> For the complete documentation index, see [llms.txt](https://docs.tumbler.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tumbler.app/changelog.md).

# Changelog

## Who this is for

Providers who need to track public contract changes and plan compatibility tests.

## What you can do

* See which fields and rules were added or changed.
* Plan migrations and compatibility tests.
* Check effective dates for changes.

## Examples

* Adding a new flag to `meta.capabilities`.
* Announcing subscription URL migration.
* Introducing a **\[PAID]** feature.

## See also

* [README.md](/readme.md)
* [features/overview.md](/features/overview.md)
* [operations/mirrors-and-migration.md](/after-first-launch/mirrors-and-migration.md)

## History

* **2026-07-01** - Added the English documentation branch `provider-docs/en/` for a separate GitBook space/variant. API behavior did not change.
* **2026-07-01** - Reworked the documentation around the provider journey: existing subscription URL first, then `tumbler://add?link=...`, raw HTTPS or `crypt3`, and only then response formats, metadata, and advanced features. ACC callbacks were consolidated into one canonical section `features/acc-callbacks.md`. API behavior did not change.
* **2026-03-23** - Backend client API behavior changed for `POST /v1/subscriptions/add`: repeated `add` from the same installation for an already linked subscription now returns `409 SUBSCRIPTION_ALREADY_ADDED` with a recommendation to use `/v1/subscriptions/sync` or `/v1/subscriptions/restore`. Provider subscription response format did not change.
* **2026-03-22** - Public backend API added diagnostic endpoint `GET /ping`, which returns the current server date as `YYYY-MM-DD` (UTC). This does not affect the provider subscription contract.
* **2026-03-09** - Initial provider documentation scaffold; rules and structure were recorded.


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