refactor: unify tool reason requirements

tests/routes/toolReason.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from "bun:test";
+import { buildToolProgressDetail, extractRequestReason } from "../../src/routes/chatStreamEvents.js";
+
+describe("tool reason display", () => {
+  it("omits absent explanations and displays canonical or legacy reasons once", () => {
+    const plain = buildToolProgressDetail("query", "running", { id: "n1" }, "");
+    expect(plain).not.toContain("说明：");
+    expect(plain).not.toContain("原因：");
+    expect(plain).toContain("id=n1");
+    for (const input of [{ reason: "  核验压力异常  " }, { request_reason: "核验压力异常" }]) {
+      const detail = buildToolProgressDetail("query", "running", input, extractRequestReason(input));
+      expect(detail).toContain("；说明：核验压力异常");
+      expect(detail.match(/核验压力异常/g)).toHaveLength(1);
+    }
+    expect(extractRequestReason({ reason: "当前说明", purpose: "旧说明" })).toBe("当前说明");
+  });
+});