#!/usr/bin/env python3
"""
PreToolUse hook to automatically approve Write operations to the temp/ directory.
This hook is designed to be used in skill frontmatter to eliminate permission
prompts when skills create files in their designated temp/ output directories.
Usage in skill frontmatter:
hooks:
PreToolUse:
- matcher: "Write"
hooks:
- type: command
command: "$CLAUDE_PROJECT_DIR/.claude/hooks/allow-temp-writes.py"
"""
import json
import os
import sys
def is_temp_path(file_path: str) -> bool:
"""
Check if the file path is within the temp/ directory.
Handles various path formats:
- temp/file.md (relative from project root)
- ./temp/file.md (explicit relative)
- /absolute/path/to/project/temp/file.md (absolute within project)
Security: Rejects paths with:
- Absolute paths outside the project directory
- Path traversal (../other-project/temp/data.json)
- Parent references (temp/../../../etc/shadow)
"""
if not file_path:
return False
# Normalize path separators for consistency
normalized = file_path.replace("\\", "/")
# Reject any path containing parent directory references
if ".." in normalized:
return False
# Handle absolute paths: allow if within CLAUDE_PROJECT_DIR/temp/
if normalized.startswith("/"):
project_dir = os.environ.get("CLAUDE_PROJECT_DIR", "")
if project_dir:
project_temp = f"{project_dir.rstrip('/')}/temp/"
if normalized.startswith(project_temp):
return True
return False
# Only allow paths that start with temp/ or ./temp/
# This ensures we're writing files within the temp/ directory
return normalized.startswith("temp/") or normalized.startswith("./temp/")
def main():
try:
# Read hook input from stdin
data = json.load(sys.stdin)
# Extract file path from tool input
file_path = data.get("tool_input", {}).get("file_path", "")
# Check if the file path is within temp/ directory
if is_temp_path(file_path):
# Auto-approve the write operation
output = {
"hookSpecificOutput": {
"hookEventName": "PreToolUse",
"permissionDecision": "allow",
"permissionDecisionReason": "Auto-approved: skill writes to temp/ directory",
}
}
print(json.dumps(output))
# For non-temp paths, exit cleanly without output
# This allows normal permission flow to proceed
sys.exit(0)
except Exception:
# On any error, exit cleanly to let normal permission flow proceed
# We don't want to break tool execution due to hook failures
sys.exit(0)
if __name__ == "__main__":
main()
