feat(otel): set http.response.status_code on the success SERVER span

[ryan-crabbe-berri]

Summary

The proxy SERVER span (Received Proxy Server Request) only carried http.response.status_code on failures (set in _record_exception_on_span); successful requests had no status-code attribute. This left error-ratio and status-breakdown dashboards with no 2xx denominator and made the span non-compliant with the OTel HTTP semantic conventions (the attribute is required whenever a response is sent, not error-only). This adds a set_response_status_code_attribute helper and calls it from async_post_call_success_hook with 200, symmetric with the failure path and with the route / preprocessing-duration attributes that already land on the success SERVER span. Follow-up to #28040.

Screenshot

Test plan

• tests/test_litellm/integrations/test_opentelemetry.py::TestOpenTelemetrySetResponseStatusCodeAttribute — int-200 on success, None status code omits the attribute, None span is a no-op
• make test-unit slice: 18 tests in the OTel attribute suite (route / preprocessing / server-span / new) pass; Black clean
• Manual: Jaeger all-in-one + proxy with callbacks: ["otel"]; mock-success 200 request → Received Proxy Server Request span carries http.response.status_code=200 alongside http.route, url.path, litellm.preprocessing.duration_ms

[greptile-apps]

Greptile Summary

This PR adds http.response.status_code=200 to the successful proxy SERVER span (Received Proxy Server Request) in the OpenTelemetry integration. Previously the attribute was only set on failure spans via _record_exception_on_span, leaving dashboards with no 2xx denominator and the span non-compliant with OTel HTTP semantic conventions.

• A new set_response_status_code_attribute helper is added, mirroring the pattern of set_proxy_request_route_attributes and set_preprocessing_duration_attribute; it no-ops when span or value is None.
• async_post_call_success_hook calls the helper with 200, symmetric with the failure path.
• Three new unit tests verify the int-200 case, the None-value no-op, and the None-span no-op using in-memory OTel spans only.

Confidence Score: 5/5

Safe to merge — the change is narrowly scoped to adding one telemetry attribute on the success path, with a proper null guard and no mutations to request handling logic.

The helper is a thin wrapper around safe_set_attribute, the null/None guards match the existing pattern, and the call site in async_post_call_success_hook is additive only. Tests are well-targeted in-memory unit tests with no network calls. No existing tests were modified or weakened.

No files require special attention.

Important Files Changed

Filename	Overview
litellm/integrations/opentelemetry.py	Adds set_response_status_code_attribute helper and calls it with 200 in the success hook; symmetrically placed with the failure-path attribute already set in _record_exception_on_span.
tests/test_litellm/integrations/test_opentelemetry.py	Adds three focused unit tests for set_response_status_code_attribute using in-memory spans only; no network calls, consistent with existing test patterns in the file.

_{Reviews (1): Last reviewed commit: "feat(otel): set http.response.status_cod..." | Re-trigger Greptile}

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
litellm/integrations/opentelemetry.py	80.00%	1 Missing ⚠️

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