Reinstall a damaged Neovim plugin instead of only stashing its changes

Stashing a plugin's mismatched files wasn't enough for LuaSnip: the
interrupted update had also left new files git won't overwrite and a
half-cloned submodule, so lazy.nvim still couldn't check out the new
version, and said nothing. Move such a plugin to
~/.local/state/coredesktop/nvim-plugins/ instead, so Lazy! sync installs
it afresh and any edits to it are kept. A plugin the earlier version of
this step stashed is moved the same way.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/neovim.bats

@@ -7,12 +7,13 @@ load test_helper
 
 setup() {
   common_setup
-  export XDG_DATA_HOME="$HOME/.local/share"
+  export XDG_DATA_HOME="$HOME/.local/share" XDG_STATE_HOME="$HOME/.local/state"
   LAZY="$XDG_DATA_HOME/nvim/lazy"
+  BACKUPS="$XDG_STATE_HOME/coredesktop/nvim-plugins"
   mkdir -p "$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"'
+  stub nvim
 }
 
 # plugin NAME: a plugin checkout with one committed file
@@ -28,28 +29,44 @@ update_neovim() {
   run_update
 }
 
-@test "a plugin with local changes is stashed so lazy.nvim can update it" {
+@test "a plugin whose files don't match its checkout is set aside to be installed again" {
   plugin LuaSnip
   echo changed > "$LAZY/LuaSnip/README.md"
-  echo build output > "$LAZY/LuaSnip/untracked.so"
+  mkdir "$LAZY/LuaSnip/data"
+  echo leftover > "$LAZY/LuaSnip/data/new.md"
 
   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" "$BATS_TEST_TMPDIR/nvim.log"
+  [[ "$output" == *"LuaSnip's files didn't match its version"* ]]
+  [ ! -e "$LAZY/LuaSnip" ]
+  # The old copy, edits and all, is kept
+  copies=("$BACKUPS"/LuaSnip-*)
+  [ "${#copies[@]}" -eq 1 ]
+  [ "$(cat "${copies[0]}/README.md")" = changed ]
+  [ -f "${copies[0]}/data/new.md" ]
+  called nvim --headless "+Lazy! sync" +qa
 }
 
-@test "plugins without local changes are left as they are" {
+@test "a plugin an earlier update only stashed is set aside too" {
+  plugin LuaSnip
+  echo changed > "$LAZY/LuaSnip/README.md"
+  git -C "$LAZY/LuaSnip" stash push -q -m "Stashed by CoreDesktop's update"
+
+  run update_neovim
+  [ "$status" -eq 0 ]
+  [ ! -e "$LAZY/LuaSnip" ]
+  [ -d "$(echo "$BACKUPS"/LuaSnip-*)" ]
+}
+
+@test "plugins that match their checkout are left as they are" {
   plugin lazy.nvim
   echo build output > "$LAZY/lazy.nvim/untracked.so"
+  echo changed > "$LAZY/lazy.nvim/README.md"
+  git -C "$LAZY/lazy.nvim" stash push -q -m "the user's own stash"
 
   run update_neovim
   [ "$status" -eq 0 ]
-  [[ "$output" != *"local changes"* ]]
-  [ -z "$(git -C "$LAZY/lazy.nvim" stash list)" ]
+  [[ "$output" != *"didn't match"* ]]
+  [ -f "$LAZY/lazy.nvim/untracked.so" ]
+  [ ! -e "$BACKUPS" ]
 }