version: show a spinner while it checks for updates

Checking for newer versions goes to the network and can take several
seconds with nothing on screen. Show "Checking for updates..." with a
spinner on the terminal until every check is done, then print the
results all at once. The spinner goes to stderr and only to a terminal.

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

tests/version.bats

@@ -133,3 +133,18 @@ sibling_repo() {
   [[ "$output" == *"tools is at v1.1.0."* ]]
   [ "$(cat "$HOME/updated")" = "$HOME/.local/share/siblings/tools" ]
 }
+
+@test "version shows a spinner on a terminal while it checks, and clears it" {
+  run script -qec "bash '$CD/version'" /dev/null < /dev/null
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"Checking for updates..."* ]]
+  # Cleared, and the cursor shown again, before the results are printed
+  [[ "$output" == *$'\r\e[K\e[?25hCoreDesktop  2026.10.31'* ]]
+}
+
+@test "version shows no spinner when its output isn't a terminal" {
+  run bash "$CD/version"
+  [ "$status" -eq 0 ]
+  [[ "$output" != *"Checking"* ]]
+  [[ "$output" != *$'\e[?25l'* ]]
+}

version

@@ -43,6 +43,35 @@ if [ "$1" = "--check" ]; then
   exit
 fi
 
+# Checking for newer versions goes to the network and can take several
+# seconds, so show a spinner on the terminal until the results are ready. It
+# goes to stderr and only to a terminal, so output that's piped stays clean.
+spinner_pid=""
+start_spinner() {
+  [ -t 2 ] || return 0
+  (
+    frames=('⠋' '⠙' '⠹' '⠸' '⠼' '⠴' '⠦' '⠧' '⠇' '⠏')
+    i=0
+    printf '\e[?25l' >&2
+    while :; do
+      printf '\r%s Checking for updates...' "${frames[i++ % ${#frames[@]}]}" >&2
+      sleep 0.1
+    done
+  ) &
+  spinner_pid=$!
+}
+stop_spinner() {
+  [ -n "$spinner_pid" ] || return 0
+  kill "$spinner_pid" 2> /dev/null
+  wait "$spinner_pid" 2> /dev/null
+  spinner_pid=""
+  printf '\r\e[K\e[?25h' >&2
+}
+trap stop_spinner EXIT
+trap 'stop_spinner; exit 130' INT TERM
+
+start_spinner
+
 version="$(describe HEAD)"
 
 # Local edits to the checkout mean this isn't exactly the version above
@@ -123,13 +152,19 @@ else
   last_update="never"
 fi
 
+# Sibling projects, as "name<TAB>installed<TAB>available" lines (see sibling)
+siblings="$(bash "$COREDESKTOP/sibling" check --porcelain 2> /dev/null)"
+
+# Hours since the package mirror last synced with Arch, empty if unknown
+age="$(mirror_age_hours)"
+
+stop_spinner
+
 echo "CoreDesktop  $version"
 echo "Kernel       $kernel"
 [ -n "$driver" ] && echo "Video driver $driver"
 echo "Last update  $last_update"
 
-# Sibling projects, as "name<TAB>installed<TAB>available" lines (see sibling)
-siblings="$(bash "$COREDESKTOP/sibling" check --porcelain 2> /dev/null)"
 newer_siblings=()
 if [ -n "$siblings" ]; then
   echo
@@ -152,7 +187,7 @@ if [ -n "$siblings" ]; then
 fi
 
 # Packages newer than the mirror's last sync aren't shown above, or installed
-if age="$(mirror_age_hours)" && (( age >= MIRROR_STALE_HOURS )); then
+if [ -n "$age" ] && (( age >= MIRROR_STALE_HOURS )); then
   if (( age >= 48 )); then ago="$(( age / 24 )) days"; else ago="$age hours"; fi
   echo
   echo -e "\e[33mYour package mirror ($(first_mirror)) last synced with Arch $ago ago, so"