fix(rectification): invite-first collect, holdout at 4 events, Skill 10.0.23 (BUG-646–648)

Stop domain-wheel collecting and age-band years in prompts. Ask until the training gate, then discriminate until convergence, then deliver a range plus a concrete follow-up. Reserve holdout only with four dated events.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/tests/rectification-split-holdout.test.ts

@@ -1,7 +1,7 @@
 import assert from "node:assert/strict";
 import test from "node:test";
 
-import { holdoutEventIds, splitHoldoutEvents } from "../src/lib/rectification-agentic/core/split-holdout.ts";
+import { holdoutEventIds, holdoutReservationStatus, splitHoldoutEvents } from "../src/lib/rectification-agentic/core/split-holdout.ts";
 
 test("holdout fallback reserves a month-or-better event, not a trailing year event", () => {
   const events = splitHoldoutEvents([
@@ -24,3 +24,17 @@ test("singleton-domain holdout still prefers that domain when training would sta
   ]);
   assert.deepEqual([...holdoutEventIds(events)], ["edu"]);
 });
+
+test("three dated events stay in training and do not reserve a holdout", () => {
+  const events = splitHoldoutEvents([
+    { id: "edu", domain: "education", year: 2016, precision: "month" },
+    { id: "job", domain: "career", year: 2018, precision: "month" },
+    { id: "love", domain: "relationship", year: 2021, precision: "year" },
+  ]);
+  // 原值: 3 件留 1 件 holdout，训练只剩 2，训练门关
+  // 新值: 不足 4 件不留 holdout，3 件全进训练
+  // 原因: 用户给了门槛件数却被 holdout 卡住（BUG-647）
+  assert.equal(holdoutEventIds(events).size, 0);
+  assert.equal(events.filter((item) => item.usage === "training").length, 3);
+  assert.equal(holdoutReservationStatus(events), "not_reserved_min_events");
+});