uiMessageToModelMessages

function uiMessageToModelMessages(uiMessage): ModelMessage<
  | string
  | ContentPart<unknown, unknown, unknown, unknown, unknown>[]
  | null>[];

Defined in: packages/ai/src/activities/chat/messages.ts:715

Convert a UIMessage to ModelMessage(s)

Walks the parts array IN ORDER to preserve the interleaving of text, tool calls, and tool results. This is critical for multi-round tool flows where the model generates text, calls a tool, gets the result, then generates more text and calls another tool.

The output preserves the sequential structure: text1 → toolCall1 → toolResult1 → text2 → toolCall2 → toolResult2 becomes: assistant: {content: "text1", toolCalls: [toolCall1]} tool: toolResult1 assistant: {content: "text2", toolCalls: [toolCall2]} tool: toolResult2