## What happened

`tsl abc "cmd"` exits silently having done nothing — no panes, no usage message, no error. The same applies to `tsl 0` and `tsl -3`, and to `hsl` in `default/bash/fns/herdr`.

## Cause

In `default/bash/fns/tmux`, `tsl()` never validates its first argument:

```bash
local count="$1"
...
while (( ${#panes[@]} < count )); do
```

In bash arithmetic a non-numeric string is resolved as a *variable name*; an undefined one evaluates to `0`, so the loop condition `1 < 0` is false and the function falls straight through to sending the command to the single existing pane.

There is a smaller second-order surprise: because bash resolves the value recursively, a pane count that happens to name an existing shell variable takes that variable's value. With `x=50` set, `tsl x "cmd"` creates 50 panes.

I want to be precise that this is a robustness/UX issue rather than a runaway loop — a bare typo is harmless, just silent.

## What was expected

A non-numeric or non-positive pane count prints usage and returns 1, as the other argument errors in the same file do.

## Fix

```bash
if ! [[ $count =~ ^[1-9][0-9]*$ ]]; then
  echo "Pane count must be a positive number, got: $count"
  return 1
fi
```

## System

- Omarchy 4.0.1-1
- `/usr/share/omarchy/default/bash/fns/tmux`, lines 5 and 14
- `/usr/share/omarchy/default/bash/fns/herdr` (`hsl`) has the same unchecked loop