Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2025	Apr. 30, 2024
Deferred tax assets
Accrued payroll	$ 7,483	$ 5,542
Other accruals & reserves	3,423	5,933
Operating lease liability	13,696	13,433
Deferred revenue	1,354	1,643
Net operating losses	179,554	141,157
R&D tax credit	20,396	15,001
Stock based compensation	15,710	13,263
Capitalized R&D expenditure	93,759	72,140
Other	362	626
Gross deferred tax assets	335,737	268,738
Valuation allowance	(320,939)	(252,682)
Total deferred tax assets	14,798	16,056
Deferred tax liabilities
Prepaid expenses	(1,774)	(1,986)
Depreciation	(8,635)	(9,808)
Operating lease right-of-use assets	(4,389)	(4,262)
Total deferred tax liabilities	(14,798)	(16,056)
Net deferred tax assets (liabilities)	$ 0	$ 0