# Start a catalog photo upload

> Reserves a photo for a catalog entry and returns a single-use upload URL (valid 2 hours).

`POST /v1/catalog/entities/{entityId}/images`

Reserves a photo for a catalog entry and returns a single-use upload URL (valid 2 hours). Then PUT the image's bytes to `upload.url` with exactly `upload.headers` — no Authorization header — and call POST /catalog/entities/{entityId}/images/{assetId}/complete to attach it. Up to 15 MB; PNG, JPEG, WebP, AVIF or GIF. bymundi stores its own re-encoded copy (WebP, at most 2000 px on the longest side, no EXIF).

**Permissions:** `catalog:write` · **Kind:** write · **Cost:** 1 unit · MCP tool [`start_catalog_image_upload`](https://api.bymundi.com/docs/mcp/tools/start_catalog_image_upload.md)

Cannot be undone.

## Path parameters

| Field | Type | Required | Description |
|---|---|---|---|
| `entityId` | uuid | yes |  |

## Body

| Field | Type | Required | Description |
|---|---|---|---|
| `mimeType` | "image/png" \| "image/jpeg" \| "image/webp" \| "image/avif" \| "image/gif" | yes | The image's type — only these are accepted. |
| `byteSize` | integer | yes | The file's size in bytes (at most 15 MB). 1–15728640 |

## Response `201`

| Field | Type | Required | Description |
|---|---|---|---|
| `object` | "catalog_image_upload" | yes |  |
| `entityId` | uuid | yes |  |
| `assetId` | uuid | yes |  |
| `upload` | object | yes |  |
| `upload.method` | "PUT" | yes |  |
| `upload.url` | uri | yes | Single-use: PUT the image's bytes here once. |
| `upload.headers` | object | yes | Send exactly these headers with the PUT. |
| `upload.expiresAt` | string | yes |  |

## Errors

Errors are [problem details](https://api.bymundi.com/docs/guides/errors.md). Besides the refusals described above, any call like this one can return:

- [`invalid_request`](https://api.bymundi.com/problems/invalid_request.md) — Invalid request
- [`unauthorized`](https://api.bymundi.com/problems/unauthorized.md) — Missing or invalid API key
- [`insufficient_scope`](https://api.bymundi.com/problems/insufficient_scope.md) — Missing permission
- [`rate_limited`](https://api.bymundi.com/problems/rate_limited.md) — Rate limit reached
- [`not_found`](https://api.bymundi.com/problems/not_found.md) — Not found
- [`idempotency_key_reused`](https://api.bymundi.com/problems/idempotency_key_reused.md) — Idempotency-Key reused
- [`request_in_progress`](https://api.bymundi.com/problems/request_in_progress.md) — Request in progress

## Examples

#### curl

```bash
curl -X POST https://api.bymundi.com/v1/catalog/entities/$ENTITY_ID/images \
  -H "Authorization: Bearer $BYMUNDI_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{"mimeType":"image/png","byteSize":1}'
```

#### JavaScript

```javascript
const res = await fetch(`https://api.bymundi.com/v1/catalog/entities/${entityId}/images`, {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.BYMUNDI_KEY}`,
    "Content-Type": "application/json",
    "Idempotency-Key": crypto.randomUUID(),
  },
  body: JSON.stringify({"mimeType":"image/png","byteSize":1}),
});
if (!res.ok) throw new Error((await res.json()).detail);
const data = await res.json();
```

#### Python

```python
import os, uuid, requests

res = requests.post(
    f"https://api.bymundi.com/v1/catalog/entities/{entityId}/images",
    headers={"Authorization": f"Bearer {os.environ['BYMUNDI_KEY']}", "Idempotency-Key": str(uuid.uuid4())},
    json={"mimeType":"image/png","byteSize":1},
)
res.raise_for_status()
data = res.json()
```