# Description
This change removes the remaining `TraceConfiguration`-driven
apply/setter API path and aligns configuration startup with the 2.0
telemetry model (`ITelemetryContext`/`ILoggerFactory`). It also updates
migration docs to make the removal explicit and actionable.
- **Core API removals**
- Deleted `TraceConfiguration.ApplySettings()` implementation file.
- Removed runtime apply calls from configuration/server startup paths.
- Removed fluent builder trace setters:
- `SetOutputFilePath(...)`
- `SetDeleteOnLoad(...)`
- `SetTraceMasks(...)`
- Simplified builder interface inheritance accordingly.
- **Call-site and test fixture updates**
- Removed usage of deleted trace fluent APIs in affected test
infrastructure and fixtures.
- Updated GDS log readers to tolerate missing `TraceConfiguration`
output path safely.
- **Migration guidance**
- Updated migration docs to explicitly state removal of
`TraceConfiguration` apply APIs and direct users to telemetry-based
logging configuration.
```csharp
// Removed API pattern
app.Build(uri, product)
.AsClient()
.SetOutputFilePath("trace.log")
.SetTraceMasks(Utils.TraceMasks.Error);
// New direction
// Configure logging via ITelemetryContext / ILoggerFactory at composition/startup.
```
## Related Issues
- OPCFoundation/UA-.NETStandard#4091
## Checklist
- [ ] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf)
and read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [ ] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added all necessary documentation.
- [ ] I have verified that my changes do not introduce (new) build or
analyzer warnings.
- [ ] I ran **all** tests locally using the **UA.slnx** solution against
at least .net **framework** and .net **10**, and all passed.
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.
<!-- START COPILOT CODING AGENT SUFFIX -->
- Fixes#4091
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
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