diff --git a/editor/client/public/common/chunkterrain.js b/editor/client/public/common/chunkterrain.js
index aa1290f4..4a19360e 100644
--- a/editor/client/public/common/chunkterrain.js
+++ b/editor/client/public/common/chunkterrain.js
@@ -105,6 +105,46 @@ const ChunkTerrain = (() => {
     return new Float32Array(out);
   }
 
+  // Four edges (SW-SE, SE-NE, NE-NW, NW-SW) of a tile's quad as line
+  // segments, lifted slightly above the terrain surface to avoid
+  // z-fighting - same corner-height convention as pushTileQuad().
+  function pushTileGridLines(out, fx, fy, swZ, seZ, neZ, nwZ) {
+    const eps = 0.01;
+    const sw = [fx,     fy,     swZ + eps];
+    const se = [fx + 1, fy,     seZ + eps];
+    const ne = [fx + 1, fy + 1, neZ + eps];
+    const nw = [fx,     fy + 1, nwZ + eps];
+    const edges = [sw, se, se, ne, ne, nw, nw, sw];
+    for(const [x, y, z] of edges) out.push(0, 0, x, y, z);
+  }
+
+  // Generate grid-outline line segments for every non-null tile, following
+  // the same per-corner heights as buildTerrainVerts() so lines hug ramps
+  // instead of cutting through them. Returns a Float32Array of interleaved
+  // [u, v, x, y, z] vertices meant to be drawn with gl.LINES (pairs).
+  function buildGridLines(tiles) {
+    const out = [];
+    for(let z = 0; z < CHUNK_DEPTH; z++) {
+      for(let y = 0; y < CHUNK_HEIGHT; y++) {
+        for(let x = 0; x < CHUNK_WIDTH; x++) {
+          const type = tiles[tileIndex(x, y, z)] || TILE_SHAPE_NULL;
+          const corners = RAMP_CORNERS[type];
+          if(!corners) continue;
+
+          const [sw, se, ne, nw] = corners;
+          pushTileGridLines(
+            out, x, y,
+            (z + sw) * WORLD_LAYER_HEIGHT,
+            (z + se) * WORLD_LAYER_HEIGHT,
+            (z + ne) * WORLD_LAYER_HEIGHT,
+            (z + nw) * WORLD_LAYER_HEIGHT
+          );
+        }
+      }
+    }
+    return new Float32Array(out);
+  }
+
   return Object.freeze({
     CHUNK_WIDTH, CHUNK_HEIGHT, CHUNK_DEPTH, TILE_COUNT, WORLD_LAYER_HEIGHT,
     TILE_SHAPE_NULL, TILE_SHAPE_GROUND,
@@ -114,6 +154,6 @@ const ChunkTerrain = (() => {
     TILE_SHAPE_RAMP_SOUTHEAST, TILE_SHAPE_RAMP_SOUTHWEST,
     TILE_SHAPE_RAMP_NORTHEAST_INNER, TILE_SHAPE_RAMP_NORTHWEST_INNER,
     TILE_SHAPE_RAMP_SOUTHEAST_INNER, TILE_SHAPE_RAMP_SOUTHWEST_INNER,
-    RAMP_CORNERS, tileIndex, buildTerrainVerts,
+    RAMP_CORNERS, tileIndex, buildTerrainVerts, buildGridLines,
   });
 })();
diff --git a/editor/client/public/map/map.js b/editor/client/public/map/map.js
index a2202753..d5b2592f 100644
--- a/editor/client/public/map/map.js
+++ b/editor/client/public/map/map.js
@@ -146,6 +146,7 @@
 
   let mapRenderer = null;
   let terrainMesh = null;
+  let gridLinesMesh = null;
   let terrainTexturePromise = null;
   let modelIndex = null;
   let neighborChunks = [];
@@ -496,7 +497,7 @@
         const sy = (ChunkTerrain.CHUNK_HEIGHT - 1 - y) * cell;
         ctx.fillStyle = SHAPE_COLORS[type] || "#15171b";
         ctx.fillRect(x * cell, sy, cell, cell);
-        ctx.strokeStyle = "rgba(255, 255, 255, 0.08)";
+        ctx.strokeStyle = "rgba(255, 255, 255, 0.25)";
         ctx.strokeRect(x * cell, sy, cell, cell);
 
         const dir = SHAPE_DIRECTIONS[type];
@@ -599,6 +600,9 @@
   function rebuildTerrainMesh() {
     const floats = ChunkTerrain.buildTerrainVerts(tiles);
     terrainMesh = floats.length ? mapRenderer.createMesh(floats) : null;
+
+    const lineFloats = ChunkTerrain.buildGridLines(tiles);
+    gridLinesMesh = lineFloats.length ? mapRenderer.createMesh(lineFloats) : null;
   }
 
   // Keeps the preview canvas's backing-store resolution matched to its
@@ -649,6 +653,7 @@
       target: [ChunkTerrain.CHUNK_WIDTH / 2, ChunkTerrain.CHUNK_HEIGHT / 2, zLevelHeight],
       worldH: zoomWorldH,
       terrain: terrainMesh ? { mesh: terrainMesh, texture: terrainTexture } : null,
+      gridLines: gridLinesMesh ? { mesh: gridLinesMesh } : null,
       models,
       neighbors,
       highlight: hoverTile ? { x: hoverTile.x, y: hoverTile.y, z: zLevelHeight } : null,
diff --git a/editor/client/public/map/renderer.js b/editor/client/public/map/renderer.js
index 0c5976a7..fc9c7470 100644
--- a/editor/client/public/map/renderer.js
+++ b/editor/client/public/map/renderer.js
@@ -221,6 +221,7 @@ const MapRenderer = (() => {
     // scene = {
     //   target: [x, y, z], worldH: number,
     //   terrain: { mesh, texture } | null,
+    //   gridLines: { mesh } | null,
     //   models: [{ mesh, texture, color: [r,g,b,a in 0..1], offset: [x,y,z] }],
     //   neighbors: [{
     //     offset: [x,y,z],
@@ -248,6 +249,10 @@ const MapRenderer = (() => {
         drawMesh(scene.terrain.mesh, identity, scene.terrain.texture, [1, 1, 1, 1], true);
       }
 
+      if(scene.gridLines) {
+        drawMesh(scene.gridLines.mesh, identity, null, [0, 0, 0, 0.35], false, gl.LINES);
+      }
+
       for(const model of scene.models) {
         const modelMatrix = mat4Translation(new Float32Array(16), model.offset);
         drawMesh(model.mesh, modelMatrix, model.texture, model.color, true);