feat(pocket-base): add mob spawning toggle

design/log.md

@@ -91,3 +91,10 @@ description: Chronological record of material decisions affecting the Spigot Bas
 - Used the live size-tier radius so expansion and relocation immediately update the visibility threshold.
 - Added exact-boundary and controller integration coverage.
 - Verified the change with `./gradlew clean check jar`.
+
+## 2026-08-24 — Pocket Base mob-spawning control
+
+- Disabled natural hostile and passive mob spawning by default in new and existing Pocket Bases without a saved preference.
+- Added the persisted owner setting `/basesettings pocket mobs enable|disable`, contextual autocomplete, and status reporting.
+- Reapplied saved spawn flags when Pocket Base worlds load and restored the prior world setting when persistence fails.
+- Verified the feature with `./gradlew clean check jar`.

design/user-stories/index.md

@@ -23,3 +23,4 @@ description: Catalog of user stories for the Spigot Base plugin.
 15. [US-015: Unlock a Pocket Base](us-015-unlock-a-pocket-base.md)
 16. [US-016: Build and use Pocket Base portals](us-016-build-and-use-pocket-base-portals.md)
 17. [US-017: Expand a Pocket Base](us-017-expand-a-pocket-base.md)
+18. [US-018: Control Pocket Base mob spawning](us-018-control-pocket-base-mob-spawning.md)

design/user-stories/us-018-control-pocket-base-mob-spawning.md

@@ -0,0 +1,28 @@
+---
+type: User Story
+title: "US-018: Control Pocket Base mob spawning"
+description: Let Pocket Base owners control natural mob spawning in their private world, with spawning disabled by default.
+status: done
+---
+
+# US-018: Control Pocket Base mob spawning
+
+As a **Pocket Base owner**, I want to enable or disable natural mob spawning in my Pocket Base so that I can choose whether the private world supports normal mob activity.
+
+## Acceptance criteria
+
+- [x] Natural mob spawning is disabled by default in every new Pocket Base and in existing Pocket Bases that have no saved preference.
+- [x] A Pocket Base owner can use `/basesettings pocket mobs enable|disable` to control natural mob spawning in their own Pocket Base.
+- [x] The setting controls both hostile and passive natural spawning only in the owner's Pocket Base.
+- [x] The command is unavailable until Pocket Base I is unlocked.
+- [x] The command and its modes are offered through contextual autocomplete.
+- [x] `/basesettings status` displays the current Pocket Base mob-spawning setting.
+- [x] The preference persists across restarts and is reapplied when the Pocket Base world loads.
+- [x] Disabling natural spawning does not remove existing mobs or prevent explicitly spawned or summoned mobs.
+- [x] Persistence or world-application failures produce a clear failure message without reporting a successful change.
+
+## Related
+
+- [US-015: Unlock a Pocket Base](us-015-unlock-a-pocket-base.md)
+- [US-016: Build and use Pocket Base portals](us-016-build-and-use-pocket-base-portals.md)
+- [US-017: Expand a Pocket Base](us-017-expand-a-pocket-base.md)