# TextAdapter # Interface: TextAdapter\ Defined in: [packages/ai/src/activities/chat/adapter.ts:67](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L67) Text adapter interface with pre-resolved generics. An adapter is created by a provider function: `provider('model')` → `adapter` All type resolution happens at the provider call site, not in this interface. Generic parameters: - TModel: The specific model name (e.g., 'gpt-4o') - TProviderOptions: Provider-specific options for this model (already resolved) - TInputModalities: Supported input modalities for this model (already resolved) - TMessageMetadata: Metadata types for content parts (already resolved) - TToolCapabilities: Tuple of tool-kind strings supported by this model, resolved from `supports.tools` - TToolCallMetadata: Metadata type that round-trips with tool calls (e.g. Gemini's `thoughtSignature`) - TSystemPromptMetadata: Provider-typed metadata accepted on each `systemPrompts[i]` entry (e.g. Anthropic `cache_control`). Defaults to `never` — adapters without per-prompt metadata reject the `metadata` field at the call site. ## Type Parameters ### TModel `TModel` *extends* `string` ### TProviderOptions `TProviderOptions` *extends* `Record`\<`string`, `any`\> ### TInputModalities `TInputModalities` *extends* `ReadonlyArray`\<[`Modality`](../type-aliases/Modality.md)\> ### TMessageMetadataByModality `TMessageMetadataByModality` *extends* [`DefaultMessageMetadataByModality`](DefaultMessageMetadataByModality.md) ### TToolCapabilities `TToolCapabilities` *extends* `ReadonlyArray`\<`string`\> = `ReadonlyArray`\<`string`\> ### TToolCallMetadata `TToolCallMetadata` = `unknown` ### TSystemPromptMetadata `TSystemPromptMetadata` = `never` ## Properties ### ~types ```ts ~types: object; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:95](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L95) **`Internal`** Type-only properties for inference. Not assigned at runtime. #### inputModalities ```ts inputModalities: TInputModalities; ``` #### messageMetadataByModality ```ts messageMetadataByModality: TMessageMetadataByModality; ``` #### providerOptions ```ts providerOptions: TProviderOptions; ``` #### systemPromptMetadata ```ts systemPromptMetadata: TSystemPromptMetadata; ``` #### toolCallMetadata ```ts toolCallMetadata: TToolCallMetadata; ``` #### toolCapabilities ```ts toolCapabilities: TToolCapabilities; ``` *** ### chatStream ```ts chatStream: (options) => AsyncIterable; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:107](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L107) Stream text completions from the model #### Parameters ##### options [`TextOptions`](TextOptions.md)\<`TProviderOptions`\> #### Returns `AsyncIterable`\<[`AdapterYieldChunk`](../type-aliases/AdapterYieldChunk.md)\> *** ### combinedStructuredOutputSource? ```ts optional combinedStructuredOutputSource?: (modelOptions?) => "text" | "event"; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:174](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L174) Where native-combined structured output is taken from. - `'text'` (default when omitted): the agent loop's accumulated assistant text is schema JSON. The engine parses it after the loop. HTTP adapters use this. - `'event'`: the adapter emits `structured-output.complete` during `chatStream`. The engine must not parse accumulated prose. Harness adapters use this. #### Parameters ##### modelOptions? `TProviderOptions` #### Returns `"text"` \| `"event"` *** ### kind ```ts readonly kind: "text"; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:77](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L77) Discriminator for adapter kind *** ### model ```ts readonly model: TModel; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:81](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L81) The model this adapter is configured for *** ### name ```ts readonly name: string; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:79](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L79) Provider name identifier (e.g., 'openai', 'anthropic') *** ### requires? ```ts readonly optional requires?: readonly CapabilityHandle[]; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:90](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L90) Capabilities this adapter requires at runtime. `chat()` validates that the configured middleware provides each one. Model adapters omit this; harness adapters (e.g. a future `claudeCode()`) declare e.g. `[sandboxCapability]`. Runtime access to capabilities from inside the adapter is not yet wired — this is the declaration/validation surface only. *** ### structuredOutput ```ts structuredOutput: (options) => Promise>; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:119](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L119) Generate structured output using the provider's native structured output API. This method uses stream: false and sends the JSON schema to the provider to ensure the response conforms to the expected structure. #### Parameters ##### options `StructuredOutputOptions`\<`TProviderOptions`\> Structured output options containing chat options and JSON schema #### Returns `Promise`\<`StructuredOutputResult`\<`unknown`\>\> Promise with the raw data (validation is done in the chat function) *** ### structuredOutputStream? ```ts optional structuredOutputStream?: (options) => AsyncIterable; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:137](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L137) Stream structured output using the provider's native streaming structured output API (stream + response_format json_schema in a single request). Optional — adapters without native streaming JSON omit this method and the activity layer synthesizes a stream around the non-streaming `structuredOutput` call. Implementations must emit standard AG-UI lifecycle events (RUN_STARTED, TEXT_MESSAGE_*, RUN_FINISHED) carrying raw JSON text deltas, plus a final `CUSTOM` event named `structured-output.complete` whose `value` is `{ object, raw, reasoning? }`. Events must be timestamped when emitted so their timestamps follow stream order. #### Parameters ##### options `StructuredOutputOptions`\<`TProviderOptions`\> #### Returns `AsyncIterable`\<[`AdapterYieldChunk`](../type-aliases/AdapterYieldChunk.md)\> *** ### supportsCombinedToolsAndSchema? ```ts optional supportsCombinedToolsAndSchema?: (modelOptions?) => boolean; ``` Defined in: [packages/ai/src/activities/chat/adapter.ts:160](https://github.com/TanStack/ai/blob/main/packages/ai/src/activities/chat/adapter.ts#L160) Declares whether the adapter supports combining `tools` and a schema-constrained final answer in a single streaming request. When `true`, the engine wires `outputSchema` into the regular `chatStream()` call and skips the separate `runStructuredFinalization` round-trip. The model's natural final turn carries the schema-constrained JSON text and the engine harvests it from the agent loop's accumulated content. When `false`, `undefined`, or the method is omitted, the engine runs the agent loop without `outputSchema` and then issues a separate `structuredOutput` / `structuredOutputStream` call against the JSON schema for finalization (the legacy path). The method receives the per-call `modelOptions` so providers whose support depends on the resolved upstream model (e.g. OpenRouter) can answer per-request. Most adapters can return a constant. #### Parameters ##### modelOptions? `TProviderOptions` #### Returns `boolean`