setup-zellij

name	setup-zellij
description	Install Zellij and configure shell profiles to auto-launch Zellij on startup (replacing any existing herdr autostart block). Use when the user wants to install or configure Zellij's shell autostart.
disable-model-invocation	true

Task

Install zellij terminal multiplexer and configure each shell profile (PowerShell and WSL bash / zsh) to launch it automatically on startup — replacing any existing herdr autostart block installed by setup-herdr.

Steps

1. Check Zellij installation (per environment)

PowerShell: Run Get-Command zellij -ErrorAction SilentlyContinue (or zellij --version).

WSL: Run wsl -- which zellij (or wsl -- zellij --version).

If found in an environment, mark that environment "already installed" and skip to step 3 for it. If not found, continue to step 2 for that environment.

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2. Install Zellij (only after user confirmation)

These are system-level installers — always show the exact command and get the user's go-ahead before running it via Bash/PowerShell (same convention setup-herdr uses for herdr's own install script).

Windows:

winget install --id Zellij.Zellij -e

WSL/Linux:

sudo apt update && sudo apt install -y zellij

If the distribution doesn't ship zellij, install it from Cargo instead: cargo install --locked zellij (or see https://zellij.dev).

If the user declines, mark that environment "skipped (declined)" and continue with the other environment.

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3. Configure shell profiles: remove herdr autostart, add Zellij autostart

Process the following four profiles independently: PowerShell 7 ($PROFILE), Windows PowerShell, WSL bash, and WSL zsh (only if zsh is installed).

3-A. PowerShell 7 profile

1. Get the profile path from $PROFILE.

2. If the file does not exist, create it along with its parent directory.

3. Remove any existing herdr autostart block. Look for the # Auto-start herdr comment; if present, remove it together with the block that follows through the matching closing }:

   # Auto-start herdr
   if (-not $env:HERDR_ENV) {
       herdr
   }
   

   If not found, note "(nothing to remove)" and continue.

4. Read the file and check whether it contains ZELLIJ or Auto-start Zellij. If found, mark as "already configured" and skip to 3-B.

5. If not found, append the following at the end of the file:

   # Auto-start Zellij
   if (-not $env:ZELLIJ) {
       $cwd = (Get-Location).Path
       zellij options --default-shell pwsh --default-cwd $cwd
   }
   

   Why --default-cwd? On Windows, Zellij does not inherit the CWD from the launching shell, so new panes open in the user home directory. --default-cwd sets the working directory for the Zellij session directly, without altering the shell command. (pwsh = PowerShell 7 executable name on Windows)

3-B. Windows PowerShell profile

1. Build the profile path without hardcoding the username:

   $winPSProfile = Join-Path ([Environment]::GetFolderPath("MyDocuments")) "WindowsPowerShell\Microsoft.PowerShell_profile.ps1"
   

   OneDrive redirect: On systems where OneDrive syncs the Documents folder, GetFolderPath("MyDocuments") returns the OneDrive path (e.g. C:\Users\...\OneDrive\Documents\...). Do NOT hardcode C:\Users\...\Documents\... — the actual profile will be on OneDrive and the hardcoded path will silently miss it. Always use GetFolderPath or resolve the path via PowerShell before reading/editing.

2. If the parent directory (WindowsPowerShell\) does not exist, create it with New-Item -ItemType Directory -Force.

3. If the file does not exist, create it.

4. Remove any existing herdr autostart block (same # Auto-start herdr → closing } detection as 3-A). If not found, note "(nothing to remove)" and continue.

5. Read the file and check whether it contains ZELLIJ or Auto-start Zellij. If found, mark as "already configured" and skip to 3-C.

6. If not found, append the following at the end of the file:

   # Auto-start Zellij
   if (-not $env:ZELLIJ) {
       $cwd = (Get-Location).Path
       zellij options --default-shell powershell --default-cwd $cwd
   }
   

   Why --default-cwd? Same reason as 3-A. (powershell = Windows PowerShell 5.x executable name)

3-C. WSL bash profile

1. Run wsl -- test -f ~/.bashrc && echo exists to check whether ~/.bashrc exists.

2. Remove any existing herdr autostart block. Look for the # Auto-start herdr comment; if present, remove it together with the block that follows through the matching fi (e.g. wsl -- sed -i '/# Auto-start herdr/,/^fi$/d' ~/.bashrc — the block shape is fixed and known, so a range delete from the comment through the next ^fi$ is safe). If not found, note "(nothing to remove)" and continue.

3. Run wsl -- grep -q "Auto-start Zellij" ~/.bashrc to check for duplicates. (Match the literal comment marker Auto-start Zellij, not ZELLIJ — see the warning below for why.) If already present, skip to 3-D.

4. If not present, append the block by piping a PowerShell single-quoted here-string to WSL's stdin. The closing '@ must sit at column 0:

   @'
   
   # Auto-start Zellij
   if [[ -z "$ZELLIJ" ]]; then
       zellij
   fi
   '@ | wsl -- bash -c 'cat >> ~/.bashrc'
   

   ⚠️ Why a here-string, not printf? A naive wsl -- bash -c 'printf "...\$ZELLIJ..." >> ~/.bashrc' passes the format string through PowerShell → wsl → bash. The \$ZELLIJ escaping is fragile and can be stripped, writing if [[ -z "" ]] instead of if [[ -z "$ZELLIJ" ]]. Since [[ -z "" ]] is always true, Zellij then launches unconditionally — including inside an existing session — causing runaway nested Zellij/shell spawning that makes WSL unstable. A single-quoted here-string is passed verbatim (no $ expansion in PowerShell), and cat appends stdin as-is, so the $ZELLIJ guard survives. For the same reason, the dedup check in step 3 greps for Auto-start Zellij (always written) rather than ZELLIJ (lost when the guard breaks).

3-D. WSL zsh profile (only if zsh is installed)

1. Run wsl -- which zsh to check whether zsh is available. If not found, skip.

2. Run wsl -- test -f ~/.zshrc && echo exists to check whether ~/.zshrc exists.

3. Remove any existing herdr autostart block (same detection/removal as 3-C, applied to ~/.zshrc). If not found, note "(nothing to remove)" and continue.

4. Run wsl -- grep -q "generate-auto-start" ~/.zshrc first. If present, zsh already auto-starts Zellij via the official zellij setup --generate-auto-start zsh method; mark as "already configured" and skip (do not add a second manual block).

5. Otherwise run wsl -- grep -q "Auto-start Zellij" ~/.zshrc to check for the manual block. If already present, skip.

6. If neither is present, append the block via a PowerShell here-string piped to stdin (same technique and rationale as bash; the closing '@ must sit at column 0):

   @'
   
   # Auto-start Zellij
   if [[ -z "$ZELLIJ" ]]; then
       zellij
   fi
   '@ | wsl -- zsh -c 'cat >> ~/.zshrc'
   

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4. Report results (follow the Output Format below)

Output Format

## Zellij Setup

| Item                     | Status                                            |
|---------------------------|---------------------------------------------------|
| Zellij install (Windows)  | <Installed / Already installed / Skipped (declined)> |
| Zellij install (WSL/Linux)| <Installed / Already installed / Skipped (declined)> |

| Profile             | herdr block removed | Zellij autostart                                    | Profile Path |
|----------------------|----------------------|------------------------------------------------------|--------------|
| PowerShell 7         | <Yes / No / N/A>     | <Added / Already configured>                          | <$PROFILE path> |
| Windows PowerShell   | <Yes / No / N/A>     | <Added / Already configured>                          | <Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1> |
| WSL bash             | <Yes / No / N/A>     | <Added / Already configured>                          | ~/.bashrc |
| WSL zsh              | <Yes / No / N/A / zsh not installed> | <Added / Already configured / Already auto-starts via generate-auto-start> | ~/.zshrc |

### Actions taken
- <bulleted list of what was actually done>

### Next steps
- Open each shell in a new session and verify that Zellij starts automatically.
- If you are already inside a Zellij session, nested launches are suppressed via the `$ZELLIJ` variable.