Preserve contextual back navigation and recent answers

docs/design-system/adoption-manifest.json

@@ -250,7 +250,11 @@
         "preview": ".design-sync/previews/Breadcrumb.tsx",
         "previewValid": true
       },
-      "testFiles": ["tests/design-sync-visual-exports.test.ts", "tests/information-page-shell.dom.test.tsx"],
+      "testFiles": [
+        "tests/design-sync-visual-exports.test.ts",
+        "tests/in-page-nav-playwright-contract.test.ts",
+        "tests/information-page-shell.dom.test.tsx"
+      ],
       "baseline": {
         "targetLayer": "v2",
         "liveLayer": "v2",

src/app/privacy/page.tsx

@@ -43,7 +43,9 @@ const SECTIONS: Section[] = [
       <>
         Raw question text is not written to query logs by default; logs use a keyed one-way hash. Generated answer text
         is also omitted from durable query logs by default. A short-lived response cache can contain the answer while
-        its read TTL is valid.
+        its read TTL is valid. To make recent answers reappear quickly, completed answer threads may also remain in this
+        browser tab for up to 12 hours. That tab-only copy stays in this tab, is not shared across tabs or devices, and
+        is never sent to the application service.
       </>
     ),
   },
@@ -64,7 +66,7 @@ const SECTIONS: Section[] = [
   },
   {
     heading: "Retention",
-    body: "Repository migrations configure 30-day retention for RAG query records, 90-day retention for retrieval logs and query-miss telemetry, and a bounded hourly purge of expired response-cache rows when the database scheduler is available. The operator must verify that those scheduled jobs are active. Uploaded documents remain until removed under the applicable process. Safety-plan working content has no Clinical KB retention: it is discarded when the component is cleared or the tab is closed. Clipboard, print, and PDF copies are outside the app and must follow the organisation's approved record-handling process.",
+    body: "Repository migrations configure 30-day retention for RAG query records, 90-day retention for retrieval logs and query-miss telemetry, and a bounded hourly purge of expired response-cache rows when the database scheduler is available. The operator must verify that those scheduled jobs are active. Uploaded documents remain until removed under the applicable process. Completed answer threads in the current browser tab expire no later than 12 hours after the most recent answer and are also cleared by New chat, sign-out, or an account change. Safety-plan working content has no Clinical KB retention: it is discarded when the component is cleared or the tab is closed. Clipboard, print, and PDF copies are outside the app and must follow the organisation's approved record-handling process.",
   },
   {
     heading: "Your responsibilities",

src/components/ClinicalDashboard.tsx

@@ -157,7 +157,7 @@ import {
   UploadPanel,
 } from "@/components/clinical-dashboard/clinical-dashboard-lazy";
 
-import { clearLegacyRecentQueries, demoRecentQueryOwnerId, recentQueryStorageKey } from "@/lib/recent-query-storage";
+import { clearLegacyRecentQueries, recentQueryStorageKey } from "@/lib/recent-query-storage";
 import type { SearchFacets } from "@/components/clinical-dashboard/document-search-results";
 import { isWeakRelevance } from "@/components/clinical-dashboard/relevance";
 import {
@@ -212,10 +212,15 @@ import { useDeferredRegistrySearch } from "@/components/clinical-dashboard/use-d
 import { buildAnswerFollowUpQuery, buildAnswerFollowUpSuggestions } from "@/lib/answer-follow-up";
 import {
   clearPersistedAnswerThread,
-  loadPersistedAnswerThread,
+  createAnswerThreadSnapshotMetadata,
   maxStoredAnswerTurns,
-  savePersistedAnswerThread,
 } from "@/lib/answer-thread-storage";
+import { useAnswerThreadBootstrap } from "@/components/clinical-dashboard/use-answer-thread-bootstrap";
+import {
+  resolveDashboardAnswerThreadOwnerId,
+  usePersistedAnswerThread,
+  type AnswerThreadSnapshotMetadata,
+} from "@/components/clinical-dashboard/use-persisted-answer-thread";
 import { buildAnswerClipboardText } from "@/components/clinical-dashboard/answer-copy-payload";
 import { buildAnswerRenderModel, isAnswerSourceBacked } from "@/lib/answer-render-policy";
 import {
@@ -342,6 +347,7 @@ export function ClinicalDashboard({
   const threadRestoreScrolledRef = useRef(false);
   const restoredThreadFromStorageRef = useRef(false);
   const latestAnswerTurnRef = useRef<Omit<AnswerTurn, "id"> | null>(null);
+  const latestAnswerSnapshotMetadataRef = useRef<AnswerThreadSnapshotMetadata | null>(null);
   const answerTurnSeqRef = useRef(0);
   const [documentMatches, setDocumentMatches] = useState<DocumentMatch[]>([]);
   const [searchRelevance, setSearchRelevance] = useState<EvidenceRelevance | null>(null);
@@ -401,6 +407,7 @@ export function ClinicalDashboard({
     setLatestAnswerQuery(null);
     setCollapsedTurnIds(new Set());
     setShowEarlierTurns(false);
+    latestAnswerSnapshotMetadataRef.current = null;
     const ownerId = activeAnswerThreadOwnerIdRef.current;
     if (ownerId) clearPersistedAnswerThread(ownerId);
   }, []);
@@ -656,57 +663,33 @@ export function ClinicalDashboard({
     openAccountProfile,
     setSettingsOpen: settingsState.setSettingsOpen,
   });
-  const answerThreadOwnerId = auth.session?.user.id ?? (clientDemoMode ? demoRecentQueryOwnerId : null);
-  const previousAnswerThreadOwnerIdRef = useRef(answerThreadOwnerId);
-  useEffect(() => {
-    const previousOwnerId = previousAnswerThreadOwnerIdRef.current;
-    previousAnswerThreadOwnerIdRef.current = answerThreadOwnerId;
-    activeAnswerThreadOwnerIdRef.current = answerThreadOwnerId;
-    if (!previousOwnerId || previousOwnerId === answerThreadOwnerId) return;
-    answerThreadBootstrappedRef.current = false;
-    queueMicrotask(() => {
-      setPriorAnswerTurns([]);
-      setLatestAnswerQuery(null);
-      setCollapsedTurnIds(new Set());
-      setAnswer(null);
-      setSources([]);
-      latestAnswerTurnRef.current = null;
-      setAnswerThreadBootstrapped(false);
-    });
-  }, [answerThreadOwnerId]);
-  useEffect(() => {
-    if (authStatus === "loading" || answerThreadBootstrappedRef.current) return;
-    queueMicrotask(() => {
-      const persisted = answerThreadOwnerId ? loadPersistedAnswerThread(answerThreadOwnerId) : null;
-      if (persisted) {
-        restoredThreadFromStorageRef.current = true;
-        setPriorAnswerTurns(persisted.priorTurns);
-        setLatestAnswerQuery(persisted.latestTurn?.query ?? null);
-        if (persisted.latestTurn) {
-          latestAnswerTurnRef.current = persisted.latestTurn;
-          setAnswer(persisted.latestTurn.answer);
-          setSources(persisted.latestTurn.sources);
-          setModeSearchSubmitted(true);
-          setQuery("");
-          const restoredQuery = persisted.latestTurn.query.trim();
-          if (restoredQuery) autoRunSearchSignatureRef.current = `answer:${restoredQuery}`;
-        }
-        answerTurnSeqRef.current = persisted.priorTurns.reduce((max, turn) => {
-          const match = /^answer-turn-(\d+)$/.exec(turn.id);
-          return match ? Math.max(max, Number(match[1])) : max;
-        }, 0);
-        setCollapsedTurnIds(
-          persisted.collapsedTurnIds.length
-            ? new Set(persisted.collapsedTurnIds)
-            : new Set(persisted.priorTurns.map((turn) => turn.id)),
-        );
-      } else if (!answerThreadOwnerId) {
-        clearPersistedAnswerThread();
-      }
-      answerThreadBootstrappedRef.current = true;
-      setAnswerThreadBootstrapped(true);
-    });
-  }, [answerThreadOwnerId, authStatus]);
+  const answerThreadOwnerId = resolveDashboardAnswerThreadOwnerId(auth.session?.user.id, clientDemoMode, authStatus);
+  useAnswerThreadBootstrap({
+    answerThreadOwnerId,
+    authStatus,
+    searchMode,
+    submittedUrlQuery,
+    expectedSubmissionSignature:
+      searchMode === "answer" && submittedUrlQuery
+        ? searchSubmissionSignature(searchMode, submittedUrlQuery, routedSearchContext)
+        : undefined,
+    activeAnswerThreadOwnerIdRef,
+    answerThreadBootstrappedRef,
+    restoredThreadFromStorageRef,
+    latestAnswerTurnRef,
+    latestAnswerSnapshotMetadataRef,
+    answerTurnSeqRef,
+    autoRunSearchSignatureRef,
+    setPriorAnswerTurns,
+    setLatestAnswerQuery,
+    setCollapsedTurnIds,
+    setShowEarlierTurns,
+    setAnswer,
+    setSources,
+    setModeSearchSubmitted,
+    setQuery,
+    setAnswerThreadBootstrapped,
+  });
   // Local no-auth can still exercise public-read APIs, but administration is always
   // derived separately from the immutable account role claim.
   const uploadReadOnlyMode = resolveUploadReadOnlyMode({
@@ -839,29 +822,16 @@ export function ClinicalDashboard({
     [answerThreadOwnerId],
   );
 
-  useEffect(() => {
-    if (!answerThreadBootstrapped) return;
-    if (searchMode !== "answer") return;
-    if (!answer && priorAnswerTurns.length === 0) {
-      if (answerThreadOwnerId) clearPersistedAnswerThread(answerThreadOwnerId);
-      return;
-    }
-    if (!answerThreadOwnerId) return;
-    savePersistedAnswerThread(answerThreadOwnerId, {
-      version: 1,
-      priorTurns: priorAnswerTurns,
-      latestTurn: latestAnswerTurnRef.current,
-      collapsedTurnIds: [...collapsedTurnIds],
-    });
-  }, [
-    searchMode,
+  usePersistedAnswerThread({
+    ownerId: answerThreadOwnerId,
+    enabled: answerThreadBootstrapped && searchMode === "answer",
     answer,
-    priorAnswerTurns,
+    priorTurns: priorAnswerTurns,
+    latestTurn: latestAnswerTurnRef.current,
     collapsedTurnIds,
-    latestAnswerQuery,
-    answerThreadBootstrapped,
-    answerThreadOwnerId,
-  ]);
+    showEarlierTurns,
+    metadata: latestAnswerSnapshotMetadataRef.current,
+  });
 
   useEffect(() => {
     documentsRef.current = documents;
@@ -1820,7 +1790,7 @@ export function ClinicalDashboard({
     const priorTurn = archivePreviousAnswer ? latestAnswerTurnRef.current : null;
     if (priorTurn) {
       const turnId = `answer-turn-${++answerTurnSeqRef.current}`;
-      setPriorAnswerTurns((turns) => [...turns, { id: turnId, ...priorTurn }].slice(-maxStoredAnswerTurns));
+      setPriorAnswerTurns((turns) => [...turns, { id: turnId, ...priorTurn }].slice(-(maxStoredAnswerTurns - 1)));
       setCollapsedTurnIds((current) => new Set(current).add(turnId));
     }
     const committedQuery = displayQuery ?? payload.query;
@@ -2100,6 +2070,15 @@ export function ClinicalDashboard({
 
       // M10: discard a stale response — a newer search owns the UI state.
       if (requestIsCurrent()) {
+        if (successfulPayload.kind === "answer") {
+          latestAnswerSnapshotMetadataRef.current = createAnswerThreadSnapshotMetadata(
+            searchSubmissionSignature(targetMode, trimmedQuery, {
+              queryMode: targetQueryMode,
+              scopeFilters: filtersOverride,
+              scopeRef: privateScopeRef,
+            }),
+          );
+        }
         applySearchResult(successfulPayload, trimmedQuery, !replaceExistingAnswer);
         if (isDifferentialsMode) setDifferentialEvidenceQuery(trimmedQuery);
         if (successfulPayload.kind === "answer") {
@@ -2108,11 +2087,8 @@ export function ClinicalDashboard({
           // effect. Seed their completed context so a later in-place route to
           // the same query with different intent/scope is recognized as a
           // replacement search instead of leaving the old answer on screen.
-          autoRunSearchSignatureRef.current = searchSubmissionSignature(targetMode, trimmedQuery, {
-            queryMode: targetQueryMode,
-            scopeFilters: filtersOverride,
-            scopeRef: privateScopeRef,
-          });
+          autoRunSearchSignatureRef.current =
+            latestAnswerSnapshotMetadataRef.current?.latestSubmissionSignature ?? null;
           // The composer is a draft box in a conversation: clear it so the
           // user can type the next follow-up immediately.
           setQuery("");

src/components/DocumentViewer.tsx

@@ -1,6 +1,5 @@
 "use client";
 
-import Link from "next/link";
 import { useRouter } from "next/navigation";
 import {
   CircleAlert,
@@ -17,6 +16,7 @@ import {
 } from "lucide-react";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { documentDisplayTitle } from "@/components/DocumentOrganizationBadges";
+import { ContextualBackLink } from "@/components/contextual-back-link";
 import { PhoneFooterLayerPortal } from "@/components/clinical-dashboard/phone-footer-layer-portal";
 import { useActiveScrollOwner } from "@/components/clinical-dashboard/use-active-scroll-owner";
 import { PhoneHeaderCollapsePortal } from "@/components/clinical-dashboard/phone-header-collapse-portal";
@@ -1091,14 +1091,14 @@ export function DocumentViewer({
           className="edge-glass-header relative z-30 border-b border-[color:var(--border)] py-2 shadow-[var(--shadow-tight)] backdrop-blur-xl max-sm:pt-2 sm:sticky sm:top-0 sm:pt-[max(0.5rem,env(safe-area-inset-top))]"
         >
           <div className="mx-auto flex min-h-12 min-w-0 max-w-[1440px] items-center gap-2">
-            <Link
-              href={documentHomeHref}
+            <ContextualBackLink
+              fallbackHref={documentHomeHref}
               className="inline-flex min-h-tap shrink-0 items-center gap-1.5 rounded-full pl-1.5 pr-3 text-sm font-semibold text-[color:var(--text-muted)] transition hover:bg-[color:var(--surface-subtle)] hover:text-[color:var(--text)]"
               aria-label="Back to documents"
             >
               <ArrowLeft aria-hidden="true" className="h-5 w-5 shrink-0" />
               <span className="hidden sm:inline">Documents</span>
-            </Link>
+            </ContextualBackLink>
             {documentSections.length > 0 ? (
               // The title is the section-list disclosure. Line two names where you
               // are, which the track can place but never label.