Prepayments and other current assets - Schedule of movements in the allowance of prepayments and other current assets for credit losses (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Prepayments and other current assets, net
Balance as of January 1	¥ 18,102	¥ 154
Write-off	(6,862)
Amounts charged to expenses	520	17,948
Balance as of December 31	¥ 11,760	¥ 18,102

Amount of direct write-downs of accounts receivable charged against the allowance.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration