🧩 Refactor(Workflow): 统一分支模型为 List<BranchArm> 并安全化 NextBlock

- 新增 BranchArm 类型(位于 Contract 层),取代 CFGStatement/FlowControlStatement
  的 TrueBlockName/FalseBlockName/ToLoopCondReturnTo 三槽,改为通用 List<BranchArm>
- 消灭 BP2CFGConverter 的位置映射 hack(normalArms[0]→True/[1]→False),
  改为按输出 Pin 名直接写 Arm,N 路分支不再丢失
- 安全化 NextBlock:移除 BlockScriptExecutionGlobals 的 Set/Get 对 "NextBlock"
  的特判,新增 internal AdvanceTo,Branch/Loop/Flip/ToLoopCond 改用它
- 适配全部转换器(BS2CFG/CFG2BS/CFG2CS/CFGConditionDuplicator/Executor)与
  5 个控制流 builtin 描述符到 Arms 模型
- 新增整数索引 Switch 内置函数:Switch(selector, "default", "b0", "b1", ...),
  越界走 default;Arms 布局 [Default, 0, 1, ..., N-1]
- 修复 DataEdgeBuilder:ConditionPubVar 从硬编码 PinType.Boolean 改为首个
  非 Exec pin,使 Switch 的 Integer selector 正确连接(BS→BP→BS 往返修复)
- BlockScriptExecutor.Validate 改为遍历 Arms 校验,统一覆盖 Branch/Loop/Switch

Breaking Changes: CFGStatement/FlowControlStatement 字段迁移
(TrueBlockName/FalseBlockName/ToLoopCondReturnTo → Arms),编译期暴露,无静默风险

Author: StardustSeemsInk

KitX Clients/KitX Dashboard

@@ -20,10 +20,25 @@ public partial class BlockScriptExecutionGlobals
     // ─── 内置属性 ───────────────────────────────────────────────
 
     /// <summary>
-    /// NextBlock 内置变量 - 设置后执行器会跳转到指定块
+    /// NextBlock 内置变量 - 设置后执行器会跳转到指定块。
+    /// 这是控制流的唯一载体。普通 <c>Set/Get</c> 不再识别 "NextBlock" 这个名字,
+    /// 因此用户脚本无法通过变量赋值劫持控制流、绕过 Loop/Break 语义或 CFG 校验。
+    /// 仅两类调用方可写此属性:(1) 生成的 <c>RunAsync</c> 主干(G.NextBlock = ...)——
+    /// 它是可信基础设施,完全由 CFG2CSGenerator 按已校验的 CFG 产出;(2) 受信任的 flow
+    /// 函数(Branch/Loop/Switch/Flip/ToLoopCond),应优先通过 <see cref="AdvanceTo"/> 写入。
     /// </summary>
     public string? NextBlock { get; set; }
 
+    /// <summary>
+    /// 受信任的控制流改写入口。内置 flow 函数应通过此方法设置下一个块,
+    /// 而非直接写 <see cref="NextBlock"/>,以保持单一改写路径。
+    /// </summary>
+    internal string? AdvanceTo(string? blockName)
+    {
+        NextBlock = blockName;
+        return NextBlock;
+    }
+
     /// <summary>
     /// Number of blocks executed so far in the current run.
     /// </summary>
@@ -47,11 +62,11 @@ public BlockScriptExecutionGlobals(BlockScopeManager scopeManager, List<string>
 
     /// <summary>
     /// Gets a variable value dynamically (CSharpScript path).
+    /// "NextBlock" is no longer a recognised variable name — control flow is only mutated
+    /// via <see cref="AdvanceTo"/> by trusted flow functions.
     /// </summary>
     public dynamic Get(string name)
     {
-        if (name == "NextBlock")
-            return NextBlock!;
         if (_variables.TryGetValue(name, out var value))
             return value!;
         return _scopeManager.ResolveVariable(name)!;
@@ -62,8 +77,6 @@ public dynamic Get(string name)
     /// </summary>
     public T? Get<T>(string name)
     {
-        if (name == "NextBlock")
-            return (T?)(object?)NextBlock;
         if (_variables.TryGetValue(name, out var value))
             return (T?)value;
         return (T?)_scopeManager.ResolveVariable(name);
@@ -74,11 +87,6 @@ public dynamic Get(string name)
     /// </summary>
     public void Set(string name, object? value)
     {
-        if (name == "NextBlock")
-        {
-            NextBlock = value as string;
-            return;
-        }
         _variables[name] = value;
         _scopeManager.SetVariable(name, value, global: false);
         Debugger?.UpdateVariableSnapshot(GetAllVariables());
@@ -89,11 +97,6 @@ public void Set(string name, object? value)
     /// </summary>
     public void SetGlobalVariable(string name, object? value)
     {
-        if (name == "NextBlock")
-        {
-            NextBlock = value as string;
-            return;
-        }
         _variables[name] = value;
         _scopeManager.SetVariable(name, value, global: true);
         Debugger?.UpdateVariableSnapshot(GetAllVariables());

KitX Clients/KitX Workflow/KitX.Workflow/BlockScripting/BlockScriptExecutionGlobals.cs

@@ -273,38 +273,14 @@ public BlockScriptValidationResult Validate(BlockScript script)
             {
                 if (statement is FlowControlStatement flow)
                 {
-                    if (flow.ControlType == FlowControlType.Branch)
+                    // Validate every arm target exists. Works uniformly for Branch (True/False),
+                    // Loop (LoopBody/LoopEnd), ToLoopCond (Exec loopback) and Switch (Default/0/1/...).
+                    foreach (var arm in flow.Arms)
                     {
-                        if (!string.IsNullOrEmpty(flow.TrueBlockName) &&
-                            !allBlockNames.Contains(flow.TrueBlockName))
+                        if (!string.IsNullOrEmpty(arm.TargetBlockName) &&
+                            !allBlockNames.Contains(arm.TargetBlockName))
                         {
-                            result.AddError($"Block '{flow.TrueBlockName}' referenced in Branch at line {flow.LineNumber} does not exist");
-                        }
-                        if (!string.IsNullOrEmpty(flow.FalseBlockName) &&
-                            !allBlockNames.Contains(flow.FalseBlockName))
-                        {
-                            result.AddError($"Block '{flow.FalseBlockName}' referenced in Branch at line {flow.LineNumber} does not exist");
-                        }
-                    }
-                    else if (flow.ControlType == FlowControlType.Loop)
-                    {
-                        if (!string.IsNullOrEmpty(flow.TrueBlockName) &&
-                            !allBlockNames.Contains(flow.TrueBlockName))
-                        {
-                            result.AddError($"Block '{flow.TrueBlockName}' referenced in Loop at line {flow.LineNumber} does not exist");
-                        }
-                        if (!string.IsNullOrEmpty(flow.FalseBlockName) &&
-                            !allBlockNames.Contains(flow.FalseBlockName))
-                        {
-                            result.AddError($"Block '{flow.FalseBlockName}' referenced in Loop at line {flow.LineNumber} does not exist");
-                        }
-                    }
-                    else if (flow.ControlType == FlowControlType.ToLoopCond)
-                    {
-                        if (!string.IsNullOrEmpty(flow.ToLoopCondReturnTo) &&
-                            !allBlockNames.Contains(flow.ToLoopCondReturnTo))
-                        {
-                            result.AddError($"Block '{flow.ToLoopCondReturnTo}' referenced in ToLoopCond at line {flow.LineNumber} does not exist");
+                            result.AddError($"Block '{arm.TargetBlockName}' referenced in {flow.ControlType} (arm '{arm.PinName}') at line {flow.LineNumber} does not exist");
                         }
                     }
                 }

KitX Clients/KitX Workflow/KitX.Workflow/BlockScripting/BlockScriptExecutor.cs

@@ -31,13 +31,16 @@ public static class Pins
         public const string False = "False";
         public const string LoopBody = "LoopBody";
         public const string LoopEnd = "LoopEnd";
+        public const string Default = "Default";
+        public const string Selector = "Selector";
     }
 
     /// <summary>Built-in flow control and action function names</summary>
     public static class Functions
     {
         public const string Branch = "Branch";
         public const string Loop = "Loop";
+        public const string Switch = "Switch";
         public const string ToLoopCond = "ToLoopCond";
         public const string Break = "Break";
         public const string Print = "Print";

KitX Clients/KitX Workflow/KitX.Workflow/BlockScripting/BlockScriptWellKnown.cs

@@ -67,6 +67,26 @@ public interface IBuiltinFunctionDefinition
     /// <summary>输出引脚描述</summary>
     IReadOnlyList<PinDescriptor> OutputPins { get; }
 
+    /// <summary>
+    /// 输入侧变长端口配置。非 null 时,蓝图编辑器在该组最后一个输入端口被连接后,
+    /// 自动追加一个 <see cref="VariadicPinSpec.PinType"/> 类型的新输入端口。
+    /// 默认 null(非变长)。StringConcat 覆写为字符串变长输入。
+    /// </summary>
+    VariadicPinSpec? InputVariadic => null;
+
+    /// <summary>
+    /// 输出侧变长端口配置。非 null 时,蓝图编辑器在该组最后一个输出端口被连接后,
+    /// 自动追加一个新输出端口。默认 null(非变长)。Switch 覆写为执行流变长输出。
+    /// </summary>
+    VariadicPinSpec? OutputVariadic => null;
+
+    /// <summary>
+    /// 按本语句的实际情况返回输出 Pin 描述符。默认返回固定 <see cref="OutputPins"/>(旧行为)。
+    /// 变长输出节点(如 Switch,其输出 arm 数随语句而变)覆写此方法,按 <see cref="CFGStatement.Arms"/>
+    /// 数量动态生成 [Default, 0, 1, ..., N-1],使 BS→BP 导入时端口数与 arm 数匹配。
+    /// </summary>
+    IReadOnlyList<PinDescriptor> GetOutputPinsFor(CFGStatement stmt) => OutputPins;
+
     // ─── 解析（BlockScript → AST）─────────────────
 
     /// <summary>

KitX Clients/KitX Workflow/KitX.Workflow/BlockScripting/IBuiltinFunctionDefinition.cs

@@ -89,7 +89,9 @@ public BlueprintNode CreateBuiltinFunctionNode(string functionName)
         var descriptor = new NodeDescriptor(
             def.NodeWidth, def.NodeHeight,
             def.InputPins, def.OutputPins,
-            def.DisplayName
+            def.DisplayName,
+            def.InputVariadic,
+            def.OutputVariadic
         );
         node.SetDescriptor(descriptor);
 

KitX Clients/KitX Workflow/KitX.Workflow/Blueprint/NodeRegistry.cs

@@ -102,8 +102,7 @@ public partial class BlockScriptExecutionGlobals
         /// </summary>
         public string? Branch(bool condition, string trueBlock, string falseBlock)
         {
-            NextBlock = condition ? trueBlock : falseBlock;
-            return NextBlock;
+            return AdvanceTo(condition ? trueBlock : falseBlock);
         }
     }
 }

KitX Clients/KitX Workflow/KitX.Workflow/BuiltinFunctions/BranchFunction.cs

@@ -108,8 +108,7 @@ public partial class BlockScriptExecutionGlobals
         public string? Flip(string outputA, string outputB)
         {
             _flipCounter++;
-            NextBlock = (_flipCounter % 2 == 1) ? outputA : outputB;
-            return NextBlock;
+            return AdvanceTo((_flipCounter % 2 == 1) ? outputA : outputB);
         }
 
         /// <summary>

KitX Clients/KitX Workflow/KitX.Workflow/BuiltinFunctions/FlipFunction.cs

@@ -106,8 +106,7 @@ public partial class BlockScriptExecutionGlobals
         /// </summary>
         public string? Loop(bool condition, string trueBlock, string falseBlock)
         {
-            NextBlock = condition ? trueBlock : falseBlock;
-            return NextBlock;
+            return AdvanceTo(condition ? trueBlock : falseBlock);
         }
     }
 }

KitX Clients/KitX Workflow/KitX.Workflow/BuiltinFunctions/LoopFunction.cs

@@ -33,6 +33,13 @@ public class StringConcatFunction : IBuiltinFunctionDefinition
         new("Result", PinType.String, 40),
     ];
 
+    /// <summary>
+    /// Input-side variadic growth: when the last String input is connected, the editor
+    /// auto-appends a new "Input {N}" String pin. Declared here (on the descriptor) so the
+    /// editor's generic variadic logic handles it instead of the former StringConcat name match.
+    /// </summary>
+    public VariadicPinSpec? InputVariadic => new("Input ", 3, PinType.String);
+
     public BlockStatement? ExtractStatement(InvocationExpressionSyntax invoke, int lineNumber, string? exprText) => null;
 
     public List<StatementSyntax> EmitStatements(CFGStatement stmt, CSEmitContext ctx)