diff --git a/install-flatpaks.sh b/install-flatpaks.sh
index 8c6f68e..36b452b 100755
--- a/install-flatpaks.sh
+++ b/install-flatpaks.sh
@@ -9,7 +9,7 @@ FLATPAKS=(
   "com.logseq.Logseq"
   "org.gnome.gitlab.somas.Apostrophe"
   "org.signal.Signal"
-  "org.mozilla.Thunderbird"
+  "org.mozilla.thunderbird_esr"
   "dev.deedles.Trayscale"
   "com.vivaldi.Vivaldi"
   "org.telegram.desktop"
diff --git a/migrations/1794160046.sh b/migrations/1794160046.sh
new file mode 100644
index 0000000..1e09221
--- /dev/null
+++ b/migrations/1794160046.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# Flathub retired org.mozilla.Thunderbird in favor of org.mozilla.thunderbird_esr,
+# and flatpak update moves existing installs over itself. A skip-packages entry
+# for the old ID would no longer keep Thunderbird from being installed, so
+# carry it over to the new one.
+SKIP_PACKAGES="$HOME/.config/coredesktop/skip-packages"
+[ -f "$SKIP_PACKAGES" ] || exit 0
+grep -qE '^org\.mozilla\.Thunderbird([[:space:]]|$)' "$SKIP_PACKAGES" || exit 0
+grep -qE '^org\.mozilla\.thunderbird_esr([[:space:]]|$)' "$SKIP_PACKAGES" && exit 0
+# Start a new line if the file doesn't end with one
+[ -n "$(tail -c 1 "$SKIP_PACKAGES")" ] && echo >> "$SKIP_PACKAGES"
+echo "org.mozilla.thunderbird_esr" >> "$SKIP_PACKAGES"
diff --git a/tests/migrations.bats b/tests/migrations.bats
new file mode 100644
index 0000000..ed5557e
--- /dev/null
+++ b/tests/migrations.bats
@@ -0,0 +1,34 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+# Migrations that change files in the user's home
+
+SKIP="$BATS_TEST_TMPDIR/home/.config/coredesktop/skip-packages"
+THUNDERBIRD="$REPO/migrations/1794160046.sh"
+
+skip_list() {
+  mkdir -p "$(dirname "$SKIP")"
+  printf "$1" > "$SKIP"
+}
+
+@test "skipping the old Thunderbird ID carries over to the new one" {
+  skip_list 'foo\norg.mozilla.Thunderbird  # no mail'
+  run bash "$THUNDERBIRD"
+  [ "$status" -eq 0 ]
+  [ "$(cat "$SKIP")" = "$(printf 'foo\norg.mozilla.Thunderbird  # no mail\norg.mozilla.thunderbird_esr')" ]
+}
+
+@test "the Thunderbird migration leaves other skip lists alone" {
+  for list in 'org.mozilla.ThunderbirdX\n' 'org.mozilla.Thunderbird\norg.mozilla.thunderbird_esr\n'; do
+    skip_list "$list"
+    before="$(cat "$SKIP")"
+    run bash "$THUNDERBIRD"
+    [ "$status" -eq 0 ]
+    [ "$(cat "$SKIP")" = "$before" ]
+  done
+  rm -f "$SKIP"
+  run bash "$THUNDERBIRD"
+  [ "$status" -eq 0 ]
+  [ ! -e "$SKIP" ]
+}
diff --git a/tests/neovim.bats b/tests/neovim.bats
new file mode 100644
index 0000000..347cb3c
--- /dev/null
+++ b/tests/neovim.bats
@@ -0,0 +1,55 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+# updates.d/46-neovim.sh, with real git repositories standing in for the
+# plugins lazy.nvim cloned
+
+setup() {
+  common_setup
+  export XDG_DATA_HOME="$HOME/.local/share"
+  LAZY="$XDG_DATA_HOME/nvim/lazy"
+  mkdir -p "$LAZY"
+  export GIT_AUTHOR_NAME=test GIT_AUTHOR_EMAIL=test@example.com
+  export GIT_COMMITTER_NAME=test GIT_COMMITTER_EMAIL=test@example.com
+  stub nvim 'echo "nvim ran" >> "$BATS_TEST_TMPDIR/nvim.log"'
+}
+
+# plugin NAME: a plugin checkout with one committed file
+plugin() {
+  git init -q "$LAZY/$1"
+  echo original > "$LAZY/$1/README.md"
+  git -C "$LAZY/$1" add README.md
+  git -C "$LAZY/$1" commit -q -m initial
+}
+
+update_neovim() {
+  source "$REPO/updates.d/46-neovim.sh"
+  run_update
+}
+
+@test "a plugin with local changes is stashed so lazy.nvim can update it" {
+  plugin LuaSnip
+  echo changed > "$LAZY/LuaSnip/README.md"
+  echo build output > "$LAZY/LuaSnip/untracked.so"
+
+  run update_neovim
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"LuaSnip had local changes"* ]]
+  [ -z "$(git -C "$LAZY/LuaSnip" ls-files -d -m)" ]
+  [ "$(cat "$LAZY/LuaSnip/README.md")" = original ]
+  # The changes can be got back, and untracked build output is left alone
+  git -C "$LAZY/LuaSnip" stash list | grep -q "Stashed by CoreDesktop's update"
+  [ -f "$LAZY/LuaSnip/untracked.so" ]
+  grep -q "nvim ran" "$BATS_TEST_TMPDIR/nvim.log"
+}
+
+@test "plugins without local changes are left as they are" {
+  plugin lazy.nvim
+  echo build output > "$LAZY/lazy.nvim/untracked.so"
+
+  run update_neovim
+  [ "$status" -eq 0 ]
+  [[ "$output" != *"local changes"* ]]
+  [ -z "$(git -C "$LAZY/lazy.nvim" stash list)" ]
+}
diff --git a/updates.d/46-neovim.sh b/updates.d/46-neovim.sh
index 1081714..d59966d 100755
--- a/updates.d/46-neovim.sh
+++ b/updates.d/46-neovim.sh
@@ -1,11 +1,29 @@
 #!/bin/bash
 
 # Only the plugins are updated; the kickstart.nvim config itself is the user's to edit.
+LAZY_DIR="${XDG_DATA_HOME:-$HOME/.local/share}/nvim/lazy"
+
 is_installed() {
-  command -v nvim &>/dev/null && [ -d "${XDG_DATA_HOME:-$HOME/.local/share}/nvim/lazy/lazy.nvim" ]
+  command -v nvim &>/dev/null && [ -d "$LAZY_DIR/lazy.nvim" ]
+}
+
+# lazy.nvim won't update a plugin whose tracked files differ from its checkout
+# (it checks with `git ls-files -d -m`), which an interrupted update can leave
+# behind. Stash those changes, so the plugin updates and they can still be
+# recovered with `git stash pop` in its folder, and put its submodules back.
+restore_plugins() {
+  local dir
+  for dir in "$LAZY_DIR"/*/; do
+    [ -d "$dir/.git" ] || continue
+    [ -n "$(git -C "$dir" ls-files -d -m 2> /dev/null)" ] || continue
+    echo "  $(basename "$dir") had local changes; stashing them so it can update."
+    git -C "$dir" stash push -q -m "Stashed by CoreDesktop's update" \
+      && git -C "$dir" submodule update -q --init --recursive --force
+  done
 }
 
 run_update() {
   echo "Updating Neovim plugins..."
+  restore_plugins
   nvim --headless "+Lazy! sync" +qa
 }