diff --git a/core/src/Dimension.cpp b/core/src/Dimension.cpp
index 5f88a0e..4d5e0b9 100644
--- a/core/src/Dimension.cpp
+++ b/core/src/Dimension.cpp
@@ -150,3 +150,150 @@ int Dimension::highestSolidY(int gx, int gz) const {
     return cfg.floorY - 1;
 }
 
+bool Dimension::standingSpot(int gx, int gz, int fromY, int clearance, int& outFeetY) const {
+    int start = std::max(fromY, cfg.floorY);
+    for (int y = start; y < cfg.highestPlaceableY() - clearance; ++y) {
+        if (!blocks.solidAt(gx, y, gz)) continue;
+        bool roomy = true;
+        for (int up = 1; up <= clearance && roomy; ++up)
+            roomy = blocks.blockAt(gx, y + up, gz) == Block::Air;
+        if (!roomy) continue;
+        outFeetY = y + 1;
+        return true;
+    }
+    return false;
+}
+
+DimensionSet::DimensionSet(uint32_t worldSeed) : baseSeed(worldSeed) {
+    worlds.reserve(dimensionCount);
+    for (int index = 0; index < dimensionCount; ++index) {
+        DimensionId id = static_cast<DimensionId>(index);
+        worlds.push_back(std::make_unique<Dimension>(DimensionConfig::forDimension(id), worldSeed));
+    }
+}
+
+void DimensionSet::tickAll(int steps) {
+    for (auto& dimension : worlds) dimension->tick(steps);
+}
+
+std::size_t DimensionSet::totalChunks() const {
+    std::size_t total = 0;
+    for (const auto& dimension : worlds) total += dimension->world().chunkCount();
+    return total;
+}
+
+Vec3i DimensionTravel::scale(const Vec3i& pos, const DimensionConfig& from,
+                             const DimensionConfig& to) {
+    double ratio = static_cast<double>(from.coordinateScale) /
+                   static_cast<double>(to.coordinateScale);
+    return {static_cast<int>(std::floor(pos.x * ratio)), pos.y,
+            static_cast<int>(std::floor(pos.z * ratio))};
+}
+
+int DimensionTravel::searchRadiusFor(DimensionId to) {
+    return to == DimensionId::Nether ? 128 : 16;
+}
+
+int DimensionTravel::buildRadiusFor(DimensionId to) {
+    return std::min(searchRadiusFor(to), 16);
+}
+
+TravelResult DimensionTravel::plan(DimensionId from, DimensionId to, const Vec3i& pos) const {
+    return plan(from, to, pos, {});
+}
+
+TravelResult DimensionTravel::plan(DimensionId from, DimensionId to, const Vec3i& pos,
+                                   const std::vector<Vec3i>& knownPortals) const {
+    TravelResult result;
+    result.from = from;
+    result.to = to;
+    result.source = pos;
+
+    const DimensionConfig& origin = worlds.dimension(from).config();
+    const DimensionConfig& destination = worlds.dimension(to).config();
+
+    result.scaledTarget = scale(pos, origin, destination);
+    result.target = result.scaledTarget;
+    if (result.target.y < destination.lowestPlaceableY()) {
+        result.target.y = destination.lowestPlaceableY();
+        result.clampedToFloor = true;
+    } else if (result.target.y > destination.highestPlaceableY()) {
+        result.target.y = destination.highestPlaceableY();
+        result.clampedToCeiling = true;
+    }
+
+    result.searchRadius = searchRadiusFor(to);
+    long long best = -1;
+    for (std::size_t index = 0; index < knownPortals.size(); ++index) {
+        const Vec3i& candidate = knownPortals[index];
+        long long dx = candidate.x - result.target.x;
+        long long dy = candidate.y - result.target.y;
+        long long dz = candidate.z - result.target.z;
+        if (std::llabs(dx) > result.searchRadius || std::llabs(dz) > result.searchRadius) continue;
+        long long distance = dx * dx + dy * dy + dz * dz;
+        if (best >= 0 && distance >= best) continue;
+        best = distance;
+        result.nearestIndex = static_cast<int>(index);
+    }
+
+    if (result.nearestIndex >= 0) {
+        result.needsPortal = false;
+        result.nearestDistanceSquared = static_cast<int>(best);
+    }
+    return result;
+}
+
+bool DimensionTravel::findSafeSpot(DimensionId to, const Vec3i& near, int radius, int clearance,
+                                   Vec3i& outSpot) const {
+    const Dimension& destination = worlds.dimension(to);
+    int floorY = destination.config().floorY;
+
+    for (int ring = 0; ring <= radius; ++ring) {
+        int bestDrop = -1;
+        Vec3i best;
+        for (int dx = -ring; dx <= ring; ++dx) {
+            for (int dz = -ring; dz <= ring; ++dz) {
+                if (std::max(std::abs(dx), std::abs(dz)) != ring) continue;
+
+                int gx = near.x + dx;
+                int gz = near.z + dz;
+                int scan = floorY;
+                int feetY = 0;
+                while (destination.standingSpot(gx, gz, scan, clearance, feetY)) {
+                    int drop = std::abs(feetY - near.y);
+                    if (drop <= safeSpotVerticalBand && (bestDrop < 0 || drop < bestDrop)) {
+                        bestDrop = drop;
+                        best = {gx, feetY, gz};
+                    }
+                    scan = feetY + 1;
+                }
+            }
+        }
+        if (bestDrop >= 0) {
+            outSpot = best;
+            return true;
+        }
+    }
+    return false;
+}
+
+void DimensionTravel::carvePlatform(DimensionId to, const Vec3i& spot, int halfWidth,
+                                    int clearance) {
+    Dimension& destination = worlds.dimension(to);
+    const DimensionConfig& cfg = destination.config();
+    World& world = destination.world();
+
+    int deck = std::max(spot.y - 1, cfg.floorY);
+    for (int dx = -halfWidth; dx <= halfWidth; ++dx) {
+        for (int dz = -halfWidth; dz <= halfWidth; ++dz) {
+            world.setBlock(spot.x + dx, deck, spot.z + dz, Block::Obsidian);
+            for (int up = 1; up <= clearance; ++up) {
+                int y = deck + up;
+                if (y >= cfg.ceilingY - 1) break;
+                world.setBlock(spot.x + dx, y, spot.z + dz, Block::Air);
+            }
+        }
+    }
+}
+
+} // namespace vf