Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Operating activities
Net loss	$ (46,278)	$ (49,211)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	5,082	5,923
Amortization of right-of-use lease assets	1,416	2,032
Depreciation	2,086	1,667
Long-lived asset impairment	0	1,900
Accretion of debt issuance costs	79	71
Amortization of premium (accretion of discount) on short-term investments	(993)	1,060
Changes in operating assets and liabilities:
Accounts receivable	125	881
Inventory, net	(1,590)	468
Prepaid expenses and other current assets	1,355	(337)
Other noncurrent assets	72	(71)
Accounts payable	(155)	(1,494)
Accrued expenses	(1,861)	(470)
Other current liabilities	(147)	109
Lease liabilities	(952)	(521)
Other noncurrent liabilities	20	61
Net cash used in operating activities	(41,741)	(37,932)
Investing activities
Purchases of short-term investments	(37,853)	(95,249)
Maturities of shot-term investments	93,253	114,096
Sales of short-term investments	169	19,480
Purchases of property and equipment	(26)	(468)
Net cash provided (used) by investing activities	55,543	37,859
Financing activities
Proceeds from issuance of common stock under employee stock purchase plan	80	624
Proceeds from issuance of common stock under equity incentive plans	0	13
Repurchases of common stock under equity incentive plans	0	(13)
Net cash provided by financing activities	80	624
Net increase in cash and cash equivalents and restricted cash	13,882	551
Cash and cash equivalents and restricted cash, beginning of year	16,833	75,977
Cash and cash equivalents and restricted cash, end of year	30,715	76,528
Supplemental disclosure for cash activities
Interest paid	494	530
Supplemental disclosure for non-cash activities
Inventory transferred to property and equipment	1,643	3,752
Purchases of inventory included in accounts payable	209	319
Purchases of inventory included in accrued expenses	0	34
Vesting of common stock issued for early exercise of stock options	46	209
Purchase of property and equipment included in accounts payable	$ 0	$ 50