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

# Versioning

> Every agent change creates an immutable snapshot — roll forward and back without redeploying clients

Agents on HasteKit are versioned automatically. Every time you click **Save**, the current configuration becomes a new immutable snapshot. Old snapshots are kept forever and can be re-pointed to by an [alias](/docs/gateway/agent-builder/alias) at any time.

<Frame>
  <img src="https://mintcdn.com/hastekit/890s5wy2NHvxQLSN/images/agent-builder/versions.png?fit=max&auto=format&n=890s5wy2NHvxQLSN&q=85&s=788148dd9ae6481e423c3aa1aa9869e0" alt="Versions tab" width="3890" height="1652" data-path="images/agent-builder/versions.png" />
</Frame>

## How versions work

* **Version 0 = `$LATEST`** — the mutable working copy. Every save on the Model / System Prompt / Tools / Skills / Memory / Handoffs / Output Schema / Connectors / Knowledge / Codebases / History tabs updates `$LATEST`.
* **Click "Create New Version"** on the Versions tab to freeze the current `$LATEST` into a numbered snapshot (1, 2, 3, …). Future edits go back to `$LATEST`.
* Numbered versions are **immutable** — once published they never change.

## What versions enable

* **Stable references** — clients call `my_agent@5` or `my_agent@production` instead of "whatever's in `$LATEST` right now."
* **Safe rollouts** — point a [production alias](/docs/gateway/agent-builder/alias) at the new version; if it misbehaves, repoint the alias back. Clients don't redeploy.
* **A/B testing** — split traffic across two versions using a weighted alias.
* **Audit and rollback** — every change is a discrete artifact you can review or re-activate.

## What's captured in a version

Everything on the agent except the **General** info (name, max iteration, runtime). Specifically: model and parameters, system prompt, output schema, history config, knowledge bases, codebases, memory service, tools, MCP servers, OpenAPI servers, connector actions, skills, and handoffs.

Each version is fully self-contained — restoring an old version restores the exact tool catalog and prompts that were active at the time.