feat: image variants engine

docs/api.md

@@ -62,12 +62,13 @@ never changes the response or the change itself.
 | Category | Actions |
 | --- | --- |
 | `articles` | `article.create`, `article.edit`, `article.publish`, `article.unpublish`, `article.delete` |
-| `media` | `media.upload`, `media.rename`, `media.delete`, `media.merge`, `media.purge` |
+| `media` | `media.upload`, `media.rename`, `media.delete`, `media.merge`, `media.purge`, `media.variant_create`, `media.variant_update`, `media.variant_delete`, `media.variant_enable`, `media.variant_disable`, `media.variant_purge` |
 | `users` | `user.register`, `user.verify`, `user.update_profile`, `invite.create`, `invite.cancel`, `invite.renew`, `invite.accept` |
 | `system` | `system.media_purge` (scheduled), `system.update_checked`, `system.update_downloaded`, `system.restart_requested`, `system.activity_cleanup`, `system.activity_retention_changed` |
 
-Target types: `article`, `image`, `user`, `invite`, `api_key` and `release` (id and name are the tag).
-Only the fields `title`, `online`, `body`, `filename` and `display_name` appear in `changes`, with the
+Target types: `article`, `image`, `image_variant` (id and name are the variant name), `user`, `invite`,
+`api_key` and `release` (id and name are the tag).
+Only the fields `title`, `online`, `body`, `filename`, `display_name`, `width`, `height`, `fit`, `format` and `quality` appear in `changes`, with the
 kinds `text` and `body`; a body edit carries a signed character count delta and never the text. A
 change that leaves a value as it was (same body, same publish state, same file name, same display
 name) records nothing. Params: `media.merge` and `media.purge` and `system.media_purge` carry
@@ -89,6 +90,31 @@ codes, article bodies, file bytes, storage paths and asset urls are never record
 Article routes accept `?format=markdown|html|json` (default `markdown`). `GET /v1/media/` accepts
 `q`, `hash`, `cursor`, `filter`, `sort` and `limit`.
 
+## Image variants
+Owners and admins manage named variants of the stored images. These routes are session only (no API
+key) and sit behind the verified-user check; any other role gets 403 "Only owners and admins can do
+this." Behaviour, caching and the public `?v=<name>` contract are in [image-variants.md](image-variants.md).
+
+| Route | Purpose |
+| --- | --- |
+| `GET /v1/image-variants` | `{ "items": [...] }`, ordered by name. |
+| `POST /v1/image-variants` | Create. 201 with the variant. 409 when the name exists. |
+| `PUT /v1/image-variants/{name}` | Replace the definition (the name in the body is ignored). 200 with the variant and `purged_files`. |
+| `PATCH /v1/image-variants/{name}` | `{ "enabled": true }` or `{ "enabled": false }`. Keeps the generated files. |
+| `DELETE /v1/image-variants/{name}` | 204. Removes the definition and its generated files. |
+| `POST /v1/image-variants/{name}/purge` | `{ "purged_files", "purged_bytes" }`. Keeps the definition. |
+
+A variant is `{ name, width, height, fit, format, quality, generate_on_upload, enabled,
+generated_files, cache_size, created_at, updated_at }`. `width` and `height` are 1 to 8000 or `null`
+(at least one is required), `fit` is `cover`, `contain` or `inside` (default `cover`), `format` is
+`original`, `jpeg`, `png` or `webp` (default `original`), `quality` is 1 to 100 (default 82, `null`
+for `png`), `generate_on_upload` defaults to `false`, `enabled` to `true`, and `cache_size` is in
+bytes. A `PUT` that omits `generate_on_upload` or `enabled` keeps the stored value.
+
+Errors are plain text: 400 for a body that is not valid JSON, 404 "Variant not found", 409 "A variant
+named “thumb” already exists. Choose another name." and 422 with one sentence for the first invalid
+field (name, width and height, fit, format, quality).
+
 ## Errors
 Every error is a plain-text body with one sentence; the status is in the HTTP status line. The
 statuses are 400, 401, 403, 404, 409, 429 and 500. Messages are listed on the Integration page.