---
title: Versions
description: "Every save of an agent is a numbered version. Read the ledger, diff any two versions and roll back to an earlier one."
---

**Versions**, under **Release** in the workspace sidebar, is the history of the agent:
every saved change, newest first, with a diff of exactly what changed and two ways
back. Use it to find out what a colleague changed, to compare the prompt before and
after a regression, and to restore a version that worked.

## The ledger

Versions are numbered `v<major>.<revision>`; the revision goes up by 1 on every save.
Publishing starts a new major, and that entry is marked **Published**. An agent that
has never been published can show a single number instead, such as `v4`.
The first entry is marked **Created** with the note **Initial configuration**;
the most recent is marked **Latest**, and one restored by a rollback is marked
**Restored**. Entries are grouped by day, **Today**, **Yesterday**, then the date,
each with its time.

Each entry names up to three fields that changed, such as **System Prompt**,
**Opening Message**, **Amd Timeout** or **Post-Call Outcomes**, with **+N** when there
are more, and who saved it. The count at the top right is the total;
**Refresh** reloads the list after someone else has saved. Long histories are split
into pages.

![The version ledger, newest first, with the changed fields on each entry.](/media/test-and-improve/version-ledger.webp)

## Read a diff

Choose an entry to open its detail on the right. The panel is headed with the version
number, **Created** or **Updated**, **Latest** if it is the newest, and the author and
time. Below it, two selectors, **Previous version** and **Next version**, set the pair
being compared; by default they are the entry and the one before it, so the diff is
what that save changed. Pick any other pair to compare across several saves.

Each changed field is a row:

- **+** a field that gained a value, with the value shown, such as **Amd Timeout 10**.
- **−** a field that lost its value.
- **~** a field that was edited, with a count of changed lines. Text fields such as
  **System Prompt** and **Opening Message** expand to a line diff: removed lines
  struck through, added lines highlighted.

The system prompt is shown as one text with `<<<CALLAB:IDENTITY>>>`, `<<<CALLAB:TASKS>>>`
and `<<<CALLAB:GUARDRAILS>>>` markers between the three fields of the editor; that is
how the agent receives it.

The close button at the top right of the panel returns to the ledger.

<video src="/media/test-and-improve/version-diff.mp4" autoplay loop muted playsinline></video>

*Opening a version and comparing it with the one before.*

## Roll back, or undo one change

On any version other than the latest, the detail panel has two more buttons:

| Button | What it does |
|---|---|
| **Rollback to this version** | Makes the agent identical to this version: every field, not just the ones in the diff. |
| **Undo this change** | Rolls the agent back to the version just before this one. Every field returns to that version, so changes saved after this one are reverted too. |

Either button opens a confirmation, **Rollback to Version N?**, listing how many
fields will change with each field's **Current** value and its value **After
restore**. Choose **Rollback** to confirm. The restore is an ordinary save: it adds a
new entry at the top of the ledger rather than deleting anything, so a rollback can
itself be rolled back, and the diff of the new entry shows exactly what was
restored.

![Rollback to this version and Undo this change on an older version.](/media/test-and-improve/version-rollback.webp)

1. **Find the last good version**

    Open entries from the top down and read the diff until you reach the save that
    introduced the problem.

2. **Roll back**

    On the save that introduced the problem, choose **Undo this change**, or open the
    version before it and choose **Rollback to this version**; both restore that
    earlier version. Any later changes you want to keep have to be made again.

3. **Verify**

    The ledger gains a new **Latest** entry. Open it and check the diff shows the
    fields you expected, then run a [browser test](/test-and-improve/testing-in-the-browser).

## Behaviour and limits

- Versions are per agent and cover everything under **Settings**, **Advanced**,
  **Tools**, **Outcomes** and, for flow agents, **Flow**. Widget changes can appear
  as **Widget Config**. Evaluation scenarios are not versioned.
- The **Latest** version is the one every channel uses; see
  [Publishing](/test-and-improve/publishing).
- Versions cannot be deleted or renamed.

## Related

- [Publishing](/test-and-improve/publishing)
- [Launch checklist](/test-and-improve/launch-checklist)
- [Anatomy of an agent](/build/anatomy-of-an-agent)
- [Core concepts](/get-started/core-concepts)