chore: add pre-commit hook to prevent sensitive file commits

- Whitelist approach: only known safe extensions allowed (.rs, .toml, .yml, etc.)
- Block sensitive patterns (.env, .key, .pem, secrets, credentials)
- Warn but allow .md files
- Check only NEW files, modifications to tracked files always allowed
- Block large files (>5MB) with warning
- Run cargo fmt check on Rust files
- Update CONTRIBUTING.md with hook setup instructions

.githooks/pre-commit

@@ -0,0 +1,142 @@
+#!/bin/bash
+# Pre-commit hook to prevent accidental commits of sensitive files
+# Enable: git config core.hooksPath .githooks
+
+set -e
+
+RED='\033[0;31m'
+YELLOW='\033[1;33m'
+GREEN='\033[0;32m'
+NC='\033[0m'
+
+# Allowed file extensions (whitelist)
+ALLOWED_EXTENSIONS=(
+    '\.rs$'
+    '\.toml$'
+    '\.lock$'
+    '\.yml$'
+    '\.yaml$'
+    '\.json$'
+    '\.sh$'
+    '\.html$'
+    '\.css$'
+    '\.js$'
+    '\.gitignore$'
+    '\.dockerignore$'
+    'Dockerfile$'
+    'LICENSE$'
+    'Makefile$'
+)
+
+# Extensions that trigger a warning (not blocked)
+WARN_EXTENSIONS=(
+    '\.md$'
+)
+
+# Always blocked patterns (regardless of extension)
+BLOCKED_PATTERNS=(
+    '\.env$'
+    '\.env\.'
+    '\.key$'
+    '\.pem$'
+    '\.p12$'
+    '\.pfx$'
+    '\.htpasswd$'
+    'secret'
+    'credential'
+    'password'
+    '\.bak$'
+    '\.swp$'
+    '\.swo$'
+    'node_modules/'
+    'target/debug/'
+    '\.DS_Store'
+)
+
+# Get staged files (only NEW files, not already tracked)
+STAGED_FILES=$(git diff --cached --name-only --diff-filter=A)
+
+if [ -z "$STAGED_FILES" ]; then
+    # No new files, only modifications to existing - allow
+    exit 0
+fi
+
+# Build patterns
+ALLOWED_PATTERN=$(IFS='|'; echo "${ALLOWED_EXTENSIONS[*]}")
+WARN_PATTERN=$(IFS='|'; echo "${WARN_EXTENSIONS[*]}")
+BLOCKED_PATTERN=$(IFS='|'; echo "${BLOCKED_PATTERNS[*]}")
+
+# Check for blocked patterns first
+BLOCKED_FILES=$(echo "$STAGED_FILES" | grep -iE "$BLOCKED_PATTERN" || true)
+
+if [ -n "$BLOCKED_FILES" ]; then
+    echo -e "${RED}BLOCKED: Suspicious files detected in commit${NC}"
+    echo ""
+    echo -e "${YELLOW}Files:${NC}"
+    echo "$BLOCKED_FILES" | sed 's/^/  - /'
+    echo ""
+    echo "If intentional, use: git commit --no-verify"
+    exit 1
+fi
+
+# Check for files with unknown extensions
+UNKNOWN_FILES=""
+WARN_FILES=""
+
+while IFS= read -r file; do
+    [ -z "$file" ] && continue
+
+    if echo "$file" | grep -qE "$BLOCKED_PATTERN"; then
+        continue  # Already handled above
+    elif echo "$file" | grep -qE "$WARN_PATTERN"; then
+        WARN_FILES="$WARN_FILES$file"$'\n'
+    elif ! echo "$file" | grep -qE "$ALLOWED_PATTERN"; then
+        UNKNOWN_FILES="$UNKNOWN_FILES$file"$'\n'
+    fi
+done <<< "$STAGED_FILES"
+
+# Warn about .md files
+if [ -n "$WARN_FILES" ]; then
+    echo -e "${YELLOW}WARNING: Markdown files in commit:${NC}"
+    echo "$WARN_FILES" | sed '/^$/d' | sed 's/^/  - /'
+    echo ""
+fi
+
+# Block unknown extensions
+if [ -n "$UNKNOWN_FILES" ]; then
+    echo -e "${RED}BLOCKED: Files with unknown extensions:${NC}"
+    echo "$UNKNOWN_FILES" | sed '/^$/d' | sed 's/^/  - /'
+    echo ""
+    echo "Allowed extensions: rs, toml, lock, yml, yaml, json, sh, html, css, js, md"
+    echo "If intentional, use: git commit --no-verify"
+    exit 1
+fi
+
+# Check for large files (>5MB)
+LARGE_FILES=$(echo "$STAGED_FILES" | while read f; do
+    if [ -f "$f" ]; then
+        size=$(stat -f%z "$f" 2>/dev/null || stat -c%s "$f" 2>/dev/null || echo 0)
+        if [ "$size" -gt 5242880 ]; then
+            echo "$f ($(numfmt --to=iec $size 2>/dev/null || echo "${size}B"))"
+        fi
+    fi
+done)
+
+if [ -n "$LARGE_FILES" ]; then
+    echo -e "${YELLOW}WARNING: Large files (>5MB) in commit:${NC}"
+    echo "$LARGE_FILES" | sed 's/^/  - /'
+    echo ""
+fi
+
+# Run cargo fmt check if Rust files changed
+if git diff --cached --name-only | grep -q '\.rs$'; then
+    if command -v cargo &> /dev/null; then
+        if ! cargo fmt --check &> /dev/null; then
+            echo -e "${RED}BLOCKED: cargo fmt check failed${NC}"
+            echo "Run: cargo fmt"
+            exit 1
+        fi
+    fi
+fi
+
+exit 0

CONTRIBUTING.md

@@ -14,6 +14,9 @@ Thank you for your interest in contributing to NORA!
 # Install Rust (if needed)
 curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
 
+# Enable pre-commit hooks (important!)
+git config core.hooksPath .githooks
+
 # Build
 cargo build