# Compatibility subpath (/docs/reference/compatibility)



Import the migration bridge explicitly.

```ts title="src/email.ts"
import { createEmailClient } from "@opencoredev/email-sdk/compat";
```

The v1 root does not export legacy provider vocabulary or result aliases.

## Translated surfaces [#translated-surfaces]

Compat accepts and translates:

* `providers` and `defaultProvider`
* per-send `provider`, `fallbackAdapters`, and `fallbackProviders`
* client `fallback: string[]`
* `retry.retries` and per-send `retries`
* `sendBatch` and legacy batch item routing fields
* message-level `idempotencyKey`
* message-level `recipientVariables`
* result `provider` and `messageId`
* legacy adapters without a capability declaration
* legacy hooks, middleware, and plugin contexts

Result aliases are non-enumerable getters. Compat warnings print once per deprecated feature only in development, never in production or tests.

## Safety differences that compat does not undo [#safety-differences-that-compat-does-not-undo]

Compat keeps v1 delivery certainty. Legacy fallback arrays become `{ adapters, onUnknownDelivery: "stop" }`. An ambiguous outcome does not automatically advance.

Legacy adapters receive permissive inferred capabilities because v0 had no declarations. Treat that as a migration convenience and add explicit v1 capabilities before removing compat.

## Removal plan [#removal-plan]

The bridge exists for the v1 major and is excluded from the v2 contract. Do not build new features against it.

<Card title="v0 to v1 migration" href="/docs/guides/migrate/v0-to-v1" description="Replace every translated surface with its v1 form." />