refactor(rectification): split the chat component into hooks, parameter functions and blocks

Move-only (TASK-rectification-code-split-20260926 T1/T4). No behavior, API,
copy, DB, Skill or scoring change.

- rectification-agentic-chat.tsx: 2043 -> 737 lines; component body
  1625 -> 630; useState 35 -> 12, useRef 16 -> 9, effects 9 -> 5,
  useCallback 12 -> 6.
- Snapshot sync -> hooks/use-rectification-case-snapshot.ts; board layout
  and live label clock -> two small hooks.
- send / submitStructuredChoice / acceptCandidate bodies ->
  lib/rectification-chat-{turn,choice,accept}-run.ts parameter functions
  (bodies verbatim, deps destructured to the same names); copy/regenerate,
  question repair, pure transcript and snapshot helpers and the per-render
  view derivation -> lib/rectification-chat-*.ts (no React hooks).
- Question-gap blocks and the read-only range line ->
  components/rectification-question-gap-notices.tsx.
- Dependency arrays kept exactly as before (lint warnings +3, listed in
  PROGRESS); no dep added to appease the linter.
- Tests: whole-source contracts read tests/rectification-chat-surface.ts
  (container + split files, like home-surface.ts); slices of moved code now
  call the extracted functions or render the extracted block, each with a
  原值/新值/原因 comment. New tests/rectification-growth-contract.test.ts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017eEAG8HD3mm8gsKXgk8uU8

frontend/tests/rectification-surface-contract.test.ts

@@ -3,9 +3,15 @@ import { readFileSync } from "node:fs";
 import test from "node:test";
 
 import { homeSurface as page } from "./home-surface.ts";
+import { createElement } from "react";
+import { renderToStaticMarkup } from "react-dom/server";
+import { rectificationChatSurface, readRectificationChatFile } from "./rectification-chat-surface.ts";
+import { RectificationQuestionGapNotices } from "../src/components/rectification-question-gap-notices.tsx";
+import { RECTIFICATION_QUESTION_PREPARING_LABEL } from "../src/lib/rectification-surface-state.ts";
 
 const read = (relativePath: string) => readFileSync(new URL(relativePath, import.meta.url), "utf8");
-const chat = read("../src/components/rectification-agentic-chat.tsx");
+// 原值: 读 rectification-agentic-chat.tsx 单文件。新值: rectificationChatSurface（容器 + 拆出的 hook / 参数函数 / 块，见 rectification-chat-surface.ts）。原因: TASK-rectification-code-split-20260926 只搬不改，整文件断言跟着代码走；切片断言另行改为调用函数。
+const chat = rectificationChatSurface;
 const messageEntry = read("../src/components/rectification-message-entry.tsx");
 const hook = read("../src/hooks/use-rectification-surface.ts");
 const sessions = read("../src/hooks/use-session-management.ts");
@@ -127,9 +133,31 @@ test("the question gap is a live row with retries, then a reload; it never tells
   assert.match(chat, /if \(value\) setQuestionRetryAttempts\(0\);/);
   assert.doesNotMatch(chat, /useEffect\(\(\) => \{\s*if \(currentQuestion !== null/);
   // In flow: the gap is the last entry of the transcript, after the message loop, before the saved-time line.
-  const gapIndex = chat.indexOf('{questionGap === "preparing" && (');
-  assert.ok(gapIndex > chat.indexOf("{messages.map((message) => {"));
-  assert.ok(gapIndex < chat.indexOf("{savedTime && savedStatus === \"confirmed\""));
+  // 原值: chat 源码里 `{questionGap === "preparing" && (` 位于 `{messages.map` 之后、`{savedTime && savedStatus === "confirmed"` 之前。
+  // 新值: 容器里 `<RectificationQuestionGapNotices` 位于同两个锚点之间；再真渲染该块，preparing 态出 live 行和准备文案。
+  // 原因: TASK-rectification-code-split-20260926 把缺题块抽成组件，渲染位置不变；渲染断言比源码顺序更强。
+  const container = readRectificationChatFile("../src/components/rectification-agentic-chat.tsx");
+  const gapIndex = container.indexOf("<RectificationQuestionGapNotices");
+  assert.ok(gapIndex > container.indexOf("{messages.map((message) => {"));
+  assert.ok(gapIndex < container.indexOf("{savedTime && savedStatus === \"confirmed\""));
+  const preparingHtml = renderToStaticMarkup(createElement(RectificationQuestionGapNotices, {
+    view: { showStandaloneQuestion: false, questionGap: "preparing", showSelectionCards: false, verifiedIdleCopy: null },
+    currentQuestion: null,
+    choiceCard: null,
+    choiceNonce: 0,
+    busy: false,
+    readonly: false,
+    snapshotFailure: null,
+    questionRepairAttempts: 0,
+    questionRepairing: false,
+    submitChoice() {},
+    submitStop() {},
+    async refetchQuestion() {},
+    async repairQuestion() {},
+  }));
+  assert.match(preparingHtml, /class="rectification-message-wrap rectification-message-entry rectification-question-gap"/);
+  assert.match(preparingHtml, /data-status="live"/);
+  assert.ok(preparingHtml.includes(RECTIFICATION_QUESTION_PREPARING_LABEL));
   assert.match(styles, /\.rectification-question-gap \{/);
 });