Five phases, each shippable on its own. AR and marketplace payments are sequenced early precisely because they carry the most technical risk — better to learn what's hard in month two than month eight.
0
Foundation
Weeks 1–4
Backend data model, City/Tour/Stop/Artist/Artwork schema live
Design system implemented natively (iOS + Android)
Admin console shell + auth + RBAC
1
Tours core
Weeks 5–9
Gallery + street art tour runtime: navigation, geofencing, audio
AR target photography and Stripe artist onboarding both depend on real artist relationships being in place — that outreach should start in Phase 0, in parallel with engineering, not wait for Phase 2/3 to begin.