@ai-sdk/react 2.0.0: useChat migration

@ai-sdk/react 2.0.0 removes useAssistant, replaces Message and CreateMessage with UIMessage and CreateUIMessage, and reshapes useChat and useCompletion. A component that imports these from @ai-sdk/react, or reads a removed member off what useChat returns, stops type-checking. The AI SDK 5 migration guide is the source for the replacements below.

What changed

Removed exports. useAssistant and UseAssistantHelpers are no longer exported, and the package has no hook in their place. Message and CreateMessage give way to UIMessage and CreateUIMessage, which hold content in parts rather than a content string.
useChat return members. input, setInput, handleInputChange and handleSubmit are gone. append becomes sendMessage, reload becomes regenerate, isLoading becomes status, and experimental_resume becomes resumeStream. data, setData and metadata are no longer returned.
useChat options. api, credentials, headers, body, fetch, streamProtocol and experimental_prepareRequestBody move to a transport, built with DefaultChatTransport. initialMessages is now messages. initialInput, maxSteps, keepLastMessageOnError, sendExtraMessageFields, key and onResponse are removed.
useCompletion. data and onResponse are removed. Its input, handleInputChange, handleSubmit and isLoading are unchanged, so leave those reads alone.

Before and after

The one deterministic patch renames a returned member:

// before
const resume = () => chat.experimental_resume();

// after
const resume = () => chat.resumeStream();

The other rewrites are assisted. append is one where the shape change is the point:

// before
const ask = (text: string) => chat.append({ role: 'user', content: text });

// after
const ask = (text: string) => chat.sendMessage({ text });

The remaining assisted patches cover input state, transport options, messages, status and the removed options.

Migration guidance and its limits

Run emendant scan to list the affected sites, then emendant fix. The experimental_resume rename is a deterministic patch and needs no model provider. The other thirteen findings have assisted patches, and emendant fix writes them only when you name a model provider. Each patch is checked with your typecheck and your tests.

Some edits reach past the component. Moving off data needs the server route to write data parts, and moving off useAssistant means moving the route off the Assistants API. That removal has no direct replacement; review the surrounding code. A patch may not be available for these, or for an onResponse that did more than inspect the status or headers of the response.

Stored messages need attention too. Messages saved in the earlier shape must be converted to parts before they are passed as messages. Code that awaited append or reload for the response must read the last message from messages instead.

No finding in this release is report only. A clean scan covers imports from @ai-sdk/react and the useChat and useCompletion uses described above. It does not check your server routes, your stored messages or your other AI SDK packages.

What Emendant detects, fixes and verifies

14 changes in @ai-sdk/react 2.0.0. 1 automatic fixes, 13 fixes requiring a model provider you choose, 0 report only. Each patch states which checks passed. Understand patch evidence.

Change	Severity	Detects	Fix	Verified by
useAssistant was removed `ai-sdk-react-npm-2.0.0-use-assistant-removed` `error TS2305: Module '"@ai-sdk/react"' has no exported member 'useAssistant'.` `error TS2305: Module '"@ai-sdk/react"' has no exported member 'UseAssistantHelpers'.`	Breaking	`useAssistant` imported from `@ai-sdk/react` `UseAssistantHelpers` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
Message and CreateMessage are no longer exported, in favour of UIMessage and CreateUIMessage `ai-sdk-react-npm-2.0.0-message-types-removed` `error TS2724: '"@ai-sdk/react"' has no exported member named 'CreateMessage'. Did you mean 'CreateUIMessage'?` `error TS2724: '"@ai-sdk/react"' has no exported member named 'Message'. Did you mean 'UIMessage'?`	Breaking	`Message` imported from `@ai-sdk/react` `CreateMessage` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
useChat no longer manages the input `ai-sdk-react-npm-2.0.0-use-chat-input-removed` `error TS2339: Property 'handleSubmit' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.` `error TS2339: Property 'input' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.` `error TS2339: Property 'handleInputChange' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.` `error TS2339: Property 'setInput' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.`	Breaking	`.input` read on what `useChat` imported from `@ai-sdk/react` returns `.setInput` read on what `useChat` imported from `@ai-sdk/react` returns `.handleInputChange` read on what `useChat` imported from `@ai-sdk/react` returns `.handleSubmit` read on what `useChat` imported from `@ai-sdk/react` returns the `initialInput` key in the object passed to `useChat` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
useChat's append was removed in favour of sendMessage `ai-sdk-react-npm-2.0.0-use-chat-append-removed` `error TS2339: Property 'append' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.`	Breaking	`.append` read on what `useChat` imported from `@ai-sdk/react` returns	Patch, only when you name a model provider	Your typecheck and tests
useChat's reload was removed in favour of regenerate `ai-sdk-react-npm-2.0.0-use-chat-reload-removed` `error TS2339: Property 'reload' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.`	Breaking	`.reload` read on what `useChat` imported from `@ai-sdk/react` returns	Patch, only when you name a model provider	Your typecheck and tests
useChat's experimental_resume is now resumeStream `ai-sdk-react-npm-2.0.0-use-chat-experimental-resume-renamed` `error TS2339: Property 'experimental_resume' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.`	Breaking	`.experimental_resume` read on what `useChat` imported from `@ai-sdk/react` returns	Patch, written by the rename-property transform	Your typecheck and tests
useChat's isLoading was removed in favour of status `ai-sdk-react-npm-2.0.0-use-chat-is-loading-removed` `error TS2339: Property 'isLoading' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.`	Breaking	`.isLoading` read on what `useChat` imported from `@ai-sdk/react` returns	Patch, only when you name a model provider	Your typecheck and tests
useChat no longer returns data, setData or metadata `ai-sdk-react-npm-2.0.0-use-chat-data-removed` `error TS2339: Property 'data' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.` `error TS2339: Property 'metadata' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.` `error TS2339: Property 'setData' does not exist on type 'UseChatHelpers<UIMessage<unknown, UIDataTypes, UITools>>'.`	Breaking	`.data` read on what `useChat` imported from `@ai-sdk/react` returns `.setData` read on what `useChat` imported from `@ai-sdk/react` returns `.metadata` read on what `useChat` imported from `@ai-sdk/react` returns	Patch, only when you name a model provider	Your typecheck and tests
useChat's request options moved to a transport `ai-sdk-react-npm-2.0.0-use-chat-request-options-moved-to-transport` `error TS2353: Object literal may only specify known properties, and 'api' does not exist in type 'UseChatOptions<UIMessage<unknown, UIDataTypes, UITools>>'.` `error TS7031: Binding element 'messages' implicitly has an 'any' type.`	Breaking	the `api` key in the object passed to `useChat` imported from `@ai-sdk/react` the `credentials` key in the object passed to `useChat` imported from `@ai-sdk/react` the `headers` key in the object passed to `useChat` imported from `@ai-sdk/react` the `body` key in the object passed to `useChat` imported from `@ai-sdk/react` the `fetch` key in the object passed to `useChat` imported from `@ai-sdk/react` the `streamProtocol` key in the object passed to `useChat` imported from `@ai-sdk/react` the `experimental_prepareRequestBody` key in the object passed to `useChat` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
useChat's initialMessages is now messages `ai-sdk-react-npm-2.0.0-use-chat-initial-messages-renamed`	Breaking	the `initialMessages` key in the object passed to `useChat` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
useChat's maxSteps was removed `ai-sdk-react-npm-2.0.0-use-chat-max-steps-removed`	Breaking	the `maxSteps` key in the object passed to `useChat` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
useChat's keepLastMessageOnError, sendExtraMessageFields, key and onResponse were removed `ai-sdk-react-npm-2.0.0-use-chat-options-removed` `error TS7006: Parameter 'response' implicitly has an 'any' type.`	Breaking	the `keepLastMessageOnError` key in the object passed to `useChat` imported from `@ai-sdk/react` the `sendExtraMessageFields` key in the object passed to `useChat` imported from `@ai-sdk/react` the `key` key in the object passed to `useChat` imported from `@ai-sdk/react` the `onResponse` key in the object passed to `useChat` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests
useCompletion no longer returns data `ai-sdk-react-npm-2.0.0-use-completion-data-removed` `error TS2339: Property 'data' does not exist on type 'UseCompletionHelpers'.`	Breaking	`.data` read on what `useCompletion` imported from `@ai-sdk/react` returns	Patch, only when you name a model provider	Your typecheck and tests
useCompletion's onResponse was removed `ai-sdk-react-npm-2.0.0-use-completion-on-response-removed` `error TS2353: Object literal may only specify known properties, and 'onResponse' does not exist in type 'UseCompletionOptions & { experimental_throttle?: number \| undefined; }'.` `error TS7006: Parameter 'response' implicitly has an 'any' type.`	Breaking	the `onResponse` key in the object passed to `useCompletion` imported from `@ai-sdk/react`	Patch, only when you name a model provider	Your typecheck and tests

emendant explain <change-id> prints any row's entry, guidance and sources at the terminal.

The error TS lines are what TypeScript 5.9.3 printed when code that compiled against @ai-sdk/react 1.2.12 was compiled against 2.0.0. A row without one is a change the compiler does not report, such as a deprecation or a change in behaviour.

Coverage

Requires emendant@0.3.0 or later. Run emendant feed update to get the latest coverage.

Coverage details

Snapshot: 2026-10-21.3, sequence 53, signed 21 October 2026
Feed entry: feed/npm/@ai-sdk/react/2.0.0.json

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Primary sources

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Then npx emendant fix writes the patches the table says exist. The getting started guide covers the flags and the patch grades.

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