[MaiAditya]

What does this PR do?

Fixes langfuse/langfuse#20157

EventSerializer now returns <class 'module.QualName'> for class objects instead of dumping their namespace (mappingproxy / descriptor entries) or falling back to a double-quoted string. This is what an @observe-decorated function records for arguments like schema=Invoice. The class check sits after the plain JSON types and before the depth, dataclass, BaseModel, __slots__ and vars() branches; those only handle instances, so nothing else changes. The name is built from __module__ and __qualname__ rather than repr() so a metaclass __repr__ (e.g. Enum classes) can't change it.

It also removes the embedded quotes from the final fallback in default(): the value was "\"<not serializable object of type: X>\"" in the JSON. The encode() fallback, which produces the whole document, keeps its quotes.

Not covered: generic aliases and unions such as list[Invoice] or Invoice | None are not type instances and still go through the existing branches; happy to handle them here or in a follow-up.

Type of change

• Bug fix
• New feature
• Breaking change
• Refactor
• Documentation update
• Tooling, CI, or repo maintenance

Verification

List the main commands you ran:

pytest tests/unit/test_serializer.py tests/unit/test_observe.py   # 72 passed; the 7 new tests fail on main
pytest -n auto tests/unit   # no new failures vs main (prompt/version tests need an installed package and env in my setup)
ruff format --check . && ruff check .
mypy langfuse

Checklist

• I self-reviewed the diff using code_review.md.
• I added or updated tests for behavior changes.
• I updated docs, examples, or .env.template if needed.
• I did not hand-edit generated files; if generated files changed, I used the upstream regeneration path.
• I did not commit secrets or credentials.

Confidence Score: 5/5

The PR appears safe to merge; no actionable issues were found.

Summary

EventSerializer now records class objects as <class 'module.QualName'> instead of walking their fields.

• Observed class arguments appear as readable class references.
• Nested serialization failures leave out extra quote characters.

_{Reviews (2) · Last reviewed commit: "fix(serializer): record class objects as..." · Reviewed by Greptile}

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[CLAassistant]

All committers have signed the CLA.