[alexjuv]

Summary

The migrate-dotnet9-to-dotnet10 skill did not say which Visual Studio version is needed to target .NET 10, and the field keyword diagnostic versions (VS 17.12+ / 17.14+) could be mistaken for the overall requirement. This PR documents the IDE requirement and clarifies the difference.

• IDE compatibility: Documents that targeting net10.0 with official support needs Visual Studio 2026 (18.0+). Visual Studio 17.14 can load SDK 10.0.100 but supports targeting only through net9.0. Links the official Microsoft compatibility table and release notes, and describes the CLI build option with a pinned SDK (global.json).
• SLNX: Notes that Microsoft's SLNX guidance does not specify minimum IDE versions, and keeps the dotnet new sln --format sln fallback.
• field diagnostics: States that the VS 17.12+ / 17.14+ versions describe when the diagnostics appear, not the .NET 10 requirement, and cross-references the new section.
• SKILL.md: Adds an IDE check to Step 1 and a Visual Studio compatibility bullet to Step 5. No other lines are changed.

Files changed: SKILL.md, references/sdk-msbuild-dotnet9to10.md, references/csharp-compiler-dotnet9to10.md (all under plugins/dotnet-upgrade/skills/migrate-dotnet9-to-dotnet10/).

Related issue

Fixes #1356

Validation

• npx --yes markdownlint-cli2 on the three modified Markdown files: passed.
• skill-validator check for dotnet-upgrade: passed; reference scan reported 0 errors.
• No new external domains: the added links are under learn.microsoft.com, which is already covered by microsoft.com in eng/known-domains.txt.
• No eval files changed, so the eval quality gate and evaluation run are not applicable.

Checklist

• I searched existing issues and pull requests to avoid duplicates.
• I kept this pull request focused and avoided unrelated refactors.
• I added or updated tests, evals, or documentation when changing skill or agent behavior.
• I updated CODEOWNERS when adding or moving owned content. (N/A: no content added or moved)
• I updated all marketplace manifests when plugin metadata changed. (N/A: no plugin metadata changed)
• I updated eng/known-domains.txt for any new external domains referenced by skill content. (N/A: no new domains)

Evaluation changes only

For every eval-related change, including a new eval:

• Scenarios are necessary, distinct, and use natural prompts.
• Graders cover the full result, accept the golden result, and reject a realistic mutation.
• No-op, dormancy, and statistical power are covered where needed.
• I ran the applicable production evaluation path and recorded the result above.
• If this fixes a failed eval, I classified the failure before editing skill content.
• If this broadly changes routing or behavior, I checked separate model-family evidence.

[Copilot]

🟢 Approval recommended

The focused documentation changes consistently address the compatibility gap, with no unresolved blocking issues identified.

No open issues 🎉

What changed in this PR

This PR addresses #1356 by clarifying Visual Studio requirements in the .NET 9-to-10 migration skill and distinguishing them from compiler diagnostic version labels.

Changes:

• Adds IDE compatibility checks to the initial assessment and CI/developer tooling guidance.
• Documents Visual Studio 2026 (18.0+) support, the CLI alternative, and the classic solution-format fallback.
• Clarifies that the field diagnostic versions do not indicate .NET 10 IDE support.

File	Description
plugins/​dotnet-upgrade/​skills/​migrate-dotnet9-to-dotnet10/​SKILL.md	Adds Visual Studio compatibility checks to migration steps.
plugins/​dotnet-upgrade/​skills/​migrate-dotnet9-to-dotnet10/​references/​sdk-msbuild-dotnet9to10.md	Documents IDE requirements, official sources, and CLI/solution-format alternatives.
plugins/​dotnet-upgrade/​skills/​migrate-dotnet9-to-dotnet10/​references/​csharp-compiler-dotnet9to10.md	Distinguishes diagnostic versions from IDE requirements and links compatibility guidance.

_{Review effort: Balanced}

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[Copilot]

🟡 Changes recommended

The new IDE compatibility check lacks a regression test for VS 17.14 with SDK 10.0.100, including the distinction between upgrading Visual Studio and using the CLI.

1 open issue

• Add IDE compatibility regression test for VS 17.14 and SDK 10.0.100 · New

_{Review effort: Balanced}