chore: better fallback

[metal-messiah]

Take 2 on improving the fallback behavior

Overview

Validated success in NR1 dev this time.

Related Issue(s)

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]

Last ran on June 16, 2026 11:49:23 CDT
Checking merge of (8145bdf) into main (58663ec)

[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	26.79 kB / 10.24 kB (gzip)	26.79 kB / 10.24 kB (gzip)	0% / 0% (gzip)
lite	async-chunk	58.92 kB / 19.76 kB (gzip)	58.92 kB / 19.76 kB (gzip)	0% / 0% (gzip)
pro	loader	66.61 kB / 23.46 kB (gzip)	66.71 kB / 23.5 kB (gzip)	0.14% / 0.15% (gzip)
pro	async-chunk	96.37 kB / 30.65 kB (gzip)	96.37 kB / 30.65 kB (gzip)	0% / 0% (gzip)
spa	loader	69.01 kB / 24.24 kB (gzip)	69.1 kB / 24.28 kB (gzip)	0.13% / 0.17% (gzip)
spa	async-chunk	108.52 kB / 33.76 kB (gzip)	108.52 kB / 33.76 kB (gzip)	0% / 0% (gzip)

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.47%. Comparing base (58663ec) to head (30957e1).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/features/ajax/instrument/index.js	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1795      +/-   ##
==========================================
+ Coverage   89.45%   89.47%   +0.01%     
==========================================
  Files         213      213              
  Lines        7864     7864              
  Branches     1657     1657              
==========================================
+ Hits         7035     7036       +1     
+ Misses        746      745       -1     
  Partials       83       83              

Flag	Coverage Δ
unit-tests	84.80% <80.00%> (+0.01%)	⬆️

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