From 3827f4d0973d6596aaf9167dafefd7dfa2c0be4c Mon Sep 17 00:00:00 2001
From: okxint <cashmein.eth@gmail.com>
Date: Fri, 9 Oct 2026 15:21:24 +0530
Subject: [PATCH] fix: use BigInt arithmetic for nanosecond timestamp
 conversion

Multiplying Date.getTime() by 1_000_000 as a float before converting
to BigInt causes IEEE 754 precision loss once the product exceeds
Number.MAX_SAFE_INTEGER (~9007T, which ms * 1e6 hits around 2255 AD).

The correct pattern already exists in convertDateToNanoseconds():
  BigInt(date.getTime()) * BigInt(1_000_000)

Apply it consistently to the three call sites that still use the
float-multiply pattern (getNowInNanoseconds, calculateDurationFromStart,
and the runEngineHandlers retry-event recordEvent call).
---
 .server-changes/fix-otlp-nanosecond-bigint-precision.md | 6 ++++++
 apps/webapp/app/v3/eventRepository/common.server.ts     | 4 ++--
 apps/webapp/app/v3/eventRepository/index.server.ts      | 2 +-
 apps/webapp/app/v3/runEngineHandlers.server.ts          | 2 +-
 4 files changed, 10 insertions(+), 4 deletions(-)
 create mode 100644 .server-changes/fix-otlp-nanosecond-bigint-precision.md

diff --git a/.server-changes/fix-otlp-nanosecond-bigint-precision.md b/.server-changes/fix-otlp-nanosecond-bigint-precision.md
new file mode 100644
index 00000000000..c3fc806cfa6
--- /dev/null
+++ b/.server-changes/fix-otlp-nanosecond-bigint-precision.md
@@ -0,0 +1,6 @@
+---
+area: webapp
+type: fix
+---
+
+Fix OTLP trace timestamps losing precision for runs after approximately 2255 AD. Timestamps are now computed with full 64-bit integer arithmetic.
diff --git a/apps/webapp/app/v3/eventRepository/common.server.ts b/apps/webapp/app/v3/eventRepository/common.server.ts
index 346e2ab6419..3dce9202eca 100644
--- a/apps/webapp/app/v3/eventRepository/common.server.ts
+++ b/apps/webapp/app/v3/eventRepository/common.server.ts
@@ -26,7 +26,7 @@ export function extractContextFromCarrier(carrier: Record<string, unknown>) {
 }
 
 export function getNowInNanoseconds(): bigint {
-  return BigInt(new Date().getTime() * 1_000_000);
+  return BigInt(new Date().getTime()) * BigInt(1_000_000);
 }
 
 export function getDateFromNanoseconds(nanoseconds: bigint): Date {
@@ -40,7 +40,7 @@ export function calculateDurationFromStart(
 ) {
   const $endtime = typeof endTime === "string" ? new Date(endTime) : endTime;
 
-  const duration = Number(BigInt($endtime.getTime() * 1_000_000) - startTime);
+  const duration = Number(BigInt($endtime.getTime()) * BigInt(1_000_000) - startTime);
 
   if (minimumDuration && duration < minimumDuration) {
     return minimumDuration;
diff --git a/apps/webapp/app/v3/eventRepository/index.server.ts b/apps/webapp/app/v3/eventRepository/index.server.ts
index c599f4e6b96..670ec60f014 100644
--- a/apps/webapp/app/v3/eventRepository/index.server.ts
+++ b/apps/webapp/app/v3/eventRepository/index.server.ts
@@ -208,7 +208,7 @@ async function recordRunEvent(
         runId: foundRun.friendlyId,
         ...attributes,
       },
-      startTime: BigInt((startTime?.getTime() ?? Date.now()) * 1_000_000),
+      startTime: BigInt(startTime?.getTime() ?? Date.now()) * BigInt(1_000_000),
       ...optionsRest,
     });
 
diff --git a/apps/webapp/app/v3/runEngineHandlers.server.ts b/apps/webapp/app/v3/runEngineHandlers.server.ts
index ee4ef2e278d..08e3194bfc7 100644
--- a/apps/webapp/app/v3/runEngineHandlers.server.ts
+++ b/apps/webapp/app/v3/runEngineHandlers.server.ts
@@ -557,7 +557,7 @@ export function registerRunEngineEventBusHandlers() {
         );
 
         await eventRepository.recordEvent(retryMessage, {
-          startTime: BigInt(time.getTime() * 1000000),
+          startTime: BigInt(time.getTime()) * BigInt(1_000_000),
           taskSlug: run.taskIdentifier,
           environment,
           attributes: {