Repository navigation
[Windows] Every shell command spawns a visible PowerShell console window (new console, not hidden) that stays open for the command's lifetime #4549
Description
Summary
On Windows, Copilot CLI briefly flashes an empty PowerShell / conhost console
window every time the agent executes a shell command. During normal agent
activity (many commands per task) this produces near-constant window flashing
that momentarily steals focus and is very distracting.
This appears to be the same class of bug as the already-fixed git / hook /
path-resolution flashes (PRs #10235 and #11037) and the open MCP-startup flash
(#3171), but on the general agent shell-command execution path, which is
still affected.
Environment
- Copilot CLI: 1.0.80 (latest at time of report)
- OS: Windows 11 24H2, build 26100.9106
(registryProductNamecosmetically reads "Windows 10 Enterprise" on this build) - Shell: PowerShell (default on Windows)
- Terminal: Windows Terminal
Steps to reproduce
- Launch
copilotin Windows Terminal on Windows 11. - Ask the agent to run essentially any shell command (e.g. a simple
Get-ChildItem, or anynode -e "..."invocation). - Watch the screen while the command executes.
Expected
Shell commands run without any visible console window appearing — as already
happens for git commands and for hook / path-resolution after #10235 / #11037.
Actual
A blank PowerShell / conhost window flashes on screen for each spawned
command, briefly stealing focus.
Real-world example that triggers it
This is an actual command a session spawned (a mermaid-diagram validation step).
Every command shaped like this flashes a window:
$node = "C:\ProgramData\global-npm\node_modules\node\bin\node.exe"
$script = @'
const fs = require("fs");
const files = process.argv.slice(2);
let idx = 0;
for (const f of files) {
const txt = fs.readFileSync(f, "utf8").split(/\r?\n/);
let inBlock = false, buf = [], start = 0;
for (let i = 0; i < txt.length; i++) {
const line = txt[i];
if (!inBlock && /^\s*```mermaid\s*$/.test(line)) { inBlock = true; buf = []; start = i + 1; continue; }
if (inBlock && /^\s*```\s*$/.test(line)) {
inBlock = false; idx++;
const base = f.replace(/^.*[\\/]/, "");
const out = `${process.env.TEMP}\\mmvalidate\\block_${idx}_${base}_L${start+1}.mmd`;
fs.writeFileSync(out, buf.join("\n"));
continue;
}
if (inBlock) buf.push(line);
}
}
'@
Set-Content -Path "$env:TEMP\mmvalidate\extract.js" -Value $script -Encoding utf8
& $node "$env:TEMP\mmvalidate\extract.js" "$env:TEMP\brga.md" "$env:TEMP\rad.md" "$env:TEMP\rrd.md"Note: the window that flashes is the outer powershell.exe host the CLI
spawns to run the command — not node.exe. node is a console app and
inherits the parent console, so it does not create a window on its own. The
content of the command is irrelevant; any shell command triggers the flash.
Likely root cause
The CLI runs shell commands on Windows via node-pty / ConPTY (conpty.node).
The pseudo-console host (conhost.exe) for the spawned command is not being
suppressed on this path, so its window briefly appears. The earlier fixes added
window suppression (windowsHide / CREATE_NO_WINDOW) only to specific paths:
- #10235 — "Git commands no longer flash a console window on Windows"
- #11037 — "Prevent brief console windows from flashing on Windows when the
agent runs hook commands or resolves command paths"
The main agent command-execution path appears not to have the equivalent
suppression.
Related
- [Windows] CMD windows flash on screen when MCP servers start #3171 — [Windows] CMD windows flash on screen when MCP servers start
(same class of bug, different trigger)
Suggested fix
Apply the same window-suppression used in #10235 / #11037 to the agent's
shell-command execution path — i.e. ensure the ConPTY / child-process spawn
passes windowsHide: true (or creates the console host without a visible
window / uses a headless OpenConsole host consistently) for every command the
agent runs, not just git, hooks, and path resolution.
Activity
[-][Windows] A PowerShell/conhost window flashes on screen for every shell command the agent runs[/-][+][Windows] Every shell command spawns a visible PowerShell console window (new console, not hidden) that stays open for the command's lifetime[/+]siramk2022 commentedon Aug 21, 2026
Correction + hard evidence — updating the "brief flash" framing in the description above.
After reproducing on the affected machine, the symptom is more specific (and more severe) than a brief flash: each shell command is spawned in a brand‑new, visible console window that stays open for the entire lifetime of that command's process. Short commands flash; anything longer‑running (node scripts, watchers, mermaid/validation steps, anything that waits) leaves a PowerShell window sitting on screen. Because the CLI runs many commands per task, visible windows accumulate.
Process‑tree proof (Windows 11 24H2, build 26100.9106, CLI 1.0.80)
Launcher chain and per‑command console:
A child process that inherits its parent's console never gets its own
conhost.exe; theconhostbelongs to whoever allocated the console. A dedicatedconhostperpwshtherefore proves a new console is being created for every command — i.e. the shell is spawned withoutwindowsHide: true(console‑less parent /CREATE_NEW_CONSOLE‑style behavior), not into a hidden or inherited console.Two consecutive commands, each allocated a fresh console:
Invocation the CLI uses for each command:
It is NOT a process leak
A system‑wide scan for orphaned
pwsh/powershell/conhost(parent process gone) found only 1 orphanedconhost, from an unrelated app. So the windows are not leaked zombies — each one is a live, visible console for a currently‑running command, and it stays on screen until that command'spwshexits. The fix is to spawn the shell hidden, not to reap leaks.Root cause (refined)
The shell child is created with a new console and without
windowsHide: true, so Windows displays the console window and keeps it visible until the command'spwshprocess exits. This is the same class of defect fixed for other paths but on the main agent command‑execution path:Suggested fix (refined)
Pass
windowsHide: trueon the shell‑command spawn (and/or avoidCREATE_NEW_CONSOLE/detachedfor foreground commands, or attach a headless ConPTY host) so the per‑commandpwshruns without a visible console. Extend the suppression already applied in #10235 / #11037 to cover every command the agent runs.exetico commentedon Sep 14, 2026
On my machine, it even keeps the windows open, resulting in 20-50 PowerShell windows runnning in "Terminal", which I'd need to close manually. I've not faced this issue before.