Module 3: Decision
Steps 2 and 4 in the Bundesbank flow. Layer: decision-making. Actors: the AI agent, the merchant and the gateway.
In the traditional architecture nobody drew a decision-making layer, because the decisions were a person's. The Deutsche Bundesbank's flow has two points where the agent decides on the customer's behalf, and its chart gives that activity a layer of its own. This module is about those two decisions: what is chosen, what steers the choice, and what has to happen to a probabilistic choice before a payment system will act on it.
By the end of this module you will be able to:
- State what is decided at step 2 and step 4, and what information the agent decides from
- Explain why the Bundesbank says no payment-specific standards exist at this layer, and what defines the agent's options instead
- Describe the ways an agent's decision can be wrong, in the Bundesbank's terms, and the two it treats as systemic
- Explain the governance rule that probabilistic decisions must become deterministic processes before execution, and name a runtime design that does it
- Identify who can steer an agent's choice of merchant and payment instrument, and through what
Step 2: which product, from whom
Product selection is the first decision. The customer's purchase order from step 1 said what they want. The agent searches, compares and selects a specific item from a specific merchant. In the Bundesbank's full-autonomy case it does this with no further input from the person.
What does it decide from? From whatever it can reach (Module 2) and whatever it has been told to prefer. The mandate's scope limits which merchants and categories are in play. The purchase order supplies the goal. Everything else is the agent's judgment: price, availability, delivery, the customer's history, and anything the merchant has put in front of it.
That last item is the one to hold on to. The Bundesbank observes that merchants will need machine-readable catalogs and agent-compatible interfaces, and that they could also guide the use of specific payment instruments and influence agent preferences through attractive conditions. A merchant who understands step 2 is not just listing products for an agent. It is competing for the agent's choice.
Step 4: which way to pay
After the merchant delegates checkout to its gateway (step 3), the gateway offers the agent the available payment methods and the agent selects one. The chart draws this as a two-way exchange between gateway and agent, colored decision-making.
The Bundesbank is specific about what an agent optimizes for here. It can select the means of payment so as to take advantage of discounts and price reductions, and to maximize loyalty points or cashback. In the cross-border case it can compare providers and instruments and pick the rail, including the currency conversion route. In combination with instant payments, the Bundesbank expects agents to identify cheaper and faster rails and to systematically prioritize cost-efficient means of payment over means with wider margins.
The mandate constrains this. Module 1's limits field names the permitted instruments and rails, and the order of preference. Within those, the agent chooses. A household that wrote "prefer instant credit transfer over card where accepted" has made the step 4 decision in advance for the common case and left the agent to handle the rest.
A layer with no standards
The Bundesbank's description of the decision-making layer is short and worth quoting in substance. No payment-specific standards exist at present. Instead, the architecture of the agentic framework determines what actions an agent can perform and so defines what actions are passed to the downstream layers.
That means the thing deciding how your payment is chosen is not a payments standard anyone can read. It is the framework the agent runs in, the model behind it, and the prompt and tools it was given. The chart's protocol box for this layer says only "agentic frameworks". The actors are technology corporations and AI providers.
In the traditional architecture, decision-making was never a technical layer. The agent makes it one, and there is no standard for it.
For a payments person that is an unusual position to be in. Every other layer of the flow has a specification you can test against. This one has a model.
Why it is still a payment decision
It is tempting to treat steps 2 and 4 as shopping and leave them to the commerce people. The Bundesbank's framing resists that. The choice of payment instrument at step 4 decides which rail carries the money, which fees are paid, who earns them, and which protections apply. An agent that systematically picks the cheapest rail changes the revenue of every intermediary on the dearer one. Section 4 of the report says this plainly: existing sources of revenue and business models would come under pressure, and agentic payments could tend to avoid existing, currently profitable payment networks.
So the decision layer is where the economics of the whole flow are set, by software, under a mandate, with no standard. The next lesson asks what that software is and why its decisions need to be made deterministic before anything is paid.
Next lesson: probabilistic decisions in a deterministic system.