---
title: "What a schema change would break"
description: "List permission rules, saved views, pages, and other fields that read the fields or tables you propose to remove."
canonical: "https://grid82.com/docs/builder-api/schema/impact"
updated: "2026-11-13"
---

# What a schema change would break

`POST https://studio.grid82.app/v1/apps/{appId}/schema/impact`

List permission rules, saved views, pages, and other fields that read the fields or tables you propose to remove.

Returns the same list that causes `fields.delete` and `tables.delete` to be refused until you send `acknowledge=true`. Matches pages by the names in their last build; references use IDs, so renaming breaks nothing and returns no results. Advisory only; changes nothing.

Requires the `schema:read` scope. Operation `schema.impact`. MCP tool `schema_impact`. CLI: `grid82 schema impact` (`npx grid82`).

## Path parameters

| Name    | Type   | Required | Description |
| ------- | ------ | -------- | ----------- |
| `appId` | string | yes      |             |

## Headers

| Name              | Type   | Required | Description                                                                                                                                                                                                                                                        |
| ----------------- | ------ | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `Idempotency-Key` | string | no       | Any unique string. Sending the same key with the same request again returns the first response (marked `Idempotency-Replayed: true`) instead of running it twice. Reusing it for a different request is refused with 409. Kept for 24 hours. Up to 255 characters. |

## Request body

| Field     | Type      | Required | Description   |
| --------- | --------- | -------- | ------------- |
| `drops`   | object\[] | no       | Default `[]`. |
| `renames` | object\[] | no       | Default `[]`. |

**Authorizations**

- `Authorization` (bearer, in header, required)

## Response

**200**: Success

- `data` (`object`, required)
- `data.pages` (`object[]`, required)
- `data.pages.pageId` (`string`, required)
- `data.pages.name` (`string`, required)
- `data.pages.reads` (`string[]`, required)
- `data.pages.repairable` (`boolean`, required)
- `data.views` (`object[]`, required)
- `data.views.viewId` (`string`, required)
- `data.views.name` (`string`, required)
- `data.views.reads` (`string[]`, required)
- `data.rules` (`object[]`, required)
- `data.rules.ruleId` (`string`, required)
- `data.rules.name` (`string`)
- `data.rules.reads` (`string[]`, required)
- `data.fields` (`object[]`)
- `data.fields.fieldId` (`string`, required)
- `data.fields.name` (`string`, required)
- `data.fields.reads` (`string[]`, required)

```json
{
  "data": {
    "pages": [
      {
        "pageId": "<string>",
        "name": "<string>",
        "reads": [
          "<string>"
        ],
        "repairable": true
      }
    ],
    "views": [
      {
        "viewId": "<string>",
        "name": "<string>",
        "reads": [
          "<string>"
        ]
      }
    ],
    "rules": [
      {
        "ruleId": "<string>",
        "name": "<string>",
        "reads": [
          "<string>"
        ]
      }
    ],
    "fields": [
      {
        "fieldId": "<string>",
        "name": "<string>",
        "reads": [
          "<string>"
        ]
      }
    ]
  }
}
```

**4XX**: Refused

- `error` (`object`, required)
- `error.code` (`enum<string>`, required, one of: `not_found, forbidden, unauthenticated, validation_failed, conflict, rate_limited, payment_required, not_implemented, internal`)
- `error.message` (`string`, required)
- `error.details` (`Record<string, unknown>`)

```json
{
  "error": {
    "code": "not_found",
    "message": "<string>",
    "details": {}
  }
}
```

**Example request**

```bash
curl --request POST \
  --url 'https://studio.grid82.app/v1/apps/<appId>/schema/impact' \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "drops": [],
  "renames": []
}'
```