Significant Accounting Policies - Narrative (Details) - USD ($)	3 Months Ended						9 Months Ended
	Jan. 31, 2024	Oct. 31, 2023	Jul. 31, 2023	Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Jan. 31, 2024	Jan. 31, 2023	Apr. 30, 2023
Accounting Policies [Abstract]
Cash equivalents	$ 2,900,000						$ 2,900,000		$ 0
Cash above US insurance limit	3,300,000						3,300,000		8,700,000
Net loss	(2,530,000)	$ (2,071,000)	$ (2,566,000)	$ (2,439,000)	$ (16,000)	$ (319,000)	(7,167,000)	$ (2,774,000)
Net cash provided by (used in) operating activities							(4,321,000)	4,664,000
Accumulated deficit	(84,484,000)						(84,484,000)		(77,317,000)
Cash and cash equivalents	4,468,000						4,468,000		10,118,000
Unrecognized tax benefits	181,000						181,000		181,000
Income tax penalties and interest expense	0			0			0	0
Unrecognized tax benefits anticipated during the next 12 months	0						0
Provision for income taxes	11,000			$ 17,000			49,000	$ 48,000
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0						0		0
Assets, fair value									0
Nonrecurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	$ 0						$ 0		0
Assets, fair value									$ 0