Force-flush trace spans before the A2A response completes for substrate

[iplay88keys]

Description

On Agent Substrate, the session actor is gVisor-checkpointed as soon as the A2A response body closes. Spans still buffered in the SDK's BatchSpanProcessor (default ~5s flush interval) freeze into the snapshot and only export when the session is next resumed — so a session's last message never produces a trace, and every other message's trace is delayed until the next chat. Both ADK executors now force-flush the tracer provider before the response completes.

Go ADK

• New telemetry.ForceFlush(ctx): flushes the global tracer provider's batch processor with a detached 3s timeout (the request context is already canceled when deferred cleanup runs); no-op for providers without ForceFlush (tracing disabled).
• a2a/executor.go calls it in the execute defer, after the root invocation span ends so the root span is included in the flush.

Python ADK

• New kagent.core.tracing.force_flush(timeout_millis=3000): no-op when the provider has no force_flush; exporter errors are logged, never raised.
• _agent_executor.py calls it in a finally on execute() via asyncio.to_thread, so the blocking gRPC export cannot stall the event loop.

A collector outage costs at most one bounded 3s flush per invocation, after response events are already published — it never adds user-visible chat latency.

Also included: the grafana-mcp and querydoc helm image helpers now append the optional image.name segment when set (compact drops it when absent, so charts using the default two-segment registry/repository values render unchanged).

[Copilot]

Pull request overview

This PR ensures OpenTelemetry spans are force-flushed before an A2A response completes on Agent Substrate (to avoid buffered spans being checkpoint-frozen and exported only on the next resume), and updates Helm helper templates to optionally include an image.name segment when constructing image references.

Changes:

• Add Go telemetry.ForceFlush(ctx) and invoke it after the root invocation span ends in the Go A2A executor.
• Add Python kagent.core.tracing.force_flush() and invoke it at the end of the Python ADK executor via asyncio.to_thread to avoid blocking the event loop.
• Update grafana-mcp and querydoc Helm image helpers to include an optional image.name segment in the image path.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
python/packages/kagent-core/tests/test_tracing_configure.py	Adds unit tests for the new Python tracing force-flush helper behavior.
python/packages/kagent-core/src/kagent/core/tracing/_utils.py	Introduces force_flush() to flush buffered spans with a bounded timeout and swallow exporter errors.
python/packages/kagent-core/src/kagent/core/tracing/init.py	Exports force_flush from the tracing package public API.
python/packages/kagent-adk/src/kagent/adk/_agent_executor.py	Calls tracing force-flush in execute() cleanup using asyncio.to_thread.
helm/tools/querydoc/templates/_helpers.tpl	Extends image reference construction to include optional image.name.
helm/tools/grafana-mcp/templates/_helpers.tpl	Extends image reference construction to include optional image.name.
go/adk/pkg/telemetry/tracing.go	Adds ForceFlush helper that detaches from request cancellation and flushes spans with a 3s timeout.
go/adk/pkg/telemetry/tracing_test.go	Adds test ensuring buffered spans are exported on flush and that no-op providers don’t panic.
go/adk/pkg/a2a/executor.go	Flushes spans after ending the invocation span in deferred executor cleanup.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.