> ## Documentation Index
> Fetch the complete documentation index at: https://docs.algovoi.co.uk/llms.txt
> Use this file to discover all available pages before exploring further.

# Retention App

> Signed, offline verifiable payment receipt retention: auto maintained per issuer hash linked chains and Falcon-1024 signed evidence exports for auditors.

<Note>
  **Included in the [Verifiable Compliance Suite](/verifiable-compliance-suite).** One commercial licence installs this component together with the whole compliance estate, self-hosted and air-gap capable. It is also available as a standalone licence.
</Note>

Payment settlement proves money moved. It does not prove what the agent did, or that the record of
what it did has been preserved intact. Regulated retention rules (MiCA Article 80, DORA Article 14,
AMLR Article 56) ask you to keep an unbroken, demonstrable record of payment activity, and to be able
to hand that record to a regulator who can check it without trusting you.

The **Retention App** is the stateful service that does this. You hand it a payment-receipt hash; it
maintains the chain.

<Note>
  Built on the open [Retention Chain substrate](/retention-chain-substrate) (the Apache-2.0 reference
  primitive). The Retention App is the commercial product around it: state, signing, export, and the
  Compliance Command Center bolt-in.
</Note>

## You supply a hash, it maintains the chain

Post a receipt hash for an issuer and the app does the bookkeeping for you. It derives the sequence
position, links the entry to the previous one, and computes the `retention_chain_ref`. Each issuer
gets its own strictly append-only chain. Duplicate receipts are rejected and gaps cannot occur,
because the sequence and the previous link are derived from the chain head, not from the caller.

## Trust does not live in the database

Every entry is content-addressed, and every exported pack is signed. Verification recomputes the
chain from the entries themselves, so a database swap, a migration, or silent corruption cannot forge
integrity. The store is an index, not the system of record.

## Verify-it-yourself evidence export

Export an issuer's chain as a single Falcon-1024 signed evidence pack. The pack bundles a
redistributable verifier; the recipient runs it and gets a clear pass or fail, **offline**:

* **No AlgoVoi software, service, account, or network** is involved in their verification.
* The verifier recomputes every signature, every chain link, and every `retention_chain_ref`.
* Tampering with any entry makes verification fail.

## Bolts into the Compliance Command Center

The Retention App is a first-class bolt-in to the [Compliance Command Center](/compliance-command-center):

* **Live service health.** It self-registers on boot, so the console shows its health alongside the
  rest of your estate.
* **Signed evidence posture.** Its exported packs are exactly what the Command Center ingests and
  re-verifies offline, so retention appears in your one proven posture, not as a vendor assertion.

## Deployment

A self-hosted FastAPI service. DSN-backed storage, SQLite by default or PostgreSQL for a managed
deployment. Self-hosted on your infrastructure, air-gap capable.

<Note>
  An add-on priced product. Pairs with the Compliance Command Center, which ingests and re-verifies
  the signed retention evidence it exports.
</Note>