Sessions

Session persistence is the reason WinMux exists. Everything else loses to it when they conflict.

What is saved

The layout tree, every window’s position, which tabs exist and which is active, and for each pane: its kind, title, the program and arguments it was started with, any environment overrides, and its working directory.

Saving happens continuously — on a debounce after any layout change, and on a timer — so a crash costs you nothing. The status bar shows the session file and how long ago it saved.

What is not

Process state. A restored shell is a new shell started in the right directory. Scrollback, running jobs, and whatever a full-screen program had on screen are gone, because nothing can bring them back. WinMux says so when it restores rather than letting you find out.

The working directory

This is the genuinely hard part, and Windows Terminal has an open issue on it too. WinMux tries three things and keeps the best answer, recording which method produced it so a stale one is not trusted over a fresh one.

Method	Works when	Measured
The shell reports it (OSC 9;9 / OSC 7)	you install the profile snippet	the only method that works for PowerShell and WSL
Reading the deepest child process	a nested program is running	covers the case a stale shell report misses
Reading the pane’s own process	for cmd	permanently stale for PowerShell, meaningless for WSL

Install the snippets

They are not a power-user extra. PowerShell’s process working directory never changes when you cd — Set-Location updates the provider location, not the process — so without the snippet a PowerShell pane restores to the wrong directory the moment you move, and that is the headline feature failing silently.

Settings → Working directories → Set up… installs them, for PowerShell, pwsh, cmd and bash.

The status bar’s left segment shows the focused pane’s captured directory and how it was captured, so you can see the difference between “shell-reported” and “where it was launched” at a glance.

Session files

TOML, versioned from the first write, and meant to be edited. The layout tree is flattened into [[windows.nodes]] with generated ids; the panes are flat [[windows.panes]] tables and are the part worth hand-editing.

[[windows.panes]]
id      = '11111111-1111-1111-1111-111111111111'
kind    = 'terminal'
title   = 'build'
program = 'C:\WINDOWS\system32\cmd.exe'

Paths are written as TOML literal strings, so backslashes survive unescaped. A file that will not load is quarantined with a copy kept and WinMux refuses to start rather than silently opening empty — sessions are your data.

Open one with the disk icon’s dropdown, or winmux on the command line, or by passing it as the first argument.