runtime

State management and thread/message access layer for assistant-ui chat applications. Always consult assistant-ui.com/llms.txt for latest API. "Cannot read property of undefined" State not updating Messages array empty - Provides three runtime types: AssistantRuntime for overall state, ThreadRuntime for current conversation, and ThreadListRuntime for managing multiple threads - Access state via useAuiState selectors and perform operations through useAui() API (append messages, cancel runs, edit/reload messages, query capabilities) - Emit and listen to lifecycle events: thread.runStart , thread.runEnd , composer.send , and thread.modelContextUpdate - Hierarchical runtime structure supports per-message and per-content-part operations, with built-in capability detection for cancel, edit, reload, copy, speak, and attachments - ./references/local-runtime.md -- useLocalRuntime deep dive - ./references/external-store.md -- useExternalStoreRuntime deep dive - ./references/thread-list.md -- Thread list management - ./references/state-hooks.md -- State access hooks - ./references/types.md -- Type definitions - Ensure hooks are called inside AssistantRuntimeProvider - Use selectors with useAuiState to prevent unnecessary re-renders - Check runtime is configured - Verify API response format