ADR-004: Tauri v2 Migration (iced → Tauri v2 + WebView)

Date: 2026-03-04 Status: Accepted Deciders: Maekon maintainers

Background

The maekon-ui crate implemented a GUI based on iced 0.12. The following problems arose:

1. Rendering limitations — iced's immediate-mode renderer shows performance degradation with complex data visualizations (timelines, heatmaps).
2. Duplicate web dashboard — An equivalent web UI already existed via Axum + React. Maintaining two UIs increased cost.
3. Platform inconsistency — iced renderer behaviour differed across macOS, Windows, and Linux.

Decision

Remove iced and use Tauri v2 to wrap the existing React web dashboard in a native desktop shell.

Implementation

• src-tauri/ directory: Tauri main binary entry point.
• Embed the existing crates/maekon-web/ React app via Tauri WebView.
• IPC: tauri::command macro for Rust ↔ JavaScript communication.
• System tray: tauri::tray API.
• Auto-update: self_update (retained). The custom updater (src-tauri/src/updater/) provides SHA256 + Ed25519 verification, rollback, prerelease filtering, version floor enforcement, and a coordinator state machine — capabilities that tauri-plugin-updater does not cover. Migration was evaluated (2026-04-01) and rejected due to feature loss risk with no clear benefit.

Consequences

• ✅ Single UI codebase (React).
• ✅ Cross-platform consistency (WebKit/WebView2).
• ✅ Reduced dependencies by removing the maekon-ui crate.
• ⚠️ Tauri IPC learning curve.
• ⚠️ WebView memory overhead (~50 MB).

Alternatives Considered

Alternative	Reason Rejected
Keep iced	Complex UI limitations; dual UI maintenance cost
Egui	Same limitations as iced
Electron	Excessive memory and bundle size