Asset container upload validation (validate: key) isn't documented

[JasperWelsing]

Asset container upload validation (validate: key) isn't documented

Asset containers support a validate: key in their YAML config (e.g. content/assets/<container>.yaml) that caps/validates uploads made directly through the Assets Browser. This is the only way to restrict those uploads — blueprint field-level validate rules only apply when uploading through that specific field's picker on an entry form, not through Assets → [container] → Upload. I couldn't find this documented on statamic.dev, and it isn't mentioned in config/statamic/assets.php.

Example

# content/assets/assets.yaml
title: Media
disk: assets
allow_uploads: true
validate:
  - max:20480   # KB — rejects uploads over 20MB

Oversized uploads are rejected with a normal 422 validation error, rendered inline by the Assets Browser UI.

Source reference

- Statamic\Assets\AssetContainer::validationRules() — getter/setter, backed by fluentlyGetOrSet('validation').
- Statamic\Stache\Stores\AssetContainersStore::makeItemFromFile() — reads validate from YAML.
- Statamic\Assets\AssetContainer::fileData() — writes it back out as validate.
- Statamic\Http\Controllers\CP\Assets\AssetsController::store() — merges validationRules() into the file validation rules.

Load/save are consistent (both use validate), so this isn't a bug — just a naming mismatch between the YAML key and the PHP accessor (validationRules()), which makes the feature hard to discover.

Suggestion

Document the container-level validate: key on the Assets / Asset Containers page on statamic.dev.