Install Elsewhen, the world clock plugin, by default

Elsewhen (omacom.elsewhen) arrives as the elsewhen package under
/usr/share/omarchy/plugins, the packaged root the shell scans between its
bundled plugins and the user's. It opens the right section of the default
bar, just before the tray, and a migration installs the package, writes the
widget into a customized shell.json in the same spot, and retires a pristine
pre-package clone of the upstream repo that the package now shadows.

migrations/1789581661.sh

@@ -0,0 +1,85 @@
+echo "Install Elsewhen, the world clock plugin"
+
+# Elsewhen ships as the elsewhen package rather than in this checkout; pacman
+# puts it under /usr/share/omarchy/plugins, where the shell looks next to its
+# bundled plugins. A package the mirror does not carry yet fails the migration
+# on purpose: nothing before this line has changed anything, and the runner
+# retries it on the next update or login rather than quietly leaving the
+# machine without the plugin.
+omarchy-pkg-add elsewhen
+
+# A shell that already knows the packaged root (dev-linked, or restarted
+# since) picks the plugin up here; the one an update runs under predates it
+# and is replaced by omarchy-update-restart right after the migrations.
+omarchy-shell -q shell rescanPlugins || true
+
+# Before the package, the README had users run
+# `omarchy plugin add https://github.com/omacom/elsewhen.git`, which left a
+# git clone under ~/.config/omarchy/plugins. The packaged copy now shadows
+# it: the shell logs a rejection on every scan, and `omarchy plugin update`
+# keeps pulling a checkout nothing loads. A pristine clone of the upstream
+# repo is retired the way `omarchy plugin remove` retires one (the repo
+# remains upstream). Anything else -- a symlink, a plain directory, local
+# changes, a fork, a checkout git cannot read -- is the user's and stays. This
+# runs only once the package is in place, so the plugin never leaves a
+# machine; its id stays in shell.json either way, which is what keeps it
+# enabled. The shell an update runs under predates the packaged root, and it
+# watches this directory: dropping the checkout empties the widget's slot in
+# that shell until omarchy-update-restart replaces it a few steps later with
+# one that finds the package. A one-time gap of a few minutes, during the
+# update itself.
+upstream_checkout() {
+  local dir="$1" origin status
+  [[ -d $dir && ! -L $dir && -d $dir/.git ]] || return 1
+  origin=$(git -C "$dir" remote get-url origin 2>/dev/null) || return 1
+  origin=${origin,,}
+  origin=${origin%/}
+  origin=${origin%.git}
+  [[ $origin =~ ^([a-z+]+://)?([^/@]+@)?github\.com[/:]omacom/elsewhen$ ]] || return 1
+  status=$(git -C "$dir" status --porcelain 2>/dev/null) || return 1
+  [[ -z $status ]]
+}
+
+checkout="$HOME/.config/omarchy/plugins/omacom.elsewhen"
+if [[ -e $checkout || -L $checkout ]]; then
+  if upstream_checkout "$checkout"; then
+    rm -rf "$checkout"
+    echo "Retired the omacom.elsewhen checkout at $checkout in favour of the elsewhen package."
+  else
+    echo "The elsewhen package takes precedence over $checkout, which is left as it is."
+  fi
+fi
+
+# The widget opens the right section of the default bar, just before the
+# tray, which a machine without a shell.json takes on as soon as the shell
+# restarts. A customized bar gets the entry written into its file rather than
+# placed over IPC: the shell this runs under cannot see a widget its scan
+# never reached and would refuse it, whereas the file it hot-reloads carries
+# the entry through to the restart. A bar that already carries the widget
+# keeps it where the user put it.
+source omarchy-shell-config
+
+[[ -s $CONFIG_FILE ]] || exit 0
+# A file the shell cannot read is left for its owner to repair.
+jq empty "$CONFIG_FILE" 2>/dev/null || exit 0
+
+entry_id='def entry_id: if type == "object" then (.id // "" | tostring) else tostring end;'
+
+if jq -e "$entry_id"'
+  any((.bar.layout // {} | .left, .center, .right | arrays)[]; entry_id == "omacom.elsewhen")
+' "$CONFIG_FILE" >/dev/null; then
+  exit 0
+fi
+
+commit "$NORMALIZE | $entry_id"'
+  def ids: map(entry_id);
+  def insert_at($section; $index):
+    .bar.layout[$section] = .bar.layout[$section][:$index] + [{id: "omacom.elsewhen"}] + .bar.layout[$section][$index:];
+  . as $config
+  | (["left", "center", "right"] | map(select($config.bar.layout[.] | ids | index("omarchy.tray") != null)) | first) as $section
+  | if $section != null then
+      insert_at($section; .bar.layout[$section] | ids | index("omarchy.tray"))
+    else
+      insert_at("right"; 0)
+    end
+'