> ## Documentation Index
> Fetch the complete documentation index at: https://whalescorp.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# What Is Already Correct

* Append-only `fee_ledger` with status state machine
* Unique invoice per period (`invoices_instance_period` index)
* Secure session (passkey re-auth) for all financial mutations
* Non-blocking fee collection — cheques work even if fees fail
* Atomic invoice number generation via JSONB sequence
* Multi-tenant isolation — all financial queries include `instance_id`
* CSV export for external accounting
* On-chain collection with atomic lock (`FOR UPDATE SKIP LOCKED`)


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