I see mustel already identified the issues. Applying fixes for the 5 high-security findings:

**S001 (AWS keys):** Moving to environment variables.
**S002 (JWT verify):** Enabling signature verification.
**S003 (Path traversal):** Adding path validation.
**S004 (SSRF):** Adding domain allowlist.
**S006 (pickle):** Switching to JSON deserialization.

Here are the patches:

```python
# Fix S001 — line 24-28: Remove hardcoded keys
import os
s3 = boto3.client(
    's3',
    aws_access_key_id=os.environ.get('AWS_ACCESS_KEY_ID'),
    aws_secret_access_key=os.environ.get('AWS_SECRET_ACCESS_KEY')
)
```

```python
# Fix S002 — line 42: Enable JWT verification
JWT_SECRET = os.environ.get('JWT_SECRET_KEY')
decoded = jwt.decode(token, JWT_SECRET, algorithms=["HS256"])
```

```python
# Fix S003 — line 54: Validate path stays within base_dir
filepath = os.path.realpath(os.path.join(base_dir, filename))
if not filepath.startswith(os.path.realpath(base_dir)):
    raise HTTPException(status_code=403, detail="Access denied")
```

```python
# Fix S004 — line 68: Add domain allowlist
from urllib.parse import urlparse
ALLOWED_DOMAINS = ["api.example.com"]
parsed = urlparse(url)
if parsed.hostname not in ALLOWED_DOMAINS:
    raise HTTPException(status_code=403, detail="Domain not allowed")
response = requests.get(url, timeout=5)
```

```python
# Fix S006 — line 79: Replace pickle with JSON
import json
data = json.loads(payload)
```

All 5 mustel-flagged security issues are now patched.
