Add Dify integration and enhance workflow node specifications

- Introduce new fields `dify_api_url` and `dify_api_key` in `AssistantConfig` for Dify API integration.
- Update `requirements.txt` to include `dify-client-python` for Dify SDK support.
- Modify `config_resolver` to handle Dify connection information.
- Add a new `globalNode` type in workflow specifications to provide unified settings across workflows.
- Enhance node specifications with additional constraints and default values for better configuration management.
- Update frontend components to support the new `globalNode` type and its properties, improving workflow editor functionality.

backend/services/node_specs.py

@@ -1,6 +1,6 @@
 """工作流节点规格 + 图校验(对齐 dograh 的 node-spec / GraphConstraints 思路)。
 
-当前实现 3 个核心节点:开始(startCall)/智能体(agentNode)/结束(endCall)。
+当前实现 4 个核心节点:开始(startCall)/智能体(agentNode)/结束(endCall)/全局(globalNode)。
 本模块是「节点类型」的唯一事实源:
   - /api/node-types 接口直接吐这里的规格;
   - 助手保存时用这里的约束校验 workflow 图。
@@ -13,7 +13,7 @@ from __future__ import annotations
 from typing import Any
 
 # 规格版本号:节点定义有破坏性变更时 +1,前端可据此判断是否需要刷新缓存。
-SPEC_VERSION = "1"
+SPEC_VERSION = "2"
 
 # 每个节点的图约束。None 表示不限制。
 #   min_incoming / max_incoming:入边数量
@@ -27,11 +27,28 @@ NODE_SPECS: list[dict[str, Any]] = [
         "icon": "Play",
         "accent": "mint",
         "addable": False,
-        "constraints": {"minIncoming": 0, "maxIncoming": 0},
+        "constraints": {
+            "minIncoming": 0,
+            "maxIncoming": 0,
+            "minInstances": 1,
+            "maxInstances": 1,
+        },
         "fields": [
-            {"key": "name", "label": "节点名称", "type": "text"},
-            {"key": "greeting", "label": "开场白", "type": "textarea"},
-            {"key": "prompt", "label": "节点提示词", "type": "textarea"},
+            {"key": "name", "label": "节点名称", "type": "text", "default": "开始"},
+            {"key": "greeting", "label": "开场白", "type": "textarea", "default": ""},
+            {"key": "prompt", "label": "节点提示词", "type": "textarea", "default": ""},
+            {
+                "key": "allowInterrupt",
+                "label": "允许用户打断",
+                "type": "switch",
+                "default": True,
+            },
+            {
+                "key": "addGlobalPrompt",
+                "label": "应用全局提示词",
+                "type": "switch",
+                "default": True,
+            },
         ],
     },
     {
@@ -44,9 +61,26 @@ NODE_SPECS: list[dict[str, Any]] = [
         "addable": True,
         "constraints": {"minIncoming": 1},
         "fields": [
-            {"key": "name", "label": "节点名称", "type": "text"},
-            {"key": "prompt", "label": "节点提示词", "type": "textarea", "required": True},
-            {"key": "allowInterrupt", "label": "允许用户打断", "type": "switch"},
+            {"key": "name", "label": "节点名称", "type": "text", "default": "智能体节点"},
+            {
+                "key": "prompt",
+                "label": "节点提示词",
+                "type": "textarea",
+                "required": True,
+                "default": "",
+            },
+            {
+                "key": "allowInterrupt",
+                "label": "允许用户打断",
+                "type": "switch",
+                "default": True,
+            },
+            {
+                "key": "addGlobalPrompt",
+                "label": "应用全局提示词",
+                "type": "switch",
+                "default": True,
+            },
         ],
     },
     {
@@ -59,8 +93,40 @@ NODE_SPECS: list[dict[str, Any]] = [
         "addable": True,
         "constraints": {"minIncoming": 1, "minOutgoing": 0, "maxOutgoing": 0},
         "fields": [
-            {"key": "name", "label": "节点名称", "type": "text"},
-            {"key": "prompt", "label": "结束语提示词", "type": "textarea"},
+            {"key": "name", "label": "节点名称", "type": "text", "default": "结束"},
+            {"key": "prompt", "label": "结束语提示词", "type": "textarea", "default": ""},
+            {
+                "key": "addGlobalPrompt",
+                "label": "应用全局提示词",
+                "type": "switch",
+                "default": False,
+            },
+        ],
+    },
+    {
+        "name": "globalNode",
+        "displayName": "全局节点",
+        "category": "global_node",
+        "description": "为整个工作流提供统一的人设、语气和公共规则。无需连线,每个流程最多一个。",
+        "icon": "Globe2",
+        "accent": "lavender",
+        "addable": True,
+        "constraints": {
+            "minIncoming": 0,
+            "maxIncoming": 0,
+            "minOutgoing": 0,
+            "maxOutgoing": 0,
+            "maxInstances": 1,
+        },
+        "fields": [
+            {"key": "name", "label": "节点名称", "type": "text", "default": "全局设定"},
+            {
+                "key": "prompt",
+                "label": "全局提示词",
+                "type": "textarea",
+                "required": True,
+                "default": "你是一个友好、专业的语音助手。请使用简短、自然、适合口语表达的句子。",
+            },
         ],
     },
 ]
@@ -79,7 +145,7 @@ def validate_graph(graph: dict[str, Any]) -> list[str]:
     基础规则(对齐 dograh 的核心不变量):
       1. 节点类型必须是已注册类型;
       2. 有且仅有一个 startCall;
-      3. 至少有一个 endCall;
+      3. 至少有一个 endCall,全局节点最多一个;
       4. 边的 source/target 必须指向存在的节点;
       5. 入边/出边数量满足各节点类型的约束。
 
@@ -120,6 +186,21 @@ def validate_graph(graph: dict[str, Any]) -> list[str]:
     if type_counts.get("endCall", 0) == 0:
         errors.append("工作流至少需要一个「结束」节点")
 
+    for node_type, spec in _SPEC_BY_NAME.items():
+        # 开始节点上方已有更明确的中文错误提示,避免重复报错。
+        if node_type == "startCall":
+            continue
+        constraints = spec["constraints"]
+        count = type_counts.get(node_type, 0)
+        _check_count(
+            errors,
+            count,
+            constraints,
+            "Instances",
+            node_type,
+            "实例",
+        )
+
     # 统计入边/出边
     incoming: dict[str, int] = {nid: 0 for nid in node_ids}
     outgoing: dict[str, int] = {nid: 0 for nid in node_ids}