fix(landing/QueryLanding): restore the live cache demo with a real 'useQuery' hero

src/components/landing/LibraryLanding.tsx

@@ -66,6 +66,7 @@ export type LibraryLandingConfig = {
     items: readonly LibraryLandingWorkbenchItem[]
     label: string
   }
+  heroRender?: React.ReactNode
   libraryId: LibraryLandingId
   lifecycle: {
     body: string
@@ -189,7 +190,7 @@ export function LibraryLanding({ config }: { config: LibraryLandingConfig }) {
     <LibraryLandingShell
       description={config.description}
       headline={config.headline}
-      hero={<LandingWorkbench config={config.hero} />}
+      hero={config.heroRender ?? <LandingWorkbench config={config.hero} />}
       libraryId={config.libraryId}
       prompt={config.prompt}
       promptLabel={config.promptLabel}

src/components/landing/QueryLanding.tsx

@@ -1,12 +1,67 @@
+import * as React from 'react'
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import {
+  ArrowsClockwiseIcon,
   EyeClosedIcon,
   KeyIcon,
   LightningIcon,
+  PlusIcon,
   SkullIcon,
 } from '@phosphor-icons/react'
 
+import { usePrefersReducedMotion } from '~/utils/usePrefersReducedMotion'
 import { LibraryLanding, type LibraryLandingConfig } from './LibraryLanding'
 
+type QueryHeroIssue = {
+  id: string
+  observers: number
+  priority: number
+  title: string
+}
+
+type QueryHeroSnapshot = {
+  fetchedAt: number
+  revision: number
+  rows: Array<QueryHeroIssue>
+}
+
+type QueryHeroMutationContext = {
+  previous?: QueryHeroSnapshot
+}
+
+const queryHeroKey = ['landing-query-hero'] as const
+
+const queryHeroInitialRows: Array<QueryHeroIssue> = [
+  { id: 'router-cache', observers: 3, priority: 98, title: 'Router dashboard' },
+  { id: 'project-detail', observers: 2, priority: 91, title: 'Project detail' },
+  {
+    id: 'offline-queue',
+    observers: 1,
+    priority: 84,
+    title: 'Offline mutation queue',
+  },
+]
+
+const queryHeroInitialSnapshot: QueryHeroSnapshot = {
+  // `0` keeps `Date.now()` out of the first render so SSR and hydration agree.
+  fetchedAt: 0,
+  revision: 0,
+  rows: queryHeroInitialRows,
+}
+
+const queryHeroMutationTitles = [
+  'Optimistic table edit',
+  'Search filter sync',
+  'Background retry lane',
+  'Prefetched route data',
+]
+
+function waitForQueryHero(ms: number) {
+  return new Promise<void>((resolve) => {
+    setTimeout(resolve, ms)
+  })
+}
+
 const queryLanding = {
   libraryId: 'query',
   headline: 'The server-state standard for modern frontend apps.',
@@ -115,5 +170,275 @@ const queryLanding = {
 } satisfies LibraryLandingConfig
 
 export default function QueryLanding() {
-  return <LibraryLanding config={queryLanding} />
+  return (
+    <LibraryLanding
+      config={{ ...queryLanding, heroRender: <QueryCachePanel /> }}
+    />
+  )
+}
+
+function QueryCachePanel() {
+  const prefersReducedMotion = usePrefersReducedMotion()
+  const queryClient = useQueryClient()
+  const serverRowsRef = React.useRef(queryHeroInitialRows)
+  const serverRevisionRef = React.useRef(0)
+  const mutationSequenceRef = React.useRef(0)
+  // Starts paused so the server render matches the first client render; the
+  // effect below turns it on unless the visitor asked for reduced motion.
+  const [isLive, setIsLive] = React.useState(false)
+  // `0` until the first tick, for the same first-render reason as `fetchedAt`.
+  const [now, setNow] = React.useState(0)
+  const [selectedId, setSelectedId] = React.useState(
+    queryHeroInitialRows[0]?.id,
+  )
+
+  const projectsQuery = useQuery({
+    queryKey: queryHeroKey,
+    queryFn: async (): Promise<QueryHeroSnapshot> => {
+      await waitForQueryHero(620)
+
+      return {
+        fetchedAt: Date.now(),
+        revision: serverRevisionRef.current,
+        rows: serverRowsRef.current,
+      }
+    },
+    initialData: queryHeroInitialSnapshot,
+    initialDataUpdatedAt: 0,
+    refetchInterval: isLive ? 4200 : false,
+    staleTime: 3200,
+  })
+
+  const addIssueMutation = useMutation<
+    QueryHeroIssue,
+    Error,
+    QueryHeroIssue,
+    QueryHeroMutationContext
+  >({
+    mutationFn: async (issue) => {
+      await waitForQueryHero(720)
+      serverRevisionRef.current += 1
+      serverRowsRef.current = [
+        issue,
+        ...serverRowsRef.current.filter((row) => row.id !== issue.id),
+      ].slice(0, 5)
+
+      return issue
+    },
+    onMutate: async (issue) => {
+      await queryClient.cancelQueries({ queryKey: queryHeroKey })
+      const previous = queryClient.getQueryData<QueryHeroSnapshot>(queryHeroKey)
+
+      queryClient.setQueryData<QueryHeroSnapshot>(queryHeroKey, (current) => ({
+        fetchedAt: current?.fetchedAt ?? 0,
+        revision: current?.revision ?? serverRevisionRef.current,
+        rows: [
+          issue,
+          ...(current?.rows ?? queryHeroInitialRows).filter(
+            (row) => row.id !== issue.id,
+          ),
+        ].slice(0, 5),
+      }))
+
+      return { previous }
+    },
+    onError: (_error, _issue, context) => {
+      if (context?.previous) {
+        queryClient.setQueryData<QueryHeroSnapshot>(
+          queryHeroKey,
+          context.previous,
+        )
+      }
+    },
+    onSettled: () => queryClient.invalidateQueries({ queryKey: queryHeroKey }),
+  })
+
+  const cacheState = projectsQuery.isFetching
+    ? 'fetching'
+    : projectsQuery.isStale
+      ? 'stale'
+      : 'fresh'
+  // The selected row can fall out of the cache once five newer issues arrive,
+  // so fall back to the top row rather than holding a dangling id.
+  const selectedRow =
+    projectsQuery.data.rows.find((row) => row.id === selectedId) ??
+    projectsQuery.data.rows[0]
+  const fetchedLabel =
+    projectsQuery.data.fetchedAt > 0
+      ? `${Math.max(0, Math.round((Math.max(now, projectsQuery.data.fetchedAt) - projectsQuery.data.fetchedAt) / 1000))}s ago`
+      : 'primed'
+
+  React.useEffect(() => {
+    if (prefersReducedMotion === null) return
+
+    setIsLive(prefersReducedMotion === false)
+  }, [prefersReducedMotion])
+
+  React.useEffect(() => {
+    const id = setInterval(() => setNow(Date.now()), 1000)
+    return () => clearInterval(id)
+  }, [])
+
+  const addIssue = () => {
+    const nextSequence = mutationSequenceRef.current + 1
+    const nextTitle =
+      queryHeroMutationTitles[
+        (nextSequence - 1) % queryHeroMutationTitles.length
+      ]
+
+    mutationSequenceRef.current = nextSequence
+    addIssueMutation.mutate({
+      id: `optimistic-${nextSequence}`,
+      observers: (nextSequence % 3) + 1,
+      priority: 72 + ((nextSequence * 7) % 24),
+      title: nextTitle ?? 'Optimistic write',
+    })
+  }
+
+  return (
+    <div className="library-landing-graphic min-w-0 overflow-hidden rounded-xl border border-[color:rgb(var(--landing-glow)/0.45)] bg-background-surface shadow-[0_24px_70px_-28px_rgb(var(--landing-glow)/0.45)] dark:shadow-[inset_-3px_-4px_18px_-7px_var(--landing-accent),0_24px_70px_rgb(0_0_0/0.18)]">
+      <div className="flex items-center justify-between border-b border-border-subtle px-4 py-3">
+        <div aria-hidden="true" className="flex gap-1.5">
+          <span className="size-2.5 rounded-full bg-[#ff5f57]" />
+          <span className="size-2.5 rounded-full bg-[#febc2e]" />
+          <span className="size-2.5 rounded-full bg-[#28c840]" />
+        </div>
+        <span className="font-ds-mono text-ds-mono-caps-xs uppercase text-text-primary/65">
+          {queryLanding.hero.label}
+        </span>
+      </div>
+
+      <div className="grid min-h-[22rem] lg:grid-cols-[1.08fr_0.82fr]">
+        <div className="space-y-3 border-border-subtle p-4 lg:border-r">
+          <div className="mb-4 flex flex-wrap items-center gap-2 font-ds-mono text-ds-mono-caps-xs uppercase">
+            <span
+              className={
+                cacheState === 'fresh'
+                  ? 'rounded-sm bg-emerald-500 px-2 py-1 text-emerald-950'
+                  : cacheState === 'fetching'
+                    ? 'rounded-sm bg-amber-400 px-2 py-1 text-amber-950'
+                    : 'rounded-sm bg-[var(--landing-accent)] px-2 py-1 text-[var(--landing-accent-ink)]'
+              }
+            >
+              {cacheState}
+            </span>
+            <span className="rounded-sm bg-text-primary/5 px-2 py-1 text-text-primary/35">
+              rev {projectsQuery.data.revision} / {fetchedLabel}
+            </span>
+          </div>
+
+          {projectsQuery.data.rows.map((row) => (
+            <button
+              key={row.id}
+              type="button"
+              aria-pressed={row.id === selectedRow?.id}
+              className="block w-full rounded-lg border border-transparent bg-background-subtle p-4 text-left transition-colors hover:border-text-primary/10 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--landing-accent-bright)] aria-pressed:border-[color:rgb(var(--landing-glow)/0.42)] aria-pressed:bg-[color:rgb(var(--landing-glow)/0.1)]"
+              onClick={() => setSelectedId(row.id)}
+            >
+              <span className="flex items-start justify-between gap-4">
+                <span className="min-w-0">
+                  <span className="block truncate font-ds-mono text-ds-mono-xs text-text-primary">
+                    ['issues', '{row.id}']
+                  </span>
+                  <span className="mt-1 block text-ds-body-xs text-text-primary/45">
+                    {row.title}
+                  </span>
+                </span>
+                <span className="shrink-0 rounded bg-[var(--landing-accent)] px-2 py-1 font-ds-mono text-ds-mono-2xs text-[var(--landing-accent-ink)]">
+                  P{row.priority}
+                </span>
+              </span>
+              <span className="mt-4 flex items-center gap-3">
+                <span className="h-1 flex-1 overflow-hidden rounded-full bg-text-primary/5">
+                  <span
+                    className="block h-full rounded-full bg-[var(--landing-accent)] transition-[width] duration-500 motion-reduce:transition-none"
+                    style={{ width: `${row.priority}%` }}
+                  />
+                </span>
+                <span className="font-ds-mono text-ds-mono-caps-xs uppercase text-text-primary/35">
+                  {row.observers}{' '}
+                  {row.observers === 1 ? 'observer' : 'observers'}
+                </span>
+              </span>
+            </button>
+          ))}
+        </div>
+
+        <div className="flex flex-col p-5">
+          <div className="flex flex-wrap items-center justify-between gap-2">
+            <button
+              type="button"
+              aria-pressed={isLive}
+              className="rounded-md bg-[#ff5f5f] px-3 py-2 text-ds-label-sm text-white transition-opacity hover:opacity-90 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-white"
+              onClick={() => setIsLive((current) => !current)}
+            >
+              Live {isLive ? 'on' : 'off'}
+            </button>
+            <div className="flex flex-wrap items-center gap-2">
+              <button
+                type="button"
+                className="inline-flex items-center gap-1.5 rounded-md border border-border-subtle px-3 py-2 text-ds-label-sm text-text-primary/70 transition-colors hover:text-text-primary focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--landing-accent-bright)]"
+                onClick={() => projectsQuery.refetch()}
+              >
+                <ArrowsClockwiseIcon
+                  aria-hidden="true"
+                  size={13}
+                  weight="bold"
+                  className={
+                    projectsQuery.isFetching
+                      ? 'animate-spin motion-reduce:animate-none'
+                      : ''
+                  }
+                />
+                Refetch
+              </button>
+              <button
+                type="button"
+                disabled={addIssueMutation.isPending}
+                className="inline-flex items-center gap-1.5 rounded-md bg-[#ff5f5f] px-3 py-2 text-ds-label-sm text-white transition-opacity hover:opacity-90 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-white disabled:cursor-wait disabled:opacity-70"
+                onClick={addIssue}
+              >
+                <PlusIcon aria-hidden="true" size={13} weight="bold" />
+                {queryLanding.hero.actionLabel}
+              </button>
+            </div>
+          </div>
+
+          <div className="mt-7" aria-live="polite">
+            <p className="text-ds-heading-4">{queryLanding.hero.detailTitle}</p>
+            <p className="mt-2 truncate font-ds-mono text-ds-mono-xs text-[var(--landing-accent-bright)]">
+              ['issues', '{selectedRow?.id ?? 'router-cache'}']
+            </p>
+            <p className="mt-4 text-ds-body-sm text-text-primary/55">
+              {queryLanding.hero.detailBody}
+            </p>
+          </div>
+
+          <dl className="mt-auto space-y-2 rounded-lg bg-background-subtle p-4 text-ds-body-xs">
+            {[
+              { label: 'status', value: projectsQuery.status },
+              {
+                label: 'isFetching',
+                value: String(projectsQuery.isFetching),
+              },
+              {
+                label: 'observers',
+                value: String(selectedRow?.observers ?? 0),
+              },
+              { label: 'priority', value: `P${selectedRow?.priority ?? 0}` },
+              { label: 'staleTime', value: '3,200' },
+              { label: 'mutation', value: addIssueMutation.status },
+            ].map((fact) => (
+              <div key={fact.label} className="flex justify-between gap-3">
+                <dt className="text-text-primary/45">{fact.label}</dt>
+                <dd className="text-right font-ds-mono text-ds-mono-xs text-text-primary/85">
+                  {fact.value}
+                </dd>
+              </div>
+            ))}
+          </dl>
+        </div>
+      </div>
+    </div>
+  )
 }