fix(knowledge-fs): constrain research graph planning

api/knowledge-fs-contract.lock.json

@@ -1,6 +1,6 @@
 {
   "schemaVersion": 5,
-  "subtreeTree": "0739e3faf3861c45e78beb693edcd7e9d6550c1f",
+  "subtreeTree": "cd6c4687eaafa5e178c79aaa52c88869666f36b4",
   "openapiSha256": "2cf348c68bbe65dd51bbde9a0a4f91398beeebd79e89e9288c9386b26ae09796",
   "capabilityV2AuthManifestSha256": "fc0a47e23cce12544882f0298522b4933002e892b84ce1815df7e81d36a7a0c7",
   "capabilityV2AuthTestVectorSha256": "ae0de37b1ff05c40f905cf17a7b410d8971acacf64db07d5ee3d6fecfa559ce3",

knowledge-fs/packages/api/src/research-evidence-reasoning.test.ts

@@ -83,11 +83,23 @@ describe("Research evidence reasoning", () => {
       subqueries: ["renewal terms", "termination terms"],
     });
     expect(generate).toHaveBeenCalledTimes(2);
+    expect(generate.mock.calls[1]?.[0]).toMatchObject({
+      structuredOutputSchema: {
+        properties: {
+          useGraph: { enum: ["false", "true"], type: "string" },
+        },
+      },
+    });
   });
 
   it.each([
     { expected: false, providerValue: "false" },
+    {
+      expected: false,
+      providerValue: "不使用；这是按主题拆分的概览检索，不需要关系图或多跳推理。",
+    },
     { expected: true, providerValue: "true" },
+    { expected: true, providerValue: "需要使用关系图完成多跳推理。" },
   ])(
     "normalizes the structured-output string boolean useGraph=$providerValue",
     async ({ expected, providerValue }) => {

knowledge-fs/packages/api/src/research-evidence-reasoning.ts

@@ -403,7 +403,9 @@ function zodJsonSchema(schema: z.ZodTypeAny): Readonly<Record<string, unknown>>
         evidenceDimensions: { items: { type: "string" }, maxItems: 6, type: "array" },
         intent: { enum: ["comparison", "direct", "multi-hop", "overview"], type: "string" },
         subqueries: { items: { type: "string" }, maxItems: 3, type: "array" },
-        useGraph: { type: "boolean" },
+        // Dify's structured-output compatibility layer converts JSON Schema booleans to strings.
+        // Constrain the string values here so the model cannot replace a boolean with prose.
+        useGraph: { enum: ["false", "true"], type: "string" },
       },
       required: ["evidenceDimensions", "intent", "subqueries", "useGraph"],
       type: "object",
@@ -444,7 +446,7 @@ function parseQueryPlan(text: string): z.infer<typeof QueryPlanSchema> {
     // Dify's structured-output compatibility layer represents JSON Schema booleans as strings
     // for providers that do not accept native boolean fields. Normalize that transport detail
     // before applying the strict domain schema, just as the evidence judge does below.
-    const useGraph = normalizeBooleanValue(record.useGraph);
+    const useGraph = normalizeUseGraphValue(record.useGraph);
     if (useGraph !== undefined) {
       value = { ...record, useGraph };
     }
@@ -542,6 +544,29 @@ function normalizeBooleanValue(value: unknown): boolean | undefined {
   return undefined;
 }
 
+function normalizeUseGraphValue(value: unknown): boolean | undefined {
+  const normalizedBoolean = normalizeBooleanValue(value);
+  if (normalizedBoolean !== undefined || typeof value !== "string") {
+    return normalizedBoolean;
+  }
+  const normalized = value.trim().toLocaleLowerCase();
+  if (
+    /^(?:do not use|don't use|not needed|unnecessary|不使用|不要使用|无需|不需要|不启用)(?:\s|关系图|图谱|图|[.,，。:：;；]|$)/u.test(
+      normalized,
+    )
+  ) {
+    return false;
+  }
+  if (
+    /^(?:use|should use|need to use|enabled|使用|应使用|需要使用|启用|开启)(?:\s|关系图|图谱|图|[.,，。:：;；]|$)/u.test(
+      normalized,
+    )
+  ) {
+    return true;
+  }
+  return undefined;
+}
+
 function modelFailureIsRetryable(error: unknown): boolean {
   if (error && typeof error === "object" && "retryable" in error) {
     return (error as { readonly retryable?: unknown }).retryable === true;