diff --git a/configure.d/40-languages.sh b/configure.d/40-languages.sh
new file mode 100644
index 0000000..797bc47
--- /dev/null
+++ b/configure.d/40-languages.sh
@@ -0,0 +1,62 @@
+#!/bin/bash
+
+# configure reads TITLE and DESCRIPTION
+# shellcheck disable=SC2034
+TITLE="Languages"
+# shellcheck disable=SC2034
+DESCRIPTION="Install more languages with mise, e.g. Ruby on Rails"
+
+# Records that you've chosen, even if you chose nothing, so this isn't "to do"
+LANGUAGES_CONF="$HOME/.config/coredesktop/languages"
+
+# mise installs these gems into each Ruby it installs, so Rails is still there
+# after update moves to a new Ruby
+DEFAULT_GEMS="$HOME/.default-gems"
+
+is_installed() {
+  command -v mise > /dev/null
+}
+
+is_configured() {
+  [ -f "$LANGUAGES_CONF" ]
+}
+
+# Add a gem to ~/.default-gems unless it's there
+add_default_gem() {
+  grep -qsx "$1" "$DEFAULT_GEMS" || echo "$1" >> "$DEFAULT_GEMS"
+}
+
+install_rails() {
+  echo "Installing Ruby and Rails..."
+  add_default_gem bundler || return 1
+  add_default_gem rails || return 1
+  mise use -g ruby@latest || return 1
+  # Ruby may already have been installed before ~/.default-gems listed these
+  mise exec -- gem install --conservative bundler rails || return 1
+  grep -qsx rails "$LANGUAGES_CONF" || echo rails >> "$LANGUAGES_CONF"
+}
+
+run_configure() {
+  local tools tool
+  export MISE_YES=1
+  # From home, so a project's mise.toml in the current directory doesn't count
+  cd "$HOME" || return 1
+
+  echo "Go, Rust, Node.js, Python, Bun and Zig are already installed. mise installs other"
+  echo "languages for you, and the version a project asks for in its mise.toml."
+  mkdir -p "$(dirname "$LANGUAGES_CONF")"
+  touch "$LANGUAGES_CONF" || return 1
+
+  if confirm "Install Ruby on Rails?"; then
+    install_rails || return 1
+  fi
+
+  echo "Anything else? Name tools mise knows (mise registry lists them), with a version,"
+  read -rp "e.g. java@21 deno@latest, or press Enter for none: " tools
+  for tool in $tools; do
+    echo "Installing $tool..."
+    mise use -g "$tool" || return 1
+  done
+
+  echo "update keeps them up to date. To remove one later: mise unuse -g <tool>"
+}
diff --git a/install-mise-ruby-rails.sh b/install-mise-ruby-rails.sh
deleted file mode 100755
index 3a0fafe..0000000
--- a/install-mise-ruby-rails.sh
+++ /dev/null
@@ -1,54 +0,0 @@
-#!/bin/bash
-
-# set -e
-
-#====================================================================================
-# Install Mise
-#====================================================================================
-
-# Check if Mise is already installed
-if ! command -v mise &> /dev/null; then
-  echo "Installing Mises"
-  curl https://mise.run/bash | sh
-else
-  echo "Mises is installed"
-fi
-
-eval "$($HOME/.local/bin/mise activate bash)"
-
-source ~/.bashrc
-
-#====================================================================================
-# Install Ruby
-#====================================================================================
-
-# Check if Ruby is already installed
-if ! command -v ruby &> /dev/null; then
-  echo "Installing Ruby"
-  mise install ruby@latest
-  mise use -g ruby@latest
-
-# Explicitly add shims to PATH
-  export PATH="$HOME/.local/share/mise/shims:$PATH"
-
-# Force reshim
-  $HOME/.local/bin/mise reshim
-
-  source "$HOME/.bashrc"
-
-  gem install bundler
-else
-  echo "Ruby is installed"
-fi
-
-#====================================================================================
-# Install Rails
-#====================================================================================
-
-# Check if Rails is already installed
-if ! command -v rails &> /dev/null; then
-  echo "Installing Rails"
-  gem install rails
-else
-  echo "Rails is installed"
-fi
diff --git a/migrations/1793453501.sh b/migrations/1793453501.sh
new file mode 100644
index 0000000..08bcd4a
--- /dev/null
+++ b/migrations/1793453501.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+
+# mise now comes from pacman, and shell/bashrc activates it, so remove the copy
+# mise.run installed in ~/.local/bin and the line it added to ~/.bashrc. Ruby and
+# Rails are no longer installed for everyone, only with configure languages:
+# machines that have them keep them, and update keeps Rails on new Rubies.
+LANGUAGES_CONF="$HOME/.config/coredesktop/languages"
+DEFAULT_GEMS="$HOME/.default-gems"
+
+# 10-pacman.sh installs mise from packages.conf before migrations run
+[ -x /usr/bin/mise ] || { echo "mise isn't installed from pacman yet."; exit 1; }
+
+if [ -f ~/.bashrc ] && grep -qE '\.local/bin/mise activate' ~/.bashrc; then
+  tmp="$(mktemp ~/.bashrc.XXXXXX)" || exit 1
+  # grep -v exits 1 when that line was all there was, which is fine
+  grep -vE '\.local/bin/mise activate' ~/.bashrc > "$tmp"
+  (( $? <= 1 )) && cat "$tmp" > ~/.bashrc
+  status=$?
+  rm -f "$tmp"
+  [ $status -eq 0 ] || exit 1
+fi
+rm -f ~/.local/bin/mise
+
+# Ruby that CoreDesktop installed: count it as chosen with configure languages.
+# From home, so a project's mise.toml in the current directory doesn't count.
+cd "$HOME" || exit 1
+if /usr/bin/mise ls --global --quiet 2> /dev/null | grep -q '^ruby '; then
+  mkdir -p "$(dirname "$LANGUAGES_CONF")" || exit 1
+  grep -qsx rails "$LANGUAGES_CONF" || echo rails >> "$LANGUAGES_CONF"
+  for gem in bundler rails; do
+    grep -qsx "$gem" "$DEFAULT_GEMS" || echo "$gem" >> "$DEFAULT_GEMS"
+  done
+  # update used to move to a new Ruby without Rails
+  echo "Making sure Rails is installed..."
+  MISE_YES=1 /usr/bin/mise exec -- gem install --conservative bundler rails || exit 1
+fi
+exit 0
diff --git a/updates.d/40-ruby.sh b/updates.d/40-mise.sh
similarity index 100%
rename from updates.d/40-ruby.sh
rename to updates.d/40-mise.sh