"Ctrl + Space" produces "a" character when used on some prompts in PowerShell terminal

[jtomkiew-mng]

Type: Bug

In PowerShell terminal using Ctrl + Space on certain prompts produces an "a" character when other system PowerShell terminals (native 5.1, native 7.4 or Windows Terminal) produce no output or a space.

Steps to reproduce

1. Open PowerShell 7 (pwsh) terminal
2. Type i
3. Press Ctrl + Space keys -> after a short discovery, this will show Display all xxx possibilities? (y or n) prompt, this is good so far

   If you are not prompted in this setup, type * instead of i in step 2.

4. Press Ctrl + Space keys again -> character a is inserted for unknown reason ☹️

Alternative steps to reproduce

1. Open PowerShell 7 (pwsh) terminal
2. Type Get-Credential, press Enter -> you will be prompted to username, this is good so far
3. Use Ctrl + Space shortcut -> character a is inserted for unknown reason ☹️

   Note: native terminal in this case inserts a space character, ignoring the Ctrl modifier.

$PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.4.11
PSEdition                      Core
GitCommitId                    7.4.11
OS                             Microsoft Windows 10.0.26200
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

$Host

Name             : ConsoleHost
Version          : 7.4.11
InstanceId       : 0eb31dd4-a06f-4ff5-ae95-b0d40a8c4b95
UI               : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture   : en-GB
CurrentUICulture : en-US
PrivateData      : Microsoft.PowerShell.ConsoleHost+ConsoleColorProxy
DebuggerEnabled  : True
IsRunspacePushed : False
Runspace         : System.Management.Automation.Runspaces.LocalRunspace

VS Code version: Code 1.105.0 (03c265b, 2025-10-08T14:09:35.891Z)
OS version: Windows_NT x64 10.0.26200
Modes:

System Info

Item	Value
CPUs	12th Gen Intel(R) Core(TM) i5-1240P (16 x 2112)
GPU Status	2d_canvas: enabled direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off trees_in_viz: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	31.70GB (12.28GB free)
Process Argv	--crash-reporter-id 5499e44f-8549-4bef-83c1-b92de90273d2
Screen Reader	no
VM	0%

Extensions: none

A/B Experiments

vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
usemplatestapi:31297334
aj953862:31281341
4f60g487:31327383
nes-set-on:31351930
6abeh943:31336334
ovs_pri_t:31398872
0cj2b977:31352657
gendocstringt:31395207
0574c672:31362109
cloudbuttont:31379625
todos-1:31390405
qwen_all_req:31398802
treatment_gpt5applypatchexclusively:31398171
3efgi100_wstrepl:31382709
trigger-command-fix:31379601
auto_model_enabled:31385282
use-responses-api:31390855
applesignin:31399435
dcggh915:31400023
6j29d282:31401256

[meganrogge]

can you create an issue for the powershell extension?

[jtomkiew-mng]

@meganrogge

Is PowerShell Extension repository handling all PowerShell related issue? If so, OK, I'll do that.

If not, then I'm confused, as this is not using the extension at all.

[meganrogge]

Just reading your issue description, sounds like this is related to the Powershell Extension

In PowerShell Extension terminal using Ctrl + Space on certain prompts produces an "a" character when other system

[jtomkiew-mng]

Just reading your issue description, sounds like this is related to the Powershell Extension

In PowerShell Extension terminal using Ctrl + Space on certain prompts produces an "a" character when other system

My bad, at first I was preparing an issue for Powershell Extension, but then I checked that this happens in regular terminal. I copied the first sentence without double checking.

Fixed the description, thanks.

If that was all, can you reopen?

[meganrogge]

Can you reproduce this in a terminal outside of VS Code?

[jtomkiew-mng]

Can you reproduce this in a terminal outside of VS Code?

No, here is a GIF from VSCode terminal:

And here is a GIF from pwsh.exe (7.4) terminal:

> The same on Windows PowerShell and Windows Terminal.

[Tyriar]

ctrl+space isn't natively supported in ptys (unless we implement xtermjs/xterm.js#5424 and it's supported by conpty/pwsh). We implement it by sending a special "key" via a VS Code keybinding:

vscode/src/vs/workbench/contrib/terminalContrib/sendSequence/browser/terminal.sendSequence.contribution.ts

Lines 133 to 140 in b808eda

	// Map certain keybindings in pwsh to unused keys which get handled by PSReadLine handlers in the
	// shell integration script. This allows keystrokes that cannot be sent via VT sequences to work.
	// See https://github.com/microsoft/terminal/issues/879#issuecomment-497775007
	registerSendSequenceKeybinding('\x1b[24~a', { // F12,a -> ctrl+space (MenuComplete)
	when: ContextKeyExpr.and(TerminalContextKeys.focus, ContextKeyExpr.equals(TerminalContextKeyStrings.ShellType, GeneralShellType.PowerShell), TerminalContextKeys.terminalShellIntegrationEnabled, CONTEXT_ACCESSIBILITY_MODE_ENABLED.negate()),
	primary: KeyMod.CtrlCmd | KeyCode.Space,
	mac: { primary: KeyMod.WinCtrl | KeyCode.Space }
	});

Then handle it in shell integration:

vscode/src/vs/workbench/contrib/terminal/common/scripts/shellIntegration.ps1

Line 254 in b808eda

Set-MappedKeyHandler -Chord Ctrl+Spacebar -Sequence 'F12,a'

The reason it's failing is because this is only handled in PSReadLine and you're running Get-Credential. This is out of scope for now, perhaps one day we'll implement win32-input-mode (unlikely) or kitty keyboard protocol (likely, but needs other things to support it).