Function onChunk

packages/ai-event-client/src/devtools-middleware.ts:332–456

(ctx, rawChunk)

    },

    onChunk(ctx, rawChunk) {
      if (!isKnownChunk(rawChunk)) return
      const chunk = rawChunk
      const base = buildEventContext(ctx)

      switch (chunk.type) {
        case 'TEXT_MESSAGE_CONTENT': {
          if (chunk.content) {
            localAccumulatedContent = chunk.content
          } else {
            localAccumulatedContent += chunk.delta
          }
          safeEmit('text:chunk:content', {
            ...base,
            messageId: localMessageId || undefined,
            content: localAccumulatedContent,
            delta: chunk.delta,
            timestamp: Date.now(),
          })
          break
        }
        case 'TOOL_CALL_START': {
          const toolIndex = chunk.index ?? 0
          const toolName = chunk.toolCallName
          activeToolCalls.set(chunk.toolCallId, {
            toolName,
            index: toolIndex,
          })
          safeEmit('text:chunk:tool-call', {
            ...base,
            messageId: localMessageId || undefined,
            toolCallId: chunk.toolCallId,
            toolName,
            index: toolIndex,
            arguments: '',
            timestamp: Date.now(),
          })
          break
        }
        case 'TOOL_CALL_ARGS': {
          const active = activeToolCalls.get(chunk.toolCallId)
          safeEmit('text:chunk:tool-call', {
            ...base,
            messageId: localMessageId || undefined,
            toolCallId: chunk.toolCallId,
            toolName: active?.toolName ?? '',
            index: active?.index ?? 0,
            arguments: chunk.delta,
            timestamp: Date.now(),
          })
          break
        }
        case 'TOOL_CALL_END': {
          activeToolCalls.delete(chunk.toolCallId)
          safeEmit('text:chunk:tool-result', {
            ...base,
            messageId: localMessageId || undefined,
            toolCallId: chunk.toolCallId,