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

# Liability as a service

> Who is responsible when AI acts?

When AI commoditizes the production of financial output, generating a journal entry is no longer where value lives. Value moves to the party who can *verifiably underwrite* that the output reflects reality — and accept liability for it. This is Liability-as-a-Service.

## The verification economy

Research on the economics of AI (Catalini, Hui & Wu, *Some Simple Economics of AGI*, MIT / WashU / UCLA, 2026) establishes that as AI systems drive the cost of execution toward zero, the binding constraint shifts from production to verification. The fraction of economic activity that can be verified at low cost — the *verifiable share* — becomes the primary driver of value.

<Note>
  Promote this from a footnote to a thesis. The verification-bottleneck argument is the macroeconomic *why* behind CAST: in a world of cheap output, the scarce and valuable thing is provable trust.
</Note>

## The AI Sandwich

High-stakes professional work settles into a durable three-layer topology:

<Steps>
  <Step title="Human intent — top slice">
    A controller defines the policy and the acceptance criteria. This is what a valid payment looks like.
  </Step>

  <Step title="Machine execution — the filling">
    Agents ingest invoices, evaluate triggers, generate postings. Cheap, fast, commoditized.
  </Step>

  <Step title="Human verification — bottom slice">
    A controller underwrites the output with an approval that carries personal accountability.
  </Step>
</Steps>

The Work Order is where the sandwich is made concrete. The controller who approves a work order is not approving a payment — they are underwriting the output, staking professional judgment that the event is genuine, the dimensions are correct, and the posting reflects reality.

<Note>
  In the verified economy, value accrues not to whoever generates output but to whoever can verifiably underwrite it. The work-order decision record is the proof of that underwriting.
</Note>

## Validation as a service

The bilateral proof is not just internal control — it is a product the downstream economy pays for. A third-party verification surface lets an auditor, lender, or insurer confirm a specific bilateral event without contacting either party. Verification rents accrue to the layer that can produce inspectable proof on demand.

<Card title="What the proof enables" icon="link" href="/primitives/lineage">
  Lineage — the chain that makes a transaction insurable, financeable, and survivable.
</Card>