fix(nextjs): Drop meta trace tags if rendered page is ISR

[logaretm]

Summary

ISR pages will have a sentry-trace and baggage meta tags rendered on them following the initial render or after the first invalidation causing a cached trace id to be present until the next invalidation.

This happens in Next.js 15/16 and both on Turbopack and Webpack.

What I tried and didn't work

I Found no way to conditionally set/unset/change the values set by the clientTraceMetadata option, I found nothing useful on unit async storages, nor re-setting the propagation context works. The clientTraceMetadata gets called way earlier at the app-render.tsx level, which would call our SentryPropagator.inject() then. We cannot intercept it either because it runs before the page wrapper is called.

The main issue is timing:

• Suppressing the tracing wouldn't work either because it is too late. Ideally we want a way to tell Next to remove those attributes at runtime, or render them conditionally.
• I also tried setting everything that has to do with sentry-trace or baggage to dummy values as some sort of "marker" for the SDK on the browser side to drop them, but again it is too late since clientTraceMetadata is picked up too early.

Implementation

so I figured a workaround, I decided to do it on the client side by:

• Marking ISR page routes via the route manifest we already have.
• In Sentry.init call we remove the tags before the browser integration has had a chance to grab the meta tags.

Not the cleanest way, but I verified the issue by writing tests for it and observing page loads across multiple page visits having the same trace id. The meta deletion forces them to have new id for every visit which is what we want.

[linear]

JS-1152 nextjs incremental static rendering causes cached trace id, leading to merged client-side transactions from different users/requests

[github-actions]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	24.6 kB	-	-
@sentry/browser - with treeshaking flags	23.09 kB	-	-
@sentry/browser (incl. Tracing)	41.26 kB	-	-
@sentry/browser (incl. Tracing, Profiling)	45.53 kB	-	-
@sentry/browser (incl. Tracing, Replay)	79.73 kB	-	-
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	69.4 kB	-	-
@sentry/browser (incl. Tracing, Replay with Canvas)	84.42 kB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback)	96.58 kB	-	-
@sentry/browser (incl. Feedback)	41.27 kB	-	-
@sentry/browser (incl. sendFeedback)	29.27 kB	-	-
@sentry/browser (incl. FeedbackAsync)	34.2 kB	-	-
@sentry/react	26.29 kB	-	-
@sentry/react (incl. Tracing)	43.22 kB	-	-
@sentry/vue	29.09 kB	-	-
@sentry/vue (incl. Tracing)	43.03 kB	-	-
@sentry/svelte	24.61 kB	-	-
CDN Bundle	26.9 kB	-	-
CDN Bundle (incl. Tracing)	41.81 kB	-	-
CDN Bundle (incl. Tracing, Replay)	78.33 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback)	83.81 kB	-	-
CDN Bundle - uncompressed	78.84 kB	-	-
CDN Bundle (incl. Tracing) - uncompressed	124 kB	-	-
CDN Bundle (incl. Tracing, Replay) - uncompressed	240.03 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	252.79 kB	-	-
@sentry/nextjs (client)	45.47 kB	+0.28%	+126 B 🔺
@sentry/sveltekit (client)	41.64 kB	-	-
@sentry/node-core	50.86 kB	-0.01%	-1 B 🔽
@sentry/node	158.03 kB	-0.01%	-3 B 🔽
@sentry/node - without tracing	92.73 kB	-0.01%	-2 B 🔽
@sentry/aws-serverless	106.5 kB	-	-

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