refactor: change CustomEvent property from 'data' to 'value' for AG-UI

.changeset/wicked-humans-shop.md

@@ -0,0 +1,6 @@
+---
+'@tanstack/ai-client': patch
+'@tanstack/ai': patch
+---
+
+Refactor CustomEvent property from 'data' to 'value' for AG-UI compliance

packages/python/tanstack-ai/src/tanstack_ai/chat.py

@@ -386,7 +386,7 @@ async def _emit_approval_requests(
                 "timestamp": int(time.time() * 1000),
                 "model": finish_event.get("model"),
                 "name": "approval-requested",
-                "data": {
+                "value": {
                     "toolCallId": approval.tool_call_id,
                     "toolName": approval.tool_name,
                     "input": approval.input,
@@ -410,7 +410,7 @@ async def _emit_client_tool_inputs(
                 "timestamp": int(time.time() * 1000),
                 "model": finish_event.get("model"),
                 "name": "tool-input-available",
-                "data": {
+                "value": {
                     "toolCallId": client_tool.tool_call_id,
                     "toolName": client_tool.tool_name,
                     "input": client_tool.input,

packages/python/tanstack-ai/src/tanstack_ai/types.py

@@ -284,7 +284,7 @@ class CustomEvent(TypedDict, total=False):
     timestamp: int
     model: Optional[str]
     name: str
-    data: Optional[Any]
+    value: Optional[Any]
 
 
 # Union of all AG-UI events

packages/typescript/ai/src/activities/chat/index.ts

@@ -842,7 +842,7 @@ class TextEngine<
         timestamp: Date.now(),
         model: finishEvent.model,
         name: 'approval-requested',
-        data: {
+        value: {
           toolCallId: approval.toolCallId,
           toolName: approval.toolName,
           input: approval.input,
@@ -879,7 +879,7 @@ class TextEngine<
         timestamp: Date.now(),
         model: finishEvent.model,
         name: 'tool-input-available',
-        data: {
+        value: {
           toolCallId: clientTool.toolCallId,
           toolName: clientTool.toolName,
           input: clientTool.input,
@@ -1094,14 +1094,14 @@ class TextEngine<
 
   private createCustomEventChunk(
     eventName: string,
-    data: Record<string, any>,
+    value: Record<string, any>,
   ): CustomEvent {
     return {
       type: 'CUSTOM',
       timestamp: Date.now(),
       model: this.params.model,
       name: eventName,
-      data,
+      value,
     }
   }
 

packages/typescript/ai/src/activities/chat/stream/processor.ts

@@ -814,8 +814,8 @@ export class StreamProcessor {
     chunk: Extract<StreamChunk, { type: 'CUSTOM' }>,
   ): void {
     // Handle client tool input availability - trigger client-side execution
-    if (chunk.name === 'tool-input-available' && chunk.data) {
-      const { toolCallId, toolName, input } = chunk.data as {
+    if (chunk.name === 'tool-input-available' && chunk.value) {
+      const { toolCallId, toolName, input } = chunk.value as {
         toolCallId: string
         toolName: string
         input: any
@@ -832,8 +832,8 @@ export class StreamProcessor {
     }
 
     // Handle approval requests
-    if (chunk.name === 'approval-requested' && chunk.data) {
-      const { toolCallId, toolName, input, approval } = chunk.data as {
+    if (chunk.name === 'approval-requested' && chunk.value) {
+      const { toolCallId, toolName, input, approval } = chunk.value as {
         toolCallId: string
         toolName: string
         input: any
@@ -863,8 +863,8 @@ export class StreamProcessor {
     }
 
     // Forward all other custom events to the callback
-    this.events.onCustomEvent?.(chunk.name, chunk.data, {
-      toolCallId: (chunk.data as any)?.toolCallId,
+    this.events.onCustomEvent?.(chunk.name, chunk.value, {
+      toolCallId: (chunk.value as any)?.toolCallId,
     })
   }
 

packages/typescript/ai/src/types.ts

@@ -922,8 +922,8 @@ export interface CustomEvent extends BaseAGUIEvent {
   type: 'CUSTOM'
   /** Custom event name */
   name: string
-  /** Custom event data */
-  data?: unknown
+  /** Custom event value */
+  value?: unknown
 }
 
 /**