How Lerian STA works

How Lerian STA works: outbound submission and inbound file discovery to BACEN, protocol state machine, SHA-256 integrity, retry budgets, and operator actions.

Lerian STA moves files in two directions. Each exchange is one transfer — a single file that moves between the institution and BACEN. A protocol number tracks the transfer through BACEN’s protocol lifecycle. Each end verifies the SHA-256.

Outbound submission

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The institution, or an upstream Lerian product, hands Lerian STA a file for BACEN. Lerian STA then obtains a protocol number from BACEN. It uploads the file’s bytes. BACEN validates the bytes against the declared SHA-256.

The transfer advances through BACEN’s lifecycle:

State	Meaning
Protocol generated	BACEN has assigned the protocol number.
Transmitting	Lerian STA is uploading the bytes.
Integrity check	BACEN is validating the declared SHA-256.
Received	BACEN has received the file.
Delivered	BACEN has delivered the file to its destination.
In processing	BACEN is processing the file.
Accepted	BACEN has accepted the file — a terminal success.
Rejected / Inconsistent	BACEN has refused the file — a terminal failure.

Upload retries within a bounded budget. Once Lerian STA exhausts the retry budget, it cancels the transfer. Each protocol also carries a bounded wall-clock TTL — 44 hours by default. Lerian STA must finish the upload before BACEN expires the protocol.

Inbound discovery and download

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Lerian STA polls BACEN for available files, per active tenant, on a configured cadence.

For each file, Lerian STA matches the file’s BACEN system code against the tenant’s inbound source configurations. It then downloads the bytes. It verifies the bytes against BACEN’s reported SHA-256. It stores the file durably in object storage.

A hash mismatch or a download failure retries within a bounded budget. Once Lerian STA exhausts the budget, it quarantines the transfer to a terminal failure — inconsistent or canceled. It does not deliver the file to its source product.

Operator actions

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An operator can act only where the transfer’s state and configuration permit it:

• Cancel only when the canonical state machine permits a transition to Canceled; it is not allowed from every non-terminal state.
• Retry an outbound transfer only when it is non-terminal, has upload budget remaining, and its protocol TTL has not expired.
• Mark urgent only for an inbound transfer in AvailableForDownload whose source configuration has urgency enabled; it fails closed otherwise.

Lerian STA also cancels a transfer when its BACEN protocol expires.