kind === 'placement-added'),
				);
			const placement = decision?.deltas.find(
				(delta) => delta.kind === 'placement-added',
			)?.placement;
			expect(decision).toBeDefined();
			expect(placement).toBeDefined();
			if (!decision || !placement) return;

			const candidates = trace.phases.flatMap((phase) =>
				phase.decisions.flatMap((item) => item.candidates),
			);
			const decisionDates = new Set(
				decision.candidates.flatMap(
					(candidate) => candidate.dates ?? (candidate.date ? [candidate.date] : []),
				),
			);
			const unrelatedIneligible = candidates.find(
				(candidate) =>
					candidate.status === 'ineligible' &&
					candidate.reason?.code === 'rule-invalid' &&
					candidate.date &&
					!decisionDates.has(candidate.date),
			);
			expect(unrelatedIneligible).toBeDefined();
			if (!unrelatedIneligible?.date) return;

			const analysis = await calculation.analyzeCounterfactual({
				decisionId: decision.id,
				placement,
			});
			expect(analysis.kind).toBe('Counterfactual');
			if (analysis.kind !== 'Counterfactual') return;
			expect(
				analysis.results.find((result) => result.date === unrelatedIneligible.date)
					?.historicalStatus,
			).toBe('not-examined');
			expect(
				analysis.results.find((result) => result.date === '2024-01-06')?.historicalStatus,
			).toBe('ineligible');
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('reconstructs the returned plan from the original trace deltas', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-02-01' },
				balances: [balance('cp', 'cp', 4, '2024-01-31')],
				rules: [],
			});
			const outcome = await calculation.outcome;
			const trace = await calculation.trace;
			expect(outcome.kind).toBe('Plan');
			expect(trace?.status).toBe('ready');
			if (outcome.kind !== 'Plan' || !trace) return;

			const placements = new Map(
				trace.initialState.placements.map((placement) => [placement.date, placement]),
			);
			for (const delta of trace.phases.flatMap((phase) =>
				phase.decisions.flatMap((decision) => decision.deltas),
			)) {
				if (delta.previousPlacement) placements.delete(delta.previousPlacement.date);
				if (delta.placement) placements.set(delta.placement.date, delta.placement);
			}
			expect([...placements.values()].sort((a, b) => a.date.localeCompare(b.date))).toEqual(
				outcome.placements,
			);
			expect(trace.phases.map((phase) => phase.name)).toEqual(
				expect.arrayContaining([
					'obligations',
					'at-risk',
					'holiday-week-value',
					'non-working-day-gain',
					'longest-work-sequence',
					'short-sequence-deficit',
					'supporting-placements',
					'expiry',
					'dates',
				]),
			);
			expect(
				trace.phases
					.flatMap((phase) => phase.decisions)
					.flatMap((decision) => decision.candidates).length,
			).toBeGreaterThan(20);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('records loaded-plan pruning and full quality comparisons without truncation', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-04-01' },
				balances: [balance('cp', 'cp', 25, '2024-03-31')],
				rules: [],
			});
			expect((await calculation.outcome).kind).toBe('Plan');
			const trace = await calculation.trace;
			const decisions = trace?.phases.flatMap((phase) => phase.decisions) ?? [];
			const candidates = decisions.flatMap((decision) => decision.candidates);
			expect(
				candidates.some(
					(candidate) =>
						candidate.status === 'not-examined' &&
						candidate.reason?.code === 'loaded-plan-sampling',
				),
			).toBe(true);
			const comparison = candidates.find((candidate) => candidate.comparison)?.comparison;
			expect(comparison?.before.objectives.length).toBeGreaterThan(1);
			expect(comparison?.after.objectives.length).toBe(comparison?.before.objectives.length);
			expect(
				candidates.some((candidate) => candidate.comparison && candidate.sourceDate),
			).toBe(true);
			const chosenComparisons = decisions.flatMap((decision) =>
				decision.candidates
					.filter((candidate) => candidate.status === 'chosen' && candidate.comparison)
					.map((candidate) => ({ decision, candidate })),
			);
			expect(chosenComparisons.length).toBeGreaterThan(0);
			for (const { decision, candidate: chosen } of chosenComparisons) {
				expect(
					decision.deltas.some(
						(delta) =>
							(delta.kind === 'placement-moved' &&
								delta.toDate === chosen.date &&
								delta.balanceId === chosen.placement?.balanceId) ||
							(delta.kind === 'placement-added' &&
								delta.date === chosen.date &&
								delta.balanceId === chosen.placement?.balanceId) ||
							(delta.kind === 'placement-removed' && delta.date === chosen.date),
					),
				).toBe(true);
			}
			const phasesWithMultipleAcceptedMutations = trace?.phases.filter((phase) => {
				const acceptedMutations = phase.decisions.filter(
					(decision) =>
						decision.candidates.some(
							(candidate) => candidate.status === 'chosen' && candidate.comparison,
						) &&
						decision.deltas.some(
							(delta) =>
								delta.kind === 'placement-moved' ||
								delta.kind === 'placement-added' ||
								delta.kind === 'placement-removed' ||
								delta.kind === 'placement-updated',
						),
				);
				return acceptedMutations.length > 1;
			});
			expect(phasesWithMultipleAcceptedMutations?.length).toBeGreaterThan(0);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('records every eligible balance when a preference keeps the first assignment', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon: { start: '2024-01-01', end: '2024-01-10' },
				balances: [
					balance('later', 'cp', 1, '2026-01-01'),
					balance('earlier', 'cp', 1, '2025-01-01'),
				],
				rules: [
					{
						id: 'window',
						type: 'time_window',
						force: 'preference',
						startDate: '2024-01-02',
						endDate: '2024-01-02',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('Plan');
			if (outcome.kind !== 'Plan') return;
			expect(outcome.placements[0].balanceId).toBe('earlier');

			const trace = await calculation.trace;
			const candidates =
				trace?.phases
					.find((phase) => phase.name === 'preference:window')
					?.decisions.flatMap((decision) => decision.candidates)
					.filter((candidate) => candidate.date === '2024-01-02' && candidate.placement)
					.map((candidate) => ({
						balanceId: candidate.placement!.balanceId,
						status: candidate.status,
						reason: candidate.reason?.code,
					})) ?? [];
			expect(candidates.slice(0, 2)).toEqual([
				{ balanceId: 'earlier', status: 'chosen', reason: undefined },
				{ balanceId: 'later', status: 'not-examined', reason: 'first-compatible-balance' },
			]);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('offers no explanation trace for invalid input and explains conflicts', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const invalidCalculation = createPlanningCalculation({
				horizon: { start: '2025-01-01', end: '2024-01-01' },
				balances: [],
				rules: [],
			});
			expect((await invalidCalculation.outcome).kind).toBe('InvalidInput');
			expect(await invalidCalculation.explanation).toBeUndefined();
			expect(await invalidCalculation.trace).toBeUndefined();

			const conflictCalculation = createPlanningCalculation({
				horizon,
				balances: [balance('rtt', 'rtt', 1)],
				rules: [
					{
						id: 'cp-only',
						name: 'Paid leave only',
						type: 'time_window',
						force: 'obligation',
						startDate: '2024-04-01',
						endDate: '2024-04-05',
						placeDays: 1,
						placeType: 'cp',
					},
				],
			});
			expect((await conflictCalculation.outcome).kind).toBe('PlanningConflict');
			const explanation = await conflictCalculation.explanation;
			expect(explanation?.kind).toBe('ConflictExplanation');
			if (explanation?.kind === 'ConflictExplanation')
				expect(explanation.conflictingRules).toEqual([
					{ id: 'cp-only', label: 'Paid leave only' },
				]);
			const trace = await conflictCalculation.trace;
			expect(trace?.phases.some((phase) => phase.name === 'holiday-week-value')).toBe(false);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('marks interrupted and unexecuted phases when no incumbent exists', async () => {
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', undefined);
		try {
			const calculation = createPlanningCalculation({
				horizon,
				balances: [balance('cp', 'cp', 5)],
				rules: [],
				deadlineMs: 0,
			});
			const outcome = await calculation.outcome;
			expect(outcome.kind).toBe('PlanningIncomplete');
			const explanation = await calculation.explanation;
			expect(explanation?.kind).toBe('IncompleteExplanation');
			const trace = await calculation.trace;
			expect(trace?.phases.some((phase) => phase.status === 'interrupted')).toBe(true);
			expect(trace?.phases.some((phase) => phase.status === 'not-run')).toBe(true);
		} finally {
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('explains an incomplete incumbent without reusing the expired planning deadline', async () => {
		const core = await import('./leave-planner.core');
		let artifacts: import('./leave-planner.core').PlanningArtifacts | undefined;
		const outcome = core.calculatePlanningInternal(
			{
				horizon,
				balances: Array.from({ length: 12 }, (_, index) =>
					balance(`balance-${index}`, index % 2 ? 'rtt' : 'cp', 12),
				),
				rules: [],
				deadlineMs: 20,
			},
			undefined,
			(value) => (artifacts = value),
		);
		expect(outcome.kind).toBe('PlanningIncomplete');
		if (outcome.kind !== 'PlanningIncomplete') return;
		expect(outcome.incumbent).toBeDefined();
		expect(artifacts?.explanation?.kind).toBe('PlanExplanation');
		if (artifacts?.explanation?.kind !== 'PlanExplanation') return;
		expect(artifacts.explanation.incomplete?.reason.code).toBe('deadline');
		expect(artifacts.explanation.placements).toHaveLength(
			outcome.incumbent?.placements.length ?? 0,
		);
	});

	it('publishes the worker outcome before delayed explanation artifacts', async () => {
		const expected = isPlan(
			await runInNonBrowser({ horizon, balances: [balance('cp', 'cp', 1)], rules: [] }),
		);
		const trace = {
			status: 'ready' as const,
			initialState: {
				horizon,
				balances: [],
				placements: [],
				earnedActivations: [],
			},
			phases: [],
			completedStages: [],
		};
		class DelayedArtifactsWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(): void {
				queueMicrotask(() =>
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent),
				);
				setTimeout(
					() =>
						this.onmessage?.({
							data: { type: 'artifacts', artifacts: { trace } },
						} as MessageEvent),
					20,
				);
			}

			terminate(): void {}
		}
		vi.stubGlobal('Worker', DelayedArtifactsWorker);
		try {
			const calculation = createPlanningCalculation({
				horizon,
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			});
			let traceReady = false;
			void calculation.trace.then(() => (traceReady = true));
			expect((await calculation.outcome).kind).toBe('Plan');
			expect(traceReady).toBe(false);
			expect((await calculation.trace)?.status).toBe('ready');
		} finally {
			vi.unstubAllGlobals();
		}
	});

	it('delivers every streamed evaluation after ten seconds without delaying the outcome', async () => {
		const request = {
			horizon: { start: '2024-01-01', end: '2024-12-31' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		const expected = isPlan(await runInNonBrowser(request));
		const candidateCount = 768;
		const initialState: PlanningTraceState = {
			horizon: request.horizon,
			balances: [],
			placements: [],
			earnedActivations: [],
		};
		const operations: PlanningTraceUpdate['operations'][number][] = [
			{
				kind: 'phase',
				phase: { id: 'phase:1', name: 'search', completed: true, status: 'completed' },
			},
			{
				kind: 'decision',
				phaseId: 'phase:1',
				decision: { id: 'decision:1', action: 'choose', dates: ['2024-02-01'] },
			},
			...Array.from({ length: candidateCount }, (_, index) => ({
				kind: 'candidate' as const,
				phaseId: 'phase:1',
				decisionId: 'decision:1',
				index,
				mode: 'append' as const,
				candidate: { status: 'evaluated-rejected' as const, date: '2024-02-01' },
			})),
		];
		const trace = {
			status: 'ready' as const,
			initialState,
			completedStages: ['dates'],
		};
		class SlowTraceWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;
			terminated = false;

			postMessage(): void {
				queueMicrotask(() => {
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
					this.onmessage?.({
						data: {
							type: 'explanation',
							explanation: { kind: 'PlanExplanation', placements: [] },
							finalState: initialState,
						},
					} as MessageEvent);
				});
				setTimeout(() => {
					for (let offset = 0; offset < operations.length; offset += 64)
						this.onmessage?.({
							data: {
								type: 'trace-update',
								totalMs: 0,
								update: {
									initialState: offset === 0 ? initialState : undefined,
									operations: operations.slice(offset, offset + 64),
								},
							},
						} as MessageEvent);
					this.onmessage?.({
						data: {
							type: 'trace-status-index',
							statuses: new Map([['2024-02-01', 'evaluated-rejected']]),
							nonWorkingDates: [],
						},
					} as MessageEvent);
					this.onmessage?.({
						data: { type: 'artifacts-start', artifacts: {}, trace },
					} as MessageEvent);
					this.onmessage?.({ data: { type: 'artifacts-complete' } } as MessageEvent);
				}, 10_001);
			}

			terminate(): void {
				this.terminated = true;
			}
		}
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', SlowTraceWorker);
		vi.useFakeTimers({ toFake: ['setTimeout', 'clearTimeout', 'performance', 'Date'] });
		vi.setSystemTime(new Date('2024-01-01T12:00:00Z'));
		try {
			const calculation = createPlanningCalculation(request);
			let traceReady = false;
			const tracePromise = calculation.trace.then((value) => {
				traceReady = true;
				return value;
			});
			expect(await calculation.outcome).toEqual(expected);
			expect((await calculation.explanation)?.kind).toBe('PlanExplanation');
			expect(traceReady).toBe(false);
			const traceStarted = performance.now();
			await vi.advanceTimersByTimeAsync(10_001);
			await vi.runAllTimersAsync();
			const loadedTrace = await tracePromise;
			expect(performance.now() - traceStarted).toBeGreaterThanOrEqual(10_000);
			expect(loadedTrace?.phases[0].decisions[0].candidates).toHaveLength(candidateCount);
			expect(loadedTrace?.status).toBe('ready');
		} finally {
			vi.useRealTimers();
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('drains queued trace packets in batches of at most sixteen', async () => {
		const request = {
			horizon: { start: '2024-01-01', end: '2024-12-31' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		const expected = isPlan(await runInNonBrowser(request));
		const packetCount = 17;
		const initialState: PlanningTraceState = {
			horizon: request.horizon,
			balances: [],
			placements: [],
			earnedActivations: [],
		};
		const trace = {
			status: 'ready' as const,
			initialState,
			completedStages: ['dates'],
		};
		const updates = Array.from(
			{ length: packetCount },
			(_, index): PlanningTraceUpdate => ({
				initialState: index === 0 ? initialState : undefined,
				operations:
					index === 0
						? [
								{
									kind: 'phase',
									phase: {
										id: 'phase:1',
										name: 'search',
										completed: true,
										status: 'completed',
									},
								},
								{
									kind: 'decision',
									phaseId: 'phase:1',
									decision: {
										id: 'decision:1',
										action: 'choose',
										dates: ['2024-02-01'],
									},
								},
								{
									kind: 'candidate',
									phaseId: 'phase:1',
									decisionId: 'decision:1',
									index,
									mode: 'append',
									candidate: {
										status: 'evaluated-rejected',
										date: '2024-02-01',
									},
								},
							]
						: [
								{
									kind: 'candidate',
									phaseId: 'phase:1',
									decisionId: 'decision:1',
									index,
									mode: 'append',
									candidate: {
										status: 'evaluated-rejected',
										date: '2024-02-01',
									},
								},
							],
			}),
		);
		let performanceNowCalls = 0;
		let performanceNowCallsAtTermination = -1;
		let terminationCount = 0;
		let acknowledgementCount = 0;
		class BatchedTraceWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(message?: { type?: string }): void {
				if (message?.type === 'trace-ack') {
					acknowledgementCount++;
					return;
				}
				this.onmessage?.({ data: { type: 'result', outcome: expected } } as MessageEvent);
				this.onmessage?.({
					data: {
						type: 'explanation',
						explanation: { kind: 'PlanExplanation', placements: [] },
						finalState: initialState,
					},
				} as MessageEvent);
				this.onmessage?.({
					data: { type: 'artifacts-start', artifacts: {}, trace },
				} as MessageEvent);
				for (const update of updates)
					this.onmessage?.({
						data: { type: 'trace-update', totalMs: 0, update },
					} as MessageEvent);
				this.onmessage?.({
					data: { type: 'artifacts-complete', traceTransferMs: 0 },
				} as MessageEvent);
			}

			terminate(): void {
				terminationCount++;
				performanceNowCallsAtTermination = performanceNowCalls;
			}
		}
		const browserWindow = globalThis.window;
		const timeoutSpy = vi.spyOn(globalThis, 'setTimeout');
		vi.spyOn(performance, 'now').mockImplementation(() => {
			performanceNowCalls++;
			return 0;
		});
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', BatchedTraceWorker);
		try {
			const calculation = createPlanningCalculation(request);
			const loadedTrace = await calculation.trace;
			expect(loadedTrace?.phases[0].decisions[0].candidates).toHaveLength(packetCount);
			expect(timeoutSpy.mock.calls.filter(([, delay]) => delay === 0)).toHaveLength(2);
			expect(terminationCount).toBe(1);
			expect(performanceNowCallsAtTermination).toBe(2);
			expect(acknowledgementCount).toBe(0);
		} finally {
			vi.restoreAllMocks();
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('acknowledges marked trace packets only after applying them and waits for the tail', async () => {
		const request = {
			horizon: { start: '2024-01-01', end: '2024-12-31' },
			balances: [balance('cp', 'cp', 1)],
			rules: [],
		};
		const expected = isPlan(await runInNonBrowser(request));
		const initialState: PlanningTraceState = {
			horizon: request.horizon,
			balances: [],
			placements: [],
			earnedActivations: [],
		};
		const trace = {
			status: 'ready' as const,
			initialState,
			completedStages: ['dates'],
		};
		const phase = {
			kind: 'phase' as const,
			phase: { id: 'phase:1', name: 'search', completed: true, status: 'completed' as const },
		};
		const decision = {
			kind: 'decision' as const,
			phaseId: 'phase:1',
			decision: { id: 'decision:1', action: 'choose' as const, dates: ['2024-02-01'] },
		};
		const candidate = (index: number) => ({
			kind: 'candidate' as const,
			phaseId: 'phase:1',
			decisionId: 'decision:1',
			index,
			mode: 'append' as const,
			candidate: { status: 'evaluated-rejected' as const, date: '2024-02-01' },
		});
		const firstUpdate: PlanningTraceUpdate = {
			initialState,
			operations: [phase, decision, candidate(0)],
		};
		const tailUpdate: PlanningTraceUpdate = { operations: [candidate(1)] };
		let acknowledgePackets = 0;
		let tailSent = false;
		let resolveFirstAcknowledgement!: () => void;
		const firstAcknowledgement = new Promise<void>(
			(resolve) => (resolveFirstAcknowledgement = resolve),
		);
		class AcknowledgedTraceWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(message: { type?: string; count?: number }): void {
				if (message.type === 'trace-ack') {
					acknowledgePackets += message.count ?? 0;
					if (acknowledgePackets === 1) {
						tailSent = true;
						queueMicrotask(() =>
							this.onmessage?.({
								data: {
									type: 'trace-update',
									totalMs: 0,
									update: tailUpdate,
									acknowledge: true,
								},
							} as MessageEvent),
						);
						resolveFirstAcknowledgement();
					} else if (acknowledgePackets === 2)
						queueMicrotask(() =>
							this.onmessage?.({
								data: { type: 'artifacts-complete', traceTransferMs: 0 },
							} as MessageEvent),
						);
					return;
				}
				this.onmessage?.({ data: { type: 'result', outcome: expected } } as MessageEvent);
				this.onmessage?.({
					data: {
						type: 'explanation',
						explanation: { kind: 'PlanExplanation', placements: [] },
						finalState: initialState,
					},
				} as MessageEvent);
				this.onmessage?.({
					data: { type: 'artifacts-start', artifacts: {}, trace },
				} as MessageEvent);
				this.onmessage?.({
					data: {
						type: 'trace-update',
						totalMs: 0,
						update: firstUpdate,
						acknowledge: true,
					},
				} as MessageEvent);
			}

			terminate(): void {}
		}
		const browserWindow = globalThis.window;
		vi.stubGlobal('window', {});
		vi.stubGlobal('Worker', AcknowledgedTraceWorker);
		try {
			const calculation = createPlanningCalculation(request);
			let traceReady = false;
			const tracePromise = calculation.trace.then((result) => {
				traceReady = true;
				return result;
			});
			await calculation.outcome;
			expect(acknowledgePackets).toBe(0);
			expect(traceReady).toBe(false);
			await firstAcknowledgement;
			expect(tailSent).toBe(true);
			expect(traceReady).toBe(false);
			const loadedTrace = await tracePromise;
			expect(acknowledgePackets).toBe(2);
			expect(loadedTrace?.phases[0].decisions[0].candidates).toHaveLength(2);
		} finally {
			vi.unstubAllGlobals();
			vi.stubGlobal('window', browserWindow);
		}
	});

	it('keeps a valid outcome when trace delivery fails afterward', async () => {
		const expected = isPlan(
			await runInNonBrowser({ horizon, balances: [balance('cp', 'cp', 1)], rules: [] }),
		);
		class FailingArtifactsWorker {
			onmessage: ((event: MessageEvent) => void) | null = null;
			onerror: (() => void) | null = null;

			postMessage(): void {
				queueMicrotask(() => {
					this.onmessage?.({
						data: { type: 'result', outcome: expected },
					} as MessageEvent);
					queueMicrotask(() => this.onerror?.());
				});
			}

			terminate(): void {}
		}
		vi.stubGlobal('Worker', FailingArtifactsWorker);
		try {
			const calculation = createPlanningCalculation({
				horizon,
				balances: [balance('cp', 'cp', 1)],
				rules: [],
			});
			expect(await calculation.outcome).toEqual(expected);
			expect((await calculation.trace)?.status).toBe('failed');
			expect((await calculation.explanationError)?.code).toBe('worker-error');
		} finally {
			vi.unstubAllGlobals();
		}
	});
});