feat: articles pagination

docs/api/articles.md

@@ -13,6 +13,37 @@ Every route that returns an article accepts the optional `format` query paramete
 
 Visibility is unchanged: anonymous and unverified callers only see online articles, and an offline article answers `404 Article not found`.
 
+## Pagination, search and counts
+
+`GET /v1/article/` always answers one page inside an envelope, with or without query parameters:
+
+```json
+{
+  "items": [],
+  "total": 30,
+  "page": 1,
+  "size": 25,
+  "counts": { "all": 30, "online": 30, "draft": 0 }
+}
+```
+
+| Parameter | Values | Default |
+| --- | --- | --- |
+| `page` | integer >= 1 | `1` |
+| `size` | `5`, `25`, `50` or `100` | `25` |
+| `q` | up to 200 characters, matched anywhere in the title, ignoring case and accents | none |
+| `status` | `online` or `draft` | none |
+| `sort` | `title`, `status`, `created_at` or `updated_at`, then `:asc` or `:desc` (lowercase, for example `title:asc`) | `updated_at:desc` |
+
+- `items` is `[]` when empty, never `null`. Each item is the article object below.
+- Items follow `sort` (default `updated_at:desc`) across the whole list before paging. `title` ignores case, `status` orders on online state (`status:asc` puts drafts first), and every ordering ends with `id` descending so pages never overlap.
+- `total` is the number of visible articles matching `q` and `status`, before paging. `page` and `size` echo the values applied.
+- `counts` ignores `q` and `status`, so tab counts do not move while searching. For anonymous and unverified callers `all` equals `online` and `draft` is `0`, and `status=draft` answers `items: []` and `total: 0`.
+- A page beyond the last answers `200` with `items: []` and the real `total`.
+- An invalid `page`, `size`, `status`, `sort` or an over-long `q` answers `400` with the plain-text message `The request cannot be processed due to a mismatch in the format of the body.` An invalid `format` is reported first.
+
+Breaking change: this route used to answer a bare JSON array. Clients must read the `items` property.
+
 ## The `format` parameter
 
 | Value | `body` | `body_format` |