feat: only reset deps cache when lock changes

flake.nix

@@ -58,10 +58,22 @@
 
           shellHook = ''
             echo "Setting up default dev shell..."
-            DEPS_CACHE_TMP="$(mktemp -dt gensql.query.clj.cache.XXXX)"
-            echo "Copying readonly clojure cache to read-write location at:"
+
+            DEPS_CACHE_TMP="/tmp/clojure_cache_gensql_query"
+            echo "Using read-write clojure cache at:"
             echo "$DEPS_CACHE_TMP"
-            rsync -LrltgoD --chmod=ug+w ${depsCache}/ $DEPS_CACHE_TMP/
+
+            cache_signature_file="/tmp/clojure_cache_gensql_query_signature"
+            cache_signature="$(echo ${depsCache} | tr -d '\n')"
+            last_cache_signature="$(cat $cache_signature_file | tr -d '\n')"
+
+            if [[ $cache_signature != $last_cache_signature ]]; then
+              echo -n $cache_signature > $cache_signature_file
+
+              mkdir -p $DEPS_CACHE_TMP
+              echo "Copying readonly clojure cache to read-write location"
+              rsync -LrltgoD --chmod=ug+w ${depsCache}/ $DEPS_CACHE_TMP/
+            fi
 
             export CLJ_CONFIG="$DEPS_CACHE_TMP/.clojure"
             export GITLIBS="$DEPS_CACHE_TMP/.gitlibs"