From 9d2f1389e4b7ce6196ee0bc6af0db716482fdbda Mon Sep 17 00:00:00 2001
From: Marceli Pawlinski <marceli@pawlinski.pl>
Date: Sun, 26 Jul 2026 04:01:19 +0100
Subject: [PATCH] fix(webapp): prevent OTLP nanosecond timestamp overflow
 (#3292)

Move BigInt() before multiplication to avoid IEEE 754 precision loss
when converting epoch milliseconds to nanoseconds.

Fixes 4 overflow sites:
- getNowInNanoseconds(): BigInt(Date.now()) * 1_000_000n
- calculateDurationFromStart(): BigInt(getTime()) * 1_000_000n
- recordEvent() startTime: BigInt(getTime()) * 1_000_000n
- runEngineHandlers OOM retry: BigInt(getTime()) * 1_000_000n

Also adds epochMsToNanoseconds() helper to durations.ts for safe
epoch-level conversions, and fixes seed script consistency.
---
 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 +-
 apps/webapp/seed-ai-spans.mts                       | 2 +-
 packages/core/src/v3/utils/durations.ts             | 5 +++++
 5 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/apps/webapp/app/v3/eventRepository/common.server.ts b/apps/webapp/app/v3/eventRepository/common.server.ts
index eb8bf7f23ec..b2da1b0cecc 100644
--- a/apps/webapp/app/v3/eventRepository/common.server.ts
+++ b/apps/webapp/app/v3/eventRepository/common.server.ts
@@ -25,7 +25,7 @@ export function extractContextFromCarrier(carrier: Record<string, unknown>) {
 }
 
 export function getNowInNanoseconds(): bigint {
-  return BigInt(new Date().getTime() * 1_000_000);
+  return BigInt(Date.now()) * 1_000_000n;
 }
 
 export function getDateFromNanoseconds(nanoseconds: bigint): Date {
@@ -39,7 +39,7 @@ 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()) * 1_000_000n - 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 f0687d2a7ce..e8ff68be6f8 100644
--- a/apps/webapp/app/v3/eventRepository/index.server.ts
+++ b/apps/webapp/app/v3/eventRepository/index.server.ts
@@ -240,7 +240,7 @@ async function recordRunEvent(
         runId: foundRun.friendlyId,
         ...attributes,
       },
-      startTime: BigInt((startTime?.getTime() ?? Date.now()) * 1_000_000),
+      startTime: BigInt(startTime?.getTime() ?? Date.now()) * 1_000_000n,
       ...optionsRest,
     });
 
diff --git a/apps/webapp/app/v3/runEngineHandlers.server.ts b/apps/webapp/app/v3/runEngineHandlers.server.ts
index c44bcc54cec..f03a24e47ed 100644
--- a/apps/webapp/app/v3/runEngineHandlers.server.ts
+++ b/apps/webapp/app/v3/runEngineHandlers.server.ts
@@ -555,7 +555,7 @@ export function registerRunEngineEventBusHandlers() {
         );
 
         await eventRepository.recordEvent(retryMessage, {
-          startTime: BigInt(time.getTime() * 1000000),
+          startTime: BigInt(time.getTime()) * 1_000_000n,
           taskSlug: run.taskIdentifier,
           environment,
           attributes: {
diff --git a/apps/webapp/seed-ai-spans.mts b/apps/webapp/seed-ai-spans.mts
index 5297171f955..dd9773ed097 100644
--- a/apps/webapp/seed-ai-spans.mts
+++ b/apps/webapp/seed-ai-spans.mts
@@ -474,7 +474,7 @@ function buildAiSpanTree(params: SpanTreeParams): CreateEventInput[] {
     attemptNumber?: number;
   }): CreateEventInput {
     const startNs = BigInt(opts.startMs) * BigInt(1_000_000);
-    const durationNs = opts.durationMs * 1_000_000;
+    const durationNs = BigInt(opts.durationMs) * BigInt(1_000_000);
     return {
       traceId,
       spanId: opts.spanId,
diff --git a/packages/core/src/v3/utils/durations.ts b/packages/core/src/v3/utils/durations.ts
index d1290d93044..5aed38aece2 100644
--- a/packages/core/src/v3/utils/durations.ts
+++ b/packages/core/src/v3/utils/durations.ts
@@ -32,6 +32,11 @@ export function millisecondsToNanoseconds(milliseconds: number): number {
   return milliseconds * 1_000_000;
 }
 
+/** Convert epoch milliseconds to nanoseconds using BigInt to avoid overflow. */
+export function epochMsToNanoseconds(ms: number): bigint {
+  return BigInt(ms) * 1_000_000n;
+}
+
 export function formatDurationNanoseconds(nanoseconds: number, options?: DurationOptions): string {
   return formatDurationMilliseconds(nanosecondsToMilliseconds(nanoseconds), options);
 }