Extract VM runtime settings handler

docs/PROJECT-STRUCTURE.md

@@ -216,6 +216,8 @@ string comparison/concatenation/conversion/move, native byte-length and CP932 op
 fullwidth string editor; shared operand storage, addressing, and native-string encoding remain in the coordinator.
 `engine/Age.Engine/Vm/VirtualMachine.Diagnostics.cs` owns diagnostic value/newline accumulation and synchronous
 show-and-clear opcode dispatch; shared diagnostic state and native-context formatting remain in the coordinator.
+`engine/Age.Engine/Vm/VirtualMachine.RuntimeSettings.cs` owns message-window alpha and system-menu enable/show
+delay opcode dispatch; reset/default initialization, public menu-state accessors, and host state remain centralized.
 
 The disposable `build/page-map-<SCENE>.jsonl` files are produced by editor/development Godot runs and map
 runtime ADV page ordinals to their authoritative script offsets for `tools/locate_page.py`. Packaged exports

docs/remake-architecture-and-roadmap.md

@@ -734,6 +734,13 @@ do not mix mechanical moves with semantic changes.
    instruction through guarded `StepDiagnostic`; shared accumulator state and native-context formatting remain
    in the coordinator. Runtime validation remains green.
 
+   The eighteenth bounded `VirtualMachine.Step` extraction moved message-window alpha get/set, system-menu
+   enable state, and system-menu show-delay get/set into
+   `engine/Age.Engine/Vm/VirtualMachine.RuntimeSettings.cs`. The top-level dispatcher retains all labels and
+   aliases at their existing positions and routes them through guarded `StepRuntimeSetting`; reset/default
+   initialization, public menu-state accessors, and host state remain centralized. Runtime validation remains
+   green.
+
    **Gate:** no externally visible behavior or command changes; generated artifacts are byte-identical where
    deterministic, and the corresponding engine, Python, Godot, and corpus validations remain green after
    each domain move.
@@ -1107,8 +1114,9 @@ Continue step 2 of the **codebase consolidation** maintenance slice: behavior-ne
 by the tracked launcher and layered validation driver. With the planned `Main`, `GodotAdvHost`, and `GfxState`
 domains isolated and the audio, movie, surface/texture, retained-object, animation, presentation, ADV-text,
 text-history, ADV-service, input, timing, persistence, and memory/collection `VirtualMachine.Step` families routed
-through domain handlers, with control-flow/coroutine, process/root-exit/cross-script lifecycle, value, and
-diagnostic dispatch now isolated as well, extract message-window and system-menu runtime settings
-next without replacing the proven dispatcher or changing public types, commands, and generated output.
+through domain handlers, with control-flow/coroutine, process/root-exit/cross-script lifecycle, value,
+diagnostic, and runtime-setting dispatch now isolated as well, route the four remaining recognized opcode bodies
+for script entry/root state and surface reload policy into their existing domain handlers, leaving `Step` as the
+proven dispatcher and unknown-op fallback without changing public types, commands, and generated output.
 Concrete playthrough blockers may still preempt this bounded maintenance work; the consolidation effort does
 not replace Phase B gameplay validation or the open cross-platform gates.

engine/Age.Engine/Vm/VirtualMachine.RuntimeSettings.cs

@@ -0,0 +1,36 @@
+using Age.Engine.Model;
+
+namespace Age.Engine.Vm;
+
+public sealed partial class VirtualMachine
+{
+    private int StepRuntimeSetting(string label, IReadOnlyList<Operand> a, int pc)
+    {
+        switch (label)
+        {
+            case "get-message-window-alpha": // 0x131: process-owned message:MesWinAlpha setting
+            case "u00415F70":
+                Write(a[0], _messageWindowAlphaSetting);
+                return pc + 1;
+            case "set-message-window-alpha": // 0x141: paired message:MesWinAlpha configuration setter
+            case "u0041FAA0":
+                _messageWindowAlphaSetting = (int)Read(a[0]);
+                _host.SetMessageWindowAlphaSetting(_messageWindowAlphaSetting);
+                return pc + 1;
+            case "set-system-menu-enabled": // 0x142: native AGERC menu reentrancy guard
+            case "u0041FB10": // pre-reference compatibility
+                _systemMenuActionsEnabled = unchecked((int)Read(a[0]));
+                return pc + 1;
+            case "get-system-menu-show-delay": // 0x148: paired TIMER_SHOWMENU getter
+            case "u004160A0": // pre-reference compatibility
+                Write(a[0], unchecked((int)_systemMenuShowDelayMilliseconds));
+                return pc + 1;
+            case "set-system-menu-show-delay": // 0x149: top-edge dwell threshold in milliseconds
+            case "u0041FCE0": // pre-reference compatibility
+                _systemMenuShowDelayMilliseconds = unchecked((uint)Read(a[0]));
+                return pc + 1;
+            default:
+                throw new InvalidOperationException($"Non-runtime-setting opcode routed to runtime-setting handler: {label}");
+        }
+    }
+}

engine/Age.Engine/Vm/VirtualMachine.cs

@@ -1444,24 +1444,15 @@ public sealed partial class VirtualMachine
                 return StepAdvText(label, ins, pc);
             case "get-message-window-alpha": // 0x131: process-owned message:MesWinAlpha setting
             case "u00415F70":
-                Write(a[0], _messageWindowAlphaSetting); return pc + 1;
             case "set-message-window-alpha": // 0x141: paired message:MesWinAlpha configuration setter
             case "u0041FAA0":
-                _messageWindowAlphaSetting = (int)Read(a[0]);
-                _host.SetMessageWindowAlphaSetting(_messageWindowAlphaSetting);
-                return pc + 1;
             case "set-system-menu-enabled": // 0x142: native AGERC menu reentrancy guard
             case "u0041FB10": // pre-reference compatibility
-                _systemMenuActionsEnabled = unchecked((int)Read(a[0]));
-                return pc + 1;
             case "get-system-menu-show-delay": // 0x148: paired TIMER_SHOWMENU getter
             case "u004160A0": // pre-reference compatibility
-                Write(a[0], unchecked((int)_systemMenuShowDelayMilliseconds));
-                return pc + 1;
             case "set-system-menu-show-delay": // 0x149: top-edge dwell threshold in milliseconds
             case "u0041FCE0": // pre-reference compatibility
-                _systemMenuShowDelayMilliseconds = unchecked((uint)Read(a[0]));
-                return pc + 1;
+                return StepRuntimeSetting(label, a, pc);
             case "get-message-glyph-delay": // 0x7f
             case "u00414C60":
             case "set-message-glyph-delay": // 0x1b5