assistant-ui--assistant-ui/apps/docs/content/tap-docs/store/meta.mdx

---
title: Meta
description: Track scope origin with source and query.
---

Every scope accessor has two metadata properties: `source` and `query`. They describe where a scope comes from.

```tsx
aui.thread.source; // "root" | "parentScope" | null
aui.thread.query; // {} | { index: 0 } | null
```

## Root scopes

When you fill a scope directly via `useAui({ ... })`, it gets `source: "root"` and an empty `query`:

```tsx
const aui = useAui({ thread: ThreadResource() });

aui.thread.source; // "root"
aui.thread.query; // {}
```

This is the default — the scope was provided directly, not derived from another scope.

## Derived scopes

When a scope is created via `Derived`, its `source` points to the parent scope it was derived from, and `query` carries the lookup parameters:

```tsx
const aui = useAui({
  message: Derived({
    source: "thread",
    query: { index: 0 },
    get: (aui) => aui.thread().message({ index: 0 }),
  }),
});

aui.message.source; // "thread"
aui.message.query; // { index: 0 }
```

You can declare the expected meta shape in `ScopeRegistry`:

```ts
declare module "@assistant-ui/store" {
  interface ScopeRegistry {
    message: {
      methods: {
        getState: () => { role: string; content: string };
      };
      meta: { source: "thread"; query: { index: number } };
    };
  }
}
```

This makes the `source` and `query` types precise — TypeScript will enforce that any `Derived` providing the `message` scope uses the correct source and query shape.

## Unavailable scopes

When a scope hasn't been provided by any `AuiProvider` above the current component, its accessor has `source: null` and `query: null`:

```tsx
aui.message.source; // null — no message scope in context
aui.message.query; // null
```

This is how you check whether a scope is available.

## Summary

| `source` | Meaning |
| --- | --- |
| `"root"` | Scope was filled directly via `useAui({ ... })` |
| `"parentScope"` | Scope was derived from another scope via `Derived` |
| `null` | Scope is not available in the current context |