> ## Documentation Index
> Fetch the complete documentation index at: https://developers.haia.finance/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Local-first Operation Receipts for agentic payments.

**Haia Trace** passively records the lifecycle of a payment operation and
assembles a single verdict — what completed, what's missing, and which faults
were observed — entirely on your machine, with no registration.

The one artifact is the **Operation Receipt**. It is:

<CardGroup cols={3}>
  <Card title="Not a log" icon="list">
    A log shows events. A Receipt interprets them — comparing the operation's
    expected flow against what was actually observed and stating a verdict.
  </Card>

  <Card title="Not a merchant receipt" icon="receipt">
    A merchant issues its own receipt. A Trace Receipt is built from *your*
    observations, so it holds up in a dispute with that merchant.
  </Card>

  <Card title="Not a dashboard" icon="chart-line">
    Not trends across many operations — the full, evidence-backed account of
    one.
  </Card>
</CardGroup>

## How it fits together

```text theme={null}
  your x402 app                         the Trace toolchain
┌─────────────────────┐   records   ┌──────────────────────────────────┐
│ x402 client/server  │──hooks─────▶│ @usehaia/trace-x402  (adapter)   │
│ facilitator / MCP   │             │        │  Event Contract          │
└─────────────────────┘             │        ▼                         │
                                    │ .trace/events/<run>.ndjson       │
                                    │        │                         │
                                    │        ▼                         │
                                    │ @usehaia/trace-core  (assembler) │
                                    │        │  Receipt                 │
                                    │        ▼                         │
                                    │ haia-trace  build · sample       │
                                    └──────────────────────────────────┘
```

Events are the source of truth; a Receipt is derived and reproducible — the same
NDJSON always assembles to the same Receipt.

## The packages

<CardGroup cols={3}>
  <Card title="@usehaia/trace-cli" icon="terminal" href="/cli/overview">
    The `haia-trace` command — assembles and renders receipts.
  </Card>

  <Card title="@usehaia/trace-x402" icon="plug" href="/sdk/x402">
    Capture adapter for the x402 payment SDK.
  </Card>

  <Card title="@usehaia/trace-core" icon="cube" href="/sdk/core">
    Contracts and the deterministic receipt assembler.
  </Card>
</CardGroup>

<Note>
  Haia Trace is pre-1.0. The `trace-core` contracts and assembler and the
  `haia-trace` CLI (`sample`, `build`, `templates`) are in place. The
  `trace-x402` adapter records the x402 lifecycle hooks passively today;
  normalizing those firings into `.trace/events` and payload redaction are on
  the roadmap. See [Connect x402](/sdk/x402).
</Note>

Ready to see a Receipt? Head to the [Quickstart](/quickstart).