feat(shell): self-report shell identity via OSC 9001;ShellType

[vanzue]

What

Lets shells self-report their identity each prompt via the private OSC 9001;ShellType;<name>;<version> sub-action, so the terminal always knows which shell owns a pane — even after a nested shell (pwsh -> wsl -> exit) returns, where there's no reliable "I exited" signal.

Why

Autofix was recommending PowerShell commands (e.g. Get-ChildItem) inside a WSL/bash pane. The autofix shell context derived shell from the pane's pid -> process image name, which inside a wsl.exe / pwsh.exe host can't see the real foreground shell drawing the prompt. The prompt is the natural "who's in charge now" signal, so the shell reports it on every prompt.

How

• Emit: PowerShellShellIntegration.h reports pwsh / powershell + version; BashShellIntegration.h reports bash or wsl:<distro> + version (WSL reuses BashFlavor, so one edit covers Git Bash + every distro).
• Plumb: replicates the WorkingDirectory data flow end to end — adaptDispatch DoWTAction -> ITerminalApi::SetShellType -> Terminal -> ControlCore -> ICoreState -> TermControl -> PaneInfo -> COM _toJson (shell / shell_version). wtcli list-panes / get-active-pane now expose the live shell per pane.
• Consume: shell_from_active (autofix) now prefers the OSC-reported shell over the pid lookup; pid stays as the fallback for panes without shell integration.
• Deploy: bumps the shell-integration script kVersion (1 -> 2) so existing users actually receive the new ShellType line — the install orchestrator only rewrites the managed block when the versioned script filename changes.
• Cleanup: removes the dead OSC 9001 WtaReq / WtaRes in-band handler (superseded by the out-of-band COM IProtocolServer channel).

Test

• UnitTests_TerminalCore TerminalApiTest::SetShellType — feeds the OSC, asserts GetShellName() / GetShellVersion() (name+version, name-only, empty, last-writer-wins, no interference with CmdNotFound).
• ShellIntegrationTests *_UpgradesWhenBlockReferencesOlderScriptVersion — the kVersion bump reaches existing users (block referencing an older script version is rewritten; new script contains 9001).
• Rust shell_from_active_prefers_osc_reported_shell + existing shell_from_active_resolves_pid — OSC field wins over pid; empty/whitespace falls back.
• WSL end-to-end integration tests (Feature.AutofixPane.Tests.ps1, gated on a runnable WSL distro + the dev package): WSL pane self-reports wsl:<distro> through the protocol, and autofix suggests bash (not PowerShell) syntax.
• Full bcz no_clean build: 0 errors. Manually verified on the dev package: a WSL pane reports wsl:<distro> and autofix suggests bash-syntax fixes.

---

Closes #352 (context awareness: agent pane & autofix recognize the active WSL/bash shell). Part of #200.

[Copilot]

Pull request overview

This PR adds a new shell-integration signal (OSC 9001;ShellType;<name>;<version>) that lets the foreground shell report its identity on every prompt, and propagates that information through the Terminal core, control/app layers, and the Terminal Protocol COM JSON so WTA/autofix can reliably choose shell-appropriate fixes (especially across nested shells like pwsh → wsl → exit).

Changes:

• Adds ShellType handling in the VT action dispatcher and a new ITerminalApi::SetShellType plumbing path to store shell name/version in Terminal and expose it through ControlCore/TermControl into protocol PaneInfo and COM JSON (shell, shell_version).
• Updates PowerShell and bash/WSL shell integration snippets to emit OSC 9001;ShellType each prompt.
• Updates WTA’s pane JSON parsing to prefer the OSC-reported shell field (with tests) and fall back to pid-based resolution when absent/empty.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tools/wta/src/protocol/acp/client.rs	Prefer OSC-reported shell in active-pane JSON; adds unit test for precedence/fallback behavior.
src/terminal/adapter/ut_adapter/adapterTest.cpp	Updates test mock ITerminalApi implementation with SetShellType.
src/terminal/adapter/ITerminalApi.hpp	Adds SetShellType(shellName, shellVersion) to the terminal API contract.
src/terminal/adapter/adaptDispatch.cpp	Implements OSC 9001;ShellType WT action parsing and forwards to ITerminalApi.
src/host/outputStream.hpp	Adds SetShellType to conhost internal API surface (no-op implementation).
src/host/outputStream.cpp	No-op SetShellType for conhost, documenting feature is WT-only.
src/cascadia/WindowsTerminal/TerminalProtocolComServer.cpp	Serializes pane shell and shell_version into protocol JSON.
src/cascadia/UnitTests_TerminalCore/TerminalApiTest.cpp	Adds TerminalCore unit test validating ShellType parsing/state behavior.
src/cascadia/TerminalProtocol/TerminalProtocol.idl	Extends PaneInfo with Shell and ShellVersion.
src/cascadia/TerminalCore/TerminalApi.cpp	Implements Terminal::SetShellType and one-time telemetry event.
src/cascadia/TerminalCore/Terminal.hpp	Stores shell name/version and adds getters + ITerminalApi override.
src/cascadia/TerminalCore/Terminal.cpp	Implements GetShellName() / GetShellVersion() accessors.
src/cascadia/TerminalControl/TermControl.h	Adds ShellName() / ShellVersion() accessors to TermControl.
src/cascadia/TerminalControl/TermControl.cpp	Wires TermControl shell accessors through to ControlCore.
src/cascadia/TerminalControl/ICoreState.idl	Adds ShellName / ShellVersion properties to core state interface.
src/cascadia/TerminalControl/ControlCore.h	Adds ShellName() / ShellVersion() accessors to ControlCore.
src/cascadia/TerminalControl/ControlCore.cpp	Reads shell name/version under terminal read lock for the control layer.
src/cascadia/TerminalApp/TerminalPage.Protocol.cpp	Plumbs shell name/version into PaneInfo returned by protocol APIs.
src/cascadia/inc/PowerShellShellIntegration.h	Emits OSC 9001;ShellType each PowerShell prompt with edition + version.
src/cascadia/inc/BashShellIntegration.h	Emits OSC 9001;ShellType each bash prompt; reports wsl:<distro> under WSL.

[Copilot]

Pull request overview

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

[github-actions]

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Backgrounder CANTCALLOUT Ccc cplusplus ctl Debian dotnet drv endptr EOFs evt Fullwidth gitlab hdr idl IME inbox ININPUTSYNCCALL intelligentterminal Ioctl KVM lbl lld lsb NODEFAULT NONINFRINGEMENT notif oss outdir Podcast pri prioritization rcv segfault SND sourced SWP Tbl testname transitioning unk unparseable unregisters Virt VMs webpage websites WINVER xsi

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... in a clone of the git@github.com:microsoft/intelligent-terminal.git repository
on the dev/vanzue/what-is-shell branch (ℹ️ how do I use this?):

curl -s -S -L 'https://raw.githubusercontent.com/check-spelling/check-spelling/cfb6f7e75bbfc89c71eaa30366d0c166f1bd9c8c/apply.pl' |
perl - 'https://github.com/microsoft/intelligent-terminal/actions/runs/28037796049/attempts/1' &&
git commit -m 'Update check-spelling metadata'

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Dictionary	Entries	Covers	Uniquely
cspell:csharp/csharp.txt	32	2	2
cspell:aws/aws.txt	232	2	2
cspell:fonts/fonts.txt	536	1	1

Consider adding to the extra_dictionaries array (in the .github/actions/spelling/config.json file):

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[Copilot]

Pull request overview

Copilot reviewed 37 out of 37 changed files in this pull request and generated 1 comment.