Structured logs include replay_id when replay is not sampled

Is there an existing issue for this?

I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
I have reviewed the documentation https://docs.sentry.io/
I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/react

SDK Version

10.12.0

Framework Version

No response

Link to Sentry event

No response

Reproduction Example/SDK Setup

No response

Steps to Reproduce

Structured logs are showing a replay_id even when the replay was not sampled due to replaysOnErrorSampleRate. This causes confusion since the replay can’t be found in Sentry.

Configure SDK with replaysOnErrorSampleRate: 0.2 (or any low sample rate).
Trigger an error in the app that incudes logs
Notice that a replay_id tag is in the logs even when the replay was not actually captured / attatched to the error due to replaysOnErrorSampleRate

example issue here where logs include a replay_id but no replay is associated with the error or found in replays search

Expected Result

If a replay isn’t sampled and won’t be sent to Sentry, the associated error/log should not include a replay_id

Actual Result

Structured logs still contain a replay_id, even when the replay is skipped due to sampling. This creates confusion for users who try to search for the replay in Sentry but can’t find it.

Additional Context

_{Tip: React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.}

JS-950 Structured logs include replay_id when replay is not sampled

Thanks for reporting! I can see how this is confusing. Thing is right now, it's not super easy to check if the replay was sampled positively or negatively. After a quick check, we could probably only return an id here,

sentry-javascript/packages/replay-internal/src/replay.ts

Lines 723 to 725 in 6e8e561

    
           public getSessionId(): string | undefined { 
        
             return this.session?.id; 
        
           }

if the session was sampled (or rather, return undefined if !sampled. Thoughts @AbhiPrasad, @chargome, @billyvg?

Not sure if this wouldn't interfere with manually started replays 🤔

I quickly checked this when replying and it seems like manually started replay sessions are started with sessionSampleRate: 1. Though this is just my naive assumption, maybe there's more to this that I'm not aware of.

I'd be open to adjust getSessionId to only run if sampled, but not sure if there are other consequences here.

I could move the logging related code into the replay integration, let me open up a PR to show this as an example.

Don't think we can change it because we rely on the id before the session itself is marked as sample (though my brain is a bit foggy atm coming back from sabbatical).

	public getSessionId(): string \| undefined {
	return this.session?.id;
	}