Add wslc system info command

[beena352]

Summary of the Pull Request

Adds wslc system info (and wslc info as a root alias) that shows client version details and session manager state in both table and JSON formats. The command does not start a VM, it queries the session manager service the same way session list does.

PR Checklist

• Closes: Link to issue wslc: support wslc system info #41282
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

What it shows:

• Client block: the same version info as wsl --version (package version, kernel, wslg, msrdc, direct3d, dxcore, Windows version), plus the settings file path. Dev builds also show the compiler version, commit hash, and build time.
• Server block: session manager version and the list of active sessions (reuses the same table as session list).
  Design choices:
• No VM boot. The command only calls IWSLCSessionManager::GetVersion and ListSessions, which don't take a lease. This is the same pattern as session list
• --format json builds the full document before writing, so a service failure fails the whole command. Table mode streams the client block first, then flushes stdout before querying the service- a stopped service still shows the client info
• The session table is hidden when there are no sessions (no empty header row). session list keeps showing the header - that's intentional, they serve different purposes
• Terminal::Flush was added to handle a CRT buffering issue: when stdout is redirected it's fully buffered, but stderr is not, so a later error can appear before earlier output in the same file. The flush after the client block prevents that
• The WriteSessionTable helper is shared between ListSessions and ShowSystemInfo in SessionTasks.cpp, which is why there's no separate SystemTasks file
• JSON session entries use "ID" (not "Id") to match the convention in ContainerTasks and NetworkTasks.

What this doesn't do:

• No Docker engine version or container runtime info. That would need a running VM and HTTP client plumbing-separate work
• --session is a global argument and is silently accepted. This matches how other non-session commands behave.

Validation Steps Performed

• Ran wslc system info and wslc info with 0 and 1 active sessions - output is correct in both cases
• Ran wslc system info --format json and verified valid JSON with Client and Server sections, correct key casing ("ID", not "Id")
• Ran wslc system info --format invalid - clean error message, exit code 1, nothing on stdout
• CLI parse tests: 12 new cases for system info and info with valid/invalid args
• Structural unit tests: 5 new tests covering command name, subcommands, format argument, and registration under both system and root
• E2E tests: 5 new tests (table output, invalid format, JSON validation with key assertions, root alias equivalence, does-not-create-session check)
• Terminal unit test: 1 new test for Flush - verified it goes red when Flush is stubbed out, green with the real implementation

[Copilot]

Pull request overview

Adds wslc system info and the top-level wslc info alias, providing client, server, and session details in table or JSON formats.

Changes:

• Added system information command and session-manager version retrieval.
• Added localized output and terminal flushing.
• Added parser, unit, and end-to-end test coverage.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/windows/wslc/WSLCCLITerminalUnitTests.cpp	Tests terminal output flushing.
test/windows/wslc/WSLCCLICommandUnitTests.cpp	Tests command structure and registration.
test/windows/wslc/e2e/WSLCE2EGlobalTests.cpp	Tests table, JSON, alias, and session behavior.
test/windows/wslc/CommandLineTestCases.h	Adds command-line parser cases.
src/windows/wslc/tasks/SessionTasks.h	Declares system information task support.
src/windows/wslc/tasks/SessionTasks.cpp	Implements system information output.
src/windows/wslc/services/SessionService.h	Declares session-manager version retrieval.
src/windows/wslc/services/SessionService.cpp	Retrieves the session-manager version.
src/windows/wslc/core/Terminal.h	Declares terminal output flushing.
src/windows/wslc/core/Terminal.cpp	Implements terminal output flushing.
src/windows/wslc/commands/SystemCommand.h	Defines the system information command interface.
src/windows/wslc/commands/SystemCommand.cpp	Implements the system information command.
src/windows/wslc/commands/RootCommand.cpp	Registers the top-level info alias.
localization/strings/en-US/Resources.resw	Adds localized system information strings.

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[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

Suppressed comments (2)

src/windows/wslc/tasks/SessionTasks.cpp:177

• The new sessions.empty() branch changes the table contract by suppressing the session-table header, but the E2E additions do not assert this zero-session case: the table test only checks section/version strings and the session state is environment-dependent. Add a deterministic zero-session test that verifies Sessions: 0 is present while the session-table ID header is absent.

        if (!sessions.empty())
        {
            WriteSessionTable(context.Terminal, sessions);
        }

test/windows/wslc/WSLCCLICommandUnitTests.cpp:261

• This unit test searches only by Name(), so it also passes if the root-level registration is removed because system already contains an info child. That means it does not pin the second registration as the comment claims; also check the command's FullName() (for example, root:info) or count the registrations.

            if (subcmd->Name() == SystemInfoCommand::CommandName)

[Blue (OneBlue)]

We shouldn't display wslg and msrdc versions, since they're irrelevant to wslc

[Blue (OneBlue)]

(Same for the below bloc)