Merge pull request #954 from liam-hq/devin/1742543457-langfuse-integration

Add Langfuse integration to app

Author: MH4GF

.env.template

@@ -3,6 +3,9 @@ GITHUB_APP_ID=""
 GITHUB_CLIENT_ID=""
 GITHUB_CLIENT_SECRET=""
 GITHUB_PRIVATE_KEY=""
+LANGFUSE_BASE_URL="https://cloud.langfuse.com"
+LANGFUSE_PUBLIC_KEY=""
+LANGFUSE_SECRET_KEY=""
 MIGRATION_ENABLED=""
 NEXT_PUBLIC_BASE_URL=""
 NEXT_PUBLIC_ENV_NAME=""

docs/packages-license.md

@@ -2,7 +2,7 @@
 
 
 ## Summary
-* 1144 MIT
+* 1151 MIT
 * 120 Apache 2.0
 * 80 ISC
 * 31 New BSD
@@ -1264,6 +1264,17 @@ LGPL-3.0-or-later permitted
 
 
 
+<a name="@langchain/textsplitters"></a>
+### @langchain/textsplitters v0.1.0
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
 <a name="@manypkg/find-root"></a>
 ### @manypkg/find-root v1.1.0
 #### 
@@ -9977,6 +9988,17 @@ Public Domain manually approved
 
 
 
+<a name="jsonpointer"></a>
+### jsonpointer v5.0.1
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
 <a name="jsonwebtoken"></a>
 ### jsonwebtoken v9.0.2
 #### 
@@ -10065,6 +10087,50 @@ Public Domain manually approved
 
 
 
+<a name="langchain"></a>
+### langchain v0.3.19
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
+<a name="langfuse"></a>
+### langfuse v3.37.0
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
+<a name="langfuse-core"></a>
+### langfuse-core v3.37.0
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
+<a name="langfuse-langchain"></a>
+### langfuse-langchain v3.36.0
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
 <a name="langsmith"></a>
 ### langsmith v0.3.13
 #### 
@@ -11726,6 +11792,17 @@ Public Domain manually approved
 
 
 
+<a name="openapi-types"></a>
+### openapi-types v12.1.3
+#### 
+
+##### Paths
+* /home/runner/work/liam/liam
+
+<a href="http://opensource.org/licenses/mit-license">MIT</a> permitted
+
+
+
 <a name="optionator"></a>
 ### optionator v0.9.4
 #### 

frontend/apps/app/lib/index.ts

@@ -0,0 +1 @@
+export * from './langfuse'

frontend/apps/app/lib/langfuse.ts

@@ -0,0 +1,11 @@
+import { CallbackHandler } from 'langfuse-langchain'
+
+export const langfuseLangchainHandler = new CallbackHandler({
+  publicKey: process.env.LANGFUSE_PUBLIC_KEY,
+  secretKey: process.env.LANGFUSE_SECRET_KEY,
+  baseUrl: process.env.LANGFUSE_BASE_URL || 'https://cloud.langfuse.com',
+  // Setting flushAt to 1 sends events immediately without batching
+  flushAt: 1,
+  // Set environment name for Langfuse to track different environments
+  environment: process.env.NEXT_PUBLIC_ENV_NAME,
+})

frontend/apps/app/package.json

@@ -20,6 +20,7 @@
     "date-fns": "4.1.0",
     "dotenv": "16.4.7",
     "flags": "3.1.1",
+    "langfuse-langchain": "3.36.0",
     "minimatch": "10.0.1",
     "next": "15.2.3",
     "react": "18.3.1",

frontend/apps/app/src/functions/processGenerateReview.ts

@@ -1,6 +1,7 @@
 import { PromptTemplate } from '@langchain/core/prompts'
 import { ChatOpenAI } from '@langchain/openai'
 import { prisma } from '@liam-hq/db'
+import { langfuseLangchainHandler } from '../../lib'
 import type { GenerateReviewPayload, ReviewResponse } from '../types'
 
 const REVIEW_TEMPLATE = `
@@ -35,7 +36,10 @@ export async function processGenerateReview(
     })
 
     const docsContent = docs
-      .map((doc) => `# ${doc.title}\n\n${doc.content}`)
+      .map(
+        (doc: { title: string; content: string }) =>
+          `# ${doc.title}\n\n${doc.content}`,
+      )
       .join('\n\n---\n\n')
     const prompt = PromptTemplate.fromTemplate(REVIEW_TEMPLATE)
 
@@ -45,11 +49,16 @@ export async function processGenerateReview(
     })
 
     const chain = prompt.pipe(model)
-    const response = await chain.invoke({
-      docsContent,
-      schemaFiles: payload.schemaFiles,
-      schemaChanges: payload.schemaChanges,
-    })
+    const response = await chain.invoke(
+      {
+        docsContent,
+        schemaFiles: payload.schemaFiles,
+        schemaChanges: payload.schemaChanges,
+      },
+      {
+        callbacks: [langfuseLangchainHandler],
+      },
+    )
 
     return response.content.toString()
   } catch (error) {