Update UnbrandedGeneratorVersion to 1.0.0-alpha.20260914.4

[azure-sdk-automation]

This PR updates the UnbrandedGeneratorVersion property in eng/centralpackagemanagement/Directory.Generation.Packages.props and the @typespec/http-client-csharp dependency in eng/packages/http-client-csharp/package.json to version 1.0.0-alpha.20260914.4.

Details

• TypeSpec commit that triggered this PR: microsoft/typespec@b919c54
• Pipeline run that produced this PR: https://dev.azure.com/azure-sdk/internal/_build/results?buildId=6833307&view=results

Changes

• Updated eng/centralpackagemanagement/Directory.Generation.Packages.props UnbrandedGeneratorVersion property
• Updated eng/packages/http-client-csharp/package.json dependency version
• Ran npm install to update package-lock.json
• Ran eng/packages/http-client-csharp/eng/scripts/Generate.ps1 to regenerate test projects
• Generated emitter-package.json artifacts using tsp-client
• Regenerated SDK libraries using the unbranded emitter via dotnet msbuild /t:GenerateCode

This is an automated PR created by the TypeSpec publish pipeline.

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[Copilot]

🔵 Needs a closer look

The dependency bump produces broad generated-code changes across several SDK packages that warrant final human and CI validation.

Pull request overview

Updates the unbranded C# generator and regenerates affected SDK sources.

Changes:

• Bumps generator dependencies to 1.0.0-alpha.20260914.4.
• Regenerates model deserializers to use GetUtf8Bytes().
• Reorders generated derived-type documentation.

File summaries

File	Description
eng/centralpackagemanagement/Directory.Generation.Packages.props	Updates the central generator version.
eng/packages/http-client-csharp/package.json and lock file	Updates the npm dependency and resolution.
eng/http-client-csharp-emitter-package*.json	Updates generated emitter package metadata.
eng/packages/http-client-csharp/generator/TestProjects/Local/Basic-TypeSpec/.../ThingModel.Serialization.cs	Regenerates BinaryData deserialization.
sdk/ai/Azure.AI.Projects/src/Generated/Models/*	Regenerates Projects models and derived-type documentation.
sdk/ai/Azure.AI.Projects.Agents/src/Generated/Models/*	Regenerates Agents models and derived-type documentation.
sdk/ai/Azure.AI.Extensions.OpenAI/src/Generated/Models/*	Regenerates OpenAI extension models.
sdk/transcription/Azure.AI.Speech.Transcription/src/Generated/Models/*	Regenerates transcription models.

Review details

• Files reviewed: 6/476 changed files
• Comments generated: 0
• Review effort level: Balanced

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[Jorge Rangel (jorgerangel-msft)]

Copilot we have some failing tests. Validate what tests are failing, and update any of the testdata to reflect the changes that were made pertaining to the upgraded generator version :

Passed!  - Failed:     0, Passed:    18, Skipped:     0, Total:    18, Duration: 347 ms - TestProjects.Local.Tests.dll (net10.0)
  Azure.Generator.StubLibrary -> /mnt/vss/_work/1/s/artifacts/bin/Azure.Generator.StubLibrary/Debug/net10.0/Azure.Generator.StubLibrary.dll
  Copying output to dist path
  Copying output to dist path
  Failed ConverterModelE2E [40 ms]
  Error Message:
     Expected string length 10482 but was 10446. Strings differ at index 8619.
  Expected: "...DataProperties.Add(prop.Name, global::System.BinaryData.Fr..."
  But was:  "...DataProperties.Add(prop.Name, prop.Value.GetUtf8Bytes());\n..."

[Copilot]

Copilot we have some failing tests. Validate what tests are failing, and update any of the testdata to reflect the changes that were made pertaining to the upgraded generator version :

Updated the ConverterModelE2E testdata baseline to expect prop.Value.GetUtf8Bytes() in commit aafbb62. The targeted test and full generator suite pass, along with regeneration, lint, and formatting checks. The separate Confidential Ledger failures are live-service 503 responses and unrelated to this generator update.

[Jorge Rangel (jorgerangel-msft)]

Failing tests are unrelated to these changes. Overriding.