# GET /api/v2/budget-groups

List budget groups

- MCP id: budget-groups.index
- Scope: api:read:budget_groups
- Permission: budget_groups::read
- Rate cost: 1 unit, read bucket. `view=detail` makes it 3. Adds: `q` +2.
- Cache-Control: private, no-store

Returns the organisation's budget groups, sorted by name A→Z, each with the number of budgets filed under it.

Pass `view=detail` for the full payload at three read units instead of one; the two views are identical on this resource.

## Parameters
- view (string, optional): Which field set to render.
- per_page (integer 1 to 100, optional): Rows per page. At most 25 when `include` names a to-many relation; a larger value is 400 invalid-query-parameter.
- cursor (string, optional): Opaque keyset cursor from a previous page's links.next. Never construct one by hand.
- page (integer 1 to 1000, optional): Opt in to page-number paging: 1-based, at most 1000. Omit it, the default, to page by opaque cursor, which is what links.next hands you. Cannot be combined with cursor. Published only on collections that count their rows on every request.
- filter[created_at] (timestamp (YYYY-MM-DDThh:mm:ssZ), optional): Creation timestamp. Pair with `sort=id` for a stable full export. Operators: = gte lt.
- filter[updated_at] (timestamp (YYYY-MM-DDThh:mm:ssZ), optional): Last-write timestamp. Use for incremental sync. Operators: = gte lt.
- q (string, optional): Free-text search over `name`. At most one substring match per request: `q` together with a `contains` filter is 400 invalid-query-parameter.
- sort (string, optional): Up to three keys, comma-separated, each optionally prefixed with `-` for descending.
- X-Request-Id (header, optional): A correlation id of your own. It is recorded in our logs next to the server's request id but never returned: the response header always carries the server's id. A value that does not match the pattern is discarded silently, never rejected.
- If-None-Match (header, optional): The ETag a read is conditional on. A match is answered 304 with no body.

## Response 200
- id (integer, required): Unique identifier.
- name (string ≤ 255, required): Budget group name as shown in the UI. This is the default sort key.
- icon (string ≤ 255, required): Icon identifier rendered beside the group, e.g. `heroicon-o-rectangle-stack`.
- created_at (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Creation timestamp.
- updated_at (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Last-write timestamp; use for incremental sync.
- budgets_count (integer ≥ 0, required): Number of budgets filed under this group.
- links (BudgetGroupLinks, required)
  - self (url, required): The canonical URI of this record.
  - budgets (url, required): Budgets filed under this group.

## Errors
- 403 forbidden-by-policy | insufficient-permission | insufficient-token-scope: Forbidden.
- 304 : Not modified.
- 400 idempotency-key-required | invalid-cursor | invalid-query-parameter | malformed-request | unsupported-parameter: Bad request.
- 401 token-expired | unauthenticated: Unauthenticated.
- 404 endpoint-not-found | resource-not-found: Not found.
- 406 not-acceptable: Not acceptable.
- 429 rate-limit-exceeded: Too many requests.
- 500 internal-error: Server error.
- 503 tenant-unavailable: Service unavailable.

## Example
```bash
curl -G \
  'https://<your-url>/api/v2/budget-groups' \
  --data-urlencode 'q=development' \
  --data-urlencode 'sort=name' \
  -H 'Authorization: Bearer <token>' \
  -H 'Accept: application/json'
```