Scrum4Me/docs/adr/0006-demo-user-three-layer-policy.md
Janpeter Visser 2b4b5bf719
feat(PBI-80): demo-user mag eigen UI-voorkeuren wijzigen (#194)
* feat(PBI-80): SprintSwitcher demo-fork (ST-1345)

Demo-sessies navigeren bij sprint-wissel direct via router.push, zonder
de geblokkeerde setActiveSprintAction aan te roepen. De server-action
behoudt zijn 403-guard als defense in depth.

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

* feat(PBI-80): NavBar demo-fork + URL-derived actief product (ST-1346)

Demo: product-switch in de NavBar navigeert direct via router.push zonder
setActiveProductAction. Voor de weergave (label + dropdown-highlight +
nav-links) leiden we voor demo de actieve product af uit pathname, zodat
de UI consistent is met de URL — de server-render houdt de seed-default
prop maar die wordt voor demo overschreven.

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

* docs(PBI-80): ADR-0006 addendum + demo-client-state patroon (ST-1347)

ADR-0006 krijgt een "Updated 2026-05-12"-sectie die de PBI-80-uitzondering
documenteert: client-side UI-prefs (filters, sort, layout, scope-keuze) zijn
voor demo toegestaan via in-memory store, terwijl alle data-mutaties three-layer
beschermd blijven. Patroon-doc beschrijft wanneer en hoe `isDemo` te gebruiken
in nieuwe componenten. CLAUDE.md quickref + docs/INDEX.md ge-update.

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

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-12 20:03:40 +02:00

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2.8 KiB
Markdown

# ADR-0006: Demo-user write protection enforced in three layers
## Status
accepted
## Context
Scrum4Me has a demo account that allows prospective users to explore the app without signing up. The demo user must never be able to create, update, or delete any data. A single guard at one layer is insufficient: a bug or a missing check in any one layer would expose a write path. See `docs/architecture/auth-and-sessions.md` and `docs/plans/ST-1110-demo-readonly.md` for implementation details.
## Decision
Write protection for the demo user is enforced at **three independent layers**:
1. **Network — `proxy.ts`:** The Next.js proxy middleware rejects all non-GET requests from demo sessions before they reach any route handler or server action.
2. **Server — every Server Action and Route Handler:** Each write endpoint checks `session.isDemo` and returns `403` immediately if true.
3. **UI — disabled buttons + `<DemoTooltip>`:** Write controls (create, edit, delete, reorder) are rendered as `disabled` with a tooltip explaining the demo restriction. No write request is ever sent.
## Consequences
### Positive
- Defense-in-depth: any single layer can fail independently without exposing a write path.
- Clear user feedback at the UI layer without relying on error responses.
- Straightforward to audit: search for `isDemo` to find all enforcement points.
### Negative
- Three enforcement sites for every new write operation — easy to miss one when adding a new feature.
- Mitigation: the `DemoTooltip` pattern is documented in `docs/patterns/` and enforced in code review.
## Updated 2026-05-12 — Exception for client-side UI preferences
PBI-80 relaxes the policy *for client-side UI preferences only*:
- **Allowed for demo:** product-switch and sprint-switch via URL navigation,
filters/sort, layout state (split-panes, collapsed PBIs, selections) —
routed through the in-memory `useUserSettingsStore`.
- **Why this is safe:** none of these touch the database. The demo user is a
single shared row, but each visitor's browser holds its own Zustand store
and URL state. A refresh resets to seed defaults; visitors never see each
other's choices.
- **Unchanged — three-layer enforcement still applies to:** all data mutations
(PBI/story/task/sprint create/update/delete/reorder), account fields
(username, password, email), role assignment, QR-pairing, web-push, and any
cron/webhook secrets.
- **Pattern for new demo-friendly features:** if it is UI state, route it
through `useUserSettingsStore.setPref` (which already has a demo-fork at
[stores/user-settings/store.ts:80](../../stores/user-settings/store.ts)) or
pure URL navigation via `router.push`. Never call a server action for demo.
See [docs/patterns/demo-client-state.md](../patterns/demo-client-state.md).