feat(gfx): execute gfx command-buffer query/set/lifecycle ops in the VM

Gfx property on VirtualMachine + dispatch cases for the query ops (0x215/0x216/
0x218/0x21a), set ops (0x217/0x219/0x1ff/0x212/0x213) and lifecycle (0x1a2/0x1f7/
0x1fa). Query ops write results to operands like get-texture-size; set ops mutate
GfxState. Round-trip + distinct-slot tests pass; full suite 36 green (parity held).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

engine/Age.Engine.Tests/GfxCommandBufferTests.cs

@@ -0,0 +1,55 @@
+using System.Collections.Generic;
+using Age.Engine.Model;
+using Age.Engine.Sys4;
+using Age.Engine.Vm;
+using Xunit;
+
+public class GfxCommandBufferTests
+{
+    private static OpcodeTable T() => OpcodeTableJson.Load(Paths.OpcodesJson);
+    private static Operand G(int addr) => new(3, addr);   // global-int
+    private static Operand I(long v) => new(0, v);        // immediate
+
+    // op ctor helpers (0x217 set-geom3, 0x218 get-geom3, 0x215 query, 0x55 mov, 0x2 exit)
+    private static (int, Operand[]) SetGeom3(int handle, int a, int b, int c) => (0x217, new[] { G(handle), G(a), G(b), G(c) });
+    private static (int, Operand[]) GetGeom3(int handle, int a, int b, int c) => (0x218, new[] { G(handle), G(a), G(b), G(c) });
+    private static (int, Operand[]) Query(int outAddr, int handle) => (0x215, new[] { G(outAddr), G(handle) });
+    private static (int, Operand[]) MovGI(int dst, long v) => (0x55, new[] { G(dst), I(v) });
+    private static (int, Operand[]) Exit() => (0x2, System.Array.Empty<Operand>());
+
+    [Fact]
+    public void SetThenGetGeom3RoundTripsThroughTheObject()
+    {
+        var t = T();
+        // g[1]=handle; set V18 from g[2,3,4]=(10,20,30); read V18 back into g[5,6,7]; then exit.
+        var scene = ScriptAssembler.Assemble(t, "GFX", new List<(int, Operand[])>
+        {
+            MovGI(1, 0x1000), MovGI(2, 10), MovGI(3, 20), MovGI(4, 30),
+            SetGeom3(1, 2, 3, 4),
+            GetGeom3(1, 5, 6, 7),
+            Exit(),
+        }, System.Array.Empty<string>());
+        var vm = new VirtualMachine(scene, t, new RecordingHost());
+        vm.Run();
+        Assert.Equal(10, vm.Globals[5]);
+        Assert.Equal(20, vm.Globals[6]);
+        Assert.Equal(30, vm.Globals[7]);
+    }
+
+    [Fact]
+    public void QueryReturnsDistinctSlotsPerHandle_NotZero()
+    {
+        var t = T();
+        // create two objects via set-geom, then query each into g[10], g[11].
+        var scene = ScriptAssembler.Assemble(t, "GFX", new List<(int, Operand[])>
+        {
+            MovGI(1, 0x1000), MovGI(2, 0x2000), MovGI(3, 0),
+            SetGeom3(1, 3, 3, 3), SetGeom3(2, 3, 3, 3),
+            Query(10, 1), Query(11, 2), Exit(),
+        }, System.Array.Empty<string>());
+        var vm = new VirtualMachine(scene, t, new RecordingHost());
+        vm.Run();
+        Assert.NotEqual(0, vm.Globals[10]);              // not collapsed to slot 0
+        Assert.NotEqual(vm.Globals[10], vm.Globals[11]); // distinct slots => no collapse
+    }
+}

engine/Age.Engine/Vm/VirtualMachine.cs

@@ -23,6 +23,7 @@ public sealed class VirtualMachine
 
     public Dictionary<int, long> Globals { get; } = new();
     public Dictionary<int, string> GlobalStrings { get; } = new();
+    public GfxState Gfx { get; } = new();
     public List<(int Offset, string Text, string Script)> Emitted { get; } = new();
     public string? HaltReason { get; private set; }
     public long Steps { get; private set; }
@@ -225,6 +226,38 @@ public sealed class VirtualMachine
             }
             case "play-bgm":   _host.PlayBgm(Read(a[0])); return pc + 1;
             case "play-voice": _host.PlayVoice(Read(a[0])); return pc + 1;
+            // ---- gfx command-buffer ops (VM-internal GfxState; docs/engine-re.md op-contract table) ----
+            case "query-gfx-object?":   // 0x215 (out)(handle) -> slot | -1
+                Write(a[0], Gfx.QuerySlot(Read(a[1]))); return pc + 1;
+            case "query-gfx-field?":    // 0x216 (out)(idx)
+                Write(a[0], Gfx.QueryField(Read(a[1]))); return pc + 1;
+            case "get-gfx-geom3?":      // 0x218 (handle)(outA)(outB)(outC) <- V18
+            {
+                var v = Gfx.TryGet(Read(a[0]))?.V18 ?? default;
+                Write(a[1], v.X); Write(a[2], v.Y); Write(a[3], v.Z); return pc + 1;
+            }
+            case "get-gfx-geom3-b?":    // 0x21a (handle)(outA)(outB)(outC) <- V24
+            {
+                var v = Gfx.TryGet(Read(a[0]))?.V24 ?? default;
+                Write(a[1], v.X); Write(a[2], v.Y); Write(a[3], v.Z); return pc + 1;
+            }
+            case "set-gfx-geom3":       // 0x217 (handle)(a)(b)(c) -> V18
+                Gfx.GetOrCreate(Read(a[0])).V18 = (Read(a[1]), Read(a[2]), Read(a[3])); return pc + 1;
+            case "set-gfx-geom3-b":     // 0x219 (handle)(a)(b)(c) -> V24
+                Gfx.GetOrCreate(Read(a[0])).V24 = (Read(a[1]), Read(a[2]), Read(a[3])); return pc + 1;
+            case "set-gfx-geom3-c":     // 0x1ff (handle)(a)(b)(c) -> V16c
+                Gfx.GetOrCreate(Read(a[0])).V16c = (Read(a[1]), Read(a[2]), Read(a[3])); return pc + 1;
+            case "set-gfx-field64":     // 0x212 (idx)(val)
+                Gfx.GetOrCreate(Read(a[0])).Field64 = Read(a[1]); return pc + 1;
+            case "set-gfx-xy":          // 0x213 (idx)(x)(y)
+            {
+                var o = Gfx.GetOrCreate(Read(a[0])); o.Field68 = Read(a[1]); o.Field6c = Read(a[2]); return pc + 1;
+            }
+            case "gfx-cmd-register":    // 0x1a2 (val) — register/select
+            case "gfx-elem-create":     // 0x1f7 (handle)(count) — ensure object + slot
+                Gfx.GetOrCreate(Read(a[0])); return pc + 1;
+            case "gfx-elem-release":    // 0x1fa (handle)
+                Gfx.Release(Read(a[0])); return pc + 1;
             default:
                 // Stub is per-instruction frequency (the VM handles ~30 ops; the rest hit here, e.g.
                 // 0x258/0x259 stmt markers appear en masse), so gate it with Step — else --trace floods.