feat(benchmark): enhance benchmark documentation and add emulated run details

fix(benchmark): update deterministic checks and improve measurement accuracy

fix(service): refine candidate recording and enhance balance assignment logic

test(service): add test for balance recording with preference assignment

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

@@ -1660,6 +1660,53 @@ describe('planning calculation context', () => {
 		}
 	});
 
+	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: 'evaluated-rejected', 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);