Add subroutine-execution diagnostics + Godot --scene

- CLI run: report call-script dispatch count + distinct source scripts per run.
- Godot --scene <NAME>: play any scene (not just SC0000).
- Godot reports the call-scripts executed as nested frames at scene end (collected
  thread-safely; Godot drops GD.Print from the VM background thread).

Demonstrated live: SC0240 in Godot executes 29 call-scripts (RESETLAND, SETEN,
ADDEN, RENDERMAP, SETOBJ, DRAWOBJ, CALCREVISE, LOOK) as nested subroutine frames.

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

engine/Age.Cli/Program.cs

@@ -14,10 +14,13 @@ if (args.Length == 0) { Console.WriteLine("usage: run <file> | trace <out.json>"
 if (args[0] == "run")
 {
     var script = Sys4Loader.Load(args[1], table);
-    var vm = new VirtualMachine(script, table, new CaptureHost(), null, provider);
+    var runHost = new CaptureHost();
+    var vm = new VirtualMachine(script, table, runHost, null, provider);
     vm.Run();
-    Console.WriteLine($"{Path.GetFileName(args[1])}: {vm.Steps} steps, {vm.Emitted.Count} show-text (halt: {vm.HaltReason})");
+    Console.WriteLine($"{Path.GetFileName(args[1])}: {vm.Steps} steps, {vm.Emitted.Count} show-text, {runHost.CallScriptCount} call-scripts (halt: {vm.HaltReason})");
-    foreach (var (off, text, _) in vm.Emitted.Take(20)) Console.WriteLine($"  [{off:x}] {text}");
+    foreach (var (off, text, scr) in vm.Emitted.Take(30)) Console.WriteLine($"  [{scr} 0x{off:x}] {text}");
+    var sources = vm.Emitted.Select(e => e.Script).Distinct().ToList();
+    Console.WriteLine($"source scripts ({sources.Count}): {string.Join(", ", sources)}");
     return 0;
 }
 

godot/GodotAdvHost.cs

@@ -42,7 +42,10 @@ public sealed class GodotAdvHost : IHost
     // called from the main thread (click) or the selftest auto-clicker
     public void SignalInput() { if (_gate.CurrentCount == 0) _gate.Release(); }
 
-    public void CallScript(long id) { }
+    // Records each call-script the VM dispatches (runs on the VM thread, so collect thread-safely and
+    // let the main thread report it — Godot drops GD.Print from background threads).
+    public readonly System.Collections.Concurrent.ConcurrentQueue<long> Dispatched = new();
+    public void CallScript(long id) => Dispatched.Enqueue(id);
     public void OnStub(int opcode) { }
 
     // ---- texture ops (run on the VM thread; marshal Godot node work to the main thread) ----

godot/Main.cs

@@ -75,9 +75,11 @@ public partial class Main : Godot.Control
 
         var userArgs = OS.GetCmdlineUserArgs();
         _selftest = System.Array.IndexOf(userArgs, "--selftest") >= 0;
+        string scene = "SC0000";                        // --scene <NAME>: which scene to play (default SC0000)
         var seeds = new List<(int Addr, long Val)>();   // --seed 0xADDR=VAL (repeatable) — initial global state
         for (int i = 0; i < userArgs.Length; i++)
         {
+            if (userArgs[i] == "--scene" && i + 1 < userArgs.Length) scene = userArgs[i + 1];
             if (userArgs[i] == "--shot" && i + 1 < userArgs.Length) _shotPath = userArgs[i + 1];
             if (userArgs[i] == "--shot-page" && i + 1 < userArgs.Length) int.TryParse(userArgs[i + 1], out _shotPage);
             if (userArgs[i] == "--seed" && i + 1 < userArgs.Length)
@@ -98,8 +100,8 @@ public partial class Main : Godot.Control
         Script script;
         IScriptProvider provider;
         if (_selftest) (script, provider) = BuildSelfTestScene(table);
-        else { script = Sys4Loader.Load(Paths.Scripts()["SC0000.BIN"], table); provider = Sys4ScriptProvider.Load(table); }
+        else { script = Sys4Loader.Load(Paths.Scripts()[scene.ToUpperInvariant() + ".BIN"], table); provider = Sys4ScriptProvider.Load(table); }
-        _host = new GodotAdvHost(this, ResourceMap.Load(), "SC0000");
+        _host = new GodotAdvHost(this, ResourceMap.Load(), scene);
         _vm = new VirtualMachine(script, table, _host, null, provider);
         foreach (var (addr, val) in seeds) _vm.Globals[addr] = val;   // seed initial state before running
         _ = Task.Run(() => { _vm.Run(); _done = true; });
@@ -122,6 +124,7 @@ public partial class Main : Godot.Control
                 var img = GetViewport().GetTexture().GetImage();
                 img.SavePng(_shotPath);
                 GD.Print($"SHOT saved page {_pageCount} -> {_shotPath}");
+                ReportSubroutines();
                 GetTree().Quit(0);
             }
             return;
@@ -129,6 +132,7 @@ public partial class Main : Godot.Control
         if (_done && !_ended)
         {
             _ended = true;
+            ReportSubroutines();
             ShowEnd();
             if (_selftest) RunSelfTest();
         }
@@ -195,6 +199,17 @@ public partial class Main : Godot.Control
     // + CallDeferred marshalling) drives the VM faithfully — i.e. produces the SAME output as a plain
     // in-process run of the identical scene. Full op handling is on (the synthetic scene includes a real
     // nested call-script); the expected value is computed live from a headless run, not a frozen golden.
+    // Reports (from the main thread) the call-scripts the VM executed as nested subroutines this run.
+    private void ReportSubroutines()
+    {
+        var ids = new List<long>();
+        while (_host.Dispatched.TryDequeue(out var id)) ids.Add(id);
+        if (ids.Count == 0) { GD.Print("[subroutines] none dispatched on this path"); return; }
+        var distinct = new List<string>();
+        foreach (var id in ids) { var h = "0x" + id.ToString("x"); if (!distinct.Contains(h)) distinct.Add(h); }
+        GD.Print($"[subroutines] {ids.Count} call-scripts executed as nested frames ({distinct.Count} distinct: {string.Join(", ", distinct)})");
+    }
+
     private void RunSelfTest()
     {
         var table = OpcodeTableJson.Load(Paths.OpcodesJson);