Message Layers

Four level message architecture summary

• UI messages: Contain data parts, shaped for UI rendering (packages/ai/src/ui/ui-messages.ts)
• Model messages: Abstracted, user-friendly version for good DX, used in generate/stream calls (packages/provider-utils/src/types/model-message.ts)
• Language model messages: Standardized spec, intended to be stable (packages/provider/src/language-model/v4/language-model-v4-prompt.ts)
• Provider-specific messages: Final conversion for specific API requirements (see e.g. getArgs() and doGenerate() method of OpenAIResponsesLanguageModel