fix(web,api): tolerate null journey slices

internal/api/journey/nudge.go

@@ -54,14 +54,15 @@ func NudgeVerdict(now time.Time, recommended *time.Time, blockers []Item) string
 	return NudgeLeaveNow
 }
 
-// Blockers filters a run to action-level items. Nil run yields nil —
-// no run is not a blocker, it is flagged separately in evidence so a
+// Blockers filters a run to action-level items. Nil run yields an
+// empty slice (JSON []), not nil — the UI reads blockers.length.
+// No run is not a blocker; it is flagged separately in evidence so a
 // fresh trip does not read as broken. Pure.
 func Blockers(run *Run) []Item {
+	out := []Item{}
 	if run == nil {
-		return nil
+		return out
 	}
-	out := []Item{}
 	for _, item := range run.Items {
 		if item.Status == ItemAction {
 			out = append(out, item)

internal/api/journey/nudge_test.go

@@ -40,8 +40,8 @@ func TestNudgeVerdict(t *testing.T) {
 }
 
 func TestBlockers(t *testing.T) {
-	if b := Blockers(nil); b != nil {
-		t.Fatalf("nil = %+v, want nil", b)
+	if b := Blockers(nil); b == nil || len(b) != 0 {
+		t.Fatalf("nil run = %+v, want empty slice", b)
 	}
 	run := &Run{Items: []Item{
 		{Key: "a", Status: ItemOK},

web/src/api/hooks/useJourney.ts

@@ -276,6 +276,11 @@ export function useJourney(id: number | null | undefined, options?: { enabled?:
       request<JourneyDetail>(`/journey/sessions/${id}`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('operational'),
+    select: (data) => ({
+      ...data,
+      plans: safeArray(data?.plans),
+      next_statuses: safeArray(data?.next_statuses),
+    }),
   });
 }
 
@@ -339,6 +344,11 @@ export function useDeparture(
       ),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('operational'),
+    select: (data) => ({
+      ...data,
+      slots: safeArray(data?.slots),
+      evidence: safeArray(data?.evidence),
+    }),
   });
 }
 
@@ -350,6 +360,7 @@ export function useChecklist(id: number | null | undefined, options?: { enabled?
       request<ChecklistRun>(`/journey/sessions/${id}/checklist`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('operational'),
+    select: (data) => ({ ...data, items: safeArray(data?.items) }),
   });
 }
 
@@ -384,6 +395,11 @@ export function useJourneyLive(id: number | null | undefined, options?: { enable
       request<JourneyLiveView>(`/journey/sessions/${id}/live`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('live'),
+    select: (data) => ({
+      ...data,
+      trail: safeArray(data?.trail),
+      evidence: safeArray(data?.evidence),
+    }),
   });
 }
 
@@ -426,6 +442,7 @@ export function useReplanAssessment(id: number | null | undefined, options?: { e
       request<JourneyReplanAssessment>(`/journey/sessions/${id}/replan`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('operational'),
+    select: (data) => ({ ...data, evidence: safeArray(data?.evidence) }),
   });
 }
 
@@ -460,6 +477,7 @@ export function useArrival(id: number | null | undefined, options?: { enabled?:
       request<JourneyArrival>(`/journey/sessions/${id}/arrival`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('live'),
+    select: (data) => ({ ...data, evidence: safeArray(data?.evidence) }),
   });
 }
 
@@ -471,6 +489,7 @@ export function useReport(id: number | null | undefined, options?: { enabled?: b
       request<JourneyReport>(`/journey/sessions/${id}/report`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('operational'),
+    select: (data) => ({ ...data, evidence: safeArray(data?.evidence) }),
   });
 }
 
@@ -482,6 +501,11 @@ export function useNudge(id: number | null | undefined, options?: { enabled?: bo
       request<JourneyNudge>(`/journey/sessions/${id}/nudge`, { signal }),
     enabled: (options?.enabled ?? true) && id != null && id > 0,
     ...queryPolicy('operational'),
+    select: (data) => ({
+      ...data,
+      blockers: safeArray(data?.blockers),
+      evidence: safeArray(data?.evidence),
+    }),
   });
 }
 

web/src/api/hooks/useSystemDiagnostic.ts

@@ -10,7 +10,7 @@
 // losing the most recent run. On error we emit a toast so the failure
 // is visible even if the page is unmounted before the catch resolves.
 
-import { useMutation, useQueryClient } from '@tanstack/react-query';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
 import { request } from '../client';
 import { useMutationToast } from './_toastHelpers';
 import type { DiagnosticReport } from '../types';
@@ -53,10 +53,24 @@ export function useRunDiagnostic(options: UseRunDiagnosticOptions = {}) {
  * Convenience hook to read the most recent report without re-running
  * the diagnostic. Returns `undefined` until the user fires at least
  * one successful run in this session.
+ *
+ * Must subscribe via useQuery — getQueryData() is a one-shot read and
+ * does not notify React when onSuccess writes diagnosticKeys.last.
+ * Tests also use gcTime: 0, so an unobserved cache entry can be GC'd
+ * before the next render (CI flake: last stays undefined).
  */
 export function useLastDiagnostic(): DiagnosticReport | undefined {
-  const qc = useQueryClient();
-  return qc.getQueryData<DiagnosticReport>(diagnosticKeys.last);
+  const { data } = useQuery<DiagnosticReport>({
+    queryKey: diagnosticKeys.last,
+    queryFn: ({ signal }) => {
+      void signal;
+      throw new Error('diagnosticKeys.last is cache-only');
+    },
+    enabled: false,
+    staleTime: Infinity,
+    retry: false,
+  });
+  return data;
 }
 
 /**

web/src/features/settings/components/SettingsSearch.tsx

@@ -33,6 +33,7 @@ export function SettingsSearch({ className }: SettingsSearchProps) {
   const [open, setOpen] = useState(false);
   const [activeIndex, setActiveIndex] = useState(0);
   const wrapperRef = useRef<HTMLDivElement | null>(null);
+  const scrollTimerRef = useRef<ReturnType<typeof window.setTimeout> | null>(null);
   const listboxId = useId();
 
   const index = useMemo(() => getSettingsIndex(t), [t]);
@@ -61,6 +62,14 @@ export function SettingsSearch({ className }: SettingsSearchProps) {
     return () => document.removeEventListener('mousedown', handlePointerDown);
   }, [open]);
 
+  useEffect(() => {
+    return () => {
+      if (scrollTimerRef.current !== null) {
+        window.clearTimeout(scrollTimerRef.current);
+      }
+    };
+  }, []);
+
   function commit(entry: SettingsEntry) {
     setQuery('');
     setOpen(false);
@@ -72,7 +81,12 @@ export function SettingsSearch({ className }: SettingsSearchProps) {
     // resolver and our smooth-scroll behave consistently.
     const id = entry.href.split('#')[1];
     if (!id) return;
-    window.setTimeout(() => {
+    if (scrollTimerRef.current !== null) {
+      window.clearTimeout(scrollTimerRef.current);
+    }
+    scrollTimerRef.current = window.setTimeout(() => {
+      scrollTimerRef.current = null;
+      if (typeof document === 'undefined') return;
       const el = document.getElementById(id);
       if (el) el.scrollIntoView({ behavior: 'smooth', block: 'start' });
     }, SCROLL_FALLBACK_DELAY_MS);

web/src/features/settings/components/__tests__/SettingsSearch.test.tsx

@@ -192,4 +192,27 @@ describe('SettingsSearch', () => {
     // the user-visible promise we care about.
     expect(screen.getByTestId('location').textContent).toBe('/settings#appearance');
   });
+
+  it('clears the hash-scroll fallback timer on unmount', () => {
+    vi.useFakeTimers();
+    try {
+      const { unmount } = renderSearch();
+      const input = screen.getByPlaceholderText('Search settings…');
+
+      act(() => {
+        fireEvent.focus(input);
+        fireEvent.change(input, { target: { value: 'theme' } });
+        fireEvent.keyDown(input, { key: 'Enter' });
+      });
+
+      unmount();
+      expect(() => {
+        act(() => {
+          vi.runAllTimers();
+        });
+      }).not.toThrow();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
 });

web/src/features/trips/components/ArrivalPanel.tsx

@@ -7,6 +7,7 @@ import { Badge, Text } from '@/components/ui';
 import { ListSkeleton, QueryError } from '@/components/feedback';
 import { formatTime } from '@/lib/dateFormat';
 import { fmtNumber } from '@/lib/numberFormat';
+import { safeArray } from '@/lib/safeArray';
 
 const VERDICT_LABEL_KEYS: Record<ChecklistStatus, string> = {
   ok: 'journey.arrival.verdict.ok',
@@ -47,6 +48,7 @@ export function ArrivalPanel({ session }: { session: JourneySession }) {
   const arrivalQuery = useArrival(session.id);
   const arrivalState = useDataState(arrivalQuery);
   const arrival = arrivalQuery.data ?? null;
+  const arrivalEvidence = safeArray(arrival?.evidence);
 
   return (
     <div className="space-y-4">
@@ -107,9 +109,9 @@ export function ArrivalPanel({ session }: { session: JourneySession }) {
             ) : null}
           </div>
 
-          {arrival.evidence.length > 0 ? (
+          {arrivalEvidence.length > 0 ? (
             <ul className="space-y-1">
-              {arrival.evidence.map((line) => (
+              {arrivalEvidence.map((line) => (
                 <Text as="li" key={line} size="xs" color="muted">
                   · {line}
                 </Text>

web/src/features/trips/components/ChecklistPanel.tsx

@@ -11,6 +11,7 @@ import { Badge, Button, Text } from '@/components/ui';
 import { EmptyState, ListSkeleton, QueryError } from '@/components/feedback';
 import { isApiError } from '@/lib/resilience';
 import { formatDateTime } from '@/lib/dateFormat';
+import { safeArray } from '@/lib/safeArray';
 
 const ITEM_LABEL_KEYS = {
   charge_level: 'journey.checklist.item.charge_level',
@@ -67,6 +68,7 @@ export function ChecklistPanel({ session }: { session: JourneySession }) {
   const runQuery = useChecklist(session.id);
   const runState = useDataState(runQuery);
   const run = runQuery.data ?? null;
+  const items = safeArray(run?.items);
 
   const refresh = useRefreshChecklist();
 
@@ -130,7 +132,7 @@ export function ChecklistPanel({ session }: { session: JourneySession }) {
             })}
           </Text>
           <ul className="space-y-2">
-            {run.items.map((item) => (
+            {items.map((item) => (
               <li
                 key={item.key}
                 className="flex items-start justify-between gap-3 rounded-lg border border-white/[0.07] bg-white/[0.02] px-3 py-2"

web/src/features/trips/components/DeparturePanel.tsx

@@ -7,6 +7,7 @@ import { Badge, Button, Text } from '@/components/ui';
 import { ListSkeleton, QueryError } from '@/components/feedback';
 import { formatTime } from '@/lib/dateFormat';
 import { fmtNumber } from '@/lib/numberFormat';
+import { safeArray } from '@/lib/safeArray';
 
 const HORIZONS = [12, 24, 48] as const;
 
@@ -42,6 +43,7 @@ export function DeparturePanel({ session }: { session: JourneySession }) {
   });
   const adviceState = useDataState(adviceQuery);
   const advice = adviceQuery.data ?? null;
+  const slots = safeArray(advice?.slots);
 
   if (!hasOrigin) {
     return (
@@ -79,7 +81,7 @@ export function DeparturePanel({ session }: { session: JourneySession }) {
         <ListSkeleton label={t('journey.departure.loading', 'Scoring departure hours…')} />
       ) : adviceState.fatalError ? (
         <QueryError error={adviceState.fatalError} onRetry={() => adviceState.retry?.()} />
-      ) : advice == null || advice.slots.length === 0 ? (
+      ) : advice == null || slots.length === 0 ? (
         <Text as="p" size="sm" color="secondary">
           {t('journey.departure.uncovered', 'The forecast covers none of this window.')}
         </Text>
@@ -106,7 +108,7 @@ export function DeparturePanel({ session }: { session: JourneySession }) {
             </Badge>
           )}
           <div className="flex flex-wrap gap-1.5" role="list" aria-label={t('journey.departure.slots', 'Departure hours')}>
-            {advice.slots.map((slot) => (
+            {slots.map((slot) => (
               <span
                 key={slot.depart_at}
                 role="listitem"
@@ -122,7 +124,7 @@ export function DeparturePanel({ session }: { session: JourneySession }) {
             ))}
           </div>
           <ul className="space-y-1">
-            {advice.evidence.map((line) => (
+            {safeArray(advice.evidence).map((line) => (
               <Text as="li" key={line} size="xs" color="muted">
                 · {line}
               </Text>

web/src/features/trips/components/JourneyPanel.test.tsx

@@ -233,4 +233,44 @@ describe('JourneyPanel', () => {
     fireEvent.click(screen.getByText('Retry'));
     expect(refetch).toHaveBeenCalled();
   });
+
+  it('renders when Go sends null slices on a planned journey', () => {
+    mockDetail.mockReturnValue(
+      idle({
+        data: { session: sessions[0], plans: null, next_statuses: null },
+      }),
+    );
+    mockNudge.mockReturnValue(
+      idle({
+        data: {
+          session_id: 1,
+          verdict: 'unknown',
+          slot_at: null,
+          blockers: null,
+          evidence: null,
+        },
+      }),
+    );
+    mockChecklist.mockReturnValue(
+      idle({
+        data: {
+          id: 1,
+          session_id: 1,
+          run_at: '2026-09-10T10:00:00Z',
+          items: null,
+        },
+      }),
+    );
+    mockList.mockReturnValue(idle({ data: null }));
+    const { unmount } = renderPanel();
+    expect(screen.getByText(/No journeys yet/)).toBeInTheDocument();
+    unmount();
+
+    mockList.mockReturnValue(idle({ data: sessions }));
+    renderPanel();
+    fireEvent.click(screen.getAllByText('Open')[0]);
+    expect(screen.getAllByText('Tahoe ski trip').length).toBeGreaterThan(0);
+    expect(screen.getByText(/No plans saved yet/)).toBeInTheDocument();
+    expect(screen.getByText('Leave now?')).toBeInTheDocument();
+  });
 });

web/src/features/trips/components/JourneyPanel.tsx

@@ -15,6 +15,7 @@ import { Badge, Button, DataTable, GlassPanel, Input, PanelTitle, Select, Text }
 import type { Column } from '@/components/ui';
 import { EmptyState, ListSkeleton, QueryError } from '@/components/feedback';
 import { formatDateTime } from '@/lib/dateFormat';
+import { safeArray } from '@/lib/safeArray';
 import { StopScorePanel } from './StopScorePanel';
 import { DeparturePanel } from './DeparturePanel';
 import { ChecklistPanel } from './ChecklistPanel';
@@ -109,7 +110,7 @@ export function JourneyPanel({ vehicleId }: { vehicleId: number | null }) {
 
   const listQuery = useJourneys(vehicleId, statusFilter);
   const listState = useDataState(listQuery);
-  const sessions = listQuery.data ?? [];
+  const sessions = safeArray(listQuery.data);
 
   const detailQuery = useJourney(selectedId);
   const detailState = useDataState(detailQuery);
@@ -321,7 +322,7 @@ export function JourneyPanel({ vehicleId }: { vehicleId: number | null }) {
               <Badge variant={statusVariant(detail.session.status)}>
                 {statusLabel(detail.session.status)}
               </Badge>
-              {detail.next_statuses.map((next) => {
+              {safeArray(detail.next_statuses).map((next) => {
                 const action = transitionAction(next, detail.session.status);
                 return (
                   <Button
@@ -342,13 +343,13 @@ export function JourneyPanel({ vehicleId }: { vehicleId: number | null }) {
                 <Icons.package className="h-4 w-4" aria-hidden="true" />
                 {t('journey.plans.title', 'Plan versions')}
               </Text>
-              {detail.plans.length === 0 ? (
+              {safeArray(detail.plans).length === 0 ? (
                 <Text as="p" size="sm" color="secondary">
                   {t('journey.plans.empty', 'No plans saved yet — the stop optimizer lands here.')}
                 </Text>
               ) : (
                 <ul className="space-y-2">
-                  {detail.plans.map((plan) => (
+                  {safeArray(detail.plans).map((plan) => (
                     <li
                       key={plan.id}
                       className="flex items-center justify-between gap-3 rounded-lg border border-white/[0.07] bg-white/[0.02] px-3 py-2"