🐛 Fix action <-> long task correlation

[amortemousque]

Motivation

When a click handler runs longer than 50 ms, it creates a long task. Before this fix, the RUM long task was not linked to the RUM action because the action used clocksNow() instead of event.timeStamp. As a result, long_task.startTime was earlier than action.startTime. After the fix, long_task.startTime is later than action.startTime, which allows proper
correlation.

Increase by 6× the number of long tasks correlated with a click in the Datadog UI.
Query: @long_task.scripts.invoker:click @action.id:*

Changes

• Use startEvent.timeStamp for the RUM action startTime

Test instructions

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.

[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	164.33 KiB	164.34 KiB	+11 B	+0.01%	✅
Rum Profiler	4.32 KiB	4.32 KiB	0 B	0.00%	✅
Rum Recorder	19.74 KiB	19.74 KiB	0 B	0.00%	✅
Logs	56.14 KiB	56.14 KiB	0 B	0.00%	✅
Flagging	944 B	944 B	0 B	0.00%	✅
Rum Slim	121.61 KiB	121.62 KiB	+11 B	+0.01%	✅
Worker	23.63 KiB	23.63 KiB	0 B	0.00%	✅

🚀 CPU Performance

Pending...

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	26.34 KiB	25.93 KiB	-418 B
RUM - add action	48.80 KiB	48.60 KiB	-211 B
RUM - add timing	24.90 KiB	24.47 KiB	-438 B
RUM - add error	54.02 KiB	54.24 KiB	+219 B
RUM - start/stop session replay recording	23.71 KiB	24.50 KiB	+815 B
RUM - start view	425.08 KiB	423.29 KiB	-1.79 KiB
Logs - log message	43.26 KiB	43.86 KiB	+617 B

🔗 RealWorld

[datadog-official]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage
• Patch Coverage: 100.00%
• Overall Coverage: 92.68% (+0.01%)

View detailed report

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[thomasbertet]

So nice to see the correlation improvement! Code changes LGTM!