Refactor workflow routing and greeting management in Brain classes

- Update WorkflowBrain to handle greeting playback more effectively, ensuring that the initial greeting completes before transitioning to the first node.
- Introduce new methods for managing greeting states and conditions, enhancing the interaction flow for user turns.
- Refactor WorkflowLLMRouter to improve routing logic and ensure proper handling of conditional paths.
- Enhance tests to verify the correct behavior of greeting management and routing under various scenarios, including waiting for audio playback to finish.
- Update frontend components to reflect changes in edge handling and improve user experience in workflow configurations.

frontend/src/components/workflow/panels/EdgeSettingsPanel.tsx

@@ -27,11 +27,11 @@ import type { ExpressionRule, WorkflowEdgeData } from "../specs";
 
 export function EdgeSettingsPanel({
   edge,
-  sourceType,
+  hasOtherDefaultPath,
   onChange,
 }: {
   edge: Edge;
-  sourceType?: string;
+  hasOtherDefaultPath: boolean;
   onChange: (patch: WorkflowEdgeData) => void;
 }) {
   const data = (edge.data ?? { mode: "always", priority: 10 }) as WorkflowEdgeData;
@@ -100,15 +100,19 @@ export function EdgeSettingsPanel({
       <SectionCard
         icon={<GitBranch size={15} />}
         title="路由方式"
-        description="选择由 Agent 判断、动态变量表达式判断，或作为确定性默认路径"
+        description="每个节点最多一条默认路径，也可以配置多条条件路径"
       >
         <NodeSelect
-          label="判断方式"
+          label="条件类型"
           value={mode}
           options={[
-            ...(sourceType === "agent" ? [{ value: "llm", label: "LLM 判断" }] : []),
-            { value: "expression", label: "动态变量表达式" },
-            { value: "always", label: "默认路径" },
+            {
+              value: "always",
+              label: "默认路径",
+              disabled: mode !== "always" && hasOtherDefaultPath,
+            },
+            { value: "llm", label: "大模型判断" },
+            { value: "expression", label: "表达式" },
           ]}
           onChange={(value) => {
             const nextMode =
@@ -118,6 +122,11 @@ export function EdgeSettingsPanel({
           }}
           allowNone={false}
         />
+        {mode !== "always" && hasOtherDefaultPath && (
+          <span className="-mt-1 block text-xs text-muted-foreground">
+            当前节点已经有一条默认路径；其它出边需要使用大模型判断或表达式。
+          </span>
+        )}
         <label className="block">
           <div className="mb-1.5 text-sm font-medium text-foreground">
             优先级
@@ -133,7 +142,7 @@ export function EdgeSettingsPanel({
             className="border-hairline-strong bg-background text-foreground"
           />
           <span className="mt-1.5 block text-xs text-muted-foreground">
-            同一节点的边按数字从小到大依次判断。
+            条件路径按数字从小到大判断，默认路径始终作为兜底。
           </span>
         </label>
       </SectionCard>
@@ -333,5 +342,3 @@ export function EdgeSettingsPanel({
     </div>
   );
 }
-
-

frontend/src/components/workflow/panels/controls.tsx

@@ -201,7 +201,11 @@ export function NodeSelect({
         <SelectContent className="border-hairline bg-popover text-popover-foreground">
           {allowNone && <SelectItem value={NONE}>{noneLabel}</SelectItem>}
           {options.map((option) => (
-            <SelectItem key={option.value} value={option.value}>
+            <SelectItem
+              key={option.value}
+              value={option.value}
+              disabled={option.disabled}
+            >
               {option.label}
             </SelectItem>
           ))}
@@ -211,4 +215,3 @@ export function NodeSelect({
   );
 }
 
-