increse llm obs size limit from 1mb to 5mb in line with python version and documentation (#7921)

Author: 1ForrestWargo1

packages/dd-trace/src/llmobs/constants/text.js

@@ -1,6 +1,6 @@
 'use strict'
 
 module.exports = {
-  DROPPED_VALUE_TEXT: "[This value has been dropped because this span's size exceeds the 1MB size limit.]",
+  DROPPED_VALUE_TEXT: "[This value has been dropped because this span's size exceeds the 5MB size limit.]",
   UNSERIALIZABLE_VALUE_TEXT: 'Unserializable value',
 }

packages/dd-trace/src/llmobs/constants/writers.js

@@ -13,5 +13,5 @@ module.exports = {
   EVALUATIONS_ENDPOINT: '/api/intake/llm-obs/v2/eval-metric',
 
   EVP_PAYLOAD_SIZE_LIMIT: 5 << 20, // 5MB (actual limit is 5.1MB)
-  EVP_EVENT_SIZE_LIMIT: (1 << 20) - 1024, // 999KB (actual limit is 1MB)
+  EVP_EVENT_SIZE_LIMIT: 5 << 20, // 5MB (actual backend limit is 10MB; Python SDK defaults to 5MB)
 }

packages/dd-trace/src/llmobs/writers/spans.js

@@ -32,7 +32,7 @@ class LLMObsSpanWriter extends BaseWriter {
     let processedEventSizeBytes = eventSizeBytes
 
     if (shouldTruncate) {
-      logger.warn(`Dropping event input/output because its size (${eventSizeBytes}) exceeds the 1MB event size limit`)
+      logger.warn(`Dropping event input/output because its size (${eventSizeBytes}) exceeds the 5MB event size limit`)
       event = this._truncateSpanEvent(event)
       processedEventSizeBytes = Buffer.byteLength(JSON.stringify(event))
     }

packages/dd-trace/test/llmobs/writers/spans.spec.js

@@ -71,8 +71,8 @@ describe('LLMObsSpanWriter', () => {
     const event = {
       name: 'test',
       meta: {
-        input: { value: 'a'.repeat(1024 * 1024) },
-        output: { value: 'a'.repeat(1024 * 1024) },
+        input: { value: 'a'.repeat(3 * 1024 * 1024) },
+        output: { value: 'a'.repeat(3 * 1024 * 1024) },
       },
     }
 
@@ -82,8 +82,8 @@ describe('LLMObsSpanWriter', () => {
     assert.deepStrictEqual(bufferEvent, {
       name: 'test',
       meta: {
-        input: { value: "[This value has been dropped because this span's size exceeds the 1MB size limit.]" },
-        output: { value: "[This value has been dropped because this span's size exceeds the 1MB size limit.]" },
+        input: { value: "[This value has been dropped because this span's size exceeds the 5MB size limit.]" },
+        output: { value: "[This value has been dropped because this span's size exceeds the 5MB size limit.]" },
       },
       collection_errors: ['dropped_io'],
     })