fix(teleport): require same dimension for visits

README.md

@@ -32,9 +32,14 @@ The plugin JAR is written to `build/libs/`.
 /basesettings navigation <enable|disable>
 /basesettings flight <enable|disable>
 /basesettings border <enable|disable>
+/basesettings spawnable <enable|disable>
 /basesettings bossbar <enable|disable>
 ```
 
+Navigation particles appear only in the base's world and when the player is more than 25 blocks beyond the current base border.
+
+After 250 Survival-mode block placements anywhere by default, the spawnable overlay can mark nearby dark hostile-mob spawning surfaces inside the player's base with owner-only red particles. The threshold is configurable.
+
 `/base` has a stationary warm-up. Looking around is allowed, while movement between blocks, damage, teleportation, world changes, death, logout, and conflicting teleport commands cancel it without consuming the cooldown.
 
 ## Administration
@@ -44,8 +49,10 @@ The `spigotbase.admin` permission is granted to server operators by default. `/h
 ```text
 /baseadmin status <player>
 /baseadmin setlevel <player> <base|size|flight|warmup|cooldown> <level>
-/baseadmin setprogress <player> <grass_dirt|stone|deepslate|obsidian|placements|base_breaks> <amount>
+/baseadmin setprogress <player> <grass_dirt|stone|deepslate|obsidian|placements|total_placements|base_breaks> <amount>
+/baseadmin setsetting <player> spawnable <enable|disable>
 /baseadmin config <numeric-key> <value>
+# e.g. /baseadmin config spawnable-overlay-unlock-placements 250
 /baseadmin clearcooldown <player> [personal|visitor|all]
 /baseadmin reset <player> <size|flight|warmup|cooldown>
 /baseadmin reset <player> all confirm

design/log.md

@@ -76,3 +76,18 @@ description: Chronological record of material decisions affecting the Spigot Bas
 - 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`.
+
+## 2026-08-10 — Spawnable block overlay
+
+- Added persistent progression for Survival-mode block placements anywhere, with existing in-base placement counts used as a safe migration minimum.
+- Added `/basesettings spawnable enable|disable` after a configurable 250-placement unlock and reported its progress and preference in player and admin status output.
+- Added admin controls for total placement progress, the unlock threshold, and each unlocked player's overlay preference.
+- Added owner-only red particles for nearby dark spawning surfaces inside base bounds, using bounded incremental scanning and rendering budgets.
+- Verified the feature with `./gradlew clean check jar`.
+
+## 2026-08-10 — Navigation visibility buffer
+
+- Limited enabled base navigation particles to the base's world and positions more than 25 horizontal blocks beyond the current base border.
+- 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`.

design/user-stories/index.md

@@ -19,3 +19,4 @@ description: Catalog of user stories for the Spigot Base plugin.
 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)
+14. [US-014: Highlight spawnable blocks](us-014-highlight-spawnable-blocks.md)

design/user-stories/us-002-unlock-base-navigation.md

@@ -14,7 +14,9 @@ As a **player with Base I**, I want visual guidance toward my base so that I can
 - [x] Base II requires Base I and an established base.
 - [x] Base II unlocks at a configurable cumulative grass-or-dirt threshold that defaults to 500 blocks, 250 more than Base I.
 - [x] Base II provides particle-based navigation and does not grant or require a physical compass item.
-- [x] While enabled and in the base's world, particles are drawn along the ground to indicate the direction toward the base.
+- [x] While enabled and in the base's world, particles are drawn along the ground only when the player is horizontally more than 25 blocks beyond the current base border.
+- [x] No navigation particles appear inside the base, exactly 25 blocks beyond its border, or anywhere within that buffer.
+- [x] Expansion and relocation update the navigation visibility threshold immediately.
 - [x] Particle generation is bounded to avoid excessive server or client load.
 - [x] A player in another world receives a clear message instead of a misleading particle direction.
 - [x] `/basesettings navigation enable` enables guidance idempotently after Base II is unlocked, and `/basesettings navigation disable` disables it idempotently.

design/user-stories/us-004-unlock-and-control-base-flight.md

@@ -21,7 +21,7 @@ As a **player with Base I**, I want to unlock controlled flight around my base s
 - [x] Flight II expands the vertical range to 100 blocks below and above base Y by default.
 - [x] Flight III expands the vertical range to the world's minimum and maximum build heights.
 - [x] A configurable five-block horizontal warning buffer extends beyond the current base radius.
-- [x] Plugin-granted flight remains active in the warning buffer and displays prominent on-screen notice that the player is leaving the base.
+- [x] Plugin-granted flight remains active in the warning buffer, and a prominent on-screen notice that the player is leaving the base appears only while the player is actively flying.
 - [x] Passing beyond the warning buffer removes only flight granted by this plugin.
 - [x] Flight is not granted outside the unlocked vertical range.
 - [x] `/basesettings flight enable` enables unlocked flight idempotently, and `/basesettings flight disable` disables it idempotently.

design/user-stories/us-008-unlock-visitor-access.md

@@ -21,7 +21,8 @@ As a **player with Base III**, I want to open my base to visitors so that other
 - [x] `/gotobase <owner>` autocompletes bases that the requesting player is currently eligible to visit.
 - [x] `/visit <owner>` aliases `/gotobase <owner>` with identical autocomplete, including eligible bases whose owners are offline.
 - [x] Enabled bases remain visitable while their owners are offline.
-- [x] A visitor teleport uses the destination owner's current warm-up tier.
+- [x] `/visit` and `/gotobase` require the visitor to be in the destination base's recorded world; cross-dimension requests are rejected before warm-up with a clear message and without consuming cooldown.
+- [x] A visitor teleport uses the destination owner's current warm-up tier, but always requires at least a one-second stationary warm-up; `/visit` and `/gotobase` never teleport instantly.
 - [x] Looking around is permitted, while movement between block coordinates, damage, teleportation, world change, death, logout, or a conflicting teleport cancels the visitor warm-up.
 - [x] Cancellation or destination failure does not consume a visitor cooldown.
 - [x] A safe destination is resolved at or near the owner's recorded base center.

design/user-stories/us-014-highlight-spawnable-blocks.md

@@ -0,0 +1,34 @@
+---
+type: User Story
+title: "US-014: Highlight spawnable blocks"
+description: Unlock an owner-only red particle overlay for nearby hostile-mob spawnable blocks after 250 placements anywhere.
+status: done
+---
+
+# US-014: Highlight spawnable blocks
+
+As a **player with an established base**, I want to highlight nearby blocks where hostile mobs can spawn so that I can find lighting gaps in my base.
+
+## Acceptance criteria
+
+- [x] Every block placed in Survival mode anywhere contributes to a persistent total-placement counter.
+- [x] The overlay unlocks permanently at a configurable 250 total placements by default.
+- [x] Existing players begin with at least their persisted in-base placement count because those placements are known to qualify.
+- [x] `/basesettings spawnable enable` enables the unlocked overlay idempotently, and `/basesettings spawnable disable` disables it idempotently.
+- [x] `spawnable`, `enable`, and `disable` are offered through contextual autocomplete.
+- [x] Enabling requires both the placement unlock and an established base; the persisted preference defaults to disabled.
+- [x] `/basesettings status` and `/baseadmin status` display placement progress, unlock state, and preference.
+- [x] Administrators can change a player's total-placement counter through `/baseadmin setprogress`.
+- [x] Administrators can persistently change the required placement threshold through `/baseadmin config spawnable-overlay-unlock-placements`.
+- [x] Administrators can enable or disable an unlocked player's overlay through `/baseadmin setsetting <player> spawnable <enable|disable>`.
+- [x] Owner-only red particles mark nearby candidate hostile-mob spawning surfaces inside the current base bounds.
+- [x] Candidate surfaces have block light zero, a solid spawning surface, and two passable blocks above them.
+- [x] Scanning is bounded to 16 horizontal blocks, eight vertical blocks, and a fixed per-update work and particle budget.
+- [x] A complete administrative reset clears total-placement progress and disables the overlay.
+
+## Related
+
+- [US-001: Unlock and establish Base I](us-001-unlock-and-establish-base.md)
+- [US-009: View progression and notifications](us-009-view-progression-and-notifications.md)
+- [US-010: Administer player progression](us-010-administer-player-progression.md)
+- [US-011: Configure and persist progression](us-011-configure-and-persist-progression.md)

src/main/java/games/dmg/spigotbase/AdminProgressionService.java

@@ -92,6 +92,7 @@ public final class AdminProgressionService {
         long deepslate = player.deepslateBroken();
         long obsidian = player.obsidianBroken();
         long placements = player.blocksPlacedInBase();
+        long totalPlacements = player.totalBlocksPlaced();
         long baseBreaks = player.blocksBrokenInBase();
         switch (counter) {
             case GRASS_DIRT -> grassDirt = amount;
@@ -99,6 +100,7 @@ public final class AdminProgressionService {
             case DEEPSLATE -> deepslate = amount;
             case OBSIDIAN -> obsidian = amount;
             case PLACEMENTS -> placements = amount;
+            case TOTAL_PLACEMENTS -> totalPlacements = amount;
             case BASE_BREAKS -> baseBreaks = amount;
         }
         PluginSettings configured = settings.current();
@@ -147,7 +149,11 @@ public final class AdminProgressionService {
         }
         PlayerState updated = player.withProgressCounters(
             grassDirt, stone, deepslate, obsidian, placements, baseBreaks
-        );
+        ).withTotalBlocksPlaced(totalPlacements);
+        if (totalPlacements < configured.spawnableOverlayUnlockPlacements()
+                && updated.spawnableOverlayEnabled()) {
+            updated = updated.withSpawnableOverlayEnabled(false);
+        }
         return updated.withAdministrativeLevels(
             base,
             size,

src/main/java/games/dmg/spigotbase/BaseAdminCommand.java

@@ -16,14 +16,17 @@ import org.bukkit.plugin.java.JavaPlugin;
 
 final class BaseAdminCommand implements CommandExecutor, TabCompleter {
     private static final List<String> SUBCOMMANDS = List.of(
-        "status", "setlevel", "setprogress", "clearcooldown", "reset", "config"
+        "status", "setlevel", "setprogress", "setsetting", "clearcooldown", "reset", "config"
     );
     private static final List<String> PATHS = List.of(
         "base", "size", "flight", "warmup", "cooldown"
     );
     private static final List<String> COUNTERS = List.of(
-        "grass_dirt", "stone", "deepslate", "obsidian", "placements", "base_breaks"
+        "grass_dirt", "stone", "deepslate", "obsidian", "placements", "total_placements",
+        "base_breaks"
     );
+    private static final List<String> SETTINGS = List.of("spawnable");
+    private static final List<String> ENABLE_MODES = List.of("enable", "disable");
     private static final List<String> COOLDOWN_TYPES = List.of("personal", "visitor", "all");
     private static final List<String> RESET_PATHS = List.of(
         "size", "flight", "warmup", "cooldown", "all"
@@ -69,6 +72,7 @@ final class BaseAdminCommand implements CommandExecutor, TabCompleter {
             case "status" -> showProgress(sender, target.orElseThrow(), arguments);
             case "setlevel" -> setLevel(sender, target.orElseThrow(), arguments);
             case "setprogress" -> setProgress(sender, target.orElseThrow(), arguments);
+            case "setsetting" -> setSetting(sender, target.orElseThrow(), arguments);
             case "clearcooldown" -> clearCooldown(sender, target.orElseThrow(), arguments);
             case "reset" -> reset(sender, target.orElseThrow(), arguments);
             default -> {
@@ -94,11 +98,17 @@ final class BaseAdminCommand implements CommandExecutor, TabCompleter {
         sender.sendMessage(ChatColor.GRAY + "Grass/dirt=" + player.grassAndDirtBroken()
             + " stone=" + player.stoneBroken() + " deepslate=" + player.deepslateBroken()
             + " obsidian=" + player.obsidianBroken());
+        int spawnableThreshold = settingsProvider.current()
+            .spawnableOverlayUnlockPlacements();
         sender.sendMessage(ChatColor.GRAY + "In-base placements=" + player.blocksPlacedInBase()
+            + " total placements=" + player.totalBlocksPlaced()
             + " breaks=" + player.blocksBrokenInBase());
+        sender.sendMessage(ChatColor.GRAY + "Spawnable overlay="
+            + (player.totalBlocksPlaced() >= spawnableThreshold ? "unlocked" : "locked")
+            + " (" + player.totalBlocksPlaced() + "/" + spawnableThreshold + ")");
         sender.sendMessage(ChatColor.GRAY + "Toggles: navigation=" + player.navigationEnabled()
             + " flight=" + player.flightEnabled() + " border=" + player.borderEnabled()
-            + " bossbar=" + player.bossBarEnabled() + " visitors=" + player.visitorsEnabled());
+            + " spawnable=" + player.spawnableOverlayEnabled() + " bossbar=" + player.bossBarEnabled() + " visitors=" + player.visitorsEnabled());
         sender.sendMessage(ChatColor.GRAY + "Base: " + player.base()
             .map(base -> base.worldName() + " " + base.x() + "," + base.y() + "," + base.z())
             .orElse("not set"));
@@ -160,7 +170,8 @@ final class BaseAdminCommand implements CommandExecutor, TabCompleter {
         } catch (IllegalArgumentException exception) {
             sender.sendMessage(ChatColor.RED
                 + "Usage: /baseadmin setprogress <player> "
-                + "<grass_dirt|stone|deepslate|obsidian|placements|base_breaks> <amount>");
+                + "<grass_dirt|stone|deepslate|obsidian|placements|total_placements|base_breaks> "
+                + "<amount>");
             return true;
         }
         try {
@@ -181,6 +192,39 @@ final class BaseAdminCommand implements CommandExecutor, TabCompleter {
         return true;
     }
 
+    private boolean setSetting(
+        CommandSender sender,
+        PlayerState target,
+        String[] arguments
+    ) {
+        if (arguments.length != 4
+                || !arguments[2].equalsIgnoreCase("spawnable")
+                || !ENABLE_MODES.contains(arguments[3].toLowerCase(Locale.ROOT))) {
+            sender.sendMessage(ChatColor.RED + "Usage: /baseadmin setsetting <player> "
+                + "spawnable <enable|disable>");
+            return true;
+        }
+        boolean enabled = arguments[3].equalsIgnoreCase("enable");
+        if (enabled && target.totalBlocksPlaced()
+                < settingsProvider.current().spawnableOverlayUnlockPlacements()) {
+            sender.sendMessage(ChatColor.RED + "That player has not unlocked the spawnable overlay.");
+            return true;
+        }
+        if (enabled && (target.baseLevel() < 1 || target.base().isEmpty())) {
+            sender.sendMessage(ChatColor.RED + "That player does not have an established base.");
+            return true;
+        }
+        PlayerState updated = stateManager.update(
+            target.playerId(),
+            target.latestName(),
+            current -> current.withSpawnableOverlayEnabled(enabled)
+        );
+        stateManager.saveIfDirty();
+        sender.sendMessage(ChatColor.GREEN + "Set " + updated.latestName()
+            + "'s spawnable overlay to " + (enabled ? "enabled" : "disabled") + ".");
+        return true;
+    }
+
     private boolean clearCooldown(
         CommandSender sender,
         PlayerState target,
@@ -350,12 +394,16 @@ final class BaseAdminCommand implements CommandExecutor, TabCompleter {
             List<String> options = switch (arguments[0].toLowerCase(Locale.ROOT)) {
                 case "setlevel" -> PATHS;
                 case "setprogress" -> COUNTERS;
+                case "setsetting" -> SETTINGS;
                 case "clearcooldown" -> COOLDOWN_TYPES;
                 case "reset" -> RESET_PATHS;
                 default -> List.of();
             };
             return complete(options, arguments[2]);
         }
+        if (arguments.length == 4 && arguments[0].equalsIgnoreCase("setsetting")) {
+            return complete(ENABLE_MODES, arguments[3]);
+        }
         if (arguments.length == 4 && arguments[0].equalsIgnoreCase("setlevel")) {
             List<String> levels = switch (arguments[2].toLowerCase(Locale.ROOT)) {
                 case "base", "cooldown" -> LEVELS_FOUR;
@@ -386,7 +434,7 @@ final class BaseAdminCommand implements CommandExecutor, TabCompleter {
 
     private static void sendUsage(CommandSender sender) {
         sender.sendMessage(ChatColor.YELLOW + "Usage: /baseadmin "
-            + "<status|setlevel|setprogress|clearcooldown|reset> <player> ...");
+            + "<status|setlevel|setprogress|setsetting|clearcooldown|reset> <player> ...");
         sender.sendMessage(ChatColor.YELLOW + "       /baseadmin config <key> <integer>");
     }
 }

src/main/java/games/dmg/spigotbase/BaseFlightController.java

@@ -112,7 +112,7 @@ final class BaseFlightController implements Runnable {
             player.setAllowFlight(true);
             grantedFlight.add(player.getUniqueId());
         }
-        if (distanceSquared > (double) radius * radius) {
+        if (distanceSquared > (double) radius * radius && player.isFlying()) {
             if (warned.add(player.getUniqueId())) {
                 player.sendTitle(
                     ChatColor.RED + "Leaving Your Base",

src/main/java/games/dmg/spigotbase/BaseNavigationController.java

@@ -10,6 +10,7 @@ final class BaseNavigationController implements Runnable {
     private final Server server;
     private final BaseStateManager stateManager;
     private final PluginSettingsProvider settings;
+    private final BaseBoundsService boundsService;
 
     BaseNavigationController(
         Server server,
@@ -19,6 +20,7 @@ final class BaseNavigationController implements Runnable {
         this.server = server;
         this.stateManager = stateManager;
         this.settings = settings;
+        this.boundsService = new BaseBoundsService(settings);
     }
 
     @Override
@@ -32,7 +34,16 @@ final class BaseNavigationController implements Runnable {
             if (!player.getWorld().getUID().equals(base.worldId())) {
                 continue;
             }
-            Location origin = player.getLocation().clone().add(0.0, 0.15, 0.0);
+            Location playerLocation = player.getLocation();
+            if (!BaseNavigationVisibility.isBeyondBorderBuffer(
+                    base,
+                    boundsService.radius(state),
+                    playerLocation.getX(),
+                    playerLocation.getZ()
+            )) {
+                continue;
+            }
+            Location origin = playerLocation.clone().add(0.0, 0.15, 0.0);
             Vector direction = new Vector(
                 base.x() + 0.5 - origin.getX(),
                 0.0,

src/main/java/games/dmg/spigotbase/BaseNavigationVisibility.java

@@ -0,0 +1,26 @@
+package games.dmg.spigotbase;
+
+final class BaseNavigationVisibility {
+    static final int BORDER_BUFFER = 25;
+
+    private BaseNavigationVisibility() {
+    }
+
+    static boolean isBeyondBorderBuffer(
+        BaseLocation base,
+        int radius,
+        double playerX,
+        double playerZ
+    ) {
+        if (base == null) {
+            throw new IllegalArgumentException("base is required");
+        }
+        if (radius <= 0) {
+            throw new IllegalArgumentException("base radius must be positive");
+        }
+        double deltaX = playerX - (base.x() + 0.5);
+        double deltaZ = playerZ - (base.z() + 0.5);
+        double minimumDistance = radius + BORDER_BUFFER;
+        return deltaX * deltaX + deltaZ * deltaZ > minimumDistance * minimumDistance;
+    }
+}

src/main/java/games/dmg/spigotbase/BaseProgressListener.java

@@ -24,6 +24,7 @@ final class BaseProgressListener implements Listener {
     private final BaseProgressionService baseProgressionService;
     private final SecondaryProgressionService secondaryProgressionService;
     private final TeleportProgressionService teleportProgressionService;
+    private final SpawnableOverlayProgressionService spawnableOverlayProgressionService;
     private final BaseBoundsService boundsService;
     private final PluginSettingsProvider settings;
     private final Map<UUID, BossBar> activeBossBars = new HashMap<>();
@@ -34,6 +35,7 @@ final class BaseProgressListener implements Listener {
         BaseProgressionService baseProgressionService,
         SecondaryProgressionService secondaryProgressionService,
         TeleportProgressionService teleportProgressionService,
+        SpawnableOverlayProgressionService spawnableOverlayProgressionService,
         BaseBoundsService boundsService,
         PluginSettingsProvider settings
     ) {
@@ -42,6 +44,7 @@ final class BaseProgressListener implements Listener {
         this.baseProgressionService = baseProgressionService;
         this.secondaryProgressionService = secondaryProgressionService;
         this.teleportProgressionService = teleportProgressionService;
+        this.spawnableOverlayProgressionService = spawnableOverlayProgressionService;
         this.boundsService = boundsService;
         this.settings = settings;
     }
@@ -97,26 +100,43 @@ final class BaseProgressListener implements Listener {
             return;
         }
         PlayerState before = stateManager.player(player.getUniqueId(), player.getName());
-        if (!isInsideBase(
-                before,
-                event.getBlockPlaced().getWorld().getUID(),
-                event.getBlockPlaced().getX(),
-                event.getBlockPlaced().getY(),
-                event.getBlockPlaced().getZ())) {
-            return;
-        }
+        boolean insideBase = isInsideBase(
+            before,
+            event.getBlockPlaced().getWorld().getUID(),
+            event.getBlockPlaced().getX(),
+            event.getBlockPlaced().getY(),
+            event.getBlockPlaced().getZ()
+        );
         ProgressionUpdate[] updateHolder = new ProgressionUpdate[1];
+        SpawnableOverlayProgressionUpdate[] overlayHolder =
+            new SpawnableOverlayProgressionUpdate[1];
         PlayerState state = stateManager.update(player.getUniqueId(), player.getName(), current -> {
-            ProgressionUpdate update = teleportProgressionService.recordPlacement(current);
+            SpawnableOverlayProgressionUpdate overlay =
+                spawnableOverlayProgressionService.recordPlacement(current);
+            ProgressionUpdate update = insideBase
+                ? teleportProgressionService.recordPlacement(overlay.player())
+                : ProgressionUpdate.unchanged(overlay.player());
+            overlayHolder[0] = overlay;
             updateHolder[0] = update;
             return update.player();
         });
         ProgressionUpdate update = updateHolder[0];
+        SpawnableOverlayProgressionUpdate overlay = overlayHolder[0];
         announceUnlock(player, update);
-        if (hasUnlock(update)) {
+        if (overlay.unlocked()) {
+            sendUnlockTitle(
+                player,
+                ChatColor.GOLD + "Spawnable Overlay Unlocked",
+                ChatColor.YELLOW + "/basesettings spawnable enable is now available"
+            );
+            player.sendMessage(ChatColor.GREEN
+                + "You unlocked spawnable block highlighting! Use "
+                + "/basesettings spawnable enable.");
+        }
+        if (hasUnlock(update) || overlay.unlocked()) {
             stateManager.saveIfDirty();
         }
-        if (state.bossBarEnabled() && state.baseLevel() >= 2) {
+        if (insideBase && state.bossBarEnabled() && state.baseLevel() >= 2) {
             showProgress(player, warmupDisplay(state));
         }
     }

src/main/java/games/dmg/spigotbase/BaseSettingsCommand.java

@@ -15,7 +15,8 @@ import org.bukkit.inventory.PlayerInventory;
 
 final class BaseSettingsCommand implements CommandExecutor, TabCompleter {
     private static final List<String> SETTINGS = List.of(
-        "status", "upgrade", "visitors", "navigation", "flight", "border", "bossbar"
+        "status", "upgrade", "visitors", "navigation", "flight", "border", "spawnable",
+        "bossbar"
     );
     private static final List<String> VISITOR_MODES = List.of("allowed", "blocked");
     private static final List<String> ENABLE_MODES = List.of("enable", "disable");
@@ -62,6 +63,9 @@ final class BaseSettingsCommand implements CommandExecutor, TabCompleter {
         if (arguments.length == 2 && arguments[0].equalsIgnoreCase("border")) {
             return updateBorder(player, state, arguments[1]);
         }
+        if (arguments.length == 2 && arguments[0].equalsIgnoreCase("spawnable")) {
+            return updateSpawnableOverlay(player, state, arguments[1]);
+        }
         if (arguments.length == 2 && arguments[0].equalsIgnoreCase("bossbar")) {
             return updateBossBar(player, arguments[1]);
         }
@@ -215,6 +219,36 @@ final class BaseSettingsCommand implements CommandExecutor, TabCompleter {
         return true;
     }
 
+    private boolean updateSpawnableOverlay(Player player, PlayerState state, String mode) {
+        if (state.totalBlocksPlaced() < settings.current().spawnableOverlayUnlockPlacements()) {
+            player.sendMessage(ChatColor.RED + "Spawnable highlighting unlocks after "
+                + settings.current().spawnableOverlayUnlockPlacements() + " total placements.");
+            return true;
+        }
+        if (state.baseLevel() < 1 || state.base().isEmpty()) {
+            player.sendMessage(ChatColor.RED
+                + "Establish Base I before enabling spawnable highlighting.");
+            return true;
+        }
+        Boolean enabled = enabledMode(mode);
+        if (enabled == null) {
+            sendUsage(player);
+            return true;
+        }
+        state = stateManager.update(
+            player.getUniqueId(),
+            player.getName(),
+            current -> current.withSpawnableOverlayEnabled(enabled)
+        );
+        stateManager.saveIfDirty();
+        player.sendMessage(ChatColor.YELLOW + "Spawnable block highlighting is now "
+            + (state.spawnableOverlayEnabled()
+                ? ChatColor.GREEN + "enabled"
+                : ChatColor.RED + "disabled")
+            + ChatColor.YELLOW + ".");
+        return true;
+    }
+
     private boolean updateBossBar(Player player, String mode) {
         Boolean enabled = enabledMode(mode);
         if (enabled == null) {
@@ -240,11 +274,17 @@ final class BaseSettingsCommand implements CommandExecutor, TabCompleter {
         showFlightPath(player, state);
         showWarmupPath(player, state);
         showCooldownPath(player, state);
+        int spawnableThreshold = settings.current().spawnableOverlayUnlockPlacements();
+        player.sendMessage(ChatColor.YELLOW + "Spawnable Overlay: " + ChatColor.GRAY
+            + state.totalBlocksPlaced() + "/" + spawnableThreshold + " placements; "
+            + (state.totalBlocksPlaced() >= spawnableThreshold ? "unlocked" : "locked")
+            + "; setting=" + (state.spawnableOverlayEnabled() ? "enabled" : "disabled"));
         player.sendMessage(ChatColor.GRAY + "Settings: visitors="
             + (state.visitorsEnabled() ? "allowed" : "blocked")
             + " navigation=" + (state.navigationEnabled() ? "enabled" : "disabled")
             + " flight=" + (state.flightEnabled() ? "enabled" : "disabled")
             + " border=" + (state.borderEnabled() ? "enabled" : "disabled")
+            + " spawnable=" + (state.spawnableOverlayEnabled() ? "enabled" : "disabled")
             + " bossbar=" + (state.bossBarEnabled() ? "enabled" : "disabled"));
         state.base().ifPresentOrElse(
             base -> player.sendMessage(ChatColor.GRAY + "Base: " + base.worldName() + " "
@@ -333,7 +373,7 @@ final class BaseSettingsCommand implements CommandExecutor, TabCompleter {
             List<String> modes = arguments[0].equalsIgnoreCase("visitors")
                 ? VISITOR_MODES
                 : switch (arguments[0].toLowerCase(Locale.ROOT)) {
-                    case "navigation", "flight", "border", "bossbar" -> ENABLE_MODES;
+                    case "navigation", "flight", "border", "spawnable", "bossbar" -> ENABLE_MODES;
                     default -> List.of();
                 };
             String prefix = arguments[1].toLowerCase(Locale.ROOT);
@@ -399,6 +439,7 @@ final class BaseSettingsCommand implements CommandExecutor, TabCompleter {
     private static void sendUsage(Player player) {
         player.sendMessage(ChatColor.RED + "Usage: /basesettings "
             + "[status|upgrade|visitors <allowed|blocked>|navigation <enable|disable>"
-            + "|flight <enable|disable>|border <enable|disable>|bossbar <enable|disable>]");
+            + "|flight <enable|disable>|border <enable|disable>"
+            + "|spawnable <enable|disable>|bossbar <enable|disable>]");
     }
 }

src/main/java/games/dmg/spigotbase/BaseTeleportManager.java

@@ -83,6 +83,13 @@ final class BaseTeleportManager implements Listener {
             visitor.sendMessage(ChatColor.RED + "That base is not accepting visitors.");
             return;
         }
+        BaseLocation destination = owner.base().orElseThrow();
+        if (!visitor.getWorld().getUID().equals(destination.worldId())) {
+            visitor.sendMessage(
+                ChatColor.RED + "You must be in the same dimension as that base to visit it."
+            );
+            return;
+        }
         PlayerState visitorState = stateManager.player(visitor.getUniqueId(), visitor.getName());
         Optional<Duration> remaining = visitorPolicy.remaining(
             visitorState, owner.playerId(), clock.instant()
@@ -94,8 +101,8 @@ final class BaseTeleportManager implements Listener {
         }
         begin(
             visitor,
-            owner.base().orElseThrow(),
-            policy.warmup(owner),
+            destination,
+            policy.visitorWarmup(owner),
             owner.playerId(),
             policy.cooldown(owner),
             "visit " + owner.latestName() + "'s base"

src/main/java/games/dmg/spigotbase/PlayerState.java

@@ -27,7 +27,9 @@ public record PlayerState(
     Optional<Instant> lastBaseSet,
     Optional<Instant> lastBaseTeleport,
     Map<UUID, Instant> visitorCooldownUntil,
-    boolean borderEnabled
+    boolean borderEnabled,
+    long totalBlocksPlaced,
+    boolean spawnableOverlayEnabled
 ) {
     public PlayerState {
         if (playerId == null) {
@@ -54,6 +56,7 @@ public record PlayerState(
         requireNonNegative(obsidianBroken, "obsidian broken");
         requireNonNegative(blocksPlacedInBase, "blocks placed in base");
         requireNonNegative(blocksBrokenInBase, "blocks broken in base");
+        requireNonNegative(totalBlocksPlaced, "total blocks placed");
 
         if (baseLevel == 0 && (sizeLevel > 0 || flightLevel > 0)) {
             throw new IllegalArgumentException("secondary progression requires Base I");
@@ -73,6 +76,9 @@ public record PlayerState(
         if (borderEnabled && (baseLevel < 1 || base.isEmpty())) {
             throw new IllegalArgumentException("border visualization requires an established Base I");
         }
+        if (spawnableOverlayEnabled && (baseLevel < 1 || base.isEmpty())) {
+            throw new IllegalArgumentException("spawnable overlay requires an established Base I");
+        }
         if (visitorCooldownUntil.entrySet().stream().anyMatch(entry ->
                 entry.getKey() == null || entry.getValue() == null)) {
             throw new IllegalArgumentException("visitor cooldowns must be complete");
@@ -107,7 +113,40 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, false
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, false, 0, false
+        );
+    }
+
+    public PlayerState(
+        UUID playerId,
+        String latestName,
+        Optional<BaseLocation> base,
+        int baseLevel,
+        int sizeLevel,
+        int flightLevel,
+        int warmupLevel,
+        int cooldownLevel,
+        long grassAndDirtBroken,
+        long stoneBroken,
+        long deepslateBroken,
+        long obsidianBroken,
+        long blocksPlacedInBase,
+        long blocksBrokenInBase,
+        boolean navigationEnabled,
+        boolean flightEnabled,
+        boolean bossBarEnabled,
+        boolean visitorsEnabled,
+        Optional<Instant> lastBaseSet,
+        Optional<Instant> lastBaseTeleport,
+        Map<UUID, Instant> visitorCooldownUntil,
+        boolean borderEnabled
+    ) {
+        this(
+            playerId, latestName, base, baseLevel, sizeLevel, flightLevel,
+            warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
+            obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
+            navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled, 0, false
         );
     }
 
@@ -129,7 +168,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -139,7 +179,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, count, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -149,7 +190,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, enabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -159,7 +201,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             enabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -169,7 +212,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stone, deepslate,
             obsidian, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -179,7 +223,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, enabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -199,7 +244,8 @@ public record PlayerState(
             newWarmupLevel, newCooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, placements, breaks,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -215,7 +261,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, Optional.of(usedAt), visitorCooldownUntil, borderEnabled
+            lastBaseSet, Optional.of(usedAt), visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -225,7 +272,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -242,7 +290,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassDirt, stone, deepslate,
             obsidian, placements, baseBreaks,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -262,7 +311,9 @@ public record PlayerState(
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             newNavigationEnabled, newFlightEnabled, bossBarEnabled, newVisitorsEnabled,
             lastBaseSet, lastBaseTeleport, visitorCooldownUntil,
-            borderEnabled && newBaseLevel >= 1 && base.isPresent()
+            borderEnabled && newBaseLevel >= 1 && base.isPresent(),
+            totalBlocksPlaced,
+            spawnableOverlayEnabled && newBaseLevel >= 1 && base.isPresent()
         );
     }
 
@@ -272,7 +323,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, enabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -282,7 +334,30 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, enabled
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, enabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
+        );
+    }
+
+    public PlayerState withTotalBlocksPlaced(long count) {
+        return new PlayerState(
+            playerId, latestName, base, baseLevel, sizeLevel, flightLevel,
+            warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
+            obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
+            navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            count, spawnableOverlayEnabled
+        );
+    }
+
+    public PlayerState withSpawnableOverlayEnabled(boolean enabled) {
+        return new PlayerState(
+            playerId, latestName, base, baseLevel, sizeLevel, flightLevel,
+            warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
+            obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
+            navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
+            lastBaseSet, lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, enabled
         );
     }
 
@@ -294,7 +369,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, cooldowns, borderEnabled
+            lastBaseSet, lastBaseTeleport, cooldowns, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -304,7 +380,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, Optional.empty(), visitorCooldownUntil, borderEnabled
+            lastBaseSet, Optional.empty(), visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -314,7 +391,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            lastBaseSet, lastBaseTeleport, Map.of(), borderEnabled
+            lastBaseSet, lastBaseTeleport, Map.of(), borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 
@@ -324,7 +402,8 @@ public record PlayerState(
             warmupLevel, cooldownLevel, grassAndDirtBroken, stoneBroken, deepslateBroken,
             obsidianBroken, blocksPlacedInBase, blocksBrokenInBase,
             navigationEnabled, flightEnabled, bossBarEnabled, visitorsEnabled,
-            Optional.of(setAt), lastBaseTeleport, visitorCooldownUntil, borderEnabled
+            Optional.of(setAt), lastBaseTeleport, visitorCooldownUntil, borderEnabled,
+            totalBlocksPlaced, spawnableOverlayEnabled
         );
     }
 

src/main/java/games/dmg/spigotbase/PluginSettings.java

@@ -21,6 +21,7 @@ public record PluginSettings(
     int flightWarningBuffer,
     int secondFlightVerticalRange,
     int teleportUnlockPlacements,
+    int spawnableOverlayUnlockPlacements,
     int secondWarmupPlacements,
     int thirdWarmupPlacements,
     int instantWarmupPlacements,
@@ -62,6 +63,7 @@ public record PluginSettings(
     private static final int DEFAULT_FLIGHT_WARNING_BUFFER = 5;
     private static final int DEFAULT_SECOND_FLIGHT_VERTICAL_RANGE = 100;
     private static final int DEFAULT_TELEPORT_UNLOCK_PLACEMENTS = 200;
+    private static final int DEFAULT_SPAWNABLE_OVERLAY_UNLOCK_PLACEMENTS = 250;
     private static final int DEFAULT_SECOND_WARMUP_PLACEMENTS = 1_000;
     private static final int DEFAULT_THIRD_WARMUP_PLACEMENTS = 2_000;
     private static final int DEFAULT_INSTANT_WARMUP_PLACEMENTS = 12_000;
@@ -110,6 +112,7 @@ public record PluginSettings(
             throw new IllegalArgumentException("second-flight-vertical-range must exceed the initial range");
         }
         requirePositive(teleportUnlockPlacements, "teleport-unlock-placements");
+        requirePositive(spawnableOverlayUnlockPlacements, "spawnable-overlay-unlock-placements");
         if (secondWarmupPlacements <= teleportUnlockPlacements
                 || thirdWarmupPlacements <= secondWarmupPlacements
                 || instantWarmupPlacements <= thirdWarmupPlacements) {
@@ -175,6 +178,11 @@ public record PluginSettings(
             integer(values, "flight-warning-buffer", DEFAULT_FLIGHT_WARNING_BUFFER),
             integer(values, "second-flight-vertical-range", DEFAULT_SECOND_FLIGHT_VERTICAL_RANGE),
             integer(values, "teleport-unlock-placements", DEFAULT_TELEPORT_UNLOCK_PLACEMENTS),
+            integer(
+                values,
+                "spawnable-overlay-unlock-placements",
+                DEFAULT_SPAWNABLE_OVERLAY_UNLOCK_PLACEMENTS
+            ),
             integer(values, "second-warmup-placements", DEFAULT_SECOND_WARMUP_PLACEMENTS),
             integer(values, "third-warmup-placements", DEFAULT_THIRD_WARMUP_PLACEMENTS),
             integer(values, "instant-warmup-placements", DEFAULT_INSTANT_WARMUP_PLACEMENTS),

src/main/java/games/dmg/spigotbase/ProgressCounter.java

@@ -6,5 +6,6 @@ public enum ProgressCounter {
     DEEPSLATE,
     OBSIDIAN,
     PLACEMENTS,
+    TOTAL_PLACEMENTS,
     BASE_BREAKS
 }

src/main/java/games/dmg/spigotbase/SpawnableBlockPolicy.java

@@ -0,0 +1,38 @@
+package games.dmg.spigotbase;
+
+import org.bukkit.block.Block;
+import org.bukkit.block.BlockFace;
+import org.bukkit.block.data.Bisected;
+import org.bukkit.block.data.type.Slab;
+import org.bukkit.block.data.type.Stairs;
+
+final class SpawnableBlockPolicy {
+    private SpawnableBlockPolicy() {
+    }
+
+    static boolean isCandidate(Block surface) {
+        if (!hasSpawnableTop(surface)) {
+            return false;
+        }
+        Block above = surface.getRelative(BlockFace.UP);
+        Block secondAbove = above.getRelative(BlockFace.UP);
+        return isEmpty(above)
+            && isEmpty(secondAbove)
+            && above.getLightFromBlocks() == 0
+            && above.getLightFromSky() <= 7;
+    }
+
+    private static boolean hasSpawnableTop(Block block) {
+        if (block.getBlockData() instanceof Slab slab) {
+            return slab.getType() == Slab.Type.TOP || slab.getType() == Slab.Type.DOUBLE;
+        }
+        if (block.getBlockData() instanceof Stairs stairs) {
+            return stairs.getHalf() == Bisected.Half.TOP;
+        }
+        return block.getType().isOccluding();
+    }
+
+    private static boolean isEmpty(Block block) {
+        return block.isPassable() && !block.isLiquid();
+    }
+}

src/main/java/games/dmg/spigotbase/SpawnableOverlayController.java

@@ -0,0 +1,185 @@
+package games.dmg.spigotbase;
+
+import java.util.ArrayDeque;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import org.bukkit.Color;
+import org.bukkit.Location;
+import org.bukkit.Particle;
+import org.bukkit.Server;
+import org.bukkit.World;
+import org.bukkit.block.Block;
+import org.bukkit.entity.Player;
+
+final class SpawnableOverlayController implements Runnable {
+    static final int HORIZONTAL_RADIUS = 16;
+    static final int VERTICAL_RADIUS = 8;
+    static final int WORK_BUDGET = 2_048;
+    static final int PARTICLE_BUDGET = 128;
+    private static final int PENDING_BUDGET = PARTICLE_BUDGET * 4;
+    private static final int WIDTH = HORIZONTAL_RADIUS * 2 + 1;
+    private static final int HEIGHT = VERTICAL_RADIUS * 2 + 1;
+    private static final int TOTAL_POSITIONS = WIDTH * WIDTH * HEIGHT;
+    private static final Particle.DustOptions RED_DUST =
+        new Particle.DustOptions(Color.RED, 1.0F);
+
+    private final Server server;
+    private final BaseStateManager stateManager;
+    private final BaseBoundsService boundsService;
+    private final PluginSettingsProvider settings;
+    private final Map<UUID, ScanState> scans = new HashMap<>();
+
+    SpawnableOverlayController(
+        Server server,
+        BaseStateManager stateManager,
+        BaseBoundsService boundsService,
+        PluginSettingsProvider settings
+    ) {
+        this.server = server;
+        this.stateManager = stateManager;
+        this.boundsService = boundsService;
+        this.settings = settings;
+    }
+
+    @Override
+    public void run() {
+        Set<UUID> active = new HashSet<>();
+        for (Player player : server.getOnlinePlayers()) {
+            PlayerState playerState = stateManager.player(
+                player.getUniqueId(), player.getName()
+            );
+            if (!eligible(player, playerState)) {
+                scans.remove(player.getUniqueId());
+                continue;
+            }
+            active.add(player.getUniqueId());
+            updateAndRender(player, playerState);
+        }
+        scans.keySet().removeIf(playerId -> !active.contains(playerId));
+    }
+
+    private boolean eligible(Player player, PlayerState state) {
+        return state.spawnableOverlayEnabled()
+            && state.totalBlocksPlaced() >= settings.current()
+                .spawnableOverlayUnlockPlacements()
+            && state.base().isPresent()
+            && player.getWorld().getUID().equals(state.base().orElseThrow().worldId());
+    }
+
+    private void updateAndRender(Player player, PlayerState state) {
+        Location location = player.getLocation();
+        BaseLocation base = state.base().orElseThrow();
+        int centerX = location.getBlockX();
+        int centerY = location.getBlockY() - 1;
+        int centerZ = location.getBlockZ();
+        ScanOrigin origin = new ScanOrigin(
+            player.getWorld().getUID(), centerX, centerY, centerZ,
+            base.x(), base.y(), base.z(), boundsService.radius(state)
+        );
+        ScanState scan = scans.get(player.getUniqueId());
+        if (scan == null || !scan.origin.near(origin)) {
+            scan = new ScanState(origin);
+            scans.put(player.getUniqueId(), scan);
+        }
+        scan(player.getWorld(), boundsService.area(state), scan);
+        render(player, scan);
+    }
+
+    private static void scan(World world, BaseArea base, ScanState scan) {
+        int work = Math.min(WORK_BUDGET, TOTAL_POSITIONS);
+        int minimumWorldY = world.getMinHeight();
+        int maximumWorldY = world.getMaxHeight();
+        UUID worldId = world.getUID();
+        for (int offset = 0; offset < work; offset++) {
+            int index = (scan.cursor + offset) % TOTAL_POSITIONS;
+            int verticalIndex = index % HEIGHT;
+            int horizontalIndex = index / HEIGHT;
+            int zIndex = horizontalIndex % WIDTH;
+            int xIndex = horizontalIndex / WIDTH;
+            int x = scan.origin.centerX + xIndex - HORIZONTAL_RADIUS;
+            int y = scan.origin.centerY + verticalIndex - VERTICAL_RADIUS;
+            int z = scan.origin.centerZ + zIndex - HORIZONTAL_RADIUS;
+            BlockPosition position = new BlockPosition(x, y, z);
+            scan.spawnable.remove(position);
+            int deltaX = x - scan.origin.centerX;
+            int deltaZ = z - scan.origin.centerZ;
+            if (deltaX * deltaX + deltaZ * deltaZ
+                    > HORIZONTAL_RADIUS * HORIZONTAL_RADIUS
+                    || y < minimumWorldY
+                    || y >= maximumWorldY
+                    || !base.contains(worldId, x, y, z)) {
+                continue;
+            }
+            Block surface = world.getBlockAt(x, y, z);
+            if (SpawnableBlockPolicy.isCandidate(surface)) {
+                scan.spawnable.add(position);
+                if (scan.pending.size() < PENDING_BUDGET) {
+                    scan.pending.addLast(position);
+                }
+            }
+        }
+        scan.cursor = (scan.cursor + work) % TOTAL_POSITIONS;
+    }
+
+    private static void render(Player player, ScanState scan) {
+        for (int attempted = 0; attempted < PARTICLE_BUDGET; attempted++) {
+            BlockPosition position = scan.pending.pollFirst();
+            if (position == null) {
+                return;
+            }
+            if (!scan.spawnable.contains(position)) {
+                continue;
+            }
+            player.spawnParticle(
+                Particle.DUST,
+                new Location(
+                    player.getWorld(),
+                    position.x + 0.5,
+                    position.y + 1.05,
+                    position.z + 0.5
+                ),
+                1,
+                RED_DUST
+            );
+        }
+    }
+
+    private record BlockPosition(int x, int y, int z) {
+    }
+
+    private record ScanOrigin(
+        UUID worldId,
+        int centerX,
+        int centerY,
+        int centerZ,
+        int baseX,
+        int baseY,
+        int baseZ,
+        int baseRadius
+    ) {
+        boolean near(ScanOrigin other) {
+            return worldId.equals(other.worldId)
+                && Math.abs(centerX - other.centerX) <= 4
+                && Math.abs(centerY - other.centerY) <= 4
+                && Math.abs(centerZ - other.centerZ) <= 4
+                && baseX == other.baseX
+                && baseY == other.baseY
+                && baseZ == other.baseZ
+                && baseRadius == other.baseRadius;
+        }
+    }
+
+    private static final class ScanState {
+        private final ScanOrigin origin;
+        private final Set<BlockPosition> spawnable = new HashSet<>();
+        private final ArrayDeque<BlockPosition> pending = new ArrayDeque<>();
+        private int cursor;
+
+        private ScanState(ScanOrigin origin) {
+            this.origin = origin;
+        }
+    }
+}

src/main/java/games/dmg/spigotbase/SpawnableOverlayProgressionService.java

@@ -0,0 +1,19 @@
+package games.dmg.spigotbase;
+
+final class SpawnableOverlayProgressionService {
+    private final PluginSettingsProvider settings;
+
+    SpawnableOverlayProgressionService(PluginSettingsProvider settings) {
+        this.settings = settings;
+    }
+
+    SpawnableOverlayProgressionUpdate recordPlacement(PlayerState player) {
+        long previous = player.totalBlocksPlaced();
+        long updated = previous == Long.MAX_VALUE ? Long.MAX_VALUE : previous + 1;
+        int threshold = settings.current().spawnableOverlayUnlockPlacements();
+        return new SpawnableOverlayProgressionUpdate(
+            player.withTotalBlocksPlaced(updated),
+            previous < threshold && updated >= threshold
+        );
+    }
+}

src/main/java/games/dmg/spigotbase/SpawnableOverlayProgressionUpdate.java

@@ -0,0 +1,9 @@
+package games.dmg.spigotbase;
+
+record SpawnableOverlayProgressionUpdate(PlayerState player, boolean unlocked) {
+    SpawnableOverlayProgressionUpdate {
+        if (player == null) {
+            throw new IllegalArgumentException("player is required");
+        }
+    }
+}

src/main/java/games/dmg/spigotbase/SpigotBasePlugin.java

@@ -46,6 +46,7 @@ public final class SpigotBasePlugin extends JavaPlugin {
             progressionService,
             secondaryProgressionService,
             teleportProgressionService,
+            new SpawnableOverlayProgressionService(settingsProvider),
             boundsService,
             settingsProvider
         );
@@ -97,6 +98,14 @@ public final class SpigotBasePlugin extends JavaPlugin {
             10L,
             10L
         );
+        getServer().getScheduler().runTaskTimer(
+            this,
+            new SpawnableOverlayController(
+                getServer(), stateManager, boundsService, settingsProvider
+            ),
+            10L,
+            10L
+        );
         getServer().getScheduler().runTaskTimer(this, flightController, 5L, 5L);
         getServer().getScheduler().runTaskTimer(this, stateManager::saveIfDirty, 600L, 600L);
         getLogger().info("Spigot Base enabled.");

src/main/java/games/dmg/spigotbase/TeleportPolicy.java

@@ -25,6 +25,13 @@ public final class TeleportPolicy {
         };
     }
 
+    public Duration visitorWarmup(PlayerState owner) {
+        Duration warmup = warmup(owner);
+        return warmup.compareTo(Duration.ofSeconds(1)) < 0
+            ? Duration.ofSeconds(1)
+            : warmup;
+    }
+
     public Duration cooldown(PlayerState player) {
         return switch (player.cooldownLevel()) {
             case 0 -> Duration.ofSeconds(settings.current().initialTeleportCooldownSeconds());

src/main/java/games/dmg/spigotbase/YamlBaseStateRepository.java

@@ -128,7 +128,9 @@ public final class YamlBaseStateRepository {
                     instant(yaml, path + ".last-base-set-epoch-millis"),
                     instant(yaml, path + ".last-base-teleport-epoch-millis"),
                     loadVisitorCooldowns(yaml, path + ".visitor-cooldowns"),
-                    yaml.getBoolean(path + ".border-enabled", false)
+                    yaml.getBoolean(path + ".border-enabled", false),
+                    totalPlacementCount(yaml, path),
+                    yaml.getBoolean(path + ".spawnable-overlay-enabled", false)
                 );
                 players.put(playerId, player);
             } catch (IllegalArgumentException ignored) {
@@ -195,6 +197,13 @@ public final class YamlBaseStateRepository {
         return yaml.getLong(path);
     }
 
+    private static long totalPlacementCount(YamlConfiguration yaml, String playerPath) {
+        return Math.max(
+            count(yaml, playerPath + ".total-blocks-placed"),
+            count(yaml, playerPath + ".blocks-placed-in-base")
+        );
+    }
+
     private static Optional<Instant> instant(YamlConfiguration yaml, String path) {
         if (!yaml.isLong(path) && !yaml.isInt(path)) {
             return Optional.empty();
@@ -224,6 +233,8 @@ public final class YamlBaseStateRepository {
             yaml.set(path + ".boss-bar-enabled", player.bossBarEnabled());
             yaml.set(path + ".visitors-enabled", player.visitorsEnabled());
             yaml.set(path + ".border-enabled", player.borderEnabled());
+            yaml.set(path + ".total-blocks-placed", player.totalBlocksPlaced());
+            yaml.set(path + ".spawnable-overlay-enabled", player.spawnableOverlayEnabled());
             yaml.set(
                 path + ".last-base-set-epoch-millis",
                 player.lastBaseSet().map(Instant::toEpochMilli).orElse(null)

src/main/resources/config.yml

@@ -46,6 +46,9 @@ fourth-teleport-cooldown-seconds: 1800
 visitor-unlock-diamond-cost: 128
 visitor-currency-material: DIAMOND
 
+# Spawnable block overlay
+spawnable-overlay-unlock-placements: 250
+
 # Progress and notification presentation
 cooldown-excluded-materials: []
 boss-bar-duration-ticks: 60

src/main/resources/plugin.yml

@@ -19,7 +19,7 @@ commands:
     aliases: [visit]
   basesettings:
     description: View progression, upgrade, and manage base settings.
-    usage: /basesettings [status|upgrade|visitors|navigation|flight|border|bossbar]
+    usage: /basesettings [status|upgrade|visitors|navigation|flight|border|spawnable|bossbar]
     aliases: [homesettings]
   baseadmin:
     description: Administer Spigot Base.

src/test/java/games/dmg/spigotbase/AdminProgressCounterTest.java

@@ -11,6 +11,19 @@ final class AdminProgressCounterTest {
         new PluginSettingsProvider(PluginSettings.from(Map.of()))
     );
 
+    @Test
+    void settingTotalPlacementCounterUnlocksSpawnableOverlay() {
+        PlayerState player = PlayerState.newPlayer(UUID.randomUUID(), "Alex");
+
+        PlayerState updated = service.setProgress(
+            player,
+            ProgressCounter.TOTAL_PLACEMENTS,
+            250
+        );
+
+        assertEquals(250, updated.totalBlocksPlaced());
+    }
+
     @Test
     void settingPlacementCounterEvaluatesBaseAndWarmupTiers() {
         PlayerState player = PlayerState.newPlayer(UUID.randomUUID(), "Alex");

src/test/java/games/dmg/spigotbase/AdminProgressionServiceTest.java

@@ -53,6 +53,24 @@ final class AdminProgressionServiceTest {
         assertFalse(updated.borderEnabled());
     }
 
+    @Test
+    void completeResetClearsSpawnableOverlayProgressAndPreference() {
+        UUID playerId = UUID.randomUUID();
+        PlayerState player = PlayerState.newPlayer(playerId, "Alex")
+            .withAdministrativeLevels(1, 0, 0, 0, 0, false, false, false)
+            .withBase(
+                new BaseLocation(UUID.randomUUID(), "world", 0, 64, 0, 0, 0),
+                Instant.EPOCH
+            )
+            .withTotalBlocksPlaced(250)
+            .withSpawnableOverlayEnabled(true);
+
+        PlayerState updated = service.resetPath(player, ProgressionPath.BASE);
+
+        assertEquals(0, updated.totalBlocksPlaced());
+        assertFalse(updated.spawnableOverlayEnabled());
+    }
+
     @Test
     void rejectsUnknownLevel() {
         PlayerState player = PlayerState.newPlayer(UUID.randomUUID(), "Alex");

src/test/java/games/dmg/spigotbase/BaseAdminCommandTest.java

@@ -1,6 +1,7 @@
 package games.dmg.spigotbase;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.mock;
@@ -9,10 +10,13 @@ import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import java.time.Instant;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.UnaryOperator;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
@@ -22,6 +26,46 @@ import org.junit.jupiter.api.Test;
 import org.mockito.MockedStatic;
 
 final class BaseAdminCommandTest {
+    @Test
+    void adminCanEnableUnlockedSpawnableOverlayForPlayer() {
+        CommandSender sender = mock(CommandSender.class);
+        when(sender.hasPermission("spigotbase.admin")).thenReturn(true);
+        UUID playerId = UUID.randomUUID();
+        PlayerState target = PlayerState.newPlayer(playerId, "Builder")
+            .withAdministrativeLevels(1, 0, 0, 0, 0, false, false, false)
+            .withBase(
+                new BaseLocation(UUID.randomUUID(), "world", 0, 64, 0, 0, 0),
+                Instant.EPOCH
+            )
+            .withTotalBlocksPlaced(250);
+        AtomicReference<PlayerState> updated = new AtomicReference<>();
+        BaseStateManager stateManager = mock(BaseStateManager.class);
+        when(stateManager.findByName("Builder")).thenReturn(Optional.of(target));
+        when(stateManager.update(any(), anyString(), any())).thenAnswer(invocation -> {
+            @SuppressWarnings("unchecked")
+            UnaryOperator<PlayerState> operation = invocation.getArgument(2);
+            PlayerState result = operation.apply(target);
+            updated.set(result);
+            return result;
+        });
+        BaseAdminCommand command = new BaseAdminCommand(
+            mock(JavaPlugin.class),
+            stateManager,
+            new AdminProgressionService(
+                new PluginSettingsProvider(PluginSettings.from(Map.of()))
+            ),
+            new PluginSettingsProvider(PluginSettings.from(Map.of()))
+        );
+
+        try (MockedStatic<Bukkit> bukkit = mockStatic(Bukkit.class)) {
+            bukkit.when(() -> Bukkit.getPlayerExact("Builder")).thenReturn(null);
+            command.onCommand(sender, null, "baseadmin",
+                new String[] {"setsetting", "Builder", "spawnable", "enable"});
+        }
+
+        assertTrue(updated.get().spawnableOverlayEnabled());
+    }
+
     @Test
     void invalidPathShowsFriendlyUsage() {
         CommandSender sender = mock(CommandSender.class);
@@ -92,10 +136,23 @@ final class BaseAdminCommandTest {
                 new String[] {"setlevel", "Builder", ""})
         );
         assertEquals(
-            List.of("grass_dirt", "stone", "deepslate", "obsidian", "placements", "base_breaks"),
+            List.of(
+                "grass_dirt", "stone", "deepslate", "obsidian", "placements",
+                "total_placements", "base_breaks"
+            ),
             command.onTabComplete(sender, null, "baseadmin",
                 new String[] {"setprogress", "Builder", ""})
         );
+        assertEquals(
+            List.of("spawnable"),
+            command.onTabComplete(sender, null, "baseadmin",
+                new String[] {"setsetting", "Builder", ""})
+        );
+        assertEquals(
+            List.of("enable"),
+            command.onTabComplete(sender, null, "baseadmin",
+                new String[] {"setsetting", "Builder", "spawnable", "e"})
+        );
         assertEquals(
             List.of("personal", "visitor", "all"),
             command.onTabComplete(sender, null, "baseadmin",
@@ -108,6 +165,42 @@ final class BaseAdminCommandTest {
         );
     }
 
+    @Test
+    void adminCanChangeSpawnableOverlayUnlockThreshold() {
+        CommandSender sender = mock(CommandSender.class);
+        when(sender.hasPermission("spigotbase.admin")).thenReturn(true);
+        JavaPlugin plugin = mock(JavaPlugin.class);
+        FileConfiguration configuration = mock(FileConfiguration.class);
+        when(plugin.getConfig()).thenReturn(configuration);
+        when(configuration.get("spawnable-overlay-unlock-placements")).thenReturn(250);
+        when(configuration.getValues(false)).thenReturn(Map.of(
+            "spawnable-overlay-unlock-placements", 250
+        ));
+        PluginSettingsProvider settings = new PluginSettingsProvider(
+            PluginSettings.from(Map.of())
+        );
+        BaseAdminCommand command = new BaseAdminCommand(
+            plugin,
+            mock(BaseStateManager.class),
+            mock(AdminProgressionService.class),
+            settings
+        );
+
+        try (MockedStatic<PluginSettingsValidator> validator =
+                mockStatic(PluginSettingsValidator.class)) {
+            validator.when(() -> PluginSettingsValidator.validateMaterials(
+                any(PluginSettings.class)
+            )).thenAnswer(invocation -> invocation.getArgument(0));
+            command.onCommand(sender, null, "baseadmin", new String[] {
+                "config", "spawnable-overlay-unlock-placements", "500"
+            });
+        }
+
+        verify(configuration).set("spawnable-overlay-unlock-placements", 500L);
+        verify(plugin).saveConfig();
+        assertEquals(500, settings.current().spawnableOverlayUnlockPlacements());
+    }
+
     @Test
     void autocompletesNumericConfigurationKeys() {
         CommandSender sender = mock(CommandSender.class);
@@ -169,7 +262,10 @@ final class BaseAdminCommandTest {
         );
 
         assertEquals(
-            List.of("status", "setlevel", "setprogress", "clearcooldown", "reset", "config"),
+            List.of(
+                "status", "setlevel", "setprogress", "setsetting", "clearcooldown", "reset",
+                "config"
+            ),
             command.onTabComplete(sender, null, "baseadmin", new String[] {""})
         );
     }

src/test/java/games/dmg/spigotbase/BaseFlightControllerTest.java

@@ -0,0 +1,93 @@
+package games.dmg.spigotbase;
+
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import org.bukkit.Location;
+import org.bukkit.Server;
+import org.bukkit.World;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+final class BaseFlightControllerTest {
+    private final UUID playerId = UUID.randomUUID();
+    private final UUID worldId = UUID.randomUUID();
+    private final Server server = mock(Server.class);
+    private final BaseStateManager stateManager = mock(BaseStateManager.class);
+    private final Player player = mock(Player.class);
+    private final PlayerState state = PlayerState.newPlayer(playerId, "Alex")
+        .withGrassAndDirtProgress(250, 1)
+        .withBase(new BaseLocation(worldId, "world", 0, 64, 0, 0, 0), Instant.EPOCH)
+        .withFlightLevel(1, true);
+    private final BaseFlightController controller = new BaseFlightController(
+        server,
+        stateManager,
+        new SecondaryProgressionService(PluginSettings.from(Map.of())),
+        new BaseBoundsService(PluginSettings.from(Map.of())),
+        new PluginSettingsProvider(PluginSettings.from(Map.of()))
+    );
+
+    @BeforeEach
+    void setUp() {
+        World world = mock(World.class);
+        Location location = mock(Location.class);
+        PlayerInventory inventory = mock(PlayerInventory.class);
+
+        doReturn(List.of(player)).when(server).getOnlinePlayers();
+        when(player.getUniqueId()).thenReturn(playerId);
+        when(player.getName()).thenReturn("Alex");
+        when(player.getGameMode()).thenReturn(org.bukkit.GameMode.SURVIVAL);
+        when(player.getInventory()).thenReturn(inventory);
+        when(inventory.getStorageContents()).thenReturn(new ItemStack[0]);
+        when(stateManager.player(playerId, "Alex")).thenReturn(state);
+        when(player.getWorld()).thenReturn(world);
+        when(world.getUID()).thenReturn(worldId);
+        when(player.getLocation()).thenReturn(location);
+        when(location.getX()).thenReturn(12.5);
+        when(location.getZ()).thenReturn(0.5);
+        when(location.getBlockY()).thenReturn(64);
+        when(player.getAllowFlight()).thenReturn(true);
+    }
+
+    @Test
+    void walkingInWarningBufferDoesNotShowLeavingBaseWarning() {
+        when(player.isFlying()).thenReturn(false);
+
+        controller.run();
+
+        verify(player, never()).sendTitle(anyString(), anyString(), anyInt(), anyInt(), anyInt());
+    }
+
+    @Test
+    void flyingInWarningBufferShowsLeavingBaseWarning() {
+        when(player.isFlying()).thenReturn(true);
+
+        controller.run();
+
+        verify(player).sendTitle(anyString(), anyString(), anyInt(), anyInt(), anyInt());
+    }
+
+    @Test
+    void warningCanAppearAgainAfterPlayerStopsAndResumesFlyingInBuffer() {
+        when(player.isFlying()).thenReturn(true, false, true);
+
+        controller.run();
+        controller.run();
+        controller.run();
+
+        verify(player, times(2)).sendTitle(anyString(), anyString(), anyInt(), anyInt(), anyInt());
+    }
+}

src/test/java/games/dmg/spigotbase/BaseNavigationControllerTest.java

@@ -0,0 +1,60 @@
+package games.dmg.spigotbase;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.time.Instant;
+import java.util.Map;
+import java.util.UUID;
+import org.bukkit.Location;
+import org.bukkit.Particle;
+import org.bukkit.Server;
+import org.bukkit.World;
+import org.bukkit.entity.Player;
+import org.junit.jupiter.api.Test;
+
+final class BaseNavigationControllerTest {
+    @Test
+    void showsParticlesOnlyMoreThanTwentyFiveBlocksBeyondBorder() {
+        UUID playerId = UUID.randomUUID();
+        UUID worldId = UUID.randomUUID();
+        PlayerState state = PlayerState.newPlayer(playerId, "Builder")
+            .withAdministrativeLevels(2, 0, 0, 0, 0, true, false, false)
+            .withBase(new BaseLocation(worldId, "world", 0, 64, 0, 0, 0), Instant.EPOCH);
+        World world = mock(World.class);
+        when(world.getUID()).thenReturn(worldId);
+        Player player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(playerId);
+        when(player.getName()).thenReturn("Builder");
+        when(player.getWorld()).thenReturn(world);
+        when(player.getLocation()).thenReturn(new Location(world, 35.5, 64.0, 0.5));
+        Server server = mock(Server.class);
+        doReturn(java.util.List.of(player)).when(server).getOnlinePlayers();
+        BaseStateManager stateManager = mock(BaseStateManager.class);
+        when(stateManager.player(playerId, "Builder")).thenReturn(state);
+        PluginSettingsProvider settings = new PluginSettingsProvider(
+            PluginSettings.from(Map.of())
+        );
+
+        new BaseNavigationController(server, stateManager, settings).run();
+
+        verify(player, never()).spawnParticle(
+            eq(Particle.END_ROD), any(Location.class), eq(1),
+            eq(0.0), eq(0.0), eq(0.0), eq(0.0)
+        );
+
+        when(player.getLocation()).thenReturn(new Location(world, 35.51, 64.0, 0.5));
+        new BaseNavigationController(server, stateManager, settings).run();
+
+        verify(player, times(settings.current().navigationParticleCount())).spawnParticle(
+            eq(Particle.END_ROD), any(Location.class), eq(1),
+            eq(0.0), eq(0.0), eq(0.0), eq(0.0)
+        );
+    }
+}

src/test/java/games/dmg/spigotbase/BaseNavigationVisibilityTest.java

@@ -0,0 +1,26 @@
+package games.dmg.spigotbase;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.UUID;
+import org.junit.jupiter.api.Test;
+
+final class BaseNavigationVisibilityTest {
+    private static final BaseLocation BASE = new BaseLocation(
+        UUID.randomUUID(), "world", 0, 64, 0, 0, 0
+    );
+
+    @Test
+    void hidesNavigationAtAndWithinTwentyFiveBlocksBeyondBorder() {
+        assertFalse(BaseNavigationVisibility.isBeyondBorderBuffer(BASE, 10, 35.5, 0.5));
+        assertFalse(BaseNavigationVisibility.isBeyondBorderBuffer(BASE, 10, 20.5, 0.5));
+    }
+
+    @Test
+    void showsNavigationMoreThanTwentyFiveBlocksBeyondCurrentBorder() {
+        assertTrue(BaseNavigationVisibility.isBeyondBorderBuffer(BASE, 10, 35.51, 0.5));
+        assertFalse(BaseNavigationVisibility.isBeyondBorderBuffer(BASE, 75, 100.5, 0.5));
+        assertTrue(BaseNavigationVisibility.isBeyondBorderBuffer(BASE, 75, 100.51, 0.5));
+    }
+}

src/test/java/games/dmg/spigotbase/BaseProgressListenerTest.java

@@ -0,0 +1,66 @@
+package games.dmg.spigotbase;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.UnaryOperator;
+import org.bukkit.GameMode;
+import org.bukkit.World;
+import org.bukkit.block.Block;
+import org.bukkit.entity.Player;
+import org.bukkit.event.block.BlockPlaceEvent;
+import org.bukkit.plugin.Plugin;
+import org.junit.jupiter.api.Test;
+
+final class BaseProgressListenerTest {
+    @Test
+    void survivalPlacementOutsideBaseCountsTowardOverlayUnlock() {
+        UUID playerId = UUID.randomUUID();
+        PlayerState current = PlayerState.newPlayer(playerId, "Builder");
+        AtomicReference<PlayerState> updated = new AtomicReference<>();
+        BaseStateManager stateManager = mock(BaseStateManager.class);
+        when(stateManager.player(playerId, "Builder")).thenReturn(current);
+        when(stateManager.update(any(), anyString(), any())).thenAnswer(invocation -> {
+            @SuppressWarnings("unchecked")
+            UnaryOperator<PlayerState> operation = invocation.getArgument(2);
+            PlayerState result = operation.apply(current);
+            updated.set(result);
+            return result;
+        });
+        Player player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(playerId);
+        when(player.getName()).thenReturn("Builder");
+        when(player.getGameMode()).thenReturn(GameMode.SURVIVAL);
+        World world = mock(World.class);
+        when(world.getUID()).thenReturn(UUID.randomUUID());
+        Block block = mock(Block.class);
+        when(block.getWorld()).thenReturn(world);
+        BlockPlaceEvent event = mock(BlockPlaceEvent.class);
+        when(event.getPlayer()).thenReturn(player);
+        when(event.getBlockPlaced()).thenReturn(block);
+        PluginSettingsProvider settings = new PluginSettingsProvider(
+            PluginSettings.from(Map.of())
+        );
+        BaseProgressListener listener = new BaseProgressListener(
+            mock(Plugin.class),
+            stateManager,
+            mock(BaseProgressionService.class),
+            mock(SecondaryProgressionService.class),
+            mock(TeleportProgressionService.class),
+            new SpawnableOverlayProgressionService(settings),
+            new BaseBoundsService(settings),
+            settings
+        );
+
+        listener.onBlockPlace(event);
+
+        assertEquals(1, updated.get().totalBlocksPlaced());
+        assertEquals(0, updated.get().blocksPlacedInBase());
+    }
+}

src/test/java/games/dmg/spigotbase/BaseSettingsCommandTest.java

@@ -24,6 +24,22 @@ import org.bukkit.inventory.PlayerInventory;
 import org.junit.jupiter.api.Test;
 
 final class BaseSettingsCommandTest {
+    @Test
+    void spawnableEnableIsIdempotentAfterUnlock() {
+        UUID playerId = UUID.randomUUID();
+        PlayerState current = PlayerState.newPlayer(playerId, "Builder")
+            .withAdministrativeLevels(1, 0, 0, 0, 0, false, false, false)
+            .withBase(
+                new BaseLocation(UUID.randomUUID(), "world", 0, 64, 0, 0, 0),
+                Instant.EPOCH
+            )
+            .withTotalBlocksPlaced(250);
+
+        CommandResult result = execute(current, "spawnable", "enable");
+
+        assertTrue(result.updated().spawnableOverlayEnabled());
+    }
+
     @Test
     void borderEnableIsIdempotent() {
         UUID playerId = UUID.randomUUID();
@@ -73,7 +89,7 @@ final class BaseSettingsCommandTest {
             List.of("allowed"),
             command.onTabComplete(null, null, "basesettings", new String[] {"visitors", "a"})
         );
-        for (String setting : List.of("navigation", "flight", "border", "bossbar")) {
+        for (String setting : List.of("navigation", "flight", "border", "spawnable", "bossbar")) {
             assertEquals(
                 List.of("disable"),
                 command.onTabComplete(null, null, "basesettings", new String[] {setting, "d"})
@@ -90,7 +106,10 @@ final class BaseSettingsCommandTest {
         );
 
         assertEquals(
-            List.of("status", "upgrade", "visitors", "navigation", "flight", "border", "bossbar"),
+            List.of(
+                "status", "upgrade", "visitors", "navigation", "flight", "border",
+                "spawnable", "bossbar"
+            ),
             command.onTabComplete(null, null, "basesettings", new String[] {""})
         );
     }
@@ -204,12 +223,20 @@ final class BaseSettingsCommandTest {
         command.onCommand(player, null, "basesettings", new String[] {"status"});
 
         verify(player, times(2)).sendMessage(ChatColor.GOLD + "=== Base Progress ===");
+        verify(player, times(2)).sendMessage(
+            org.mockito.ArgumentMatchers.<String>argThat(message ->
+                message.contains("Spawnable Overlay:")
+                    && message.contains("0/250 placements")
+                    && message.contains("locked")
+            )
+        );
         verify(player, times(2)).sendMessage(
             org.mockito.ArgumentMatchers.<String>argThat(message ->
             message.contains("Settings: visitors=")
                 && message.contains("navigation=")
                 && message.contains("flight=")
                 && message.contains("border=")
+                && message.contains("spawnable=")
                 && message.contains("bossbar=")
             )
         );

src/test/java/games/dmg/spigotbase/BaseTeleportManagerTest.java

@@ -0,0 +1,64 @@
+package games.dmg.spigotbase;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.when;
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Optional;
+import java.util.UUID;
+import org.bukkit.ChatColor;
+import org.bukkit.World;
+import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
+import org.junit.jupiter.api.Test;
+
+final class BaseTeleportManagerTest {
+    @Test
+    void visitFromAnotherWorldIsRejectedBeforeWarmupAndCooldownChecks() {
+        UUID visitorId = UUID.randomUUID();
+        UUID ownerId = UUID.randomUUID();
+        UUID baseWorldId = UUID.randomUUID();
+        BaseStateManager stateManager = mock(BaseStateManager.class);
+        TeleportPolicy teleportPolicy = mock(TeleportPolicy.class);
+        VisitorPolicy visitorPolicy = mock(VisitorPolicy.class);
+        Player visitor = mock(Player.class);
+        World visitorWorld = mock(World.class);
+        PlayerState owner = PlayerState.newPlayer(ownerId, "Owner")
+            .withGrassAndDirtProgress(500, 4)
+            .withBase(
+                new BaseLocation(baseWorldId, "world", 0, 64, 0, 0, 0),
+                Instant.EPOCH
+            )
+            .withVisitorsEnabled(true);
+        PlayerState visitorState = PlayerState.newPlayer(visitorId, "Visitor");
+        BaseTeleportManager manager = new BaseTeleportManager(
+            mock(Plugin.class),
+            stateManager,
+            teleportPolicy,
+            visitorPolicy,
+            mock(SafeBaseDestination.class),
+            Clock.systemUTC()
+        );
+
+        when(visitor.getUniqueId()).thenReturn(visitorId);
+        when(visitor.getName()).thenReturn("Visitor");
+        when(visitor.getWorld()).thenReturn(visitorWorld);
+        when(visitorWorld.getUID()).thenReturn(UUID.randomUUID());
+        when(stateManager.player(visitorId, "Visitor")).thenReturn(visitorState);
+        when(visitorPolicy.remaining(eq(visitorState), eq(ownerId), any()))
+            .thenReturn(Optional.of(Duration.ofSeconds(1)));
+
+        manager.startVisit(visitor, owner);
+
+        verify(visitor).sendMessage(
+            ChatColor.RED + "You must be in the same dimension as that base to visit it."
+        );
+        verifyNoInteractions(stateManager, teleportPolicy, visitorPolicy);
+    }
+}

src/test/java/games/dmg/spigotbase/PlayerStateTest.java

@@ -11,6 +11,23 @@ import java.util.UUID;
 import org.junit.jupiter.api.Test;
 
 final class PlayerStateTest {
+    @Test
+    void spawnableOverlayProgressAndPreferenceCanBeUpdated() {
+        PlayerState player = PlayerState.newPlayer(UUID.randomUUID(), "Alex")
+            .withAdministrativeLevels(1, 0, 0, 0, 0, false, false, false)
+            .withBase(
+                new BaseLocation(UUID.randomUUID(), "world", 0, 64, 0, 0, 0),
+                Instant.EPOCH
+            );
+
+        PlayerState updated = player
+            .withTotalBlocksPlaced(250)
+            .withSpawnableOverlayEnabled(true);
+
+        assertTrue(updated.spawnableOverlayEnabled());
+        assertTrue(updated.totalBlocksPlaced() == 250);
+    }
+
     @Test
     void borderVisualizationIsDisabledByDefaultAndCanBeEnabled() {
         UUID playerId = UUID.randomUUID();

src/test/java/games/dmg/spigotbase/PluginSettingsTest.java

@@ -18,6 +18,7 @@ final class PluginSettingsTest {
         assertEquals(86_400L, settings.relocationCooldownSeconds());
         assertEquals(5, settings.flightWarningBuffer());
         assertEquals(200, settings.teleportUnlockPlacements());
+        assertEquals(250, settings.spawnableOverlayUnlockPlacements());
         assertEquals(10_800L, settings.initialTeleportCooldownSeconds());
         assertEquals(128, settings.visitorUnlockDiamondCost());
     }

src/test/java/games/dmg/spigotbase/SpawnableBlockPolicyTest.java

@@ -0,0 +1,48 @@
+package games.dmg.spigotbase;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import org.bukkit.block.Block;
+import org.bukkit.block.BlockFace;
+import org.bukkit.block.data.type.Slab;
+import org.junit.jupiter.api.Test;
+
+final class SpawnableBlockPolicyTest {
+    @Test
+    void acceptsDarkSolidSurfaceWithTwoPassableBlocksAbove() {
+        Block surface = mock(Block.class);
+        Block above = mock(Block.class);
+        Block secondAbove = mock(Block.class);
+        Slab slab = mock(Slab.class);
+        when(slab.getType()).thenReturn(Slab.Type.TOP);
+        when(surface.getBlockData()).thenReturn(slab);
+        when(surface.getRelative(BlockFace.UP)).thenReturn(above);
+        when(above.getRelative(BlockFace.UP)).thenReturn(secondAbove);
+        when(above.isPassable()).thenReturn(true);
+        when(secondAbove.isPassable()).thenReturn(true);
+        when(above.getLightFromBlocks()).thenReturn((byte) 0);
+        when(above.getLightFromSky()).thenReturn((byte) 0);
+
+        assertTrue(SpawnableBlockPolicy.isCandidate(surface));
+    }
+
+    @Test
+    void rejectsBlockLitSurface() {
+        Block surface = mock(Block.class);
+        Block above = mock(Block.class);
+        Block secondAbove = mock(Block.class);
+        Slab slab = mock(Slab.class);
+        when(slab.getType()).thenReturn(Slab.Type.TOP);
+        when(surface.getBlockData()).thenReturn(slab);
+        when(surface.getRelative(BlockFace.UP)).thenReturn(above);
+        when(above.getRelative(BlockFace.UP)).thenReturn(secondAbove);
+        when(above.isPassable()).thenReturn(true);
+        when(secondAbove.isPassable()).thenReturn(true);
+        when(above.getLightFromBlocks()).thenReturn((byte) 1);
+
+        assertFalse(SpawnableBlockPolicy.isCandidate(surface));
+    }
+}

src/test/java/games/dmg/spigotbase/SpawnableOverlayControllerTest.java

@@ -0,0 +1,85 @@
+package games.dmg.spigotbase;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.time.Instant;
+import java.util.Map;
+import java.util.UUID;
+import org.bukkit.Location;
+import org.bukkit.Particle;
+import org.bukkit.Server;
+import org.bukkit.World;
+import org.bukkit.block.Block;
+import org.bukkit.block.BlockFace;
+import org.bukkit.block.data.type.Slab;
+import org.bukkit.entity.Player;
+import org.junit.jupiter.api.Test;
+
+final class SpawnableOverlayControllerTest {
+    @Test
+    void ownerReceivesBoundedRedParticlesForNearbyCandidates() {
+        UUID playerId = UUID.randomUUID();
+        UUID worldId = UUID.randomUUID();
+        PlayerState state = PlayerState.newPlayer(playerId, "Builder")
+            .withAdministrativeLevels(1, 0, 0, 0, 0, false, false, false)
+            .withBase(new BaseLocation(worldId, "world", 0, 64, 0, 0, 0), Instant.EPOCH)
+            .withTotalBlocksPlaced(250)
+            .withSpawnableOverlayEnabled(true);
+
+        Block surface = mock(Block.class);
+        Block above = mock(Block.class);
+        Block secondAbove = mock(Block.class);
+        Slab slab = mock(Slab.class);
+        when(slab.getType()).thenReturn(Slab.Type.TOP);
+        when(surface.getBlockData()).thenReturn(slab);
+        when(surface.getRelative(BlockFace.UP)).thenReturn(above);
+        when(above.getRelative(BlockFace.UP)).thenReturn(secondAbove);
+        when(above.isPassable()).thenReturn(true);
+        when(secondAbove.isPassable()).thenReturn(true);
+        when(above.getLightFromBlocks()).thenReturn((byte) 0);
+        when(above.getLightFromSky()).thenReturn((byte) 0);
+
+        World world = mock(World.class);
+        when(world.getUID()).thenReturn(worldId);
+        when(world.getMinHeight()).thenReturn(-64);
+        when(world.getMaxHeight()).thenReturn(320);
+        when(world.getBlockAt(anyInt(), anyInt(), anyInt()))
+            .thenReturn(surface);
+        Player player = mock(Player.class);
+        when(player.getUniqueId()).thenReturn(playerId);
+        when(player.getName()).thenReturn("Builder");
+        when(player.getWorld()).thenReturn(world);
+        when(player.getLocation()).thenReturn(new Location(world, 0.5, 65.0, 0.5));
+        Server server = mock(Server.class);
+        doReturn(java.util.List.of(player)).when(server).getOnlinePlayers();
+        BaseStateManager stateManager = mock(BaseStateManager.class);
+        when(stateManager.player(playerId, "Builder")).thenReturn(state);
+        PluginSettingsProvider settings = new PluginSettingsProvider(
+            PluginSettings.from(Map.of())
+        );
+
+        SpawnableOverlayController controller = new SpawnableOverlayController(
+            server,
+            stateManager,
+            new BaseBoundsService(settings),
+            settings
+        );
+        controller.run();
+        controller.run();
+        controller.run();
+
+        verify(player, atLeastOnce()).spawnParticle(
+            eq(Particle.DUST),
+            any(Location.class),
+            eq(1),
+            any(Particle.DustOptions.class)
+        );
+    }
+}

src/test/java/games/dmg/spigotbase/SpawnableOverlayProgressionServiceTest.java

@@ -0,0 +1,24 @@
+package games.dmg.spigotbase;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Map;
+import java.util.UUID;
+import org.junit.jupiter.api.Test;
+
+final class SpawnableOverlayProgressionServiceTest {
+    @Test
+    void twoHundredFiftiethPlacementUnlocksOverlay() {
+        PlayerState player = PlayerState.newPlayer(UUID.randomUUID(), "Builder")
+            .withTotalBlocksPlaced(249);
+        SpawnableOverlayProgressionService service = new SpawnableOverlayProgressionService(
+            new PluginSettingsProvider(PluginSettings.from(Map.of()))
+        );
+
+        SpawnableOverlayProgressionUpdate update = service.recordPlacement(player);
+
+        assertEquals(250, update.player().totalBlocksPlaced());
+        assertTrue(update.unlocked());
+    }
+}

src/test/java/games/dmg/spigotbase/TeleportPolicyTest.java

@@ -22,6 +22,17 @@ final class TeleportPolicyTest {
         assertEquals(Duration.ZERO, policy.warmup(player.withTeleportLevels(3, 0)));
     }
 
+    @Test
+    void visitorWarmupHasOneSecondMinimum() {
+        PlayerState player = baseThreePlayer();
+
+        assertEquals(Duration.ofSeconds(30), policy.visitorWarmup(player));
+        assertEquals(
+            Duration.ofSeconds(1),
+            policy.visitorWarmup(player.withTeleportLevels(3, 0))
+        );
+    }
+
     @Test
     void cooldownLevelsUseApprovedDurations() {
         PlayerState player = baseThreePlayer();

src/test/java/games/dmg/spigotbase/YamlBaseStateRepositoryTest.java

@@ -29,6 +29,8 @@ final class YamlBaseStateRepositoryTest {
             Optional.of(Instant.ofEpochMilli(1_750_000_000_000L)),
             Optional.of(Instant.ofEpochMilli(1_750_000_100_000L)),
             Map.of(ownerId, Instant.ofEpochMilli(1_750_001_000_000L)),
+            true,
+            2_500,
             true
         );
         PersistentState expected = new PersistentState(Map.of(playerId, player));
@@ -40,6 +42,26 @@ final class YamlBaseStateRepositoryTest {
         assertEquals(expected, repository.load());
     }
 
+    @Test
+    void olderStateUsesKnownInBasePlacementsAsTotalPlacementMinimum() throws Exception {
+        UUID playerId = UUID.randomUUID();
+        Path stateFile = temporaryDirectory.resolve("state.yml");
+        Files.writeString(stateFile, """
+            players:
+              %s:
+                name: Alex
+                blocks-placed-in-base: 225
+            """.formatted(playerId));
+
+        PlayerState player = new YamlBaseStateRepository(stateFile)
+            .load()
+            .players()
+            .get(playerId);
+
+        assertEquals(225, player.totalBlocksPlaced());
+        assertFalse(player.spawnableOverlayEnabled());
+    }
+
     @Test
     void olderStateWithoutBorderPreferenceDefaultsToDisabled() throws Exception {
         UUID playerId = UUID.randomUUID();