Web
The operational web application uses React and Next.js. It presents authorized domain projections and uses explicit API transports for commands and queries. This engineering site uses a different stack because its purpose is static explanation, not authenticated production work.
Native iOS
The iOS architecture is in an incremental SwiftUI/native migration. Native interfaces use shared identity, server contracts and permissions. Native interaction can take advantage of device capabilities without reproducing server authority in client-side rules.
Supported existing shell experiences can coexist during migration. A native implementation record or automated bridge test does not establish physical-device acceptance, App Store release or complete feature parity. Those claims need their own evidence.
Desktop
The Tauri macOS shell hosts the web application and adds selected local capabilities. It is not a separate copy of the application backend. A hosted page can change independently of native shell code, while native shell changes still have their own packaging and release lifecycle.
Offline behavior is bounded. The public model does not promise that all hosted screens work offline or that desktop runs a local Next.js runtime.
MCP
The stateless MCP service has an independent authentication boundary and accesses the public application API. It does not receive direct Firebase credentials merely because it is another client.
A tool-oriented interface has different interaction and admission concerns from a browser or a native screen. It can share domain contracts without sharing every UI or capability.
Shared contract, separate implementation
The design avoids two extremes: requiring identical interfaces on every platform, and giving each client a divergent model of canonical work. Shared server contracts preserve identity and ownership. Independent interfaces preserve useful platform behavior. Coverage remains incremental and should be stated per workflow rather than assumed from the presence of a client.
| Responsibility | Web | iOS | Desktop | MCP |
|---|---|---|---|---|
| UI | Web application | Native coverage varies | Hosted web shell | Tool interface |
| Authentication | Application identity | Shared server identity | Hosted application identity | Separate scoped boundary |
| Contracts | Server contracts | Server contracts | Hosted web contracts | Public API contracts |
| Offline capability | Not assessed | Not assessed | No parity claim | Stateless |
| Server API | Domain services | Domain services | Domain services | Scoped API |
| Local storage | Not assessed | Not assessed | Not assessed | No Firebase credentials |
| Release model | Application release | Incremental native migration | Desktop shell release | Integration release |