✨ [RUM-10144] apply context defined just after init to View event generated during init

[BenoitZugmeyer]

Motivation

Usually, context (global/user/account/feature flags etc.) is defined just after calling RUM.init(), which is an issue because events that are generated during init() will not have this context.

This is only problematic for View events: RUM.init() generates a first View event that is missing the context defined right after. It is usually fine, as we can expect a RUM View Update to be generated at some point later. But sometimes no View Update happen for some reason (connectivity error, browser exiting abruptly...). In those cases, it is unexpected that the View isn't including the context.

Changes

This PR fixes this issue by slightly delaying the first View update. It uses Promise.resolve() to schedule a view update in the next micro task. It should not impact reliability as using Promise.resolve().then() to schedule a micro task is not impacted by timers throttling.

Please review commit by commit.

Test instructions

In the sandbox, define a user just after init():

      DD_RUM.init({
        clientToken: 'xxx',
        applicationId: 'xxx',
        ...
      })
      DD_RUM.setUser({ id: 'foo' })

Using the devtools extension, look at individual View events by unchecking Show only the latest View event in the "Events" tab.

When loading the sandbox URL, all View events should contain the @usr.id, even the very first View.

Checklist

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

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.39%. Comparing base (b3ee2b8) to head (2b6121e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3597      +/-   ##
==========================================
+ Coverage   92.37%   92.39%   +0.01%     
==========================================
  Files         323      323              
  Lines        8135     8148      +13     
  Branches     1841     1842       +1     
==========================================
+ Hits         7515     7528      +13     
  Misses        620      620              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	146.84 KiB	146.97 KiB	127 B	+0.08%	✅
Rum Recorder	18.02 KiB	18.03 KiB	9 B	+0.05%	✅
Rum Profiler	4.63 KiB	4.63 KiB	0 B	0.00%	✅
Logs	51.60 KiB	51.60 KiB	0 B	0.00%	✅
Flagging	0 B	935 B	935 B	N/A%	✅
Rum Slim	106.47 KiB	106.52 KiB	50 B	+0.05%	✅
Worker	23.59 KiB	23.59 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base Average Cpu Time (ms)	Local Average Cpu Time (ms)	𝚫
addglobalcontext	0.011	0.006	-0.004
addaction	0.030	0.021	-0.009
addtiming	0.005	0.005	-0.001
adderror	0.020	0.020	-0.000
startstopsessionreplayrecording	0.001	0.001	-0.000
startview	0.008	0.005	-0.003
logmessage	0.027	0.023	-0.005

🧠 Memory Performance

Action Name	Base Consumption Memory (bytes)	Local Consumption Memory (bytes)	𝚫 (bytes)
addglobalcontext	25.24 KiB	27.71 KiB	2.46 KiB
addaction	52.48 KiB	55.40 KiB	2.92 KiB
addtiming	25.73 KiB	25.96 KiB	238 B
adderror	58.13 KiB	59.45 KiB	1.32 KiB
startstopsessionreplayrecording	24.03 KiB	25.09 KiB	1.06 KiB
startview	431.48 KiB	424.01 KiB	-7649 B
logmessage	57.04 KiB	56.85 KiB	-200 B

🔗 RealWorld

[BenoitZugmeyer]

/to-staging

[dd-devflow]

View all feedbacks in Devflow UI.

2025-06-04 16:03:38 UTC ℹ️ Start processing command /to-staging

---

2025-06-04 16:03:48 UTC ℹ️ Branch Integration: starting soon, merge expected in approximately 17m43s (p90)

Commit 2b6121e26e will soon be integrated into staging-23.

---

2025-06-04 16:15:46 UTC ℹ️ Branch Integration: This commit was successfully integrated

Commit 2b6121e26e has been merged into staging-23 in merge commit 6826f9d5e7.

Check out the triggered pipeline on Gitlab 🦊

If you need to revert this integration, you can use the following command: /code revert-integration -b staging-23