Add fleet and per-host concurrency controls

docs/provisioning.md

@@ -196,3 +196,19 @@ detail endpoints. No history or IDs are renamed or discarded.
 Start and Stop use durable `instance.start` and `instance.stop` host-agent
 operations. Rebuild uses `instance.rebuild` and replaces the instance files.
 See [native host management](native-hosts.md) for command delivery and recovery.
+
+### Additional concurrency limits
+
+Administration → Settings separates Concurrency and Retention, with independent
+save actions. Existing fleet restart, startup and destruction limits continue to
+apply. Additional per-host restart, startup and destruction limits, a combined
+lifecycle limit, a rebuild limit, and a limit on hosts preparing game files default
+to 0 (no additional cap), preserving existing throughput on upgrade.
+
+Lifecycle work counts once toward the combined limit, including launch preparation
+and unresolved delivered commands. Rebuilds include drain migrations and retain
+capacity between source removal and destination creation. Per-host recovery slots
+remain occupied until health verification. Lowering limits does not cancel work.
+Game-file preparation is limited when commands are delivered; downloads and imports
+share the cap, including manual requests. Replayed or interrupted commands retain
+the same host slot. Runtime image pulls and per-host file transfer counts are unchanged.