ADI
ADI Blog System architecture 1 min read

Separating A2A, trust, and AP2

The key architectural principle is separating the layers. A2A is communication. Trust is governance. AP2 is payment behavior.

A2A requires an AgentCard, interfaces, and security declarations, not a generic "A2A certificate."

Trust is added when identity, delegation, revocation, or external governance matter.

AP2 appears only when an agent participates in real payment and mandate flows.

What A2A actually is

A2A standardizes discovery, messages, tasks, and optional extensions between agents. It defines how an agent is found and how other agents speak to it.

A2A does not automatically solve identity binding, organization governance, or payment mandates. Those concerns live outside the core protocol or inside extensions.

What the trust layer adds

Binding the agent to an operator, person, or organization

Verifiable credentials, certificate status, and revocation

Delegation and policy rules

Blocklists, audit trails, and transaction control points

What AP2 adds

Roles such as merchant, shopper, credentials provider, and payment processor

Mandates such as CartMandate, IntentMandate, and PaymentMandate

Tokenized payment methods and payment proofs

A standard vocabulary for agent payments

The practical decision rule

A2A only: for internal or simple service agents with low accountability demands

A2A plus trust: for external, governed, or compliance-relevant agents

A2A plus trust plus AP2: for commerce, wallet, and payment agents

CONTINUE READING

More articles from the technical reading layer.

OPEN AGENT TRUST Agent interoperability

How external agents verify an ADI merchant agent

A buyer agent does not have to live inside ADI to trust an ADI merchant agent. It needs public discovery, a resolvable agent identity, signed credentials, and a clear payment mandate path. This article shows how those pieces fit together.

A2A discovery makes the merchant agent reachable.

ADI trust discovery makes the merchant agent accountable.

MERCHANT TRUST Agent commerce

How the merchant trust catalog works

A merchant agent can sell from the merchant shop, but ADI needs an independent trust reference for what that agent is allowed to sell. The merchant catalog in ADI is that reference: a canonical product whitelist used to validate agent commerce before money moves.

The shop catalog runs the business.

The ADI catalog proves what the merchant approved.

AP2 VALIDATION Agent commerce

How ADI validates what a merchant agent sells

A merchant agent can describe an offer, but ADI should not pay from description alone. ADI validates the AP2 mandates, the merchant organization, the product SKU, the trusted catalog entry, the buyer wallet, and the virtual-card policy before the transaction becomes authorized.

Conversation creates intent.

AP2 creates structured mandates.

INTEGRATIONS Agent commerce

Why shop integrations are trust inputs, not the trust layer

Shopify, WooCommerce, CSV, custom APIs, and marketplace connectors help ADI import merchant product state. They are not the trust layer by themselves. The trust layer begins when ADI normalizes that product state, binds it to a merchant organization, and uses it in mandate and payment checks.

Integration is ingestion.

Catalog governance is trust.

INTEGRATION MODES Agent integration

Three ways to connect an external agent to the ADI trust layer

An external agent does not need to run inside ADI to be governed by ADI. The practical question is how the relying system authenticates that agent and when it asks ADI for trust, delegation, and certificate state.

Standard mode: API key or agent token plus online trust lookup

Enterprise mode: OIDC plus trust lookup

TRUST FOUNDATIONS Agent trust

Why agents need a trust layer

An API token only tells you whether a request is authenticated. A trust layer tells you which agent is acting, on whose behalf, which proofs are valid, and whether that agent can be stopped.

When OAuth stops being enough

Which questions a trust layer must answer

PRODUCT ADI stack

How ADI works as an agent trust stack

ADI is not a single interface. It is an operational layer that connects discovery, identity, trust, and payment flows for agentic systems.

The platform’s four layers

Where A2A, MCP, and AP2 meet

A2A EXPLAINED A2A fundamentals

What A2A is and what it is not

A2A gives agents a shared way to describe themselves, exchange messages, and execute tasks. It does not automatically solve identity binding, delegated authority, auditability, or payment control.

A2A standardizes discovery, messages, tasks, and declared security capabilities.

A2A does not by itself answer who the agent represents or what it is permitted to do.

AP2 FOUNDATIONS AP2 payments

What AP2 solves for agent commerce

AP2 gives agent commerce a structured model for intent, cart, payment authorization, and receipts. Without that model, every agent-payment integration invents its own fragile semantics.

AP2 introduces a common vocabulary for agent payment flows.

Mandates separate scope, intent, and final payment authorization.

TRUST FOUNDATIONS Agent trust

What agent trust actually means

Agent trust is not a brand claim. It is the operational ability to prove who an agent is, on whose behalf it acts, what it is allowed to do, and how that authority can be revoked or audited.

Trust begins where authentication alone stops.

A real trust layer must support revocation, inspection, and evidence.

PRODUCT EXPLAINER ADI stack

What ADI does in an agent stack

ADI is the trust and control layer that sits between agent interoperability and real business action. It helps organizations let agents act without treating those agents like ungoverned black boxes.

ADI is where governance enters the agent stack.

The platform connects external agents, enterprise controls, and transaction policies.

SIGNATURES AND SEALS Trust services

Human signatures vs organization eSeals

A human signature proves the will or approval of a natural person. An organization eSeal proves that a trust object was issued or sealed by a legal entity. In enterprise agent systems, those are different jobs and they should not be collapsed into one.

Human signatures answer: who personally approved this?

Organization eSeals answer: which legal entity issued or stands behind this artifact?