Keep the configured threshold in the pending file

A threshold argument is a one-off override for the notification, so status bars
keep using THRESHOLD from the config.

README.md

@@ -71,7 +71,7 @@ systemctl --user enable --now update-notify.path
 update-notify [threshold]
 ```
 
-`threshold` is the minimum number of updates (repo + AUR) before update counts are shown. It overrides the `THRESHOLD` setting below.
+`threshold` is the minimum number of updates (repo + AUR) before update counts are shown. It overrides the `THRESHOLD` setting below for that run's notification only; the pending file keeps the configured value.
 
 ## Configuration
 
@@ -97,7 +97,7 @@ The content of the last notification is stored in `$XDG_STATE_HOME/update-notify
 Each run also writes the pending updates to `$XDG_STATE_HOME/update-notify/pending`, whether or not the threshold is reached, for status bars such as xmobar to read:
 
 ```
-threshold 30
+threshold <THRESHOLD from the config, not the argument>
 repo <pkg> <newver>
 aur <pkg> <newver>
 kernel <custom-pkg> <stock-ver>

update-notify

@@ -19,10 +19,15 @@ if [[ -r $config_file ]]; then
     # shellcheck source=/dev/null
     source "$config_file"
 fi
+config_threshold=$THRESHOLD  # written to the pending file, so a one-off argument doesn't change status bars
 THRESHOLD=${1:-$THRESHOLD}
 
-[[ $THRESHOLD =~ ^[0-9]+$ ]] || { echo "Threshold must be a number" >&2; exit 1; }
+for t in "$config_threshold" "$THRESHOLD"; do
-THRESHOLD=$((10#$THRESHOLD))  # force base 10, so e.g. "08" isn't read as octal
+    [[ $t =~ ^[0-9]+$ ]] || { echo "Threshold must be a number" >&2; exit 1; }
+done
+# force base 10, so e.g. "08" isn't read as octal
+config_threshold=$((10#$config_threshold))
+THRESHOLD=$((10#$THRESHOLD))
 mkdir -p "$state_dir"
 
 # notify-send from cron/systemd needs the session bus address
@@ -130,7 +135,7 @@ done
 # Pending list for status bars, one "<source> <pkg> <newver>" per line
 # ---------------------------------------------------------------------------
 {
-    printf 'threshold %s\n' "$THRESHOLD"
+    printf 'threshold %s\n' "$config_threshold"
     for item in "${arch_list[@]}"; do
         read -r pkg _ _ new <<< "$item"
         printf 'repo %s %s\n' "$pkg" "$new"