Add Regen Preview Pipeline for azure-sdk-for-net preview PRs

[Copilot]

Implementation Complete ✅

• Create the regen-preview.yaml pipeline file in packages/http-client-csharp/eng/pipeline/
  • Configure as manual-only trigger (no automatic triggers)
  • Add parameters for library type selection (All, Unbranded, Azure, Mgmt)
  • Set up stages to build packages, clone azure-sdk-for-net, run RegenPreview.ps1
  • Configure artifact upload for regen-report.json
  • Set up PR creation against azure-sdk-for-net repository
  • Handle success/failure scenarios with appropriate PR titles and labels
  • Display failed library regeneration details in pipeline output with safe error handling
• Test the pipeline configuration syntax
• Verify all required scripts and modules are available
• Review and validate the implementation
• Fix label name to match issue requirements
• Address PR feedback
  • Create dedicated Submit-RegenPreviewPr.ps1 script following Submit-AzureSdkForNetPr.ps1 pattern
  • Remove "DO NOT MERGE" statement from PR body
  • Remove "Library type regenerated" bullet from PR body
  • Remove "Artifacts" section from PR body
  • Use gh CLI for PR creation following established pattern
  • Remove unnecessary Update-PackageJson.ps1 step (RegenPreview.ps1 handles package building)
  • Remove unnecessary tsp-client installation step (RegenPreview.ps1 installs it)
  • Update PR title format to show failure status as prefix: "(Failed) Regen Preview: ..."
  • Make PR body dynamic based on selected library type (shows appropriate package names)
  • Stage only sdk/ folder changes instead of all repository changes
  • Remove unnecessary git config commands (pipeline handles git setup)
  • Parse and display failed library details from regen-report.json in pipeline output
  • Add safe error handling to prevent report parsing failures from failing the build

Summary

Created a new Azure DevOps pipeline (regen-preview.yaml) with dedicated PowerShell script (Submit-RegenPreviewPr.ps1) that provides a manual workflow for regenerating libraries in azure-sdk-for-net and creating preview PRs.

The pipeline relies on RegenPreview.ps1 to handle all package building and dependency management from source. The generated PR title dynamically shows failure status as a prefix (e.g., "(Failed) Regen Preview: ...") and the PR body displays the specific package names based on the selected library type. Only changes in the sdk/ folder are staged for the preview PR. The script follows the same pattern as Submit-AzureSdkForNetPr.ps1.

The pipeline includes a step that safely parses the regen-report.json file and displays detailed information about any failed library regenerations directly in the pipeline output. The step uses $ErrorActionPreference = 'Continue' and wraps all logic in a try-catch block to ensure parsing errors don't fail the build. If parsing fails, a warning is displayed and users are directed to the artifact. This makes it easier to diagnose issues without downloading the artifact, while ensuring the pipeline remains resilient.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add Regen Preview Pipeline</issue_title>
<issue_description>As a follow up to Azure/azure-sdk-for-net#52234, we ended up creating a script to run as part of our local workflows. It would be great if we could add a manual / optional validation to our PR workflows that would trigger this script and output the diffs in the generated code.

At a minimum, the pipeline should allow regenerated all library types (unbranded, azure, mgmt). Optimally, it would allow choosing which type of library to regenerate. It should open a draft PR against the https://github.com/Azure/azure-sdk-for-net repo to view the diffs in the generated code. The draft PR title should be "Regen Preview: Update azure-typespec/http-client-csharp version to prerelease {version}". If there is any library regeneration that fails in the script, or an error is encountered, the title should be suffixed with "Failed". The "Do Not Merge" label should be added and the PR should be opened as a draft PR.

In addition, the resulting regen-report.json file should be saved in the artifacts folder to allow ADO to upload the artifact for debugging purposes.

We should create the a new regen-preview.yaml file in https://github.com/microsoft/typespec/tree/main/packages/http-client-csharp/eng/pipeline.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add Regen Preview Pipeline #8847

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[jorgerangel-msft]

@copilot why do we need this? The regen preview script should already be handling updating the deps for us.

[jorgerangel-msft]

@copilot why is this needed? We are already pulling down the repo. This doesn't seem required for the existing publish pipeline and script?

[Copilot]

You're correct. The git config commands are not needed since the pipeline already handles repository initialization with git init and git checkout. Removed the unnecessary git config lines to match the pattern in Submit-AzureSdkForNetPr.ps1. (1668a32)