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

# Introduction

> Drop-in mirrors for Stripe, Resend, Twilio, and the rest of your application infrastructure.

Your code talks to ten, twenty, thirty third-party services. Payments, email, SMS, auth, commerce, inference. Every one of them is a surface for bugs — bugs that only surface when a real webhook fires, a real state machine transitions, or a real error payload arrives.

Testing that code is the problem Mirra solves.

## What Mirra is

Mirra is a runtime that provides **faithful, stateful mirrors** of the third-party APIs your application depends on. Point your code at a Mirra URL instead of the real vendor and it behaves identically — same webhook signatures, same state machine transitions, same error payloads, same idempotency enforcement — but without the real-world side effects.

No money charged. No messages sent. No emails delivered. No accounts polluted.

```bash theme={null}
$ npx @mirrahq/cli up

→ detected: stripe, resend, twilio
→ provisioning mirrors…
✓ stripe    → https://stripe-a7k2.mirra.run
✓ resend    → https://resend-a7k2.mirra.run
✓ twilio    → https://twilio-a7k2.mirra.run

session ses_a7k2 ready in 1.8s
```

Your Stripe SDK client, pointed at `stripe-a7k2.mirra.run`, sees a real running implementation of Stripe's API. Create a customer — they stay created. Cancel a subscription — webhooks fire on the correct schedule, signed with HMAC-SHA256 using the exact scheme Stripe uses.

## What makes a mirror different from a mock

A mock returns a hardcoded response. A mirror runs a real process with real state.

<Columns cols={2}>
  <Card title="Stateful" icon="database">
    Every session gets its own SQLite database. Records you create persist. State machines transition on the right schedule. Nothing is hardcoded.
  </Card>

  <Card title="Faithful" icon="shield-check">
    Vendor-correct webhook signatures. Vendor-correct error payloads. Vendor-correct rate limits. Byte-for-byte parity, verified weekly against the live API.
  </Card>

  <Card title="Isolated" icon="boxes-stacked">
    A thousand parallel CI runs don't see each other. No shared-staging collisions. Teardown is instant.
  </Card>

  <Card title="Drop-in" icon="plug">
    A TLS proxy routes `api.stripe.com` to the mirror transparently. Your existing SDK clients work without URL changes.
  </Card>
</Columns>

## Three ways to use Mirra

One runtime, three execution modes:

<Steps>
  <Step title="mirra up — for local development and staging">
    Provision mirror URLs and keep them running as long as you need. State accumulates naturally. Reset on demand.
  </Step>

  <Step title="mirra run <scenario.md> — for CI and agent validation">
    Execute a markdown scenario against provisioned mirrors. Get a pass/fail verdict and a satisfaction score. Gate your PR on the result.
  </Step>

  <Step title="@mirrahq/vitest — for your existing test suite">
    Drop a `withMirra()` wrapper into your Vitest config. Your existing tests run against mirrors instead of mocks. Zero code changes.
  </Step>
</Steps>

## Who Mirra is for

Mirra is built for engineering teams shipping integration code that touches real vendors — payments, email, SMS, auth, commerce. Teams with 5–50 engineers, 10+ third-party integrations, and increasingly heavy AI-assisted coding via Claude Code, Cursor, or Copilot.

If you've ever shipped a Stripe webhook handler that didn't verify signatures correctly, a Twilio retry loop that didn't back off, or a Resend bounce callback that got silently swallowed — this is built for you.

## Where to go next

<Columns cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Install the CLI and run your first mirror in under two minutes.
  </Card>

  <Card title="Scenarios" icon="file-lines" href="/concepts/scenarios">
    Learn the markdown scenario format and the \[D]/\[P] evaluation system.
  </Card>

  <Card title="Coding agents" icon="sparkles" href="/guides/coding-agents-mcp">
    Wire Claude Code, Cursor, or any MCP-compatible agent into a Mirra session.
  </Card>

  <Card title="Vitest plugin" icon="vial" href="/guides/vitest-plugin">
    Drop Mirra into an existing Vitest suite without changing test code.
  </Card>
</Columns>

<Note>
  Mirra is in **private beta**. Real usage requires an access request at [mirra.run/access](https://mirra.run/access). These docs are public and work standalone — no account required to read them.
</Note>