Fix --apphost directory resolution for commands

[adamint]

Description

Fix --apphost resolution for stop-side CLI commands.

Fixes #16360

This change:

• keeps explicit AppHost project-file paths on the direct socket lookup path so commands can still attach to an already-running AppHost
• continues to resolve directory-valued --apphost inputs via IProjectLocator, with explicit directory-specific diagnostics for zero or multiple AppHosts
• adds resolver unit tests and updates the non-interactive stop E2E scenario to cover directory-based --apphost

Reviewer testing steps using the built CLI:

1. ./localhive.sh
2. ~/.aspire/bin/aspire --version
3. ~/.aspire/bin/aspire new aspire-starter --name ReviewApp --output /tmp/ReviewApp --non-interactive
4. In one terminal: cd /tmp/ReviewApp/ReviewApp.AppHost && dotnet run
5. In a second terminal from above the solution root: cd /tmp && ~/.aspire/bin/aspire stop --non-interactive --apphost ReviewApp

Expected result: the running AppHost is found and stopped via the solution directory path.

Validation performed:

• ./dotnet.sh test --project tests/Aspire.Cli.Tests/Aspire.Cli.Tests.csproj --no-launch-profile -- --filter-not-trait "quarantined=true" --filter-not-trait "outerloop=true"

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire.dev issue:
      • New issue
  • No

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 16406

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 16406"

[Copilot]

Pull request overview

Aligns stop-side CLI commands with start behavior by normalizing explicit --apphost inputs (including directory paths) through IProjectLocator.UseOrFindAppHostProjectFileAsync(...) before attempting backchannel socket resolution, fixing #16360.

Changes:

• Updates AppHostConnectionResolver to resolve explicit --apphost via IProjectLocator, and to surface project-resolution failures distinctly from “no running AppHost found”.
• Plumbs IProjectLocator into commands that use AppHostConnectionResolver and adjusts exit-code handling to preserve existing UX.
• Adds a localized interaction string for unsupported AppHosts and adds/updates unit + E2E coverage for directory-valued --apphost.

Reviewed changes

Copilot reviewed 31 out of 32 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/Aspire.Cli.Tests/Commands/StopCommandTests.cs	Adds unit coverage for explicit --apphost project-resolution failure vs. successful resolution path.
tests/Aspire.Cli.EndToEnd.Tests/StopNonInteractiveTests.cs	Updates stop non-interactive E2E scenario to exercise directory-valued --apphost.
src/Aspire.Cli/Backchannel/AppHostConnectionResolver.cs	Resolves explicit --apphost through IProjectLocator and returns structured project-resolution errors (exit code + message).
src/Aspire.Cli/Projects/ProjectLocator.cs	Adds ProjectLocatorErrorHelper to centralize mapping from ProjectLocatorFailureReason to exit code + localized message.
src/Aspire.Cli/Commands/BaseCommand.cs	Switches to shared ProjectLocatorErrorHelper mapping for consistent error messages/exit codes.
src/Aspire.Cli/Commands/StopCommand.cs	Uses updated resolver and preserves “no running AppHost” UX while returning distinct exit codes for resolution failures.
src/Aspire.Cli/Commands/WaitCommand.cs	Plumbs IProjectLocator into resolver and returns project-resolution exit codes when applicable.
src/Aspire.Cli/Commands/ResourceCommand.cs	Plumbs IProjectLocator into resolver and returns project-resolution exit codes when applicable.
src/Aspire.Cli/Commands/LogsCommand.cs	Plumbs IProjectLocator into resolver and returns project-resolution exit codes when applicable.
src/Aspire.Cli/Commands/DescribeCommand.cs	Plumbs IProjectLocator into resolver and returns project-resolution exit codes when applicable.
src/Aspire.Cli/Commands/ExportCommand.cs	Plumbs IProjectLocator into resolver (connection resolution now normalizes explicit --apphost).
src/Aspire.Cli/Commands/McpToolsCommand.cs	Plumbs IProjectLocator into resolver and preserves “no running AppHost” UX vs. resolution errors.
src/Aspire.Cli/Commands/McpCallCommand.cs	Plumbs IProjectLocator into resolver and returns project-resolution exit codes when applicable.
src/Aspire.Cli/Commands/TelemetryLogsCommand.cs	Plumbs IProjectLocator into resolver (telemetry commands now normalize explicit --apphost).
src/Aspire.Cli/Commands/TelemetrySpansCommand.cs	Plumbs IProjectLocator into resolver (telemetry commands now normalize explicit --apphost).
src/Aspire.Cli/Commands/TelemetryTracesCommand.cs	Plumbs IProjectLocator into resolver (telemetry commands now normalize explicit --apphost).
src/Aspire.Cli/Commands/TelemetryCommandHelpers.cs	Treats project-resolution failures as errors (propagates exit code) while keeping “no running AppHost” non-fatal behavior.
src/Aspire.Cli/Resources/InteractionServiceStrings.resx	Adds NoSupportedAppHostsFound localized resource.
src/Aspire.Cli/Resources/InteractionServiceStrings.Designer.cs	Regenerates strongly-typed accessor for NoSupportedAppHostsFound.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.cs.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.de.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.es.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.fr.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.it.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.ja.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.ko.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.pl.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.pt-BR.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.ru.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.tr.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.zh-Hans.xlf	Adds NoSupportedAppHostsFound trans-unit.
src/Aspire.Cli/Resources/xlf/InteractionServiceStrings.zh-Hant.xlf	Adds NoSupportedAppHostsFound trans-unit.

Files not reviewed (1)

• src/Aspire.Cli/Resources/InteractionServiceStrings.Designer.cs: Language not supported

[radical]

Looks good — clean extraction of the project-resolution logic into ProjectLocatorErrorHelper, consistent plumbing of IProjectLocator through all command constructors, and clear separation between "project not found" (hard error) and "AppHost not running" (informational) in the result model.

The new AppHostNotRunningAtPath message with relative paths is a nice UX improvement, and the test coverage (unit, integration, and E2E with directory resolution) is solid.

One non-blocking suggestion left inline about tightening the IsProjectResolutionError check.