Align observability telemetry with OTel SemConv 1.39 and design

[haphungw]

This issue tracks ongoing updates and cleanups to align our client libraries' observability telemetry with OpenTelemetry Semantic Conventions v1.39, as well as necessary adjustments from the latest internal design decisions.

1. Update to OTel SemConv 1.39 (Feb 11, 2026)

• rpc.system → [moved] rename to rpc.system.name
• rpc.service → [deleted] remove attribute entirely
• rpc.method → [modified] fully-qualified including $serviceName/$method
• grpc.status → [moved] replace with rpc.response.status_code string representation.
• rpc.grpc.status_code → [deleted] remove the legacy custom integer attribute.

2. March 3, 2026

• gcp.resource.name → [moved] replaced with gcp.resource.destination.id
• gcp.resource.destination.location → [new] the "location" of the resource if not in the resource name
• gcp.resource.source.controller.id → [new] the "controller" of the resource if known

3. March 17, 2026

• Meta Renames:
  • M1 → M3 to align with T3 span.
  • L1 → L4 to align with T4 span.
• Log Level: L4 (formerly L1) details should be logged at the DEBUG level.
• Typos: Apply fixes for gcp.error.domain → gcp.errors.domain and gcp.error.metadata → gcp.errors.metadata.

4. March 23, 2026

• gcp.client.language → [removed] already present within standard OTel telemetry.sdk.language.
• Instrumentation Name → [added] the instrumentation name should be the artifact name.

[coryan]

Do all of these need to happen before the next release or can they wait until after Cloud Next?

[haphungw]

Most of these are already implemented, but I’m doing a final sweep.

Do all of these need to happen before the next release or can they wait until after Cloud Next?

Based on @westarle's update, gcp.resource.destination.location and gcp.resource.source.controller.id can wait.