diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 0000000..e10098d
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,6 @@
+## 2024-05-23 - [Input Validation and Syntax Fix]
+**Vulnerability:** The `create_folder` function contained a syntax error (positional arg after keyword arg) preventing execution. Additionally, `folder_url` and `profile_id` lacked validation, potentially allowing SSRF (via non-HTTPS URLs) or path traversal/injection (via crafted profile IDs).
+**Learning:** Even simple scripts need robust input validation, especially when inputs are used to construct URLs or file paths. A syntax error can mask security issues by preventing the code from running in the first place.
+**Prevention:**
+1. Always validate external inputs against a strict allowlist (e.g., regex for IDs, protocol check for URLs).
+2. Use linters/static analysis to catch syntax errors before runtime.
diff --git a/main.py b/main.py
index 0355a19..544f2a1 100644
--- a/main.py
+++ b/main.py
@@ -18,6 +18,7 @@
 import os
 import logging
 import time
+import re
 from typing import Dict, List, Optional, Any, Set, Sequence
 
 import httpx
@@ -97,6 +98,22 @@ def _api_client() -> httpx.Client:
 _cache: Dict[str, Dict] = {}
 
 
+def validate_folder_url(url: str) -> bool:
+    """Validate that the folder URL is safe (HTTPS only)."""
+    if not url.startswith("https://"):
+        log.warning(f"Skipping unsafe or invalid URL: {url}")
+        return False
+    return True
+
+
+def validate_profile_id(profile_id: str) -> bool:
+    """Validate that the profile ID contains only safe characters."""
+    if not re.match(r"^[a-zA-Z0-9_-]+$", profile_id):
+        log.error(f"Invalid profile ID format: {profile_id}")
+        return False
+    return True
+
+
 def _api_get(client: httpx.Client, url: str) -> httpx.Response:
     """GET helper for Control-D API with retries."""
     return _retry_request(lambda: client.get(url))
@@ -227,9 +244,9 @@ def create_folder(client: httpx.Client, profile_id: str, name: str, do: int, sta
     """
     try:
         _api_post(
+            client,
             f"{API_BASE}/{profile_id}/groups",
             data={"name": name, "do": do, "status": status},
-        client,
         )
 
         # Re-fetch the list and pick the folder we just created
@@ -334,6 +351,8 @@ def sync_profile(
         # Fetch all folder data first
         folder_data_list = []
         for url in folder_urls:
+            if not validate_folder_url(url):
+                continue
             try:
                 folder_data_list.append(fetch_folder_data(url))
             except (httpx.HTTPError, KeyError) as e:
@@ -459,6 +478,10 @@ def main():
     plan: List[Dict[str, Any]] = []
     success_count = 0
     for profile_id in (profile_ids or ["dry-run-placeholder"]):
+        # Skip validation for dry-run placeholder
+        if profile_id != "dry-run-placeholder" and not validate_profile_id(profile_id):
+            continue
+
         log.info("Starting sync for profile %s", profile_id)
         if sync_profile(profile_id, folder_urls, dry_run=args.dry_run, no_delete=args.no_delete, plan_accumulator=plan):
             success_count += 1