Use C# Dev Kit workspace dotnet for debugger checks

[JakeRadMSFT]

Summary

Fixes #9732 by making debugger prerequisite discovery consume C# Dev Kit's authoritative Workspace Requirements host when the installed Dev Kit supports the new optional contract.

• Extends C#'s local CSharpDevKitExports shape with optional getWorkspaceDotnetHost().
• Reuses the existing non-blocking Dev Kit activation callback; C# activation does not await Dev Kit activation.
• Defers only debugger prerequisite completion, with a bounded 90-second wait and handled rejection paths.
• Uses the exact selected executable and environment for dotnet --info, dotnet --list-runtimes, architecture selection, and debugger DOTNET_ROOT.
• Suppresses C#'s competing SDK notification when Workspace Requirements reports blocked.
• Preserves current ambient/configured discovery for absent, bypassed, old, failed, or not-applicable Dev Kit.

Compatibility matrix

C# Dev Kit state	Behavior
Absent	Existing standalone C# discovery and notification behavior
Bypassed with dotnet.preferCSharpExtension	Existing standalone C# behavior; Dev Kit is not activated for this decision
Old exports without getWorkspaceDotnetHost()	Existing standalone fallback; no minimum Dev Kit version
Activation rejects	Handled bounded fallback to standalone behavior
Activation does not settle within the bound	C# suppresses competing remediation rather than racing Workspace Requirements
New export reports blocked	No ambient probe and no duplicate C# SDK notification
New export reports ready	Exact returned executable/environment used for debugger prerequisite probes
New export reports not-applicable	Existing standalone fallback

Activation safety

C# continues to call Extension.activate() without synchronously awaiting it from the C# activation path. The resulting promise is passed only to debugger prerequisite completion. This allows C# activation to return, lets Dev Kit finish its existing C#→Dev Kit activation cycle, handles rejection/timeouts, and memoizes the decision per activation.

Validation

• TypeScript compile: passed (tsc --noEmit)
• ESLint on all changed files: passed
• OmniSharp unit suite: 39 suites passed; 410 tests passed; 1 skipped
• Focused compatibility tests: 9 passed
• Development package build: passed
• Combined real VS Code UI session with no ambient dotnet on PATH: Workspace Requirements opened in blocked state and the notification center did not contain The .NET SDK cannot be located

Follow-up producer change

The corresponding optional C# Dev Kit export is implemented in https://devdiv.visualstudio.com/DevDiv/_git/vs-green/pullrequest/778204 so this C# change remains safe to ship first. Until that producer version is installed, feature detection follows the old-export fallback row above.

[JakeRadMSFT]

/azp run

[azure-pipelines]

Commenter does not have sufficient privileges for PR 9733 in repo dotnet/vscode-csharp

[Copilot]

🔵 Needs a closer look

It changes debugger prerequisite discovery and activation-time behavior (including timeouts and environment shaping) across multiple entry points and warrants final human validation across platforms and Dev Kit states.

Pull request overview

This PR updates the C# extension’s debugger prerequisite discovery to optionally consume C# Dev Kit’s authoritative “Workspace Requirements” selected dotnet host (when available), ensuring the debugger uses the exact executable/environment selected for the workspace and avoiding duplicate/competing SDK remediation messaging.

Changes:

• Extend CSharpDevKitExports with an optional getWorkspaceDotnetHost() contract and add a resolver with bounded waiting/fallback behavior.
• Plumb the resolved workspace dotnet host through CoreCLR debugger activation/install checks and debug adapter launch configuration (including DOTNET_ROOT).
• Add unit coverage for workspace-host resolution behavior and for passing a selected dotnet + environment into dotnet --info / --list-runtimes.

File summaries

File	Description
test/omnisharp/omnisharpUnitTests/coreclrDebug/workspaceDotnetHost.test.ts	Adds unit tests validating bounded Dev Kit export resolution and fallback/blocked behaviors.
test/omnisharp/omnisharpUnitTests/coreclrDebug/getDotnetInfo.test.ts	Adds unit test validating exact executable/env propagation for dotnet --info / --list-runtimes.
src/shared/utils/getDotnetInfo.ts	Adds optional overrides for dotnet executable path and environment, and applies them consistently across probes.
src/main.ts	Threads the Dev Kit exports promise through to the CoreCLR debugger activation path.
src/csharpDevKitExports.ts	Defines WorkspaceDotnetHost and adds optional getWorkspaceDotnetHost() export.
src/coreclrDebug/workspaceDotnetHost.ts	New resolver that waits (bounded) for Dev Kit activation/host selection and maps it to C#’s needs.
src/coreclrDebug/util.ts	Extends .NET CLI check to accept an explicit dotnet executable and environment.
src/coreclrDebug/activate.ts	Uses resolved workspace host for debugger install prerequisites and debug adapter execution environment decisions.
src/activateRoslyn.ts	Returns Dev Kit exports as a promise so downstream components can defer specific work without awaiting activation.

Review details

• Files reviewed: 9/9 changed files
• Comments generated: 0
• Review effort level: Lite

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