@posthog/ai/src/openai/index.ts

PostHog Node.js AI integrations

import OpenAIOrignal, { ClientOptions } from 'openai'
import { PostHog } from 'posthog-node'
import { v4 as uuidv4 } from 'uuid'
import { formatResponseOpenAI, MonitoringParams, sendEventToPosthog } from '../utils'
import type { APIPromise } from 'openai'
import type { Stream } from 'openai/streaming'
import type { ParsedResponse } from 'openai/resources/responses/responses'

type ChatCompletion = OpenAIOrignal.ChatCompletion
type ChatCompletionChunk = OpenAIOrignal.ChatCompletionChunk
type ChatCompletionCreateParamsBase = OpenAIOrignal.Chat.Completions.ChatCompletionCreateParams
type ChatCompletionCreateParamsNonStreaming = OpenAIOrignal.Chat.Completions.ChatCompletionCreateParamsNonStreaming
type ChatCompletionCreateParamsStreaming = OpenAIOrignal.Chat.Completions.ChatCompletionCreateParamsStreaming
type ResponsesCreateParamsBase = OpenAIOrignal.Responses.ResponseCreateParams
type ResponsesCreateParamsNonStreaming = OpenAIOrignal.Responses.ResponseCreateParamsNonStreaming
type ResponsesCreateParamsStreaming = OpenAIOrignal.Responses.ResponseCreateParamsStreaming

interface MonitoringOpenAIConfig extends ClientOptions {
  apiKey: string
  posthog: PostHog
  baseURL?: string
}

type RequestOptions = Record<string, any>

export class PostHogOpenAI extends OpenAIOrignal {
  private readonly phClient: PostHog
  public chat: WrappedChat
  public responses: WrappedResponses

  constructor(config: MonitoringOpenAIConfig) {
    const { posthog, ...openAIConfig } = config
    super(openAIConfig)
    this.phClient = posthog
    this.chat = new WrappedChat(this, this.phClient)
    this.responses = new WrappedResponses(this, this.phClient)
  }
}

export class WrappedChat extends OpenAIOrignal.Chat {
  constructor(parentClient: PostHogOpenAI, phClient: PostHog) {
    super(parentClient)
    this.completions = new WrappedCompletions(parentClient, phClient)
  }

  public completions: WrappedCompletions
}

export class WrappedCompletions extends OpenAIOrignal.Chat.Completions {
  private readonly phClient: PostHog

  constructor(client: OpenAIOrignal, phClient: PostHog) {
    super(client)
    this.phClient = phClient
  }

  // --- Overload #1: Non-streaming
  public create(
    body: ChatCompletionCreateParamsNonStreaming & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<ChatCompletion>

  // --- Overload #2: Streaming
  public create(
    body: ChatCompletionCreateParamsStreaming & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<Stream<ChatCompletionChunk>>

  // --- Overload #3: Generic base
  public create(
    body: ChatCompletionCreateParamsBase & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<ChatCompletion | Stream<ChatCompletionChunk>>

  // --- Implementation Signature
  public create(
    body: ChatCompletionCreateParamsBase & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<ChatCompletion | Stream<ChatCompletionChunk>> {
    const {
      posthogDistinctId,
      posthogTraceId,
      posthogProperties,
      // eslint-disable-next-line @typescript-eslint/no-unused-vars
      posthogPrivacyMode = false,
      posthogGroups,
      posthogCaptureImmediate,
      ...openAIParams
    } = body

    const traceId = posthogTraceId ?? uuidv4()
    const startTime = Date.now()

    const parentPromise = super.create(openAIParams, options)

    if (openAIParams.stream) {
      return parentPromise.then((value) => {
        if ('tee' in value) {
          const [stream1, stream2] = value.tee()
          ;(async () => {
            try {
              let accumulatedContent = ''
              let usage: {
                inputTokens?: number
                outputTokens?: number
                reasoningTokens?: number
                cacheReadInputTokens?: number
              } = {
                inputTokens: 0,
                outputTokens: 0,
              }

              for await (const chunk of stream1) {
                const delta = chunk?.choices?.[0]?.delta?.content ?? ''
                accumulatedContent += delta
                if (chunk.usage) {
                  usage = {
                    inputTokens: chunk.usage.prompt_tokens ?? 0,
                    outputTokens: chunk.usage.completion_tokens ?? 0,
                    reasoningTokens: chunk.usage.completion_tokens_details?.reasoning_tokens ?? 0,
                    cacheReadInputTokens: chunk.usage.prompt_tokens_details?.cached_tokens ?? 0,
                  }
                }
              }

              const latency = (Date.now() - startTime) / 1000
              await sendEventToPosthog({
                client: this.phClient,
                distinctId: posthogDistinctId ?? traceId,
                traceId,
                model: openAIParams.model,
                provider: 'openai',
                input: openAIParams.messages,
                output: [{ content: accumulatedContent, role: 'assistant' }],
                latency,
                baseURL: (this as any).baseURL ?? '',
                params: body,
                httpStatus: 200,
                usage,
                captureImmediate: posthogCaptureImmediate,
              })
            } catch (error: any) {
              await sendEventToPosthog({
                client: this.phClient,
                distinctId: posthogDistinctId ?? traceId,
                traceId,
                model: openAIParams.model,
                provider: 'openai',
                input: openAIParams.messages,
                output: [],
                latency: 0,
                baseURL: (this as any).baseURL ?? '',
                params: body,
                httpStatus: error?.status ? error.status : 500,
                usage: { inputTokens: 0, outputTokens: 0 },
                isError: true,
                error: JSON.stringify(error),
                captureImmediate: posthogCaptureImmediate,
              })
            }
          })()

          // Return the other stream to the user
          return stream2
        }
        return value
      }) as APIPromise<Stream<ChatCompletionChunk>>
    } else {
      const wrappedPromise = parentPromise.then(
        async (result) => {
          if ('choices' in result) {
            const latency = (Date.now() - startTime) / 1000
            await sendEventToPosthog({
              client: this.phClient,
              distinctId: posthogDistinctId ?? traceId,
              traceId,
              model: openAIParams.model,
              provider: 'openai',
              input: openAIParams.messages,
              output: formatResponseOpenAI(result),
              latency,
              baseURL: (this as any).baseURL ?? '',
              params: body,
              httpStatus: 200,
              usage: {
                inputTokens: result.usage?.prompt_tokens ?? 0,
                outputTokens: result.usage?.completion_tokens ?? 0,
                reasoningTokens: result.usage?.completion_tokens_details?.reasoning_tokens ?? 0,
                cacheReadInputTokens: result.usage?.prompt_tokens_details?.cached_tokens ?? 0,
              },
              captureImmediate: posthogCaptureImmediate,
            })
          }
          return result
        },
        async (error: any) => {
          await sendEventToPosthog({
            client: this.phClient,
            distinctId: posthogDistinctId ?? traceId,
            traceId,
            model: openAIParams.model,
            provider: 'openai',
            input: openAIParams.messages,
            output: [],
            latency: 0,
            baseURL: (this as any).baseURL ?? '',
            params: body,
            httpStatus: error?.status ? error.status : 500,
            usage: {
              inputTokens: 0,
              outputTokens: 0,
            },
            isError: true,
            error: JSON.stringify(error),
            captureImmediate: posthogCaptureImmediate,
          })
          throw error
        }
      ) as APIPromise<ChatCompletion>

      return wrappedPromise
    }
  }
}

export class WrappedResponses extends OpenAIOrignal.Responses {
  private readonly phClient: PostHog

  constructor(client: OpenAIOrignal, phClient: PostHog) {
    super(client)
    this.phClient = phClient
  }

  // --- Overload #1: Non-streaming
  public create(
    body: ResponsesCreateParamsNonStreaming & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<OpenAIOrignal.Responses.Response>

  // --- Overload #2: Streaming
  public create(
    body: ResponsesCreateParamsStreaming & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<Stream<OpenAIOrignal.Responses.ResponseStreamEvent>>

  // --- Overload #3: Generic base
  public create(
    body: ResponsesCreateParamsBase & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<OpenAIOrignal.Responses.Response | Stream<OpenAIOrignal.Responses.ResponseStreamEvent>>

  // --- Implementation Signature
  public create(
    body: ResponsesCreateParamsBase & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<OpenAIOrignal.Responses.Response | Stream<OpenAIOrignal.Responses.ResponseStreamEvent>> {
    const {
      posthogDistinctId,
      posthogTraceId,
      posthogProperties,
      // eslint-disable-next-line @typescript-eslint/no-unused-vars
      posthogPrivacyMode = false,
      posthogGroups,
      posthogCaptureImmediate,
      ...openAIParams
    } = body

    const traceId = posthogTraceId ?? uuidv4()
    const startTime = Date.now()

    const parentPromise = super.create(openAIParams, options)

    if (openAIParams.stream) {
      return parentPromise.then((value) => {
        if ('tee' in value && typeof (value as any).tee === 'function') {
          const [stream1, stream2] = (value as any).tee()
          ;(async () => {
            try {
              let finalContent: any[] = []
              let usage: {
                inputTokens?: number
                outputTokens?: number
                reasoningTokens?: number
                cacheReadInputTokens?: number
              } = {
                inputTokens: 0,
                outputTokens: 0,
              }

              for await (const chunk of stream1) {
                if (
                  chunk.type === 'response.completed' &&
                  'response' in chunk &&
                  chunk.response?.output &&
                  chunk.response.output.length > 0
                ) {
                  finalContent = chunk.response.output
                }
                if ('response' in chunk && chunk.response?.usage) {
                  usage = {
                    inputTokens: chunk.response.usage.input_tokens ?? 0,
                    outputTokens: chunk.response.usage.output_tokens ?? 0,
                    reasoningTokens: chunk.response.usage.output_tokens_details?.reasoning_tokens ?? 0,
                    cacheReadInputTokens: chunk.response.usage.input_tokens_details?.cached_tokens ?? 0,
                  }
                }
              }

              const latency = (Date.now() - startTime) / 1000
              await sendEventToPosthog({
                client: this.phClient,
                distinctId: posthogDistinctId ?? traceId,
                traceId,
                model: openAIParams.model,
                provider: 'openai',
                input: openAIParams.input,
                output: finalContent,
                latency,
                baseURL: (this as any).baseURL ?? '',
                params: body,
                httpStatus: 200,
                usage,
                captureImmediate: posthogCaptureImmediate,
              })
            } catch (error: any) {
              await sendEventToPosthog({
                client: this.phClient,
                distinctId: posthogDistinctId ?? traceId,
                traceId,
                model: openAIParams.model,
                provider: 'openai',
                input: openAIParams.input,
                output: [],
                latency: 0,
                baseURL: (this as any).baseURL ?? '',
                params: body,
                httpStatus: error?.status ? error.status : 500,
                usage: { inputTokens: 0, outputTokens: 0 },
                isError: true,
                error: JSON.stringify(error),
                captureImmediate: posthogCaptureImmediate,
              })
            }
          })()

          return stream2
        }
        return value
      }) as APIPromise<Stream<OpenAIOrignal.Responses.ResponseStreamEvent>>
    } else {
      const wrappedPromise = parentPromise.then(
        async (result) => {
          if ('output' in result) {
            const latency = (Date.now() - startTime) / 1000
            await sendEventToPosthog({
              client: this.phClient,
              distinctId: posthogDistinctId ?? traceId,
              traceId,
              model: openAIParams.model,
              provider: 'openai',
              input: openAIParams.input,
              output: result.output,
              latency,
              baseURL: (this as any).baseURL ?? '',
              params: body,
              httpStatus: 200,
              usage: {
                inputTokens: result.usage?.input_tokens ?? 0,
                outputTokens: result.usage?.output_tokens ?? 0,
                reasoningTokens: result.usage?.output_tokens_details?.reasoning_tokens ?? 0,
                cacheReadInputTokens: result.usage?.input_tokens_details?.cached_tokens ?? 0,
              },
              captureImmediate: posthogCaptureImmediate,
            })
          }
          return result
        },
        async (error: any) => {
          await sendEventToPosthog({
            client: this.phClient,
            distinctId: posthogDistinctId ?? traceId,
            traceId,
            model: openAIParams.model,
            provider: 'openai',
            input: openAIParams.input,
            output: [],
            latency: 0,
            baseURL: (this as any).baseURL ?? '',
            params: body,
            httpStatus: error?.status ? error.status : 500,
            usage: {
              inputTokens: 0,
              outputTokens: 0,
            },
            isError: true,
            error: JSON.stringify(error),
            captureImmediate: posthogCaptureImmediate,
          })
          throw error
        }
      ) as APIPromise<OpenAIOrignal.Responses.Response>

      return wrappedPromise
    }
  }

  public parse<Params extends ResponsesCreateParamsBase, ParsedT = any>(
    body: Params & MonitoringParams,
    options?: RequestOptions
  ): APIPromise<ParsedResponse<ParsedT>> {
    const {
      posthogDistinctId,
      posthogTraceId,
      posthogProperties,
      // eslint-disable-next-line @typescript-eslint/no-unused-vars
      posthogPrivacyMode = false,
      posthogGroups,
      posthogCaptureImmediate,
      ...openAIParams
    } = body

    const traceId = posthogTraceId ?? uuidv4()
    const startTime = Date.now()

    // Create a temporary instance that bypasses our wrapped create method
    const originalCreate = super.create.bind(this)
    const originalSelf = this as any
    const tempCreate = originalSelf.create
    originalSelf.create = originalCreate

    try {
      const parentPromise = super.parse(openAIParams, options)

      const wrappedPromise = parentPromise.then(
        async (result) => {
          const latency = (Date.now() - startTime) / 1000
          await sendEventToPosthog({
            client: this.phClient,
            distinctId: posthogDistinctId ?? traceId,
            traceId,
            model: openAIParams.model,
            provider: 'openai',
            input: openAIParams.input,
            output: result.output,
            latency,
            baseURL: (this as any).baseURL ?? '',
            params: body,
            httpStatus: 200,
            usage: {
              inputTokens: result.usage?.input_tokens ?? 0,
              outputTokens: result.usage?.output_tokens ?? 0,
              reasoningTokens: result.usage?.output_tokens_details?.reasoning_tokens ?? 0,
              cacheReadInputTokens: result.usage?.input_tokens_details?.cached_tokens ?? 0,
            },
            captureImmediate: posthogCaptureImmediate,
          })
          return result
        },
        async (error: any) => {
          await sendEventToPosthog({
            client: this.phClient,
            distinctId: posthogDistinctId ?? traceId,
            traceId,
            model: openAIParams.model,
            provider: 'openai',
            input: openAIParams.input,
            output: [],
            latency: 0,
            baseURL: (this as any).baseURL ?? '',
            params: body,
            httpStatus: error?.status ? error.status : 500,
            usage: {
              inputTokens: 0,
              outputTokens: 0,
            },
            isError: true,
            error: JSON.stringify(error),
            captureImmediate: posthogCaptureImmediate,
          })
          throw error
        }
      )

      return wrappedPromise as APIPromise<ParsedResponse<ParsedT>>
    } finally {
      // Restore our wrapped create method
      originalSelf.create = tempCreate
    }
  }
}

export default PostHogOpenAI

export { PostHogOpenAI as OpenAI }