feat(border): add base boundary particles

design/log.md

@@ -69,3 +69,10 @@ description: Chronological record of material decisions affecting the Spigot Bas
 - Removed the unsafe unconfirmed base reset path; complete resets now require `reset <player> all confirm`.
 - Tightened argument validation and replaced implementation-specific enum errors with player-facing usage guidance.
 - Verified the administrative revision with `./gradlew clean check jar`.
+
+## 2026-08-10 — Base border visualization
+
+- Added persisted, owner-only base border particles controlled by `/basesettings border enable|disable` with contextual autocomplete.
+- Rendered a bounded nearby arc at the player's current height using the current base radius while respecting world and vertical bounds.
+- Added border preference reporting to player and administrative status output and safe defaults for existing state files.
+- Verified the feature with `./gradlew clean check jar`.

design/user-stories/index.md

@@ -18,3 +18,4 @@ description: Catalog of user stories for the Spigot Base plugin.
 10. [US-010: Administer player progression](us-010-administer-player-progression.md)
 11. [US-011: Configure and persist progression](us-011-configure-and-persist-progression.md)
 12. [US-012: Build and release the plugin](us-012-build-and-release-plugin.md)
+13. [US-013: Visualize the base border](us-013-visualize-base-border.md)

design/user-stories/us-013-visualize-base-border.md

@@ -0,0 +1,31 @@
+---
+type: User Story
+title: "US-013: Visualize the base border"
+description: Let players display a bounded, owner-only particle arc along the current edge of their established base.
+status: done
+---
+
+# US-013: Visualize the base border
+
+As a **player with Base I**, I want to display a particle effect at my base border so that I can understand where base benefits begin and end while building.
+
+## Acceptance criteria
+
+- [x] Border visualization requires Base I and an established base.
+- [x] `/basesettings border enable` enables visualization idempotently, and `/basesettings border disable` disables it idempotently.
+- [x] `border`, `enable`, and `disable` are offered through contextual autocomplete.
+- [x] Border visualization is disabled by default and the preference persists across reconnects and restarts.
+- [x] Older state files without the preference load it as disabled.
+- [x] `/basesettings status` and `/baseadmin status` display the border preference.
+- [x] Particles are visible only to the base owner.
+- [x] Particles trace the current circular horizontal boundary at the player's current Y-level and follow base expansion or relocation immediately.
+- [x] Particles render only while the player is in the base world, within the base's vertical range, and reasonably close to the boundary.
+- [x] Particle generation is bounded to avoid excessive server and client load.
+- [x] A complete administrative reset disables border visualization.
+
+## Related
+
+- [US-001: Unlock and establish Base I](us-001-unlock-and-establish-base.md)
+- [US-003: Expand the base](us-003-expand-the-base.md)
+- [US-009: View progression and unlock notifications](us-009-view-progression-and-notifications.md)
+- [US-010: Administer player progression](us-010-administer-player-progression.md)