Keep auto paused instances paused

Every RCON command makes an auto paused Factorio server run one tick, so
subspace_storage's 1 s inventory update and 5 s ping, plus a
statistics_exporter gather on every Prometheus scrape, kept a server with
nobody online running at about 1.3 ticks per second.

The instance now records the auto_pause server setting it was started
with and exposes autoPaused, true while that setting is on and no players
are online, along with an autoPauseChanged hook. subspace_storage skips
its timers while paused and sends a ping and inventory as soon as a player
joins. statistics_exporter gathers once after the game pauses and keeps
serving those values until it resumes.

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

docs/configuration.md

@@ -644,6 +644,8 @@ The settings in `data/server-settings.example.json` of the Factorio installation
 
 Changes to the following properties will be applied live if the instance is running while it is changed: `afk_autokick_interval`, `allow_commands`, `autosave_interval`, `autosave_only_on_server`, `description`, `ignore_player_limit_for_returning_players`, `max_players`, `max_upload_slots`, `max_upload_in_kilobytes_per_second`, `name`, `only_admins_can_pause_the_game`, `game_password`, `require_user_verification`, `tags`, `visibility`.
 
+With `auto_pause` on, the plugins included with Clusterio stop their periodic commands while no players are online, so the game stays paused.
+
 Defaults to a set of common settings filled in when the instance is created, such as `"tags": ["clusterio"]`, `"auto_pause": false` and a `name` and `description` based on the cluster and instance names.
 
 

docs/writing-plugins.md

@@ -505,6 +505,25 @@ Data out from Factorio does not have the same limits as data into Factorio, RCON
 For `send_json` it's possible that payloads greater than 4kB are received after payloads that were sent at a later point in time.
 For RCON, commands longer than 50 characters may end up being executed after shorter commands sent after it.
 
+### Auto pause
+
+Each RCON command makes a paused game run one tick, so commands sent on a timer keep a server with `auto_pause` on running while nobody is online.
+`instance.autoPaused` is true while the instance was started with `auto_pause` on and no players are online, and the `autoPauseChanged` hook is invoked with the new value when it changes.
+Skip periodic commands while it is true:
+
+```js
+instance.hooks.start.attach(plugin.name, async () => {
+    timer = setInterval(() => {
+        if (!instance.autoPaused) {
+            instance.sendRcon("/sc my_plugin.update()").catch(handleError);
+        }
+    }, 1000);
+});
+```
+
+Commands sent in response to events from elsewhere in the cluster are fine, they cost one tick each.
+A game paused with `game.tick_paused` does not run ticks for commands.
+
 ### Communicating over UDP
 
 Instances can optionally exchange UDP packets with the Factorio server for low latency fire-and-forget communication, using the `--enable-lua-udp` option of Factorio.