`documents.assets.prepare`

Start uploading an image for agreements, such as a logo, a diagram or a signature stamp: PNG or JPEG up to 10 MB and 6,000 pixels on a side, with its SHA-256. Pass saved: true to keep it in the library to reuse. Returns the image and, unless the organization already has this exact image, a private upload link: PUT the bytes there with their content type, then call documents.assets.confirm. Place a confirmed image in a template with a line ![Alt text](asset:<id>?width=50&align=center); width is 10–100 percent of the text width (default 100) and align is left, center or right (default center).

POST/api/v1/accounting/documents.assets.prepare

Permissions

accounting:readaccounting:write

Who can call it

admin, finance

Retries

Idempotency key required

MCP

accounting_documents_assets_prepare

Fields

filenamestringRequired
The file's name, including its extension.
1–200 characters
mimeTypeenumRequired
The file's type, such as image/jpeg or application/pdf.
image/pngimage/jpeg
sizeBytesintegerRequired
The file's size in bytes.
1 to 10485760
sha256stringRequired
The SHA-256 hash of the file's exact bytes, as 64 lowercase hex characters.
SHA-256 hash as 64 lowercase hex characters
titlestring
A short title.
at most 120 characters
savedboolean
Default false
idempotencyKeystringRequired
Any unique text you generate once per intended change, so a retried request only happens once. Send it as the Idempotency-Key header instead if you prefer; if you send both they must match.
8–200 characters

curl https://app.getoatmilk.com/api/v1/accounting/documents.assets.prepare \
  -H "Authorization: Bearer $OATMILK_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
  "filename": "receipt.png",
  "mimeType": "image/png",
  "sizeBytes": 1,
  "sha256": "9f2b5c1d7e3a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c"
}'

const response = await fetch("https://app.getoatmilk.com/api/v1/accounting/documents.assets.prepare", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.OATMILK_API_KEY}`,
    "Content-Type": "application/json",
    "Idempotency-Key": crypto.randomUUID(),
  },
  body: JSON.stringify({
    "filename": "receipt.png",
    "mimeType": "image/png",
    "sizeBytes": 1,
    "sha256": "9f2b5c1d7e3a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c"
  }),
});
const { data, error } = await response.json();
if (!response.ok) throw new Error(`${error.code}: ${error.message}`);
console.log(data);

import os
import uuid

import requests

response = requests.post(
    "https://app.getoatmilk.com/api/v1/accounting/documents.assets.prepare",
    headers={
        "Authorization": f"Bearer {os.environ['OATMILK_API_KEY']}",
        "Idempotency-Key": str(uuid.uuid4()),
    },
    json={
        "filename": "receipt.png",
        "mimeType": "image/png",
        "sizeBytes": 1,
        "sha256": "9f2b5c1d7e3a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c",
    },
    timeout=30,
)
payload = response.json()
if not response.ok:
    raise RuntimeError(f"{payload['error']['code']}: {payload['error']['message']}")
print(payload["data"])

Response

{
  "data": { … }
}

Try it

Checks your input with this action’s real schema and answers like the API, with synthetic data. No key needed, and nothing changes.

Input

POST/api/v1/accounting/documents.assets.prepare

curl https://app.getoatmilk.com/api/v1/accounting/documents.assets.prepare \
  -H "Authorization: Bearer $OATMILK_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
  "filename": "receipt.png",
  "mimeType": "image/png",
  "sizeBytes": 1,
  "sha256": "9f2b5c1d7e3a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c"
}'

const response = await fetch("https://app.getoatmilk.com/api/v1/accounting/documents.assets.prepare", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.OATMILK_API_KEY}`,
    "Content-Type": "application/json",
    "Idempotency-Key": crypto.randomUUID(),
  },
  body: JSON.stringify({
    "filename": "receipt.png",
    "mimeType": "image/png",
    "sizeBytes": 1,
    "sha256": "9f2b5c1d7e3a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c"
  }),
});
const { data, error } = await response.json();
if (!response.ok) throw new Error(`${error.code}: ${error.message}`);
console.log(data);

import os
import uuid

import requests

response = requests.post(
    "https://app.getoatmilk.com/api/v1/accounting/documents.assets.prepare",
    headers={
        "Authorization": f"Bearer {os.environ['OATMILK_API_KEY']}",
        "Idempotency-Key": str(uuid.uuid4()),
    },
    json={
        "filename": "receipt.png",
        "mimeType": "image/png",
        "sizeBytes": 1,
        "sha256": "9f2b5c1d7e3a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c",
    },
    timeout=30,
)
payload = response.json()
if not response.ok:
    raise RuntimeError(f"{payload['error']['code']}: {payload['error']['message']}")
print(payload["data"])

Fields

Example

Try it