diff --git a/nodejs/src/ingestion/ai/otel/middleware/traceloop.test.ts b/nodejs/src/ingestion/ai/otel/middleware/traceloop.test.ts
index 7f29af5a1f58..5f81fbc9974b 100644
--- a/nodejs/src/ingestion/ai/otel/middleware/traceloop.test.ts
+++ b/nodejs/src/ingestion/ai/otel/middleware/traceloop.test.ts
@@ -204,6 +204,28 @@ describe('traceloop middleware', () => {
             expect(event.properties!['llm.usage.total_tokens']).toBeUndefined()
             expect(event.properties!['llm.response.finish_reason']).toBeUndefined()
             expect(event.properties!['llm.response.stop_reason']).toBeUndefined()
+            // stop_reason takes priority over finish_reason
+            expect(event.properties!['$ai_stop_reason']).toBe('end_turn')
+        })
+
+        it('maps finish_reason to $ai_stop_reason when stop_reason is absent', () => {
+            const event = createEvent('$ai_generation', {
+                'llm.request.type': 'chat',
+                'llm.response.finish_reason': 'stop',
+            })
+            traceloop.process(event, () => mapOtelAttributes(event))
+
+            expect(event.properties!['llm.response.finish_reason']).toBeUndefined()
+            expect(event.properties!['$ai_stop_reason']).toBe('stop')
+        })
+
+        it('leaves $ai_stop_reason undefined when neither reason is present', () => {
+            const event = createEvent('$ai_generation', {
+                'llm.request.type': 'chat',
+            })
+            traceloop.process(event, () => mapOtelAttributes(event))
+
+            expect(event.properties!['$ai_stop_reason']).toBeUndefined()
         })
     })
 })
diff --git a/nodejs/src/ingestion/ai/otel/middleware/traceloop.ts b/nodejs/src/ingestion/ai/otel/middleware/traceloop.ts
index e5260df709ae..d072c5c3f1bf 100644
--- a/nodejs/src/ingestion/ai/otel/middleware/traceloop.ts
+++ b/nodejs/src/ingestion/ai/otel/middleware/traceloop.ts
@@ -11,8 +11,6 @@ const STRIP_KEYS = [
     'traceloop.entity.output',
     'llm.is_streaming',
     'llm.usage.total_tokens',
-    'llm.response.finish_reason',
-    'llm.response.stop_reason',
 ]
 
 interface IndexedEntry {
@@ -157,6 +155,16 @@ function process(event: PluginEvent, next: () => void): void {
         }
     }
 
+    // Map stop/finish reason to $ai_stop_reason before stripping
+    if (props['$ai_stop_reason'] === undefined) {
+        const stopReason = props['llm.response.stop_reason'] ?? props['llm.response.finish_reason']
+        if (stopReason !== undefined) {
+            props['$ai_stop_reason'] = stopReason
+        }
+    }
+    delete props['llm.response.stop_reason']
+    delete props['llm.response.finish_reason']
+
     props['$ai_lib'] = 'opentelemetry/traceloop'
 
     for (const key of STRIP_KEYS) {
diff --git a/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.test.ts b/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.test.ts
index fa53479e4ba1..e18b8fa0f6d1 100644
--- a/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.test.ts
+++ b/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.test.ts
@@ -94,6 +94,27 @@ describe('vercel-ai middleware', () => {
                 expect(key).not.toBe('operation.name')
                 expect(key).not.toBe('resource.name')
             }
+            expect(event.properties!['$ai_stop_reason']).toBe('stop')
+        })
+
+        it('maps gen_ai.response.finish_reasons array to $ai_stop_reason', () => {
+            const event = createEvent('$ai_generation', {
+                'ai.operationId': 'ai.generateText.doGenerate',
+                'gen_ai.response.finish_reasons': ['length'],
+            })
+            convertOtelEvent(event)
+
+            expect(event.properties!['gen_ai.response.finish_reasons']).toBeUndefined()
+            expect(event.properties!['$ai_stop_reason']).toBe('length')
+        })
+
+        it('leaves $ai_stop_reason undefined when no finish reason is present', () => {
+            const event = createEvent('$ai_generation', {
+                'ai.operationId': 'ai.generateText.doGenerate',
+            })
+            convertOtelEvent(event)
+
+            expect(event.properties!['$ai_stop_reason']).toBeUndefined()
         })
     })
 
diff --git a/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.ts b/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.ts
index cb37071402e8..54aca212c6de 100644
--- a/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.ts
+++ b/nodejs/src/ingestion/ai/otel/middleware/vercel-ai.ts
@@ -18,7 +18,6 @@ const STRIP_KEYS = [
     'ai.usage.promptTokens',
     'ai.usage.completionTokens',
     'ai.usage.tokens',
-    'ai.response.finishReason',
     'ai.response.id',
     'ai.response.model',
     'ai.response.timestamp',
@@ -43,7 +42,6 @@ const STRIP_KEYS = [
     'resource.name',
     // Standard GenAI semantic convention attributes not mapped to $ai_* properties
     'gen_ai.request.max_tokens',
-    'gen_ai.response.finish_reasons',
     'gen_ai.response.id',
 ]
 
@@ -157,6 +155,19 @@ function process(event: PluginEvent, next: () => void): void {
         }
     }
 
+    // Map finish reason to $ai_stop_reason before stripping
+    if (props['$ai_stop_reason'] === undefined) {
+        const vercelReason = props['ai.response.finishReason']
+        const genAiReasons = props['gen_ai.response.finish_reasons']
+        if (vercelReason !== undefined) {
+            props['$ai_stop_reason'] = vercelReason
+        } else if (Array.isArray(genAiReasons) && genAiReasons.length > 0) {
+            props['$ai_stop_reason'] = genAiReasons[0]
+        }
+    }
+    delete props['ai.response.finishReason']
+    delete props['gen_ai.response.finish_reasons']
+
     props['$ai_lib'] = 'opentelemetry/vercel-ai'
 
     for (const key of STRIP_KEYS) {