Enhance workflow routing and agent configuration management

- Introduce WorkflowLLMRouter for pre-response LLM routing, allowing agents to determine the appropriate function to call based on user input.
- Implement UserTurnRoutingProcessor to manage user turns before reaching the LLM, ensuring proper routing and handling of user messages.
- Refactor WorkflowBrain to integrate new routing logic and enhance agent stage configuration, including entry modes and resource management.
- Update service factory to support dynamic LLM resource configuration based on workflow settings.
- Add tests for new routing functionality and ensure proper handling of user messages in various scenarios.

frontend/src/components/editor/knowledge-retrieval-config-dialog.tsx

@@ -0,0 +1,168 @@
+"use client";
+
+import { Settings2 } from "lucide-react";
+import { useState } from "react";
+
+import { Button } from "@/components/ui/button";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/ui/dialog";
+import { Input } from "@/components/ui/input";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
+import type { KnowledgeRetrievalConfig } from "@/lib/api";
+
+export const DEFAULT_KNOWLEDGE_RETRIEVAL_CONFIG: KnowledgeRetrievalConfig = {
+  mode: "automatic",
+  topN: 5,
+  scoreThreshold: 0,
+};
+
+export function KnowledgeRetrievalConfigDialog({
+  disabled,
+  value,
+  onChange,
+}: {
+  disabled: boolean;
+  value: KnowledgeRetrievalConfig;
+  onChange: (config: KnowledgeRetrievalConfig) => void;
+}) {
+  const [open, setOpen] = useState(false);
+  const [draft, setDraft] = useState(value);
+  const [error, setError] = useState<string | null>(null);
+
+  function openDialog() {
+    setDraft(value);
+    setError(null);
+    setOpen(true);
+  }
+
+  function saveDraft() {
+    if (draft.topN === 0 || draft.topN < -1 || !Number.isInteger(draft.topN)) {
+      setError("Top N 必须为 -1 或大于 0 的整数");
+      return;
+    }
+    if (draft.scoreThreshold < 0 || draft.scoreThreshold > 1) {
+      setError("最低相关度必须在 0 到 1 之间");
+      return;
+    }
+    onChange(draft);
+    setOpen(false);
+  }
+
+  return (
+    <>
+      <button
+        type="button"
+        disabled={disabled}
+        onClick={openDialog}
+        aria-label="打开知识库高级配置"
+        title={
+          disabled
+            ? "请先选择知识库"
+            : `${value.mode === "automatic" ? "自动检索" : "模型主动检索"} · Top N ${value.topN === -1 ? "不限" : value.topN} · 最低相关度 ${value.scoreThreshold}`
+        }
+        className="flex h-5 w-5 items-center justify-center rounded-full text-muted-soft transition-colors hover:bg-surface-strong hover:text-foreground disabled:cursor-not-allowed disabled:opacity-40"
+      >
+        <Settings2 size={14} />
+      </button>
+
+      <Dialog open={open} onOpenChange={setOpen}>
+        <DialogContent className="sm:max-w-lg">
+          <DialogHeader>
+            <DialogTitle>知识库高级配置</DialogTitle>
+            <DialogDescription>
+              设置检索触发方式、返回数量和相关度过滤条件。
+            </DialogDescription>
+          </DialogHeader>
+
+          <div className="space-y-5 py-2">
+            <div className="space-y-2">
+              <div className="text-sm font-medium text-foreground">检索方式</div>
+              <Select
+                value={draft.mode}
+                onValueChange={(mode: "automatic" | "on_demand") =>
+                  setDraft({ ...draft, mode })
+                }
+              >
+                <SelectTrigger className="w-full border-hairline-strong bg-background">
+                  <SelectValue />
+                </SelectTrigger>
+                <SelectContent>
+                  <SelectItem value="automatic">自动检索</SelectItem>
+                  <SelectItem value="on_demand">模型主动检索</SelectItem>
+                </SelectContent>
+              </Select>
+              <p className="text-xs text-muted-foreground">
+                {draft.mode === "automatic"
+                  ? "每轮用户提问后自动检索，响应行为更稳定。"
+                  : "由大模型判断是否调用知识库，依赖模型的工具调用能力。"}
+              </p>
+            </div>
+
+            <label className="block">
+              <span className="mb-2 block text-sm font-medium text-foreground">
+                最多返回片段数
+              </span>
+              <Input
+                type="number"
+                step="1"
+                min="-1"
+                value={draft.topN}
+                onChange={(event) =>
+                  setDraft({ ...draft, topN: Number(event.target.value) })
+                }
+              />
+              <span className="mt-1.5 block text-xs text-muted-foreground">
+                填写 -1 时保留所有达到阈值的结果。
+              </span>
+            </label>
+
+            <label className="block">
+              <span className="mb-2 block text-sm font-medium text-foreground">
+                最低相关度
+              </span>
+              <Input
+                type="number"
+                step="0.01"
+                min="0"
+                max="1"
+                value={draft.scoreThreshold}
+                onChange={(event) =>
+                  setDraft({
+                    ...draft,
+                    scoreThreshold: Number(event.target.value),
+                  })
+                }
+              />
+              <span className="mt-1.5 block text-xs text-muted-foreground">
+                仅保留相关度达到该值的片段，范围 0–1。
+              </span>
+            </label>
+
+            {error && <p className="text-sm text-destructive">{error}</p>}
+          </div>
+
+          <DialogFooter>
+            <Button type="button" variant="outline" onClick={() => setOpen(false)}>
+              取消
+            </Button>
+            <Button type="button" onClick={saveDraft}>
+              保存配置
+            </Button>
+          </DialogFooter>
+        </DialogContent>
+      </Dialog>
+    </>
+  );
+}