Improve worktree setup safety and cross-platform compatibility

- Add validation for CONDUCTOR_ROOT_PATH environment variable
- Enhance safety checks with explicit blacklist of system directories
- Improve directory detection (symlink vs regular directory)
- Replace Python dependency with cross-platform bash+perl for path calculation
- Use absolute paths consistently to prevent symlink following
- Add detailed comments explaining each safety check

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

scripts/conductor-setup.sh

@@ -1,8 +1,20 @@
 #!/bin/bash
 set -e
 
+# Validate CONDUCTOR_ROOT_PATH is set and valid before any operations
+if [ -z "$CONDUCTOR_ROOT_PATH" ]; then
+    echo "ERROR: CONDUCTOR_ROOT_PATH environment variable is not set"
+    echo "This script must be run by Conductor with CONDUCTOR_ROOT_PATH set to the main repository path"
+    exit 1
+fi
+
+if [ ! -d "$CONDUCTOR_ROOT_PATH" ]; then
+    echo "ERROR: CONDUCTOR_ROOT_PATH ($CONDUCTOR_ROOT_PATH) is not a valid directory"
+    exit 1
+fi
+
 # Copy .env file
-cp $CONDUCTOR_ROOT_PATH/.env .env
+cp "$CONDUCTOR_ROOT_PATH/.env" .env
 
 # Setup shared dependencies via symlinks to main repo
 echo "Setting up shared node_modules and vendor directories..."
@@ -14,24 +26,67 @@ mkdir -p "$CONDUCTOR_ROOT_PATH/vendor"
 # Get current worktree path
 WORKTREE_PATH=$(pwd)
 
-# Safety check: ensure WORKTREE_PATH is valid and not a dangerous location
+# Safety check 1: ensure WORKTREE_PATH is valid
-if [ -z "$WORKTREE_PATH" ] || [ "$WORKTREE_PATH" = "/" ] || [ "$WORKTREE_PATH" = "/Users" ] || [ "$WORKTREE_PATH" = "$HOME" ]; then
+if [ -z "$WORKTREE_PATH" ]; then
-    echo "ERROR: Invalid or dangerous WORKTREE_PATH: $WORKTREE_PATH"
+    echo "ERROR: WORKTREE_PATH is empty"
     exit 1
 fi
 
-# Additional safety: ensure we're in a git worktree
+# Safety check 2: CRITICAL FIRST - blacklist system directories
+# This check runs BEFORE the positive check to prevent dangerous operations
+# even if someone misconfigures CONDUCTOR_ROOT_PATH
+case "$WORKTREE_PATH" in
+    /|/bin|/sbin|/usr|/usr/*|/etc|/etc/*|/var|/var/*|/System|/System/*|/Library|/Library/*|/Applications|/Applications/*|"$HOME")
+        echo "ERROR: WORKTREE_PATH ($WORKTREE_PATH) is in a dangerous system location"
+        exit 1
+        ;;
+esac
+
+# Safety check 3: positive check - verify we're under CONDUCTOR_ROOT_PATH
+case "$WORKTREE_PATH" in
+    "$CONDUCTOR_ROOT_PATH"|"$CONDUCTOR_ROOT_PATH"/.conductor/*)
+        # Valid: either main repo or under .conductor/
+        ;;
+    *)
+        echo "ERROR: WORKTREE_PATH ($WORKTREE_PATH) is not under CONDUCTOR_ROOT_PATH ($CONDUCTOR_ROOT_PATH)"
+        exit 1
+        ;;
+esac
+
+# Safety check 4: verify we're in a git repository
 if [ ! -f ".git" ] && [ ! -d ".git" ]; then
     echo "ERROR: Not in a git repository"
     exit 1
 fi
 
-# Remove existing directories if they exist and are not symlinks
+# Remove existing directories/symlinks if they exist
-[ -d "node_modules" ] && [ ! -L "node_modules" ] && rm -rf "$WORKTREE_PATH/node_modules"
+# For symlinks: use 'rm' without -r to remove the symlink itself (not following it)
-[ -d "vendor" ] && [ ! -L "vendor" ] && rm -rf "$WORKTREE_PATH/vendor"
+# For directories: use 'rm -rf' to remove the directory and contents
+if [ -L "node_modules" ]; then
+    # It's a symlink - remove it without following (no -r flag)
+    rm "$WORKTREE_PATH/node_modules"
+elif [ -e "node_modules" ]; then
+    # It's a regular directory or file - safe to use -rf
+    rm -rf "$WORKTREE_PATH/node_modules"
+fi
+
+if [ -L "vendor" ]; then
+    # It's a symlink - remove it without following (no -r flag)
+    rm "$WORKTREE_PATH/vendor"
+elif [ -e "vendor" ]; then
+    # It's a regular directory or file - safe to use -rf
+    rm -rf "$WORKTREE_PATH/vendor"
+fi
 
 # Calculate relative path from worktree to main repo
-RELATIVE_PATH=$(python3 -c "import os.path; print(os.path.relpath('$CONDUCTOR_ROOT_PATH', '$WORKTREE_PATH'))")
+# Use bash-native approach: try realpath first (GNU coreutils), fallback to perl
+if command -v realpath &> /dev/null && realpath --relative-to / / &> /dev/null 2>&1; then
+    # GNU coreutils realpath with --relative-to support
+    RELATIVE_PATH=$(realpath --relative-to="$WORKTREE_PATH" "$CONDUCTOR_ROOT_PATH")
+else
+    # Fallback: use perl which is standard on macOS and most Unix systems
+    RELATIVE_PATH=$(perl -e 'use File::Spec; print File::Spec->abs2rel($ARGV[0], $ARGV[1])' "$CONDUCTOR_ROOT_PATH" "$WORKTREE_PATH")
+fi
 
 # Create symlinks to main repo's node_modules and vendor
 ln -sf "$RELATIVE_PATH/node_modules" node_modules