injectHostContext

injectHostContext(): HostContextSignals
createHostContextSignals(adaptor: Adaptor): HostContextSignals

injectHostContext() gives you one readonly signal for each key that the host exposes. The typed wrappers are all derived from it.

import { injectHostContext } from "ng-mcp-ui/web";

const host = injectHostContext();
host.theme();        // "light" | "dark"
host.toolOutput();   // Record<string, unknown> | null

Prefer the typed wrappers. Read this directly only when a key has no wrapper, or when you want several keys at once without several calls.

The keys

Key	Type	Wrapper
theme	Theme	injectLayout
maxHeight	number | undefined	injectLayout
safeArea	SafeArea	injectLayout
locale	string	injectUser
userAgent	UserAgent	injectUser
displayMode	DisplayMode	injectDisplayMode
display	{ mode, params? }	injectRequestModal
toolInput	Record<string, unknown> | null	injectToolInfo
toolOutput	Record<string, unknown> | null	injectToolInfo
toolResponseMetadata	Record<string, unknown> | null	injectToolInfo
viewState	Record<string, unknown> | null	injectViewState

destroy

The returned object also has a destroy() method. It removes each host subscription.

Inside an injection context the cleanup runs for you through DestroyRef. Call destroy() yourself only when you used createHostContextSignals.

createHostContextSignals

The non-DI form. Pass an adaptor directly.

const signals = createHostContextSignals(adaptor);
// …
signals.destroy();

Use it in code that already holds an adaptor, for example a plain unit test with a MockAdaptor.

Host support

Each key works on the two host runtimes. The values differ, because each adaptor maps them from a different host API.

Related

• Host bridge and adaptors
• Host support