Summary of significant accounting policies - Impairment for long-lived assets (Details) - USD ($)	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Summary of significant accounting policies
Impairment loss of long-lived assets	$ 0	$ 0	$ 6,472,266

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration