feat: Associate JSErrors and AjaxRequest to extended soft nav interactions

[cwli24]

JavascriptError and AjaxRequest events will be correctly tied to BrowserInteraction when long tasks do/does not happen and extend the interaction. Ultimately, events that start before the final end time of an interaction will be associated to it, inclusive of long tasks.

Overview

(3 of 3 modifying soft navigation heuristic.) During the waiting window of an interaction monitoring for long tasks, JS errors and network requests still occur, and will initially be associated with the interaction that's "pending finish". In the event that there's ultimately no long task, those jse & ajax falling within this window are freed from ixn association and returned to their standalone features. On contrary, if a long task does occur which extends the interaction, they too will become part of the interaction. In other words, association remains faithful to the final time span of the interaction.

Related Issue(s)

https://new-relic.atlassian.net/browse/NR-438511
https://new-relic.atlassian.net/browse/NR-452609

Testing

[github-actions]

Supportability Metric Usage Changes:

No matching changes found

Supportability Metrics .md File Changes:

supportability_metrics.md was changed? false

New supportability metrics require changes to supportability_metrics.md, as well as a new PR to Angler. Please ensure an Angler PR is created and linked to this PR.

[github-actions]

Asset Size Report

Merging this pull request will result in the following asset size changes:

Agent	Asset	Previous Size	New Size	Diff
lite	loader	25.9 kB / 9.76 kB (gzip)	25.9 kB / 9.75 kB (gzip)	0% / -0.04% (gzip)
lite	async-chunk	54.49 kB / 18.02 kB (gzip)	54.5 kB / 18.03 kB (gzip)	0.02% / 0.04% (gzip)
pro	loader	54.02 kB / 19.03 kB (gzip)	54.06 kB / 19.06 kB (gzip)	0.07% / 0.15% (gzip)
pro	async-chunk	92.76 kB / 28.7 kB (gzip)	92.95 kB / 28.79 kB (gzip)	0.21% / 0.31% (gzip)
spa	loader	62.78 kB / 21.74 kB (gzip)	62.91 kB / 21.8 kB (gzip)	0.2% / 0.29% (gzip)
spa	async-chunk	117.34 kB / 35.68 kB (gzip)	118.95 kB / 36.04 kB (gzip)	1.37% / 1% (gzip)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.37%. Comparing base (8a895da) to head (ac3fce5).
⚠️ Report is 1 commits behind head on sn-lt-ajax.

Additional details and impacted files

@@              Coverage Diff               @@
##           sn-lt-ajax    #1554      +/-   ##
==============================================
+ Coverage       87.71%   88.37%   +0.66%     
==============================================
  Files             201      201              
  Lines            7799     7805       +6     
  Branches         1591     1593       +2     
==============================================
+ Hits             6841     6898      +57     
+ Misses            825      787      -38     
+ Partials          133      120      -13     

Flag	Coverage Δ
unit-tests	80.86% <100.00%> (+1.46%)	⬆️

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[github-actions]

Last ran on August 26, 2025 18:15:11 CDT
Checking merge of (ac3fce5) into sn-lt-ajax (8a895da)