fix(llmobs): prevent config origin overwrite in enable()

[watson]

What does this PR do?

Fixes a bug in the LLMObs SDK's enable() method where configuration origins were being incorrectly tracked for telemetry:

• Pass only the llmobs config object to configure() to avoid spreading the entire config
• Remove unnecessary intermediate variables in both config.js and sdk.js
• Invert early-return logic in sdk.js for clearer control flow
• Add TODO comment noting that calling configure() from enable() still sets origin as 'code' even when enable() is called from Remote Config updates

Motivation

The enable() method in packages/dd-trace/src/llmobs/sdk.js was spreading the entire _config object when calling configure():

this._config.configure({ ...this._config, llmobs: llmobsConfig })

This caused all configuration values to be re-set with origin 'code', overwriting their actual origins (e.g. 'env', 'default', etc.). This breaks telemetry tracking which relies on accurate origin information to understand how users are configuring the tracer.

Additional Notes

I've done my best to ensure that it's ok to call configure with only a sub-set of config options and that it will still work even if #applyOptions was called previously with another sub-set of options. But this is important to review!

There's still a remaining issue (noted in the TODO): when enable() is called based on APM_TRACING RC product updates, the config telemetry will show origin as 'code' rather than the actual source (whatever that should actually be?).

[watson]

• fix(llmobs): prevent config origin overwrite in enable() #7183 👈 (View in Graphite)
• master

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[github-actions]

Overall package size

Self size: 4.39 MB
Deduped: 5.21 MB
No deduping: 5.21 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | import-in-the-middle | 2.0.0 | 68.46 kB | 797.03 kB | | dc-polyfill | 0.1.10 | 26.73 kB | 26.73 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-01-06 21:09:53

Comparing candidate commit 8baa329 in PR branch watson/clean-up-llmobs-enable with baseline commit 2681a5e in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 293 metrics, 27 unstable metrics.

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.52%. Comparing base (2681a5e) to head (8baa329).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/dd-trace/src/llmobs/sdk.js	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7183      +/-   ##
==========================================
+ Coverage   84.51%   84.52%   +0.01%     
==========================================
  Files         525      525              
  Lines       22492    22488       -4     
==========================================
- Hits        19008    19007       -1     
+ Misses       3484     3481       -3     

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[sabrenner]

thanks for catching this! tbh the code in sdk for this enablement is from a misguided early on approach of mirroring our Python implementation, which does need an enable method to call as it is its own module, but totally not needed here, and in our docs we only ever show enablement through init.

The idea is in v6 we'll remove these methods (reminds me that I need to add a deprecation log), so hopefully this just won't be an issue at that point, but again thank you for catching this in the meantime!

also thanks for the minor cleanups, definitely makes sense 😄

[BridgeAR]

While this already improves things very slightly, it does not seem to fix the overall issue that config things should not be handled outside of config.