# PATCH /api/v2/subtasks/{subtask}

Update a subtask

- MCP id: subtasks.update
- Scope: api:write:project_management
- Permission: project_management::manage_work_items
- Rate cost: 1 unit, write bucket. A write costs the same whatever `view` you ask for.
- Cache-Control: private, no-store

Partially updates one subtask: absent keys are untouched.

This covers both plnnrly's edit action (title and description) and its tick-off toggle (`is_resolved`); there is no actions/resolve action. Send `If-Match` with the `ETag` from your last read to detect a concurrent edit, which answers `412`; a subtask has no `version` field, so its `ETag` is derived from `updated_at`, and the `ETag` in the response is the one to send next. `work_item_id` and order are not accepted: a subtask cannot be moved to another work item, and there is no way to reorder a checklist through the API. Note the API is stricter than plnnrly here: plnnrly lets a user merely assigned to a work item tick its subtasks, while this endpoint requires `project_management::manage_work_items`.

## Parameters
- subtask (integer, path): The Subtask's numeric id.
- view (string, optional): Which field set to render.
- 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-Match (header, optional): The ETag a write is conditional on. A stale validator is 412 precondition-failed.

## Request body
- title (string ≤ 255, required): Subtask title, as shown on the checklist row. This is the field `?q=` searches.
- description (string or null, optional): Optional note on the subtask. HTML from the rich editor, sanitised on read and on write. Null when the subtask is just a title.
- is_resolved (boolean, optional): Whether the subtask is ticked off.

Unknown keys are refused with `422` validation-failed, naming the key.

## Response 200
- id (integer, required): Unique identifier.
- work_item_id (integer, required, server-assigned): The work item whose checklist this subtask belongs to. Taken from the path on create and not writable.
- title (string ≤ 255, required): Subtask title, as shown on the checklist row. This is the field `?q=` searches.
- description (html or null, required, detail only): Optional note on the subtask. HTML from the rich editor, sanitised on read and on write. Null when the subtask is just a title.
- is_resolved (boolean, required): Whether the subtask is ticked off.
- order (integer, required, server-assigned): Position in the work item's checklist. Assigned on create as the next position in that checklist, changed only by dragging in plnnrly, and not writable.
- 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.
- work_item (Ref or WorkItemSummary, required): The work item this subtask hangs off.
- links (SubtaskLinks, required)
  - self (url, required): The canonical URI of this record.

## Errors
- 403 forbidden-by-policy | insufficient-permission | insufficient-token-scope: Forbidden.
- 412 precondition-failed: Precondition failed.
- 415 unsupported-media-type: Unsupported media type.
- 422 unprocessable-relationship | validation-failed: Unprocessable content.
- 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 -X PATCH \
  'https://<your-url>/api/v2/subtasks/1' \
  -H 'Authorization: Bearer <token>' \
  -H 'Accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'If-Match: *' \
  -d '{
    "is_resolved": true
  }'
```