update-library-template

name	update-library-template
description	Merges the latest Library.Template into this repo (at position of HEAD) and resolves conflicts.
disable-model-invocation	true

Instructions

1. Run ./tools/MergeFrom-Template.ps1 from the repo root.
2. Resolve merge conflicts, taking into account conflict resolution policy below.
3. Validate the changes, as described in the validation section below.
4. Committing your changes (if applicable).

Conflict resolution policy

There may be special notes that describe special considerations for certain files or scenarios to help you resolve conflicts appropriately. Always refer to that file before proceeding. In particular, focus on the incoming part of the file, since it represents the changes from the Library.Template that you are merging into your repo. Also refer to .github/prompts/repo-merge-notes.md for notes specific to this repo (e.g. which deleted files to keep, which customizations to preserve). Also consider that some repos choose to reject certain Library.Template patterns. For example the template uses MTPv2 for test projects, but a repo might have chosen not to adopt that. When resolving merge conflicts, consider whether it looks like the relevant code file is older than it should be given the changes the template is bringing in. Ask the user when in doubt as to whether the conflict should be resolved in favor of 'catching up' with the template or keeping the current changes.

Use #runSubagent to analyze and resolve merge conflicts across files in parallel.

Keep Current files

Conflicts in the following files should always be resolved by keeping the current version (i.e. discard incoming changes):

• README.md

Deleted files

Very typically, when the incoming change is to a file that was deleted locally, the correct resolution is to re-delete the file.

In some cases however, the deleted file may have incoming changes that should be applied to other files. The test/Library.Tests/Library.Tests.csproj file is very typical of this. Changes to this file should very typically be applied to any and all test projects in the repo. You are responsible for doing this in addition to re-deleting this template file.

Files deleted by the template

When the template deletes a file that exists locally, check the template's commit history to understand why it was removed. Use the GitHub commit history page for the file (e.g. https://github.com/aarnott/Library.Template/commits/microbuild/path/to/file) to find the relevant commit. If the template restructured or centralized the functionality (e.g. OptProf pipelines moved to a centralized VS pipeline), accept the deletion. If the file contains repo-specific customizations not present in the template, keep it.

Files deleted locally but updated by the template

These show as "deleted by us" conflicts. Refer to repo-merge-notes.md for this repo's specific decisions on which files to keep or re-delete.

Updating package and SDK versions

After the merge, always check global.json for MSBuild Sdks with names starting with Microsoft.VisualStudio.Internal.MicroBuild. These SDK versions should match the value of the MicroBuildVersion property found in Directory.Packages.props. Always take the latest of the versions you see among these SDKs and the MicroBuildVersion property.

Validation

Validate the merge result (after resolving any conflicts, if applicable). Use #runSubagent for each step.

1. Verify that dotnet restore succeeds. Fix any issues that come up.
2. Verify that dotnet build succeeds.
3. Verify that tests succeed by running tools/dotnet-test-cloud.ps1.

While these validations are described using dotnet CLI commands, some repos require using full msbuild.exe. You can detect this by checking the azure-pipelines/dotnet.yml or .github/workflows/build.yml files for use of one or the other tool.

You are not responsible for fixing issues that the merge did not cause. If validation fails for reasons that seem unrelated to the changes brought in by the merge, advise the user and ask how they'd like you to proceed. That said, sometimes merges will bring in SDK or dependency updates that can cause breaks in seemingly unrelated areas. In such cases, you should investigate and solve the issues as needed.

Committing your changes

If you have to make any changes for validations to pass, consider whether they qualify as a bad merge conflict resolution or more of a novel change that you're making to work with the Library.Template update. Merge conflict resolution fixes ideally get amended into the merge commit, while novel changes would go into a novel commit after the merge commit.

Always author your commits using git commit --author "🤖 Copilot <[e-mail]>" (and possibly other parameters). Describe the nature of the merge conflicts you encountered and how you resolved them in your commit message.

Later, if asked to review pull request validation breaks, always author a fresh commit with each fix that you push, unless the user directs you to do otherwise.