[AryanRG]

What does this PR do?

Child events created with parent.start_observation(as_type="event") currently use the ambient span instead of the explicit parent. With no active span, they start a separate trace.

Activate the explicit parent while creating the event, matching the existing child-span and create_event paths. Added coverage for absent, matching and unrelated ambient spans, context restoration and event attributes.

Type of change

• Bug fix

Verification

python -m pytest tests/unit/test_otel.py::test_child_observation_uses_explicit_parent tests/unit/test_resource_manager.py
ruff check .
ruff format --check .
mypy langfuse --no-error-summary

The adjacent OTel/context tests also pass. No live-provider or e2e runs; the change is covered with the in-memory exporter.

Checklist

• I self-reviewed the diff using code_review.md.
• I added tests for the behavior change.
• No docs, examples or environment changes are needed.
• No generated files were hand-edited.
• No secrets or credentials were committed.

Confidence Score: 5/5

The PR appears safe to merge.

Summary

Fixes child events so they use the explicit parent instead of the current active span.

• Child events follow the parent selected by the caller.

No actionable issues found. Tests were reviewed but not run.

_{Reviews (1) · Last reviewed commit: "fix: preserve explicit parent for child ..." · Reviewed by Greptile}

[claude]

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[CLAassistant]

All committers have signed the CLA.

[hassiebp]

THanks a lot for your contribution, @AryanRG !