diff --git a/resources/lang/en.json b/resources/lang/en.json
index 5135cc399..e119dae09 100644
--- a/resources/lang/en.json
+++ b/resources/lang/en.json
@@ -703,6 +703,8 @@
     "coordinate_grid_desc": "Toggle the alphanumeric grid overlay",
     "attacking_troops_overlay_label": "Attacking Troops Overlay",
     "attacking_troops_overlay_desc": "Show attacker vs defender troop counts on active front lines.",
+    "territory_border_mode_label": "Territory Borders",
+    "territory_border_mode_desc": "Select border rendering style (visual only)",
     "performance_overlay_label": "Performance Overlay",
     "performance_overlay_desc": "Toggle the performance overlay. When enabled, the performance overlay will be displayed. Press shift-D during game to toggle.",
     "easter_writing_speed_label": "Writing Speed Multiplier",
diff --git a/src/client/UserSettingModal.ts b/src/client/UserSettingModal.ts
index 60d434dbf..6f6ddb698 100644
--- a/src/client/UserSettingModal.ts
+++ b/src/client/UserSettingModal.ts
@@ -300,6 +300,16 @@ export class UserSettingModal extends BaseModal {
     this.requestUpdate();
   }
 
+  private changeTerritoryBorderMode(e: CustomEvent<{ value: number | string }>) {
+    const rawValue = e.detail?.value;
+    const value =
+      typeof rawValue === "number" ? rawValue : parseInt(String(rawValue), 10);
+    if (!Number.isFinite(value)) return;
+
+    this.userSettings.setInt("settings.territoryBorderMode", Math.round(value));
+    this.requestUpdate();
+  }
+
   private toggleTerritoryPatterns() {
     this.userSettings.toggleTerritoryPatterns();
 
@@ -752,6 +762,21 @@ export class UserSettingModal extends BaseModal {
       ></setting-toggle>
 
       <!-- 😊 Emojis -->
+      <setting-select
+        label="${translateText("user_setting.territory_border_mode_label")}"
+        description="${translateText(
+          "user_setting.territory_border_mode_desc",
+        )}"
+        id="territory-border-mode-select"
+        .value=${String(this.userSettings.territoryBorderMode())}
+        .options=${[
+          { value: 0, label: "Off" },
+          { value: 1, label: "Simple" },
+          { value: 2, label: "Glow" },
+        ]}
+        @change=${this.changeTerritoryBorderMode}
+      ></setting-select>
+
       <setting-toggle
         label="${translateText("user_setting.emojis_label")}"
         description="${translateText("user_setting.emojis_desc")}"
diff --git a/src/client/components/baseComponents/setting/SettingSelect.ts b/src/client/components/baseComponents/setting/SettingSelect.ts
index c36a8e1d7..290d5b615 100644
--- a/src/client/components/baseComponents/setting/SettingSelect.ts
+++ b/src/client/components/baseComponents/setting/SettingSelect.ts
@@ -1,7 +1,7 @@
-import { LitElement, html } from "lit";
+import { html, LitElement } from "lit";
 import { customElement, property } from "lit/decorators.js";
 
-type SelectOption = {
+export type SettingSelectOption = {
   value: number | string;
   label: string;
 };
@@ -10,8 +10,10 @@ type SelectOption = {
 export class SettingSelect extends LitElement {
   @property() label = "Setting";
   @property() description = "";
-  @property({ type: Array }) options: SelectOption[] = [];
+  @property() id = "setting-select-input";
+  @property({ type: Array }) options: SettingSelectOption[] = [];
   @property({ type: String }) value = "";
+  @property({ type: Boolean }) easter = false;
 
   createRenderRoot() {
     return this;
@@ -35,14 +37,18 @@ export class SettingSelect extends LitElement {
   }
 
   render() {
+    const rainbowClass = this.easter
+      ? "bg-[linear-gradient(270deg,#990033,#996600,#336600,#008080,#1c3f99,#5e0099,#990033)] bg-[length:1400%_1400%] animate-rainbow-bg text-white hover:bg-[linear-gradient(270deg,#990033,#996600,#336600,#008080,#1c3f99,#5e0099,#990033)]"
+      : "";
+
     return html`
       <div
-        class="flex flex-col w-full p-4 bg-white/5 border border-white/10 rounded-xl hover:bg-white/10 transition-all gap-3"
+        class="flex flex-col w-full p-4 bg-white/5 border border-white/10 rounded-xl hover:bg-white/10 transition-all gap-3 ${rainbowClass}"
       >
         <div class="flex flex-col min-w-0">
           <label
             class="text-white font-bold text-base block mb-1"
-            for="setting-select-input"
+            for=${this.id}
             >${this.label}</label
           >
           <div class="text-white/50 text-sm leading-snug">
@@ -51,7 +57,7 @@ export class SettingSelect extends LitElement {
         </div>
         <div class="relative w-full">
           <select
-            id="setting-select-input"
+            id=${this.id}
             class="w-full appearance-none py-2 pl-3 pr-9 border border-white/20 rounded-lg bg-black/40 text-white font-mono text-sm focus:outline-none focus:border-blue-500 focus:ring-1 focus:ring-blue-500 transition-all"
             .value=${String(this.value)}
             @change=${this.handleChange}
diff --git a/src/client/graphics/layers/SettingsModal.ts b/src/client/graphics/layers/SettingsModal.ts
index 5f747c6ba..c61cab390 100644
--- a/src/client/graphics/layers/SettingsModal.ts
+++ b/src/client/graphics/layers/SettingsModal.ts
@@ -149,6 +149,17 @@ export class SettingsModal extends LitElement implements Layer {
     this.requestUpdate();
   }
 
+  private onTerritoryBorderModeChange(event: Event) {
+    const value = (event.target as HTMLSelectElement).value;
+    const mode = Number.parseInt(value, 10);
+    if (!Number.isFinite(mode))
+      throw new Error(`Invalid border mode: ${value}`);
+
+    this.userSettings.setInt("settings.territoryBorderMode", mode);
+    this.eventBus.emit(new RefreshGraphicsEvent());
+    this.requestUpdate();
+  }
+
   private onToggleRandomNameModeButtonClick() {
     this.userSettings.toggleRandomName();
     this.requestUpdate();
@@ -299,6 +310,34 @@ export class SettingsModal extends LitElement implements Layer {
               </div>
             </button>
 
+            <div
+              class="flex gap-3 items-center w-full text-left p-3 hover:bg-slate-700 rounded-sm text-white transition-colors"
+            >
+              <img
+                src=${treeIcon}
+                alt="territoryBorderMode"
+                width="20"
+                height="20"
+              />
+              <div class="flex-1">
+                <div class="font-medium">
+                  ${translateText("user_setting.territory_border_mode_label")}
+                </div>
+                <div class="text-sm text-slate-400">
+                  ${translateText("user_setting.territory_border_mode_desc")}
+                </div>
+              </div>
+              <select
+                class="shrink-0 bg-slate-900 border border-slate-600 text-white/90 rounded px-2 py-1 focus:outline-none focus:ring-2 focus:ring-blue-600"
+                .value=${String(this.userSettings.territoryBorderMode())}
+                @change=${this.onTerritoryBorderModeChange}
+              >
+                <option value="0">Off</option>
+                <option value="1">Simple</option>
+                <option value="2">Glow</option>
+              </select>
+            </div>
+
             <button
               class="flex gap-3 items-center w-full text-left p-3 hover:bg-slate-700 rounded-sm text-white transition-colors"
               @click="${this.onToggleEmojisButtonClick}"
diff --git a/src/client/graphics/layers/TerritoryLayer.ts b/src/client/graphics/layers/TerritoryLayer.ts
index 632e96432..3a35080cb 100644
--- a/src/client/graphics/layers/TerritoryLayer.ts
+++ b/src/client/graphics/layers/TerritoryLayer.ts
@@ -27,6 +27,7 @@ export class TerritoryLayer implements Layer {
 
   private lastPaletteSignature: string | null = null;
   private lastDefensePostsSignature: string | null = null;
+  private lastBorderMode: number | null = null;
 
   private lastMousePosition: { x: number; y: number } | null = null;
   private hoveredOwnerSmallId: number | null = null;
@@ -68,6 +69,7 @@ export class TerritoryLayer implements Layer {
 
     this.refreshPaletteIfNeeded();
     this.refreshDefensePostsIfNeeded();
+    this.refreshBorderModeIfNeeded();
 
     const updatedTiles = this.game.recentlyUpdatedTiles();
     for (let i = 0; i < updatedTiles.length; i++) {
@@ -98,6 +100,8 @@ export class TerritoryLayer implements Layer {
     this.territoryRenderer = renderer;
     this.territoryRenderer.setAlternativeView(this.alternativeView);
     this.territoryRenderer.setHighlightedOwnerId(this.hoveredOwnerSmallId);
+    this.lastBorderMode = this.userSettings.territoryBorderMode();
+    this.territoryRenderer.setBorderMode(this.lastBorderMode);
     this.territoryRenderer.markAllDirty();
     this.territoryRenderer.refreshPalette();
     this.lastPaletteSignature = this.computePaletteSignature();
@@ -282,6 +286,17 @@ export class TerritoryLayer implements Layer {
     }
   }
 
+  private refreshBorderModeIfNeeded() {
+    if (!this.territoryRenderer) {
+      return;
+    }
+    const mode = this.userSettings.territoryBorderMode();
+    if (mode !== this.lastBorderMode) {
+      this.lastBorderMode = mode;
+      this.territoryRenderer.setBorderMode(mode);
+    }
+  }
+
   private computeDefensePostsSignature(): string {
     // Active + completed posts only.
     const parts: string[] = [];
diff --git a/src/client/graphics/webgpu/TerritoryRenderer.ts b/src/client/graphics/webgpu/TerritoryRenderer.ts
index 6b3116b99..85b1eb3b6 100644
--- a/src/client/graphics/webgpu/TerritoryRenderer.ts
+++ b/src/client/graphics/webgpu/TerritoryRenderer.ts
@@ -227,6 +227,13 @@ export class TerritoryRenderer {
     this.resources.setHighlightedOwnerId(ownerSmallId);
   }
 
+  setBorderMode(mode: number): void {
+    if (!this.resources) {
+      return;
+    }
+    this.resources.setBorderMode(mode);
+  }
+
   markTile(tile: TileRef): void {
     if (this.stateUpdatePass) {
       this.stateUpdatePass.markTile(tile);
diff --git a/src/client/graphics/webgpu/core/GroundTruthData.ts b/src/client/graphics/webgpu/core/GroundTruthData.ts
index d27a05bee..9bf5a1b73 100644
--- a/src/client/graphics/webgpu/core/GroundTruthData.ts
+++ b/src/client/graphics/webgpu/core/GroundTruthData.ts
@@ -78,6 +78,7 @@ export class GroundTruthData {
   private viewOffsetY = 0;
   private alternativeView = false;
   private highlightedOwnerId = -1;
+  private borderMode = 1;
 
   private constructor(
     private readonly device: GPUDevice,
@@ -223,6 +224,10 @@ export class GroundTruthData {
     this.highlightedOwnerId = ownerSmallId ?? -1;
   }
 
+  setBorderMode(mode: number): void {
+    this.borderMode = Math.max(0, Math.min(2, Math.trunc(mode)));
+  }
+
   // =====================
   // Upload methods
   // =====================
@@ -608,9 +613,11 @@ export class GroundTruthData {
   }
 
   private ensureDefensePostsByOwnerBuffer(capacityPosts: number): void {
+    const requested = Math.max(1, capacityPosts);
     if (
       this.defensePostsByOwnerBuffer &&
-      capacityPosts <= this.defensePostsByOwnerCapacity
+      requested <= this.defensePostsByOwnerCapacity &&
+      this.defensePostsByOwnerStaging
     ) {
       return;
     }
@@ -621,7 +628,7 @@ export class GroundTruthData {
 
     this.defensePostsByOwnerCapacity = Math.max(
       8,
-      Math.pow(2, Math.ceil(Math.log2(Math.max(1, capacityPosts)))),
+      Math.pow(2, Math.ceil(Math.log2(requested))),
     );
 
     const bytesPerPost = 8; // 2 * u32 (x,y)
@@ -846,7 +853,7 @@ export class GroundTruthData {
     this.uniformData[7] = this.highlightedOwnerId;
     this.uniformData[8] = this.viewWidth;
     this.uniformData[9] = this.viewHeight;
-    this.uniformData[10] = 0;
+    this.uniformData[10] = this.borderMode;
     this.uniformData[11] = 0;
 
     this.device.queue.writeBuffer(this.uniformBuffer, 0, this.uniformData);
diff --git a/src/client/graphics/webgpu/shaders/render/territory.wgsl b/src/client/graphics/webgpu/shaders/render/territory.wgsl
index 565dc00aa..5064c0481 100644
--- a/src/client/graphics/webgpu/shaders/render/territory.wgsl
+++ b/src/client/graphics/webgpu/shaders/render/territory.wgsl
@@ -1,7 +1,7 @@
 struct Uniforms {
   mapResolution_viewScale_time: vec4f, // x=mapW, y=mapH, z=viewScale, w=timeSec
   viewOffset_alt_highlight: vec4f,     // x=offX, y=offY, z=alternativeView, w=highlightOwnerId
-  viewSize_pad: vec4f,                // x=viewW, y=viewH, z/w unused
+  viewSize_pad: vec4f,                // x=viewW, y=viewH, z=borderMode, w unused
 };
 
 @group(0) @binding(0) var<uniform> u: Uniforms;
@@ -30,6 +30,7 @@ fn fsMain(@builtin(position) pos: vec4f) -> @location(0) vec4f {
   let altView = u.viewOffset_alt_highlight.z;
   let highlightId = u.viewOffset_alt_highlight.w;
   let viewSize = u.viewSize_pad.xy;
+  let borderMode = u.viewSize_pad.z;
 
   // WebGPU fragment position is top-left origin and at pixel centers (0.5, 1.5, ...).
   let viewCoord = vec2f(pos.x - 0.5, pos.y - 0.5);
@@ -76,6 +77,62 @@ fn fsMain(@builtin(position) pos: vec4f) -> @location(0) vec4f {
     outColor = terrain;
   }
 
+  // Borders (purely visual): render a stable-pixel-width line at ownership edges.
+  if (borderMode > 0.5 && altView <= 0.5 && owner != 0u) {
+    let fx = fract(mapCoord.x);
+    let fy = fract(mapCoord.y);
+
+    var dist = 1e9;
+
+    // Only border against other non-zero owners.
+    if (texCoord.x > 0) {
+      let o = textureLoad(stateTex, texCoord + vec2i(-1, 0), 0).x & 0xFFFu;
+      if (o != 0u && o != owner) {
+        dist = min(dist, fx);
+      }
+    }
+    if (texCoord.x + 1 < i32(mapRes.x)) {
+      let o = textureLoad(stateTex, texCoord + vec2i(1, 0), 0).x & 0xFFFu;
+      if (o != 0u && o != owner) {
+        dist = min(dist, 1.0 - fx);
+      }
+    }
+    if (texCoord.y > 0) {
+      let o = textureLoad(stateTex, texCoord + vec2i(0, -1), 0).x & 0xFFFu;
+      if (o != 0u && o != owner) {
+        dist = min(dist, fy);
+      }
+    }
+    if (texCoord.y + 1 < i32(mapRes.y)) {
+      let o = textureLoad(stateTex, texCoord + vec2i(0, 1), 0).x & 0xFFFu;
+      if (o != 0u && o != owner) {
+        dist = min(dist, 1.0 - fy);
+      }
+    }
+
+    if (dist < 1e8) {
+      let pxPerTile = max(viewScale, 0.001);
+      let aaTiles = 1.0 / pxPerTile;
+      let thicknessPx = select(1.0, 2.5, borderMode > 1.5);
+      let thicknessTiles = thicknessPx / pxPerTile;
+
+      let line = 1.0 - smoothstep(thicknessTiles, thicknessTiles + aaTiles, dist);
+      outColor = vec4f(
+        mix(outColor.rgb, vec3f(0.0, 0.0, 0.0), clamp(line * 0.9, 0.0, 0.9)),
+        outColor.a,
+      );
+
+      if (borderMode > 1.5) {
+        let glowTiles = (thicknessPx * 3.0) / pxPerTile;
+        let glow = 1.0 - smoothstep(glowTiles, glowTiles + aaTiles * 2.0, dist);
+        outColor = vec4f(
+          mix(outColor.rgb, vec3f(1.0, 1.0, 1.0), clamp(glow * 0.12, 0.0, 0.12)),
+          outColor.a,
+        );
+      }
+    }
+  }
+
   // Apply hover highlight if needed
   if (highlightId > 0.5) {
     let alpha = select(0.65, 0.0, altView > 0.5);
diff --git a/src/core/game/UserSettings.ts b/src/core/game/UserSettings.ts
index 5062c7936..44f7695b0 100644
--- a/src/core/game/UserSettings.ts
+++ b/src/core/game/UserSettings.ts
@@ -123,6 +123,20 @@ export class UserSettings {
     this.setCached(key, value.toString());
   }
 
+  getInt(key: string, defaultValue: number): number {
+    const value = localStorage.getItem(key);
+    if (!value) return defaultValue;
+
+    const intValue = parseInt(value, 10);
+    if (!Number.isFinite(intValue)) return defaultValue;
+
+    return intValue;
+  }
+
+  setInt(key: string, value: number): void {
+    localStorage.setItem(key, Math.trunc(value).toString());
+  }
+
   emojis() {
     return this.getBool("settings.emojis", true);
   }
@@ -174,6 +188,10 @@ export class UserSettings {
     );
   }
 
+  territoryBorderMode(): number {
+    return this.getInt("settings.territoryBorderMode", 1);
+  }
+
   cursorCostLabel() {
     const legacy = this.getBool("settings.ghostPricePill", true);
     return this.getBool("settings.cursorCostLabel", legacy);