From a1253482b4240665bc2afb84fc1fda33537d097d Mon Sep 17 00:00:00 2001
From: kmaclip <claygeo6@gmail.com>
Date: Fri, 3 Apr 2026 15:54:00 -0400
Subject: [PATCH] fix: convert to BigInt before nanosecond multiplication to
 avoid precision loss

Multiplying epoch milliseconds by 1,000,000 as a Number exceeds
Number.MAX_SAFE_INTEGER (~9e15), causing IEEE 754 precision loss
of ~256ns in ~0.2% of cases. Convert to BigInt first, then multiply.

Fixed in 4 locations:
- getNowInNanoseconds() in common.server.ts
- calculateDurationFromStart() in common.server.ts
- recordRunDebugLog() in index.server.ts
- retry event recording in runEngineHandlers.server.ts

The correct pattern (BigInt(ms) * BigInt(1_000_000)) already existed
in convertDateToNanoseconds() in the same file.

Closes #3292
---
 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 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/apps/webapp/app/v3/eventRepository/common.server.ts b/apps/webapp/app/v3/eventRepository/common.server.ts
index 3ba8a50c7f7..5d5d0e201f1 100644
--- a/apps/webapp/app/v3/eventRepository/common.server.ts
+++ b/apps/webapp/app/v3/eventRepository/common.server.ts
@@ -21,7 +21,7 @@ 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 {
@@ -35,7 +35,7 @@ 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 70ea6440321..edc0280baf2 100644
--- a/apps/webapp/app/v3/eventRepository/index.server.ts
+++ b/apps/webapp/app/v3/eventRepository/index.server.ts
@@ -215,7 +215,7 @@ 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 411f91ff75d..aa355cd04dd 100644
--- a/apps/webapp/app/v3/runEngineHandlers.server.ts
+++ b/apps/webapp/app/v3/runEngineHandlers.server.ts
@@ -428,7 +428,7 @@ export function registerRunEngineEventBusHandlers() {
       const eventRepository = resolveEventRepositoryForStore(run.taskEventStore);
 
       await eventRepository.recordEvent(retryMessage, {
-        startTime: BigInt(time.getTime() * 1000000),
+        startTime: BigInt(time.getTime()) * BigInt(1_000_000),
         taskSlug: run.taskIdentifier,
         environment,
         attributes: {