feat(tool): fs_write ask confirmation for existing files

tools/fs_write.sh

@@ -11,8 +11,13 @@ set -e
 ROOT_DIR="${LLM_ROOT_DIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)}"
 
 main() {
-    "$ROOT_DIR/utils/guard_path.sh" "$argc_path" "Write '$argc_path'?"
-    mkdir -p "$(dirname "$argc_path")"
+    if [[ -f "$argc_path" ]]; then
+        printf "%s" "$argc_contents" | git diff --no-index "$argc_path" - || true
+        "$ROOT_DIR/utils/guard_operation.sh" "Apply changes?"
+    else
+        "$ROOT_DIR/utils/guard_path.sh" "$argc_path" "Write '$argc_path'?"
+        mkdir -p "$(dirname "$argc_path")"
+    fi
     printf "%s" "$argc_contents" > "$argc_path"
     echo "The contents written to: $argc_path" >> "$LLM_OUTPUT"
 }