[chalmerlowe]

Problem / Context

To emit consistent error metadata and trace correlation across both GAPIC method wrappers (gapic_v1.method) and transport-level interceptors (_observability), google-api-core needs shared helpers that work identically on wrapped GoogleAPICallError exceptions and raw gRPC RpcError exceptions (before gapic_v1.method's wrap_errors runs):

1. Duplicate Error Attribute & Status Code Extraction: _extract_error_attributes previously lived inside google.api_core.gapic_v1.method, bypassed GoogleAPICallError's public properties, and required callers to invoke exceptions._extract_status_code separately (unwrapping exceptions multiple times per failed RPC). At the L4 gRPC interceptor boundary, failures are still raw grpc.RpcError / grpc.aio.AioRpcError instances whose ErrorInfo details live in trailing_metadata() (grpc-status-details-bin) and whose message comes from exc.details().
2. Trace Context Correlation: Structured error logs require Cloud Logging trace correlation fields (logging.googleapis.com/trace, logging.googleapis.com/spanId, logging.googleapis.com/trace_sampled) extracted from an active OpenTelemetry span without raising if OpenTelemetry is not installed or the span is non-recording.

Solution

• google/api_core/_observability.py:
  • Added has_opentelemetry() with module-level caching to check whether opentelemetry.trace is importable.
  • Added extract_trace_context(span=None) to extract trace_id (32-char lowercase hex), span_id (16-char lowercase hex), and trace_sampled (bool) from an explicit or active OpenTelemetry span.
  • Added build_telemetry_error_attributes(exc, status_code=None, status_message=None, include_exception=False) to unwrap chained exceptions once, resolve rpc.response.status_code via exceptions._extract_status_code, and extract error.type, status.message, gcp.errors.domain, gcp.errors.metadata.*, and optional exception.* fields using GoogleAPICallError properties or raw gRPC RpcError trailing metadata (google.rpc.status_pb2.Status).
• google/api_core/gapic_v1/method.py:
  • Replaced local _extract_error_attributes implementation and separate _extract_status_code call with a single call to _observability.build_telemetry_error_attributes.
• Unit Tests:
  • Updated tests/unit/gapic/test_method.py and added unit tests in tests/unit/test_observability.py achieving 100% line and branch coverage across all new helpers.

[gemini-code-assist]

Code Review

This pull request centralizes and enhances telemetry and error attribute extraction by introducing has_opentelemetry, extract_trace_context, and _build_telemetry_error_attributes helpers in _observability.py, replacing the redundant _extract_error_attributes implementation in method.py, and adding comprehensive unit tests. However, a critical issue was identified in _observability.py where exceptions._extract_status_code is called with an unsupported default keyword argument, which will cause a TypeError at runtime; this should be resolved using a logical or fallback instead.

[chalmerlowe]

NOTE: To reviewer: we are moving the _extract_error_attributes() function out of method.py and into _observability.py because it is primarily focused on building out span attributes. The new function is renamed: build_telemetry_error_attributes()