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

# Backwards compatibility

> How the API evolves without breaking integrations.

Ionic keeps existing integrations working as the API evolves. New behavior is added in ways that let existing clients continue to run.

## Compatible changes

These changes are safe for clients that ignore unknown fields and handle unknown enum values:

* Adding endpoints.
* Adding optional request fields.
* Adding response fields.
* Adding enum values.
* Adding error codes.
* Changing response field order.
* Changing opaque token or cursor formats.

## Breaking changes

These changes require notice and a migration path:

* Removing endpoints.
* Renaming request or response fields.
* Changing field types.
* Making optional request fields required.
* Removing enum values.
* Changing authentication behavior.
* Changing error response structure.

## Client guidance

* Ignore unknown response fields.
* Handle unknown enum values.
* Treat IDs, tokens, client secrets, and cursors as opaque.
* Use idempotency keys for retryable mutations.
* Read errors by machine-readable `code`, not only by message text.