ADR-0001: Flutter for the mobile app

Status:  Accepted
Date:    2026-05-02
Owner:   @satya

Context

Treeper ships on phones. We need iOS and Android from day one and we are a small / solo team. We do not (yet) need a web or desktop client.

Realistic options:

• React Native + Expo
• Flutter (managed Dart)
• Native iOS (Swift) + native Android (Kotlin), shared via KMP

Decision

Build the mobile app with Flutter, pinned per-project via fvm using the latest stable channel.

Alternatives considered

Option	Why not
React Native + Expo	Fine choice. Flutter wins for us on offline UI fidelity (custom maps, list re-orders) and on
	a single language for UI + business logic.
Native + KMP	Maximum quality, way too much code for a solo / small team to maintain twice.

Consequences

Positive

• One codebase for iOS and Android.
• Strong widget catalogue for the kinds of UIs Treeper needs (lists, drag, maps, image grids).
• Dart’s static typing keeps the codebase legible at scale.
• fvm ensures everyone runs the same SDK.

Negative / risks

• Flutter’s iOS share-extension story is rougher than RN; expect to drop to native code for the “forward-to-Treeper” extension when we ship F3.1.
• Dart talent pool is smaller than JS/TS — relevant if we hire later.

Follow-ups

• Add a .fvmrc at the repo root pinning the Flutter channel.
• Lint / format / test setup lives in apps/mobile.
• An ADR for state management (likely Riverpod) when we have evidence to decide.

References

• apps/mobile/README.md