---
title: "tool si.work.backfill"
description: "a source, an access method, a window, a plane: the job; then partitions carrying the window."
section: reference
address: /reference/tools/si-work-backfill
contract: 0476e35e6e275db5
---

# tool si.work.backfill

a source, an access method, a window, a plane: the job; then partitions carrying the window.

[figure: Over MCP, si.work.backfill takes BackfillInput and returns a card whose body is Job.]

the job; then partitions carrying the window. The call needs the work grant at the brand rung.



| | |
|---|---|
| input | [BackfillInput](/concepts/backfillinput) |
| result | a card whose body is [Job](/concepts/job) |
| read-only | no |
| destructive | no |
| card address | `ui://scale-intelligence/cards/Job` |
| HTTP route | [`/v1/work/backfill`](/reference/work/backfill) |





| field | type | required | note |
|---|---|---|---|
| `source` | `id` | yes |  |
| `access_method` | `id` | yes |  |
| `window` | [Window](/concepts/window) | yes |  |
| `plane` | [Plane](/concepts/plane) | yes |  |
| `reading` | `text` | no | the hash of the procedure reading the backfill runs over, filled by the platform from the newest reading of the source through the way's connector; a caller leaves it empty |