Schedule of retention receivables, net (Details)	Sep. 30, 2025 USD ($)	Sep. 30, 2025 HKD ($)	Sep. 30, 2024 HKD ($)
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Retention receivables		$ 4,149,411	$ 3,879,245
Less: allowance for credit loss		(420,000)	(510,000)
Retention receivables, net	$ 479,174	$ 3,729,411	$ 3,369,245

Amount, before allowance, of receivables classified as other, due within one year or the operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480657/210-10-S50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Name:	us-gaap_OtherReceivablesGrossCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant