fix(core): remove per-delta tracing overhead

Co-authored-by: Hona <10430890+Hona@users.noreply.github.com>

packages/ai/src/protocols/anthropic-messages.ts

@@ -864,7 +864,7 @@ const onContentBlockStart = (state: ParserState, event: AnthropicEvent): StepRes
   return [{ ...state, lifecycle: Lifecycle.stepStart(state.lifecycle, events) }, [...events, result]]
 }
 
-const onContentBlockDelta = Effect.fn("AnthropicMessages.onContentBlockDelta")(function* (
+const onContentBlockDelta = Effect.fnUntraced(function* (
   state: ParserState,
   event: AnthropicEvent,
 ) {

packages/core/src/session/runner/publish-llm-event.ts

@@ -385,7 +385,7 @@ export const createLLMEventPublisher = (bus: Pick<Bus.Interface, "publish">, inp
     return tool ? Effect.succeed(tool.assistantMessageID) : Effect.die(new Error(`Unknown tool call: ${id}`))
   }
 
-  const publish = Effect.fn("SessionRunner.publishLLMEvent")(function* (event: LLMEvent) {
+  const dispatch = Effect.fnUntraced(function* (event: LLMEvent) {
     switch (event.type) {
       case "step-start":
         yield* startAssistant()
@@ -542,6 +542,13 @@ export const createLLMEventPublisher = (bus: Pick<Bus.Interface, "publish">, inp
         return
     }
   })
+  const publishTraced = Effect.fn("SessionRunner.publishLLMEvent")(function* (event: LLMEvent) {
+    return yield* dispatch(event)
+  })
+  const publish = (event: LLMEvent) =>
+    event.type === "text-delta" || event.type === "reasoning-delta" || event.type === "tool-input-delta"
+      ? dispatch(event)
+      : publishTraced(event)
 
   const progress = Effect.fnUntraced(function* (id: string, update: Tool.Metadata) {
     const tool = tools.get(id)