diff --git a/nix/shell.nix b/nix/shell.nix
index f6de96cb..34f29da3 100644
--- a/nix/shell.nix
+++ b/nix/shell.nix
@@ -282,45 +282,53 @@ mkShell {
     # Ensure Erlang can find NIF libraries
     export ERL_AFLAGS="-kernel shell_history enabled"
 
-    # Install Hex and Rebar3 if not already installed
-    mix local.hex --force --if-missing > /dev/null 2>&1
-    mix local.rebar --force --if-missing > /dev/null 2>&1
+    # Skip heavy setup when running inside direnv (DIRENV_DIR is set).
+    # direnv evaluates the shellHook to load env vars only; running mix,
+    # starting services, or installing pre-commit hooks would block the
+    # prompt and cause nix profile cleanup hangs on macOS.
+    if [ -z "$DIRENV_DIR" ]; then
+      # Running in nix develop (interactive shell)
 
-    # Auto-start services on first shell entry
-    if [ ! -f "${servicesFlag}" ]; then
-      ${startServices}/bin/start-services
+      # Install Hex and Rebar3 if not already installed
+      mix local.hex --force --if-missing > /dev/null 2>&1
+      mix local.rebar --force --if-missing > /dev/null 2>&1
 
-      # Run migrations if databases exist and Mix deps are available
-      if [ -d "deps" ] && mix ecto.migrate 2>/dev/null; then
-        echo "✓ Database migrations applied"
+      # Auto-start services on first shell entry
+      if [ ! -f "${servicesFlag}" ]; then
+        ${startServices}/bin/start-services
+
+        # Run migrations if databases exist and Mix deps are available
+        if [ -d "deps" ] && mix ecto.migrate 2>/dev/null; then
+          echo "✓ Database migrations applied"
+        fi
       fi
+
+      # Install pre-commit hooks
+      ${pre-commit-check.shellHook}
+
+      # Welcome message
+      echo ""
+      echo -e "''${BLUE}╔═══════════════════════════════════════════════════════════╗''${NC}"
+      echo -e "''${BLUE}║                                                           ║''${NC}"
+      echo -e "''${BLUE}║''${NC}  ''${GREEN}Towerops Development Environment''${NC}                     ''${BLUE}║''${NC}"
+      echo -e "''${BLUE}║                                                           ║''${NC}"
+      echo -e "''${BLUE}╚═══════════════════════════════════════════════════════════╝''${NC}"
+      echo ""
+      echo -e "''${GREEN}Available commands:''${NC}"
+      echo "  mix phx.server       - Start Phoenix development server"
+      echo "  mix test             - Run test suite"
+      echo "  mix precommit        - Run pre-commit checks (format, credo, test)"
+      echo "  start-services       - Start PostgreSQL and Redis"
+      echo "  stop-services        - Stop PostgreSQL and Redis"
+      echo "  mix ecto.reset       - Reset database (drop, create, migrate, seed)"
+      echo ""
+      echo -e "''${GREEN}Services:''${NC}"
+      echo "  PostgreSQL: ${pgHost}:${pgPort}"
+      echo "  Redis:      ${pgHost}:${redisPort}"
+      echo ""
+      echo -e "''${GREEN}Documentation:''${NC}"
+      echo "  See CLAUDE.md and docs/nix.md for more information"
+      echo ""
     fi
-
-    # Install pre-commit hooks
-    ${pre-commit-check.shellHook}
-
-    # Welcome message
-    echo ""
-    echo -e "''${BLUE}╔═══════════════════════════════════════════════════════════╗''${NC}"
-    echo -e "''${BLUE}║                                                           ║''${NC}"
-    echo -e "''${BLUE}║''${NC}  ''${GREEN}Towerops Development Environment''${NC}                     ''${BLUE}║''${NC}"
-    echo -e "''${BLUE}║                                                           ║''${NC}"
-    echo -e "''${BLUE}╚═══════════════════════════════════════════════════════════╝''${NC}"
-    echo ""
-    echo -e "''${GREEN}Available commands:''${NC}"
-    echo "  mix phx.server       - Start Phoenix development server"
-    echo "  mix test             - Run test suite"
-    echo "  mix precommit        - Run pre-commit checks (format, credo, test)"
-    echo "  start-services       - Start PostgreSQL and Redis"
-    echo "  stop-services        - Stop PostgreSQL and Redis"
-    echo "  mix ecto.reset       - Reset database (drop, create, migrate, seed)"
-    echo ""
-    echo -e "''${GREEN}Services:''${NC}"
-    echo "  PostgreSQL: ${pgHost}:${pgPort}"
-    echo "  Redis:      ${pgHost}:${redisPort}"
-    echo ""
-    echo -e "''${GREEN}Documentation:''${NC}"
-    echo "  See CLAUDE.md and docs/nix.md for more information"
-    echo ""
   '';
 }