# PATCH /api/v2/furlough-balance-mutations/{furlough_balance_mutation}

Update a furlough balance mutation

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

Partially updates a mutation: absent keys are untouched, an empty body is rejected, and an unknown key is a `422`.

This is the API's only approval surface: `{"is_approved": true}` approves, `{"is_approved": false}` denies, and either needs `furlough::manage`, which is also this operation's own permission, so a plain employee cannot edit even their own pending request here although plnnrly lets them while it is still in the future. A manager deciding on their own mutation answers `403` `forbidden-by-policy`. ⚠ An approval through this endpoint is a plain field write: unlike the approval screen in plnnrly it does not split a request that spans two balance years into one mutation per year, and it sends the employee no e-mail. ⚠ `start` and `end` move as a pair (send both or neither), and neither rewrites `year`, so a period moved into another year keeps counting against the old balance year until `year` is sent too. Send `If-Match` with the `ETag` from your last read to detect a concurrent edit, which answers `412`. Treat it as best-effort only: this resource carries no concurrency token, and `updated_at` is second-precision, so two writes inside the same second are indistinguishable.

## Parameters
- furlough_balance_mutation (integer, path): The FurloughBalanceMutation'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
- year (integer 1970 to 2200, optional): The balance year this mutation counts against. It is not derived from `start`: every balance sum counts by this year, so a mutation whose period moves into another year keeps counting against the year sent here until `year` is sent too.
- type (string, optional): Which leave balance this mutation moves. Regular and special leave are separate balances and never offset one another.
- minutes (integer, optional): The signed balance delta in minutes. Negative consumes balance (a leave request); positive grants it (a manager's adjustment, which requires the `furlough::manage` permission to write). The API never computes this from the employee's working week or the organisation's free days: send the exact number of minutes you mean. A positive value grants balance and requires the `furlough::manage` permission; a caller with only `furlough::create_for_yourself` may write a negative value (a leave request) or zero. On a `special` mutation, the resulting special-leave balance for the year may not go negative.
- start (timestamp (YYYY-MM-DDThh:mm:ssZ), optional): Start of the period this mutation covers, in UTC. Equal to `end` on a manual balance adjustment, which covers no period at all. Required when end is present.
- end (timestamp (YYYY-MM-DDThh:mm:ssZ), optional): End of the period this mutation covers, in UTC. Never before `start`, and equal to it on a manual balance adjustment. Required when start is present. Must be on or after start.
- description (string, optional): The employee's or manager's own words for this mutation: the reason for the leave, or what the adjustment is for. The only field `?q=` searches.
- is_approved (boolean or null, optional): Approval state, in three values: `null` means pending approval, `true` approved, `false` denied. The balance counts pending and approved mutations alike and ignores denied ones. Writing this field at all requires the `furlough::manage` permission.

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

## Response 200
- id (integer, required): Unique identifier.
- user_id (integer, required, server-assigned): The employee this mutation belongs to. Always the authenticated user on create and not writable.
- acceptor_id (integer or null, required, server-assigned): The user who approved this mutation, set by the server when the mutation resolves to approved. Null while it is pending, and left `null` by a denial. Resolve the name through `GET /api/v2/users/{user}`.
- year (integer, required): The balance year this mutation counts against. It is not derived from `start`: every balance sum counts by this year, so a mutation whose period moves into another year keeps counting against the year sent here until `year` is sent too.
- type (string, required): Which leave balance this mutation moves. Regular and special leave are separate balances and never offset one another.
- minutes (integer, required): The signed balance delta in minutes. Negative consumes balance (a leave request); positive grants it (a manager's adjustment, which requires the `furlough::manage` permission to write). The API never computes this from the employee's working week or the organisation's free days: send the exact number of minutes you mean.
- start (timestamp (YYYY-MM-DDThh:mm:ssZ), required): Start of the period this mutation covers, in UTC. Equal to `end` on a manual balance adjustment, which covers no period at all.
- end (timestamp (YYYY-MM-DDThh:mm:ssZ), required): End of the period this mutation covers, in UTC. Never before `start`, and equal to it on a manual balance adjustment.
- description (string, required, multiline): The employee's or manager's own words for this mutation: the reason for the leave, or what the adjustment is for. The only field `?q=` searches.
- is_approved (boolean or null, required): Approval state, in three values: `null` means pending approval, `true` approved, `false` denied. The balance counts pending and approved mutations alike and ignores denied ones. Writing this field at all requires the `furlough::manage` permission.
- user (Ref or UserSummary, required): The employee this mutation belongs to. Expanding it with `?include=user` additionally requires the `users::read` permission and a token scope covering the users prefix.
- 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.
- links (FurloughBalanceMutationLinks, 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/furlough-balance-mutations/1' \
  -H 'Authorization: Bearer <token>' \
  -H 'Accept: application/json' \
  -H 'Content-Type: application/json' \
  -H 'If-Match: *' \
  -d '{
    "is_approved": true
  }'
```