diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..87b189a
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,17 @@
+# Slimepire Project — Agent Rules
+
+## Before editing ANY file: ALWAYS re-read it first
+
+I often edit code manually while the agent is running. If you edit a file based on
+stale content from a previous read, you will overwrite my manual changes.
+
+**Rule:** Before calling `edit` or `write` on any existing file, read it again with
+`read` to get the current state. Never rely on file contents from earlier turns or
+from a previous compaction/context window.
+
+## Code style
+
+- Godot 4.7 C# project targeting .NET 10.0
+- Uses `GodotSharp.SourceGenerators` — provides `[Singleton]`, `[SceneTree]`,
+  `[ResourceTree]`, and `Instantiator.Instantiate<T>()`
+- Keep things simple, avoid over-engineering
diff --git a/src/Gameplay/BuildGhost.cs b/src/Gameplay/BuildGhost.cs
index 726ca46..3baf22b 100644
--- a/src/Gameplay/BuildGhost.cs
+++ b/src/Gameplay/BuildGhost.cs
@@ -87,7 +87,10 @@ public partial class BuildGhost : Node2D
             {
                 var nodule = NoduleScene.Instantiate<Nodule>();
                 nodule.Position = Position;
+                nodule.EnergyBuildCost = 5f; // TODO: make configurable per nodule type
+                nodule.ConstructionProgress = 0;
                 GetParent()?.AddChild(nodule);
+                NoduleManager.Instance.RequestConstruction(nodule);
                 CleanupBuildMode();
             }
         }
diff --git a/src/Gameplay/Components/Energy/EnergyPackage.cs b/src/Gameplay/Components/Energy/EnergyPackage.cs
new file mode 100644
index 0000000..cf51a80
--- /dev/null
+++ b/src/Gameplay/Components/Energy/EnergyPackage.cs
@@ -0,0 +1,49 @@
+using Godot;
+
+namespace Slimepire.Gameplay.Components;
+
+[SceneTree]
+public partial class EnergyPackage : Node2D
+{
+    [Export]
+    public float TravelSpeed { get; set; } = 200f;
+
+    private Vector2[] _waypoints = [];
+    private int _currentWaypointIndex;
+
+    public event Action? Arrived;
+
+    public void SetWaypoints(Vector2[] waypoints)
+    {
+        _waypoints = waypoints;
+        if (_waypoints.Length > 0)
+        {
+            GlobalPosition = _waypoints[0];
+        }
+    }
+
+    public override void _Process(double delta)
+    {
+        if (_waypoints.Length == 0 || _currentWaypointIndex >= _waypoints.Length - 1)
+        {
+            Arrived?.Invoke();
+            QueueFree();
+            return;
+        }
+
+        var target = _waypoints[_currentWaypointIndex + 1];
+        var direction = target - GlobalPosition;
+        var distance = direction.Length();
+        var step = TravelSpeed * (float)delta;
+
+        if (step >= distance)
+        {
+            GlobalPosition = target;
+            _currentWaypointIndex++;
+        }
+        else
+        {
+            GlobalPosition += direction.Normalized() * step;
+        }
+    }
+}
diff --git a/src/Gameplay/Components/Energy/EnergyPackage.cs.uid b/src/Gameplay/Components/Energy/EnergyPackage.cs.uid
new file mode 100644
index 0000000..3f97dd7
--- /dev/null
+++ b/src/Gameplay/Components/Energy/EnergyPackage.cs.uid
@@ -0,0 +1 @@
+uid://nk5tjlmcrpn2
diff --git a/src/Gameplay/Components/Energy/EnergyPackage.tscn b/src/Gameplay/Components/Energy/EnergyPackage.tscn
new file mode 100644
index 0000000..c18eb90
--- /dev/null
+++ b/src/Gameplay/Components/Energy/EnergyPackage.tscn
@@ -0,0 +1,29 @@
+[gd_scene format=3 uid="uid://dwdbqktsl34sm"]
+
+[ext_resource type="Script" uid="uid://nk5tjlmcrpn2" path="res://src/Gameplay/Components/Energy/EnergyPackage.cs" id="1_kmtmh"]
+[ext_resource type="Texture2D" uid="uid://bjl6gqj0bvhhp" path="res://assets/energy_package.png" id="2_psum7"]
+
+[sub_resource type="Curve" id="Curve_psum7"]
+_data = [Vector2(0, 1), 0.0, 0.0, 0, 0, Vector2(1e-05, 1), 0.0, 0.0, 0, 0, Vector2(1, 0), 0.0, 0.0, 0, 0]
+point_count = 3
+
+[sub_resource type="CurveTexture" id="CurveTexture_psum7"]
+curve = SubResource("Curve_psum7")
+
+[sub_resource type="ParticleProcessMaterial" id="ParticleProcessMaterial_psum7"]
+particle_flag_disable_z = true
+inherit_velocity_ratio = 0.625
+gravity = Vector3(0, 10, 0)
+scale_curve = SubResource("CurveTexture_psum7")
+
+[node name="EnergyPackage" type="Node2D" unique_id=869544034]
+z_index = 2
+script = ExtResource("1_kmtmh")
+
+[node name="GPUParticles2D" type="GPUParticles2D" parent="." unique_id=388560926]
+modulate = Color(1, 0.7764706, 0, 1)
+texture = ExtResource("2_psum7")
+lifetime = 0.3
+use_fixed_seed = true
+seed = 874795105
+process_material = SubResource("ParticleProcessMaterial_psum7")
diff --git a/src/Gameplay/Components/Energy/EnergyStorage.cs b/src/Gameplay/Components/Energy/EnergyStorage.cs
index 67ba8e9..c9fdd2c 100644
--- a/src/Gameplay/Components/Energy/EnergyStorage.cs
+++ b/src/Gameplay/Components/Energy/EnergyStorage.cs
@@ -16,20 +16,22 @@ public partial class EnergyStorage : Node
         get;
         set
         {
-            if (field + value > MaxEnergy)
-            {
-                field = MaxEnergy;
-            }
-            else
-            {
-                field += value;
-            }
-
-            field = value;
+            field = Mathf.Clamp(field + value, 0, MaxEnergy);
             UpdateLabel();
         }
     }
 
+    public bool TryConsume(float amount)
+    {
+        if (Energy >= amount)
+        {
+            Energy = -amount;
+            return true;
+        }
+
+        return false;
+    }
+
     public override void _Ready()
     {
         UpdateLabel();
diff --git a/src/Gameplay/NoduleManager.cs b/src/Gameplay/NoduleManager.cs
index 110f809..bebea10 100644
--- a/src/Gameplay/NoduleManager.cs
+++ b/src/Gameplay/NoduleManager.cs
@@ -1,4 +1,5 @@
 using Godot;
+using Slimepire.Gameplay.Components;
 using Slimepire.Gameplay.Nodules;
 
 namespace Slimepire.Gameplay;
@@ -6,11 +7,16 @@ namespace Slimepire.Gameplay;
 [Singleton]
 public partial class NoduleManager
 {
+    private const float PackageSendInterval = 0.3f;
+    private const float ConstructionRetryInterval = 2f;
+
     public bool Building { get; set; }
 
     private AStar2D _aStar = new();
     private readonly Dictionary<long, Nodule> _nodules = [];
     private readonly HashSet<NoduleConnection> _connections = [];
+    private readonly List<RootNodule> _rootNodules = [];
+    private readonly Dictionary<long, ConstructionRequest> _activeConstructions = [];
 
     // GFX
     private readonly Dictionary<NoduleConnection, Tube> _tubeConnections = new();
@@ -20,6 +26,11 @@ public partial class NoduleManager
         _nodules.Add(nodule.NoduleId, nodule);
         _aStar.AddPoint(nodule.NoduleId, nodule.Position);
 
+        if (nodule is RootNodule root && !_rootNodules.Contains(root))
+        {
+            _rootNodules.Add(root);
+        }
+
         UpdateNoduleConnections();
         UpdateTubesAndAstar();
     }
@@ -30,6 +41,176 @@ public partial class NoduleManager
         UpdateTubesAndAstar();
     }
 
+    public void OnNoduleConstructed(Nodule nodule)
+    {
+        // Add all AStar connections that were skipped during construction
+        foreach (var neighbor in nodule.Connections)
+        {
+            _aStar.ConnectPoints(nodule.NoduleId, neighbor.NoduleId);
+        }
+
+        // Convert any ghost tubes connected to this nodule to real tubes.
+        // Tubes are not always children of this nodule (depends on hash ordering in NoduleConnection),
+        // so iterating children alone isn't enough.
+        foreach (var (conn, tube) in _tubeConnections)
+        {
+            if (tube.IsGhost && (ReferenceEquals(conn.A, nodule) || ReferenceEquals(conn.B, nodule)))
+            {
+                tube.SetGhost(false);
+            }
+        }
+    }
+
+    public void RequestConstruction(Nodule target)
+    {
+        if (!target.IsConstructing)
+            return;
+
+        // Defer to allow connections to be established (physics frame overlap detection)
+        var tree = target.GetTree();
+        tree.CreateTimer(0.1f).Timeout += () => TryStartConstruction(target);
+    }
+
+    private void TryStartConstruction(Nodule target)
+    {
+        // Constructing nodule has no AStar connections yet — route via neighbors
+        var (sourceRoot, waypoints) = FindPathViaNeighbors(target);
+        if (sourceRoot == null || waypoints.Length == 0)
+        {
+            // No path yet — retry periodically until a RootNodule becomes reachable
+            // TODO: ist das hier richtig?
+            var tree = target.GetTree();
+            tree.CreateTimer(ConstructionRetryInterval).Timeout += () =>
+            {
+                if (target.IsConstructing && !_activeConstructions.ContainsKey(target.NoduleId))
+                    TryStartConstruction(target);
+            };
+            return;
+        }
+
+        var request = new ConstructionRequest
+        {
+            Target = target,
+            SourceRoot = sourceRoot,
+            Waypoints = waypoints,
+        };
+
+        _activeConstructions[target.NoduleId] = request;
+        SendNextPackage(request);
+    }
+
+    private void SendNextPackage(ConstructionRequest request)
+    {
+        var target = request.Target;
+
+        if (!target.IsConstructing)
+        {
+            _activeConstructions.Remove(target.NoduleId);
+            return;
+        }
+
+        var energyStorage = request.SourceRoot.GetNode<EnergyStorage>("EnergyStorage");
+        if (energyStorage == null || !energyStorage.TryConsume(1))
+        {
+            // Source empty — retry after a delay
+            var tree = request.SourceRoot.GetTree();
+            tree.CreateTimer(PackageSendInterval).Timeout += () =>
+            {
+                if (_activeConstructions.ContainsKey(target.NoduleId))
+                    SendNextPackage(request);
+            };
+            return;
+        }
+
+        var package = Instantiator.Instantiate<EnergyPackage>();
+        package.SetWaypoints(request.Waypoints);
+
+        // Add to tree as sibling of source root so it's visible
+        var parent = request.SourceRoot.GetParent();
+        parent?.AddChild(package);
+        package.GlobalPosition = request.Waypoints[0];
+
+        package.Arrived += () =>
+        {
+            target.ReceiveConstructionEnergy(1);
+
+            if (!target.IsConstructing)
+            {
+                _activeConstructions.Remove(target.NoduleId);
+                return;
+            }
+
+            // Send next package after a short interval
+            var tree = target.GetTree();
+            tree.CreateTimer(PackageSendInterval).Timeout += () =>
+            {
+                if (_activeConstructions.TryGetValue(target.NoduleId, out var req))
+                    SendNextPackage(req);
+            };
+        };
+    }
+
+    private (RootNodule? source, Vector2[] waypoints) FindPathViaNeighbors(Nodule target)
+    {
+        RootNodule? bestRoot = null;
+        Vector2[] bestWaypoints = [];
+        float bestDist = float.MaxValue;
+
+        foreach (var neighbor in target.Connections)
+        {
+            foreach (var root in _rootNodules)
+            {
+                var pointPath = _aStar.GetPointPath(root.NoduleId, neighbor.NoduleId);
+                if (pointPath.Length == 0)
+                    continue;
+
+                var dist = 0f;
+                for (var i = 0; i < pointPath.Length - 1; i++)
+                    dist += pointPath[i].DistanceTo(pointPath[i + 1]);
+                dist += pointPath[^1].DistanceTo(target.GlobalPosition);
+
+                if (dist < bestDist)
+                {
+                    bestDist = dist;
+                    bestRoot = root;
+                    bestWaypoints = [.. pointPath, target.GlobalPosition];
+                }
+            }
+        }
+
+        return (bestRoot, bestWaypoints);
+    }
+
+    private (RootNodule? source, long[] path) FindNearestRootNodule(Nodule target)
+    {
+        RootNodule? nearest = null;
+        float shortestDist = float.MaxValue;
+        long[] shortestIds = [];
+
+        foreach (var root in _rootNodules)
+        {
+            var ids = _aStar.GetIdPath(root.NoduleId, target.NoduleId);
+            if (ids.Length == 0)
+                continue;
+
+            var path = _aStar.GetPointPath(root.NoduleId, target.NoduleId);
+            var dist = 0f;
+            for (var i = 0; i < path.Length - 1; i++)
+            {
+                dist += path[i].DistanceTo(path[i + 1]);
+            }
+
+            if (dist < shortestDist)
+            {
+                shortestDist = dist;
+                nearest = root;
+                shortestIds = [.. ids];
+            }
+        }
+
+        return (nearest, shortestIds);
+    }
+
     private void UpdateNoduleConnections()
     {
         foreach (var nodule in _nodules.Values)
@@ -53,7 +234,16 @@ public partial class NoduleManager
                 conn.A.AddChild(tube);
                 tube.SetTarget(conn.B.GlobalPosition);
 
-                _aStar.ConnectPoints(conn.A.NoduleId, conn.B.NoduleId);
+                // Ghost tubes for constructing nodules — visual only, no AStar
+                var eitherConstructing = conn.A.IsConstructing || conn.B.IsConstructing;
+                if (eitherConstructing)
+                {
+                    tube.SetGhost(true);
+                }
+                else
+                {
+                    _aStar.ConnectPoints(conn.A.NoduleId, conn.B.NoduleId);
+                }
             }
         }
     }
@@ -89,4 +279,11 @@ public partial class NoduleManager
             return HashCode.Combine(A, B);
         }
     }
+
+    private class ConstructionRequest
+    {
+        public required Nodule Target { get; init; }
+        public required RootNodule SourceRoot { get; init; }
+        public required Vector2[] Waypoints { get; init; }
+    }
 }
diff --git a/src/Gameplay/Nodules/Nodule.cs b/src/Gameplay/Nodules/Nodule.cs
index ed95375..a8e5f9d 100644
--- a/src/Gameplay/Nodules/Nodule.cs
+++ b/src/Gameplay/Nodules/Nodule.cs
@@ -11,17 +11,19 @@ public partial class Nodule : Node2D
     [Export]
     private AnimatedSprite2D _gfx = null!;
 
+    [Export]
+    public float EnergyBuildCost { get; set; } = 0f;
+
+    public float ConstructionProgress { get; set; }
+
+    public bool IsConstructing => EnergyBuildCost > 0 && ConstructionProgress < EnergyBuildCost;
+
     public List<Nodule> Connections { get; } = [];
 
     protected AnimatedSprite2D Gfx => _gfx;
 
     public long NoduleId => (long)GetInstanceId();
 
-    public void AttachTube(Tube tube)
-    {
-        AddChild(tube);
-    }
-
     public override void _Ready()
     {
         _tubeConnectionArea.AreaEntered += OnAreaEntered;
@@ -32,7 +34,15 @@ public partial class Nodule : Node2D
 
         // render above tubes
         ZIndex = 1;
-        _gfx.Play();
+
+        if (IsConstructing)
+        {
+            _gfx.Modulate = new Color(1, 1, 1, 0.4f);
+        }
+        else
+        {
+            _gfx.Play();
+        }
     }
 
     private void OnAreaEntered(Area2D area)
@@ -57,4 +67,25 @@ public partial class Nodule : Node2D
     {
         _gfx.SelfModulate = Colors.DarkOliveGreen;
     }
+
+    public void ReceiveConstructionEnergy(float amount)
+    {
+        if (!IsConstructing)
+            return;
+
+        ConstructionProgress = Mathf.Min(ConstructionProgress + amount, EnergyBuildCost);
+
+        if (ConstructionProgress >= EnergyBuildCost)
+        {
+            OnConstructionComplete();
+        }
+    }
+
+    protected virtual void OnConstructionComplete()
+    {
+        _gfx.Modulate = Colors.White;
+        _gfx.Play();
+
+        NoduleManager.Instance.OnNoduleConstructed(this);
+    }
 }
diff --git a/src/Gameplay/Tube.cs b/src/Gameplay/Tube.cs
index 5c75208..1555d1f 100644
--- a/src/Gameplay/Tube.cs
+++ b/src/Gameplay/Tube.cs
@@ -40,6 +40,17 @@ public partial class Tube : Node2D
         GenerateTube();
     }
 
+    private bool _isGhost;
+    public bool IsGhost => _isGhost;
+
+    public void SetGhost(bool ghost)
+    {
+        _isGhost = ghost;
+        Line2D.DefaultColor = ghost
+            ? new Color(0.3f, 0.49f, 0.24f, 0.3f)
+            : new Color(0.30588236f, 0.4862745f, 0.23921569f, 1f);
+    }
+
     public override void _Ready()
     {
         Line2D.Points = [];