Adopt PosterChan's "encrypted events are the datastore" idea for two
per-browser bits of state, so they follow the user's npub across devices.
New shared engine (src/hooks/useSyncedAppData.ts):
- Stores one encrypted kind-30078 (NIP-78) event per d-tag, NIP-44
encrypt-to-self, modeled on the proven useStash pattern.
- Clobber-guard: re-fetch + re-decrypt the freshest remote copy and
MERGE the local patch in before publishing (never overwrites a field
another device just set).
- Debounced publisher (coalesces rapid writes, flushes on pagehide/
beforeunload) so frequent read-marker changes don't spam relays.
- No-op for anon / non-NIP-44 signers.
Read-state sync (src/hooks/useReadState.ts), d-tag skatespots:read-state:
- Unifies the four previously localStorage-only markers (notification
bell, DMs, crew chat, newsletter) into one synced blob.
- Merge = field-wise MAX (markers only move forward → commutative, safe).
- The four legacy hooks now re-export drop-in replacements with identical
signatures, so NO consumer component changed. localStorage stays as the
instant/offline/anon fast path; the relay copy hydrates and max-merges.
- Fixes the real bug where clearing a badge on one device left it lit on
another.
Preference sync (src/hooks/usePreferences.ts), d-tag skatespots:preferences:
- Mobile + desktop nav layouts now sync (language field wired for later).
- Merge = last-write-wins by updatedAt (a pref replaces, not accumulates).
- useNavPreferences / useDesktopNavPreferences adopt a synced layout when
present and mirror changes; public APIs unchanged, localStorage fallback
intact.
Docs: NIP.md gains a "Cross-device app data (kind 30078, encrypted)"
section documenting both d-tags, their content shapes, merge policies, and
the clobber-guard/debounce/anon safety notes.
Build + typecheck pass.
Co-authored-by: shakespeare.diy <assistant@shakespeare.diy>
