Python: expose message event control through enable_instrumentation

[Eduard van Valkenburg (eavanvalkenburg)]

Motivation & Context

Microsoft OpenTelemetry Distro configures OpenTelemetry providers and exporters externally, but it cannot currently disable Agent Framework's baseline GenAI message events through the public instrumentation-only API. Calling enable_instrumentation(enable_message_events=False) raises an unexpected-keyword TypeError.

This adds the remaining Python API control without transferring provider ownership or changing sensitive-data defaults.

Description & Review Guide

• What are the major changes? Add the keyword-only enable_message_events: bool | None = None option to enable_instrumentation, cover explicit/omitted, environment, sticky-disable/force, provider-preservation, and emission behavior, and document third-party provider usage.
• What is the impact of these changes? Explicit booleans update the existing baseline message-event setting; omitted or None preserves its current value. Existing sensitive-data gating, experimental message span attributes, spans, metrics, and externally configured providers/exporters remain unchanged.
• What do you want reviewers to focus on? Confirm that omitted-value preservation and the sticky-disable/force behavior match the existing instrumentation contract.

Related Issue

Fixes #8443

Partially addresses #8412. The .NET investigation remains tracked by #8444.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

🟢 Approval recommended

The implementation matches the stated contract and includes comprehensive focused tests.

Pull request overview

Adds programmatic message-event control to Python instrumentation while preserving provider ownership and existing defaults.

Changes:

• Adds enable_message_events to enable_instrumentation.
• Covers precedence, sticky-disable, provider preservation, and telemetry emission.
• Documents third-party provider usage.

File summaries

File	Description
python/packages/core/agent_framework/observability.py	Implements the new option.
python/packages/core/tests/core/test_observability.py	Adds regression coverage.
python/samples/02-agents/observability/README.md	Documents configuration behavior.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Balanced

---

💡 Add a code-review agent skill for context-aware, tailored reviews. Learn more in the docs.

[github-actions]

MAF Automated Review — Iteration 1

Result: No findings
Scope: full PR (1 commit(s)): f27b3f449365
Model: gpt-5.6-sol-fast

Overview

This PR adds an additive keyword-only control for baseline GenAI message events while preserving the current setting when the argument is omitted or None. The implementation retains the existing sticky-disable, sensitive-data, and provider-ownership guardrails, and the expanded tests cover explicit overrides, state preservation, provider identity, and streaming and non-streaming emission. No publishable Critical, High, or Medium issue was established.

Reviewed the supplied pull-request change set across correctness, security/reliability, architecture, and failure behavior.
No publishable findings remained after source verification for this scope.