lets try a starter

cmd.txt

@@ -0,0 +1 @@
+command cd "$(./get_input.sh)" && less input

get_input.sh

@@ -0,0 +1,21 @@
+#!/bin/bash -eu
+
+cd "$(dirname $(realpath $0))"
+
+. .env
+
+d=$(date +%d)
+
+mkdir -p d${d}
+cd d${d}
+
+[ -s input ] || curl -fsS \
+  -A "${UA}" \
+  -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' \
+  --compressed \
+  -H 'Connection: close' \
+  -H "Cookie: session=$SESSION" \
+  -o input  \
+  "https://adventofcode.com/2024/day/$(( $d + 0 ))/input"
+
+echo $(realpath .)