ChatMiddlewareContext

Defined in: packages/ai/src/activities/chat/middleware/types.ts:194

Stable context object passed to all middleware hooks. Created once per chat() invocation and shared across all hooks.

Type Parameters#

TContext#

TContext = unknown

Properties#

abort#

abort: (reason?) => void;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:240

Abort the chat run with a reason

Parameters#

reason?#

string

Returns#

void

accumulatedContent#

accumulatedContent: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:307

Accumulated text content for the current iteration

activities?#

optional activities?: readonly ActivityRecord[];

Defined in: packages/ai/src/activities/chat/middleware/types.ts:318

Frontend-only AG-UI activity sidecar. Never model input. Persistence writes this when an ActivityStore is configured. Optional so code that builds its own context keeps working; the engine always sets it.

activity#

activity: "chat";

Defined in: packages/ai/src/activities/chat/middleware/types.ts:274

Which activity this context describes — always 'chat'. Present so the chat context structurally satisfies the base GenerationMiddlewareContext, letting an observe-only middleware authored against the base (e.g. otelMiddleware) run on both chat and media activities.

callMetadata#

callMetadata: Readonly<TanStackMessageMetadata>;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:236

The metadata.tanstack of the current model call: source, stop reason, response id, and so on. It changes as chunks arrive. Each assistant message of the call gets a copy of it.

capabilities#

capabilities: CapabilityRegistry;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:327

Capability bookkeeping for this request. Populated by middleware setup hooks (via provide accessors) and read by later middleware (via get accessors). Prefer the accessors returned by createCapability over using this directly. Orthogonal to context (the user runtime context).

childResumeIds?#

optional childResumeIds?: ReadonlySet<string>;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:218

Interrupt ids in resume that a subagent tool call of this run answers. This run does not answer them itself. They come from the subagent cards in the messages the client sent. undefined when no child is resumed, and for a router turn.

chunkIndex#

chunkIndex: number;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:230

Running count of chunks yielded so far

context#

context: TContext;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:258

Runtime context provided by chat() options

createId#

createId: (prefix) => string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:320

Generate a unique ID with the given prefix

Parameters#

prefix#

string

Returns#

string

currentMessageId#

currentMessageId: string | null;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:305

Current assistant message ID (changes per iteration)

defer#

defer: (promise) => void;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:264

Defer a non-blocking side-effect promise. Deferred promises do not block streaming and are awaited after the terminal hook (onFinish/onAbort/onError).

Parameters#

promise#

Promise<unknown>

Returns#

void

emitCustomEvent#

emitCustomEvent: (name, value, options?) => void;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:252

Push a CUSTOM chunk onto the chat stream immediately. The engine yields it as soon as it can (including while onConfig is still awaiting work such as a summarize call). Durability then flushes the event on its own, unless you pass { batch: true }.

Parameters#

name#

string

value#

Record<string, any>

options?#

EmitCustomEventOptions

Returns#

void

get#

get: <TValue>(capability) => TValue;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:332

Read a provided capability by its handle. Equivalent to the handle's own get accessor (getX(ctx)); throws if the capability was never provided.

Type Parameters#

TValue#

TValue

Parameters#

capability#

Capability<TValue>

Returns#

TValue

getOptional#

getOptional: <TValue>(capability) => TValue | undefined;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:337

Read a capability by its handle, returning undefined if it was never provided (never throws).

Type Parameters#

TValue#

TValue

Parameters#

capability#

Capability<TValue>

Returns#

TValue | undefined

hasTools#

hasTools: boolean;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:300

Whether tools are configured

iteration#

iteration: number;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:228

Current agent loop iteration (0-indexed)

messageCount#

messageCount: number;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:298

Number of messages at the start of the request

messages#

messages: readonly ModelMessage<
  | string
  | ContentPart<unknown, unknown, unknown, unknown, unknown>[]
  | null>[];

Defined in: packages/ai/src/activities/chat/middleware/types.ts:312

Current messages array (read-only view)

model#

model: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:278

Model identifier (e.g., 'gpt-5.5')

modelOptions?#

optional modelOptions?: Record<string, unknown>;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:293

Provider-specific model options

options?#

optional options?: Record<string, unknown>;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:291

Flattened generation options (metadata)

parentRunId?#

optional parentRunId?: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:202

Interrupted or parent run correlated with this continuation.

parentSubagentRunId?#

optional parentSubagentRunId?: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:211

The subagentRunId of the child that started this one, for a nested child.

phase#

phase: ChatMiddlewarePhase;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:226

Current lifecycle phase

provide#

provide: <TValue>(capability, value) => void;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:342

Provide a capability value. Equivalent to the handle's own provide accessor (provideX(ctx, value)). Typically called from setup.

Type Parameters#

TValue#

TValue

Parameters#

capability#

Capability<TValue>

value#

TValue

Returns#

void

provider#

provider: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:276

Provider name (e.g., 'openai', 'anthropic')

requestId#

requestId: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:196

Unique identifier for this chat request

retry#

retry: () => void;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:245

Call the model again. Works only in onModelError, and throws in any other hook. onConfig runs again before the new call.

Returns#

void

runId#

runId: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:200

AG-UI run identifier for correlating client and server events

signal?#

optional signal?: AbortSignal;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:238

Abort signal from the chat request

source#

source: "server" | "client";

Defined in: packages/ai/src/activities/chat/middleware/types.ts:280

Source of the chat invocation — always 'server' for server-side chat

streamId#

streamId: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:198

Unique identifier for this stream

streaming#

streaming: boolean;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:282

Whether the chat is streaming

subagentName?#

optional subagentName?: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:209

The agent name when this run is a subagent.

subagentRunId?#

optional subagentRunId?: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:207

Set when this run is a subagent. The id on the child's SUBAGENT_STARTED and on every chunk it streams. Absent on a top-level run.

systemPrompts#

systemPrompts: SystemPrompt[];

Defined in: packages/ai/src/activities/chat/middleware/types.ts:287

System prompts configured for this chat

threadId#

threadId: string;

Defined in: packages/ai/src/activities/chat/middleware/types.ts:224

AG-UI thread identifier — a stable per-conversation ID used to correlate client and server devtools events. It is the caller's threadId.

toolNames?#

optional toolNames?: string[];

Defined in: packages/ai/src/activities/chat/middleware/types.ts:289

Names of configured tools, if any