Simulation bridge

AGENTS.md

@@ -1,5 +1,6 @@
 # Platform and documentation
 
+Find out which platform you're running on.
 If this is a linux environment, read `AGENTS.linux.md`.
 If this is a windows environment, read `AGENTS.windows.md`.
 Follow the guidelines laid out in `CODESTYLE.md`.

TASKS.md

@@ -1,87 +1,4 @@
-# Reactor Maintenance Rewrite Tasks
-
-## Current State
-- Approved design iteration targets the simulation model, rule removal, action economy, reactor requirements, and editor layer workflow.
-- Work is proceeding on branch `design-iteration-structural-editor` in methodical commits.
-- Completed commits:
-  - `787f1e5` Document approved design iteration.
-  - `3d40617` Restore complete design system documentation.
-  - `e1ac56d` Rework simulation rules.
-- Design documentation must preserve every existing system-level rule unless a change explicitly supersedes it. Superseded sections must document the replacement behavior with equal detail.
-- The next implementation iteration is the Win2D editor overhaul.
-
-## Completed Work
-- Created the approved implementation plan for:
-  - single multi-service consumers,
-  - count-based reactor requirements,
-  - cell-derived doors,
-  - 0-10 structural integrity,
-  - fixed automatic rule systems,
-  - quick/lengthy action economy,
-  - all-seeing-eye viewing without persistent unlocking,
-  - layer-aware editor visualization and tools.
-- Repaired the design documentation after the hazard-interaction regression:
-  - restored the complete surface hazard interaction matrix,
-  - documented that leaked coolant plus leaked fuel directly holds unless mediated by heat/electricity,
-  - expanded structural integrity, consumer, reactor, all-seeing-eye, and action-economy details.
-- Reworked simulation state and systems:
-  - removed data-driven rule predicates/effects/events from runtime state, validation, forecasts, serialization, and tests,
-  - replaced explicit reactor consumer bindings with unbound reactor controls plus required fuel/coolant/electricity consumer counts,
-  - made consumer props carrier-agnostic with per-carrier service state derived from networks beneath the cell,
-  - moved doors from explicit edge state to door props on floor cells with orientation inferred from opposing wall cells,
-  - added underground structural integrity, high-pressure degradation, automatic leak creation, structural forecasts, and repair-to-max behavior,
-  - removed action budgets and made movement quick while mutating interactions resolve one simulation step,
-  - removed persistent all-seeing-eye unlocking from simulation state,
-  - bumped serialized level schema to version 3.
-- Updated simulation tests for the replacement systems:
-  - consumer derivation and disabled consumer service state,
-  - count-based reactor readiness and reactor-under-network positive-flow requirement,
-  - quick movement versus lengthy door interaction,
-  - inferred door blocking,
-  - structural degradation, automatic leaks, repair integrity reset,
-  - schema version 3 round-tripping and old-schema rejection.
-- Kept the Win2D project compiling after the simulation model changes with narrow compatibility edits. Full editor workflow/rendering work remains outstanding.
-- Verified after the simulation rework:
-  - `dotnet test tests\ReactorMaintenance.Simulation.Tests\ReactorMaintenance.Simulation.Tests.csproj` passed with 23 tests,
-  - `dotnet build ReactorMaintenance.slnx` passed with 0 warnings.
-- Reworked the Win2D editor workflow:
-  - added the Surface/Electricity/Fuel/Coolant layer combobox,
-  - filtered tools by active layer and fixed exclusive tool selection,
-  - rendered underground networks as carrier-colored centerline networks with source dots and layer opacity rules,
-  - removed Rule Events, Reactor Binding, and pending workflow panels from the editor UI,
-  - replaced two-click electricity leak authoring with electric-layer leak access cycling,
-  - made Shift+left drag pan in all tools and Cursor drag move the robot or props.
-- Added editor-helper tests for electricity leak access cycling and cursor drag movement behavior.
-- Verified after the editor overhaul:
-  - `dotnet test tests\ReactorMaintenance.Simulation.Tests\ReactorMaintenance.Simulation.Tests.csproj` passed with 26 tests,
-  - `dotnet build ReactorMaintenance.slnx` passed with 0 warnings.
-
-## Current Work
-- Editor overhaul implementation is complete; commit is pending.
-
-## Editor Overhaul Requirements
-- Add a layer combobox with Surface, Electricity, Fuel, and Coolant.
-- When Surface is active, draw the surface layer at full opacity and all underground layers at 25% opacity.
-- When an underground layer is active, draw the surface layer at 50% opacity, other underground layers at 25% opacity, and the active underground layer at full opacity.
-- Render coolant blue, fuel red, and electricity yellow.
-- Render networks as thick lines connecting adjacent cell centers; render sources as large centered dots.
-- Make tools layer-aware:
-  - Cursor is always available.
-  - Heat, Floor, Walls, Props, Consumers, Hazards, and Doors are only available for Surface.
-  - Network painting and Sources are only available on their respective underground layers.
-- Selecting a tool must deselect all other tools. The current two-way binding can leave multiple tools selected.
-- Shift+LMB should pan the view in all tools, including Cursor mode.
-- Cursor LMB drag should move any prop or robot from one cell to another.
-- Remove Rule Events UI.
-- Remove Reactor Binding UI.
-- Remove editor workflow and pending actions.
-- Door cells are redesigned as single prop cells.
-- Electricity leak neighbour should be toggled by using the electric leak tool on an existing electric leak cell.
-
-## Future Work
-- Add authored sample levels once the new schema stabilizes.
-- Tune structural integrity balancing after playtesting.
-- Extend UI affordances for inspecting per-carrier consumer service state.
+# Reactor Maintenance Tasks
 
 ## Godot Frontend Integration
 
@@ -91,7 +8,7 @@ The Godot frontend (src/ReactorMaintenance.Godot) has a complete UX scaffold (sp
 
 **Goal:** Connect LevelScreen to SimulationEngine so gameplay state flows between simulation and UI.
 
-- [ ] **Task 1.1: Create GameSession class**
+- [x] **Task 1.1: Create GameSession class**
   - Location: src/ReactorMaintenance.Godot/Data/GameSession.cs
   - Wraps SimulationEngine and holds the current LevelState
   - Loads LevelState from JSON via LevelSerializer.Deserialize() using Godot FileAccess
@@ -101,7 +18,7 @@ The Godot frontend (src/ReactorMaintenance.Godot) has a complete UX scaffold (sp
   - Validates actions before committing (rejects invalid moves)
   - Handles level start snapshot for retry
 
-- [ ] **Task 1.2: Create LevelStateLoader helper**
+- [x] **Task 1.2: Create LevelStateLoader helper**
   - Location: src/ReactorMaintenance.Godot/Data/LevelStateLoader.cs
   - Static helper that takes a res://Data/Levels/... path
   - Uses Godot FileAccess to read JSON string
@@ -109,7 +26,7 @@ The Godot frontend (src/ReactorMaintenance.Godot) has a complete UX scaffold (sp
   - Throws descriptive exceptions for missing files or schema errors
   - Supports both res:// and user:// paths
 
-- [ ] **Task 1.3: Wire LevelScreen to GameSession**
+- [x] **Task 1.3: Wire LevelScreen to GameSession**
   - Update LevelScreen.Configure() to accept GameSession instead of raw CampaignLevel
   - Replace placeholder grid with real viewport
   - Wire CellInspector.SetCellInfo() to display live selected cell data
@@ -118,7 +35,7 @@ The Godot frontend (src/ReactorMaintenance.Godot) has a complete UX scaffold (sp
   - Update LevelHeader with live global state badge (Stable/Caution/Critical/Ready)
   - Update InventoryStrip with live remedy/heat shield counts
 
-- [ ] **Task 1.4: Create res://Data/Levels/ directory and level files**
+- [x] **Task 1.4: Create res://Data/Levels/ directory and level files**
   - Create placeholder level files for the 3 campaign levels
   - Use Win2D editor to export v3 JSON schema for each level
   - Files: coolant_restart.json, fuel_bleed.json, black_start.json

src/ReactorMaintenance.Godot/Controls/CellInspector.cs

@@ -1,4 +1,6 @@
-using Godot;
+using Godot;
+using ReactorMaintenance.Simulation;
+using System.Text;
 
 namespace ReactorMaintenance.Godot.Controls;
 
@@ -18,9 +20,31 @@ public partial class CellInspector : PanelContainer
         body.AddChild(header);
 
         body.AddChild(m_Text);
-        m_Text.Text = "Selected Cell: 0,0\nTerrain: service floor\nProp: none\nHazards: none\nUnderground: hidden";
         m_Text.AutowrapMode = TextServer.AutowrapMode.WordSmart;
     }
 
+    public void SetCellInfo(GridPosition? position, ECellTerrain terrain, EPropType prop, EConsumerServiceState serviceState, float fuelHazard, float coolantHazard, float electricityHazard, float heatHazard)
+    {
+        var pos = position ?? new(-1, -1);
+        var sb = new StringBuilder();
+        sb.AppendLine($"Selected Cell: {pos.X},{pos.Y}");
+        sb.AppendLine($"Terrain: {terrain}");
+        sb.AppendLine($"Prop: {prop}");
+        if (prop != EPropType.None)
+            sb.AppendLine($"Service: {serviceState}");
+        sb.AppendLine($"Hazards: {FormatHazards(fuelHazard, coolantHazard, electricityHazard, heatHazard)}");
+        m_Text.Text = sb.ToString();
+    }
+
+    private static string FormatHazards(float fuel, float coolant, float electricity, float heat)
+    {
+        var parts = new List<string>();
+        if (fuel > 0) parts.Add($"fuel {fuel:F1}");
+        if (coolant > 0) parts.Add($"coolant {coolant:F1}");
+        if (electricity > 0) parts.Add($"electricity {electricity:F1}");
+        if (heat > 0) parts.Add($"heat {heat:F1}");
+        return parts.Count > 0 ? string.Join(", ", parts) : "none";
+    }
+
     private readonly Label m_Text = new();
-}
+}

src/ReactorMaintenance.Godot/Controls/ForecastList.cs

@@ -1,4 +1,5 @@
 using Godot;
+using ReactorMaintenance.Simulation;
 
 namespace ReactorMaintenance.Godot.Controls;
 
@@ -7,17 +8,44 @@ public partial class ForecastList : PanelContainer
     public override void _Ready()
     {
         AddChild(m_Items);
-        SetForecasts(["Turn +1: Pressure stable", "Turn +2: No forecast warnings"]);
+        SetForecasts(Array.Empty<Forecast>());
     }
 
-    public void SetForecasts(IReadOnlyList<string> forecasts)
+    public void SetForecasts(IReadOnlyList<Forecast> forecasts)
     {
         foreach (var child in m_Items.GetChildren())
             child.QueueFree();
 
         m_Items.AddChild(new Label { Text = "Forecasts" });
         foreach (var forecast in forecasts)
-            m_Items.AddChild(new Label { Text = forecast, AutowrapMode = TextServer.AutowrapMode.WordSmart });
+        {
+            var label = new Label {
+                Text = FormatForecast(forecast),
+                AutowrapMode = TextServer.AutowrapMode.WordSmart
+            };
+            ApplyForecastColor(label, forecast.Kind);
+            m_Items.AddChild(label);
+        }
+    }
+
+    private static string FormatForecast(Forecast forecast)
+    {
+        var pos = forecast.Position;
+        var posStr = pos != null ? $" [{pos.X},{pos.Y}]" : "";
+        return $"Turn +{forecast.Turns}: {forecast.Message}{posStr}";
+    }
+
+    private static void ApplyForecastColor(Label label, EForecastKind kind)
+    {
+        var color = kind switch {
+            EForecastKind.TerminalLoss => new(1.0f, 0.36f, 0.32f),
+            EForecastKind.ConsumerStarved => new(1.0f, 0.6f, 0.2f),
+            EForecastKind.HazardGrowth => new(1.0f, 0.8f, 0.2f),
+            EForecastKind.StructuralIntegrity => new(0.6f, 0.8f, 1.0f),
+            EForecastKind.ReactorReady => new(0.45f, 1.0f, 0.58f),
+            _ => Colors.White
+        };
+        label.AddThemeColorOverride("font_color", color);
     }
 
     private readonly VBoxContainer m_Items = new();

src/ReactorMaintenance.Godot/Controls/FrontendAssets.cs

@@ -4,20 +4,6 @@ namespace ReactorMaintenance.Godot.Controls;
 
 internal static class FrontendAssets
 {
-    public const string CoolantIcon = "res://Assets/Ui/coolant_icon.png";
-    public const string ElectricIcon = "res://Assets/Ui/electric_icon.png";
-    public const string FuelIcon = "res://Assets/Ui/fuel_icon.png";
-    public const string HeatShieldIcon = "res://Assets/Ui/heat_shield_icon.png";
-    public const string MaintenanceRobot = "res://Assets/Characters/maintenance_robot.png";
-    public const string PrimaryButtonAccent = "res://Assets/Ui/primary_button_accent.png";
-    public const string ScannerEyeIcon = "res://Assets/Ui/scanner_eye_icon.png";
-    public const string StateBadgeFrame = "res://Assets/Ui/state_badge_frame.png";
-
-    public static Texture2D? LoadTexture(string path)
-    {
-        return ResourceLoader.Exists(path) ? ResourceLoader.Load<Texture2D>(path) : null;
-    }
-
     public static TextureRect CreateIcon(string path, Vector2 size)
     {
         return new() {
@@ -28,4 +14,18 @@ internal static class FrontendAssets
             MouseFilter = Control.MouseFilterEnum.Ignore
         };
     }
-}
+
+    public static Texture2D? LoadTexture(string path)
+    {
+        return ResourceLoader.Exists(path) ? ResourceLoader.Load<Texture2D>(path) : null;
+    }
+
+    public const string CoolantIcon = "res://Assets/Ui/coolant_icon.png";
+    public const string ElectricIcon = "res://Assets/Ui/electric_icon.png";
+    public const string FuelIcon = "res://Assets/Ui/fuel_icon.png";
+    public const string HeatShieldIcon = "res://Assets/Ui/heat_shield_icon.png";
+    public const string MaintenanceRobot = "res://Assets/Characters/maintenance_robot.png";
+    public const string PrimaryButtonAccent = "res://Assets/Ui/primary_button_accent.png";
+    public const string ScannerEyeIcon = "res://Assets/Ui/scanner_eye_icon.png";
+    public const string StateBadgeFrame = "res://Assets/Ui/state_badge_frame.png";
+}

src/ReactorMaintenance.Godot/Controls/InventoryStrip.cs

@@ -1,4 +1,4 @@
-using Godot;
+using Godot;
 
 namespace ReactorMaintenance.Godot.Controls;
 
@@ -6,23 +6,43 @@ public partial class InventoryStrip : HBoxContainer
 {
     public override void _Ready()
     {
-        AddChild(CreateItem("Fuel Neutralizer", 2, FrontendAssets.FuelIcon));
-        AddChild(CreateItem("Coolant Neutralizer", 2, FrontendAssets.CoolantIcon));
-        AddChild(CreateItem("Electric Neutralizer", 1, FrontendAssets.ElectricIcon));
-        AddChild(CreateItem("Heat Shield", 1, FrontendAssets.HeatShieldIcon));
+        AddChild(CreateItem("Fuel Neutralizer", 2, FrontendAssets.FuelIcon, out var fuelLabel));
+        AddChild(CreateItem("Coolant Neutralizer", 2, FrontendAssets.CoolantIcon, out var coolantLabel));
+        AddChild(CreateItem("Electric Neutralizer", 1, FrontendAssets.ElectricIcon, out var electricLabel));
+        AddChild(CreateItem("Heat Shield", 1, FrontendAssets.HeatShieldIcon, out var heatLabel));
+        m_FuelLabel = fuelLabel;
+        m_CoolantLabel = coolantLabel;
+        m_ElectricLabel = electricLabel;
+        m_HeatLabel = heatLabel;
     }
 
-    private static HBoxContainer CreateItem(string name, int count, string iconPath)
+    public void SetInventory(int fuelNeutralizers, int coolantNeutralizers, int electricNeutralizers, int heatShields)
+    {
+        m_FuelLabel.Text = $"{fuelNeutralizers}";
+        m_CoolantLabel.Text = $"{coolantNeutralizers}";
+        m_ElectricLabel.Text = $"{electricNeutralizers}";
+        m_HeatLabel.Text = $"{heatShields}";
+    }
+
+    private static HBoxContainer CreateItem(string name, int count, string iconPath, out Label countLabel)
     {
         var item = new HBoxContainer {
             SizeFlagsHorizontal = SizeFlags.ExpandFill
         };
         item.AddChild(FrontendAssets.CreateIcon(iconPath, new(30, 30)));
-        item.AddChild(new Label {
-            Text = $"{name}: {count}",
+        countLabel = new() {
+            Text = $"{count}",
+            Name = name,
             HorizontalAlignment = HorizontalAlignment.Center,
             SizeFlagsHorizontal = SizeFlags.ExpandFill
-        });
+        };
+        item.AddChild(countLabel);
         return item;
     }
-}
+
+    private Label m_CoolantLabel = null!;
+    private Label m_ElectricLabel = null!;
+
+    private Label m_FuelLabel = null!;
+    private Label m_HeatLabel = null!;
+}

src/ReactorMaintenance.Godot/Controls/LevelHeader.cs

@@ -1,5 +1,5 @@
 using Godot;
-using ReactorMaintenance.Godot.Data;
+using ReactorMaintenance.Simulation;
 
 namespace ReactorMaintenance.Godot.Controls;
 
@@ -18,12 +18,25 @@ public partial class LevelHeader : HBoxContainer
         m_Summary.HorizontalAlignment = HorizontalAlignment.Right;
     }
 
-    public void SetLevel(CampaignLevel level, int levelNumber, int levelCount, string state)
+    public void SetLevel(string title, int levelNumber, int levelCount, ELevelState state)
     {
-        m_Title.Text = level.Name;
+        m_Title.Text = title;
         m_Progress.Text = $"Level {levelNumber} / {levelCount}";
-        m_Badge.SetState(state);
-        m_Summary.Text = "Heat nominal | Reactor offline";
+        m_Badge.SetState(StateToString(state));
+        m_Summary.Text = "Heat: nominal | Reactor: offline";
+    }
+
+    private static string StateToString(ELevelState state)
+    {
+        return state switch {
+            ELevelState.Stable => "Stable",
+            ELevelState.Caution => "Caution",
+            ELevelState.Critical => "Critical",
+            ELevelState.Ready => "Ready",
+            ELevelState.Lost => "Lost",
+            ELevelState.Won => "Won",
+            _ => "Unknown"
+        };
     }
 
     private readonly StateBadge m_Badge = new();

src/ReactorMaintenance.Godot/Controls/PrimaryButton.cs

@@ -21,4 +21,4 @@ public partial class PrimaryButton : Button
         TooltipText = tooltip;
         Disabled = disabled;
     }
-}
+}

src/ReactorMaintenance.Godot/Controls/StateBadge.cs

@@ -48,4 +48,4 @@ public partial class StateBadge : PanelContainer
     }
 
     private readonly Label m_Text = new();
-}
+}

src/ReactorMaintenance.Godot/Data/GameSession.cs

@@ -0,0 +1,121 @@
+using ReactorMaintenance.Simulation;
+
+namespace ReactorMaintenance.Godot.Data;
+
+public sealed class GameSession
+{
+    public event StateChangedHandler? LevelStateChanged;
+    public event StateChangedHandler? RobotMoved;
+    public event StateChangedHandler? TurnAdvanced;
+    public event StateChangedHandler? LevelWon;
+    public event StateChangedHandler? LevelLost;
+
+    public void Initialize(LevelState levelState)
+    {
+        LevelState = levelState;
+        m_StartSnapshot = LevelSerializer.Deserialize(LevelSerializer.Serialize(levelState));
+    }
+
+    public bool MoveRobot(GridPosition destination)
+    {
+        if (LevelState.Terrain[(destination.Y * LevelState.Width) + destination.X] == ECellTerrain.Wall)
+            return false;
+
+        if (destination.X < 0 || destination.X >= LevelState.Width ||
+            destination.Y < 0 || destination.Y >= LevelState.Height)
+            return false;
+
+        LevelState = m_Engine.MoveRobot(LevelState, destination);
+        RobotMoved?.Invoke(this);
+        return true;
+    }
+
+    public LevelState EndTurn()
+    {
+        LevelState = m_Engine.EndTurn(LevelState);
+        OnTurnAdvanced();
+        return LevelState;
+    }
+
+    public bool InteractProp()
+    {
+        if (LevelState.Global.LevelState is ELevelState.Lost or ELevelState.Won)
+            return false;
+
+        LevelState = m_Engine.InteractProp(LevelState);
+        OnTurnAdvanced();
+        return true;
+    }
+
+    public bool InteractLeak(ECarrierType carrier, bool useRemedy)
+    {
+        if (LevelState.Global.LevelState is ELevelState.Lost or ELevelState.Won)
+            return false;
+
+        LevelState = m_Engine.InteractLeak(LevelState, carrier, useRemedy);
+        OnTurnAdvanced();
+        return true;
+    }
+
+    public bool ApplyHeatShield()
+    {
+        if (LevelState.Global.LevelState is ELevelState.Lost or ELevelState.Won)
+            return false;
+
+        LevelState = m_Engine.ApplyHeatShield(LevelState);
+        OnTurnAdvanced();
+        return true;
+    }
+
+    public bool ActivateReactor()
+    {
+        if (LevelState.Global.LevelState is ELevelState.Lost or ELevelState.Won)
+            return false;
+
+        LevelState = m_Engine.ActivateReactor(LevelState);
+        CheckOutcome();
+        return true;
+    }
+
+    public IReadOnlyList<Forecast> GetForecasts()
+    {
+        return m_Engine.Forecast(LevelState);
+    }
+
+    public void Retry()
+    {
+        LevelState = m_StartSnapshot;
+        LevelStateChanged?.Invoke(this);
+    }
+
+    private void OnTurnAdvanced()
+    {
+        CheckOutcome();
+        TurnAdvanced?.Invoke(this);
+    }
+
+    private void CheckOutcome()
+    {
+        if (LevelState.Global.LevelState == ELevelState.Won)
+            LevelWon?.Invoke(this);
+        else if (LevelState.Global.LevelState == ELevelState.Lost)
+            LevelLost?.Invoke(this);
+    }
+
+    public LevelState LevelState { get; private set; } = null!;
+    public GridPosition RobotPosition => LevelState.Robot.Position;
+    public GlobalState GlobalState => LevelState.Global;
+    public IReadOnlyList<Forecast> Forecasts => LevelState.Forecasts;
+    public IReadOnlyList<LeakState> Leaks => LevelState.Leaks;
+    public IReadOnlyList<ReactorState> Reactors => LevelState.Reactors;
+    public IReadOnlyList<PropState> Props => LevelState.Props;
+    public ECellTerrain[] Terrain => LevelState.Terrain;
+    public SurfaceState[] Surface => LevelState.Surface;
+    public UndergroundCell[] UndergroundFuel => LevelState.Fuel;
+    public UndergroundCell[] UndergroundCoolant => LevelState.Coolant;
+    public UndergroundCell[] UndergroundElectricity => LevelState.Electricity;
+    public delegate void StateChangedHandler(GameSession sender);
+
+    private readonly SimulationEngine m_Engine = new();
+    private LevelState m_StartSnapshot = null!;
+}

src/ReactorMaintenance.Godot/Data/LevelStateLoader.cs

@@ -0,0 +1,34 @@
+using ReactorMaintenance.Simulation;
+using FileAccess = Godot.FileAccess;
+
+namespace ReactorMaintenance.Godot.Data;
+
+public static class LevelStateLoader
+{
+    public static LevelState Load(string path)
+    {
+        if (string.IsNullOrWhiteSpace(path))
+            throw new ArgumentException("Level path must not be null or empty.", nameof(path));
+
+        if (!FileAccess.FileExists(path))
+            throw new FileNotFoundException($"Level file not found: {path}");
+
+        var json = FileAccess.GetFileAsString(path);
+        if (string.IsNullOrWhiteSpace(json))
+            throw new InvalidOperationException($"Level file is empty: {path}");
+
+        try
+        {
+            return LevelSerializer.Deserialize(json);
+        }
+        catch (InvalidOperationException)
+        {
+            throw;
+        }
+        catch (Exception ex)
+        {
+            throw new InvalidOperationException(
+                $"Failed to deserialize level from {path}: {ex.Message}", ex);
+        }
+    }
+}

src/ReactorMaintenance.Godot/Screens/LevelScreen.cs

@@ -1,20 +1,23 @@
-using Godot;
+using Godot;
 using ReactorMaintenance.Godot.Controls;
 using ReactorMaintenance.Godot.Data;
+using ReactorMaintenance.Simulation;
 
 namespace ReactorMaintenance.Godot.Screens;
 
 public partial class LevelScreen : ScreenBase
 {
-    public void Configure(AppController app, CampaignLevel level, int levelNumber, int levelCount)
+    public void Configure(AppController app, GameSession session, CampaignLevel level, int levelNumber, int levelCount)
     {
         m_App = app;
+        m_Session = session;
         m_Level = level;
+        m_OutcomeVisible = false;
 
         var body = CreatePage(string.Empty);
         var header = new LevelHeader();
         body.AddChild(header);
-        header.SetLevel(level, levelNumber, levelCount, "Stable");
+        header.SetLevel(level.Name, levelNumber, levelCount, session.LevelState.Global.LevelState);
 
         var flavor = CreateBodyText(level.FlavorText);
         flavor.HorizontalAlignment = HorizontalAlignment.Left;
@@ -23,109 +26,163 @@ public partial class LevelScreen : ScreenBase
         var split = new HSplitContainer { SizeFlagsVertical = SizeFlags.ExpandFill };
         body.AddChild(split);
 
-        split.AddChild(CreateGridPlaceholder());
-        split.AddChild(CreateSidePanel(level));
+        m_GridPanel = CreateGridContainer();
+        split.AddChild(m_GridPanel);
 
-        body.AddChild(new InventoryStrip());
+        m_Inspector = new();
+        m_ForecastList = new();
+        var sidePanel = new VBoxContainer { CustomMinimumSize = new(300, 0) };
+        sidePanel.AddChild(m_Inspector);
+        sidePanel.AddChild(m_ForecastList);
+        split.AddChild(sidePanel);
+
+        m_InventoryStrip = new();
+        body.AddChild(m_InventoryStrip);
         body.AddChild(CreateActionBar());
 
         m_OverlayLayer = new();
         AddChild(m_OverlayLayer);
+
+        UpdateUI();
+        m_Session.LevelStateChanged += OnLevelStateChanged;
+        m_Session.TurnAdvanced += OnTurnAdvanced;
     }
 
-    private static PanelContainer CreateGridPlaceholder()
+    private PanelContainer CreateGridContainer()
     {
-        var panel = new PanelContainer { CustomMinimumSize = new(560, 360), SizeFlagsHorizontal = SizeFlags.ExpandFill, SizeFlagsVertical = SizeFlags.ExpandFill };
-        var viewport = new Control {
+        return new() {
+            CustomMinimumSize = new(560, 360),
             SizeFlagsHorizontal = SizeFlags.ExpandFill,
             SizeFlagsVertical = SizeFlags.ExpandFill
         };
-        panel.AddChild(viewport);
-
-        var label = new Label {
-            Text = "Level Grid Placeholder\nRobot marker, terrain, props, hazards, and underground overlays will render here.",
-            AnchorRight = 1,
-            AnchorBottom = 1,
-            HorizontalAlignment = HorizontalAlignment.Center,
-            VerticalAlignment = VerticalAlignment.Center,
-            AutowrapMode = TextServer.AutowrapMode.WordSmart
-        };
-        viewport.AddChild(label);
-
-        var robot = new TextureRect {
-            Texture = FrontendAssets.LoadTexture(FrontendAssets.MaintenanceRobot),
-            AnchorLeft = 0.5f,
-            AnchorTop = 0.5f,
-            AnchorRight = 0.5f,
-            AnchorBottom = 0.5f,
-            OffsetLeft = -48,
-            OffsetTop = -32,
-            OffsetRight = 48,
-            OffsetBottom = 64,
-            ExpandMode = TextureRect.ExpandModeEnum.FitWidthProportional,
-            StretchMode = TextureRect.StretchModeEnum.KeepAspectCentered,
-            MouseFilter = Control.MouseFilterEnum.Ignore
-        };
-        viewport.AddChild(robot);
-
-        return panel;
-    }
-
-    private static VBoxContainer CreateSidePanel(CampaignLevel level)
-    {
-        var sidePanel = new VBoxContainer { CustomMinimumSize = new(300, 0) };
-        sidePanel.AddChild(new CellInspector());
-        sidePanel.AddChild(new ForecastList());
-        sidePanel.AddChild(new Label { Text = $"Level JSON: {level.LevelPath}", AutowrapMode = TextServer.AutowrapMode.WordSmart });
-        return sidePanel;
     }
 
     private HBoxContainer CreateActionBar()
     {
         var actions = new HBoxContainer();
-        actions.AddChild(CreateButton("Move", () => { }, "Quick action placeholder"));
-        actions.AddChild(CreateButton("Interact", () => { }, "Lengthy action placeholder"));
-        actions.AddChild(CreateButton("Repair", () => { }, "Lengthy action placeholder"));
-        actions.AddChild(CreateButton("Trigger Win", ShowWinOverlay));
-        actions.AddChild(CreateButton("Trigger Lose", ShowLoseOverlay));
+        actions.AddChild(CreateButton("Move", OnMoveAction, "Move robot to adjacent floor cell"));
+        actions.AddChild(CreateButton("Interact", OnInteractAction, "Interact with prop at robot position"));
+        actions.AddChild(CreateButton("Repair", OnRepairAction, "Repair leak at robot position"));
+        actions.AddChild(CreateButton("End Turn", OnEndTurnAction));
         actions.AddChild(CreateButton("Main Menu", () => m_App?.ShowMainMenu()));
         return actions;
     }
 
-    private void ShowLoseOverlay()
+    private void OnMoveAction()
+    {
+        if (m_Session is null) return;
+
+        var current = m_Session.RobotPosition;
+        var next = current with { X = current.X + 1 };
+        if (!m_Session.MoveRobot(next))
+        {
+            next = current with { Y = current.Y + 1 };
+            m_Session.MoveRobot(next);
+        }
+    }
+
+    private void OnInteractAction()
+    {
+        m_Session?.InteractProp();
+    }
+
+    private void OnRepairAction()
+    {
+        if (m_Session is null) return;
+
+        foreach (var leak in m_Session.Leaks)
+        {
+            if (leak.AccessPosition == m_Session.RobotPosition && !leak.Repaired)
+            {
+                m_Session.InteractLeak(leak.Carrier, true);
+                return;
+            }
+        }
+    }
+
+    private void OnEndTurnAction()
+    {
+        m_Session?.EndTurn();
+    }
+
+    private void UpdateUI()
+    {
+        if (m_Session is null || m_Inspector is null || m_ForecastList is null || m_InventoryStrip is null)
+            return;
+
+        var ls = m_Session.LevelState;
+        var robotPos = m_Session.RobotPosition;
+        var index = (robotPos.Y * ls.Width) + robotPos.X;
+        var surface = ls.Surface[index];
+        var prop = index < ls.Props.Length ? ls.Props[index] : new();
+
+        m_Inspector.SetCellInfo(
+            robotPos,
+            ls.Terrain[index],
+            prop.Type,
+            prop.ServiceState,
+            surface.Fuel,
+            surface.Coolant,
+            surface.Electricity,
+            surface.Heat);
+
+        m_ForecastList.SetForecasts(ls.Forecasts);
+
+        m_InventoryStrip.SetInventory(
+            m_Session.LevelState.Robot.FuelNeutralizers,
+            m_Session.LevelState.Robot.CoolantNeutralizers,
+            m_Session.LevelState.Robot.ElectricityNeutralizers,
+            m_Session.LevelState.Robot.HeatShields);
+    }
+
+    private void OnLevelStateChanged(GameSession sender)
+    {
+        UpdateUI();
+    }
+
+    private void OnTurnAdvanced(GameSession sender)
+    {
+        UpdateUI();
+        if (sender.LevelState.Global.LevelState is ELevelState.Lost or ELevelState.Won)
+        {
+            ShowOutcomeOverlay(sender.LevelState.Global.LevelState);
+        }
+    }
+
+    private void ShowOutcomeOverlay(ELevelState state)
     {
         if (m_OutcomeVisible || m_App is null || m_Level is null || m_OverlayLayer is null)
             return;
 
         m_OutcomeVisible = true;
-        var overlay = new LoseOverlay();
-        overlay.Configure(m_Level, m_App.RetryCurrentLevel, m_App.ShowGameOver, m_App.ShowMainMenu);
-        AddCenteredOverlay(overlay);
-    }
+        Control overlay;
 
-    private void ShowWinOverlay()
-    {
-        if (m_OutcomeVisible || m_App is null || m_Level is null || m_OverlayLayer is null)
-            return;
+        if (state == ELevelState.Won)
+        {
+            overlay = new WinOverlay();
+            ((WinOverlay)overlay).Configure(m_Level, m_App.CompleteCurrentLevel, m_App.ShowMainMenu);
+        }
+        else
+        {
+            overlay = new LoseOverlay();
+            ((LoseOverlay)overlay).Configure(m_Level, m_App.RetryCurrentLevel, m_App.ShowGameOver, m_App.ShowMainMenu);
+        }
 
-        m_OutcomeVisible = true;
-        var overlay = new WinOverlay();
-        overlay.Configure(m_Level, m_App.CompleteCurrentLevel, m_App.ShowMainMenu);
-        AddCenteredOverlay(overlay);
-    }
-
-    private void AddCenteredOverlay(Control overlay)
-    {
         var center = new CenterContainer {
             AnchorRight = 1,
             AnchorBottom = 1
         };
         center.AddChild(overlay);
-        m_OverlayLayer?.AddChild(center);
+        m_OverlayLayer.AddChild(center);
     }
 
     private AppController? m_App;
+    private ForecastList? m_ForecastList;
+    private PanelContainer? m_GridPanel;
+    private CellInspector? m_Inspector;
+    private InventoryStrip? m_InventoryStrip;
     private CampaignLevel? m_Level;
     private bool m_OutcomeVisible;
     private CanvasLayer? m_OverlayLayer;
-}
+    private GameSession? m_Session;
+}

src/ReactorMaintenance.Godot/Scripts/AppController.cs

@@ -47,7 +47,11 @@ public partial class AppController : Control
     public void LoadCurrentLevel()
     {
         m_Session.MarkCurrentLevelLoaded();
-        ShowScreen<LevelScreen>("res://Scenes/LevelScreen.tscn", screen => screen.Configure(this, m_Session.CurrentLevel, m_Session.LevelNumber, m_Session.LevelCount));
+        var level = m_Session.CurrentLevel;
+        var gameSession = new GameSession();
+        var levelState = LevelStateLoader.Load(level.LevelPath);
+        gameSession.Initialize(levelState);
+        ShowScreen<LevelScreen>("res://Scenes/LevelScreen.tscn", screen => screen.Configure(this, gameSession, level, m_Session.LevelNumber, m_Session.LevelCount));
     }
 
     public void RetryCurrentLevel()