LangChain/LangGraph llm event refactor

Author: amychisholm03

lib/llm-events-new/base.js

@@ -31,8 +31,8 @@ class LlmEvent {
    * @param {object} params.segment Current segment
    * @param {object} params.transaction Current and active transaction
    * @param {string} params.vendor Lowercase vendor name, e.g. "openai"
-   * @param {string} params.responseModel Model name from response
-   * @param {string} params.requestId ID from request/response headers
+   * @param {string} [params.responseModel] Model name from response
+   * @param {string} [params.requestId] ID from request/response headers
    * @param {boolean} [params.error] Set to `true` if an error occurred during creation call, omitted if no error occurred
    */
   constructor({ agent, segment, transaction, vendor, responseModel, requestId, error }) {
@@ -41,6 +41,9 @@ class LlmEvent {
     this.trace_id = transaction?.traceId
     this.vendor = vendor
     this.metadata = agent
+    // TODO: Does not appear in AIM spec, but was a
+    // requirement for LangChain instrumentation back in 2024?
+    // this.appName = agent.config.applications()[0]
 
     // Omit `error` property if no error occurred
     if (error === true) {

lib/llm-events-new/chat-summary.js

@@ -41,12 +41,13 @@ class LlmChatCompletionSummary extends LlmEvent {
     responseOrg, temperature, maxTokens, numMsgs, finishReason }) {
     super({ agent, segment, transaction, vendor, responseModel, requestId, error })
 
-    this['request.model'] = requestModel
-    this['request.max_tokens'] = maxTokens
-    this['request.temperature'] = temperature
-    this['response.number_of_messages'] = numMsgs
+    if (requestModel) this['request.model'] = requestModel
+    if (maxTokens) this['request.max_tokens'] = maxTokens
+    if (temperature) this['request.temperature'] = temperature
     if (finishReason) this['response.choices.finish_reason'] = finishReason
     if (responseOrg) this['response.organization'] = responseOrg
+
+    this['response.number_of_messages'] = numMsgs
     this.timestamp = segment.timer.start
     this.duration = segment.getDurationInMillis()
   }

lib/llm-events-new/langchain/chat-message.js

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+'use strict'
+const LlmChatCompletionMessage = require('../chat-message')
+const { isSimpleObject } = require('../../util/objects')
+
+/**
+ * Encapsulates a LangChain LlmChatCompletionMessage.
+ */
+class LangChainLlmChatCompletionMessage extends LlmChatCompletionMessage {
+  virtual_llm = true
+  /**
+   * @param {object} params constructor parameters
+   * @param {Agent} params.agent New Relic agent instance
+   * @param {object} params.segment Current segment
+   * @param {object} params.transaction Current and active transaction
+   * @param {string} params.runId LangChain run ID (will be used as response ID)
+   * @param {number} params.sequence Index (beginning at 0) associated with
+   *    each message including the prompt and responses
+   * @param {string} params.content Content of the message
+   * @param {string} [params.role] Role of the message creator (e.g. `user`, `assistant`, `tool`)
+   * @param {string} params.completionId ID of the `LlmChatCompletionSummary` event that
+   *    this message event is connected to
+   * @param {boolean} [params.isResponse] `true` if a message is the result of a chat
+   *    completion and not an input message - omitted in `false` cases
+   * @param {object} params.metadata LangChain metadata object
+   * @param {object[]} params.tags LangChain tags
+   */
+  constructor({ agent, segment, transaction, runId, sequence, role, content, completionId, isResponse, metadata, tags }) {
+    super({ agent,
+      segment,
+      transaction,
+      vendor: 'langchain',
+      responseId: runId,
+      requestId: runId,
+      sequence,
+      content,
+      role,
+      completionId,
+      isResponse })
+
+    // TODO: Does not appear in AIM spec, but was a
+    // requirement for LangChain instrumentation back in 2024?
+    this.appName = agent.config.applications()[0]
+    this.langchainMeta = metadata
+    this.tags = Array.isArray(tags) ? tags.join(',') : tags
+  }
+
+  // eslint-disable-next-line accessor-pairs
+  set langchainMeta(value) {
+    if (isSimpleObject(value) === false) {
+      return
+    }
+    for (const [key, val] of Object.entries(value)) {
+      this[`metadata.${key}`] = val
+    }
+  }
+}
+
+module.exports = LangChainLlmChatCompletionMessage

lib/llm-events-new/langchain/chat-summary.js

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+'use strict'
+const LlmChatCompletionSummary = require('../chat-summary')
+const { isSimpleObject } = require('../../util/objects')
+
+/**
+ * Encapsulates a LangChain LlmChatCompletionSummary.
+ */
+class LangChainLlmChatCompletionSummary extends LlmChatCompletionSummary {
+  virtual_llm = true
+  constructor({ agent, segment, transaction, error, numMsgs = 0, runId, metadata = {}, tags = '' }) {
+    super({ agent,
+      segment,
+      transaction,
+      vendor: 'langchain',
+      requestId: runId,
+      error,
+      numMsgs })
+
+    // TODO: Does not appear in AIM spec, but was a
+    // requirement for LangChain instrumentation back in 2024?
+    this.appName = agent.config.applications()[0]
+    this.langchainMeta = metadata
+    this.tags = Array.isArray(tags) ? tags.join(',') : tags
+  }
+
+  // eslint-disable-next-line accessor-pairs
+  set langchainMeta(value) {
+    if (isSimpleObject(value) === false) {
+      return
+    }
+    for (const [key, val] of Object.entries(value)) {
+      this[`metadata.${key}`] = val
+    }
+  }
+}
+
+module.exports = LangChainLlmChatCompletionSummary

lib/llm-events-new/langchain/index.js

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+'use strict'
+
+const LlmChatCompletionMessage = require('./chat-message')
+const LlmChatCompletionSummary = require('./chat-summary')
+const LlmTool = require('./tool')
+const LlmVectorSearch = require('./vector-search')
+const LlmVectorSearchResult = require('./vector-search-result')
+
+module.exports = {
+  LlmChatCompletionMessage,
+  LlmChatCompletionSummary,
+  LlmTool,
+  LlmVectorSearch,
+  LlmVectorSearchResult
+}

lib/llm-events-new/langchain/tool.js

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const LlmTool = require('../tool')
+const { isSimpleObject } = require('../../util/objects')
+
+/**
+ * Encapsulates a LangChain LlmTool event.
+ */
+class LangChainLlmTool extends LlmTool {
+  constructor({ agent, segment, transaction, runId, input, output, toolName, aiAgentName, description, metadata = {}, tags = '', error }) {
+    super({ agent, segment, transaction, vendor: 'langchain', runId, input, output, toolName, aiAgentName, error })
+
+    // TODO: Does not appear in AIM spec, but was a
+    // requirement for LangChain instrumentation back in 2024?
+    this.appName = agent.config.applications()[0]
+    this.langchainMeta = metadata
+    this.tags = Array.isArray(tags) ? tags.join(',') : tags
+    this.description = description
+  }
+
+  // eslint-disable-next-line accessor-pairs
+  set langchainMeta(value) {
+    if (isSimpleObject(value) === false) {
+      return
+    }
+    for (const [key, val] of Object.entries(value)) {
+      this[`metadata.${key}`] = val
+    }
+  }
+}
+
+module.exports = LangChainLlmTool

lib/llm-events-new/langchain/vector-search-result.js

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const LlmEvent = require('../base')
+const { isSimpleObject } = require('../../util/objects')
+
+/**
+ * An event that captures data about a VectorStore `similaritySearch` call in LangChain.
+ *
+ * An instance of `LlmVectorSearchResult` represents a single document returned by
+ * the similarity search.
+ */
+class LangChainLlmVectorSearchResult extends LlmEvent {
+  /**
+   * @param {object} params constructor parameters
+   * @param {Agent} params.agent New Relic agent instance
+   * @param {object} params.segment Current segment
+   * @param {object} params.transaction Current and active transaction
+   * @param {string} params.searchId UUID to identify the search
+   * @param {number} params.sequence Index of the document in the search result documents list
+   * @param {string} params.pageContent Stringified contents of the `pageContent` attribute on each returned search result document
+   * @param {object} params.metadata The metadata object on each returned search result document
+   */
+  constructor({ agent, segment, transaction, searchId, sequence = 0, pageContent = '', metadata = {} }) {
+    super({ agent, segment, transaction, vendor: 'langchain' })
+
+    this.search_id = searchId
+    this.sequence = sequence
+
+    if (agent.config.ai_monitoring.record_content.enabled === true) {
+      this.page_content = pageContent
+    }
+
+    // TODO: Does not appear in AIM spec, but was a
+    // requirement for LangChain instrumentation back in 2024?
+    this.appName = agent.config.applications()[0]
+    this.langchainMeta = metadata
+  }
+
+  // eslint-disable-next-line accessor-pairs
+  set langchainMeta(value) {
+    if (isSimpleObject(value) === false) {
+      return
+    }
+    for (const [key, val] of Object.entries(value)) {
+      this[`metadata.${key}`] = val
+    }
+  }
+}
+
+module.exports = LangChainLlmVectorSearchResult

lib/llm-events-new/langchain/vector-search.js

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const LlmEvent = require('../base')
+
+/**
+ * An event that captures data about a VectorStore `similaritySearch` call in LangChain.
+ *
+ * An instance of `LlmVectorSearch` represents the entire search request.
+ */
+class LangChainLlmVectorSearch extends LlmEvent {
+  /**
+   * @param {object} params constructor parameters
+   * @param {Agent} params.agent New Relic agent instance
+   * @param {object} params.segment Current segment
+   * @param {object} params.transaction Current and active transaction
+   * @param {string} params.query Vector search query
+   * @param {number} params.k Vector search top k
+   * @param {number} params.numDocs Number of documents in returned response
+   * @param {boolean} [params.error] Set to `true` if an error occurred during creation call, omitted if no error occurred
+   */
+  constructor({ agent, segment, transaction, k, numDocs = 0, query, error }) {
+    super({ agent, segment, transaction, vendor: 'langchain', error })
+    this.duration = segment.getDurationInMillis()
+    this['request.k'] = k
+    this['response.number_of_documents'] = numDocs
+
+    if (agent.config.ai_monitoring.record_content.enabled === true) {
+      this['request.query'] = query
+    }
+
+    // TODO: Does not appear in AIM spec, but was a
+    // requirement for LangChain instrumentation back in 2024?
+    this.appName = agent.config.applications()[0]
+  }
+}
+
+module.exports = LangChainLlmVectorSearch

lib/llm-events-new/langgraph/agent.js

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const LlmEvent = require('../base')
+
+/**
+ * Encapsulates a `@langchain/langgraph` LlmAgent event.
+ */
+class LangGraphLlmAgent extends LlmEvent {
+  /**
+   *
+   * @param {object} params constructor parameters
+   * @param {Agent} params.agent New Relic agent instance
+   * @param {object} params.segment Current segment
+   * @param {object} params.transaction Current and active transaction
+   * @param {string} params.aiAgentName Name of the AI agent which can typically be captured through framework context
+   * @param {boolean} [params.error] Set to `true` if an error occurred during creation call, omitted if no error occurred
+   */
+  constructor({ agent, segment, transaction, aiAgentName, error }) {
+    super({ agent, segment, transaction, vendor: 'langgraph', error })
+    this.name = aiAgentName ?? 'agent'
+  }
+}
+
+module.exports = LangGraphLlmAgent

lib/llm-events-new/tool.js

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2026 New Relic Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const LlmEvent = require('./base')
+
+/**
+ * An event that captures data about a tool call made by an AI agent.
+ */
+class LlmTool extends LlmEvent {
+  /**
+   *
+   * @param {object} params constructor parameters
+   * @param {Agent} params.agent New Relic agent instance
+   * @param {object} params.segment Current segment
+   * @param {object} params.transaction Current and active transaction
+   * @param {string} params.vendor Lowercase vendor name, e.g. "openai"
+   * @param {string} params.input Argument(s) input to the tool before it is run (including the argument name and value if available)
+   * @param {string} params.output Output data returned after the tool call has completed
+   * @param {string} params.toolName Name of the tool being run
+   * @param {string} params.aiAgentName Name of the AI agent associated with the tool call
+   * @param {string} params.runId ID assigned by the framework to identify the tool call
+   * @param {boolean} [params.error] Set to `true` if an error occurred during creation call, omitted if no error occurred
+   */
+  constructor({ agent, segment, transaction, vendor, runId, input, output, toolName, aiAgentName, error }) {
+    super({ agent, segment, transaction, vendor, error })
+    // If user defined metadata is not present or available, it can be omitted from the event.
+    // All other attributes listed below MUST be captured and added to the event as the AI
+    //  Monitoring UX depends on their presence.
+    this.name = toolName
+    this.agent_name = aiAgentName
+    this.run_id = runId
+
+    if (agent.config.ai_monitoring.record_content.enabled === true) {
+      this.input = input
+      this.output = output
+    }
+  }
+}
+
+module.exports = LlmTool