diff --git a/VERSION b/VERSION
index 21e8796..ee90284 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.0.3
+1.0.4
diff --git a/install.sh b/install.sh
index af53631..3d24612 100755
--- a/install.sh
+++ b/install.sh
@@ -1,6 +1,14 @@
 #!/usr/bin/env bash
 # install.sh — Bootstrap mbp on a fresh Mac
 # Usage: bash <(curl -fsSL https://raw.githubusercontent.com/devizerio/mbp/main/install.sh)
+#
+# Security note: This script is fetched over HTTPS from GitHub. It trusts:
+#   - GitHub's TLS infrastructure for transport security
+#   - The devizerio/mbp repository for code integrity
+# For additional verification, download first and inspect:
+#   curl -fsSL https://raw.githubusercontent.com/devizerio/mbp/main/install.sh -o install.sh
+#   shasum -a 256 install.sh   # compare with published hash
+#   bash install.sh
 set -euo pipefail
 
 MBP_REPO="${MBP_REPO:-$HOME/.mbp/repo}"
diff --git a/lib/audit.sh b/lib/audit.sh
index 22c837e..1d73ffc 100644
--- a/lib/audit.sh
+++ b/lib/audit.sh
@@ -158,9 +158,27 @@ audit_macos_defaults() {
   # Parse apply_default lines: apply_default "domain" "key" "type" "value"
   while IFS= read -r line; do
     local domain key type expected_value
-    # Extract quoted args using parameter expansion
-    eval "set -- $(echo "$line" | sed 's/apply_default //')" 2>/dev/null || continue
-    domain="$1" key="$2" type="$3" expected_value="$4"
+    # Safely extract quoted args without eval
+    local args_str
+    args_str=$(echo "$line" | sed 's/^[[:space:]]*apply_default[[:space:]]*//')
+    # Parse space-separated quoted arguments safely using read
+    local -a args=()
+    while [[ -n "$args_str" ]]; do
+      args_str="${args_str#"${args_str%%[![:space:]]*}"}"  # trim leading space
+      [ -z "$args_str" ] && break
+      if [[ "$args_str" == \"* ]]; then
+        # Quoted argument — extract up to closing quote
+        args_str="${args_str#\"}"
+        args+=("${args_str%%\"*}")
+        args_str="${args_str#*\"}"
+      else
+        # Unquoted argument
+        args+=("${args_str%% *}")
+        args_str="${args_str#* }"
+        [[ "$args_str" == "${args[${#args[@]}-1]}" ]] && args_str=""
+      fi
+    done
+    domain="${args[0]:-}" key="${args[1]:-}" type="${args[2]:-}" expected_value="${args[3]:-}"
 
     [ -z "$domain" ] || [ -z "$key" ] && continue
 
diff --git a/lib/profile.sh b/lib/profile.sh
index b22345d..96f44fb 100644
--- a/lib/profile.sh
+++ b/lib/profile.sh
@@ -34,9 +34,15 @@ profile_load() {
         fi
         ;;
       modules)
-        # Split on commas, trim each value
+        # Split on commas, trim each value, validate names (alphanumeric + hyphens only)
         MBP_PROFILE_MODULES=$(echo "$raw_val" | tr ',' '\n' | \
           sed 's/^[[:space:]]*//;s/[[:space:]]*$//' | tr '\n' ' ' | sed 's/ $//')
+        for _mod in $MBP_PROFILE_MODULES; do
+          if ! echo "$_mod" | grep -qE '^[a-zA-Z0-9_-]+$'; then
+            printf "profile: invalid module name '%s' — only alphanumeric, hyphens, underscores allowed\n" "$_mod" >&2
+            return 1
+          fi
+        done
         ;;
       brewfiles)
         MBP_PROFILE_BREWFILES=$(echo "$raw_val" | tr ',' '\n' | \
diff --git a/lib/state.sh b/lib/state.sh
index a265ce7..263b411 100644
--- a/lib/state.sh
+++ b/lib/state.sh
@@ -9,6 +9,19 @@ MBP_STATE_TXT="${MBP_STATE_DIR}/state.txt"
 MBP_STATE_SCHEMA_VERSION=1
 
 mkdir -p "$MBP_STATE_DIR"
+chmod 700 "$MBP_STATE_DIR"
+
+# Track temp files for cleanup on exit
+_MBP_STATE_TMPFILES=()
+_mbp_state_cleanup() { rm -f "${_MBP_STATE_TMPFILES[@]}" 2>/dev/null; }
+trap _mbp_state_cleanup EXIT
+
+# Safe mktemp that registers for cleanup
+_mbp_mktemp() {
+  local f; f=$(mktemp)
+  _MBP_STATE_TMPFILES+=("$f")
+  echo "$f"
+}
 
 # === Plain-text state (modules 01-02) ===
 # Format: module=status:exit_code:timestamp
@@ -93,7 +106,7 @@ state_migrate_from_txt() {
       extra=$(jq -n --argjson count "$pkg_count" '{"packages": $count}')
     fi
 
-    local tmp; tmp=$(mktemp)
+    local tmp; tmp=$(_mbp_mktemp)
     jq --arg module "$module" \
        --arg status "$status" \
        --argjson exit_code "${exit_code:-0}" \
@@ -113,7 +126,7 @@ state_set_module_ok() {
   command -v jq >/dev/null 2>&1 || return 1
   [ -f "$MBP_STATE_JSON" ] || state_init_json
   local ts; ts=$(date -u +%Y-%m-%dT%H:%M:%SZ)
-  local tmp; tmp=$(mktemp)
+  local tmp; tmp=$(_mbp_mktemp)
   jq --arg module "$module" --arg ts "$ts" \
     '.modules[$module] = (.modules[$module] // {} | . + {status: "ok", exit_code: 0, ran_at: $ts})' \
     "$MBP_STATE_JSON" > "$tmp" && mv "$tmp" "$MBP_STATE_JSON"
@@ -124,7 +137,7 @@ state_set_module_error() {
   command -v jq >/dev/null 2>&1 || return 1
   [ -f "$MBP_STATE_JSON" ] || state_init_json
   local ts; ts=$(date -u +%Y-%m-%dT%H:%M:%SZ)
-  local tmp; tmp=$(mktemp)
+  local tmp; tmp=$(_mbp_mktemp)
   jq --arg module "$module" --arg ts "$ts" \
      --argjson exit_code "$exit_code" --arg error "$error_msg" \
     '.modules[$module] = (.modules[$module] // {} | . + {status: "error", exit_code: $exit_code, ran_at: $ts, error: $error})' \
@@ -135,7 +148,7 @@ state_set_module_meta() {
   local module="$1" key="$2" value="$3"
   command -v jq >/dev/null 2>&1 || return 1
   [ -f "$MBP_STATE_JSON" ] || return 1
-  local tmp; tmp=$(mktemp)
+  local tmp; tmp=$(_mbp_mktemp)
   # value may be a JSON fragment (array, number) or a plain string
   if echo "$value" | jq . >/dev/null 2>&1; then
     jq --arg module "$module" --arg key "$key" --argjson val "$value" \
@@ -165,7 +178,7 @@ state_set_profile() {
   local profile="$1"
   command -v jq >/dev/null 2>&1 || return 1
   [ -f "$MBP_STATE_JSON" ] || state_init_json "$profile"
-  local tmp; tmp=$(mktemp)
+  local tmp; tmp=$(_mbp_mktemp)
   jq --arg profile "$profile" '.profile = $profile' "$MBP_STATE_JSON" > "$tmp" && mv "$tmp" "$MBP_STATE_JSON"
 }
 
@@ -173,7 +186,7 @@ state_set_last_run() {
   command -v jq >/dev/null 2>&1 || return 1
   [ -f "$MBP_STATE_JSON" ] || return 1
   local ts; ts=$(date -u +%Y-%m-%dT%H:%M:%SZ)
-  local tmp; tmp=$(mktemp)
+  local tmp; tmp=$(_mbp_mktemp)
   jq --arg ts "$ts" '.last_run = $ts' "$MBP_STATE_JSON" > "$tmp" && mv "$tmp" "$MBP_STATE_JSON"
 }
 
@@ -207,7 +220,7 @@ state_check_schema() {
     printf "state: schema v%s detected, expected v%s — migrating...\n" \
       "$current_schema" "$MBP_STATE_SCHEMA_VERSION"
     # Future migration functions go here
-    local tmp; tmp=$(mktemp)
+    local tmp; tmp=$(_mbp_mktemp)
     jq --argjson v "$MBP_STATE_SCHEMA_VERSION" '.schema_version = $v' \
       "$MBP_STATE_JSON" > "$tmp" && mv "$tmp" "$MBP_STATE_JSON"
   fi
diff --git a/modules/01-xcode.sh b/modules/01-xcode.sh
index fd82801..03d985f 100755
--- a/modules/01-xcode.sh
+++ b/modules/01-xcode.sh
@@ -30,7 +30,9 @@ until xcode-select -p >/dev/null 2>&1; do
 done
 
 # Accept license
-sudo xcodebuild -license accept 2>/dev/null || true
+if ! sudo xcodebuild -license accept 2>/dev/null; then
+  mbp_log_warn "Could not auto-accept Xcode license — you may need to run: sudo xcodebuild -license accept"
+fi
 
 mbp_log_ok "Xcode Command Line Tools installed: $(xcode-select -p)"
 state_txt_set "xcode" "ok" "0"
diff --git a/modules/02-homebrew.sh b/modules/02-homebrew.sh
index 8bd2730..632a7d4 100755
--- a/modules/02-homebrew.sh
+++ b/modules/02-homebrew.sh
@@ -37,8 +37,10 @@ for bf in $BREWFILES; do
   BFPATH="$BREWFILE_DIR/Brewfile.$bf"
   if [ -f "$BFPATH" ]; then
     mbp_log_step "Bundling: Brewfile.$bf"
-    brew bundle --file="$BFPATH" --no-upgrade 2>&1 | \
-      grep -v "^Using " | grep -v "^Homebrew Bundle complete" || true
+    if ! brew bundle --file="$BFPATH" --no-upgrade 2>&1 | \
+      grep -v "^Using " | grep -v "^Homebrew Bundle complete"; then
+      mbp_log_warn "brew bundle returned non-zero for Brewfile.$bf — some packages may have failed"
+    fi
   else
     mbp_log_warn "Brewfile.$bf not found, skipping"
   fi
diff --git a/modules/03-shell.sh b/modules/03-shell.sh
index 8ec5551..d1c4bd2 100755
--- a/modules/03-shell.sh
+++ b/modules/03-shell.sh
@@ -21,9 +21,10 @@ fi
 # Ensure Homebrew zsh is in /etc/shells
 ZSH_BIN="$(brew --prefix 2>/dev/null)/bin/zsh"
 if [ -f "$ZSH_BIN" ]; then
-  if ! grep -qF "$ZSH_BIN" /etc/shells 2>/dev/null; then
+  # Validate the path contains no newlines or special characters before writing to /etc/shells
+  if [[ "$ZSH_BIN" =~ ^[a-zA-Z0-9/_.-]+$ ]] && ! grep -qF "$ZSH_BIN" /etc/shells 2>/dev/null; then
     mbp_log_step "Adding Homebrew zsh to /etc/shells..."
-    echo "$ZSH_BIN" | sudo tee -a /etc/shells >/dev/null
+    printf '%s\n' "$ZSH_BIN" | sudo tee -a /etc/shells >/dev/null
   fi
 
   # Change default shell if needed
diff --git a/modules/04-mise.sh b/modules/04-mise.sh
index 019f63f..41a12ae 100755
--- a/modules/04-mise.sh
+++ b/modules/04-mise.sh
@@ -34,9 +34,11 @@ for tool_spec in $MISE_TOOLS; do
   tool_name="${tool_spec%%@*}"
   tool_version="${tool_spec#*@}"
   mbp_log_step "Ensuring ${tool_name}@${tool_version}..."
-  mise install "${tool_spec}" 2>&1 | grep -v "^mise " | tail -3 | while IFS= read -r line; do
+  if ! mise install "${tool_spec}" 2>&1 | grep -v "^mise " | tail -3 | while IFS= read -r line; do
     [ -n "$line" ] && mbp_log_step "$line"
-  done
+  done; then
+    mbp_log_warn "mise install ${tool_spec} may have failed"
+  fi
   mise use --global "${tool_spec}" 2>/dev/null || true
 done
 
diff --git a/modules/05-dotfiles.sh b/modules/05-dotfiles.sh
index fde51ca..705e839 100755
--- a/modules/05-dotfiles.sh
+++ b/modules/05-dotfiles.sh
@@ -34,17 +34,22 @@ link_dotfile() {
     return
   fi
 
-  # Backup existing non-symlink file
+  # Ensure parent directory exists
+  mkdir -p "$(dirname "$dst")"
+
+  # Backup existing regular file atomically (copy then link in one step)
   if [ -f "$dst" ] && [ ! -L "$dst" ]; then
     mkdir -p "$BACKUP_DIR"
     cp "$dst" "$BACKUP_DIR/$(basename "$dst")"
     mbp_log_step "backed up: ~/${dst_name} → $BACKUP_DIR"
   fi
 
-  # Ensure parent directory exists
-  mkdir -p "$(dirname "$dst")"
-
-  ln -sf "$src" "$dst"
+  # Atomic symlink: create temp link then rename over destination
+  local tmp_link
+  tmp_link=$(mktemp "${dst}.mbp.XXXXXX")
+  rm -f "$tmp_link"
+  ln -s "$src" "$tmp_link"
+  mv -f "$tmp_link" "$dst"
   mbp_log_ok "linked: ~/${dst_name}"
   LINKED=$((LINKED + 1))
 }
diff --git a/modules/07-ssh.sh b/modules/07-ssh.sh
index 442e298..02f2d75 100755
--- a/modules/07-ssh.sh
+++ b/modules/07-ssh.sh
@@ -19,7 +19,9 @@ for key in "$SSH_DIR"/*; do
   [[ "$(basename "$key")" == "config"* ]] && continue
   [[ "$(basename "$key")" == "environment" ]] && continue
 
-  chmod 600 "$key"
+  if ! chmod 600 "$key"; then
+    mbp_log_warn "failed to set permissions on $(basename "$key")"
+  fi
   KEY_COUNT=$((KEY_COUNT + 1))
   mbp_log_step "permissions 600: $(basename "$key")"
 
@@ -36,6 +38,22 @@ for key in "$SSH_DIR"/*; do
   esac
 done
 
+# Warn about weak key types
+if [ -n "$GITHUB_KEY" ] && [ -f "${GITHUB_KEY}.pub" ]; then
+  KEY_TYPE=$(ssh-keygen -l -f "${GITHUB_KEY}.pub" 2>/dev/null | awk '{print $4}' | tr -d '()')
+  KEY_BITS=$(ssh-keygen -l -f "${GITHUB_KEY}.pub" 2>/dev/null | awk '{print $1}')
+  case "$KEY_TYPE" in
+    DSA)
+      mbp_log_warn "SSH key $(basename "$GITHUB_KEY") uses DSA which is deprecated — generate an ed25519 key"
+      ;;
+    RSA)
+      if [ "${KEY_BITS:-0}" -lt 3072 ]; then
+        mbp_log_warn "SSH key $(basename "$GITHUB_KEY") is RSA ${KEY_BITS}-bit — consider ed25519 or RSA 4096"
+      fi
+      ;;
+  esac
+fi
+
 # Ensure config.d directory for per-client/per-project includes
 mkdir -p "${SSH_DIR}/config.d"
 
@@ -47,7 +65,7 @@ if [ -n "$GITHUB_KEY" ]; then
 Host github.com
     HostName github.com
     User git
-    IdentityFile ${GITHUB_KEY}
+    IdentityFile "${GITHUB_KEY}"
 EOF
   mbp_log_ok "GitHub SSH: using $(basename "$GITHUB_KEY")"
 elif [ ! -f "$GITHUB_CONF" ]; then
diff --git a/modules/10-ai-tools.sh b/modules/10-ai-tools.sh
index 1e32a1f..9333945 100755
--- a/modules/10-ai-tools.sh
+++ b/modules/10-ai-tools.sh
@@ -28,7 +28,7 @@ else
   else
     mbp_log_warn "npm not found — install node (module 04) and re-run"
     state_set_module_error "ai-tools" "1" "npm not available for Claude Code install"
-    exit 1
+    return 1
   fi
 fi
 
diff --git a/modules/11-macos-defaults.sh b/modules/11-macos-defaults.sh
index f6a3f9f..d01f98d 100755
--- a/modules/11-macos-defaults.sh
+++ b/modules/11-macos-defaults.sh
@@ -74,6 +74,13 @@ mbp_log_step "Activity Monitor..."
 apply_default "com.apple.ActivityMonitor" "OpenMainWindow" "bool" "true"
 apply_default "com.apple.ActivityMonitor" "ShowCategory"   "int"  "0"
 
+mbp_log_step "Security..."
+# Enable macOS firewall
+sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on 2>/dev/null || true
+# Require password immediately after sleep/screen saver
+apply_default "com.apple.screensaver" "askForPassword"      "int" "1"
+apply_default "com.apple.screensaver" "askForPasswordDelay"  "int" "0"
+
 # Restart affected system processes
 mbp_log_step "Restarting system services..."
 killall Dock    2>/dev/null || true
diff --git a/profiles/devizer-full.conf b/profiles/devizer-full.conf
index c6760a4..3e3a5df 100644
--- a/profiles/devizer-full.conf
+++ b/profiles/devizer-full.conf
@@ -5,4 +5,4 @@
 format = 1
 modules = xcode,homebrew,shell,mise,dotfiles,git,ssh,secrets,docker,ai-tools,macos-defaults,apps,dev-dirs
 brewfiles = core,dev,ai,apps,personal
-mise_tools = node@22,ruby@3.3,python@3.12,bun@latest
+mise_tools = node@22,ruby@3.3,python@3.12,bun@1.2
diff --git a/profiles/personal.conf b/profiles/personal.conf
index 076d6a8..977a547 100644
--- a/profiles/personal.conf
+++ b/profiles/personal.conf
@@ -4,4 +4,4 @@
 format = 1
 modules = xcode,homebrew,shell,mise,dotfiles,git,ssh,secrets,docker,ai-tools,macos-defaults,apps,dev-dirs
 brewfiles = core,dev,ai,apps,personal
-mise_tools = node@22,ruby@3.3,python@3.12,bun@latest
+mise_tools = node@22,ruby@3.3,python@3.12,bun@1.2