[Rajkumar Rangaraj (rajkumar-rangaraj)]

Fix Issue # (no existing issue; found while investigating #3223).

Changes

StartOperation/StopOperation lost or misreported fields set on the operation telemetry. On dispose, OperationHolder only mapped DependencyTelemetry, through ActivityShimMapper, which wrote attribute keys the Azure Monitor exporter doesn't use the way it intended. RequestTelemetry fields and custom Properties were never applied.

Exported envelopes from main, compared with TrackDependency/TrackRequest for the same values:

Scenario	Expected (what Track* gives)	StartOperation on main
Http dependency	data = URL, resultCode = 200	data = null, resultCode = 0
SQL dependency	resultCode = 0	null
Queue Message dependency	type Queue Message, data myqueue	type queue, data = the host, target = the full URL, queue name in a messaging.destination custom dimension
Other dependency types	data set	null
Request	url, responseCode, success as set	url null, responseCode 0, Success = false ignored
Telemetry.Properties	exported	dropped (requests and dependencies)
Every operation	none	stray OperationName custom dimension

Root causes:

• The shim set the old-convention http.method together with new-convention keys (url.full, http.response.status_code). The exporter picks its old-convention HTTP path based on http.method and then reads http.url/http.status_code, so it found neither.
• It wrote messaging.destination instead of messaging.destination.name, and wrote the result code for every dependency type as http.response.status_code.
• StartOperation added an OperationName tag to the activity. It carried state between operations in 2.x, but nothing reads it in 3.x and the exporter emits it as a custom dimension.

Fix (small, contained in the shim):

• ActivityShimMapper now writes the same microsoft.dependency.* / microsoft.request.* override keys that TrackDependency/TrackRequest already use, and only for values that are set.
• It now maps RequestTelemetry (Url, Source, ResponseCode) as well as DependencyTelemetry.
• It copies custom Properties whose keys aren't already on the activity, so tag values seeded into Properties by StartOperation(Activity) can't roll back later instrumentation updates. It sets the status only when Success has a value. A request that never sets Success therefore isn't reported as failed; DependencyTelemetry defaults to Success = true, as before.
• OperationHolder.Dispose calls the request mapping alongside the existing dependency mapping.
• StartOperation no longer adds the OperationName tag, and ActivityExtensions.SetOperationName is removed.
• Because only values that are set are applied, an instrumented activity passed to StartOperation(Activity) keeps the fields the exporter derives from it unless the caller sets them.

Out of scope: item-level Context and operation name. StartOperation still doesn't export an operation name, as on main.

Tests

• Added StartOperationExportTests. It runs StartOperation through the real exporter with a capturing HttpPipelineTransport and asserts on the exported envelopes. It covers dependency fields for Http, SQL, Queue Message and custom types; the StartOperation(T) overload; request url, source, responseCode and success; properties; the StartOperation(Activity) overload with explicitly set fields, with instrumentation updates made after start, and with an untouched instrumented activity; and that no unmapped keys appear in customDimensions. Most fail against main. The two caller-activity guards (the untouched activity and instrumentation updates after start) are expected to pass on main too.
  • It runs in its own collection with parallelization disabled. A tracer provider from a test class running at the same time makes both Azure Monitor samplers add microsoft.sample_rate to the same activity, which throws.
• Updated the TelemetryClientExtensionTests that asserted on the removed OperationName activity tag.
• BASE tests pass locally on net8.0 and net462, except FeatureMetricEmissionHelperTests.ReportsFeaturesSeen. That test also fails on clean main in this environment (it expects unknown and gets vm) and is unrelated. TelemetryClientContextTagsTest.StartOperation_GlobalPropertiesApplied fails intermittently in full-suite runs with a duplicate microsoft.sample_rate exception thrown from ActivitySource.StartActivity, which happens when another test class's tracer provider is active at the same time. It reproduces on pure main (without this PR's tests) and is unrelated.

Checklist

• I ran Unit Tests locally.
• CHANGELOG.md updated with one line description of the fix, and a link to the original issue if available.

For significant contributions please make sure you have completed the following items:

• Design discussion issue #
• Changes in public surface reviewed (no public API changes)

[Copilot]

Copilot review overview

🟡 Changes recommended

The telemetry-object overload still discards an explicitly pre-populated dependency operation name.

Review effort: Balanced
Findings: 1

Open (1)

• Preserve pre-populated dependency operation names · New

What changed in this PR

Aligns StartOperation/StopOperation exports with TrackRequest and TrackDependency.

Changes:

• Reuses shared telemetry-to-activity mapping.
• Removes obsolete shim tags and mapper.
• Adds exporter-level regression tests.

File	Description
CHANGELOG.md	Documents the fix.
TelemetryClientExtensionTests.cs	Updates operation-name assertions.
StartOperationExportTests.cs	Tests exported envelopes.
TelemetryClientExtensions.cs	Enables dispose-time mapping.
TelemetryClient.cs	Extracts shared mapping helpers.
ActivityShimMapper.cs	Removes obsolete mapping.
OperationHolder.cs	Applies telemetry before stopping activities.
ActivityExtensions.cs	Removes the unmapped operation-name tag helper.

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[Copilot]

Copilot review overview

🟡 Changes recommended

Disposal can overwrite activity names and tags updated by instrumentation after StartOperation(Activity).

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Preserve caller activity name changes during telemetry disposal · New
• Test RequestTelemetry source export mapping · New

Resolved since last review (1)

• Preserve pre-populated dependency operation names

[Copilot]

Copilot review overview

🟡 Changes recommended

Property precedence can silently discard explicit edits to properties seeded from caller activities.

Review effort: Balanced
Findings: 1

Open (1)

• Preserve intentional edits to initially seeded telemetry properties · New

Resolved since last review (2)

• Preserve caller activity name changes during telemetry disposal
• Test RequestTelemetry source export mapping

[Copilot]

Copilot review overview

🟢 Approval recommended

The contained mapping changes are consistent with existing Track APIs and are covered by focused end-to-end tests.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Preserve intentional edits to initially seeded telemetry properties