[Aminark]

What does this PR do?

observe()(partial(fn, ...)) raises AttributeError before calling fn, because partial objects do not have a __name__. This affects both sync and async functions when no observation name is supplied.

Resolve the default name from the wrapped function, including nested partials. Explicit observation names and a partial's own __name__ keep their precedence; the original partial is still used for execution and argument inspection.

Adds six regression cases for sync/async partials, explicit names, and nested partials with or without a custom function name. Four fail on the current main branch.

Type of change

• Bug fix

Verification

uv run --frozen pytest tests/unit/test_observe.py -q
uv run --frozen ruff check .
uv run --frozen ruff format --check langfuse/_client/observe.py tests/unit/test_observe.py
uv run --frozen mypy langfuse --no-error-summary

All 21 observe unit tests pass on Python 3.13. Lint, formatting, and type checks pass. E2E and live-provider tests were not run; these cases use the shared in-memory exporter and do not need a Langfuse server or provider calls.

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 (no changes needed).
• I did not hand-edit generated files.
• I did not commit secrets or credentials.

Confidence Score: 5/5

This PR appears safe to merge.

Summary

Fixes default observation names for partial functions in both sync and async calls.

• Observed partials get a name from the wrapped function.

No actionable issues found.

_{Reviews (1) · Last reviewed commit: "fix(observe): resolve names for partial ..." · Reviewed by Greptile}

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