refactor(home): 校正面 15 个状态从 Home 下沉

Home() useState 66->52, useRef 41->39. Shell-facing fields merge into one object;
subtree state lives in useRectificationSurface. Chat props 20->7. Growth contract
rebaselined. Zero behavior/copy change.

frontend/src/app/page.tsx

@@ -21,13 +21,11 @@ import {
   entrySummaryFromResponse,
   rectificationEntryLabels,
   resolveRectificationEntryAction,
-  type RectificationEntrySummary,
 } from "@/lib/rectification-entry";
-import { ConversationalBirthTimeRectification, type PersistedRectificationTurn } from "@/components/conversational-birth-time-rectification";
+import { ConversationalBirthTimeRectification } from "@/components/conversational-birth-time-rectification";
 import {
   declaredBirthTime,
   RECTIFICATION_OPENING_LABEL,
-  type RectificationCaseSnapshotPayload,
 } from "@/lib/rectification-surface-state";
 import {
   toggleChatMessageFeedback,
@@ -72,7 +70,11 @@ import { useBirthTimeGuidedJourney } from "@/hooks/use-birth-time-guided-journey
 import { useConsultationRun } from "@/hooks/use-consultation-run";
 import { useConversationScrollAnchor } from "@/hooks/use-conversation-scroll-anchor";
 import { useProfileOnboarding } from "@/hooks/use-profile-onboarding";
-import { useRectificationSurface } from "@/hooks/use-rectification-surface";
+import {
+  createRectificationShellSetters,
+  EMPTY_RECTIFICATION_SHELL,
+  useRectificationSurface,
+} from "@/hooks/use-rectification-surface";
 import { useSessionManagement } from "@/hooks/use-session-management";
 import { sortSessions } from "@/lib/session-groups";
 import { showChatNotice as setComposerNotice } from "@/lib/chat-notice";
@@ -282,23 +284,26 @@ export default function Home() {
   const [birthTimeConsultationConsent, setBirthTimeConsultationConsent] = useState<BirthTimeConsultationConsentState>(
     createBirthTimeConsultationConsentState,
   );
-  const [rectificationSessionId, setRectificationSessionId] = useState<string | null>(null);
-  const [rectificationCaseId, setRectificationCaseId] = useState<string | null>(null);
-  const [rectificationHeaderSlot, setRectificationHeaderSlot] = useState<HTMLElement | null>(null);
-  const [rectificationPendingQuestion, setRectificationPendingQuestion] = useState<string | null>(null);
-  const [rectificationLoading, setRectificationLoading] = useState(false);
-  const [rectificationMutationPending, setRectificationMutationPending] = useState(false);
-  const [rectificationError, setRectificationError] = useState("");
-  const [rectificationErrorSessionId, setRectificationErrorSessionId] = useState<string | null>(null);
-  const [rectificationReadonly, setRectificationReadonly] = useState(false);
-  const [rectificationShouldStartOpening, setRectificationShouldStartOpening] = useState(false);
-  const [rectificationTurns, setRectificationTurns] = useState<PersistedRectificationTurn[]>([]);
-  const [rectificationSnapshot, setRectificationSnapshot] = useState<RectificationCaseSnapshotPayload | null>(null);
-  const [rectificationOpeningSessionId, setRectificationOpeningSessionId] = useState<string | null>(null);
-  const [rectificationEntrySummary, setRectificationEntrySummary] = useState<RectificationEntrySummary | null>(null);
+  const [rectification, setRectification] = useState(EMPTY_RECTIFICATION_SHELL);
+  const {
+    sessionId: rectificationSessionId,
+    caseId: rectificationCaseId,
+    openingSessionId: rectificationOpeningSessionId,
+    loading: rectificationLoading,
+    mutationPending: rectificationMutationPending,
+    entrySummary: rectificationEntrySummary,
+    entrySummarySettled: rectificationEntrySummarySettled,
+    error: rectificationError,
+    errorSessionId: rectificationErrorSessionId,
+  } = rectification;
+  const {
+    setRectificationError,
+    setRectificationErrorSessionId,
+    setRectificationEntrySummary,
+    setRectificationEntrySummarySettled,
+  } = createRectificationShellSetters(setRectification);
   const [hydrated, setHydrated] = useState(false);
   const [bootstrapPhase, setBootstrapPhase] = useState<BootstrapPhase>("account");
-  const [rectificationEntrySummarySettled, setRectificationEntrySummarySettled] = useState(false);
   const prepareStartedAt = useRef<number | null>(null);
   const [guidedJourneyPreview, setGuidedJourneyPreview] = useState(false);
   const [profileSaving, setProfileSaving] = useState(false);
@@ -347,8 +352,6 @@ export default function Home() {
     onFollowUp() {},
   });
   const accountRefreshGuard = useRef(createLatestAccountRequestGuard());
-  const resumeRectificationSession = useRef<(session: ChatSession) => void>(() => undefined);
-  const rectificationOpenInFlight = useRef(false);
   const sessionDetailInFlight = useRef(new Set<string>());
   const sessionsRef = useRef(sessions);
   const rectificationSessionOpenerRef = useRef(async (_exactSessionId: string) => {});
@@ -465,21 +468,15 @@ export default function Home() {
   });
 
   const {
-    refreshRectificationCase,
+    setRectificationHeaderSlot,
+    rectificationPanel,
+    resumeRectificationSession,
     openRectificationFromHomepage,
-    startNewRectification,
-    handleRectificationProfileIncomplete,
-    handleRectificationMessagesChange,
   } = useRectificationSurface({
     account, activeChartId, activeSessionIdRef, chartLibrary, creatingSession, modelCatalog,
-    persistSession, profile, rectificationLoading, rectificationMutationPending,
-    rectificationOpenInFlight, rectificationSessionId, resumeRectificationSession,
+    persistSession, profile, rectification, setRectification,
     sessionSelectionSource, sessions, setActiveSessionId, setDraft, setDraftEntrypoint,
-    setDraftTheme, setOnboardingStep, setProfileNotice, setRectificationCaseId,
-    setRectificationEntrySummary, setRectificationError, setRectificationErrorSessionId, setRectificationLoading,
-    setRectificationPendingQuestion, setRectificationReadonly, setRectificationSessionId,
-    setRectificationShouldStartOpening, setRectificationSnapshot, setRectificationOpeningSessionId,
-    setRectificationTurns, setSessions, uiPreview,
+    setDraftTheme, setOnboardingStep, setProfileNotice, setSessions, uiPreview,
     updateSession, openAccountDialog, refreshAccount, rectificationSessionOpenerRef,
   });
 
@@ -540,6 +537,7 @@ export default function Home() {
     rectificationLoading,
     rectificationMutationPending,
     rectificationSessionId,
+    resumeRectificationSession,
   ]);
 
   useEffect(() => {
@@ -1855,31 +1853,13 @@ export default function Home() {
         {rectificationSurfaceOpen && rectificationCaseId && (
           <ConversationalBirthTimeRectification
             key={`${rectificationSessionId}-${rectificationCaseId}`}
-            caseId={rectificationCaseId}
-            sessionId={rectificationSessionId ?? ""}
-            readonly={rectificationReadonly}
-            shouldStartOpening={rectificationShouldStartOpening}
-            initialTurns={rectificationTurns}
-            initialSnapshot={rectificationSnapshot}
             declaredTime={rectificationDeclaredTime}
             models={modelCatalog?.models ?? []}
             selectedModelId={activeSession?.modelId ?? ""}
             onSelectModel={(modelId) => void selectSessionModel(modelId)}
-            onMessagesChange={handleRectificationMessagesChange}
-            onOpeningConsumed={() => setRectificationShouldStartOpening(false)}
-            onCompleted={() => {
-              void refreshAccount();
-              if (rectificationCaseId && rectificationSessionId) {
-                void refreshRectificationCase(rectificationCaseId, rectificationSessionId);
-              }
-            }}
-            onPendingChange={setRectificationMutationPending}
-            onProfileIncomplete={handleRectificationProfileIncomplete}
             onOpenBilling={(options) => openAccountDialog("billing", { source: options?.source ?? "rectification" })}
             onSaved={() => void refreshAccount()}
-            pendingConsultationQuestion={rectificationPendingQuestion}
-            onRestart={() => void startNewRectification()}
-            headerSlot={rectificationHeaderSlot}
+            panel={rectificationPanel}
           />
         )}