diff --git a/core/src/Portal.cpp b/core/src/Portal.cpp
index 6b361c4..228b803 100644
--- a/core/src/Portal.cpp
+++ b/core/src/Portal.cpp
@@ -315,3 +315,149 @@ int PortalNetwork::buildPortalNear(DimensionId dimension, const Vec3i& target) {
     bool natural = transit.findSafeSpot(dimension, target, radius, frame.height + 1, spot);
     if (!natural) spot = {target.x, cfg.clampY(target.y), target.z};
 
+    if (spot.y - 1 < cfg.floorY || spot.y + frame.height >= cfg.ceilingY - 1) return -1;
+
+    frame.origin = spot;
+    if (!natural || !PortalScan::siteUsable(destination.world(), frame)) {
+        transit.carvePlatform(dimension, spot, 3, frame.height + 2);
+        if (!PortalScan::siteUsable(destination.world(), frame)) return -1;
+    }
+
+    PortalScan::buildFrame(destination.world(), frame);
+    if (PortalScan::light(destination.world(), frame) == 0) return -1;
+    return registerPortal(dimension, frame);
+}
+
+PortalSearch PortalNetwork::travel(int entityId, int sourcePortalId, DimensionId to) {
+    PortalSearch search;
+    const PortalLink* source = portal(sourcePortalId);
+    if (!source || !source->active) return search;
+    if (!readyToTravel(entityId)) {
+        search.blocked = true;
+        return search;
+    }
+
+    DimensionId from = source->dimension;
+    Vec3i position = source->frame.entry();
+
+    std::vector<Vec3i> candidates;
+    std::vector<int> candidateIds;
+    for (const PortalLink& link : portals) {
+        if (!link.active || link.dimension != to) continue;
+        candidates.push_back(link.frame.entry());
+        candidateIds.push_back(link.id);
+    }
+
+    search.plan = transit.plan(from, to, position, candidates);
+
+    if (!search.plan.needsPortal) {
+        std::size_t index = static_cast<std::size_t>(search.plan.nearestIndex);
+        search.found = true;
+        search.portalId = candidateIds[index];
+        search.position = candidates[index];
+        search.distanceSquared = search.plan.nearestDistanceSquared;
+    } else {
+        int raised = buildPortalNear(to, search.plan.target);
+        if (raised < 0) return search;
+        search.found = true;
+        search.built = true;
+        search.portalId = raised;
+        search.position = portals[static_cast<std::size_t>(raised)].frame.entry();
+    }
+
+    linkPortals(sourcePortalId, search.portalId);
+    startCooldown(entityId);
+    return search;
+}
+
+void PortalNetwork::tickEntity(int entityId, bool insidePortal) {
+    int& remaining = cooldown[entityId];
+    int& charged = standing[entityId];
+
+    if (remaining > 0) {
+        --remaining;
+        charged = 0;
+        return;
+    }
+    if (insidePortal) ++charged;
+    else charged = 0;
+}
+
+int PortalNetwork::standingTicks(int entityId) const {
+    auto it = standing.find(entityId);
+    return it == standing.end() ? 0 : it->second;
+}
+
+int PortalNetwork::cooldownTicks(int entityId) const {
+    auto it = cooldown.find(entityId);
+    return it == cooldown.end() ? 0 : it->second;
+}
+
+bool PortalNetwork::readyToTravel(int entityId) const {
+    return cooldownTicks(entityId) == 0 && standingTicks(entityId) >= standingThreshold;
+}
+
+void PortalNetwork::startCooldown(int entityId) {
+    cooldown[entityId] = cooldownAfterTravel;
+    standing[entityId] = 0;
+}
+
+int PortalNetwork::buildEndFrame(DimensionId dimension, const Vec3i& center) {
+    World& world = dimensions().dimension(dimension).world();
+    int placed = 0;
+
+    for (const Vec3i& offset : endRingOffsets) {
+        Vec3i slot = center + offset;
+        world.setBlock(slot.x, slot.y, slot.z, Block::EndPortalFrame);
+        ++placed;
+    }
+    for (int dx = -1; dx <= 1; ++dx)
+        for (int dz = -1; dz <= 1; ++dz)
+            world.setBlock(center.x + dx, center.y, center.z + dz, Block::Air);
+    return placed;
+}
+
+bool PortalNetwork::hasEndEye(DimensionId dimension, const Vec3i& framePos) const {
+    const auto& sockets = eyes[dimensionIndex(dimension)];
+    return sockets.find(framePos) != sockets.end();
+}
+
+bool PortalNetwork::insertEndEye(DimensionId dimension, const Vec3i& framePos) {
+    World& world = dimensions().dimension(dimension).world();
+    if (world.blockAt(framePos.x, framePos.y, framePos.z) != Block::EndPortalFrame) return false;
+    if (!eyes[dimensionIndex(dimension)].insert(framePos).second) return false;
+
+    for (const Vec3i& offset : endRingOffsets) {
+        Vec3i center{framePos.x - offset.x, framePos.y - offset.y, framePos.z - offset.z};
+        activateEndPortal(dimension, center);
+    }
+    return true;
+}
+
+int PortalNetwork::endEyeCount(DimensionId dimension, const Vec3i& center) const {
+    const World& world = dimensions().dimension(dimension).world();
+    int filled = 0;
+
+    for (const Vec3i& offset : endRingOffsets) {
+        Vec3i slot = center + offset;
+        if (world.blockAt(slot.x, slot.y, slot.z) != Block::EndPortalFrame) continue;
+        if (hasEndEye(dimension, slot)) ++filled;
+    }
+    return filled;
+}
+
+bool PortalNetwork::endFrameComplete(DimensionId dimension, const Vec3i& center) const {
+    return endEyeCount(dimension, center) == endFrameSlots;
+}
+
+bool PortalNetwork::activateEndPortal(DimensionId dimension, const Vec3i& center) {
+    if (!endFrameComplete(dimension, center)) return false;
+
+    World& world = dimensions().dimension(dimension).world();
+    for (int dx = -1; dx <= 1; ++dx)
+        for (int dz = -1; dz <= 1; ++dz)
+            world.setBlock(center.x + dx, center.y, center.z + dz, Block::EndPortal);
+    return true;
+}
+
+} // namespace vf