# Upgrade Cotal

Upgrade an existing installation without recreating its space identity or losing its trust material.
Use the [upgrade history](/docs/upgrading/) for the migration instructions that apply to your source and target releases.

## Plan the upgrade

From the project's folder, record the current installation and mesh state:

```bash
cotal version
cotal status
```

Choose an exact target version, such as `0.N.P`, rather than a version range.
Read every applicable migration section between the installed version and the target release before changing the deployment.
Treat notes marked unreleased as unreleased until the target release includes them.

List the hosts that run the broker, auth service, managers, CLI, and connectors.
Use each release section's component order for a split deployment.
Plan a downtime window. The current upgrade contract does not promise rolling upgrades or mixed authority versions.

If a service manager or container owns the native stack's lifetime, check its launch command before upgrading.
Background startup is the default for `cotal up`; a supervisor that must own the stack needs `cotal up --foreground`.
See [Supervise the stack](/docs/supervise-processes/).

## Prepare for downtime

Save agent work and arrange a quiet maintenance window before stopping services.
Pause automatic restarts and new managed launches when the applicable migration requires them.

> **Warning: Check shutdown and backup limits first**
>
> Built-in `pty` seats stop with their manager, including a normal `cotal down`.
> An older manager may also have different shutdown guarantees.
> Read [Stop the stack](/docs/run-a-mesh/#stop-the-stack) before choosing the stop command.
> 
> A controller-owned stack cannot use the preserve, backup, or restore commands in this release.
> Use the deployment's supported protected backup procedure for its durable state and trust material.
> The [offline backup guide](/docs/backup-a-mesh/) describes the supported mesh types and their limits.



Take the snapshots required by the applicable release section before any migration writes occur.
A Cotal backup artifact contains no credentials or trust secrets, so protect the original trust material separately.
Stop components in the release section's stated order.
For an ordinary local whole-stack shutdown, use the procedure in [Run a mesh](/docs/run-a-mesh/#stop-the-stack).

## Install the target version

Use the same installation route and prefix that currently supply your `cotal` command.
Replace `<target-version>` with the exact version you selected.

### Shell installation

Read the [installer script](https://get.cotal.ai) before running it, then pin the target release:

```bash
curl -fsSL https://get.cotal.ai | sh -s -- --version <target-version> --no-setup
```

If the original installation used custom locations, supply those same locations again.
See [Install Cotal](/docs/installation/) for installer options and PATH checks.

### npm installation

For an npm installation, run:

```bash
npm install -g cotal-ai@<target-version>
```

Open a new terminal or use the installer's absolute launcher path if the shell still selects the previous installation.
Run `cotal version` and confirm that the selected binary is the target version before continuing.

## Reconcile the installation

From the prepared project folder, run the target version's command:

```bash
cotal update
```

This reconciles installed extensions and connector integrations with the running CLI's release.
It checks running-manager continuity before installation repair.
If it refuses, follow the reported remedy instead of removing credentials or reinstalling an unrelated copy.

`cotal update --check` only reports registry availability and recorded extension versions.
It installs and restarts nothing, so it does not replace this reconciliation step.
`cotal update --self` selects the validated latest release; use the pinned install commands above when you need a specific target.

## Restart the mesh

Complete the release-specific credential and state migrations before restarting components.
Start them in the order specified for that release.

For a local background stack, return to its existing project folder and run:

```bash
cotal up --detach
cotal version
cotal status --components
```

Reuse the existing project root. Do not run `space create` or `space add` to replace an existing local mesh during an ordinary upgrade.
A foreground service must retain its `--foreground` launch mode.
Restart or reconnect agent applications when the migration instructions require them to load the new connector.

Confirm the target binary and installed extension versions, then check the component report for absent, not-serving, or refused components.
A version report describes the selected installation; it does not prove that every previously running process loaded the new code.
Resume new work only after the required components are serving and the release-specific checks pass.

If a migration or restart fails, keep the failed step's evidence and use [Recover a mesh](/docs/recover-a-mesh/).
Installing an older package does not automatically undo credential or on-disk migrations.
Use the matching release's recovery instructions before restoring state or attempting a downgrade.