✨ [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.

Fixes #3935

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).
⚠️ Report is 587 commits behind head on main.

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	180.58 KiB	180.68 KiB	+98 B	+0.05%	✅
Rum Profiler	8.43 KiB	8.43 KiB	0 B	0.00%	✅
Rum Recorder	21.12 KiB	21.12 KiB	0 B	0.00%	✅
Logs	57.03 KiB	57.03 KiB	0 B	0.00%	✅
Rum Salesforce	N/A	138.49 KiB	N/A	N/A	N/A
Rum Slim	138.46 KiB	138.48 KiB	+18 B	+0.01%	✅
Worker	22.96 KiB	22.96 KiB	0 B	0.00%	✅
Rum Shopify	N/A	200.25 KiB	N/A	N/A	N/A
Rum-shopify Profiler	N/A	8.43 KiB	N/A	N/A	N/A
Rum-shopify Recorder	N/A	3.72 KiB	N/A	N/A	N/A

[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

[datadog-datadog-prod-us1]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 90.91%
• Overall Coverage: 77.21% (+0.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 1f18c98 | Docs | Datadog PR Page | Give us feedback!}

[BenoitZugmeyer]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 303932c962

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Preserve the deferred refresh after synchronous view updates

issue: When another API emits the active view synchronously before this microtask—most notably setViewName()—the documentVersion === 0 guard suppresses the deferred update. For example, init(); setViewName('checkout'); setUser({ id: '123' }) sends the first view before the user is set and then may never send a corrected view because changing user/global/feature-flag context does not itself schedule one. The deferred callback should only be skipped when the view has ended, or otherwise still emit an update that incorporates the rest of the same-task context calls.

Useful? React with 👍 / 👎.

[BenoitZugmeyer]

It's probably fine, setViewName usage is a bit niche, and fixing makes things a bit more complex: it means introducing yet another lifecycle event to signal that a view is about to be updated, so we can the new view name without waiting for the deferred promise.