> ## Documentation Index > Fetch the complete documentation index at: https://docs.mistle.dev/llms.txt > Use this file to discover all available pages before exploring further. # Snapshots > Start sessions from prepared sandbox profile images ## Overview Snapshots are prepared sandbox images for published sandbox profile versions. They make new sessions start from a profile-specific image instead of rebuilding everything from the shared base image every time. A snapshot captures the result of applying a published profile version's runtime plan and setup script to a one-off sandbox, then stores the resulting provider image handle on that profile version. ## What Snapshots Are For Snapshots make sandbox startup faster and more predictable. They are useful when a sandbox profile needs repeatable setup before users start sessions, such as: * installing language runtimes or CLI tools * preparing agent configuration * applying setup scripts * baking common dependencies into the launch image Once a snapshot is ready, new sessions for that published profile version launch from the snapshot image. ## Lifecycle Snapshots are tied to sandbox profile versions. * Publishing a draft version queues the initial snapshot job. * Manual refresh queues a new snapshot job for an already published version. * Scheduled refresh can queue snapshot jobs for profiles that need regular rebuilds. * A profile version is not usable for new sessions until its published version has a usable snapshot image. * Failed refreshes keep the existing usable snapshot when one already exists. Only one queued or running snapshot job is allowed per profile version at a time. ## Check Snapshot Status Snapshot status is shown on the sandbox profile version. Use it when a profile is not available for new sessions. Common states to look for: * queued or running: Mistle is still preparing the snapshot * ready: new sessions can start from the prepared image * failed: inspect the setup script and snapshot output, then refresh the snapshot after fixing the profile Published sandbox profile snapshot panel showing a ready snapshot and refresh schedule If setup changes are needed, edit the draft profile version, test the setup script, and publish a new version. ## What Snapshots Are Not Snapshots are not per-session durable storage. They do not preserve the ongoing filesystem changes from a user's sandbox session. Use snapshots when many future sandboxes should start from the same prepared image. ## Next Steps * Read [Sandbox Profiles](/guides/sandbox-profiles) for the profile lifecycle. * Read [Sessions](/guides/sessions) for how users start agent work from a prepared profile.