---
title: "Compare Upload Against Prior"
method: POST
path: "/v1/history/delta"
tags: ["history"]
---

# Compare Upload Against Prior

`POST /v1/history/delta`

## Request

- Base URL: `https://api.claims.zicron.ai`
- URL: `https://api.claims.zicron.ai/v1/history/delta`
- Auth: none declared

Upload a file, find its prior extraction by content hash, and return the delta.

This does NOT run a new extraction — it compares the most recent stored
extraction for this content against the one before it.

## Response `200`

Successful Response

- DeltaResponse: Structured diff between two extraction outputs.
  - `added_fields` object
  - `removed_fields` object
  - `changed_count` integer
  - `unchanged_count` integer
  - `summary` string

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/zicron/apis/zicron-api.md) · [All operations](https://skmtc.dev/zicron/apis/zicron-api/llms.txt) · [OpenAPI document](https://skmtc.dev/zicron/apis/zicron-api/revisions/abe62e22aa46?raw)