Borrow Dish base-class discipline for Android — ADR before Kotlin work starts

[stanvx]

Parent

Architecture review (2026-06-21). Slice 6 of 6 from the deepening series. Speculative — the Android Kotlin work has not yet started, so this is preventive architecture. Documented at android/rust/usbip-android/src/lib.rs:26.

What to build

Before any Kotlin UI/state code is written, copy the base-class discipline from Dish-Android wholesale:

• AbstractStateSource<S> — single owner of a StateFlow<S>, with val state: StateFlow<S> and an abstract protected fun compute(): S
• AbstractComposer<S, A> — translates a state into a Composable function; no business logic
• AbstractController<S, A> — accepts user actions, mutates the StateSource, never directly mutates state

Write an ADR (docs/adr/0007-android-base-classes.md) capturing the decision with a code skeleton inline. The base classes themselves live in android/core/src/main/java/com/anyplug/base/ and ship as a real, instantiable package even before the first concrete subclass lands.

This is cheap now (3 small files) and expensive to add later (every existing state-source would need to be retrofitted).

Acceptance criteria

• android/core/src/main/java/com/anyplug/base/AbstractStateSource.kt exists with KDoc explaining the discipline and a single abstract method
• android/core/src/main/java/com/anyplug/base/AbstractComposer.kt exists
• android/core/src/main/java/com/anyplug/base/AbstractController.kt exists
• ADR 0007 (docs/adr/0007-android-base-classes.md) explains the decision, references the Dish-Android original, and shows a code skeleton
• CONTEXT.md "module ownership" section has AndroidStateOwner, AndroidComposerOwner, AndroidControllerOwner entries pointing at these classes
• A unit test in android/core/src/test/java/com/anyplug/base/ proves the StateFlow round-trips a compute() result correctly
• No existing Kotlin file (MainActivity, ServerDiscovery, etc.) is refactored to use the new base classes — that's follow-up work, gated on this ADR

Blocked by

• Reconcile docs to code — name module ownership in CONTEXT.md, fix 12+ divergences #27 (Reconcile docs to code) — needs the Android ownership lines in CONTEXT.md before the ADR can land coherently