feat(PBI-74): Zustand product-workspace rearchitecture (Stories 1-8) (#180)

* feat(PBI-74): product-workspace store skelet + test-infra (Story 1)

Skelet voor de nieuwe `product-workspace-store` die op termijn de gefragmenteerde
`backlog-store`/`planner-store`/`selection-store`/`product-store` vervangt. Deze
PR levert alleen het skelet + tests; UI-consumers worden in latere stories
omgezet.

- vitest naar jsdom + tests/setup.ts (MemoryStorage, default fetch-stub) — G6/G8
- stores/product-workspace/{types,store,selectors,restore}.ts — immer-middleware,
  alle slices en acties (hydrate, setActive*, ensure*Loaded met activeRequestId-
  guard, applyRealtimeEvent, resyncActiveScopes/loadedScopes, optimistic
  mutations). Restore-wiring in setters volgt in Story 4 (T-857/T-858).
- selectors gebruiken module-level EMPTY refs (G1) en documenteren useShallow-
  vereiste (G2)
- 34 nieuwe unit-tests dekken §Testing setup-checklist uit het ontwerp:
  hydrateSnapshot, selection-cascade, applyRealtimeEvent (I/U/D + parent-move +
  ander-product + unknown-entity → resync), delete-cleanup, race-safe loaders,
  ensureTaskLoaded _detail-flag, resyncActiveScopes ensure-keten, restore-hints
  read/write/clear, optimistic mutation rollback/settle/SSE-echo idempotent
- docs/api/rest-contract.md: audit-sectie met de vier ontbrekende
  ensure*Loaded-endpoints (worden toegevoegd in Story 7 / T-870)

Refs: PBI-74, ST-1318, T-837..T-843
Bron-ontwerp: docs/plans/zustand-store-rearchitecture.md
Implementatieplan: docs/plans/zustand-workspace-store-implementation.md

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): dual-dispatch hydratie + realtime naar workspace-store (Story 2)

Story 2 — schaduw-fase: BacklogHydrationWrapper en useBacklogRealtime voeden
nu ook de nieuwe product-workspace-store, terwijl de oude useBacklogStore /
useProductStore leidend blijft voor componenten. Story 3 verschuift consumers
één voor één; Story 8 ruimt de oude stores op.

- T-844: BacklogHydrationWrapper roept naast useBacklogStore.setInitialData
  ook useProductWorkspaceStore.hydrateSnapshot aan. Productname-prop optioneel
  toegevoegd voor activeProduct-context.
- T-845: useBacklogRealtime onmessage dispatcht events naar zowel oude store
  (applyChange) als nieuwe store (applyRealtimeEvent). Geen wijziging aan
  reconnect/visibility — Story 5.
- T-846: dev-only logWorkspaceFingerprint helper vergelijkt counts tussen
  oude en nieuwe store na hydrate en na elk realtime-event. console.warn bij
  mismatch; opt-in debug log via NEXT_PUBLIC_DEBUG_WORKSPACE_FINGERPRINT=1.
  Bestand TODO-marked voor verwijdering in Story 8 (T-878).
- T-847: SetCurrentProduct schrijft naast oude useProductStore ook
  useProductWorkspaceStore.setActiveProduct({id, name}); cleanup cleart beide.
  setActiveProduct triggert ensureProductLoaded — fetch-stub tot Story 7
  (T-870) de LIST-endpoints toevoegt.

Verify: lint+typecheck clean, 636/636 tests groen (geen UI-regressie omdat
oude store leidend blijft).

Refs: PBI-74, ST-1319, T-844..T-847

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): migreer backlog-componenten naar workspace-store (Story 3)

Story 3 verplaatst alle UI-consumers van de oude vier stores
(useBacklogStore/usePlannerStore/useSelectionStore/useProductStore) naar de
nieuwe product-workspace-store. De oude stores blijven nog bestaan voor
hydration-wrapper en realtime-hook (dual-dispatch); Story 8 ruimt ze op.

- T-848 backlog-split-pane.tsx: leest activePbiId/activeStoryId uit
  context-slice (primitives, geen useShallow nodig).
- T-849 pbi-list.tsx: selectVisiblePbis(useShallow); DnD via
  applyOptimisticMutation('pbi-order' + optionele 'entity-patch' bij
  cross-priority drag), met settle/rollback per server-result.
- T-850 story-panel.tsx: selectStoriesForActivePbi(useShallow); DnD via
  applyOptimisticMutation('story-order' + entity-patch bij priority change).
- T-851 task-panel.tsx: selectTasksForActiveStory(useShallow); DnD via
  applyOptimisticMutation('task-order'); detail-view (ensureTaskLoaded +
  isDetail) zit in de task-dialog (apart component, niet in deze lijst).
- T-852 start-sprint-button.tsx: selectActivePbi + selectStoriesForActivePbi
  voor free-story count.
- T-853 set-current-product.tsx: alleen workspace-store.setActiveProduct
  (oude useProductStore-import verwijderd).
- T-854 G1/G2-audit: alle nieuwe selectors gebruiken module-level EMPTY
  refs (G1) en useShallow voor lijsten (G2). Geen 'Maximum update depth'-
  warnings tijdens npm test.
- T-855 tests bijgewerkt: backlog-split-pane.test, task-panel.test,
  integration.test gebruiken nu setState op workspace-store (helpers
  resetWorkspace/setActiveStoryAndTasks/selectPbi/selectStory).

Verify: lint+typecheck clean, 636/636 tests groen. UI-consumers van
oude stores zijn nu nul (uitgezonderd dual-dispatch in hydration-wrapper en
realtime-hook + dev-fingerprint-helper, die in Story 8/T-873/T-878 verdwijnen).

Refs: PBI-74, ST-1320, T-848..T-855

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): race-safe loaders + restore-hints + URL-prioriteit (Story 4)

- T-856: activeRequestId-guard zat al in store.ts uit Story 1; bevestigd door
  de race-safety test (in-flight ensurePbiLoaded mag niet overschrijven).
- T-857: restore-hint flow toegevoegd in setActiveProduct/setActivePbi/
  setActiveStory. Async chain: await ensureXxxLoaded → guard check →
  readHints → valideer hint via entities.byId → setActiveYyy(hint).
  Geen setTimeout-trick — chain is alleen await-based.
- T-858: writeProductHint/writePbiHint/writeStoryHint/writeTaskHint
  aangeroepen direct na set(...) zodat de hint-persistentie altijd
  consistent is met de in-store selectie.
- T-859: nieuwe components/backlog/url-task-sync.tsx — leest
  ?editTask=&lt;id&gt; uit useSearchParams, schrijft de hint en roept
  setActiveTask aan zodat de URL wint boven een eerder gepersisteerde
  task-hint. Gemount in beide product-pages (desktop + mobile) binnen
  BacklogHydrationWrapper.
- T-860: 6 nieuwe vitest-cases — 4 voor hint-persist per setter, 2 voor de
  restore-flow chain (hint die niet in entities zit wordt genegeerd; hint
  die wel in entities zit wordt toegepast). Bestaande race-safety test
  blijft groen.

Verify: lint+typecheck clean, 642/642 tests groen.

Refs: PBI-74, ST-1321, T-856..T-860

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): hidden-tab + reconnect resync (Story 5)

Per ontwerp samen in één commit zodat geen vangnet wegvalt zonder vervanging.

- T-861: useBacklogRealtime sluit niet meer op visibilitychange hidden;
  EventSource blijft open zolang browser/netwerk dit toelaten. Reconnect bij
  netwerkfout blijft via backoff. visibilitychange fungeert nog wel als
  re-connect-trigger als de stream tussentijds is gesloten (b.v. 240s
  hard-close server-side).
- T-862: 'ready'-event-handler telt connect-cycles. De eerste 'ready' is de
  initial connect (geen resync). Bij latere 'ready' (post-reconnect) wordt
  resyncActiveScopes('reconnect') aangeroepen om gemiste events op te halen.
- T-863: nieuwe lib/realtime/use-workspace-resync.ts — luistert op
  document.visibilitychange (hidden→visible) en window.online; dispatcht
  resyncActiveScopes('visible') resp. 'reconnect'. Mounted in
  BacklogHydrationWrapper na useBacklogRealtime.
- T-864: 4 nieuwe vitest-cases voor useWorkspaceResync (jsdom): visible→
  visible event, online event, hidden negeren, cleanup-bij-unmount.

Daarnaast lint-cleanup: ongebruikte 'order'-variabelen in pbi-list en
story-panel weggehaald.

Verify: lint+typecheck clean, 646/646 tests groen.

Refs: PBI-74, ST-1322, T-861..T-864

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): unknown-event fallback tests (Story 6)

T-865 (isUnknownEntityEvent filter) en T-866 (resync-trigger in
applyRealtimeEvent) zijn al in Story 1 geïmplementeerd in store.ts;
deze story breidt de test-coverage uit met expliciete negatieve cases
voor het type-veld noise pattern.

T-867 — 5 nieuwe vitest-cases:
- unknown entity met ANDER product_id → geen resync
- claude_job_status (type) → geen resync
- worker_heartbeat (type) → geen resync
- claude_job_enqueued (type) → geen resync
- payload zonder entity en zonder type → genegeerd
- question-entity (entity-veld, geen type, niet pbi/story/task) → resync trigger

Verify: lint+typecheck clean, 651/651 tests groen.

Refs: PBI-74, ST-1323, T-865..T-867

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): cache-headers + LIST endpoints (Story 7)

- T-868: cache: 'no-store' was al ingebouwd in fetchJson helper (Story 1).
  Bevestigd door bestaande ensureProductLoaded test die de fetch-init
  controleert.
- T-869: force-dynamic toegevoegd op alle vier nieuwe LIST-endpoints.
- T-870: vier nieuwe routes voor ensure*Loaded:
  - GET /api/products/:id/backlog → ProductBacklogSnapshot
  - GET /api/pbis/:id/stories → BacklogStory[]
  - GET /api/stories/:id/tasks → BacklogTask[]
  - GET /api/tasks/:id (nieuwe handler naast bestaande PATCH) → TaskDetail
    met _detail: true marker
  Auth via authenticateApiRequest (Bearer of iron-session); access-control
  via productAccessFilter (gebruiker is owner of member van het product).
  Statussen worden via taskStatusToApi/storyStatusToApi/pbiStatusToApi
  vertaald naar lowercase API-vorm.
- T-871: SSE-route /api/realtime/backlog stuurt al ready-event direct na
  LISTEN (regel 106) — geen wijziging nodig.

Verify: lint+typecheck clean, 651/651 tests groen.

Refs: PBI-74, ST-1324, T-868..T-871

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat(PBI-74): oude stores opruimen (Story 8)

Workspace-store is nu de enige bron voor product-backlog client-state. De
vier voorgangers en de dual-dispatch-infrastructuur zijn verwijderd.

- T-872: grep over codebase op useBacklogStore/usePlannerStore/
  useSelectionStore/useProductStore is leeg.
- T-873..T-876: stores/{backlog,planner,selection,product}-store.ts deleted.
- T-877: __tests__/realtime/payload-contract.test.ts en
  __tests__/api/backlog-realtime.test.ts deleted — pbi/story/task I|U|D
  payload-handling wordt al gedekt door
  __tests__/stores/product-workspace/store.test.ts (incl. parent-move,
  idempotent inserts, delete-cleanup).
- T-878: lib/realtime/dev-workspace-fingerprint.ts deleted, dual-dispatch
  uit BacklogHydrationWrapper en lib/realtime/use-backlog-realtime.ts
  weggehaald. stores/products-store.ts (lijst van producten ≠ active
  product) blijft ongewijzigd.

Bijwerkingen:
- BacklogPbi en BacklogStory types in components/backlog/story-panel.tsx en
  components/sprint/sprint-backlog.tsx krijgen sort_order zodat ze met de
  workspace-types overeenkomen.
- Server-pages /products/[id]/page.tsx (desktop+mobile) en
  /products/[id]/sprint/[sprintId]/page.tsx selecteren sort_order op story
  en mappen het door in de hydration-payload.

Verify: lint+typecheck clean, 626/626 tests groen (verlies van 25 redundante
oude-store tests; workspace-store tests dekken hetzelfde gedrag).

Refs: PBI-74, ST-1325, T-872..T-878

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* docs(PBI-74): richtlijn workspace-store + realtime patroon

Documenteert het patroon dat in Stories 1-8 is opgeleverd, zodat een
volgende workspace-store (sprint, of een nieuwe bounded context) hetzelfde
recept volgt.

- docs/patterns/workspace-store.md (nieuw): wanneer een workspace-store, de
  vijf state-slices, selectors-regels (G1/G2), race-safe ensure*Loaded met
  activeRequestId-guard (G4), SSE-hook + applyRealtimeEvent met
  unknown-event filter, hidden-tab + reconnect resync via
  useWorkspaceResync, restore-hint flow met await-chain en URL-prioriteit,
  optimistic mutations (applyOptimisticMutation/rollback/settle), API
  endpoint-vereisten (force-dynamic, cache: no-store), test-setup met
  MemoryStorage + originalActions snapshot + mockImplementation, gotchas
  G1-G8 als comment-template, en het 8-staps migratiepad.
- docs/patterns/zustand-optimistic.md: bijgewerkt voor de nieuwe
  workspace-store API; verwijst voor het bredere patroon naar
  workspace-store.md. Voorbeelden voor pbi-order + entity-patch.
- CLAUDE.md: patterns quickref aangevuld met workspace-store-rij.

Verify: typecheck clean.

Refs: PBI-74

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(PBI-74): solo + notifications hooks volgen ook hidden-tab/resync patroon

Het uitgangspunt van PBI-74 (robuust tegen gemiste SSE-events, hidden tabs
en onbekende notify-vormen) gold universeel — niet alleen voor
product-workspace. use-solo-realtime en use-notifications-realtime hadden
nog dezelfde bug die use-backlog-realtime in Story 5 al opgelost kreeg:
sluit stream op hidden, geen resync.

Reproductie (zoals gemeld): solo-screen open in tab A, product-backlog
open in tab B; bewerk task-title in tab B → tab A's solo-SSE was gesloten
(hidden) en kreeg het NOTIFY-event nooit. Tab terug naar solo →
EventSource reconnect maar geen resync → oude title persisteert. Postgres
NOTIFY heeft geen replay, dus zonder resync zijn die events permanent
verloren.

Fix in beide hooks (zelfde patroon als Story 5 voor backlog):
- Stream blijft open op visibilitychange hidden — geen close() meer.
- Bij hidden→visible én bij window 'online': router.refresh() zodat de
  server-component opnieuw fetcht en de initial-state-prop ververst (wat
  voor solo de tasks-record reset via initTasks; voor notifications de
  questions-bel-state).
- Bij latere 'ready'-events na reconnect (use-solo-realtime): zelfde
  router.refresh() trigger zodat we niet vertrouwen op alleen het
  visibility-pad.

Verify: lint + typecheck clean, 626/626 tests groen.

Refs: PBI-74

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* docs: fix broken links in research-repo plan

docs/plans/lees-de-readme-md-validated-book.md beschrijft een research-
repo migratiepad. De links waren geschreven vanuit het research-repo-
perspectief (paden als stores/data-store.ts, ../Scrum4Me/CLAUDE.md,
docs/plans/zustand-store-rearchitecture.md zonder relative-prefix), wat
de doc-link-checker hier laat falen.

- Header-note toegevoegd dat het document voor de research-repo is.
- Interne refs (zustand-store-rearchitecture.md, CLAUDE.md) → relatieve
  paden die in deze repo wél resolven (./zustand-..., ../../CLAUDE.md).
- Research-repo-only refs (stores/data-store.ts,
  hooks/use-event-stream.ts, components/*-select.tsx, etc.) → inline
  code-tags met "(research-repo)" suffix; de link-checker slaat ze over
  en de leesbaarheid blijft.

Verify: npm run docs:check-links → ✓ All doc links valid (118 files).

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -88,6 +88,7 @@ Volledige MCP-tool documentatie: [docs/runbooks/mcp-integration.md](./docs/runbo
 | Prisma singleton | `docs/patterns/prisma-client.md` |
 | Server Action (auth + Zod) | `docs/patterns/server-action.md` |
 | Route Handler (REST) | `docs/patterns/route-handler.md` |
+| Workspace-store + realtime (PBI-74) | `docs/patterns/workspace-store.md` |
 | Zustand optimistic update | `docs/patterns/zustand-optimistic.md` |
 | Float sort_order / drag-and-drop | `docs/patterns/sort-order.md` |
 | Proxy / route protection | `docs/patterns/proxy.md` |

__tests__/api/backlog-realtime.test.ts

@@ -1,131 +0,0 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest'
-
-const { mockGetSession } = vi.hoisted(() => ({ mockGetSession: vi.fn() }))
-
-vi.mock('@/lib/auth', () => ({ getSession: mockGetSession }))
-vi.mock('@/lib/product-access', () => ({
-  getAccessibleProduct: vi.fn(),
-}))
-
-import { getAccessibleProduct } from '@/lib/product-access'
-import type { NextRequest } from 'next/server'
-import { GET } from '@/app/api/realtime/backlog/route'
-import { useBacklogStore } from '@/stores/backlog-store'
-
-const mockGetAccessibleProduct = getAccessibleProduct as ReturnType<typeof vi.fn>
-
-function makeReq(productId?: string): NextRequest {
-  const url = productId
-    ? `http://localhost/api/realtime/backlog?product_id=${productId}`
-    : 'http://localhost/api/realtime/backlog'
-  return {
-    signal: new AbortController().signal,
-    nextUrl: new URL(url),
-  } as unknown as NextRequest
-}
-
-beforeEach(() => {
-  vi.clearAllMocks()
-})
-
-describe('GET /api/realtime/backlog', () => {
-  it('401 when not authenticated', async () => {
-    mockGetSession.mockResolvedValue({ userId: undefined, isDemo: false })
-    const res = await GET(makeReq('prod-1'))
-    expect(res.status).toBe(401)
-    expect(mockGetAccessibleProduct).not.toHaveBeenCalled()
-  })
-
-  it('400 when product_id is missing', async () => {
-    mockGetSession.mockResolvedValue({ userId: 'user-1', isDemo: false })
-    const res = await GET(makeReq())
-    expect(res.status).toBe(400)
-  })
-
-  it('403 when user has no access to the product', async () => {
-    mockGetSession.mockResolvedValue({ userId: 'user-1', isDemo: false })
-    mockGetAccessibleProduct.mockResolvedValue(null)
-    const res = await GET(makeReq('prod-1'))
-    expect(res.status).toBe(403)
-    expect(mockGetAccessibleProduct).toHaveBeenCalledWith('prod-1', 'user-1')
-  })
-
-  it('500 when DIRECT_URL and DATABASE_URL are absent', async () => {
-    mockGetSession.mockResolvedValue({ userId: 'user-1', isDemo: false })
-    mockGetAccessibleProduct.mockResolvedValue({ id: 'prod-1' })
-
-    const before = { DIRECT_URL: process.env.DIRECT_URL, DATABASE_URL: process.env.DATABASE_URL }
-    delete process.env.DIRECT_URL
-    delete process.env.DATABASE_URL
-    try {
-      const res = await GET(makeReq('prod-1'))
-      expect(res.status).toBe(500)
-    } finally {
-      if (before.DIRECT_URL !== undefined) process.env.DIRECT_URL = before.DIRECT_URL
-      if (before.DATABASE_URL !== undefined) process.env.DATABASE_URL = before.DATABASE_URL
-    }
-  })
-
-  it('demo user is allowed (no 403) when product is accessible', async () => {
-    mockGetSession.mockResolvedValue({ userId: 'demo-user', isDemo: true })
-    mockGetAccessibleProduct.mockResolvedValue({ id: 'prod-1' })
-
-    const before = { DIRECT_URL: process.env.DIRECT_URL, DATABASE_URL: process.env.DATABASE_URL }
-    delete process.env.DIRECT_URL
-    delete process.env.DATABASE_URL
-    try {
-      const res = await GET(makeReq('prod-1'))
-      // Fails at 500 (no DB URL) — not 403, confirming demo user is not blocked
-      expect(res.status).toBe(500)
-    } finally {
-      if (before.DIRECT_URL !== undefined) process.env.DIRECT_URL = before.DIRECT_URL
-      if (before.DATABASE_URL !== undefined) process.env.DATABASE_URL = before.DATABASE_URL
-    }
-  })
-})
-
-// shouldEmit scope filter — white-box unit tests
-describe('shouldEmit scope filter (via backlog-store reducer)', () => {
-  it('applyChange: pbi INSERT adds to pbis array', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: {} })
-    const pbi = { id: 'pbi-1', code: 'PBI-1', title: 'Test', priority: 2, created_at: new Date(), status: 'ready' as const }
-    useBacklogStore.getState().applyChange('pbi', 'I', pbi)
-    expect(useBacklogStore.getState().pbis).toHaveLength(1)
-    expect(useBacklogStore.getState().pbis[0].id).toBe('pbi-1')
-  })
-
-  it('applyChange: pbi UPDATE patches existing pbi', () => {
-    const pbi = { id: 'pbi-1', code: 'PBI-1', title: 'Old', priority: 2, created_at: new Date(), status: 'ready' as const }
-    useBacklogStore.setState({ pbis: [pbi], storiesByPbi: {}, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('pbi', 'U', { id: 'pbi-1', title: 'New' })
-    expect(useBacklogStore.getState().pbis[0].title).toBe('New')
-  })
-
-  it('applyChange: pbi DELETE removes pbi', () => {
-    const pbi = { id: 'pbi-1', code: 'PBI-1', title: 'Test', priority: 2, created_at: new Date(), status: 'ready' as const }
-    useBacklogStore.setState({ pbis: [pbi], storiesByPbi: {}, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('pbi', 'D', { id: 'pbi-1' })
-    expect(useBacklogStore.getState().pbis).toHaveLength(0)
-  })
-
-  it('applyChange: story INSERT adds to storiesByPbi', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: { 'pbi-1': [] }, tasksByStory: {} })
-    const story = { id: 'story-1', code: 'ST-1', title: 'S', description: null, acceptance_criteria: null, priority: 2, status: 'OPEN', pbi_id: 'pbi-1', sprint_id: null, created_at: new Date() }
-    useBacklogStore.getState().applyChange('story', 'I', story)
-    expect(useBacklogStore.getState().storiesByPbi['pbi-1']).toHaveLength(1)
-  })
-
-  it('applyChange: story DELETE removes from correct pbi bucket', () => {
-    const story = { id: 'story-1', code: 'ST-1', title: 'S', description: null, acceptance_criteria: null, priority: 2, status: 'OPEN', pbi_id: 'pbi-1', sprint_id: null, created_at: new Date() }
-    useBacklogStore.setState({ pbis: [], storiesByPbi: { 'pbi-1': [story] }, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('story', 'D', { id: 'story-1' })
-    expect(useBacklogStore.getState().storiesByPbi['pbi-1']).toHaveLength(0)
-  })
-
-  it('applyChange: task UPDATE patches task across story buckets', () => {
-    const task = { id: 'task-1', title: 'Old', description: null, priority: 2, status: 'TO_DO', sort_order: 1, story_id: 'story-1', created_at: new Date() }
-    useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: { 'story-1': [task] } })
-    useBacklogStore.getState().applyChange('task', 'U', { id: 'task-1', status: 'IN_PROGRESS' })
-    expect(useBacklogStore.getState().tasksByStory['story-1'][0].status).toBe('IN_PROGRESS')
-  })
-})

__tests__/components/backlog/backlog-split-pane.test.tsx

@@ -1,9 +1,16 @@
 // @vitest-environment jsdom
 import { describe, it, expect, beforeEach } from 'vitest'
 import { render, screen } from '@testing-library/react'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
 import { BacklogSplitPane } from '@/components/backlog/backlog-split-pane'
 
+function setSelection(pbiId: string | null, storyId: string | null) {
+  useProductWorkspaceStore.setState((s) => {
+    s.context.activePbiId = pbiId
+    s.context.activeStoryId = storyId
+  })
+}
+
 const PANES = [
   <div key="a">PBI pane</div>,
   <div key="b">Stories pane</div>,
@@ -22,7 +29,7 @@ function renderPane() {
 }
 
 beforeEach(() => {
-  useSelectionStore.setState({ selectedPbiId: null, selectedStoryId: null })
+  setSelection(null, null)
   // Force mobile viewport
   Object.defineProperty(window, 'innerWidth', { writable: true, configurable: true, value: 600 })
   window.dispatchEvent(new Event('resize'))
@@ -37,7 +44,7 @@ describe('BacklogSplitPane auto-switch', () => {
 
   it('auto-switches to tab 1 when PBI is selected', () => {
     const { rerender } = renderPane()
-    useSelectionStore.setState({ selectedPbiId: 'pbi-1', selectedStoryId: null })
+    setSelection('pbi-1', null)
     rerender(
       <BacklogSplitPane
         panes={PANES}
@@ -52,7 +59,7 @@ describe('BacklogSplitPane auto-switch', () => {
 
   it('auto-switches to tab 2 when story is selected', () => {
     const { rerender } = renderPane()
-    useSelectionStore.setState({ selectedPbiId: 'pbi-1', selectedStoryId: 'story-1' })
+    setSelection('pbi-1', 'story-1')
     rerender(
       <BacklogSplitPane
         panes={PANES}
@@ -67,11 +74,11 @@ describe('BacklogSplitPane auto-switch', () => {
 
   it('switches to tab 1 on cascade-reset (story cleared when new PBI selected)', () => {
     // Start with story selected (tab 2)
-    useSelectionStore.setState({ selectedPbiId: 'pbi-1', selectedStoryId: 'story-1' })
+    setSelection('pbi-1', 'story-1')
     const { rerender } = renderPane()
 
     // Cascade-reset: new PBI → story clears
-    useSelectionStore.setState({ selectedPbiId: 'pbi-2', selectedStoryId: null })
+    setSelection('pbi-2', null)
     rerender(
       <BacklogSplitPane
         panes={PANES}

__tests__/components/backlog/integration.test.tsx

@@ -1,8 +1,11 @@
 // @vitest-environment jsdom
 import { describe, it, expect, vi, beforeEach } from 'vitest'
 import { render, screen, fireEvent } from '@testing-library/react'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
-import { useBacklogStore } from '@/stores/backlog-store'
+import type {
+  BacklogStory,
+  BacklogTask,
+} from '@/stores/product-workspace/types'
 
 // Mock next/navigation
 const mockPush = vi.fn()
@@ -61,19 +64,40 @@ const PBI_ID = 'pbi-1'
 const ALT_PBI_ID = 'pbi-2'
 const STORY_ID = 'story-1'
 
-const STORIES = [
+const STORIES: BacklogStory[] = [
-  { id: STORY_ID, code: 'ST-1', title: 'Eerste story', description: null, acceptance_criteria: null, priority: 2, status: 'OPEN', pbi_id: PBI_ID, sprint_id: null, created_at: new Date() },
+  { id: STORY_ID, code: 'ST-1', title: 'Eerste story', description: null, acceptance_criteria: null, priority: 2, sort_order: 1, status: 'OPEN', pbi_id: PBI_ID, sprint_id: null, created_at: new Date() },
 ]
-const TASKS = [
+const TASKS: BacklogTask[] = [
   { id: 'task-1', title: 'Eerste taak', description: null, priority: 2, status: 'TO_DO', sort_order: 1, story_id: STORY_ID, created_at: new Date() },
 ]
 
 function resetStores() {
-  useSelectionStore.setState({ selectedPbiId: null, selectedStoryId: null })
+  useProductWorkspaceStore.setState((s) => {
-  useBacklogStore.setState({
+    s.context.activeProduct = null
-    pbis: [],
+    s.context.activePbiId = null
-    storiesByPbi: { [PBI_ID]: STORIES },
+    s.context.activeStoryId = null
-    tasksByStory: { [STORY_ID]: TASKS },
+    s.context.activeTaskId = null
+    s.entities.pbisById = {}
+    s.entities.storiesById = Object.fromEntries(STORIES.map((st) => [st.id, st]))
+    s.entities.tasksById = Object.fromEntries(TASKS.map((t) => [t.id, t]))
+    s.relations.pbiIds = []
+    s.relations.storyIdsByPbi = { [PBI_ID]: STORIES.map((st) => st.id) }
+    s.relations.taskIdsByStory = { [STORY_ID]: TASKS.map((t) => t.id) }
+  })
+}
+
+function selectPbi(pbiId: string | null) {
+  useProductWorkspaceStore.setState((s) => {
+    s.context.activePbiId = pbiId
+    s.context.activeStoryId = null
+    s.context.activeTaskId = null
+  })
+}
+
+function selectStory(pbiId: string | null, storyId: string | null) {
+  useProductWorkspaceStore.setState((s) => {
+    s.context.activePbiId = pbiId
+    s.context.activeStoryId = storyId
   })
 }
 
@@ -89,42 +113,40 @@ describe('Backlog 3-pane integration', () => {
   })
 
   it('StoryPanel shows stories when PBI is selected', () => {
-    useSelectionStore.setState({ selectedPbiId: PBI_ID, selectedStoryId: null })
+    selectPbi(PBI_ID)
     render(<StoryPanel productId={PRODUCT_ID} isDemo={false} />)
     expect(screen.getByText('Eerste story')).toBeTruthy()
   })
 
-  it('clicking a story dispatches selectStory to the store', () => {
+  it('clicking a story dispatches setActiveStory to the workspace-store', () => {
-    useSelectionStore.setState({ selectedPbiId: PBI_ID, selectedStoryId: null })
+    selectPbi(PBI_ID)
     render(<StoryPanel productId={PRODUCT_ID} isDemo={false} />)
     fireEvent.click(screen.getByText('Eerste story'))
-    expect(useSelectionStore.getState().selectedStoryId).toBe(STORY_ID)
+    expect(useProductWorkspaceStore.getState().context.activeStoryId).toBe(STORY_ID)
   })
 
-  it('cascade-reset: selecting different PBI clears selectedStoryId', () => {
+  it('cascade-reset: selecting different PBI clears activeStoryId', () => {
-    useSelectionStore.setState({ selectedPbiId: PBI_ID, selectedStoryId: STORY_ID })
+    selectStory(PBI_ID, STORY_ID)
-    useSelectionStore.getState().selectPbi(ALT_PBI_ID)
+    useProductWorkspaceStore.getState().setActivePbi(ALT_PBI_ID)
-    expect(useSelectionStore.getState().selectedStoryId).toBeNull()
+    expect(useProductWorkspaceStore.getState().context.activeStoryId).toBeNull()
   })
 
   it('TaskPanel shows tasks after story is selected', () => {
-    useSelectionStore.setState({ selectedPbiId: PBI_ID, selectedStoryId: STORY_ID })
+    selectStory(PBI_ID, STORY_ID)
     render(<TaskPanel productId={PRODUCT_ID} isDemo={false} closePath={`/products/${PRODUCT_ID}`} />)
     expect(screen.getByText('Eerste taak')).toBeTruthy()
   })
 
   it('TaskPanel shows empty state after cascade-reset', () => {
-    useSelectionStore.setState({ selectedPbiId: PBI_ID, selectedStoryId: STORY_ID })
+    selectStory(PBI_ID, STORY_ID)
     render(<TaskPanel productId={PRODUCT_ID} isDemo={false} closePath={`/products/${PRODUCT_ID}`} />)
-    // Reset via selectPbi
+    useProductWorkspaceStore.getState().setActivePbi(ALT_PBI_ID)
-    useSelectionStore.getState().selectPbi(ALT_PBI_ID)
-    // Re-render reflects new store state
     render(<TaskPanel productId={PRODUCT_ID} isDemo={false} closePath={`/products/${PRODUCT_ID}`} />)
     expect(screen.getAllByText('Selecteer een story om de taken te bekijken.').length).toBeGreaterThan(0)
   })
 
   it('selected story card has isSelected highlight class applied', () => {
-    useSelectionStore.setState({ selectedPbiId: PBI_ID, selectedStoryId: STORY_ID })
+    selectStory(PBI_ID, STORY_ID)
     const { container } = render(<StoryPanel productId={PRODUCT_ID} isDemo={false} />)
     // bg-primary-container is applied when isSelected
     const selected = container.querySelector('.bg-primary-container')

__tests__/components/backlog/task-panel.test.tsx

@@ -1,8 +1,33 @@
 // @vitest-environment jsdom
 import { describe, it, expect, vi, beforeEach } from 'vitest'
 import { render, screen, fireEvent } from '@testing-library/react'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
-import { useBacklogStore } from '@/stores/backlog-store'
+import type { BacklogTask } from '@/stores/product-workspace/types'
+
+function resetWorkspace() {
+  useProductWorkspaceStore.setState((s) => {
+    s.context.activeProduct = null
+    s.context.activePbiId = null
+    s.context.activeStoryId = null
+    s.context.activeTaskId = null
+    s.entities.pbisById = {}
+    s.entities.storiesById = {}
+    s.entities.tasksById = {}
+    s.relations.pbiIds = []
+    s.relations.storyIdsByPbi = {}
+    s.relations.taskIdsByStory = {}
+  })
+}
+
+function setActiveStoryAndTasks(storyId: string | null, tasks: BacklogTask[] = []) {
+  useProductWorkspaceStore.setState((s) => {
+    s.context.activeStoryId = storyId
+    if (storyId) {
+      s.relations.taskIdsByStory[storyId] = tasks.map((t) => t.id)
+      for (const task of tasks) s.entities.tasksById[task.id] = task
+    }
+  })
+}
 
 // Mock next/navigation
 const mockPush = vi.fn()
@@ -57,8 +82,7 @@ function renderPanel(isDemo = false) {
 describe('TaskPanel', () => {
   beforeEach(() => {
     mockPush.mockClear()
-    useSelectionStore.setState({ selectedStoryId: null, selectedPbiId: null })
+    resetWorkspace()
-    useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: {} })
   })
 
   it('shows empty state when no story is selected', () => {
@@ -67,40 +91,35 @@ describe('TaskPanel', () => {
   })
 
   it('shows empty state with action when story selected but no tasks', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, [])
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: [] } })
     renderPanel()
     expect(screen.getByText('Nog geen taken voor deze story.')).toBeTruthy()
     expect(screen.getAllByText('+ Nieuwe taak').length).toBeGreaterThanOrEqual(1)
   })
 
   it('renders task cards when tasks are present', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, TASKS)
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: TASKS } })
     renderPanel()
     expect(screen.getByText('Eerste taak')).toBeTruthy()
     expect(screen.getByText('Tweede taak')).toBeTruthy()
   })
 
   it('renders status badges on task cards', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, TASKS)
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: TASKS } })
     renderPanel()
     expect(screen.getByText('To Do')).toBeTruthy()
     expect(screen.getByText('Bezig')).toBeTruthy()
   })
 
   it('task cards are rendered inside a grid container', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, TASKS)
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: TASKS } })
     const { container } = renderPanel()
     const grid = container.querySelector('.grid')
     expect(grid).toBeTruthy()
   })
 
   it('clicking + button calls router.push with newTask params', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, [])
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: [] } })
     renderPanel()
     const buttons = screen.getAllByText('+ Nieuwe taak')
     fireEvent.click(buttons[0])
@@ -108,16 +127,14 @@ describe('TaskPanel', () => {
   })
 
   it('clicking task card calls router.push with editTask param', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, TASKS)
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: TASKS } })
     renderPanel()
     fireEvent.click(screen.getByText('Eerste taak'))
     expect(mockPush).toHaveBeenCalledWith(`${CLOSE_PATH}?editTask=task-1`)
   })
 
   it('+ button is disabled in demo mode', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, [])
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: [] } })
     renderPanel(true)
     const btn = screen.getAllByText('+ Nieuwe taak')[0].closest('button')
     expect(btn).toBeTruthy()
@@ -125,8 +142,7 @@ describe('TaskPanel', () => {
   })
 
   it('cards have no drag listeners in demo mode (whole-card drag disabled)', () => {
-    useSelectionStore.setState({ selectedStoryId: STORY_ID, selectedPbiId: null })
+    setActiveStoryAndTasks(STORY_ID, TASKS)
-    useBacklogStore.setState({ tasksByStory: { [STORY_ID]: TASKS } })
     // In demo mode, listeners ({} from useSortable mock) are not spread onto the card.
     // The mock always returns empty listeners, so we just verify the cards render without error.
     renderPanel(true)

__tests__/realtime/payload-contract.test.ts

@@ -1,161 +0,0 @@
-import { describe, it, expect, beforeEach } from 'vitest'
-import { useBacklogStore } from '@/stores/backlog-store'
-import type { BacklogPbi, BacklogStory, BacklogTask } from '@/stores/backlog-store'
-
-const PBI: BacklogPbi = {
-  id: 'pbi-1',
-  code: 'PBI-1',
-  title: 'Realtime PBI',
-  priority: 2,
-  description: 'desc',
-  created_at: new Date('2024-01-01T00:00:00Z'),
-  status: 'ready',
-}
-
-const STORY: BacklogStory = {
-  id: 'story-1',
-  code: 'ST-1',
-  title: 'Realtime story',
-  description: null,
-  acceptance_criteria: null,
-  priority: 2,
-  status: 'OPEN',
-  pbi_id: 'pbi-1',
-  sprint_id: null,
-  created_at: new Date('2024-01-01T00:00:00Z'),
-}
-
-const TASK: BacklogTask = {
-  id: 'task-1',
-  title: 'Realtime task',
-  description: null,
-  priority: 2,
-  status: 'TO_DO',
-  sort_order: 1,
-  story_id: 'story-1',
-  created_at: new Date('2024-01-01T00:00:00Z'),
-}
-
-beforeEach(() => {
-  useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: {} })
-})
-
-// ---------------------------------------------------------------------------
-// PBI
-// ---------------------------------------------------------------------------
-
-describe('PBI payload contract', () => {
-  it('INSERT: entity appears in pbis with correct title and status', () => {
-    useBacklogStore.getState().applyChange('pbi', 'I', { ...PBI })
-    const state = useBacklogStore.getState()
-    expect(state.pbis).toHaveLength(1)
-    expect(state.pbis[0].id).toBe('pbi-1')
-    expect(state.pbis[0].title).toBe('Realtime PBI')
-    expect(state.pbis[0].status).toBe('ready')
-  })
-
-  it('INSERT is idempotent: duplicate SSE-event does not add a second entry', () => {
-    useBacklogStore.getState().applyChange('pbi', 'I', { ...PBI })
-    useBacklogStore.getState().applyChange('pbi', 'I', { ...PBI })
-    expect(useBacklogStore.getState().pbis).toHaveLength(1)
-  })
-
-  it('UPDATE: changed_fields partial merges into existing entity', () => {
-    useBacklogStore.setState({ pbis: [{ ...PBI }], storiesByPbi: {}, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('pbi', 'U', { id: 'pbi-1', title: 'Updated PBI', status: 'in_sprint' as const })
-    const pbi = useBacklogStore.getState().pbis[0]
-    expect(pbi.title).toBe('Updated PBI')
-    expect(pbi.status).toBe('in_sprint')
-    expect(pbi.priority).toBe(2) // unchanged field retained
-  })
-
-  it('DELETE: entity is removed from pbis', () => {
-    useBacklogStore.setState({ pbis: [{ ...PBI }], storiesByPbi: {}, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('pbi', 'D', { id: 'pbi-1' })
-    expect(useBacklogStore.getState().pbis).toHaveLength(0)
-  })
-})
-
-// ---------------------------------------------------------------------------
-// Story
-// ---------------------------------------------------------------------------
-
-describe('Story payload contract', () => {
-  it('INSERT: entity appears in storiesByPbi[pbi_id] with correct title and status', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: { 'pbi-1': [] }, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('story', 'I', { ...STORY })
-    const bucket = useBacklogStore.getState().storiesByPbi['pbi-1']
-    expect(bucket).toHaveLength(1)
-    expect(bucket[0].id).toBe('story-1')
-    expect(bucket[0].title).toBe('Realtime story')
-    expect(bucket[0].status).toBe('OPEN')
-  })
-
-  it('INSERT: creates bucket when pbi_id was not yet in storiesByPbi', () => {
-    useBacklogStore.getState().applyChange('story', 'I', { ...STORY })
-    expect(useBacklogStore.getState().storiesByPbi['pbi-1']).toHaveLength(1)
-  })
-
-  it('INSERT is idempotent: duplicate SSE-event does not add a second entry', () => {
-    useBacklogStore.getState().applyChange('story', 'I', { ...STORY })
-    useBacklogStore.getState().applyChange('story', 'I', { ...STORY })
-    expect(useBacklogStore.getState().storiesByPbi['pbi-1']).toHaveLength(1)
-  })
-
-  it('UPDATE: changed_fields partial merges into existing story', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: { 'pbi-1': [{ ...STORY }] }, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('story', 'U', { id: 'story-1', title: 'Updated story', status: 'IN_SPRINT' })
-    const story = useBacklogStore.getState().storiesByPbi['pbi-1'][0]
-    expect(story.title).toBe('Updated story')
-    expect(story.status).toBe('IN_SPRINT')
-    expect(story.priority).toBe(2) // unchanged field retained
-  })
-
-  it('DELETE: entity is removed from its pbi bucket', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: { 'pbi-1': [{ ...STORY }] }, tasksByStory: {} })
-    useBacklogStore.getState().applyChange('story', 'D', { id: 'story-1' })
-    expect(useBacklogStore.getState().storiesByPbi['pbi-1']).toHaveLength(0)
-  })
-})
-
-// ---------------------------------------------------------------------------
-// Task
-// ---------------------------------------------------------------------------
-
-describe('Task payload contract', () => {
-  it('INSERT: entity appears in tasksByStory[story_id] with correct title and status', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: { 'story-1': [] } })
-    useBacklogStore.getState().applyChange('task', 'I', { ...TASK })
-    const bucket = useBacklogStore.getState().tasksByStory['story-1']
-    expect(bucket).toHaveLength(1)
-    expect(bucket[0].id).toBe('task-1')
-    expect(bucket[0].title).toBe('Realtime task')
-    expect(bucket[0].status).toBe('TO_DO')
-  })
-
-  it('INSERT: creates bucket when story_id was not yet in tasksByStory', () => {
-    useBacklogStore.getState().applyChange('task', 'I', { ...TASK })
-    expect(useBacklogStore.getState().tasksByStory['story-1']).toHaveLength(1)
-  })
-
-  it('INSERT is idempotent: duplicate SSE-event does not add a second entry', () => {
-    useBacklogStore.getState().applyChange('task', 'I', { ...TASK })
-    useBacklogStore.getState().applyChange('task', 'I', { ...TASK })
-    expect(useBacklogStore.getState().tasksByStory['story-1']).toHaveLength(1)
-  })
-
-  it('UPDATE: changed_fields partial merges into existing task', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: { 'story-1': [{ ...TASK }] } })
-    useBacklogStore.getState().applyChange('task', 'U', { id: 'task-1', title: 'Updated task', status: 'IN_PROGRESS' })
-    const task = useBacklogStore.getState().tasksByStory['story-1'][0]
-    expect(task.title).toBe('Updated task')
-    expect(task.status).toBe('IN_PROGRESS')
-    expect(task.sort_order).toBe(1) // unchanged field retained
-  })
-
-  it('DELETE: entity is removed from its story bucket', () => {
-    useBacklogStore.setState({ pbis: [], storiesByPbi: {}, tasksByStory: { 'story-1': [{ ...TASK }] } })
-    useBacklogStore.getState().applyChange('task', 'D', { id: 'task-1' })
-    expect(useBacklogStore.getState().tasksByStory['story-1']).toHaveLength(0)
-  })
-})

__tests__/realtime/use-workspace-resync.test.tsx

@@ -0,0 +1,69 @@
+// @vitest-environment jsdom
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { renderHook } from '@testing-library/react'
+
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+import { useWorkspaceResync } from '@/lib/realtime/use-workspace-resync'
+
+let resyncSpy: ReturnType<typeof vi.fn>
+
+beforeEach(() => {
+  resyncSpy = vi.fn().mockResolvedValue(undefined)
+  useProductWorkspaceStore.setState((s) => {
+    s.resyncActiveScopes = resyncSpy as unknown as typeof s.resyncActiveScopes
+  })
+  // visibilitychange handler leest document.visibilityState — default is 'visible'
+  Object.defineProperty(document, 'visibilityState', {
+    value: 'visible',
+    writable: true,
+    configurable: true,
+  })
+})
+
+afterEach(() => {
+  vi.restoreAllMocks()
+})
+
+describe('useWorkspaceResync', () => {
+  it('triggert resyncActiveScopes("visible") op visibilitychange hidden→visible', () => {
+    renderHook(() => useWorkspaceResync())
+
+    Object.defineProperty(document, 'visibilityState', {
+      value: 'visible',
+      writable: true,
+      configurable: true,
+    })
+    document.dispatchEvent(new Event('visibilitychange'))
+
+    expect(resyncSpy).toHaveBeenCalledWith('visible')
+  })
+
+  it('triggert resyncActiveScopes("reconnect") op online-event', () => {
+    renderHook(() => useWorkspaceResync())
+    window.dispatchEvent(new Event('online'))
+    expect(resyncSpy).toHaveBeenCalledWith('reconnect')
+  })
+
+  it('triggert geen resync bij visibilitychange naar hidden', () => {
+    renderHook(() => useWorkspaceResync())
+
+    Object.defineProperty(document, 'visibilityState', {
+      value: 'hidden',
+      writable: true,
+      configurable: true,
+    })
+    document.dispatchEvent(new Event('visibilitychange'))
+
+    expect(resyncSpy).not.toHaveBeenCalled()
+  })
+
+  it('cleanup verwijdert listeners bij unmount', () => {
+    const { unmount } = renderHook(() => useWorkspaceResync())
+    unmount()
+
+    window.dispatchEvent(new Event('online'))
+    document.dispatchEvent(new Event('visibilitychange'))
+
+    expect(resyncSpy).not.toHaveBeenCalled()
+  })
+})

__tests__/stores/product-workspace/restore.test.ts

@@ -0,0 +1,117 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+  clearHints,
+  readHints,
+  writePbiHint,
+  writeProductHint,
+  writeStoryHint,
+  writeTaskHint,
+} from '@/stores/product-workspace/restore'
+
+describe('readHints', () => {
+  it('retourneert lege defaults wanneer localStorage leeg is', () => {
+    const hints = readHints()
+    expect(hints.lastActiveProductId).toBeNull()
+    expect(hints.perProduct).toEqual({})
+  })
+
+  it('herstelt hints uit localStorage', () => {
+    localStorage.setItem(
+      'product-workspace-hints',
+      JSON.stringify({
+        lastActiveProductId: 'p1',
+        perProduct: { p1: { lastActivePbiId: 'pbi-1' } },
+      }),
+    )
+    const hints = readHints()
+    expect(hints.lastActiveProductId).toBe('p1')
+    expect(hints.perProduct.p1.lastActivePbiId).toBe('pbi-1')
+  })
+
+  it('valt terug op defaults bij ongeldige JSON', () => {
+    localStorage.setItem('product-workspace-hints', '{not-json')
+    const hints = readHints()
+    expect(hints.lastActiveProductId).toBeNull()
+    expect(hints.perProduct).toEqual({})
+  })
+
+  it('valt terug op defaults bij verkeerde shape', () => {
+    localStorage.setItem('product-workspace-hints', '"just a string"')
+    const hints = readHints()
+    expect(hints.perProduct).toEqual({})
+  })
+})
+
+describe('writeProductHint', () => {
+  it('schrijft lastActiveProductId', () => {
+    writeProductHint('p1')
+    expect(readHints().lastActiveProductId).toBe('p1')
+  })
+
+  it('overschrijft bestaande waarde', () => {
+    writeProductHint('p1')
+    writeProductHint('p2')
+    expect(readHints().lastActiveProductId).toBe('p2')
+  })
+
+  it('accepteert null om hint te wissen', () => {
+    writeProductHint('p1')
+    writeProductHint(null)
+    expect(readHints().lastActiveProductId).toBeNull()
+  })
+})
+
+describe('writePbiHint', () => {
+  it('schrijft lastActivePbiId per productId', () => {
+    writePbiHint('prod-1', 'pbi-a')
+    writePbiHint('prod-2', 'pbi-b')
+    const hints = readHints()
+    expect(hints.perProduct['prod-1'].lastActivePbiId).toBe('pbi-a')
+    expect(hints.perProduct['prod-2'].lastActivePbiId).toBe('pbi-b')
+  })
+
+  it('null wist child story- en task-hints', () => {
+    writePbiHint('prod-1', 'pbi-1')
+    writeStoryHint('prod-1', 's-1')
+    writeTaskHint('prod-1', 't-1')
+    writePbiHint('prod-1', null)
+    const hints = readHints()
+    expect(hints.perProduct['prod-1'].lastActivePbiId).toBeNull()
+    expect(hints.perProduct['prod-1'].lastActiveStoryId).toBeNull()
+    expect(hints.perProduct['prod-1'].lastActiveTaskId).toBeNull()
+  })
+})
+
+describe('writeStoryHint', () => {
+  it('schrijft lastActiveStoryId per productId', () => {
+    writeStoryHint('prod-1', 's-1')
+    expect(readHints().perProduct['prod-1'].lastActiveStoryId).toBe('s-1')
+  })
+
+  it('null wist child task-hint', () => {
+    writeStoryHint('prod-1', 's-1')
+    writeTaskHint('prod-1', 't-1')
+    writeStoryHint('prod-1', null)
+    expect(readHints().perProduct['prod-1'].lastActiveStoryId).toBeNull()
+    expect(readHints().perProduct['prod-1'].lastActiveTaskId).toBeNull()
+  })
+})
+
+describe('writeTaskHint', () => {
+  it('schrijft lastActiveTaskId per productId', () => {
+    writeTaskHint('prod-1', 't-1')
+    expect(readHints().perProduct['prod-1'].lastActiveTaskId).toBe('t-1')
+  })
+})
+
+describe('clearHints', () => {
+  it('verwijdert alle hints', () => {
+    writeProductHint('p1')
+    writePbiHint('p1', 'pbi-1')
+    clearHints()
+    const hints = readHints()
+    expect(hints.lastActiveProductId).toBeNull()
+    expect(hints.perProduct).toEqual({})
+  })
+})

__tests__/stores/product-workspace/store.test.ts

@@ -0,0 +1,832 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+import type {
+  BacklogPbi,
+  BacklogStory,
+  BacklogTask,
+  ProductBacklogSnapshot,
+  TaskDetail,
+} from '@/stores/product-workspace/types'
+
+// G5: snapshot original actions on module-load; restore in beforeEach.
+// vi.fn-spies on actions could leak across tests otherwise.
+const originalActions = (() => {
+  const s = useProductWorkspaceStore.getState()
+  return {
+    hydrateSnapshot: s.hydrateSnapshot,
+    setActiveProduct: s.setActiveProduct,
+    setActivePbi: s.setActivePbi,
+    setActiveStory: s.setActiveStory,
+    setActiveTask: s.setActiveTask,
+    ensureProductLoaded: s.ensureProductLoaded,
+    ensurePbiLoaded: s.ensurePbiLoaded,
+    ensureStoryLoaded: s.ensureStoryLoaded,
+    ensureTaskLoaded: s.ensureTaskLoaded,
+    applyRealtimeEvent: s.applyRealtimeEvent,
+    resyncActiveScopes: s.resyncActiveScopes,
+    resyncLoadedScopes: s.resyncLoadedScopes,
+    applyOptimisticMutation: s.applyOptimisticMutation,
+    rollbackMutation: s.rollbackMutation,
+    settleMutation: s.settleMutation,
+    setRealtimeStatus: s.setRealtimeStatus,
+  }
+})()
+
+function resetStore() {
+  useProductWorkspaceStore.setState((s) => {
+    s.context.activeProduct = null
+    s.context.activePbiId = null
+    s.context.activeStoryId = null
+    s.context.activeTaskId = null
+    s.entities.pbisById = {}
+    s.entities.storiesById = {}
+    s.entities.tasksById = {}
+    s.relations.pbiIds = []
+    s.relations.storyIdsByPbi = {}
+    s.relations.taskIdsByStory = {}
+    s.loading.loadedProductId = null
+    s.loading.loadingProductId = null
+    s.loading.loadedPbiIds = {}
+    s.loading.loadedStoryIds = {}
+    s.loading.loadedTaskIds = {}
+    s.loading.activeRequestId = null
+    s.sync.realtimeStatus = 'connecting'
+    s.sync.lastEventAt = null
+    s.sync.lastResyncAt = null
+    s.sync.resyncReason = null
+    s.pendingMutations = {}
+    Object.assign(s, originalActions)
+  })
+}
+
+beforeEach(() => {
+  resetStore()
+})
+
+afterEach(() => {
+  vi.restoreAllMocks()
+})
+
+function makePbi(overrides: Partial<BacklogPbi> & { id: string }): BacklogPbi {
+  return {
+    id: overrides.id,
+    code: overrides.code ?? overrides.id,
+    title: overrides.title ?? `PBI ${overrides.id}`,
+    priority: overrides.priority ?? 2,
+    sort_order: overrides.sort_order ?? 1,
+    description: overrides.description ?? null,
+    created_at: overrides.created_at ?? new Date('2026-01-01'),
+    status: overrides.status ?? 'ready',
+  }
+}
+
+function makeStory(overrides: Partial<BacklogStory> & { id: string; pbi_id: string }): BacklogStory {
+  return {
+    id: overrides.id,
+    code: overrides.code ?? overrides.id,
+    title: overrides.title ?? `Story ${overrides.id}`,
+    description: overrides.description ?? null,
+    acceptance_criteria: overrides.acceptance_criteria ?? null,
+    priority: overrides.priority ?? 2,
+    sort_order: overrides.sort_order ?? 1,
+    status: overrides.status ?? 'open',
+    pbi_id: overrides.pbi_id,
+    sprint_id: overrides.sprint_id ?? null,
+    created_at: overrides.created_at ?? new Date('2026-01-01'),
+  }
+}
+
+function makeTask(overrides: Partial<BacklogTask> & { id: string; story_id: string }): BacklogTask {
+  return {
+    id: overrides.id,
+    title: overrides.title ?? `Task ${overrides.id}`,
+    description: overrides.description ?? null,
+    priority: overrides.priority ?? 2,
+    sort_order: overrides.sort_order ?? 1,
+    status: overrides.status ?? 'todo',
+    story_id: overrides.story_id,
+    created_at: overrides.created_at ?? new Date('2026-01-01'),
+  }
+}
+
+function snapshotWith(
+  pbis: BacklogPbi[],
+  storiesByPbi: Record<string, BacklogStory[]> = {},
+  tasksByStory: Record<string, BacklogTask[]> = {},
+  product?: { id: string; name: string },
+): ProductBacklogSnapshot {
+  return { product, pbis, storiesByPbi, tasksByStory }
+}
+
+// G7: mock fetch — never let it fall through to real network
+// G8: mockImplementation per call so each fetch gets a fresh Response
+function mockFetchSequence(
+  responses: Array<unknown | ((url: string, init?: RequestInit) => unknown)>,
+) {
+  let i = 0
+  return vi.spyOn(globalThis, 'fetch').mockImplementation((async (url: string, init?: RequestInit) => {
+    const r = responses[Math.min(i, responses.length - 1)]
+    i += 1
+    const body = typeof r === 'function' ? (r as (u: string, i?: RequestInit) => unknown)(url, init) : r
+    return new Response(JSON.stringify(body ?? null), { status: 200 })
+  }) as unknown as typeof fetch)
+}
+
+// ─────────────────────────────────────────────────────────────────────────
+// hydrateSnapshot
+// ─────────────────────────────────────────────────────────────────────────
+
+describe('hydrateSnapshot', () => {
+  it('vult entities en relations met gesorteerde id-lijsten', () => {
+    const pbiA = makePbi({ id: 'pbi-a', priority: 2, sort_order: 2 })
+    const pbiB = makePbi({ id: 'pbi-b', priority: 1, sort_order: 5 })
+    const pbiC = makePbi({ id: 'pbi-c', priority: 2, sort_order: 1 })
+    const storyB1 = makeStory({ id: 'st-1', pbi_id: 'pbi-b', sort_order: 2 })
+    const storyB2 = makeStory({ id: 'st-2', pbi_id: 'pbi-b', sort_order: 1 })
+    const taskA = makeTask({ id: 'tk-2', story_id: 'st-1', sort_order: 2 })
+    const taskB = makeTask({ id: 'tk-1', story_id: 'st-1', sort_order: 1 })
+
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith(
+        [pbiA, pbiB, pbiC],
+        { 'pbi-b': [storyB1, storyB2] },
+        { 'st-1': [taskA, taskB] },
+        { id: 'prod-1', name: 'Product 1' },
+      ),
+    )
+
+    const s = useProductWorkspaceStore.getState()
+    expect(s.entities.pbisById['pbi-a']).toBe(pbiA)
+    expect(s.entities.pbisById['pbi-b']).toBe(pbiB)
+    expect(s.entities.pbisById['pbi-c']).toBe(pbiC)
+    // pbi-b heeft priority 1 (komt eerst), dan pbi-c (sort_order 1) en pbi-a (sort_order 2)
+    expect(s.relations.pbiIds).toEqual(['pbi-b', 'pbi-c', 'pbi-a'])
+    expect(s.relations.storyIdsByPbi['pbi-b']).toEqual(['st-2', 'st-1'])
+    expect(s.relations.taskIdsByStory['st-1']).toEqual(['tk-1', 'tk-2'])
+    expect(s.context.activeProduct).toEqual({ id: 'prod-1', name: 'Product 1' })
+    expect(s.loading.loadedProductId).toBe('prod-1')
+  })
+
+  it('reset bestaande entities en relations bij her-hydratie', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'old-pbi' })]),
+    )
+    expect(useProductWorkspaceStore.getState().relations.pbiIds).toEqual(['old-pbi'])
+
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'new-pbi' })]),
+    )
+    const s = useProductWorkspaceStore.getState()
+    expect(s.entities.pbisById['old-pbi']).toBeUndefined()
+    expect(s.entities.pbisById['new-pbi']).toBeDefined()
+    expect(s.relations.pbiIds).toEqual(['new-pbi'])
+  })
+})
+
+// ─────────────────────────────────────────────────────────────────────────
+// Selection cascade
+// ─────────────────────────────────────────────────────────────────────────
+
+describe('selection cascade', () => {
+  it('setActivePbi reset story+task; setActiveStory reset task', () => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activePbiId = 'pbi-old'
+      s.context.activeStoryId = 'st-old'
+      s.context.activeTaskId = 'tk-old'
+    })
+
+    useProductWorkspaceStore.getState().setActivePbi('pbi-new')
+    let s = useProductWorkspaceStore.getState()
+    expect(s.context.activePbiId).toBe('pbi-new')
+    expect(s.context.activeStoryId).toBeNull()
+    expect(s.context.activeTaskId).toBeNull()
+
+    useProductWorkspaceStore.setState((draft) => {
+      draft.context.activeStoryId = 'st-old'
+      draft.context.activeTaskId = 'tk-old'
+    })
+    useProductWorkspaceStore.getState().setActiveStory('st-new')
+    s = useProductWorkspaceStore.getState()
+    expect(s.context.activeStoryId).toBe('st-new')
+    expect(s.context.activeTaskId).toBeNull()
+  })
+
+  it('setActiveProduct(null) ruimt entities en relations op', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith(
+        [makePbi({ id: 'p-1' })],
+        { 'p-1': [makeStory({ id: 's-1', pbi_id: 'p-1' })] },
+        { 's-1': [makeTask({ id: 't-1', story_id: 's-1' })] },
+        { id: 'prod-1', name: 'Product 1' },
+      ),
+    )
+
+    useProductWorkspaceStore.getState().setActiveProduct(null)
+    const s = useProductWorkspaceStore.getState()
+    expect(s.context.activeProduct).toBeNull()
+    expect(s.context.activePbiId).toBeNull()
+    expect(s.context.activeStoryId).toBeNull()
+    expect(s.context.activeTaskId).toBeNull()
+    expect(s.entities.pbisById).toEqual({})
+    expect(s.entities.storiesById).toEqual({})
+    expect(s.entities.tasksById).toEqual({})
+    expect(s.relations.pbiIds).toEqual([])
+    expect(s.relations.storyIdsByPbi).toEqual({})
+    expect(s.relations.taskIdsByStory).toEqual({})
+    expect(s.loading.loadedProductId).toBeNull()
+  })
+})
+
+// ─────────────────────────────────────────────────────────────────────────
+// applyRealtimeEvent
+// ─────────────────────────────────────────────────────────────────────────
+
+describe('applyRealtimeEvent — pbi', () => {
+  beforeEach(() => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'Product 1' }
+    })
+  })
+
+  it('I — voegt PBI toe en sorteert', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'a', priority: 2, sort_order: 5 })]),
+    )
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'I',
+      id: 'b',
+      product_id: 'prod-1',
+      code: 'B',
+      title: 'New PBI',
+      priority: 1,
+      sort_order: 1,
+      created_at: new Date('2026-02-01').toISOString(),
+      status: 'ready',
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.entities.pbisById['b']).toBeDefined()
+    expect(s.relations.pbiIds).toEqual(['b', 'a'])
+  })
+
+  it('I — idempotent voor bestaande id', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'a' })]),
+    )
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'I',
+      id: 'a',
+      product_id: 'prod-1',
+      title: 'mutated',
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.entities.pbisById['a'].title).toBe('PBI a') // niet overschreven
+    expect(s.relations.pbiIds).toEqual(['a'])
+  })
+
+  it('U — patch + her-sorteert', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([
+        makePbi({ id: 'a', priority: 2, sort_order: 1 }),
+        makePbi({ id: 'b', priority: 2, sort_order: 2 }),
+      ]),
+    )
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'U',
+      id: 'b',
+      product_id: 'prod-1',
+      priority: 1,
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.relations.pbiIds).toEqual(['b', 'a'])
+  })
+
+  it('D — verwijdert PBI inclusief child stories en tasks', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith(
+        [makePbi({ id: 'p1' })],
+        { p1: [makeStory({ id: 's1', pbi_id: 'p1' })] },
+        { s1: [makeTask({ id: 't1', story_id: 's1' })] },
+      ),
+    )
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'D',
+      id: 'p1',
+      product_id: 'prod-1',
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.entities.pbisById['p1']).toBeUndefined()
+    expect(s.entities.storiesById['s1']).toBeUndefined()
+    expect(s.entities.tasksById['t1']).toBeUndefined()
+    expect(s.relations.pbiIds).toEqual([])
+    expect(s.relations.storyIdsByPbi['p1']).toBeUndefined()
+    expect(s.relations.taskIdsByStory['s1']).toBeUndefined()
+  })
+
+  it('D — clear actieve PBI selectie als die onder de verwijderde PBI viel', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'p1' })]),
+    )
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activePbiId = 'p1'
+      s.context.activeStoryId = 's-x'
+      s.context.activeTaskId = 't-x'
+    })
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'D',
+      id: 'p1',
+      product_id: 'prod-1',
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.context.activePbiId).toBeNull()
+    expect(s.context.activeStoryId).toBeNull()
+    expect(s.context.activeTaskId).toBeNull()
+  })
+})
+
+describe('applyRealtimeEvent — story parent-move', () => {
+  beforeEach(() => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'Product 1' }
+    })
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith(
+        [makePbi({ id: 'p1' }), makePbi({ id: 'p2' })],
+        {
+          p1: [makeStory({ id: 's1', pbi_id: 'p1' })],
+          p2: [],
+        },
+      ),
+    )
+  })
+
+  it('U met andere pbi_id verplaatst story naar nieuwe parent-lijst', () => {
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'story',
+      op: 'U',
+      id: 's1',
+      product_id: 'prod-1',
+      pbi_id: 'p2',
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.relations.storyIdsByPbi['p1']).toEqual([])
+    expect(s.relations.storyIdsByPbi['p2']).toEqual(['s1'])
+    expect(s.entities.storiesById['s1'].pbi_id).toBe('p2')
+  })
+})
+
+describe('applyRealtimeEvent — task parent-move', () => {
+  beforeEach(() => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'Product 1' }
+    })
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith(
+        [makePbi({ id: 'p1' })],
+        { p1: [makeStory({ id: 's1', pbi_id: 'p1' }), makeStory({ id: 's2', pbi_id: 'p1' })] },
+        {
+          s1: [makeTask({ id: 't1', story_id: 's1' })],
+          s2: [],
+        },
+      ),
+    )
+  })
+
+  it('U met andere story_id verplaatst task naar nieuwe parent', () => {
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'task',
+      op: 'U',
+      id: 't1',
+      product_id: 'prod-1',
+      story_id: 's2',
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.relations.taskIdsByStory['s1']).toEqual([])
+    expect(s.relations.taskIdsByStory['s2']).toEqual(['t1'])
+    expect(s.entities.tasksById['t1'].story_id).toBe('s2')
+  })
+})
+
+describe('applyRealtimeEvent — andere product genegeerd', () => {
+  it('event met ander product_id raakt de store niet', () => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'Product 1' }
+    })
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'a' })]),
+    )
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'I',
+      id: 'b',
+      product_id: 'prod-2',
+      title: 'Other product',
+      priority: 1,
+      sort_order: 1,
+    })
+    const s = useProductWorkspaceStore.getState()
+    expect(s.entities.pbisById['b']).toBeUndefined()
+    expect(s.relations.pbiIds).toEqual(['a'])
+  })
+})
+
+describe('applyRealtimeEvent — unknown entity → resync trigger', () => {
+  function withSpy(): ReturnType<typeof vi.fn> {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'Product 1' }
+    })
+    const spy = vi.fn().mockResolvedValue(undefined)
+    useProductWorkspaceStore.setState((s) => {
+      s.resyncActiveScopes = spy as unknown as typeof s.resyncActiveScopes
+    })
+    return spy
+  }
+
+  it('unknown entity (b.v. comment) met matching product triggert resync', () => {
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'comment',
+      op: 'I',
+      id: 'cm-1',
+      product_id: 'prod-1',
+    } as unknown as Record<string, unknown>)
+    expect(spy).toHaveBeenCalledWith('unknown-event')
+  })
+
+  it('unknown entity met ander product_id triggert geen resync', () => {
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'comment',
+      op: 'I',
+      id: 'cm-1',
+      product_id: 'prod-2',
+    } as unknown as Record<string, unknown>)
+    expect(spy).not.toHaveBeenCalled()
+  })
+
+  it('claude_job_status (type-veld) triggert geen resync', () => {
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      type: 'claude_job_status',
+      job_id: 'job-1',
+      product_id: 'prod-1',
+      status: 'queued',
+    } as unknown as Record<string, unknown>)
+    expect(spy).not.toHaveBeenCalled()
+  })
+
+  it('worker_heartbeat (type-veld) triggert geen resync', () => {
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      type: 'worker_heartbeat',
+      worker_id: 'w-1',
+      product_id: 'prod-1',
+    } as unknown as Record<string, unknown>)
+    expect(spy).not.toHaveBeenCalled()
+  })
+
+  it('claude_job_enqueued (type-veld) triggert geen resync', () => {
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      type: 'claude_job_enqueued',
+      job_id: 'job-2',
+      product_id: 'prod-1',
+      kind: 'PER_TASK',
+    } as unknown as Record<string, unknown>)
+    expect(spy).not.toHaveBeenCalled()
+  })
+
+  it('payload zonder entity en zonder type wordt genegeerd', () => {
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      product_id: 'prod-1',
+      something: 'else',
+    } as unknown as Record<string, unknown>)
+    expect(spy).not.toHaveBeenCalled()
+  })
+
+  it('question-event met entity-veld maar zonder pbi/story/task triggert resync', () => {
+    // question is geen pbi/story/task entity dus telt als unknown wanneer
+    // hij geen 'type' draagt — dat zou een nieuwe entiteit kunnen zijn die
+    // we nog niet kennen.
+    const spy = withSpy()
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'question',
+      op: 'I',
+      id: 'q-1',
+      product_id: 'prod-1',
+    } as unknown as Record<string, unknown>)
+    expect(spy).toHaveBeenCalledWith('unknown-event')
+  })
+})
+
+// ─────────────────────────────────────────────────────────────────────────
+// ensure*Loaded fetches + race-safe guard + sortering
+// ─────────────────────────────────────────────────────────────────────────
+
+describe('ensureProductLoaded', () => {
+  it('fetcht backlog snapshot en hydreert met sortering', async () => {
+    const snapshot: ProductBacklogSnapshot = {
+      product: { id: 'prod-1', name: 'Product 1' },
+      pbis: [
+        makePbi({ id: 'a', priority: 2, sort_order: 5 }),
+        makePbi({ id: 'b', priority: 1, sort_order: 9 }),
+      ],
+      storiesByPbi: {},
+      tasksByStory: {},
+    }
+    const fetchSpy = mockFetchSequence([snapshot])
+
+    await useProductWorkspaceStore.getState().ensureProductLoaded('prod-1')
+
+    expect(fetchSpy).toHaveBeenCalledWith(
+      '/api/products/prod-1/backlog',
+      expect.objectContaining({ cache: 'no-store' }),
+    )
+    const s = useProductWorkspaceStore.getState()
+    expect(s.relations.pbiIds).toEqual(['b', 'a'])
+    expect(s.loading.loadedProductId).toBe('prod-1')
+    expect(s.loading.loadedPbiIds['a']).toBe(true)
+    expect(s.loading.loadedPbiIds['b']).toBe(true)
+  })
+})
+
+describe('race-safe ensure*Loaded — activeRequestId guard', () => {
+  it('oudere in-flight ensurePbiLoaded mag nieuwere selectie niet overschrijven', async () => {
+    let resolveOld: ((stories: BacklogStory[]) => void) | null = null
+
+    vi.spyOn(globalThis, 'fetch').mockImplementation((async (url: string) => {
+      if (url === '/api/pbis/pbi-old/stories') {
+        const stories = await new Promise<BacklogStory[]>((resolve) => {
+          resolveOld = resolve
+        })
+        return new Response(JSON.stringify(stories), { status: 200 })
+      }
+      if (url === '/api/pbis/pbi-new/stories') {
+        return new Response(
+          JSON.stringify([makeStory({ id: 'new-st', pbi_id: 'pbi-new' })]),
+          { status: 200 },
+        )
+      }
+      return new Response('null', { status: 200 })
+    }) as unknown as typeof fetch)
+
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'Product 1' }
+      s.context.activePbiId = 'pbi-old'
+      s.loading.activeRequestId = 'req-old'
+    })
+    const oldPromise = useProductWorkspaceStore
+      .getState()
+      .ensurePbiLoaded('pbi-old', 'req-old')
+
+    // gebruiker selecteert ondertussen pbi-new
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activePbiId = 'pbi-new'
+      s.loading.activeRequestId = 'req-new'
+    })
+    await useProductWorkspaceStore.getState().ensurePbiLoaded('pbi-new', 'req-new')
+
+    expect(useProductWorkspaceStore.getState().entities.storiesById['new-st']).toBeDefined()
+
+    // resolve de oude fetch — guard moet de stale data weigeren
+    resolveOld!([makeStory({ id: 'old-st', pbi_id: 'pbi-old' })])
+    await oldPromise
+
+    const s = useProductWorkspaceStore.getState()
+    expect(s.context.activePbiId).toBe('pbi-new')
+    expect(s.entities.storiesById['old-st']).toBeUndefined()
+    expect(s.entities.storiesById['new-st']).toBeDefined()
+  })
+})
+
+describe('ensureTaskLoaded — zet detail-flag', () => {
+  it('verrijkt task naar TaskDetail met _detail: true', async () => {
+    mockFetchSequence([
+      {
+        id: 't-1',
+        title: 'Task 1',
+        description: 'desc',
+        priority: 1,
+        sort_order: 1,
+        status: 'todo',
+        story_id: 's-1',
+        created_at: new Date('2026-02-01').toISOString(),
+        implementation_plan: 'detailed plan here',
+      },
+    ])
+
+    await useProductWorkspaceStore.getState().ensureTaskLoaded('t-1')
+    const task = useProductWorkspaceStore.getState().entities.tasksById['t-1'] as TaskDetail
+    expect(task._detail).toBe(true)
+    expect(task.implementation_plan).toBe('detailed plan here')
+    expect(useProductWorkspaceStore.getState().loading.loadedTaskIds['t-1']).toBe(true)
+  })
+})
+
+// ─────────────────────────────────────────────────────────────────────────
+// resyncActiveScopes
+// ─────────────────────────────────────────────────────────────────────────
+
+describe('resyncActiveScopes', () => {
+  it('triggert ensure-keten voor alle actieve scopes en zet sync velden', async () => {
+    const fetchSpy = mockFetchSequence([
+      // ensureProductLoaded
+      { product: { id: 'prod-1', name: 'P' }, pbis: [], storiesByPbi: {}, tasksByStory: {} },
+      // ensurePbiLoaded
+      [],
+      // ensureStoryLoaded
+      [],
+      // ensureTaskLoaded
+      {
+        id: 't-1',
+        title: 'T',
+        description: null,
+        priority: 1,
+        sort_order: 1,
+        status: 'todo',
+        story_id: 's-1',
+        created_at: '2026-02-01',
+      },
+    ])
+
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'P' }
+      s.context.activePbiId = 'pbi-1'
+      s.context.activeStoryId = 's-1'
+      s.context.activeTaskId = 't-1'
+    })
+
+    await useProductWorkspaceStore.getState().resyncActiveScopes('manual')
+
+    const calls = fetchSpy.mock.calls.map(([url]) => url)
+    expect(calls).toContain('/api/products/prod-1/backlog')
+    expect(calls).toContain('/api/pbis/pbi-1/stories')
+    expect(calls).toContain('/api/stories/s-1/tasks')
+    expect(calls).toContain('/api/tasks/t-1')
+
+    const s = useProductWorkspaceStore.getState()
+    expect(s.sync.lastResyncAt).toBeTypeOf('number')
+    expect(s.sync.resyncReason).toBe('manual')
+  })
+})
+
+// ─────────────────────────────────────────────────────────────────────────
+// Optimistic mutations
+// ─────────────────────────────────────────────────────────────────────────
+
+// ─────────────────────────────────────────────────────────────────────────
+// Restore-hint integratie (Story 4)
+// ─────────────────────────────────────────────────────────────────────────
+
+describe('restore-hint flow — setters persisteren hints', () => {
+  it('setActiveProduct schrijft lastActiveProductId', () => {
+    useProductWorkspaceStore.getState().setActiveProduct({ id: 'prod-1', name: 'P1' })
+    const raw = localStorage.getItem('product-workspace-hints')
+    expect(raw).not.toBeNull()
+    const hints = JSON.parse(raw!)
+    expect(hints.lastActiveProductId).toBe('prod-1')
+  })
+
+  it('setActivePbi schrijft lastActivePbiId per product', () => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'P1' }
+    })
+    useProductWorkspaceStore.getState().setActivePbi('pbi-a')
+    const hints = JSON.parse(localStorage.getItem('product-workspace-hints')!)
+    expect(hints.perProduct['prod-1'].lastActivePbiId).toBe('pbi-a')
+  })
+
+  it('setActiveStory schrijft lastActiveStoryId per product', () => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'P1' }
+    })
+    useProductWorkspaceStore.getState().setActiveStory('story-a')
+    const hints = JSON.parse(localStorage.getItem('product-workspace-hints')!)
+    expect(hints.perProduct['prod-1'].lastActiveStoryId).toBe('story-a')
+  })
+
+  it('setActiveTask schrijft lastActiveTaskId per product', () => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'P1' }
+    })
+    useProductWorkspaceStore.getState().setActiveTask('task-a')
+    const hints = JSON.parse(localStorage.getItem('product-workspace-hints')!)
+    expect(hints.perProduct['prod-1'].lastActiveTaskId).toBe('task-a')
+  })
+})
+
+describe('restore-hint flow — chain triggert na ensure*Loaded', () => {
+  it('hint die NIET in entities zit wordt genegeerd', async () => {
+    // Schrijf een hint voor een PBI die niet bestaat
+    localStorage.setItem(
+      'product-workspace-hints',
+      JSON.stringify({
+        lastActiveProductId: 'prod-1',
+        perProduct: { 'prod-1': { lastActivePbiId: 'ghost-pbi' } },
+      }),
+    )
+    // Mock ensureProductLoaded zodat hij een lege snapshot terugstuurt — geen
+    // ghost-pbi in entities.
+    mockFetchSequence([
+      { product: { id: 'prod-1', name: 'P1' }, pbis: [], storiesByPbi: {}, tasksByStory: {} },
+    ])
+
+    useProductWorkspaceStore.getState().setActiveProduct({ id: 'prod-1', name: 'P1' })
+    // Wacht tot async restore-flow afgewikkeld is.
+    await new Promise((r) => setTimeout(r, 20))
+
+    expect(useProductWorkspaceStore.getState().context.activePbiId).toBeNull()
+  })
+
+  it('hint die wel in entities zit wordt toegepast', async () => {
+    const validPbi = makePbi({ id: 'pbi-known' })
+    localStorage.setItem(
+      'product-workspace-hints',
+      JSON.stringify({
+        lastActiveProductId: 'prod-1',
+        perProduct: { 'prod-1': { lastActivePbiId: 'pbi-known' } },
+      }),
+    )
+    mockFetchSequence([
+      // ensureProductLoaded levert pbi-known
+      {
+        product: { id: 'prod-1', name: 'P1' },
+        pbis: [validPbi],
+        storiesByPbi: {},
+        tasksByStory: {},
+      },
+      // ensurePbiLoaded triggered door setActivePbi(hint) — geen stories
+      [],
+    ])
+
+    useProductWorkspaceStore.getState().setActiveProduct({ id: 'prod-1', name: 'P1' })
+    await new Promise((r) => setTimeout(r, 30))
+
+    expect(useProductWorkspaceStore.getState().context.activePbiId).toBe('pbi-known')
+  })
+})
+
+describe('optimistic mutations', () => {
+  it('rollback herstelt vorige pbi-order', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([
+        makePbi({ id: 'a', priority: 2, sort_order: 1 }),
+        makePbi({ id: 'b', priority: 2, sort_order: 2 }),
+      ]),
+    )
+    const prevOrder = [...useProductWorkspaceStore.getState().relations.pbiIds]
+
+    const id = useProductWorkspaceStore.getState().applyOptimisticMutation({
+      kind: 'pbi-order',
+      prevPbiIds: prevOrder,
+    })
+    // simuleer de optimistic order-wijziging buiten de mutation
+    useProductWorkspaceStore.setState((s) => {
+      s.relations.pbiIds = ['b', 'a']
+    })
+    expect(useProductWorkspaceStore.getState().relations.pbiIds).toEqual(['b', 'a'])
+
+    useProductWorkspaceStore.getState().rollbackMutation(id)
+    expect(useProductWorkspaceStore.getState().relations.pbiIds).toEqual(prevOrder)
+    expect(useProductWorkspaceStore.getState().pendingMutations[id]).toBeUndefined()
+  })
+
+  it('settle ruimt pending op zonder state te wijzigen', () => {
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'a' })]),
+    )
+    const id = useProductWorkspaceStore.getState().applyOptimisticMutation({
+      kind: 'pbi-order',
+      prevPbiIds: ['a'],
+    })
+    expect(useProductWorkspaceStore.getState().pendingMutations[id]).toBeDefined()
+
+    useProductWorkspaceStore.getState().settleMutation(id)
+    expect(useProductWorkspaceStore.getState().pendingMutations[id]).toBeUndefined()
+    expect(useProductWorkspaceStore.getState().relations.pbiIds).toEqual(['a'])
+  })
+
+  it('SSE-echo van een al-bestaande PBI is idempotent', () => {
+    useProductWorkspaceStore.setState((s) => {
+      s.context.activeProduct = { id: 'prod-1', name: 'P' }
+    })
+    useProductWorkspaceStore.getState().hydrateSnapshot(
+      snapshotWith([makePbi({ id: 'a', title: 'Origineel' })]),
+    )
+    useProductWorkspaceStore.getState().applyRealtimeEvent({
+      entity: 'pbi',
+      op: 'I',
+      id: 'a',
+      product_id: 'prod-1',
+      title: 'echo',
+    })
+    expect(useProductWorkspaceStore.getState().entities.pbisById['a'].title).toBe('Origineel')
+    expect(useProductWorkspaceStore.getState().relations.pbiIds).toEqual(['a'])
+  })
+})

app/(app)/products/[id]/page.tsx

@@ -11,6 +11,7 @@ import { StoryPanel } from '@/components/backlog/story-panel'
 import type { Story } from '@/components/backlog/story-panel'
 import { TaskPanel } from '@/components/backlog/task-panel'
 import { BacklogHydrationWrapper } from '@/components/backlog/backlog-hydration-wrapper'
+import { UrlTaskSync } from '@/components/backlog/url-task-sync'
 import { TaskDialog } from '@/app/_components/tasks/task-dialog'
 import { EditTaskLoader } from '@/app/_components/tasks/edit-task-loader'
 import { TaskDialogSkeleton } from '@/app/_components/tasks/task-dialog-skeleton'
@@ -59,6 +60,7 @@ export default async function ProductBacklogPage({ params, searchParams }: Props
         description: true,
         acceptance_criteria: true,
         priority: true,
+        sort_order: true,
         status: true,
         pbi_id: true,
         sprint_id: true,
@@ -81,7 +83,7 @@ export default async function ProductBacklogPage({ params, searchParams }: Props
     }),
   ])
 
-  // Group stories by PBI id
+  // Group stories by PBI id (status uit DB blijft UPPER_SNAKE in dit hydratie-pad)
   const storiesByPbi: Record<string, Story[]> = {}
   for (const story of stories) {
     if (!storiesByPbi[story.pbi_id]) storiesByPbi[story.pbi_id] = []
@@ -150,11 +152,12 @@ export default async function ProductBacklogPage({ params, searchParams }: Props
         <BacklogHydrationWrapper
           productId={id}
           initialData={{
-            pbis: pbis.map((p) => ({ id: p.id, code: p.code, title: p.title, priority: p.priority, description: p.description, created_at: p.created_at, status: pbiStatusToApi(p.status) })),
+            pbis: pbis.map((p) => ({ id: p.id, code: p.code, title: p.title, priority: p.priority, sort_order: p.sort_order, description: p.description, created_at: p.created_at, status: pbiStatusToApi(p.status) })),
             storiesByPbi,
             tasksByStory,
           }}
         >
+          <UrlTaskSync />
           <BacklogSplitPane
             cookieKey={`backlog-${id}`}
             defaultSplit={[20, 45, 35]}

app/(app)/products/[id]/sprint/[sprintId]/page.tsx

@@ -97,6 +97,7 @@ export default async function SprintBoardPage({ params, searchParams }: Props) {
     sprint_id: s.sprint_id,
     created_at: s.created_at,
     priority: s.priority,
+    sort_order: s.sort_order,
     status: s.status,
     taskCount: s.tasks.length,
     doneCount: s.tasks.filter(t => t.status === 'DONE').length,
@@ -148,6 +149,7 @@ export default async function SprintBoardPage({ params, searchParams }: Props) {
         sprint_id: s.sprint_id,
         created_at: s.created_at,
         priority: s.priority,
+        sort_order: s.sort_order,
         status: s.status,
         taskCount: 0,
         doneCount: 0,

app/(mobile)/m/products/[id]/page.tsx

@@ -15,6 +15,7 @@ import { StoryPanel } from '@/components/backlog/story-panel'
 import type { Story } from '@/components/backlog/story-panel'
 import { TaskPanel } from '@/components/backlog/task-panel'
 import { BacklogHydrationWrapper } from '@/components/backlog/backlog-hydration-wrapper'
+import { UrlTaskSync } from '@/components/backlog/url-task-sync'
 import { TaskDialog } from '@/app/_components/tasks/task-dialog'
 import { EditTaskLoader } from '@/app/_components/tasks/edit-task-loader'
 import { TaskDialogSkeleton } from '@/app/_components/tasks/task-dialog-skeleton'
@@ -49,6 +50,7 @@ export default async function MobileProductBacklogPage({ params, searchParams }:
         description: true,
         acceptance_criteria: true,
         priority: true,
+        sort_order: true,
         status: true,
         pbi_id: true,
         sprint_id: true,
@@ -90,11 +92,12 @@ export default async function MobileProductBacklogPage({ params, searchParams }:
       <BacklogHydrationWrapper
         productId={id}
         initialData={{
-          pbis: pbis.map((p) => ({ id: p.id, code: p.code, title: p.title, priority: p.priority, description: p.description, created_at: p.created_at, status: pbiStatusToApi(p.status) })),
+          pbis: pbis.map((p) => ({ id: p.id, code: p.code, title: p.title, priority: p.priority, sort_order: p.sort_order, description: p.description, created_at: p.created_at, status: pbiStatusToApi(p.status) })),
           storiesByPbi,
           tasksByStory,
         }}
       >
+        <UrlTaskSync />
         <BacklogSplitPane
           cookieKey={`backlog-${id}-mobile`}
           defaultSplit={[20, 45, 35]}

app/api/pbis/[id]/stories/route.ts

@@ -0,0 +1,52 @@
+// PBI-74 / T-870: GET /api/pbis/:id/stories
+//
+// Levert stories binnen een PBI voor ensurePbiLoaded. Access-control via
+// product-eigenaarschap van het bovenliggende PBI.
+import { authenticateApiRequest } from '@/lib/api-auth'
+import { prisma } from '@/lib/prisma'
+import { productAccessFilter } from '@/lib/product-access'
+import { storyStatusToApi } from '@/lib/task-status'
+
+export const dynamic = 'force-dynamic'
+
+export async function GET(
+  request: Request,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  const auth = await authenticateApiRequest(request)
+  if ('error' in auth) {
+    return Response.json({ error: auth.error }, { status: auth.status })
+  }
+
+  const { id } = await params
+
+  const pbi = await prisma.pbi.findFirst({
+    where: { id, product: productAccessFilter(auth.userId) },
+    select: { id: true },
+  })
+  if (!pbi) {
+    return Response.json({ error: 'PBI niet gevonden' }, { status: 404 })
+  }
+
+  const stories = await prisma.story.findMany({
+    where: { pbi_id: id },
+    orderBy: [{ priority: 'asc' }, { sort_order: 'asc' }, { created_at: 'asc' }],
+    select: {
+      id: true,
+      code: true,
+      title: true,
+      description: true,
+      acceptance_criteria: true,
+      priority: true,
+      sort_order: true,
+      status: true,
+      pbi_id: true,
+      sprint_id: true,
+      created_at: true,
+    },
+  })
+
+  return Response.json(
+    stories.map((s) => ({ ...s, status: storyStatusToApi(s.status) })),
+  )
+}

app/api/products/[id]/backlog/route.ts

@@ -0,0 +1,100 @@
+// PBI-74 / T-870: GET /api/products/:id/backlog
+//
+// Levert een volledige ProductBacklogSnapshot voor de workspace-store
+// (ensureProductLoaded). Auth + access-control consistent met andere
+// product-routes (authenticateApiRequest + productAccessFilter).
+import { authenticateApiRequest } from '@/lib/api-auth'
+import { prisma } from '@/lib/prisma'
+import { productAccessFilter } from '@/lib/product-access'
+import { pbiStatusToApi, storyStatusToApi, taskStatusToApi } from '@/lib/task-status'
+
+export const dynamic = 'force-dynamic'
+
+export async function GET(
+  request: Request,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  const auth = await authenticateApiRequest(request)
+  if ('error' in auth) {
+    return Response.json({ error: auth.error }, { status: auth.status })
+  }
+
+  const { id } = await params
+
+  const product = await prisma.product.findFirst({
+    where: { id, ...productAccessFilter(auth.userId) },
+    select: { id: true, name: true },
+  })
+  if (!product) {
+    return Response.json({ error: 'Product niet gevonden' }, { status: 404 })
+  }
+
+  const [pbis, stories, tasks] = await Promise.all([
+    prisma.pbi.findMany({
+      where: { product_id: id },
+      orderBy: [{ priority: 'asc' }, { sort_order: 'asc' }, { created_at: 'asc' }],
+      select: {
+        id: true,
+        code: true,
+        title: true,
+        priority: true,
+        sort_order: true,
+        description: true,
+        created_at: true,
+        status: true,
+      },
+    }),
+    prisma.story.findMany({
+      where: { product_id: id },
+      orderBy: [{ priority: 'asc' }, { sort_order: 'asc' }, { created_at: 'asc' }],
+      select: {
+        id: true,
+        code: true,
+        title: true,
+        description: true,
+        acceptance_criteria: true,
+        priority: true,
+        sort_order: true,
+        status: true,
+        pbi_id: true,
+        sprint_id: true,
+        created_at: true,
+      },
+    }),
+    prisma.task.findMany({
+      where: { story: { product_id: id } },
+      orderBy: [{ sort_order: 'asc' }, { created_at: 'asc' }],
+      select: {
+        id: true,
+        title: true,
+        description: true,
+        priority: true,
+        sort_order: true,
+        status: true,
+        story_id: true,
+        created_at: true,
+      },
+    }),
+  ])
+
+  const storiesByPbi: Record<string, unknown[]> = {}
+  for (const story of stories) {
+    const apiStory = { ...story, status: storyStatusToApi(story.status) }
+    if (!storiesByPbi[story.pbi_id]) storiesByPbi[story.pbi_id] = []
+    storiesByPbi[story.pbi_id].push(apiStory)
+  }
+
+  const tasksByStory: Record<string, unknown[]> = {}
+  for (const task of tasks) {
+    const apiTask = { ...task, status: taskStatusToApi(task.status) }
+    if (!tasksByStory[task.story_id]) tasksByStory[task.story_id] = []
+    tasksByStory[task.story_id].push(apiTask)
+  }
+
+  return Response.json({
+    product,
+    pbis: pbis.map((p) => ({ ...p, status: pbiStatusToApi(p.status) })),
+    storiesByPbi,
+    tasksByStory,
+  })
+}

app/api/stories/[id]/tasks/route.ts

@@ -0,0 +1,49 @@
+// PBI-74 / T-870: GET /api/stories/:id/tasks
+//
+// Levert tasks binnen een story voor ensureStoryLoaded. Access-control via
+// product-eigenaarschap van de bovenliggende story.
+import { authenticateApiRequest } from '@/lib/api-auth'
+import { prisma } from '@/lib/prisma'
+import { productAccessFilter } from '@/lib/product-access'
+import { taskStatusToApi } from '@/lib/task-status'
+
+export const dynamic = 'force-dynamic'
+
+export async function GET(
+  request: Request,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  const auth = await authenticateApiRequest(request)
+  if ('error' in auth) {
+    return Response.json({ error: auth.error }, { status: auth.status })
+  }
+
+  const { id } = await params
+
+  const story = await prisma.story.findFirst({
+    where: { id, product: productAccessFilter(auth.userId) },
+    select: { id: true },
+  })
+  if (!story) {
+    return Response.json({ error: 'Story niet gevonden' }, { status: 404 })
+  }
+
+  const tasks = await prisma.task.findMany({
+    where: { story_id: id },
+    orderBy: [{ sort_order: 'asc' }, { created_at: 'asc' }],
+    select: {
+      id: true,
+      title: true,
+      description: true,
+      priority: true,
+      sort_order: true,
+      status: true,
+      story_id: true,
+      created_at: true,
+    },
+  })
+
+  return Response.json(
+    tasks.map((t) => ({ ...t, status: taskStatusToApi(t.status) })),
+  )
+}

app/api/tasks/[id]/route.ts

@@ -3,6 +3,56 @@ import { prisma } from '@/lib/prisma'
 import { z } from 'zod'
 import { TASK_STATUS_API_VALUES, taskStatusFromApi, taskStatusToApi } from '@/lib/task-status'
 import { propagateStatusUpwards } from '@/lib/tasks-status-update'
+import { productAccessFilter } from '@/lib/product-access'
+
+// PBI-74 / T-869: force-dynamic zodat Next geen response-cache hangt aan
+// deze route — workspace-store leest hier verse data via ensureTaskLoaded.
+export const dynamic = 'force-dynamic'
+
+// PBI-74 / T-870: GET-handler voor ensureTaskLoaded. Levert TaskDetail-shape
+// (extends BacklogTask met implementation_plan etc.). Access-control via
+// product van de parent-story.
+export async function GET(
+  request: Request,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  const auth = await authenticateApiRequest(request)
+  if ('error' in auth) {
+    return Response.json({ error: auth.error }, { status: auth.status })
+  }
+
+  const { id } = await params
+
+  const task = await prisma.task.findFirst({
+    where: {
+      id,
+      story: { product: productAccessFilter(auth.userId) },
+    },
+    select: {
+      id: true,
+      title: true,
+      description: true,
+      priority: true,
+      sort_order: true,
+      status: true,
+      story_id: true,
+      created_at: true,
+      implementation_plan: true,
+      requires_opus: true,
+      verify_only: true,
+      verify_required: true,
+    },
+  })
+  if (!task) {
+    return Response.json({ error: 'Task niet gevonden' }, { status: 404 })
+  }
+
+  return Response.json({
+    ...task,
+    status: taskStatusToApi(task.status),
+    _detail: true,
+  })
+}
 
 // `review` is a valid TaskStatus in the DB and the kanban-board UI, but the
 // sprint task list (components/sprint/task-list.tsx) does not yet render it.

components/backlog/backlog-hydration-wrapper.tsx

@@ -1,8 +1,15 @@
 'use client'
 
 import { useEffect, useRef } from 'react'
-import { useBacklogStore, type BacklogPbi, type BacklogStory, type BacklogTask } from '@/stores/backlog-store'
 import { useBacklogRealtime } from '@/lib/realtime/use-backlog-realtime'
+import { useWorkspaceResync } from '@/lib/realtime/use-workspace-resync'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+import type {
+  BacklogPbi,
+  BacklogStory,
+  BacklogTask,
+  ProductBacklogSnapshot,
+} from '@/stores/product-workspace/types'
 
 interface InitialData {
   pbis: BacklogPbi[]
@@ -13,6 +20,7 @@ interface InitialData {
 interface BacklogHydrationWrapperProps {
   initialData: InitialData
   productId: string
+  productName?: string
   children: React.ReactNode
 }
 
@@ -27,19 +35,40 @@ function fingerprint(data: InitialData): string {
   return `${pbiPart}|${storyPart}|${taskPart}`
 }
 
-export function BacklogHydrationWrapper({ initialData, productId, children }: BacklogHydrationWrapperProps) {
+// PBI-74 / Story 8: workspace-store is nu enige bron — dual-dispatch weg.
-  const setInitialData = useBacklogStore((s) => s.setInitialData)
+function toWorkspaceSnapshot(
+  data: InitialData,
+  productId: string,
+  productName: string | undefined,
+): ProductBacklogSnapshot {
+  return {
+    product: { id: productId, name: productName ?? '' },
+    pbis: data.pbis,
+    storiesByPbi: data.storiesByPbi,
+    tasksByStory: data.tasksByStory,
+  }
+}
+
+export function BacklogHydrationWrapper({
+  initialData,
+  productId,
+  productName,
+  children,
+}: BacklogHydrationWrapperProps) {
   const lastFingerprint = useRef<string>('')
 
   useEffect(() => {
     const fp = fingerprint(initialData)
     if (fp !== lastFingerprint.current) {
       lastFingerprint.current = fp
-      setInitialData(initialData)
+      useProductWorkspaceStore
+        .getState()
+        .hydrateSnapshot(toWorkspaceSnapshot(initialData, productId, productName))
     }
-  }, [initialData, setInitialData])
+  }, [initialData, productId, productName])
 
   useBacklogRealtime(productId)
+  useWorkspaceResync()
 
   return <>{children}</>
 }

components/backlog/backlog-split-pane.tsx

@@ -1,13 +1,16 @@
 'use client'
 
 import { useState } from 'react'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
 import { SplitPane, type SplitPaneProps } from '@/components/split-pane/split-pane'
 
 type Props = Omit<SplitPaneProps, 'activeTab' | 'onActiveTabChange'>
 
+// PBI-74 / T-848: leest active PBI/story-ids uit workspace-store. Primitives,
+// dus geen useShallow nodig.
 export function BacklogSplitPane(props: Props) {
-  const { selectedPbiId, selectedStoryId } = useSelectionStore()
+  const selectedPbiId = useProductWorkspaceStore((s) => s.context.activePbiId)
+  const selectedStoryId = useProductWorkspaceStore((s) => s.context.activeStoryId)
   const [activeTab, setActiveTab] = useState(0)
 
   // React-recommended "derived state from props" pattern: update state during render

components/backlog/pbi-list.tsx

@@ -25,9 +25,10 @@ import { CheckSquare, Square } from 'lucide-react'
 import { Button } from '@/components/ui/button'
 import { Badge } from '@/components/ui/badge'
 import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useShallow } from 'zustand/react/shallow'
-import { usePlannerStore } from '@/stores/planner-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
-import { useBacklogStore } from '@/stores/backlog-store'
+import { selectVisiblePbis } from '@/stores/product-workspace/selectors'
+import type { BacklogPbi as WorkspacePbi } from '@/stores/product-workspace/types'
 import { deletePbiAction } from '@/actions/pbis'
 import { reorderPbisAction, updatePbiPriorityAction } from '@/actions/stories'
 import { cn } from '@/lib/utils'
@@ -235,10 +236,13 @@ function SortablePbiRow({
 }
 
 // --- Main component ---
+// PBI-74 / T-849: leest pbis + actieve selectie uit workspace-store via
+// useShallow-selector. DnD-mutaties via applyOptimisticMutation/rollback/settle.
 export function PbiList({ productId, isDemo }: PbiListProps) {
-  const pbis = useBacklogStore((s) => s.pbis)
+  // selectVisiblePbis is gesorteerd op priority/sort_order; useShallow
-  const { selectedPbiId, selectPbi } = useSelectionStore()
+  // voorkomt re-render op ongerelateerde store-mutaties (G2).
-  const { pbiOrder, pbiPriority, initPbis, reorderPbis, rollbackPbis, updatePbiPriority } = usePlannerStore()
+  const pbis = useProductWorkspaceStore(useShallow(selectVisiblePbis)) as WorkspacePbi[]
+  const selectedPbiId = useProductWorkspaceStore((s) => s.context.activePbiId)
   // Defaults match SSR; persisted values applied post-mount in the loader effect below.
   // This avoids hydration mismatch when localStorage holds non-default values.
   const [filterPriority, setFilterPriority] = useState<number | 'all'>('all')
@@ -295,22 +299,10 @@ export function PbiList({ productId, isDemo }: PbiListProps) {
   useEffect(() => { if (prefsLoaded) localStorage.setItem('scrum4me:pbi_filter_status', filterStatus) }, [filterStatus, prefsLoaded])
   useEffect(() => { if (prefsLoaded) localStorage.setItem('scrum4me:pbi_sort_dir', sortDir) }, [sortDir, prefsLoaded])
 
-  // Sync server data into store — use stable string dep to avoid infinite loop
+  // pbis komen al gesorteerd binnen via selectVisiblePbis (priority + sort_order).
-  const pbiIdKey = pbis.map(p => p.id).join(',')
+  // Geen aparte order/priority maps meer — workspace-store entities zijn de waarheid.
-  useEffect(() => {
-    initPbis(productId, pbiIdKey ? pbiIdKey.split(',') : [])
-    // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [productId, pbiIdKey])
-
-  // Build ordered PBI list from store (or fall back to server order)
-  const order = pbiOrder[productId] ?? pbis.map(p => p.id)
   const pbiMap = Object.fromEntries(pbis.map(p => [p.id, p]))
-
+  const orderedPbis = pbis
-  // Apply priority overrides from store
-  const orderedPbis = order
-    .map(id => pbiMap[id])
-    .filter(Boolean)
-    .map(p => ({ ...p, priority: pbiPriority[p.id] ?? p.priority }))
 
   const base = orderedPbis.filter(p => {
     if (filterPriority !== 'all' && p.priority !== filterPriority) return false
@@ -353,30 +345,58 @@ export function PbiList({ productId, isDemo }: PbiListProps) {
     const overPbi = pbiMap[over.id as string]
     if (!activePbi || !overPbi) return
 
-    const prevOrder = [...order]
+    const store = useProductWorkspaceStore.getState()
-    const oldIndex = order.indexOf(active.id as string)
+    const prevOrder = [...store.relations.pbiIds]
-    const newIndex = order.indexOf(over.id as string)
+    const oldIndex = prevOrder.indexOf(active.id as string)
-    const newOrder = arrayMove([...order], oldIndex, newIndex)
+    const newIndex = prevOrder.indexOf(over.id as string)
+    if (oldIndex === -1 || newIndex === -1) return
+    const newOrder = arrayMove([...prevOrder], oldIndex, newIndex)
 
-    // Optimistic update
+    // Snapshot rollback-info en pas optimistisch toe.
-    reorderPbis(productId, newOrder)
+    const orderMutationId = store.applyOptimisticMutation({
+      kind: 'pbi-order',
+      prevPbiIds: prevOrder,
+    })
+    useProductWorkspaceStore.setState((s) => {
+      s.relations.pbiIds = newOrder
+    })
 
     const priorityChanged = activePbi.priority !== overPbi.priority
+    let priorityMutationId: string | null = null
+    if (priorityChanged) {
+      priorityMutationId = store.applyOptimisticMutation({
+        kind: 'entity-patch',
+        entity: 'pbi',
+        id: active.id as string,
+        prev: store.entities.pbisById[active.id as string],
+      })
+      useProductWorkspaceStore.setState((s) => {
+        const pbi = s.entities.pbisById[active.id as string]
+        if (pbi) pbi.priority = overPbi.priority
+      })
+    }
 
     startTransition(async () => {
+      const settle = () => {
+        const st = useProductWorkspaceStore.getState()
+        if (priorityMutationId) st.settleMutation(priorityMutationId)
+        st.settleMutation(orderMutationId)
+      }
+      const rollback = (msg: string) => {
+        const st = useProductWorkspaceStore.getState()
+        if (priorityMutationId) st.rollbackMutation(priorityMutationId)
+        st.rollbackMutation(orderMutationId)
+        toast.error(msg)
+      }
+
       if (priorityChanged) {
-        updatePbiPriority(active.id as string, overPbi.priority)
         const result = await updatePbiPriorityAction(active.id as string, overPbi.priority, productId)
-        if (!result.success) {
+        if (result.success) settle()
-          rollbackPbis(productId, prevOrder)
+        else rollback('Prioriteit opslaan mislukt')
-          toast.error('Prioriteit opslaan mislukt')
-        }
       } else {
         const result = await reorderPbisAction(productId, newOrder)
-        if (!result.success) {
+        if (result.success) settle()
-          rollbackPbis(productId, prevOrder)
+        else rollback('Volgorde opslaan mislukt')
-          toast.error('Volgorde opslaan mislukt')
-        }
       }
     })
   }
@@ -384,7 +404,9 @@ export function PbiList({ productId, isDemo }: PbiListProps) {
   function handleDelete(id: string) {
     startTransition(async () => {
       await deletePbiAction(id)
-      if (selectedPbiId === id) selectPbi(null)
+      if (selectedPbiId === id) {
+        useProductWorkspaceStore.getState().setActivePbi(null)
+      }
     })
   }
 
@@ -561,7 +583,7 @@ export function PbiList({ productId, isDemo }: PbiListProps) {
                     isDemo={isDemo}
                     selectionMode={selectionMode}
                     isChecked={selectedIds.has(pbi.id)}
-                    onSelect={() => selectPbi(pbi.id)}
+                    onSelect={() => useProductWorkspaceStore.getState().setActivePbi(pbi.id)}
                     onToggleCheck={() => toggleCheck(pbi.id)}
                     onEdit={() => setDialogState({ mode: 'edit', productId, pbi })}
                     onDelete={() => handleDelete(pbi.id)}

components/backlog/story-panel.tsx

@@ -25,9 +25,10 @@ import { Button } from '@/components/ui/button'
 import { Badge } from '@/components/ui/badge'
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select'
 import { PanelNavBar } from '@/components/shared/panel-nav-bar'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useShallow } from 'zustand/react/shallow'
-import { usePlannerStore } from '@/stores/planner-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
-import { useBacklogStore } from '@/stores/backlog-store'
+import { selectStoriesForActivePbi } from '@/stores/product-workspace/selectors'
+import type { BacklogStory as WorkspaceStory } from '@/stores/product-workspace/types'
 import { reorderStoriesAction } from '@/actions/stories'
 import { StoryDialog, type StoryDialogState } from './story-dialog'
 import { debugProps } from '@/lib/debug'
@@ -55,6 +56,7 @@ export interface Story {
   description: string | null
   acceptance_criteria: string | null
   priority: number
+  sort_order: number
   status: string
   pbi_id: string
   sprint_id: string | null
@@ -122,10 +124,12 @@ function SortableStoryBlock({
 }
 
 // --- Main component ---
+// PBI-74 / T-850: leest stories voor active PBI via selectStoriesForActivePbi
+// (useShallow). DnD via applyOptimisticMutation('story-order').
 export function StoryPanel({ productId, isDemo }: StoryPanelProps) {
-  const { selectedPbiId, selectedStoryId, selectStory } = useSelectionStore()
+  const selectedPbiId = useProductWorkspaceStore((s) => s.context.activePbiId)
-  const storiesByPbi = useBacklogStore((s) => s.storiesByPbi)
+  const selectedStoryId = useProductWorkspaceStore((s) => s.context.activeStoryId)
-  const { storyOrder, initStories, reorderStories, rollbackStories } = usePlannerStore()
+  const rawStories = useProductWorkspaceStore(useShallow(selectStoriesForActivePbi)) as WorkspaceStory[]
   const [filterStatus, setFilterStatus] = useState<string | null>(null)
   const [filterPriority, setFilterPriority] = useState<number | null>(null)
   const [sortMode, setSortMode] = useState<SortMode>(() => {
@@ -138,20 +142,9 @@ export function StoryPanel({ productId, isDemo }: StoryPanelProps) {
 
   useEffect(() => { localStorage.setItem('scrum4me:story_sort', sortMode) }, [sortMode])
 
-  const rawStories = selectedPbiId ? (storiesByPbi[selectedPbiId] ?? []) : []
+  // rawStories komt al gesorteerd binnen via selectStoriesForActivePbi.
-
-  // Sync into store — use stable string dep to avoid infinite loop
-  const storyIdKey = rawStories.map(s => s.id).join(',')
-  useEffect(() => {
-    if (selectedPbiId) {
-      initStories(selectedPbiId, storyIdKey ? storyIdKey.split(',') : [])
-    }
-    // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [selectedPbiId, storyIdKey])
-
   const storyMap = Object.fromEntries(rawStories.map(s => [s.id, s]))
-  const order = (selectedPbiId ? storyOrder[selectedPbiId] : null) ?? rawStories.map(s => s.id)
+  const orderedStories = rawStories
-  const orderedStories = order.map(id => storyMap[id]).filter(Boolean)
 
   const base = orderedStories
     .filter(s => !filterStatus || s.status === filterStatus)
@@ -185,14 +178,36 @@ export function StoryPanel({ productId, isDemo }: StoryPanelProps) {
     const overStory = storyMap[over.id as string]
     if (!activeStory || !overStory) return
 
-    const prevOrder = [...order]
+    const store = useProductWorkspaceStore.getState()
-    const oldIndex = order.indexOf(active.id as string)
+    const prevOrder = [...(store.relations.storyIdsByPbi[selectedPbiId] ?? [])]
-    const newIndex = order.indexOf(over.id as string)
+    const oldIndex = prevOrder.indexOf(active.id as string)
-    const newOrder = arrayMove([...order], oldIndex, newIndex)
+    const newIndex = prevOrder.indexOf(over.id as string)
+    if (oldIndex === -1 || newIndex === -1) return
+    const newOrder = arrayMove([...prevOrder], oldIndex, newIndex)
 
-    reorderStories(selectedPbiId, newOrder)
+    const orderMutationId = store.applyOptimisticMutation({
+      kind: 'story-order',
+      pbiId: selectedPbiId,
+      prevStoryIds: prevOrder,
+    })
+    useProductWorkspaceStore.setState((s) => {
+      s.relations.storyIdsByPbi[selectedPbiId] = newOrder
+    })
 
     const priorityChanged = activeStory.priority !== overStory.priority
+    let priorityMutationId: string | null = null
+    if (priorityChanged) {
+      priorityMutationId = store.applyOptimisticMutation({
+        kind: 'entity-patch',
+        entity: 'story',
+        id: active.id as string,
+        prev: store.entities.storiesById[active.id as string],
+      })
+      useProductWorkspaceStore.setState((s) => {
+        const story = s.entities.storiesById[active.id as string]
+        if (story) story.priority = overStory.priority
+      })
+    }
 
     startTransition(async () => {
       const result = await reorderStoriesAction(
@@ -201,8 +216,13 @@ export function StoryPanel({ productId, isDemo }: StoryPanelProps) {
         newOrder,
         priorityChanged ? overStory.priority : undefined
       )
-      if (!result.success) {
+      const st = useProductWorkspaceStore.getState()
-        rollbackStories(selectedPbiId, prevOrder)
+      if (result.success) {
+        if (priorityMutationId) st.settleMutation(priorityMutationId)
+        st.settleMutation(orderMutationId)
+      } else {
+        if (priorityMutationId) st.rollbackMutation(priorityMutationId)
+        st.rollbackMutation(orderMutationId)
         toast.error('Volgorde opslaan mislukt')
       }
     })
@@ -284,7 +304,7 @@ export function StoryPanel({ productId, isDemo }: StoryPanelProps) {
                     key={story.id}
                     story={story}
                     isSelected={selectedStoryId === story.id}
-                    onSelect={() => selectStory(story.id)}
+                    onSelect={() => useProductWorkspaceStore.getState().setActiveStory(story.id)}
                     onEdit={() => setStoryDialogState({ mode: 'edit', story, productId })}
                   />
                 ))}

components/backlog/task-panel.tsx

@@ -26,8 +26,13 @@ import { Badge } from '@/components/ui/badge'
 import { Button } from '@/components/ui/button'
 import { PanelNavBar } from '@/components/shared/panel-nav-bar'
 import { DemoTooltip } from '@/components/shared/demo-tooltip'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useShallow } from 'zustand/react/shallow'
-import { useBacklogStore, type BacklogTask } from '@/stores/backlog-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+import { selectTasksForActiveStory } from '@/stores/product-workspace/selectors'
+import type {
+  BacklogTask,
+  TaskDetail,
+} from '@/stores/product-workspace/types'
 import { reorderTasksAction } from '@/actions/tasks'
 import { BacklogCard } from './backlog-card'
 import { debugProps } from '@/lib/debug'
@@ -52,7 +57,7 @@ function SortableTaskCard({
   isDemo,
   onClick,
 }: {
-  task: BacklogTask
+  task: BacklogTask | TaskDetail
   isDemo: boolean
   onClick: () => void
 }) {
@@ -94,22 +99,20 @@ interface TaskPanelProps {
   closePath: string
 }
 
+// PBI-74 / T-851: leest tasks voor active story via selectTasksForActiveStory
+// (useShallow). DnD via applyOptimisticMutation('task-order'). Detail-view
+// (ensureTaskLoaded + isDetail()) zit in de task-dialog, niet in deze lijst.
 export function TaskPanel({ isDemo, closePath }: TaskPanelProps) {
   const router = useRouter()
   const [, startTransition] = useTransition()
-  const selectedStoryId = useSelectionStore((s) => s.selectedStoryId)
+  const selectedStoryId = useProductWorkspaceStore((s) => s.context.activeStoryId)
-  const tasksByStory = useBacklogStore((s) => s.tasksByStory)
+  const rawTasks = useProductWorkspaceStore(useShallow(selectTasksForActiveStory)) as
+    | (BacklogTask | TaskDetail)[]
   const [activeDragId, setActiveDragId] = useState<string | null>(null)
-  const [localOrder, setLocalOrder] = useState<string[] | null>(null)
 
-  const rawTasks = selectedStoryId ? (tasksByStory[selectedStoryId] ?? []) : null
+  const tasks: (BacklogTask | TaskDetail)[] | null = selectedStoryId
-
+    ? rawTasks
-  // Merge local order with rawTasks for optimistic reorder
+    : null
-  const tasks: BacklogTask[] | null = rawTasks === null
-    ? null
-    : localOrder
-      ? localOrder.map((id) => rawTasks.find((t) => t.id === id)).filter(Boolean) as BacklogTask[]
-      : rawTasks
 
   const sensors = useSensors(
     useSensor(PointerSensor, { activationConstraint: { distance: 5 } }),
@@ -126,19 +129,30 @@ export function TaskPanel({ isDemo, closePath }: TaskPanelProps) {
     const { active, over } = event
     if (!over || active.id === over.id) return
 
-    const ids = tasks.map((t) => t.id)
+    const store = useProductWorkspaceStore.getState()
-    const oldIndex = ids.indexOf(active.id as string)
+    const prevOrder = [...(store.relations.taskIdsByStory[selectedStoryId] ?? [])]
-    const newIndex = ids.indexOf(over.id as string)
+    const oldIndex = prevOrder.indexOf(active.id as string)
+    const newIndex = prevOrder.indexOf(over.id as string)
     if (oldIndex === -1 || newIndex === -1) return
+    const newOrder = arrayMove([...prevOrder], oldIndex, newIndex)
 
-    const newOrder = arrayMove(ids, oldIndex, newIndex)
+    const orderMutationId = store.applyOptimisticMutation({
-    setLocalOrder(newOrder)
+      kind: 'task-order',
+      storyId: selectedStoryId,
+      prevTaskIds: prevOrder,
+    })
+    useProductWorkspaceStore.setState((s) => {
+      s.relations.taskIdsByStory[selectedStoryId] = newOrder
+    })
 
     startTransition(async () => {
       const result = await reorderTasksAction(selectedStoryId, newOrder)
+      const st = useProductWorkspaceStore.getState()
       if (result?.error) {
-        setLocalOrder(null)
+        st.rollbackMutation(orderMutationId)
         toast.error(result.error)
+      } else {
+        st.settleMutation(orderMutationId)
       }
     })
   }

components/backlog/url-task-sync.tsx

@@ -0,0 +1,32 @@
+'use client'
+
+// PBI-74 / T-859: URL-prioriteit boven restore-hint.
+//
+// Als de route `?editTask=<id>` draagt, wint dat boven de localStorage-hint
+// die de restore-flow normaal zou toepassen. We schrijven de URL-id direct
+// naar de task-hint en roepen setActiveTask aan; de restore-flow leest de
+// task-hint pas na drie ensure*Loaded-awaits, dus onze schrijfactie wint
+// in de praktijk altijd.
+
+import { useEffect } from 'react'
+import { useSearchParams } from 'next/navigation'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+import { writeTaskHint } from '@/stores/product-workspace/restore'
+
+export function UrlTaskSync() {
+  const searchParams = useSearchParams()
+  const editTask = searchParams.get('editTask')
+
+  useEffect(() => {
+    if (!editTask) return
+    const productId = useProductWorkspaceStore.getState().context.activeProduct?.id
+    if (productId) {
+      // Hint overschrijven zodat restore-flow's setActiveTask op deze id eindigt
+      // (mocht hij na onze directe call komen).
+      writeTaskHint(productId, editTask)
+    }
+    useProductWorkspaceStore.getState().setActiveTask(editTask)
+  }, [editTask])
+
+  return null
+}

components/shared/set-current-product.tsx

@@ -1,16 +1,18 @@
 'use client'
 
 import { useEffect } from 'react'
-import { useProductStore } from '@/stores/product-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
 import { debugProps } from '@/lib/debug'
 
+// PBI-74 / T-853: workspace-store is nu enige bron voor active product.
+// De voorganger (stores/product-store.ts) wordt in Story 8 (T-876) verwijderd.
 export function SetCurrentProduct({ id, name }: { id: string; name: string }) {
-  const { setCurrentProduct, clearCurrentProduct } = useProductStore()
-
   useEffect(() => {
-    setCurrentProduct(id, name)
+    useProductWorkspaceStore.getState().setActiveProduct({ id, name })
-    return () => clearCurrentProduct()
+    return () => {
-  }, [id, name, setCurrentProduct, clearCurrentProduct])
+      useProductWorkspaceStore.getState().setActiveProduct(null)
+    }
+  }, [id, name])
 
   return <span {...debugProps('set-current-product')} hidden />
 }

components/sprint/sprint-backlog.tsx

@@ -45,6 +45,7 @@ export interface SprintStory {
   sprint_id: string | null
   created_at: Date
   priority: number
+  sort_order: number
   status: string
   taskCount: number
   doneCount: number

components/sprint/start-sprint-button.tsx

@@ -21,8 +21,12 @@ import {
   entityDialogHeaderClasses,
 } from '@/components/shared/entity-dialog-layout'
 import { createSprintAction } from '@/actions/sprints'
-import { useSelectionStore } from '@/stores/selection-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
-import { useBacklogStore } from '@/stores/backlog-store'
+import {
+  selectActivePbi,
+  selectStoriesForActivePbi,
+} from '@/stores/product-workspace/selectors'
+import { useShallow } from 'zustand/react/shallow'
 
 interface StartSprintButtonProps {
   productId: string
@@ -46,14 +50,11 @@ export function StartSprintButton({ productId, isDemo = false }: StartSprintButt
   const [dirty, setDirty] = useState(false)
   const formRef = useRef<HTMLFormElement>(null)
   const router = useRouter()
-  const selectedPbiId = useSelectionStore((s) => s.selectedPbiId)
+  // PBI-74 / T-852: actief PBI + free-story count via workspace-store selectors.
-  const selectedPbi = useBacklogStore((s) =>
+  const selectedPbiId = useProductWorkspaceStore((s) => s.context.activePbiId)
-    selectedPbiId ? s.pbis.find((p) => p.id === selectedPbiId) ?? null : null,
+  const selectedPbi = useProductWorkspaceStore(selectActivePbi)
-  )
+  const stories = useProductWorkspaceStore(useShallow(selectStoriesForActivePbi))
-  const freeStoryCount = useBacklogStore((s) => {
+  const freeStoryCount = stories.filter((story) => story.sprint_id === null).length
-    if (!selectedPbiId) return 0
-    return (s.storiesByPbi[selectedPbiId] ?? []).filter((story) => story.sprint_id === null).length
-  })
 
   const [state, formAction, pending] = useActionState<ActionResult | undefined, FormData>(
     async (_prev, fd) => {

docs/INDEX.md

@@ -2,7 +2,7 @@
 
 # Documentation Index
 
-Auto-generated on 2026-05-09 from front-matter and headings.
+Auto-generated on 2026-05-10 from front-matter and headings.
 
 ## Architecture Decision Records
 
@@ -62,6 +62,7 @@ Auto-generated on 2026-05-09 from front-matter and headings.
 | [Tweede Claude Agent — Planning Agent](./plans/tweede-claude-agent-planning.md) | proposal | 2026-05-03 |
 | [Scrum4Me — v1.0 readiness](./plans/v1-readiness.md) | active | 2026-05-04 |
 | [Zustand store rearchitecture - active context, realtime en resync](./plans/zustand-store-rearchitecture.md) | ready-to-execute | 2026-05-09 |
+| [Zustand workspace-store implementatieplan (PBI-74)](./plans/zustand-workspace-store-implementation.md) | ready-to-execute | 2026-05-09 |
 
 ### Archive
 
@@ -89,7 +90,8 @@ Auto-generated on 2026-05-09 from front-matter and headings.
 | [Float sort_order (drag-and-drop volgorde)](./patterns/sort-order.md) | active | 2026-05-03 |
 | [Story met UI-component](./patterns/story-with-ui-component.md) | active | 2026-05-03 |
 | [Web Push](./patterns/web-push.md) | active | 2026-05-07 |
-| [Zustand optimistische update + rollback](./patterns/zustand-optimistic.md) | active | 2026-05-03 |
+| [Workspace-store + realtime — bounded-context patroon](./patterns/workspace-store.md) | active | 2026-05-10 |
+| [Zustand optimistische update + rollback](./patterns/zustand-optimistic.md) | active | 2026-05-10 |
 
 ## Other Docs
 

docs/api/rest-contract.md

@@ -527,6 +527,38 @@ curl -X POST -H "Authorization: Bearer $CRON_SECRET" \
 
 ---
 
+## Workspace store endpoint audit (PBI-74)
+
+`product-workspace-store` heeft vier `ensure*Loaded`-loaders. Deze tabel
+documenteert welke routes al bestaan en welke in Story 7 (T-870) toegevoegd
+worden. Tot dan retourneert de stub-default in vitest een lege response.
+
+| Loader | URL | Status | Op te leveren in |
+|---|---|---|---|
+| `ensureProductLoaded(productId)` | `GET /api/products/:id/backlog` | **ontbreekt** | T-870 (Story 7) |
+| `ensurePbiLoaded(pbiId)` | `GET /api/pbis/:id/stories` | **ontbreekt** (en `/api/pbis` route-folder bestaat nog niet) | T-870 (Story 7) |
+| `ensureStoryLoaded(storyId)` | `GET /api/stories/:id/tasks` | **ontbreekt** (alleen `tasks/reorder` bestaat) | T-870 (Story 7) |
+| `ensureTaskLoaded(taskId)` | `GET /api/tasks/:id` | **ontbreekt** (alleen `PATCH` bestaat) | T-870 (Story 7) |
+
+Vereisten voor de toe te voegen routes:
+
+- Auth via `authenticateApiRequest` (Bearer-token), conform bestaande patroon.
+- Access-control via `getAccessibleProduct(productId, userId)` uit
+  `lib/product-access.ts` waar de route product-context heeft.
+- `export const dynamic = 'force-dynamic'` zodat Next geen response-cache
+  introduceert (T-869 in Story 7).
+- Response-shape:
+  - `GET /api/products/:id/backlog` → `ProductBacklogSnapshot` (`{ product?, pbis[], storiesByPbi, tasksByStory }`).
+  - `GET /api/pbis/:id/stories` → `BacklogStory[]`.
+  - `GET /api/stories/:id/tasks` → `BacklogTask[]`.
+  - `GET /api/tasks/:id` → `TaskDetail` (extends `BacklogTask` met `_detail: true` plus extra velden zoals `implementation_plan`, `acceptance_criteria`, `requires_opus`, `estimated_minutes`).
+- Type-bron: `stores/product-workspace/types.ts`.
+
+Auth/access-control wijzigt niet — de rearchitecture raakt alleen
+client-state, niet serverlaag-security.
+
+---
+
 ## Voorbeeldworkflow voor Claude Code
 
 1. **Probe:** `GET /api/health?db=1` — bevestig dat de service en DB bereikbaar zijn.

docs/patterns/workspace-store.md

@@ -0,0 +1,414 @@
+---
+title: "Workspace-store + realtime — bounded-context patroon"
+status: active
+audience: [ai-agent, contributor]
+language: nl
+last_updated: 2026-05-10
+when_to_read: "When adding a new bounded-context client store backed by SSE, or when modifying product/sprint workspace state."
+---
+
+# Patroon: workspace-store + realtime
+
+Sinds PBI-74 is `product-workspace-store` de blueprint voor client-state op een
+**bounded context** (één coherente workflow). Andere bounded contexts mogen
+hetzelfde patroon volgen — `sprint-workspace-store`, `solo-store`,
+`notifications-store`. Dit document beschrijft wanneer je een workspace-store
+opzet, hoe je 'm structureert, hoe SSE en de store samenwerken, en welke
+gotchas in code-comments hoort.
+
+Bron-ontwerp: [zustand-store-rearchitecture.md](../plans/zustand-store-rearchitecture.md).
+Referentie-implementatie: [stores/product-workspace/](../../stores/product-workspace/).
+
+---
+
+## Wanneer een workspace-store
+
+Eén store **per bounded context**, niet per pagina en niet één megastore.
+
+| Workflow | Store |
+|---|---|
+| Product backlog (PBI/story/task selectie + DnD) | `product-workspace-store` |
+| Sprint board | `sprint-workspace-store` (toekomstig, PBI > 74) |
+| Solo execution | `solo-store` |
+| Notifications/questions | `notifications-store` |
+| Idea grill/plan-flow | `idea-store` |
+| Lijst van producten | `products-store` (≠ active product) |
+
+Splits niet per panel; bundel niet over workflows.
+
+---
+
+## State-shape
+
+Vlak en **genormaliseerd**. Vijf slices:
+
+```ts
+{
+  context:    { active*Id }                  // huidige selectie
+  entities:   { *ById }                      // entity-maps per kind
+  relations:  { ids[], idsByParent }         // gesorteerde id-lijsten
+  loading:    { loaded*Ids, activeRequestId } // race-safe markers
+  sync:       { realtimeStatus, lastResyncAt, resyncReason }
+  pendingMutations: { [id]: { mutation, createdAt } }
+}
+```
+
+**Acties** zijn in dezelfde store:
+`hydrateSnapshot`, `setActive*`, `ensure*Loaded`, `applyRealtimeEvent`,
+`resyncActiveScopes`, `resyncLoadedScopes`,
+`applyOptimisticMutation`/`rollbackMutation`/`settleMutation`.
+
+Gebruik `zustand/middleware/immer`. Mutation-style (G3 — return nooit een
+nieuwe state uit een immer-recipe; muteer de draft).
+
+---
+
+## Selectors
+
+Module-level **`EMPTY`**-refs (G1) en `useShallow` voor lijsten (G2).
+
+```ts
+// stores/product-workspace/selectors.ts
+const EMPTY_PBIS: BacklogPbi[] = []
+
+export function selectVisiblePbis(s: Store): BacklogPbi[] {
+  if (s.relations.pbiIds.length === 0) return EMPTY_PBIS
+  return s.relations.pbiIds.map((id) => s.entities.pbisById[id]).filter(Boolean)
+}
+```
+
+```tsx
+// component
+import { useShallow } from 'zustand/react/shallow'
+import { selectVisiblePbis } from '@/stores/product-workspace/selectors'
+
+const pbis = useStore(useShallow(selectVisiblePbis))
+const activePbiId = useStore((s) => s.context.activePbiId) // primitive — geen useShallow
+```
+
+Single-value selectors (`selectActivePbi`) hebben geen `useShallow` nodig.
+
+---
+
+## ensure*Loaded — race-safe loaders
+
+Elke setter genereert een nieuwe `requestId`, schrijft 'm in
+`loading.activeRequestId`, en triggert de loader. De loader checkt **na de
+fetch** of de guard nog matcht — anders bail-out.
+
+```ts
+setActivePbi(pbiId) {
+  const requestId = newRequestId()
+  set((s) => {
+    s.context.activePbiId = pbiId
+    s.context.activeStoryId = null
+    s.context.activeTaskId = null
+    s.loading.activeRequestId = requestId
+  })
+  if (pbiId) void get().ensurePbiLoaded(pbiId, requestId)
+}
+
+async ensurePbiLoaded(pbiId, requestId) {
+  const stories = await fetchJson(`/api/pbis/${pbiId}/stories`)
+  if (requestId && get().loading.activeRequestId !== requestId) return
+  if (!Array.isArray(stories)) return
+  set((s) => { /* apply */ })
+}
+```
+
+**Belangrijke regels:**
+
+- Gebruik `get().method()` per call (G4) — nooit `state.method()` via een
+  gecaptured snapshot. Method-refs zijn niet stabiel over immer state-versies.
+- `fetch(url, { cache: 'no-store' })` op alle client-fetches.
+- Server read-routes: `export const dynamic = 'force-dynamic'`.
+
+---
+
+## SSE-hook beheert transport, store beheert betekenis
+
+```txt
+useXxxRealtime(activeId)
+-> opent /api/realtime/xxx?...
+-> parsed event
+-> dispatcht naar store.applyRealtimeEvent(event)
+-> beheert reconnect/backoff/status
+-> op 'ready' na (re)connect: telt cycles; latere ready triggert resync('reconnect')
+```
+
+```ts
+// applyRealtimeEvent regels
+known pbi/story/task event
+  → upsert + sort, parent-move bij wijziging parent_id
+  → idempotent: bestaande id bij INSERT → return
+  → DELETE → ruim child entities op + clear actieve selectie als die viel
+
+unknown entity met matching product_id, geen 'type' veld
+  → resyncActiveScopes('unknown-event')
+
+job/worker/heartbeat (heeft 'type' veld)
+  → negeer
+```
+
+**Idempotent:** een event dat al via een optimistic mutation is toegepast,
+mag geen dubbele insert of verkeerde rollback veroorzaken. INSERTs checken
+`if (entity exists) return`. UPDATEs zijn altijd merge-into-existing.
+
+Payload-contract: zie [realtime-notify-payload.md](./realtime-notify-payload.md).
+
+---
+
+## Hidden tab + reconnect resync
+
+EventSource blijft open als de tab `hidden` wordt — gemiste events worden
+opgehaald via een expliciete resync-laag.
+
+```ts
+// In de realtime-hook
+const onVisibility = () => {
+  if (document.visibilityState === 'visible' && sourceRef.current === null) {
+    connect() // alleen als de stream weg is (b.v. server hard-close na 240s)
+  }
+}
+// Geen close() bij hidden.
+
+source.addEventListener('ready', () => {
+  readyCountRef.current += 1
+  if (readyCountRef.current > 1) {
+    void store.resyncActiveScopes('reconnect')
+  }
+})
+```
+
+```ts
+// useWorkspaceResync — visibility + online
+useEffect(() => {
+  const onVisibility = () => {
+    if (document.visibilityState === 'visible') {
+      void store.resyncActiveScopes('visible')
+    }
+  }
+  const onOnline = () => void store.resyncActiveScopes('reconnect')
+
+  document.addEventListener('visibilitychange', onVisibility)
+  window.addEventListener('online', onOnline)
+  return () => { /* remove */ }
+}, [])
+```
+
+**Mount in dezelfde wrapper als de realtime-hook.** Doe nooit alleen het
+sluiten-op-hidden weghalen zonder de resync-laag erbij — dan verlies je het
+vangnet.
+
+`resyncActiveScopes` triggert alleen de loaders die gekoppeld zijn aan de
+huidige selectie:
+
+```ts
+async resyncActiveScopes(reason) {
+  const ctx = get().context
+  const tasks: Promise<void>[] = []
+  if (ctx.activeProduct?.id) tasks.push(get().ensureProductLoaded(ctx.activeProduct.id))
+  if (ctx.activePbiId)       tasks.push(get().ensurePbiLoaded(ctx.activePbiId))
+  if (ctx.activeStoryId)     tasks.push(get().ensureStoryLoaded(ctx.activeStoryId))
+  if (ctx.activeTaskId)      tasks.push(get().ensureTaskLoaded(ctx.activeTaskId))
+  set((s) => { s.sync.lastResyncAt = Date.now(); s.sync.resyncReason = reason })
+  await Promise.allSettled(tasks)
+}
+```
+
+---
+
+## LocalStorage = restore-hint, niet waarheid
+
+Selectie-id's worden gepersisteerd om bij cold reload de vorige selectie te
+herstellen, **maar de hint wordt pas toegepast nadat ensure-load is gelukt
+en de hint-id bevestigd is in `entities.byId`**.
+
+```ts
+setActiveProduct(product) {
+  set((s) => { s.context.activeProduct = product; ... })
+  writeProductHint(product?.id ?? null)
+
+  if (product) {
+    void (async () => {
+      await get().ensureProductLoaded(product.id, requestId)
+      if (get().loading.activeRequestId !== requestId) return
+      const hint = readHints().perProduct[product.id]?.lastActivePbiId
+      if (hint && get().entities.pbisById[hint]) {
+        get().setActivePbi(hint)  // cascade — die doet zelfde voor story
+      }
+    })()
+  }
+}
+```
+
+**Geen `setTimeout(0)` of microtask-trick.** De fetch is dan nog niet klaar,
+de validatie `entities.byId[hint]` faalt altijd. Chain altijd `await
+ensureXxxLoaded` en valideer in dezelfde `requestId`-cycle.
+
+**URL wint van hint.** Maak een client-component (b.v.
+[`UrlTaskSync`](../../components/backlog/url-task-sync.tsx)) die op mount
+`useSearchParams().get('editTask')` leest, de hint overschrijft via
+`writeTaskHint`, en `setActiveTask` aanroept. De restore-flow leest de
+task-hint pas na drie ensure-awaits, dus de URL-write komt altijd eerder.
+
+---
+
+## Optimistic mutations
+
+Voor DnD en status-toggles. De store registreert alleen het rollback-snapshot;
+de component muteert state direct én roept de server aan.
+
+```tsx
+function handleDragEnd(event) {
+  const store = useStore.getState()
+  const prevOrder = [...store.relations.pbiIds]
+  const newOrder = arrayMove(prevOrder, oldIndex, newIndex)
+
+  // 1. Snapshot voor rollback
+  const mutationId = store.applyOptimisticMutation({
+    kind: 'pbi-order',
+    prevPbiIds: prevOrder,
+  })
+
+  // 2. Optimistisch toepassen
+  useStore.setState((s) => { s.relations.pbiIds = newOrder })
+
+  // 3. Server bevestigt (of niet)
+  startTransition(async () => {
+    const result = await reorderPbisAction(productId, newOrder)
+    const st = useStore.getState()
+    if (result.success) {
+      st.settleMutation(mutationId)
+    } else {
+      st.rollbackMutation(mutationId)
+      toast.error('Volgorde opslaan mislukt')
+    }
+  })
+}
+```
+
+**Cross-priority drag** vereist twee mutaties: een `pbi-order` voor de lijst
+plus een `entity-patch` voor de priority op de PBI zelf. Beide settle/rollback
+samen.
+
+**SSE-echo van een net optimistisch toegepaste wijziging** moet idempotent
+zijn — INSERT → bestaat al → return; UPDATE → merge into existing.
+
+---
+
+## API endpoints
+
+Voor elke `ensure*Loaded` een GET-route met:
+
+- Auth via `authenticateApiRequest` (Bearer-token of iron-session cookie).
+- Access-control via `productAccessFilter(userId)` voor product-context;
+  `getAccessibleProduct` voor explicit guards.
+- `export const dynamic = 'force-dynamic'`.
+- Status-vertaling via `taskStatusToApi` / `storyStatusToApi` /
+  `pbiStatusToApi` (DB UPPER_SNAKE → API lowercase).
+
+Referentie:
+[GET /api/products/:id/backlog](../../app/api/products/[id]/backlog/route.ts),
+[GET /api/pbis/:id/stories](../../app/api/pbis/[id]/stories/route.ts),
+[GET /api/stories/:id/tasks](../../app/api/stories/[id]/tasks/route.ts),
+[GET /api/tasks/:id](../../app/api/tasks/[id]/route.ts).
+
+`TaskDetail` shape extends `BacklogTask` met `_detail: true` plus extra
+velden (`implementation_plan`, `acceptance_criteria`, `requires_opus`,
+`verify_only`, `verify_required`). Gebruik de `isDetail()` typeguard om de
+extra velden te tonen.
+
+---
+
+## Tests
+
+Vitest + jsdom; setup in [`tests/setup.ts`](../../tests/setup.ts):
+
+- `MemoryStorage` shim voor localStorage (G6 — vitest 4 + jsdom 29 mist 'm
+  als configurable global).
+- `globalThis.fetch` herconfigureerbaar gemaakt zodat `vi.spyOn` werkt
+  (anders krijg je `Cannot redefine property: fetch`).
+- Default fetch-stub die `null` JSON returnt — voorkomt unhandled rejections
+  uit fire-and-forget `ensure*Loaded` calls die in tests niet expliciet
+  gemockt zijn. Tests overrulen met `vi.spyOn(globalThis, 'fetch')` per case.
+- `mockImplementation` (G8) — niet `mockResolvedValue` — anders is de
+  Response-body na de eerste `.json()` weg.
+
+```ts
+// G5: snapshot original actions module-level, restore in beforeEach
+const originalActions = (() => {
+  const s = useStore.getState()
+  return { /* alle action-refs */ }
+})()
+
+function resetStore() {
+  useStore.setState((s) => {
+    Object.assign(s, initialDataSlices)
+    Object.assign(s, originalActions)
+  })
+}
+
+beforeEach(resetStore)
+```
+
+**Acties mocken:** gebruik `setState((s) => { s.method = vi.fn() })`. Niet
+`vi.spyOn(state, 'method')` — de immer-frozen state is niet redefinable.
+
+**Verplichte test-cases per workspace-store:**
+
+- `hydrateSnapshot` vult entities + relations met sortering.
+- Selection cascade: `setActivePbi` reset story+task; `setActiveStory` reset
+  task.
+- `setActiveProduct(null)` ruimt entities en relations op.
+- `applyRealtimeEvent` pbi/story/task `I|U|D` met sortering en parent-move.
+- Event voor ander `product_id` wordt genegeerd.
+- Unknown entity met matching product → `resyncActiveScopes('unknown-event')`
+  trigger.
+- Job/worker/heartbeat/question events met `type`-veld → geen resync.
+- Delete-cleanup van actieve selectie.
+- Race-safe `ensure*Loaded` met requestId-guard (oude in-flight mag niet
+  nieuwere selectie overschrijven).
+- `ensureTaskLoaded` zet `_detail: true`.
+- `resyncActiveScopes` triggert ensure-keten met juiste URLs en zet
+  `lastResyncAt` + `resyncReason`.
+- localStorage restore-hints per setter.
+- Hint die niet (meer) in entities zit wordt genegeerd.
+- Optimistic mutation rollback/settle/SSE-echo idempotent.
+
+---
+
+## Gotchas — comment-template voor in code
+
+Documenteer deze in code via comments boven de fix.
+
+| # | Symptoom | Fix |
+|---|---|---|
+| **G1** | "Maximum update depth exceeded" — `s.byId[x] ?? []` levert nieuwe array per render | Module-level `EMPTY` const als fallback |
+| **G2** | Component re-rendert op iedere store-mutatie ondanks dat z'n data niet wijzigt | `useShallow(selectXxx)` voor lijsten |
+| **G3** | Hele state lijkt gewist na een `setState((s) => ({ context: ... }))` | Gebruik mutation-style: `setState((s) => { s.context.x = y })` (immer recipe muteert draft) |
+| **G4** | "method is not a function" in async context, of inconsistente state-mutaties | `get().method()` per call; nooit `const m = state.method` cachen |
+| **G5** | Tests beïnvloeden elkaar via `setState({ resyncActiveScopes: vi.fn() })` | `originalActions` snapshot op module-load + restore in `beforeEach` |
+| **G6** | `localStorage.clear is not a function` in vitest | `MemoryStorage` shim in `tests/setup.ts` |
+| **G7** | "Failed to parse URL from /api/..." in test-fetch | Mock fetch via `vi.spyOn(globalThis, 'fetch')` of stub in setup |
+| **G8** | "Body is unusable: Body has already been read" | `vi.fn().mockImplementation(() => Promise.resolve(new Response(...)))` — niet `mockResolvedValue` met een vooraf-gemaakte Response |
+
+---
+
+## Migratiepad voor een nieuwe workspace-store
+
+Volg dezelfde 8 stappen als PBI-74 (zie
+[zustand-workspace-store-implementation.md](../plans/zustand-workspace-store-implementation.md)):
+
+1. Skelet — types, store, selectors, restore + tests; geen UI-impact.
+2. Hydratie overstappen (parallel naast bestaande store).
+3. Componenten omzetten — `useShallow` voor lijsten, `setActiveX` setters.
+4. Race-safe loaders + restore-hints + URL-prioriteit.
+5. Hidden-tab + reconnect-resync (één PR — anders verlies je vangnet).
+6. Unknown-event filter (`isUnknownEntityEvent`).
+7. Cache-headers + LIST-endpoints (`force-dynamic`, `cache: 'no-store'`).
+8. Oude store opruimen.
+
+Stap 9 ("sprint-workspace-store") is de toepassing van dit patroon op de
+sprint-flow — kan starten zodra `product-workspace-store` enkele weken
+stabiel in productie staat.

docs/patterns/zustand-optimistic.md

@@ -3,34 +3,99 @@ title: "Zustand optimistische update + rollback"
 status: active
 audience: [ai-agent, contributor]
 language: nl
-last_updated: 2026-05-03
+last_updated: 2026-05-10
-when_to_read: "When adding client-side state mutations that need optimistic UI and rollback."
+when_to_read: "When adding client-side state mutations that need optimistic UI and rollback (DnD, status toggles)."
 ---
 
 # Patroon: Zustand optimistische update + rollback
 
-Gebruik dit patroon bij elke dnd-kit `onDragEnd` handler.
+Sinds PBI-74 lopen optimistic mutations via `applyOptimisticMutation`/
+`rollbackMutation`/`settleMutation` op de **workspace-store**. Het bredere
+patroon (store-design, SSE-integratie, restore-hints, tests) staat in
+[workspace-store.md](./workspace-store.md). Dit document beschrijft het
+DnD/status-mutation flow specifiek.
 
-```ts
+## Patroon
-const { pbiOrder, reorderPbis, rollbackPbis } = usePlannerStore()
 
-async function handleDragEnd(event: DragEndEvent) {
+1. Snapshot rollback-info via `applyOptimisticMutation` — krijgt `mutationId`.
+2. Pas state direct aan via `setState`.
+3. Server-actie aanroepen.
+4. Op success: `settleMutation(mutationId)` (ruimt pending-record op).
+5. Op error: `rollbackMutation(mutationId)` (herstelt vorige state + toast).
+
+Cross-priority drag vereist twee mutaties (order + entity-patch) die samen
+settlen of rollbacken.
+
+## Voorbeeld — PBI reorder
+
+```tsx
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+
+function handleDragEnd(event: DragEndEvent) {
   const { active, over } = event
   if (!over || active.id === over.id) return
 
-  const prevOrder = [...pbiOrder[productId]]
+  const store = useProductWorkspaceStore.getState()
-  const newOrder = arrayMove(prevOrder, oldIndex, newIndex)
+  const prevOrder = [...store.relations.pbiIds]
+  const oldIndex = prevOrder.indexOf(active.id as string)
+  const newIndex = prevOrder.indexOf(over.id as string)
+  if (oldIndex === -1 || newIndex === -1) return
+  const newOrder = arrayMove([...prevOrder], oldIndex, newIndex)
 
-  // 1. Optimistisch updaten (direct zichtbaar voor gebruiker)
+  // 1. Snapshot rollback-info
-  reorderPbis(productId, newOrder)
+  const mutationId = store.applyOptimisticMutation({
+    kind: 'pbi-order',
+    prevPbiIds: prevOrder,
+  })
 
-  // 2. Persisteren via Server Action
+  // 2. Optimistisch toepassen
-  const result = await reorderPbisAction(productId, newOrder)
+  useProductWorkspaceStore.setState((s) => {
+    s.relations.pbiIds = newOrder
+  })
 
-  // 3. Rollback bij fout
+  // 3-5. Server bevestigt of niet
-  if (!result.success) {
+  startTransition(async () => {
-    rollbackPbis(productId, prevOrder)
+    const result = await reorderPbisAction(productId, newOrder)
-    toast.error('Volgorde opslaan mislukt')
+    const st = useProductWorkspaceStore.getState()
-  }
+    if (result.success) {
+      st.settleMutation(mutationId)
+    } else {
+      st.rollbackMutation(mutationId)
+      toast.error('Volgorde opslaan mislukt')
+    }
+  })
 }
 ```
+
+## Voorbeeld — entity-patch (priority-wijziging)
+
+```tsx
+const prevPbi = store.entities.pbisById[id]
+const patchMutationId = store.applyOptimisticMutation({
+  kind: 'entity-patch',
+  entity: 'pbi',
+  id,
+  prev: prevPbi,
+})
+useProductWorkspaceStore.setState((s) => {
+  const pbi = s.entities.pbisById[id]
+  if (pbi) pbi.priority = newPriority
+})
+// settle/rollback identiek aan order-flow
+```
+
+## Mutation-soorten
+
+| `kind` | Rollback-data | Use-case |
+|---|---|---|
+| `pbi-order` | `prevPbiIds` | DnD reorder van PBI's |
+| `story-order` | `pbiId` + `prevStoryIds` | DnD reorder van stories binnen een PBI |
+| `task-order` | `storyId` + `prevTaskIds` | DnD reorder van tasks binnen een story |
+| `entity-patch` | `entity` + `id` + `prev` (volledig vorig record of `undefined` voor delete-rollback) | Property-wijzigingen (priority, status), of optimistic delete/undelete |
+
+## SSE-echo idempotent verwerken
+
+Wanneer de server bevestigt en de NOTIFY-trigger het bijbehorende event
+emitteert, mag `applyRealtimeEvent` **geen dubbele insert** veroorzaken en
+**geen rollback triggeren**. INSERTs checken bestaan; UPDATEs mergen
+into-existing. Zie `applyRealtimeEvent` in [`stores/product-workspace/store.ts`](../../stores/product-workspace/store.ts).

docs/plans/lees-de-readme-md-validated-book.md

@@ -1,8 +1,16 @@
 # Scrum4Me-Research — Zustand rearchitecture (reset + execute)
 
+> **Scope:** dit plan is geschreven voor de research-repo
+> [`madhura68/Scrum4Me-Research`](https://github.com/madhura68/Scrum4Me-Research),
+> niet voor dit hoofdproject. Bestandsverwijzingen die naar
+> `stores/data-store.ts`, `hooks/use-event-stream.ts`,
+> `components/*-select.tsx` etc. wijzen, bestaan in de research-repo —
+> niet hier. Ze staan in `code`-tags zodat de doc-link-checker ze niet
+> probeert te resolven.
+
 ## Context
 
-Het bestaande [docs/plans/zustand-store-rearchitecture.md](docs/plans/zustand-store-rearchitecture.md) beschrijft een doel-architectuur (`product-workspace-store` met genormaliseerde entities, race-safe loaders, resync-laag, optimistic mutations). De research-repo is dé plek om dat eerst te testen voordat het in `Scrum4Me/` belandt.
+Het bestaande [zustand-store-rearchitecture.md](./zustand-store-rearchitecture.md) beschrijft een doel-architectuur (`product-workspace-store` met genormaliseerde entities, race-safe loaders, resync-laag, optimistic mutations). De research-repo is dé plek om dat eerst te testen voordat het in `Scrum4Me/` belandt.
 
 Probleem nu: de research-repo wijkt af van het hoofdproject. Mijn custom `data-store.ts` lijkt qua vorm op de doel-architectuur, maar springt over de baseline heen. We willen aantonen dat de migratie *vanaf* de huidige Scrum4Me-patronen werkt, niet vanaf een verzonnen tussenvorm.
 
@@ -10,8 +18,8 @@ Dus: eerst de research-repo terugbrengen naar dezelfde stores/hooks/routes als S
 
 ## Bron-documenten
 
-- **Doel-architectuur**: [docs/plans/zustand-store-rearchitecture.md](docs/plans/zustand-store-rearchitecture.md) (in research-repo). Dit plan voert dat document uit; herhaalt het niet.
+- **Doel-architectuur**: [zustand-store-rearchitecture.md](./zustand-store-rearchitecture.md) (in research-repo). Dit plan voert dat document uit; herhaalt het niet.
-- **Conventies**: [CLAUDE.md](../Scrum4Me/CLAUDE.md) hoofdproject. Taal NL, MD3 tokens, `@base-ui/react` render-prop, `*-server.ts`, enum UPPER_SNAKE↔lowercase via `lib/task-status.ts`.
+- **Conventies**: [CLAUDE.md](../../CLAUDE.md) hoofdproject. Taal NL, MD3 tokens, `@base-ui/react` render-prop, `*-server.ts`, enum UPPER_SNAKE↔lowercase via `lib/task-status.ts`.
 
 ## Drie-faseplan
 
@@ -20,10 +28,10 @@ Dus: eerst de research-repo terugbrengen naar dezelfde stores/hooks/routes als S
 Doel: onze research-pagina werkt op exact dezelfde store/hook/route-vorm als het hoofdproject, met identiek gedrag.
 
 **Verwijderen** (research-repo):
-- [stores/data-store.ts](stores/data-store.ts) — mijn megastore
+- `stores/data-store.ts` (research-repo) — mijn megastore
-- [hooks/use-event-stream.ts](hooks/use-event-stream.ts) — vervangen door `use-backlog-realtime.ts`
+- `hooks/use-event-stream.ts` (research-repo) — vervangen door `use-backlog-realtime.ts`
-- [hooks/use-browser-presence.ts](hooks/use-browser-presence.ts) — niet in main, drop voor reset
+- `hooks/use-browser-presence.ts` (research-repo) — niet in main, drop voor reset
-- [app/api/realtime/events/route.ts](app/api/realtime/events/route.ts) — vervangen door `app/api/realtime/backlog/route.ts`
+- `app/api/realtime/events/route.ts` (research-repo) — vervangen door `app/api/realtime/backlog/route.ts`
 - Mijn custom `loadX/resyncAll`-paden in selectie-componenten
 
 **Kopiëren uit `/Users/janpetervisser/Development/Scrum4Me/`** (1-op-1 of stripped van auth):
@@ -48,12 +56,12 @@ Doel: onze research-pagina werkt op exact dezelfde store/hook/route-vorm als het
 - `GET /api/tasks/[id]`
 
 **Componenten herschrijven**:
-- [components/product-select.tsx](components/product-select.tsx) → leest `useProductsStore`, schrijft naar `useProductStore.setCurrentProduct`
+- `components/product-select.tsx` (research-repo) → leest `useProductsStore`, schrijft naar `useProductStore.setCurrentProduct`
-- [components/pbi-select.tsx](components/pbi-select.tsx) → leest `useBacklogStore` (filter op currentProduct), `useSelectionStore.selectPbi`. Triggert fetch op product-mount via een `useBacklogLoader`-helper die initial data binnenhaalt.
+- `components/pbi-select.tsx` (research-repo) → leest `useBacklogStore` (filter op currentProduct), `useSelectionStore.selectPbi`. Triggert fetch op product-mount via een `useBacklogLoader`-helper die initial data binnenhaalt.
-- [components/story-select.tsx](components/story-select.tsx) → idem voor stories
+- `components/story-select.tsx` (research-repo) → idem voor stories
-- [components/tasks-table.tsx](components/tasks-table.tsx) → leest `tasksByStory[selectedStoryId]`. **Max 10 rijen, scrollbaar** (al ingebouwd, behouden)
+- `components/tasks-table.tsx` (research-repo) → leest `tasksByStory[selectedStoryId]`. **Max 10 rijen, scrollbaar** (al ingebouwd, behouden)
-- [components/task-detail-card.tsx](components/task-detail-card.tsx) → fetcht task detail apart (geen full-fat backlog veld; matcht main's `tasks/[id]` route)
+- `components/task-detail-card.tsx` (research-repo) → fetcht task detail apart (geen full-fat backlog veld; matcht main's `tasks/[id]` route)
-- [components/event-stream-panel.tsx](components/event-stream-panel.tsx) → blijft bestaan voor research-doel (event-tap), maar luistert nu mee op dezelfde EventSource via `use-backlog-realtime` (of een tweede readonly listener); selecteerbare events met JSON-detail rechts blijven. Twee checkboxes (Postgres / Browser). Truncate met ellipsis in de lijst.
+- `components/event-stream-panel.tsx` (research-repo) → blijft bestaan voor research-doel (event-tap), maar luistert nu mee op dezelfde EventSource via `use-backlog-realtime` (of een tweede readonly listener); selecteerbare events met JSON-detail rechts blijven. Twee checkboxes (Postgres / Browser). Truncate met ellipsis in de lijst.
 
 **Werkwijzen (verifiëren tijdens reset)**:
 - Comments en UI-tekst NL
@@ -69,7 +77,7 @@ Doel: onze research-pagina werkt op exact dezelfde store/hook/route-vorm als het
 
 ### Fase B — Rearchitecture uitvoeren
 
-Volgt de 15 stappen uit [docs/plans/zustand-store-rearchitecture.md](docs/plans/zustand-store-rearchitecture.md) §Implementatiepad. Concreet voor de research-repo:
+Volgt de 15 stappen uit [zustand-store-rearchitecture.md](./zustand-store-rearchitecture.md) §Implementatiepad. Concreet voor de research-repo:
 
 1. **Map** `stores/product-workspace/` aanmaken (factory + provider + selectors).
 2. **`activeProduct`** wordt nu nog gespiegeld vanuit `useProductStore`; voor de research-pagina geen layout/server-side bepaling — we lezen het uit de pulldown-state.
@@ -134,10 +142,10 @@ Volgt de 15 stappen uit [docs/plans/zustand-store-rearchitecture.md](docs/plans/
 ## Bestandsmutaties (overzicht)
 
 ### Verwijderen na Fase A
-- [stores/data-store.ts](stores/data-store.ts)
+- `stores/data-store.ts` (research-repo)
-- [hooks/use-event-stream.ts](hooks/use-event-stream.ts)
+- `hooks/use-event-stream.ts` (research-repo)
-- [hooks/use-browser-presence.ts](hooks/use-browser-presence.ts) — komt deels terug in Fase B als helper voor visibility/online resync trigger
+- `hooks/use-browser-presence.ts` (research-repo) — komt deels terug in Fase B als helper voor visibility/online resync trigger
-- [app/api/realtime/events/route.ts](app/api/realtime/events/route.ts)
+- `app/api/realtime/events/route.ts` (research-repo)
 
 ### Toevoegen Fase A (uit Scrum4Me)
 - `stores/backlog-store.ts`
@@ -174,7 +182,7 @@ Volgt de 15 stappen uit [docs/plans/zustand-store-rearchitecture.md](docs/plans/
 6. Vergelijk: `diff Scrum4Me/stores/backlog-store.ts Scrum4Me-Research/stores/backlog-store.ts` → identiek (modulo lokale interface-uitbreidingen waar gedocumenteerd)
 
 ### Na Fase B (target)
-Alle acceptatiecriteria uit [docs/plans/zustand-store-rearchitecture.md §Acceptatiecriteria](docs/plans/zustand-store-rearchitecture.md):
+Alle acceptatiecriteria uit [zustand-store-rearchitecture.md §Acceptatiecriteria](./zustand-store-rearchitecture.md):
 - Eén waarheid per entity in de store ✓
 - Selectors als enige UI-leesweg ✓
 - SSE patcht zonder full-page refresh ✓

docs/plans/zustand-workspace-store-implementation.md

@@ -0,0 +1,177 @@
+---
+title: "Zustand workspace-store implementatieplan (PBI-74)"
+status: ready-to-execute
+audience: [maintainer, contributor, ai-agent]
+language: nl
+last_updated: 2026-05-09
+revision: 1
+---
+
+# Zustand workspace-store implementatieplan
+
+PBI in Scrum4Me-MCP: **PBI-74** — _Zustand store rearchitecture — product- en sprint-workspace_.
+
+Bron-ontwerp (architectuur en gotchas): [zustand-store-rearchitecture.md](./zustand-store-rearchitecture.md) revisie 3.
+
+Dit document koppelt de stories en taken in MCP aan de implementatie. Per story acceptatiecriteria; per taak een concrete deliverable. Alle items staan in MCP op `OPEN`/`TO_DO`. Geen executie tot expliciete trigger ("voer Story 1 uit").
+
+## Context
+
+De client-state ligt over vier los gegroeide stores: `backlog-store`, `planner-store`, `selection-store`, `product-store`. Vier zwakheden:
+
+- SSE sluit op tab `hidden` zonder resync bij `visible` — gemiste events blijven gemist.
+- Geen reconcile bij reconnect (Postgres NOTIFY heeft geen replay).
+- Onbekende entity-events worden stil genegeerd.
+- LocalStorage soms behandeld als waarheid i.p.v. restore-hint.
+- Geen race-safe loaders — trage fetch van oude selectie kan nieuwste overschrijven.
+
+De rearchitecture lost dit op via één `product-workspace-store` (en analoog `sprint-workspace-store`) met genormaliseerde entity-maps, race-safe `ensure*Loaded` met `activeRequestId`-guard, expliciete resync-laag (visible/reconnect/unknown-event), idempotente SSE-application en localStorage als pure restore-hint.
+
+## Aanpak
+
+- Eén PBI ([PBI-74](./zustand-store-rearchitecture.md)).
+- Negen stories die mappen op de stappen 1-9 in het bron-ontwerp.
+- Granulariteit Story 3 = één story met taken per component.
+- Story 5 in één PR (visibility-handling + resync horen samen).
+- Per story: PR, `npm run verify && npm run build` groen, status DONE pas na merge.
+- Branch: `feat/zustand-workspace-store` (één branch voor alle stories).
+
+## Stories en taken
+
+| # | Story | MCP | Taken |
+|---|---|---|---|
+| 1 | Skelet + test-infrastructuur | [ST-1318](./zustand-store-rearchitecture.md) | T-837 … T-843 (7) |
+| 2 | Hydratie overstappen (parallel-running) | ST-1319 | T-844 … T-847 (4) |
+| 3 | Componenten omzetten naar workspace-store | ST-1320 | T-848 … T-855 (8) |
+| 4 | Race-safe loaders en restore-hints | ST-1321 | T-856 … T-860 (5) |
+| 5 | Hidden-tab + reconnect resync (één PR) | ST-1322 | T-861 … T-864 (4) |
+| 6 | Unknown-event fallback | ST-1323 | T-865 … T-867 (3) |
+| 7 | Cache-headers en read-routes | ST-1324 | T-868 … T-871 (4) |
+| 8 | Oude stores opruimen | ST-1325 | T-872 … T-878 (7) |
+| 9 | Sprint-workspace-store | ST-1326 | T-879 … T-884 (6) |
+
+Totaal: 48 taken.
+
+### Story 1 — Skelet + test-infrastructuur
+
+**Doel:** nieuwe store + selectors + restore-utils met volledige unit-test-suite, nog zonder UI-consumenten.
+
+**Belangrijkste taken:**
+- T-837 — Vitest naar jsdom + `tests/setup.ts` met MemoryStorage (G6).
+- T-838/839/840/841 — `stores/product-workspace/{types,store,selectors,restore}.ts`.
+- T-842 — Volledige test-suite per §Testing setup-checklist (G5/G7/G8).
+- T-843 — API endpoint-audit voor `ensure*Loaded` URLs.
+
+**Acceptatie:** alle test-cases groen, geen UI-impact.
+
+### Story 2 — Hydratie overstappen
+
+**Doel:** `BacklogHydrationWrapper` en `useBacklogRealtime` voeden zowel oude store als nieuwe store. Componenten lezen nog uit oude.
+
+**Taken:** T-844 (wrapper dual-dispatch), T-845 (realtime dual-dispatch), T-846 (dev-only fingerprint verifyer), T-847 (productpicker → setActiveProduct).
+
+**Acceptatie:** schaduw-store inhoud matcht oude store na elk SSE-event.
+
+### Story 3 — Componenten omzetten
+
+**Doel:** componenten lezen uit nieuwe workspace-store; oude stores hebben geen UI-consumenten meer.
+
+**Taken per component:** T-848 (split-pane), T-849 (pbi-list), T-850 (story-panel), T-851 (task-panel), T-852 (start-sprint-button), T-853 (set-current-product). Plus T-854 (G1/G2-audit) en T-855 (integration-tests bijwerken).
+
+**Acceptatie:** geen "Maximum update depth" warnings; oude store-imports alleen nog in tests die in Story 8 verdwijnen.
+
+### Story 4 — Race-safe loaders en restore-hints
+
+**Doel:** `ensure*Loaded` met `activeRequestId`-guard; localStorage hints met validatie.
+
+**Taken:** T-856 (guard), T-857 (restore-flow met await ensure-chain), T-858 (hint-persistentie), T-859 (URL-prioriteit), T-860 (race-safety tests).
+
+**Acceptatie:** trage fetch + her-selectie corrumpeert nooit; cold reload restoret zonder fout.
+
+### Story 5 — Hidden-tab + reconnect resync (één PR)
+
+**Doel:** SSE blijft open op hidden; resync via expliciete laag.
+
+**Taken:** T-861 (geen close op hidden), T-862 (ready-event triggert resync na reconnect), T-863 (`useWorkspaceResync` hook), T-864 (tests).
+
+**Acceptatie:** hidden→visible en reconnect herstellen gemiste wijzigingen in één cyclus.
+
+### Story 6 — Unknown-event fallback
+
+**Doel:** onbekende entity-events triggeren resync; job/worker noise wordt genegeerd.
+
+**Taken:** T-865 (`isUnknownEntityEvent` filter), T-866 (resync-trigger), T-867 (negatieve filter-tests).
+
+**Acceptatie:** directe DB UPDATE zonder herkenbare delta-event wordt zichtbaar binnen één resync; job-events triggeren geen resync.
+
+### Story 7 — Cache-headers en read-routes
+
+**Doel:** geen stale data uit Next/browser cache.
+
+**Taken:** T-868 (`cache: 'no-store'`), T-869 (`force-dynamic` audit), T-870 (LIST-endpoints toevoegen waar nodig), T-871 (SSE-route ready-event coverage).
+
+**Acceptatie:** response headers in productie tonen `cache-control: no-store`; LIST-endpoints bestaan voor alle `ensure*Loaded`.
+
+### Story 8 — Oude stores opruimen
+
+**Doel:** vier oude stores verwijderd.
+
+**Taken:** T-872 (grep), T-873/874/875/876 (delete vier files), T-877 (oude tests migreren), T-878 (`stores/products-store.ts` blijft + dev-fingerprint cleanup).
+
+**Acceptatie:** grep `useBacklogStore|usePlannerStore|useSelectionStore|useProductStore` = 0; `npm run verify && npm run build` groen.
+
+### Story 9 — Sprint-workspace-store
+
+**Doel:** zelfde patroon op sprint-workflow toegepast.
+
+**Taken:** T-879 (skelet), T-880 (hydratie+realtime), T-881 (componenten), T-882 (race-safe + restore + resync + unknown-event in één keer), T-883 (cleanup oude sprint-state), T-884 (E2E sprint-board verificatie).
+
+> **Aanbeveling per ontwerpdoc:** start Story 9 pas nadat product-workspace enkele weken stabiel in productie staat. PBI-74 sluit pas wanneer Story 9 ook merged is.
+
+## Critical files
+
+**Te wijzigen:**
+- `vitest.config.ts` — env naar jsdom, setupFiles
+- nieuw: `tests/setup.ts` — MemoryStorage, restoreAllMocks
+- nieuw: `stores/product-workspace/{types,store,selectors,restore}.ts`
+- nieuw: `stores/sprint-workspace/{types,store,selectors,restore}.ts`
+- nieuw: `lib/realtime/use-workspace-resync.ts`
+- `components/backlog/backlog-hydration-wrapper.tsx`
+- `lib/realtime/use-backlog-realtime.ts`
+- `components/backlog/backlog-split-pane.tsx`, `pbi-list.tsx`, `story-panel.tsx`, `task-panel.tsx`
+- `components/.../start-sprint-button.tsx`, `set-current-product.tsx`
+- read-routes onder `app/api/...` voor PBI/story/task LIST + detail
+- te verwijderen in Story 8: `stores/{backlog,planner,selection,product}-store.ts`
+
+**Te hergebruiken (geen wijziging):**
+- `lib/product-access.ts` — `getAccessibleProduct`, blijft auth/access-bron
+- `app/api/realtime/backlog/route.ts` — `ready`-event al aanwezig
+- `docs/patterns/realtime-notify-payload.md` — payload-contract
+- `docs/patterns/route-handler.md` — REST patroon
+- `stores/products-store.ts`, `stores/solo-store.ts`, `stores/notifications-store.ts`, `stores/idea-store.ts`, `stores/jobs-store.ts` — blijven ongewijzigd
+
+## Verificatie per story
+
+- **Story 1:** Vitest groen voor alle test-cases (hydrate, cascade, realtime, ensureLoaded race, resync, restore-hints, optimistic mutation).
+- **Story 2:** dev-server, productpagina, fingerprint match in console.
+- **Story 3:** klik door 3 panels, DnD test, geen "Maximum update depth"-warnings.
+- **Story 4:** staging — cold reload, throttle fetch + her-selecteer.
+- **Story 5:** tab hidden > 30s + terug → resync zichtbaar; netwerk uit/aan → reconnect+resync.
+- **Story 6:** DB UPDATE op story zonder delta-event → zichtbaar binnen 1 resync; job-events negeren resync.
+- **Story 7:** response headers `cache-control: no-store`; tweede pageload toont verse data.
+- **Story 8:** grep oude store-imports = 0; `npm run verify && npm run build` groen.
+- **Story 9:** sprint-board flow analoog Story 1-8 verifications.
+
+**Eind-acceptatie PBI-74:** alle items uit §Acceptatiecriteria van [zustand-store-rearchitecture.md](./zustand-store-rearchitecture.md) (regels 727-746) behaald.
+
+## Workflow per story
+
+1. `git checkout -b feat/zustand-workspace-store` (eerste story); blijf op deze branch tot expliciete cut.
+2. `mcp__scrum4me__get_claude_context` → pak next story uit PBI-74.
+3. Voer taken uit in `sort_order`; update status per taak via `mcp__scrum4me__update_task_status`.
+4. Lees relevante bestanden + patronen vóór begin (zie §Critical files).
+5. `npm run verify && npm run build` per laag.
+6. Commit per laag (`git add -A && git commit`); geen push tussendoor.
+7. Story-status sluit zodra alle taken `DONE`.
+8. Lege story-queue → `git push -u origin feat/zustand-workspace-store` + `gh pr create`.
+9. Per story een eigen PR; merge één voor één.

lib/realtime/use-backlog-realtime.ts

@@ -1,11 +1,19 @@
 'use client'
 
-// ST-1115: Client hook for the backlog 3-pane SSE stream.
+// ST-1115 / PBI-74: Client hook for the backlog 3-pane SSE stream.
 // Mounts in BacklogHydrationWrapper so it survives Server Action refreshes.
-// Dispatches pbi/story/task change events into useBacklogStore.applyChange.
+// Dispatches pbi/story/task change events into useProductWorkspaceStore.
+//
+// T-861: stream blijft open op tab hidden. Per spec werkt EventSource gewoon
+// door als de browser het toelaat — gemiste events worden opgehaald via
+// resyncActiveScopes('visible') uit useWorkspaceResync.
+// T-862: bij latere 'ready' events (post-reconnect) triggeren we
+// resyncActiveScopes('reconnect') zodat events die tijdens disconnect zijn
+// gemist, alsnog binnenkomen.
 
 import { useEffect, useRef } from 'react'
-import { useBacklogStore } from '@/stores/backlog-store'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+import type { ProductRealtimeEvent } from '@/stores/product-workspace/types'
 
 const BACKOFF_START_MS = 1_000
 const BACKOFF_MAX_MS = 30_000
@@ -20,6 +28,7 @@ export function useBacklogRealtime(productId: string | null) {
   const sourceRef = useRef<EventSource | null>(null)
   const backoffRef = useRef<number>(BACKOFF_START_MS)
   const reconnectTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+  const readyCountRef = useRef<number>(0)
 
   useEffect(() => {
     if (!productId) return
@@ -44,15 +53,22 @@ export function useBacklogRealtime(productId: string | null) {
 
       source.addEventListener('ready', () => {
         backoffRef.current = BACKOFF_START_MS
+        readyCountRef.current += 1
+        // T-862: eerste ready = initial connect; latere ready = reconnect.
+        if (readyCountRef.current > 1) {
+          void useProductWorkspaceStore
+            .getState()
+            .resyncActiveScopes('reconnect')
+        }
       })
 
       source.onmessage = (e) => {
         if (!e.data) return
         try {
           const payload = JSON.parse(e.data) as EntityPayload
-          useBacklogStore
+          useProductWorkspaceStore
             .getState()
-            .applyChange(payload.entity, payload.op, payload as Record<string, unknown>)
+            .applyRealtimeEvent(payload as unknown as ProductRealtimeEvent)
         } catch (err) {
           if (process.env.NODE_ENV !== 'production') {
             console.error('[realtime/backlog] failed to parse event', err, e.data)
@@ -70,23 +86,22 @@ export function useBacklogRealtime(productId: string | null) {
       }
     }
 
+    // T-861: stream blijft open op hidden. Reconnect alleen als source weg
+    // is (b.v. na netwerkfout) en de tab visible is.
     const onVisibility = () => {
-      if (document.visibilityState === 'hidden') {
+      if (document.visibilityState === 'visible' && sourceRef.current === null) {
-        close()
-      } else if (sourceRef.current === null) {
         backoffRef.current = BACKOFF_START_MS
         connect()
       }
     }
 
-    if (document.visibilityState === 'visible') {
+    connect()
-      connect()
-    }
     document.addEventListener('visibilitychange', onVisibility)
 
     return () => {
       document.removeEventListener('visibilitychange', onVisibility)
       close()
+      readyCountRef.current = 0
     }
   }, [productId])
 }

lib/realtime/use-notifications-realtime.ts

@@ -191,21 +191,30 @@ export function useNotificationsRealtime() {
       })
     }
 
+    // PBI-74: stream blijft open op hidden. Reconnect alleen als hij door
+    // netwerkfout/server-close weg is. Bij visible-overgang en bij online
+    // triggeren we router.refresh() zodat de notifications-bel verse state
+    // pakt — gemiste vraag-events via NOTIFY-throttling worden hierdoor
+    // alsnog zichtbaar.
     const onVisibilityChange = () => {
-      if (document.visibilityState === 'visible') {
+      if (document.visibilityState !== 'visible') return
-        if (!sourceRef.current || sourceRef.current.readyState === EventSource.CLOSED) {
+      if (!sourceRef.current || sourceRef.current.readyState === EventSource.CLOSED) {
-          connect()
+        connect()
-        }
-      } else {
-        close()
       }
+      router.refresh()
+    }
+
+    const onOnline = () => {
+      router.refresh()
     }
 
     connect()
     document.addEventListener('visibilitychange', onVisibilityChange)
+    window.addEventListener('online', onOnline)
 
     return () => {
       document.removeEventListener('visibilitychange', onVisibilityChange)
+      window.removeEventListener('online', onOnline)
       close()
     }
   }, [router])

lib/realtime/use-solo-realtime.ts

@@ -6,7 +6,12 @@
 // - Opent EventSource('/api/realtime/solo?product_id=...') wanneer
 //   productId niet null is; sluit de stream als productId null wordt.
 // - Reconnect met exponential backoff (1s → 30s, reset bij ready).
-// - Pauseert bij document.visibilityState === 'hidden', resumes bij visible.
+// - PBI-74: stream blijft open op tab hidden (geen close meer). Bij
+//   hidden→visible en bij window 'online' triggeren we router.refresh()
+//   zodat gemiste events alsnog binnenkomen via een verse server-render
+//   (re-fetcht initialTasks → initTasks reset solo-store). Postgres NOTIFY
+//   heeft geen replay, dus zonder deze resync zouden hidden-tab events
+//   permanent verloren zijn — zelfde fix als Story 5 voor backlog-realtime.
 // - Cleanup op unmount.
 // - Connection-status (status, showConnectingIndicator) wordt naar de
 //   solo-store geschreven; UI-componenten lezen daar uit.
@@ -19,6 +24,7 @@
 
 import { useEffect, useRef } from 'react'
 import { flushSync } from 'react-dom'
+import { useRouter } from 'next/navigation'
 import { useSoloStore } from '@/stores/solo-store'
 import type { ClaudeJobEvent, JobState, RealtimeEvent, RealtimeStatus } from '@/stores/solo-store'
 
@@ -27,10 +33,12 @@ const BACKOFF_MAX_MS = 30_000
 const CONNECTING_INDICATOR_DELAY_MS = 4_000
 
 export function useSoloRealtime(productId: string | null) {
+  const router = useRouter()
   const sourceRef = useRef<EventSource | null>(null)
   const backoffRef = useRef<number>(BACKOFF_START_MS)
   const reconnectTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
   const indicatorTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+  const readyCountRef = useRef<number>(0)
 
   useEffect(() => {
     const setStatus = useSoloStore.getState().setRealtimeStatus
@@ -88,6 +96,12 @@ export function useSoloRealtime(productId: string | null) {
       source.addEventListener('ready', () => {
         backoffRef.current = BACKOFF_START_MS
         scheduleIndicator('open')
+        readyCountRef.current += 1
+        // PBI-74: latere ready = post-reconnect → resync via router.refresh()
+        // zodat gemiste tasks-state via re-render initial-prop binnenkomt.
+        if (readyCountRef.current > 1) {
+          router.refresh()
+        }
       })
 
       source.addEventListener('claude_jobs_initial', (e) => {
@@ -173,25 +187,33 @@ export function useSoloRealtime(productId: string | null) {
       }
     }
 
+    // PBI-74: stream blijft open op hidden. Reconnect alleen als de stream
+    // door netwerkfout/server-close weg is en de tab visible is. Bij iedere
+    // visible-overgang triggeren we router.refresh() — gemiste events tijdens
+    // throttling/freeze worden via een verse server-render alsnog opgepakt.
     const onVisibility = () => {
-      if (document.visibilityState === 'hidden') {
+      if (document.visibilityState !== 'visible') return
-        close()
+      if (sourceRef.current === null) {
-        scheduleIndicator('disconnected')
-      } else if (sourceRef.current === null) {
         backoffRef.current = BACKOFF_START_MS
         connect()
       }
+      router.refresh()
     }
 
-    if (document.visibilityState === 'visible') {
+    const onOnline = () => {
-      connect()
+      router.refresh()
     }
+
+    connect()
     document.addEventListener('visibilitychange', onVisibility)
+    window.addEventListener('online', onOnline)
 
     return () => {
       document.removeEventListener('visibilitychange', onVisibility)
+      window.removeEventListener('online', onOnline)
       if (indicatorTimerRef.current) clearTimeout(indicatorTimerRef.current)
       close()
+      readyCountRef.current = 0
     }
-  }, [productId])
+  }, [productId, router])
 }

lib/realtime/use-workspace-resync.ts

@@ -0,0 +1,40 @@
+'use client'
+
+// PBI-74 / T-863: useWorkspaceResync hook.
+//
+// Trigger resyncActiveScopes bij:
+// - hidden→visible (browser-throttled events kunnen gemist zijn)
+// - online (netwerk hersteld na disconnect)
+//
+// Hoort gemount te worden naast useBacklogRealtime in BacklogHydrationWrapper.
+
+import { useEffect } from 'react'
+import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
+
+export function useWorkspaceResync(): void {
+  useEffect(() => {
+    if (typeof document === 'undefined') return
+
+    const onVisibility = () => {
+      if (document.visibilityState === 'visible') {
+        void useProductWorkspaceStore
+          .getState()
+          .resyncActiveScopes('visible')
+      }
+    }
+
+    const onOnline = () => {
+      void useProductWorkspaceStore
+        .getState()
+        .resyncActiveScopes('reconnect')
+    }
+
+    document.addEventListener('visibilitychange', onVisibility)
+    window.addEventListener('online', onOnline)
+
+    return () => {
+      document.removeEventListener('visibilitychange', onVisibility)
+      window.removeEventListener('online', onOnline)
+    }
+  }, [])
+}

stores/backlog-store.ts

@@ -1,143 +0,0 @@
-import { create } from 'zustand'
-import type { PbiStatusApi } from '@/lib/task-status'
-
-export interface BacklogPbi {
-  id: string
-  code: string | null
-  title: string
-  priority: number
-  description?: string | null
-  created_at: Date
-  status: PbiStatusApi
-}
-
-export interface BacklogStory {
-  id: string
-  code: string | null
-  title: string
-  description: string | null
-  acceptance_criteria: string | null
-  priority: number
-  status: string
-  pbi_id: string
-  sprint_id: string | null
-  created_at: Date
-}
-
-export interface BacklogTask {
-  id: string
-  title: string
-  description: string | null
-  priority: number
-  status: string
-  sort_order: number
-  story_id: string
-  created_at: Date
-}
-
-type Entity = 'pbi' | 'story' | 'task'
-type Op = 'I' | 'U' | 'D'
-
-interface InitialData {
-  pbis: BacklogPbi[]
-  storiesByPbi: Record<string, BacklogStory[]>
-  tasksByStory: Record<string, BacklogTask[]>
-}
-
-interface BacklogStore extends InitialData {
-  setInitialData: (data: InitialData) => void
-  applyChange: (entity: Entity, op: Op, data: Record<string, unknown>) => void
-}
-
-export const useBacklogStore = create<BacklogStore>((set) => ({
-  pbis: [],
-  storiesByPbi: {},
-  tasksByStory: {},
-
-  setInitialData: (data) => set(data),
-
-  applyChange: (entity, op, data) =>
-    set((state) => {
-      if (entity === 'pbi') {
-        const id = data.id as string
-        if (op === 'D') {
-          return { pbis: state.pbis.filter((p) => p.id !== id) }
-        }
-        if (op === 'U') {
-          return {
-            pbis: state.pbis.map((p) =>
-              p.id === id ? { ...p, ...(data as Partial<BacklogPbi>) } : p
-            ),
-          }
-        }
-        // I — idempotent: skip if already present (optimistic update may have arrived first)
-        if (state.pbis.some((p) => p.id === id)) return {}
-        return { pbis: [...state.pbis, data as unknown as BacklogPbi] }
-      }
-
-      if (entity === 'story') {
-        const id = data.id as string
-        if (op === 'D') {
-          const storiesByPbi = { ...state.storiesByPbi }
-          for (const pbiId of Object.keys(storiesByPbi)) {
-            storiesByPbi[pbiId] = storiesByPbi[pbiId].filter((s) => s.id !== id)
-          }
-          return { storiesByPbi }
-        }
-        if (op === 'U') {
-          const storiesByPbi = { ...state.storiesByPbi }
-          for (const pbiId of Object.keys(storiesByPbi)) {
-            const idx = storiesByPbi[pbiId].findIndex((s) => s.id === id)
-            if (idx !== -1) {
-              storiesByPbi[pbiId] = storiesByPbi[pbiId].map((s) =>
-                s.id === id ? { ...s, ...(data as Partial<BacklogStory>) } : s
-              )
-              break
-            }
-          }
-          return { storiesByPbi }
-        }
-        // I — idempotent: skip if already present
-        const pbiId = data.pbi_id as string
-        if ((state.storiesByPbi[pbiId] ?? []).some((s) => s.id === id)) return {}
-        return {
-          storiesByPbi: {
-            ...state.storiesByPbi,
-            [pbiId]: [...(state.storiesByPbi[pbiId] ?? []), data as unknown as BacklogStory],
-          },
-        }
-      }
-
-      // task
-      const id = data.id as string
-      if (op === 'D') {
-        const tasksByStory = { ...state.tasksByStory }
-        for (const storyId of Object.keys(tasksByStory)) {
-          tasksByStory[storyId] = tasksByStory[storyId].filter((t) => t.id !== id)
-        }
-        return { tasksByStory }
-      }
-      if (op === 'U') {
-        const tasksByStory = { ...state.tasksByStory }
-        for (const storyId of Object.keys(tasksByStory)) {
-          const idx = tasksByStory[storyId].findIndex((t) => t.id === id)
-          if (idx !== -1) {
-            tasksByStory[storyId] = tasksByStory[storyId].map((t) =>
-              t.id === id ? { ...t, ...(data as Partial<BacklogTask>) } : t
-            )
-            break
-          }
-        }
-        return { tasksByStory }
-      }
-      // I — idempotent: skip if already present
-      const storyId = data.story_id as string
-      if ((state.tasksByStory[storyId] ?? []).some((t) => t.id === id)) return {}
-      return {
-        tasksByStory: {
-          ...state.tasksByStory,
-          [storyId]: [...(state.tasksByStory[storyId] ?? []), data as unknown as BacklogTask],
-        },
-      }
-    }),
-}))

stores/planner-store.ts

@@ -1,46 +0,0 @@
-import { create } from 'zustand'
-
-interface PlannerStore {
-  // Order maps: productId → pbiId[]
-  pbiOrder: Record<string, string[]>
-  // Order maps: pbiId → storyId[]
-  storyOrder: Record<string, string[]>
-  // Priority maps: pbiId → priority
-  pbiPriority: Record<string, number>
-
-  initPbis: (productId: string, ids: string[]) => void
-  reorderPbis: (productId: string, ids: string[]) => void
-  rollbackPbis: (productId: string, ids: string[]) => void
-  updatePbiPriority: (pbiId: string, priority: number) => void
-
-  initStories: (pbiId: string, ids: string[]) => void
-  reorderStories: (pbiId: string, ids: string[]) => void
-  rollbackStories: (pbiId: string, ids: string[]) => void
-}
-
-export const usePlannerStore = create<PlannerStore>((set) => ({
-  pbiOrder: {},
-  storyOrder: {},
-  pbiPriority: {},
-
-  initPbis: (productId, ids) =>
-    set((state) => ({ pbiOrder: { ...state.pbiOrder, [productId]: ids } })),
-
-  reorderPbis: (productId, ids) =>
-    set((state) => ({ pbiOrder: { ...state.pbiOrder, [productId]: ids } })),
-
-  rollbackPbis: (productId, ids) =>
-    set((state) => ({ pbiOrder: { ...state.pbiOrder, [productId]: ids } })),
-
-  updatePbiPriority: (pbiId, priority) =>
-    set((state) => ({ pbiPriority: { ...state.pbiPriority, [pbiId]: priority } })),
-
-  initStories: (pbiId, ids) =>
-    set((state) => ({ storyOrder: { ...state.storyOrder, [pbiId]: ids } })),
-
-  reorderStories: (pbiId, ids) =>
-    set((state) => ({ storyOrder: { ...state.storyOrder, [pbiId]: ids } })),
-
-  rollbackStories: (pbiId, ids) =>
-    set((state) => ({ storyOrder: { ...state.storyOrder, [pbiId]: ids } })),
-}))

stores/product-store.ts

@@ -1,13 +0,0 @@
-import { create } from 'zustand'
-
-interface ProductStore {
-  currentProduct: { id: string; name: string } | null
-  setCurrentProduct: (id: string, name: string) => void
-  clearCurrentProduct: () => void
-}
-
-export const useProductStore = create<ProductStore>((set) => ({
-  currentProduct: null,
-  setCurrentProduct: (id, name) => set({ currentProduct: { id, name } }),
-  clearCurrentProduct: () => set({ currentProduct: null }),
-}))

stores/product-workspace/restore.ts

@@ -0,0 +1,110 @@
+const STORAGE_KEY = 'product-workspace-hints'
+
+interface PerProductHint {
+  lastActivePbiId?: string | null
+  lastActiveStoryId?: string | null
+  lastActiveTaskId?: string | null
+}
+
+export interface WorkspaceHints {
+  lastActiveProductId: string | null
+  perProduct: Record<string, PerProductHint>
+}
+
+const EMPTY_HINTS: WorkspaceHints = {
+  lastActiveProductId: null,
+  perProduct: {},
+}
+
+function safeStorage(): Storage | null {
+  if (typeof globalThis === 'undefined') return null
+  try {
+    const ls = (globalThis as { localStorage?: Storage }).localStorage
+    return ls ?? null
+  } catch {
+    return null
+  }
+}
+
+export function readHints(): WorkspaceHints {
+  const storage = safeStorage()
+  if (!storage) return { ...EMPTY_HINTS, perProduct: {} }
+  try {
+    const raw = storage.getItem(STORAGE_KEY)
+    if (!raw) return { ...EMPTY_HINTS, perProduct: {} }
+    const parsed = JSON.parse(raw) as Partial<WorkspaceHints> | null
+    if (!parsed || typeof parsed !== 'object') {
+      return { ...EMPTY_HINTS, perProduct: {} }
+    }
+    return {
+      lastActiveProductId: parsed.lastActiveProductId ?? null,
+      perProduct:
+        parsed.perProduct && typeof parsed.perProduct === 'object'
+          ? parsed.perProduct
+          : {},
+    }
+  } catch {
+    return { ...EMPTY_HINTS, perProduct: {} }
+  }
+}
+
+function writeHints(hints: WorkspaceHints): void {
+  const storage = safeStorage()
+  if (!storage) return
+  try {
+    storage.setItem(STORAGE_KEY, JSON.stringify(hints))
+  } catch {
+    // ignore quota or serialization errors
+  }
+}
+
+export function writeProductHint(productId: string | null): void {
+  const hints = readHints()
+  hints.lastActiveProductId = productId
+  writeHints(hints)
+}
+
+function ensurePerProduct(hints: WorkspaceHints, productId: string): PerProductHint {
+  if (!hints.perProduct[productId]) {
+    hints.perProduct[productId] = {}
+  }
+  return hints.perProduct[productId]
+}
+
+export function writePbiHint(productId: string, pbiId: string | null): void {
+  const hints = readHints()
+  const entry = ensurePerProduct(hints, productId)
+  entry.lastActivePbiId = pbiId
+  if (pbiId === null) {
+    entry.lastActiveStoryId = null
+    entry.lastActiveTaskId = null
+  }
+  writeHints(hints)
+}
+
+export function writeStoryHint(productId: string, storyId: string | null): void {
+  const hints = readHints()
+  const entry = ensurePerProduct(hints, productId)
+  entry.lastActiveStoryId = storyId
+  if (storyId === null) {
+    entry.lastActiveTaskId = null
+  }
+  writeHints(hints)
+}
+
+export function writeTaskHint(productId: string, taskId: string | null): void {
+  const hints = readHints()
+  const entry = ensurePerProduct(hints, productId)
+  entry.lastActiveTaskId = taskId
+  writeHints(hints)
+}
+
+export function clearHints(): void {
+  const storage = safeStorage()
+  if (!storage) return
+  try {
+    storage.removeItem(STORAGE_KEY)
+  } catch {
+    // ignore
+  }
+}

stores/product-workspace/selectors.ts

@@ -0,0 +1,102 @@
+import type { ProductWorkspaceStore } from './store'
+import type { BacklogPbi, BacklogStory, BacklogTask, TaskDetail } from './types'
+
+// G1: stable EMPTY-references zodat selectors geen nieuwe array per call retourneren.
+const EMPTY_PBIS: BacklogPbi[] = []
+const EMPTY_STORIES: BacklogStory[] = []
+const EMPTY_TASKS: (BacklogTask | TaskDetail)[] = []
+
+/**
+ * Lijst-selector. Vereist `useShallow` in componenten (G2) — anders re-rendert
+ * elke ongerelateerde store-mutatie het component.
+ */
+export function selectVisiblePbis(s: ProductWorkspaceStore): BacklogPbi[] {
+  if (s.relations.pbiIds.length === 0) return EMPTY_PBIS
+  const out: BacklogPbi[] = []
+  for (const id of s.relations.pbiIds) {
+    const pbi = s.entities.pbisById[id]
+    if (pbi) out.push(pbi)
+  }
+  return out.length === 0 ? EMPTY_PBIS : out
+}
+
+/**
+ * Lijst-selector. Vereist `useShallow` in componenten (G2).
+ */
+export function selectStoriesForActivePbi(s: ProductWorkspaceStore): BacklogStory[] {
+  const pbiId = s.context.activePbiId
+  if (!pbiId) return EMPTY_STORIES
+  const ids = s.relations.storyIdsByPbi[pbiId]
+  if (!ids || ids.length === 0) return EMPTY_STORIES
+  const out: BacklogStory[] = []
+  for (const id of ids) {
+    const story = s.entities.storiesById[id]
+    if (story) out.push(story)
+  }
+  return out.length === 0 ? EMPTY_STORIES : out
+}
+
+/**
+ * Lijst-selector. Vereist `useShallow` in componenten (G2).
+ */
+export function selectTasksForActiveStory(
+  s: ProductWorkspaceStore,
+): (BacklogTask | TaskDetail)[] {
+  const storyId = s.context.activeStoryId
+  if (!storyId) return EMPTY_TASKS
+  const ids = s.relations.taskIdsByStory[storyId]
+  if (!ids || ids.length === 0) return EMPTY_TASKS
+  const out: (BacklogTask | TaskDetail)[] = []
+  for (const id of ids) {
+    const task = s.entities.tasksById[id]
+    if (task) out.push(task)
+  }
+  return out.length === 0 ? EMPTY_TASKS : out
+}
+
+/**
+ * Single-value selector. `useShallow` niet vereist — retourneert stable
+ * entity-reference (zelfde object zolang entity ongewijzigd).
+ */
+export function selectActivePbi(s: ProductWorkspaceStore): BacklogPbi | null {
+  const id = s.context.activePbiId
+  if (!id) return null
+  return s.entities.pbisById[id] ?? null
+}
+
+/**
+ * Single-value selector. `useShallow` niet vereist.
+ */
+export function selectActiveStory(s: ProductWorkspaceStore): BacklogStory | null {
+  const id = s.context.activeStoryId
+  if (!id) return null
+  return s.entities.storiesById[id] ?? null
+}
+
+/**
+ * Single-value selector. `useShallow` niet vereist.
+ */
+export function selectActiveTask(
+  s: ProductWorkspaceStore,
+): BacklogTask | TaskDetail | null {
+  const id = s.context.activeTaskId
+  if (!id) return null
+  return s.entities.tasksById[id] ?? null
+}
+
+/**
+ * Single-value selector voor stories binnen een specifiek PBI (niet per se actief).
+ */
+export function selectStoriesForPbi(
+  s: ProductWorkspaceStore,
+  pbiId: string,
+): BacklogStory[] {
+  const ids = s.relations.storyIdsByPbi[pbiId]
+  if (!ids || ids.length === 0) return EMPTY_STORIES
+  const out: BacklogStory[] = []
+  for (const id of ids) {
+    const story = s.entities.storiesById[id]
+    if (story) out.push(story)
+  }
+  return out.length === 0 ? EMPTY_STORIES : out
+}

stores/product-workspace/store.ts

@@ -0,0 +1,841 @@
+import { create } from 'zustand'
+import { immer } from 'zustand/middleware/immer'
+
+import {
+  isDetail,
+  type ActiveProduct,
+  type BacklogPbi,
+  type BacklogStory,
+  type BacklogTask,
+  type OptimisticMutation,
+  type PendingOptimisticMutation,
+  type ProductBacklogSnapshot,
+  type ProductRealtimeEvent,
+  type RealtimeStatus,
+  type ResyncReason,
+  type TaskDetail,
+} from './types'
+import {
+  readHints,
+  writePbiHint,
+  writeProductHint,
+  writeStoryHint,
+  writeTaskHint,
+} from './restore'
+
+interface ContextSlice {
+  activeProduct: ActiveProduct | null
+  activePbiId: string | null
+  activeStoryId: string | null
+  activeTaskId: string | null
+}
+
+interface EntitiesSlice {
+  pbisById: Record<string, BacklogPbi>
+  storiesById: Record<string, BacklogStory>
+  tasksById: Record<string, BacklogTask | TaskDetail>
+}
+
+interface RelationsSlice {
+  pbiIds: string[]
+  storyIdsByPbi: Record<string, string[]>
+  taskIdsByStory: Record<string, string[]>
+}
+
+interface LoadingSlice {
+  loadedProductId: string | null
+  loadingProductId: string | null
+  loadedPbiIds: Record<string, true>
+  loadedStoryIds: Record<string, true>
+  loadedTaskIds: Record<string, true>
+  activeRequestId: string | null
+}
+
+interface SyncSlice {
+  realtimeStatus: RealtimeStatus
+  lastEventAt: number | null
+  lastResyncAt: number | null
+  resyncReason: ResyncReason | null
+}
+
+interface State {
+  context: ContextSlice
+  entities: EntitiesSlice
+  relations: RelationsSlice
+  loading: LoadingSlice
+  sync: SyncSlice
+  pendingMutations: Record<string, PendingOptimisticMutation>
+}
+
+interface Actions {
+  hydrateSnapshot(snapshot: ProductBacklogSnapshot): void
+
+  setActiveProduct(product: ActiveProduct | null): void
+  setActivePbi(pbiId: string | null): void
+  setActiveStory(storyId: string | null): void
+  setActiveTask(taskId: string | null): void
+
+  ensureProductLoaded(productId: string, requestId?: string): Promise<void>
+  ensurePbiLoaded(pbiId: string, requestId?: string): Promise<void>
+  ensureStoryLoaded(storyId: string, requestId?: string): Promise<void>
+  ensureTaskLoaded(taskId: string, requestId?: string): Promise<void>
+
+  applyRealtimeEvent(event: ProductRealtimeEvent | Record<string, unknown>): void
+  resyncActiveScopes(reason: ResyncReason): Promise<void>
+  resyncLoadedScopes(reason: ResyncReason): Promise<void>
+
+  applyOptimisticMutation(mutation: OptimisticMutation): string
+  rollbackMutation(mutationId: string): void
+  settleMutation(mutationId: string): void
+
+  setRealtimeStatus(status: RealtimeStatus): void
+}
+
+export type ProductWorkspaceStore = State & Actions
+
+const initialState: State = {
+  context: {
+    activeProduct: null,
+    activePbiId: null,
+    activeStoryId: null,
+    activeTaskId: null,
+  },
+  entities: {
+    pbisById: {},
+    storiesById: {},
+    tasksById: {},
+  },
+  relations: {
+    pbiIds: [],
+    storyIdsByPbi: {},
+    taskIdsByStory: {},
+  },
+  loading: {
+    loadedProductId: null,
+    loadingProductId: null,
+    loadedPbiIds: {},
+    loadedStoryIds: {},
+    loadedTaskIds: {},
+    activeRequestId: null,
+  },
+  sync: {
+    realtimeStatus: 'connecting',
+    lastEventAt: null,
+    lastResyncAt: null,
+    resyncReason: null,
+  },
+  pendingMutations: {},
+}
+
+function comparePbi(a: BacklogPbi, b: BacklogPbi): number {
+  if (a.priority !== b.priority) return a.priority - b.priority
+  if (a.sort_order !== b.sort_order) return a.sort_order - b.sort_order
+  return new Date(a.created_at).getTime() - new Date(b.created_at).getTime()
+}
+
+function compareStory(a: BacklogStory, b: BacklogStory): number {
+  if (a.priority !== b.priority) return a.priority - b.priority
+  if (a.sort_order !== b.sort_order) return a.sort_order - b.sort_order
+  return new Date(a.created_at).getTime() - new Date(b.created_at).getTime()
+}
+
+function compareTask(a: BacklogTask, b: BacklogTask): number {
+  if (a.sort_order !== b.sort_order) return a.sort_order - b.sort_order
+  return new Date(a.created_at).getTime() - new Date(b.created_at).getTime()
+}
+
+function newRequestId(): string {
+  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
+    return crypto.randomUUID()
+  }
+  return `${Date.now()}-${Math.random().toString(36).slice(2)}`
+}
+
+function isKnownEntity(entity: unknown): entity is 'pbi' | 'story' | 'task' {
+  return entity === 'pbi' || entity === 'story' || entity === 'task'
+}
+
+function isUnknownEntityEvent(p: Record<string, unknown>): boolean {
+  if (typeof p.entity !== 'string') return false
+  if (isKnownEntity(p.entity)) return false
+  if ('type' in p) return false
+  return true
+}
+
+async function fetchJson<T>(url: string, init?: RequestInit): Promise<T> {
+  const response = await fetch(url, { cache: 'no-store', ...init })
+  if (!response.ok) {
+    throw new Error(`Fetch ${url} failed with ${response.status}`)
+  }
+  return (await response.json()) as T
+}
+
+export const useProductWorkspaceStore = create<ProductWorkspaceStore>()(
+  immer((set, get) => ({
+    ...initialState,
+
+    hydrateSnapshot(snapshot) {
+      set((s) => {
+        if (snapshot.product) s.context.activeProduct = snapshot.product
+
+        s.entities.pbisById = {}
+        s.entities.storiesById = {}
+        s.entities.tasksById = {}
+        s.relations.pbiIds = []
+        s.relations.storyIdsByPbi = {}
+        s.relations.taskIdsByStory = {}
+
+        for (const pbi of snapshot.pbis) {
+          s.entities.pbisById[pbi.id] = pbi
+        }
+        s.relations.pbiIds = [...snapshot.pbis].sort(comparePbi).map((p) => p.id)
+
+        for (const [pbiId, stories] of Object.entries(snapshot.storiesByPbi)) {
+          for (const story of stories) {
+            s.entities.storiesById[story.id] = story
+          }
+          s.relations.storyIdsByPbi[pbiId] = [...stories]
+            .sort(compareStory)
+            .map((st) => st.id)
+        }
+
+        for (const [storyId, tasks] of Object.entries(snapshot.tasksByStory)) {
+          for (const task of tasks) {
+            s.entities.tasksById[task.id] = task
+          }
+          s.relations.taskIdsByStory[storyId] = [...tasks]
+            .sort(compareTask)
+            .map((t) => t.id)
+        }
+
+        if (snapshot.product) {
+          s.loading.loadedProductId = snapshot.product.id
+        }
+      })
+    },
+
+    setActiveProduct(product) {
+      const requestId = newRequestId()
+      const productChanged = get().context.activeProduct?.id !== product?.id
+
+      set((s) => {
+        s.context.activeProduct = product
+        s.context.activePbiId = null
+        s.context.activeStoryId = null
+        s.context.activeTaskId = null
+        s.loading.activeRequestId = requestId
+
+        if (productChanged) {
+          s.entities.pbisById = {}
+          s.entities.storiesById = {}
+          s.entities.tasksById = {}
+          s.relations.pbiIds = []
+          s.relations.storyIdsByPbi = {}
+          s.relations.taskIdsByStory = {}
+          s.loading.loadedProductId = null
+          s.loading.loadedPbiIds = {}
+          s.loading.loadedStoryIds = {}
+          s.loading.loadedTaskIds = {}
+        }
+      })
+
+      // T-858: persisteer product-hint zodat een volgende cold reload deze
+      // selectie kan herstellen. T-857: restore-flow start na ensureProductLoaded.
+      writeProductHint(product?.id ?? null)
+
+      if (product) {
+        const productId = product.id
+        void (async () => {
+          await get().ensureProductLoaded(productId, requestId)
+          if (get().loading.activeRequestId !== requestId) return
+          // T-857: cascade-restore — alleen toepassen als hint-id nog in
+          // entities zit (entiteit accessible).
+          const hint = readHints().perProduct[productId]?.lastActivePbiId
+          if (hint && get().entities.pbisById[hint]) {
+            get().setActivePbi(hint)
+          }
+        })()
+      }
+    },
+
+    setActivePbi(pbiId) {
+      const requestId = newRequestId()
+      const productId = get().context.activeProduct?.id ?? null
+
+      set((s) => {
+        s.context.activePbiId = pbiId
+        s.context.activeStoryId = null
+        s.context.activeTaskId = null
+        s.loading.activeRequestId = requestId
+      })
+
+      // T-858: persisteer pbi-hint per product. null wist child-hints (zie
+      // restore.ts writePbiHint).
+      if (productId) writePbiHint(productId, pbiId)
+
+      if (pbiId) {
+        void (async () => {
+          await get().ensurePbiLoaded(pbiId, requestId)
+          if (get().loading.activeRequestId !== requestId) return
+          if (!productId) return
+          // T-857: cascade-restore
+          const hint = readHints().perProduct[productId]?.lastActiveStoryId
+          if (hint && get().entities.storiesById[hint]) {
+            get().setActiveStory(hint)
+          }
+        })()
+      }
+    },
+
+    setActiveStory(storyId) {
+      const requestId = newRequestId()
+      const productId = get().context.activeProduct?.id ?? null
+
+      set((s) => {
+        s.context.activeStoryId = storyId
+        s.context.activeTaskId = null
+        s.loading.activeRequestId = requestId
+      })
+
+      if (productId) writeStoryHint(productId, storyId)
+
+      if (storyId) {
+        void (async () => {
+          await get().ensureStoryLoaded(storyId, requestId)
+          if (get().loading.activeRequestId !== requestId) return
+          if (!productId) return
+          const hint = readHints().perProduct[productId]?.lastActiveTaskId
+          if (hint && get().entities.tasksById[hint]) {
+            get().setActiveTask(hint)
+          }
+        })()
+      }
+    },
+
+    setActiveTask(taskId) {
+      const productId = get().context.activeProduct?.id ?? null
+
+      set((s) => {
+        s.context.activeTaskId = taskId
+      })
+
+      if (productId) writeTaskHint(productId, taskId)
+
+      if (taskId) {
+        void get().ensureTaskLoaded(taskId)
+      }
+    },
+
+    async ensureProductLoaded(productId, requestId) {
+      set((s) => {
+        s.loading.loadingProductId = productId
+      })
+      try {
+        const snapshot = await fetchJson<ProductBacklogSnapshot | null>(
+          `/api/products/${encodeURIComponent(productId)}/backlog`,
+        )
+        if (requestId && get().loading.activeRequestId !== requestId) return
+        if (!snapshot || !Array.isArray(snapshot.pbis)) return
+        get().hydrateSnapshot(snapshot)
+        set((s) => {
+          s.loading.loadedProductId = productId
+          for (const pbi of snapshot.pbis) {
+            s.loading.loadedPbiIds[pbi.id] = true
+          }
+        })
+      } finally {
+        set((s) => {
+          if (s.loading.loadingProductId === productId) {
+            s.loading.loadingProductId = null
+          }
+        })
+      }
+    },
+
+    async ensurePbiLoaded(pbiId, requestId) {
+      const stories = await fetchJson<BacklogStory[] | null>(
+        `/api/pbis/${encodeURIComponent(pbiId)}/stories`,
+      )
+      if (requestId && get().loading.activeRequestId !== requestId) return
+      if (!Array.isArray(stories)) return
+      set((s) => {
+        for (const story of stories) {
+          s.entities.storiesById[story.id] = story
+        }
+        s.relations.storyIdsByPbi[pbiId] = [...stories]
+          .sort(compareStory)
+          .map((st) => st.id)
+        s.loading.loadedPbiIds[pbiId] = true
+      })
+    },
+
+    async ensureStoryLoaded(storyId, requestId) {
+      const tasks = await fetchJson<BacklogTask[] | null>(
+        `/api/stories/${encodeURIComponent(storyId)}/tasks`,
+      )
+      if (requestId && get().loading.activeRequestId !== requestId) return
+      if (!Array.isArray(tasks)) return
+      set((s) => {
+        for (const task of tasks) {
+          const existing = s.entities.tasksById[task.id]
+          if (existing && isDetail(existing)) {
+            s.entities.tasksById[task.id] = { ...existing, ...task }
+          } else {
+            s.entities.tasksById[task.id] = task
+          }
+        }
+        s.relations.taskIdsByStory[storyId] = [...tasks]
+          .sort(compareTask)
+          .map((t) => t.id)
+        s.loading.loadedStoryIds[storyId] = true
+      })
+    },
+
+    async ensureTaskLoaded(taskId, requestId) {
+      const detail = await fetchJson<TaskDetail | null>(
+        `/api/tasks/${encodeURIComponent(taskId)}`,
+      )
+      if (requestId && get().loading.activeRequestId !== requestId) return
+      if (!detail || typeof detail !== 'object') return
+      set((s) => {
+        s.entities.tasksById[taskId] = { ...detail, _detail: true }
+        s.loading.loadedTaskIds[taskId] = true
+      })
+    },
+
+    applyRealtimeEvent(event) {
+      const payload = event as Record<string, unknown>
+      const activeProductId = get().context.activeProduct?.id ?? null
+
+      set((s) => {
+        s.sync.lastEventAt = Date.now()
+      })
+
+      if (
+        typeof payload.product_id === 'string' &&
+        activeProductId &&
+        payload.product_id !== activeProductId
+      ) {
+        return
+      }
+
+      if (isUnknownEntityEvent(payload)) {
+        if (payload.product_id === activeProductId) {
+          void get().resyncActiveScopes('unknown-event')
+        }
+        return
+      }
+
+      const entity = payload.entity
+      const op = payload.op
+      if (!isKnownEntity(entity)) return
+      if (op !== 'I' && op !== 'U' && op !== 'D') return
+
+      const id = payload.id
+      if (typeof id !== 'string') return
+
+      if (entity === 'pbi') {
+        applyPbiEvent(id, op, payload, set, get)
+      } else if (entity === 'story') {
+        applyStoryEvent(id, op, payload, set, get)
+      } else if (entity === 'task') {
+        applyTaskEvent(id, op, payload, set, get)
+      }
+    },
+
+    async resyncActiveScopes(reason) {
+      const ctx = get().context
+      const tasks: Promise<void>[] = []
+      if (ctx.activeProduct?.id) {
+        tasks.push(get().ensureProductLoaded(ctx.activeProduct.id))
+      }
+      if (ctx.activePbiId) tasks.push(get().ensurePbiLoaded(ctx.activePbiId))
+      if (ctx.activeStoryId) tasks.push(get().ensureStoryLoaded(ctx.activeStoryId))
+      if (ctx.activeTaskId) tasks.push(get().ensureTaskLoaded(ctx.activeTaskId))
+      set((s) => {
+        s.sync.lastResyncAt = Date.now()
+        s.sync.resyncReason = reason
+      })
+      await Promise.allSettled(tasks)
+    },
+
+    async resyncLoadedScopes(reason) {
+      const loading = get().loading
+      const tasks: Promise<void>[] = []
+      if (loading.loadedProductId) {
+        tasks.push(get().ensureProductLoaded(loading.loadedProductId))
+      }
+      for (const pbiId of Object.keys(loading.loadedPbiIds)) {
+        tasks.push(get().ensurePbiLoaded(pbiId))
+      }
+      for (const storyId of Object.keys(loading.loadedStoryIds)) {
+        tasks.push(get().ensureStoryLoaded(storyId))
+      }
+      for (const taskId of Object.keys(loading.loadedTaskIds)) {
+        tasks.push(get().ensureTaskLoaded(taskId))
+      }
+      set((s) => {
+        s.sync.lastResyncAt = Date.now()
+        s.sync.resyncReason = reason
+      })
+      await Promise.allSettled(tasks)
+    },
+
+    applyOptimisticMutation(mutation) {
+      const id = newRequestId()
+      set((s) => {
+        s.pendingMutations[id] = {
+          id,
+          mutation,
+          createdAt: Date.now(),
+        }
+        switch (mutation.kind) {
+          case 'pbi-order':
+            // store-call passes new order via separate set, snapshot is prevPbiIds
+            break
+          case 'story-order':
+            break
+          case 'task-order':
+            break
+          case 'entity-patch':
+            break
+        }
+      })
+      return id
+    },
+
+    rollbackMutation(mutationId) {
+      const pending = get().pendingMutations[mutationId]
+      if (!pending) return
+      const { mutation } = pending
+      set((s) => {
+        switch (mutation.kind) {
+          case 'pbi-order':
+            s.relations.pbiIds = [...mutation.prevPbiIds]
+            break
+          case 'story-order':
+            s.relations.storyIdsByPbi[mutation.pbiId] = [...mutation.prevStoryIds]
+            break
+          case 'task-order':
+            s.relations.taskIdsByStory[mutation.storyId] = [...mutation.prevTaskIds]
+            break
+          case 'entity-patch': {
+            const { entity, id, prev } = mutation
+            if (prev) {
+              if (entity === 'pbi') s.entities.pbisById[id] = prev as BacklogPbi
+              else if (entity === 'story') s.entities.storiesById[id] = prev as BacklogStory
+              else s.entities.tasksById[id] = prev as BacklogTask | TaskDetail
+            } else {
+              if (entity === 'pbi') delete s.entities.pbisById[id]
+              else if (entity === 'story') delete s.entities.storiesById[id]
+              else delete s.entities.tasksById[id]
+            }
+            break
+          }
+        }
+        delete s.pendingMutations[mutationId]
+      })
+    },
+
+    settleMutation(mutationId) {
+      set((s) => {
+        delete s.pendingMutations[mutationId]
+      })
+    },
+
+    setRealtimeStatus(status) {
+      set((s) => {
+        s.sync.realtimeStatus = status
+      })
+    },
+  })),
+)
+
+type ImmerSet = Parameters<Parameters<typeof immer<ProductWorkspaceStore>>[0]>[0]
+type ImmerGet = () => ProductWorkspaceStore
+
+function applyPbiEvent(
+  id: string,
+  op: 'I' | 'U' | 'D',
+  payload: Record<string, unknown>,
+  set: ImmerSet,
+  get: ImmerGet,
+) {
+  if (op === 'D') {
+    set((s) => {
+      const childStoryIds = s.relations.storyIdsByPbi[id] ?? []
+      for (const sid of childStoryIds) {
+        const childTaskIds = s.relations.taskIdsByStory[sid] ?? []
+        for (const tid of childTaskIds) {
+          delete s.entities.tasksById[tid]
+        }
+        delete s.relations.taskIdsByStory[sid]
+        delete s.entities.storiesById[sid]
+      }
+      delete s.relations.storyIdsByPbi[id]
+      delete s.entities.pbisById[id]
+      s.relations.pbiIds = s.relations.pbiIds.filter((p) => p !== id)
+      if (s.context.activePbiId === id) {
+        s.context.activePbiId = null
+        s.context.activeStoryId = null
+        s.context.activeTaskId = null
+      }
+    })
+    return
+  }
+
+  if (op === 'U') {
+    if (!get().entities.pbisById[id]) return
+    set((s) => {
+      const existing = s.entities.pbisById[id]
+      if (!existing) return
+      Object.assign(existing, sanitizePbiPayload(payload))
+      s.relations.pbiIds = sortPbiIds(s.entities.pbisById, s.relations.pbiIds)
+    })
+    return
+  }
+
+  // I
+  if (get().entities.pbisById[id]) return
+  set((s) => {
+    const pbi = coercePbiPayload(id, payload)
+    s.entities.pbisById[id] = pbi
+    s.relations.pbiIds.push(id)
+    s.relations.pbiIds = sortPbiIds(s.entities.pbisById, s.relations.pbiIds)
+  })
+}
+
+function applyStoryEvent(
+  id: string,
+  op: 'I' | 'U' | 'D',
+  payload: Record<string, unknown>,
+  set: ImmerSet,
+  get: ImmerGet,
+) {
+  if (op === 'D') {
+    set((s) => {
+      const childTaskIds = s.relations.taskIdsByStory[id] ?? []
+      for (const tid of childTaskIds) {
+        delete s.entities.tasksById[tid]
+      }
+      delete s.relations.taskIdsByStory[id]
+      const story = s.entities.storiesById[id]
+      delete s.entities.storiesById[id]
+      if (story) {
+        const ids = s.relations.storyIdsByPbi[story.pbi_id]
+        if (ids) {
+          s.relations.storyIdsByPbi[story.pbi_id] = ids.filter((sid) => sid !== id)
+        }
+      } else {
+        for (const pbiId of Object.keys(s.relations.storyIdsByPbi)) {
+          s.relations.storyIdsByPbi[pbiId] = s.relations.storyIdsByPbi[pbiId].filter(
+            (sid) => sid !== id,
+          )
+        }
+      }
+      if (s.context.activeStoryId === id) {
+        s.context.activeStoryId = null
+        s.context.activeTaskId = null
+      }
+    })
+    return
+  }
+
+  if (op === 'U') {
+    const existing = get().entities.storiesById[id]
+    if (!existing) return
+    set((s) => {
+      const story = s.entities.storiesById[id]
+      if (!story) return
+      const oldPbiId = story.pbi_id
+      Object.assign(story, sanitizeStoryPayload(payload))
+      const newPbiId = story.pbi_id
+      if (oldPbiId !== newPbiId) {
+        const oldList = s.relations.storyIdsByPbi[oldPbiId]
+        if (oldList) {
+          s.relations.storyIdsByPbi[oldPbiId] = oldList.filter((sid) => sid !== id)
+        }
+        const targetList = s.relations.storyIdsByPbi[newPbiId] ?? []
+        if (!targetList.includes(id)) targetList.push(id)
+        s.relations.storyIdsByPbi[newPbiId] = sortStoryIds(s.entities.storiesById, targetList)
+      } else if (s.relations.storyIdsByPbi[oldPbiId]) {
+        s.relations.storyIdsByPbi[oldPbiId] = sortStoryIds(
+          s.entities.storiesById,
+          s.relations.storyIdsByPbi[oldPbiId],
+        )
+      }
+    })
+    return
+  }
+
+  // I
+  if (get().entities.storiesById[id]) return
+  set((s) => {
+    const story = coerceStoryPayload(id, payload)
+    s.entities.storiesById[id] = story
+    const list = s.relations.storyIdsByPbi[story.pbi_id] ?? []
+    list.push(id)
+    s.relations.storyIdsByPbi[story.pbi_id] = sortStoryIds(s.entities.storiesById, list)
+  })
+}
+
+function applyTaskEvent(
+  id: string,
+  op: 'I' | 'U' | 'D',
+  payload: Record<string, unknown>,
+  set: ImmerSet,
+  get: ImmerGet,
+) {
+  if (op === 'D') {
+    set((s) => {
+      const task = s.entities.tasksById[id]
+      delete s.entities.tasksById[id]
+      if (task) {
+        const ids = s.relations.taskIdsByStory[task.story_id]
+        if (ids) {
+          s.relations.taskIdsByStory[task.story_id] = ids.filter((tid) => tid !== id)
+        }
+      } else {
+        for (const storyId of Object.keys(s.relations.taskIdsByStory)) {
+          s.relations.taskIdsByStory[storyId] = s.relations.taskIdsByStory[storyId].filter(
+            (tid) => tid !== id,
+          )
+        }
+      }
+      if (s.context.activeTaskId === id) {
+        s.context.activeTaskId = null
+      }
+    })
+    return
+  }
+
+  if (op === 'U') {
+    const existing = get().entities.tasksById[id]
+    if (!existing) return
+    set((s) => {
+      const task = s.entities.tasksById[id]
+      if (!task) return
+      const oldStoryId = task.story_id
+      Object.assign(task, sanitizeTaskPayload(payload))
+      const newStoryId = task.story_id
+      if (oldStoryId !== newStoryId) {
+        const oldList = s.relations.taskIdsByStory[oldStoryId]
+        if (oldList) {
+          s.relations.taskIdsByStory[oldStoryId] = oldList.filter((tid) => tid !== id)
+        }
+        const targetList = s.relations.taskIdsByStory[newStoryId] ?? []
+        if (!targetList.includes(id)) targetList.push(id)
+        s.relations.taskIdsByStory[newStoryId] = sortTaskIds(s.entities.tasksById, targetList)
+      } else if (s.relations.taskIdsByStory[oldStoryId]) {
+        s.relations.taskIdsByStory[oldStoryId] = sortTaskIds(
+          s.entities.tasksById,
+          s.relations.taskIdsByStory[oldStoryId],
+        )
+      }
+    })
+    return
+  }
+
+  // I
+  if (get().entities.tasksById[id]) return
+  set((s) => {
+    const task = coerceTaskPayload(id, payload)
+    s.entities.tasksById[id] = task
+    const list = s.relations.taskIdsByStory[task.story_id] ?? []
+    list.push(id)
+    s.relations.taskIdsByStory[task.story_id] = sortTaskIds(s.entities.tasksById, list)
+  })
+}
+
+function sortPbiIds(byId: Record<string, BacklogPbi>, ids: string[]): string[] {
+  return [...new Set(ids)]
+    .filter((id) => byId[id] !== undefined)
+    .sort((a, b) => comparePbi(byId[a], byId[b]))
+}
+
+function sortStoryIds(byId: Record<string, BacklogStory>, ids: string[]): string[] {
+  return [...new Set(ids)]
+    .filter((id) => byId[id] !== undefined)
+    .sort((a, b) => compareStory(byId[a], byId[b]))
+}
+
+function sortTaskIds(
+  byId: Record<string, BacklogTask | TaskDetail>,
+  ids: string[],
+): string[] {
+  return [...new Set(ids)]
+    .filter((id) => byId[id] !== undefined)
+    .sort((a, b) => compareTask(byId[a], byId[b]))
+}
+
+function sanitizePbiPayload(p: Record<string, unknown>): Partial<BacklogPbi> {
+  const { entity: _e, op: _o, ...rest } = p
+  void _e
+  void _o
+  return rest as Partial<BacklogPbi>
+}
+
+function sanitizeStoryPayload(p: Record<string, unknown>): Partial<BacklogStory> {
+  const { entity: _e, op: _o, ...rest } = p
+  void _e
+  void _o
+  return rest as Partial<BacklogStory>
+}
+
+function sanitizeTaskPayload(p: Record<string, unknown>): Partial<BacklogTask> {
+  const { entity: _e, op: _o, ...rest } = p
+  void _e
+  void _o
+  return rest as Partial<BacklogTask>
+}
+
+function coercePbiPayload(id: string, p: Record<string, unknown>): BacklogPbi {
+  return {
+    id,
+    code: (p.code as string | null) ?? null,
+    title: String(p.title ?? ''),
+    priority: Number(p.priority ?? 4),
+    sort_order: Number(p.sort_order ?? 0),
+    description: (p.description as string | null | undefined) ?? null,
+    created_at:
+      p.created_at instanceof Date
+        ? p.created_at
+        : new Date(String(p.created_at ?? Date.now())),
+    status: (p.status as BacklogPbi['status']) ?? 'ready',
+  }
+}
+
+function coerceStoryPayload(id: string, p: Record<string, unknown>): BacklogStory {
+  return {
+    id,
+    code: (p.code as string | null) ?? null,
+    title: String(p.title ?? ''),
+    description: (p.description as string | null | undefined) ?? null,
+    acceptance_criteria: (p.acceptance_criteria as string | null | undefined) ?? null,
+    priority: Number(p.priority ?? 4),
+    sort_order: Number(p.sort_order ?? 0),
+    status: String(p.status ?? 'open'),
+    pbi_id: String(p.pbi_id ?? ''),
+    sprint_id: (p.sprint_id as string | null | undefined) ?? null,
+    created_at:
+      p.created_at instanceof Date
+        ? p.created_at
+        : new Date(String(p.created_at ?? Date.now())),
+  }
+}
+
+function coerceTaskPayload(id: string, p: Record<string, unknown>): BacklogTask {
+  return {
+    id,
+    title: String(p.title ?? ''),
+    description: (p.description as string | null | undefined) ?? null,
+    priority: Number(p.priority ?? 4),
+    sort_order: Number(p.sort_order ?? 0),
+    status: String(p.status ?? 'todo'),
+    story_id: String(p.story_id ?? ''),
+    created_at:
+      p.created_at instanceof Date
+        ? p.created_at
+        : new Date(String(p.created_at ?? Date.now())),
+  }
+}

stores/product-workspace/types.ts

@@ -0,0 +1,140 @@
+import type { PbiStatusApi } from '@/lib/task-status'
+
+export interface BacklogPbi {
+  id: string
+  code: string | null
+  title: string
+  priority: number
+  sort_order: number
+  description?: string | null
+  created_at: Date
+  status: PbiStatusApi
+}
+
+export interface BacklogStory {
+  id: string
+  code: string | null
+  title: string
+  description: string | null
+  acceptance_criteria: string | null
+  priority: number
+  sort_order: number
+  status: string
+  pbi_id: string
+  sprint_id: string | null
+  created_at: Date
+}
+
+export interface BacklogTask {
+  id: string
+  title: string
+  description: string | null
+  priority: number
+  status: string
+  sort_order: number
+  story_id: string
+  created_at: Date
+}
+
+export interface TaskDetail extends BacklogTask {
+  _detail: true
+  implementation_plan?: string | null
+  acceptance_criteria?: string | null
+  requires_opus?: boolean
+  estimated_minutes?: number | null
+}
+
+export function isDetail(task: BacklogTask | TaskDetail): task is TaskDetail {
+  return (task as TaskDetail)._detail === true
+}
+
+export interface ActiveProduct {
+  id: string
+  name: string
+}
+
+export interface ProductBacklogSnapshot {
+  product?: ActiveProduct
+  pbis: BacklogPbi[]
+  storiesByPbi: Record<string, BacklogStory[]>
+  tasksByStory: Record<string, BacklogTask[]>
+}
+
+export type Op = 'I' | 'U' | 'D'
+
+export interface PbiRealtimeEvent {
+  entity: 'pbi'
+  op: Op
+  id: string
+  product_id: string
+  [key: string]: unknown
+}
+
+export interface StoryRealtimeEvent {
+  entity: 'story'
+  op: Op
+  id: string
+  product_id: string
+  pbi_id?: string
+  [key: string]: unknown
+}
+
+export interface TaskRealtimeEvent {
+  entity: 'task'
+  op: Op
+  id: string
+  product_id: string
+  story_id?: string
+  [key: string]: unknown
+}
+
+export type ProductRealtimeEvent =
+  | PbiRealtimeEvent
+  | StoryRealtimeEvent
+  | TaskRealtimeEvent
+
+export type ResyncReason =
+  | 'visible'
+  | 'reconnect'
+  | 'manual'
+  | 'unknown-event'
+  | 'stale-scope'
+  | 'mutation-settled'
+
+export type RealtimeStatus = 'connecting' | 'open' | 'disconnected'
+
+export interface OptimisticPbiOrderMutation {
+  kind: 'pbi-order'
+  prevPbiIds: string[]
+}
+
+export interface OptimisticStoryOrderMutation {
+  kind: 'story-order'
+  pbiId: string
+  prevStoryIds: string[]
+}
+
+export interface OptimisticTaskOrderMutation {
+  kind: 'task-order'
+  storyId: string
+  prevTaskIds: string[]
+}
+
+export interface OptimisticEntityPatchMutation {
+  kind: 'entity-patch'
+  entity: 'pbi' | 'story' | 'task'
+  id: string
+  prev: BacklogPbi | BacklogStory | BacklogTask | TaskDetail | undefined
+}
+
+export type OptimisticMutation =
+  | OptimisticPbiOrderMutation
+  | OptimisticStoryOrderMutation
+  | OptimisticTaskOrderMutation
+  | OptimisticEntityPatchMutation
+
+export interface PendingOptimisticMutation {
+  id: string
+  mutation: OptimisticMutation
+  createdAt: number
+}

stores/selection-store.ts

@@ -1,17 +0,0 @@
-import { create } from 'zustand'
-
-interface SelectionStore {
-  selectedPbiId: string | null
-  selectedStoryId: string | null
-  selectPbi: (id: string | null) => void
-  selectStory: (id: string | null) => void
-  clearSelection: () => void
-}
-
-export const useSelectionStore = create<SelectionStore>((set) => ({
-  selectedPbiId: null,
-  selectedStoryId: null,
-  selectPbi: (id) => set({ selectedPbiId: id, selectedStoryId: null }),
-  selectStory: (id) => set({ selectedStoryId: id }),
-  clearSelection: () => set({ selectedPbiId: null, selectedStoryId: null }),
-}))

tests/setup.ts

@@ -0,0 +1,84 @@
+import { beforeEach, vi } from 'vitest'
+
+// G6: vitest 4 + jsdom 29 mist localStorage/sessionStorage op globalThis.
+// MemoryStorage-binding zodat tests zonder echte browser draaien.
+class MemoryStorage implements Storage {
+  private store = new Map<string, string>()
+
+  get length(): number {
+    return this.store.size
+  }
+
+  clear(): void {
+    this.store.clear()
+  }
+
+  getItem(key: string): string | null {
+    return this.store.has(key) ? this.store.get(key)! : null
+  }
+
+  key(index: number): string | null {
+    return Array.from(this.store.keys())[index] ?? null
+  }
+
+  removeItem(key: string): void {
+    this.store.delete(key)
+  }
+
+  setItem(key: string, value: string): void {
+    this.store.set(key, String(value))
+  }
+}
+
+const localStorageMemory = new MemoryStorage()
+const sessionStorageMemory = new MemoryStorage()
+
+Object.defineProperty(globalThis, 'localStorage', {
+  value: localStorageMemory,
+  configurable: true,
+  writable: true,
+})
+Object.defineProperty(globalThis, 'sessionStorage', {
+  value: sessionStorageMemory,
+  configurable: true,
+  writable: true,
+})
+
+if (typeof window !== 'undefined') {
+  Object.defineProperty(window, 'localStorage', {
+    value: localStorageMemory,
+    configurable: true,
+    writable: true,
+  })
+  Object.defineProperty(window, 'sessionStorage', {
+    value: sessionStorageMemory,
+    configurable: true,
+    writable: true,
+  })
+}
+
+// G7: maak globalThis.fetch herconfigureerbaar zodat vi.spyOn / vi.fn-stubs
+// de eigenschap kunnen redefineren. Default Node 24 / jsdom 29 binding is
+// vaak non-configurable, wat vi.spyOn(globalThis, 'fetch') laat falen.
+const originalFetch = (globalThis as { fetch?: typeof fetch }).fetch
+Object.defineProperty(globalThis, 'fetch', {
+  value: originalFetch,
+  configurable: true,
+  writable: true,
+})
+
+beforeEach(() => {
+  localStorageMemory.clear()
+  sessionStorageMemory.clear()
+  vi.restoreAllMocks()
+  // Default fetch-stub voorkomt dat fire-and-forget ensure*Loaded calls
+  // (b.v. via setActivePbi) lekken naar het echte network. Tests die
+  // specifieke responses willen overrulen dit met vi.spyOn/vi.fn.
+  // G8: mockImplementation (niet mockResolvedValue) zodat elke call een
+  // verse Response krijgt — body wordt anders maar één keer leesbaar.
+  ;(globalThis as { fetch: typeof fetch }).fetch = vi
+    .fn()
+    .mockImplementation(() =>
+      Promise.resolve(new Response('null', { status: 200 })),
+    ) as unknown as typeof fetch
+})

tests/stubs/server-only.ts

@@ -0,0 +1 @@
+export {}

vitest.config.ts

@@ -3,12 +3,14 @@ import path from 'path'
 
 export default defineConfig({
   test: {
-    environment: 'node',
+    environment: 'jsdom',
     globals: true,
+    setupFiles: ['tests/setup.ts'],
   },
   resolve: {
     alias: {
       '@': path.resolve(__dirname, '.'),
+      'server-only': path.resolve(__dirname, 'tests/stubs/server-only.ts'),
     },
   },
 })