feat(sh): niri spawning script for stacking two windows of same app vertically

scripts/bin/spawn.sh

@@ -0,0 +1,82 @@
+# Spawn-or-focus logic for Niri:
+# If no "app" windows exist, spawn one.
+# If focused window is not "app", focus the first "app" instance.
+# If "app" is focused and only one instance exists, spawn + consume into stack.
+# If "app" is focused and two instances already exist, spawn a new separate one.
+# Cycle repeats: focus first > allow stack of 2 > reset on 3rd.
+
+if [ $# -lt 1 ]; then
+  echo "Usage: $0 <APP_ID> [APP_CMD]" >&2
+  exit 1
+fi
+
+APP_ID="$1"
+APP_CMD="${2:-$1}"
+
+WINDOW_DATA=$(niri msg -j windows)
+
+readarray -t APP_IDS < <(
+  echo "$WINDOW_DATA" | jq -r --arg app_id "$APP_ID" '
+    [ .[] | select(.app_id == $app_id) ]
+    | sort_by(.layout.pos_in_scrolling_layout // [0,0])
+    | .[].id
+  '
+)
+
+COUNT=${#APP_IDS[@]}
+
+FOCUSED_IS_APP=$(
+  echo "$WINDOW_DATA" | jq -r --arg app_id "$APP_ID" '
+    any(.[]; .app_id == $app_id and .is_focused)
+  '
+)
+
+spawn_normal() {
+  "$APP_CMD" &
+}
+
+spawn_and_consume() {
+  local initial_ids=("$@")
+  "$APP_CMD" &
+  local pid=$!
+
+  for _ in {1..50}; do
+    readarray -t after_ids < <(
+      niri msg -j windows | jq -r --arg app_id "$APP_ID" '
+        [ .[] | select(.app_id == $app_id) ]
+        | sort_by(.layout.pos_in_scrolling_layout // [0,0])
+        | .[].id
+      '
+    )
+
+    NEW_ID=""
+    for id in "${after_ids[@]}"; do
+      [[ " ${initial_ids[*]} " == *" $id "* ]] || NEW_ID="$id"
+    done
+
+    if [ -n "$NEW_ID" ]; then
+      niri msg action focus-window --id "${initial_ids[$((${#initial_ids[@]} - 1))]}"
+      niri msg action consume-window-into-column
+      break
+    fi
+    sleep 0.05
+  done
+
+  wait "$pid" 2>/dev/null || true
+}
+
+if ((COUNT == 0)); then
+  spawn_normal
+  exit 0
+fi
+
+if [ "$FOCUSED_IS_APP" != "true" ]; then
+  niri msg action focus-window --id "${APP_IDS[0]}"
+  exit 0
+fi
+
+if ((COUNT % 2 == 0)); then
+  spawn_normal
+else
+  spawn_and_consume "${APP_IDS[@]}"
+fi