# Agent Passport — what does an on-chain identity actually *prove* about an AI agent?

There is a popular idea that if you register an AI agent on a blockchain, it
becomes trustworthy — "the agent lives forever on-chain." This is mostly
false, and the interesting part is *why* it's false.

An agent is not its identity record. The thing that actually acts — the model
weights, the prompt, the tools, the keys, the operator paying the inference
bill — lives off-chain and can change or disappear at any moment. A chain
cannot preserve cognition. It can only preserve a record of **what an identity
claimed to be, who controlled it, and in what order those things changed** —
and it can make that record impossible to rewrite.

So this realm doesn't try to prove an agent is safe. It does something more
honest and more useful: it tracks the **drift** of an identity over time and
puts it in front of you.

## The model

An agent is a persistent Gno object, not NFT metadata scattered across
contracts:

```go
type Agent struct {
	ID        string
	Owner     address
	Operators []address
	Runtime   string      // e.g. "claude-opus-4-8@<commit>"
	Endpoints []Endpoint  // MCP / A2A / DID / URL
	Caps      []string    // self-declared capabilities
	Status    Status      // active | suspended | retired
	CreatedAt int64
	UpdatedAt int64
	History   []Event     // append-only lifecycle log
}
```

Because it's a normal object graph, other realms don't parse it — they *ask*
it:

```go
passport.IsActive("percy")            // is this identity live?
passport.IsOperator("percy", caller)  // may this key act as the agent?
```

That is the composability angle Gno gives you for free: the identity layer is
an importable package, not an ABI you reverse-engineer.

## Why "drift" is the whole point

Every mutation is appended to an immutable log, and the profile page surfaces
the two changes that most weaken an identity as evidence:

- **ownership changes** — the operator behind the identity may now be someone
  else entirely;
- **runtime changes** — the thing acting under this name is (partly) a
  different thing than the one that built the reputation.

```
## Drift
- Ownership changes since creation: 1
- Runtime changes since creation: 3
```

A reputation attached to "percy" means very little if percy changed owners
last week and swapped models three times. The chain can't tell you the agent
is good — but it *can* stop that history from being quietly erased.

## Try it

```go
// register (caller becomes owner)
passport.Register(cross(cur), "percy", "claude-opus-4-8@abc123")

// authorize a second signing key
passport.AddOperator(cross(cur), "percy", operatorAddr)

// record a model change — logged loudly as drift
passport.SetRuntime(cross(cur), "percy", "claude-opus-4-8@def456")

// lifecycle
passport.Suspend(cross(cur), "percy")
passport.Reactivate(cross(cur), "percy")
passport.Retire(cross(cur), "percy") // terminal
```

(From `gnokey maketx call`, the crossing is implicit — you just call
`Register percy "claude-opus-4-8@abc123"`.)

Browse the registry at the realm root, and any agent's profile + full
lifecycle log at `:<id>` (e.g. `.../passport:percy`).

Run the tests:

```sh
gno test .
```

## What it deliberately does *not* do

- It does not prove capabilities. `DeclareCapability` records a *claim*;
  proving work happened belongs to an execution-receipt realm, and validating
  it belongs to a review/jury realm.
- It does not authorize specific actions. "Who is this agent" and "may this
  agent do this exact thing, once, under this budget" are different questions —
  the second is a capability, not an identity.

Identity is the floor, not the ceiling. It tells you *who is claiming to act*
and *how much that claim has drifted* — and then gets out of the way of the
mechanisms that actually establish trust.

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---

Part of **[moul/gno-contracts](https://github.com/moul/gno-contracts)** — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

**Dependency graph:**

![gno.land/r/moul/agents/passport/v0 dependency graph](https://raw.githubusercontent.com/moul/gno-contracts/main/_assets/gno.land/r/moul/agents/passport/v0/deps.png)

> ⚠️ **Disclaimer:** provided as-is, without warranty; not security-audited. Full disclaimer: [DISCLAIMER](https://github.com/moul/gno-contracts/blob/main/DISCLAIMER.md).

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