> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tai42.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Utilities

> Shared helpers and re-exported types the SDK exposes.

Shared helpers and re-exported types the SDK exposes.

## ApiClient

```ts theme={null}
type ApiClient = ReturnType<typeof createApiClient>
```

## SchemaEditor

```ts theme={null}
function SchemaEditor(props: SchemaEditorProps): ReactNode
```

**Props**

| Prop           | Type                                   | Description                                                                    |
| -------------- | -------------------------------------- | ------------------------------------------------------------------------------ |
| `description?` | `string`                               | —                                                                              |
| `disabled?`    | `boolean`                              | —                                                                              |
| `idPrefix?`    | `string`                               | —                                                                              |
| `label?`       | `string`                               | —                                                                              |
| `onChange`     | `(change: SchemaEditorChange) => void` | Fired on every edit with the parsed schema (or `null`) and its validity.       |
| `requireTitle` | `boolean`                              | When true, a top-level `"title"` is required (the `response_format` contract). |
| `value`        | `Record<string, unknown> \| null`      | The schema dict to seed the editor with, or `null` for an empty editor.        |

**Related:** [SchemaEditorProps](/reference/studio-sdk/utilities#schemaeditorprops)

## SchemaEditorChange

```ts theme={null}
interface SchemaEditorChange
```

What `SchemaEditor` reports up on every edit.

**Properties**

| Property | Type                              | Description                                                                             |
| -------- | --------------------------------- | --------------------------------------------------------------------------------------- |
| `schema` | `Record<string, unknown> \| null` | The authored schema dict when valid and non-empty; `null` when the editor is empty.     |
| `valid`  | `boolean`                         | False when the text is non-empty but unparseable or failing lint — gate submit on this. |

## SchemaEditorProps

```ts theme={null}
interface SchemaEditorProps
```

**Properties**

| Property       | Type                                   | Description                                                                    |
| -------------- | -------------------------------------- | ------------------------------------------------------------------------------ |
| `description?` | `string`                               | —                                                                              |
| `disabled?`    | `boolean`                              | —                                                                              |
| `idPrefix?`    | `string`                               | —                                                                              |
| `label?`       | `string`                               | —                                                                              |
| `onChange`     | `(change: SchemaEditorChange) => void` | Fired on every edit with the parsed schema (or `null`) and its validity.       |
| `requireTitle` | `boolean`                              | When true, a top-level `"title"` is required (the `response_format` contract). |
| `value`        | `Record<string, unknown> \| null`      | The schema dict to seed the editor with, or `null` for an empty editor.        |

**Related:** [SchemaEditorChange](/reference/studio-sdk/utilities#schemaeditorchange)

## SchemaLintResult

```ts theme={null}
interface SchemaLintResult
```

The parse/lint outcome for one editor text buffer.

**Properties**

| Property | Type                              | Description                                                                                                                                                                                                                                                                                                    |
| -------- | --------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `error`  | `string \| undefined`             | A loud, human-readable message when valid is false; else `undefined`.                                                                                                                                                                                                                                          |
| `schema` | `Record<string, unknown> \| null` | The parsed schema dict when the text is a syntactically valid JSON object, or `null` when the text is empty or does not parse. Carries the parsed object even when a lint (e.g. a missing `title`) fails, so the preview can still show the authored shape — the consumer gates on valid, never on this alone. |
| `valid`  | `boolean`                         | True when the text is empty or a valid schema. False when the text is non-empty but fails to parse or fails a structural lint — the consumer blocks submit.                                                                                                                                                    |

## comboElementNames

```ts theme={null}
function comboElementNames(
  combo: readonly (string | { config: Record<string, unknown>; name: string })[],
): string[]
```

Project a combo's elements to their bare extension names (drops any `config`).

**Parameters**

| Parameter | Type                                                                       | Default | Description |
| --------- | -------------------------------------------------------------------------- | ------- | ----------- |
| `combo`   | `readonly (string \| { config: Record<string, unknown>; name: string })[]` | —       | —           |

## downloadBlob

```ts theme={null}
function downloadBlob(blob: Blob, filename: string): void
```

Stream a `Blob` (an export- or content-route response) to the user as a file
download via a transient object URL. The object URL is revoked on the next tick —
revoking it synchronously can cancel the download before the browser commits it.

**Parameters**

| Parameter  | Type     | Default | Description |
| ---------- | -------- | ------- | ----------- |
| `blob`     | `Blob`   | —       | —           |
| `filename` | `string` | —       | —           |

## errorMessage

```ts theme={null}
function errorMessage(error: unknown): string
```

Normalize an unknown thrown/rejected value (a TanStack Query `error`, a
rejected mutation, a zod/`ApiError`) into a human-readable string for the loud
`ErrorState` / `Field` surfaces. This only turns a caught value into
displayable text — it never swallows the failure; the caller decides where to
show it, and the message is always shown, never blank.

**Parameters**

| Parameter | Type      | Default | Description |
| --------- | --------- | ------- | ----------- |
| `error`   | `unknown` | —       | —           |

## extensionElementName

```ts theme={null}
function extensionElementName(
  element: string | { config: Record<string, unknown>; name: string },
): string
```

The bare extension name of one combo element (drops any `config`).

**Parameters**

| Parameter | Type                                                          | Default | Description |
| --------- | ------------------------------------------------------------- | ------- | ----------- |
| `element` | `string \| { config: Record<string, unknown>; name: string }` | —       | —           |

## extensionsQueryKey

```ts theme={null}
const extensionsQueryKey: readonly ["extensions"]
```

The extension catalog (`GET /api/extensions`). The extensions feature keys its
read-only catalog on it; a tool's extension-combo save (in the tools feature)
creates or tears down branch tools, so it invalidates this key too — a
cross-feature reference that must resolve to one authoritative constant.

## lintSchemaText

```ts theme={null}
function lintSchemaText(text: string, requireTitle: boolean): SchemaLintResult
```

Parse and structurally lint a JSON-Schema editor buffer.

* Empty text is VALID (an unset, optional schema) with a `null` schema.
* Malformed JSON is INVALID; the parser message is surfaced verbatim.
* A top-level value that is not a JSON object (an array or a scalar) is INVALID.
* When `requireTitle`, a top-level string `"title"` is REQUIRED (the
  `response_format` contract the backend enforces); its absence is INVALID.

The parsed object is returned untouched — no key is normalized, reordered, or
dropped — so a schema carrying `$defs`/`anyOf` round-trips exactly.

**Parameters**

| Parameter      | Type      | Default | Description |
| -------------- | --------- | ------- | ----------- |
| `text`         | `string`  | —       | —           |
| `requireTitle` | `boolean` | —       | —           |

**Related:** [SchemaLintResult](/reference/studio-sdk/utilities#schemalintresult)

## subMcpKey

```ts theme={null}
const subMcpKey: readonly ["sub-mcp"]
```

The discovered sub-MCP mounts (`GET /api/sub-mcp`). The settings feature reads
this map (its scope mapper lists the mounts) while the manifest feature owns the
create/delete controls that mutate it; both must key and invalidate the exact
same tuple, so it lives here rather than as a literal duplicated across the two
features (which cannot import each other).

## toolsListKey

```ts theme={null}
const toolsListKey: readonly ["tools"]
```

The registered-tool master list (`GET /api/tools`).