AG-UI Support

.changeset/ag-ui-events.md

@@ -0,0 +1,17 @@
+---
+'@tanstack/ai': minor
+'@tanstack/ai-openai': minor
+'@tanstack/ai-anthropic': minor
+'@tanstack/ai-gemini': minor
+'@tanstack/ai-ollama': minor
+---
+
+feat: Add AG-UI protocol events to streaming system
+
+All text adapters now emit AG-UI protocol events only:
+
+- `RUN_STARTED` / `RUN_FINISHED` - Run lifecycle events
+- `TEXT_MESSAGE_START` / `TEXT_MESSAGE_CONTENT` / `TEXT_MESSAGE_END` - Text message streaming
+- `TOOL_CALL_START` / `TOOL_CALL_ARGS` / `TOOL_CALL_END` - Tool call streaming
+
+Only AG-UI event types are supported; previous legacy chunk formats (`content`, `tool_call`, `done`, etc.) are no longer accepted.

docs/guides/streaming.md

@@ -63,30 +63,33 @@ messages.forEach((message) => {
 });
 ```
 
-## Stream Chunks
+## Stream Events (AG-UI Protocol)
 
-Stream chunks contain different types of data:
+TanStack AI implements the [AG-UI Protocol](https://docs.ag-ui.com/introduction) for streaming. Stream events contain different types of data:
 
-- **Content chunks** - Text content being generated
-- **Thinking chunks** - Model's internal reasoning process (when supported)
-- **Tool call chunks** - When the model calls a tool
-- **Tool result chunks** - Results from tool execution
-- **Done chunks** - Stream completion
+### AG-UI Events
+
+- **RUN_STARTED** - Emitted when a run begins
+- **TEXT_MESSAGE_START/CONTENT/END** - Text content streaming lifecycle
+- **TOOL_CALL_START/ARGS/END** - Tool invocation lifecycle
+- **STEP_STARTED/STEP_FINISHED** - Thinking/reasoning steps
+- **RUN_FINISHED** - Run completion with finish reason and usage
+- **RUN_ERROR** - Error occurred during the run
 
 ### Thinking Chunks
 
-Thinking chunks represent the model's reasoning process. They stream separately from the final response text:
+Thinking/reasoning is represented by AG-UI events `STEP_STARTED` and `STEP_FINISHED`. They stream separately from the final response text:
 
 ```typescript
 for await (const chunk of stream) {
-  if (chunk.type === "thinking") {
+  if (chunk.type === "STEP_FINISHED") {
     console.log("Thinking:", chunk.content); // Accumulated thinking content
     console.log("Delta:", chunk.delta); // Incremental thinking token
   }
 }
 ```
 
-Thinking chunks are automatically converted to `ThinkingPart` in `UIMessage` objects. They are UI-only and excluded from messages sent back to the model.
+Thinking content is automatically converted to `ThinkingPart` in `UIMessage` objects. It is UI-only and excluded from messages sent back to the model.
 
 ## Connection Adapters