Made -w 0 target the window of the calling terminal. - #20733

wt -w 0 now runs the commandline in the window that wt was run from, instead of the most recently used window. The calling terminal session is identified by WT_SESSION in the caller's environment, as proposed in the Session Management spec. If wt wasn't run from a Terminal session (for example from Explorer or the Run dialog), or the session no longer exists, it falls back to the most recently used window as before.

References

• Closes spawn new tab in quake window with wt -w 0 #10561, which Mike Griese (@zadjii-msft) repurposed to "Actually use the current window for wt -w 0".
• Spec: #4472 - Windows Terminal Session Management, "Running commands in the current window"
• Related: [defterm] Terminal always brings itself to the foreground, even when the client app was launched in the background #20692

Details

• WindowEmperor::_dispatchCommandline first looks for the window hosting the caller's session, then falls back to the existing logic (_dispatchCommandlineCurrentDesktop / _mostRecentWindow).
• The environment block forwarded by wt.exe is parsed with til::env. TerminalPage::HostsSession walks the panes of all tabs and compares its connection's SessionId(). The lookup happens at dispatch time, follows panes that were moved to another window.
• This applies to WindowingMode::UseExisting (-w 0, -w last, and "windowingBehavior": "useExisting") and to UseAnyExisting. In both cases the calling window is what "an existing window" should mean.
• A spoofed WT_SESSION can only target an existing window, which -w <id> already allows.
• Built from main with VS 2022 17.14 (v143) and SDK 10.0.26100.9169.