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

# Review Changes: preview before every mutation

> Review Changes is Gandalf's mandatory preview step. It lists writable items, unsupported evidence, risk, and rollback instructions before any apply.

Review Changes is the user-facing preview step that runs before any Gandalf mutation. It applies to restore-backed applies and to provider-backed setup actions in the TUI. The rule is simple: no mutation happens without a Review Changes surface that describes exactly what will change.

## What Review Changes shows

* **Writable items**: the concrete changes an apply would make, grouped by evidence kind.
* **Unsupported items with reasons**: evidence Gandalf will not touch. Instead of falling back to unsafe generic file replacement, unsupported kinds stay observe-only with a specific reason.
* **Risk metadata**: per-item severity (critical, high, medium, low, none) plus a summary total.
* **Rollback instructions**: per-item guidance so you know how to undo before you apply.

## Review Changes is not apply authority

A Review Changes surface previews a plan, but the plan is not frozen. Any mutation refreshes or revalidates the underlying plan at apply time so what you reviewed still matches reality. If the world has changed, Gandalf refuses the stale apply.

## Where you see it

* **`gandalf restore --dry-run`** prints the restore plan as text or JSON. This is the default when `--apply` is omitted:
  ```bash theme={null}
  gandalf restore --snapshot baseline --dry-run --agent codex --scope user --project .
  ```
  The output lists snapshot, target project, target home, writable change count, unsupported item count, and per-item plan entries with risk and rollback.
* **`gandalf restore --apply --experimental`** re-runs the plan build inside the apply path before writing. Add `--rollback` to auto-undo on failure.
* **The TUI Changes tab**: every provider-backed action in Console tabs (Hooks, Plugins, Marketplace, Skills, MCP Servers) routes through Review Changes before writing. There is no bypass in the TUI.
* **`gandalf apply`** for the team manifest prints a "Review Changes before Apply" list of drift items and prompts for confirmation unless `--yes` is passed.

## Marketplace-originated Review Actions

For agent-native marketplace or source entries, Review Changes flows can start from source metadata. The first safe version stays non-mutating: it produces reviewed guidance rather than executing install, update, uninstall, add-source, or remove-source. A concrete provider is required before those actions become available. See [providers](/concepts/providers) and [marketplace](/concepts/marketplace).