architecture

• One question per diagram: who uses it, how the app is built, the backend, what it relies on. The backend is Firebase only; there is no server of our own.
• How the app is built follows the data seam: screens read src/data/hooks.ts, writes land in the store first, and sync.ts carries them to Firestore.
• The diagrams are generated: edit the .json in architecture/, then run archify finalize architecture <name>.json <name>.html --quality showcase there. Never hand-edit the .html.
• Architecture is canon's, not the design set's: the designs are what Babul draws, and nothing else.
• Why each part of the stack was chosen is in the product's own CLAUDE.md.