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

# Versions

> Per-item version history with time-aware thinning and a hard cap

Every `PATCH /items/{id}` increments the item's `version` and persists a snapshot of the prior state. The server keeps those snapshots so clients can read history and recover from unintended overwrites, but thins them over time so a frequently-edited item doesn't accumulate unbounded storage.

For per-field policy on concurrent edits, see [Conflicts](/concepts/conflicts).

## Version snapshots

List snapshots via `GET /items/{id}/versions`. Each snapshot carries:

* The version number.
* The timestamp of the update that produced it.
* The full properties at that version.
* The credential (`source`) that wrote it.

Snapshots are per-item and per-space; edges and extensions don't snapshot.

## Thinning policy

Snapshots are thinned on a rolling schedule with four windows, configured via environment variables:

| Window        | Retention                           | Variable                       |
| ------------- | ----------------------------------- | ------------------------------ |
| Recent        | Every snapshot kept                 | `VERSION_RECENT_DAYS`          |
| Daily         | One snapshot per calendar day (UTC) | `VERSION_DAILY_SNAPSHOT_DAYS`  |
| Weekly        | One snapshot per ISO week           | `VERSION_WEEKLY_SNAPSHOT_DAYS` |
| Beyond weekly | Dropped                             | —                              |

The most recent snapshot is never thinned, even if all windows expire — an item always has at least its latest pre-update state available.

## Hard cap

`VERSION_MAX_VERSIONS` caps the snapshot count per item. When kept snapshots exceed the cap, the oldest are dropped first — even inside the recent window. Protects against pathological edit loops.

## When thinning runs

The thinning job runs on a server-wide interval controlled by `VERSION_THINNING_INTERVAL_MS`. Thinning is advisory — snapshot reads see whatever survives the most recent run. See [Configuration](/self-hosting/configuration) for the full variable list and defaults.

## Per-type overrides

Types can declare their own `version_policy` block that overrides any of the four fields per-type. Custom `core.highlight` snapshots might keep history tighter than bulky `core.file.video` metadata; the per-type policy merges field-by-field over the global defaults.

## Restoring from a version

The server doesn't expose a one-shot "revert to version N" endpoint. Restoring means fetching the snapshot at version N and re-sending its properties through `PATCH /items/{id}` — the restore becomes a new forward version, preserving audit continuity.